Brain Bee Flashcards
1
Q
What are the brain’s three layers of protection?
A
Bones, meninges and ventricles
2
Q
What are the two bones that protect the CNS?
A
Cranium and vertebrae
3
Q
What is the durable outermost layer of the meninges?
A
The Dura Mater
4
Q
What is the thin, delicate, 2nd layer of the meninges?
A
The Arachnoid Mater
5
Q
What are the Pia Mater and Arachnoid Mater collectively known as?
A
The Leptomeninges
6
Q
What is the space between the Dura Mater and Arachnoid Mater known as?
A
The subdural space
7
Q
What is the thin, innermost layer of the meninges that adheres directly to the brain, going deep into its grooves?
A
The Pia Mater
8
Q
What is the important area between the arachnoid mater and pia mater that is filled with blood vessels and fine tissue projections known as?
A
subarachnoid space
9
Q
What are the fine tissue projections that connect the dura mater and arachnoid mater, and circulate CSF known as?
A
trabeculae
10
Q
What are neurons/nerve cells in charge of?
A
Transmitting and integrating information in the brain.
11
Q
What are dendrites?
A
Branched extensions of a nerve cell that receive inputs from other neurons
12
Q
What is the cell body/soma?
A
A part of a neuron that contains the nucleus and other organelles. It is where all the dendrites converge and their electrical inputs are combined.
13
Q
What are axons?
A
A single (often long) process which branches to form terminals that contact other neurons and/or cells.
14
Q
What are terminals?
A
The endings of the axon through which many neurons signal information to the next cell, generally using chemical neurotransmitters.
15
Q
What cells make up gray matter?
A
Neurons
16
Q
What cells make up white matter?
A
Glial cells
17
Q
What do glial cells do?
A
Maintain an optimal environment for neuronal function, by protecting neutrons, providing structural support,, scavenging debris, managing waste and supplying them with nutrients.
18
Q
What types of glia are found in the CNS?
A
Astrocytes, microglia, oligodendrocytes and ependymal cells
19
Q
What types of glia are found in the PNS?
A
Schwann cells and satellite cells
20
Q
What do astrocytes do?
A
Deliver nutrients from the blood to neurons and take waste products.
Control the chemical environment, like ions and transmitters, around neurons and other brain cells (the “extracellular environment” or “microenvironment”) to keep them healthy and regulate metabolism.
Responsible for controlling capillary blood flow, which in turn modulates the flow of chemicals between blood and neurons.
Astrocytes play an important role in repair and scarring of nerve cells in the CNS
Astrocytes provide a buffer reserve of “fuel” for cells as they contain glycogen (a large molecule made of glucose sub-unit molecules) which they can break down to release glucose during periods of high demand by neurons.
They also regulate excess K+ homeostasis.
21
Q
What do oligodendrocytes and Schwann cells do?
A
Provide a myelin sheath to insulate the axon of neurons, allowing faster connections. They also provide trophic support to neurons through secretion of neurotrophic factors.
Contribute towards maintaining an optimal extracellular environment
22
Q
What are microglia?
A
Specialized immune cells that make up the main active immune defense mechanism in the CNS.
A particluar type of macrophage (special white blood cells) only present in the CNS.
23
Q
What do microglia do?
A
They scavenge cell debris from dying neurons and other glial cells and are the “first responders” when there is damage to the CNS. The scavenging actions of microglia can prevents the build up of toxic waste substances but may also contribute to neurodegeneration.
They constantly and rapidly reorganize their shape by changing their processesdue signalling from K+ channel signals, this allows them to very efficiently scan the local environment to identify any insults to the CNS. their cell body doesn’t change shape, so that it doesn’t disturb local neuronal circuits.
Microglia play important roles in regulating the development of the brain after birth, and in brain plasticity in adulthood.
24
Q
What do ependymal cells do?
A
Line the brain’s fluid spaces (ventricles) to form a slight barrier between the fluid spaces and the cells, while producing CSF.
Ependymal cells have cilia, little hair-like organelles that face the cavity of the ventricles. The cilia time their movement to direct CSF and are can influence the distribution of neurotransmitters to neurons.
Some ependymal cells can divide and form neurons through the life of a cell, allowing neuroregeneration to occur.
These support cells can provide an environment that protects axon stumps from degeneration after damage, allowing alternate neuronal connections to grow and restore function.
25
What do satellite cells do?
Found only in the ganglion of the PNS, they regulate the external microenvironment and respond to neuronal injuries.
26
What do trophic molecules do?
Aid in the growth and development of other molecules.
27
What do tropic hormones do?
Stimulate glands to make other hormones.
28
How many axons can one neuron have?
1
29
What is the most diverse and common glial cells in the NS?
Astrocytes
30
Where are protoplasmic cells found?
In the gray matter
31
Where are fibrous cells found?
In the white matter
32
What is the Blood Brain Barrier made of?
A network of tightly packed endothelial cells
33
What do astrocytes do? (summary)
Neurogenesis (growth + development of nerve tissue
Synaptogenesis (formation of synapses between neurons
Immune Response
Glial Scars
Blood-Brain Barrier
Maintain Homeostasis
Vasomodulation (the neuronal regulation of blood flow)
34
What are the 2 division of the NS?
The Central Nervous Systema and Peripheral Nervous System
35
Where are nerves in the CNS located?
In the brain and spinal cord
36
Where are nerves in the PNS located?
Outside the brain and spinal cord
37
What are the 2 divisions of the PNS?
The autonomic NS
| The somatic NS
38
Where are neurons in the ANS located?
In deep internal structures (the gut, the heart, the lungs, the blood vessels...)
39
Where are neurons in the SNS located?
More superficially located structures (the skeletal muscles of the body, the eye, the ear...)
40
What are afferent neurons?
Neurons that run from the periphery (the body) to the CNS, carrying information to the CNS.
41
What are efferent neurons?
neurons running from the CNS to the periphery, carrying information to body parts (the periphery)
42
What groups are neurons in the CNS located in?
Structures called nuclei or fields
43
What groups are neurons in the PNS located in?
Structures called ganglia
44
What are bundles of nerve axons called?
Nerve Tracts (or fasciculus)
45
What makes white matter white?
The presence of a fatty substance called myelin
46
What do sequences of nucleus to tracts to nucleus to tracts... create?
Neuronal circuits
47
What do sequences of nucleus to tracts to nucleus to tracts... create?
Neuronal circuits
48
What does the SNS control?
Voluntary functions
49
What does the CNS control?
Involuntary functions
50
What does the Enteric NS control?
The gastrointestinal tract
51
what does the ANS control?
.Involuntary functions
52
What are motor efferent neurons?
Neurons that transmit information from the CNS to control muscles.
53
What are sensory afferent neurons?
Neurons that transmit information from sensory organs to the CNS.
54
What are the 2 types of interneurons?
Local Neurons
| Projection (tract) interneurons
55
What are the 2 types of interneurons?
Local Neurons
| Projection (tract) interneurons
56
Where are interneurons located?
Only in the CNS
57
What do interneurons do?
Transmit information from one neuron to the next neuron.
58
What do interneurons do?
Transmit information from one neuron to the next neuron.
59
What distance do local neurons transmit over?
Short distances between neurons within the one nucleus)
60
What distance do local neurons transmit over?
Short distances between neurons within the one nucleus)
61
What distance do projection neurons transmit over?
Long distances (between neurons located in two different nuclei)
62
What do neuroendocrine cells do?
Receive neural input and release hormones into the blood supply to influence distant target organs.
63
What do unipolar neurons have?
A single process and no dendrites
64
What is the principal type of sensory neuron in the NS?
Pseudo-unipolar cells
65
What do the soma of pseudo-unipolar neurons make up?
Sensory ganglia in the PNS
66
What are bipolar neurons?
Neurons with two extensions: one axon, and one dendrite, that are mostly sensory neurons
67
What are multipolar neurons:
Neurons with one axon and numerous dendrites
68
What does an axon extend from?
The soma
69
What region of neurons is the axon
The conducting region
70
What insulates myelinated axons
A myelin sheath
71
What is region is the axon hillock/initial segment?
The integration region
72
What is region is the axon hillock/initial segment?
The integration region
73
What is region is the axon hillock/initial segment?
The integration region
74
What is region of neurons is the axon hillock/initial segment?
The integration region
75
What does the integration region do?
It collects all the information that a neuron receives before determining if there is sufficient excitation to relay that excitatory information along the conducting region.
76
What does a cells cytoskeleton consist of?
Micro-filaments and neuro-filaments for rigidity, and microtubules for transport
77
Where are axon terminals located on a neuron?
Specialized regions called synapses
78
What region of neurons are synapses
The output region
79
What region of neurons are synapses
The output region
80
What region of neurons are synapses
The output region
81
What do dendrites receive?
Synapses/inputs
82
What are the small protrusions on dendrites called?
Dendritic spines
83
What occurs at dendritic spines?
Excitatory inputs are provided by other neurons, they are the region through which chemicals flow into the cell when it is activated.
84
What protein allows dendrites to change shape (elongate and contract)?
Actin
85
What are the 3 classification of dendritic spines?
Thin
Mushroom
Stubby
86
What are thin dendritic spines known as?
Learning spines: they have been shown to grow when a new task is being learned.
87
What are mushroom dendritic spines known as?
Memory spines they are formed from the thin spines when learned tasks are remembered.
88
At different stages of life, as well as in different disease states, different proportions and density of ___ are observed?
Dendritic spines
89
Alcoholism is associated with a ____ in dendritic spine density.
decrease
90
With learning, dendritic spine density ___
increases
91
What are microtubules used for in neurons?
Transport of nutrients and waste products and the chemical neurotransmitters used to transmit information from the neuron’s terminals to the next cell/s in the chain. (Packages of nutrients or wastes are carried like along a conveyor belt along the outside of the microtubule.)
92
The accumulation of organelles and particles in one area of a neuron results in ___
swelling of the axon and eventually in disconnection and lesioning of the axon (axotomy) - leading to neuronal death.
93
What are the myelin sheaths of axons formed by (myelinated fibres)?
Schwann cells (in PNS) or oligodendrocytes (in CNS).
94
In myelinated axons, the glial cell wraps itself around a part of the axon and winds itself tighter and tighter by ___
squeezing all its own content out to the outermost winding, so that all the inner windings of the sheath consist only of the cell membrane of the glial cell.
95
What insulates some axons?
Myelin sheath
96
What do myelin sheathes prevent that results in a speeding up of flow of information?
Leakage of current
97
What do neurons do at their synapses?
contacts other cells to relay information or commands. (It is the function output region of a neuron)
98
What is the gap that separates cells called?
A synaptic cleft
99
How wide is a synaptic cleft?
approx. 20nm (nanometers)
100
What do neurons use to carry information across the synaptic cleft?
chemical neurotransmitters
101
What is the presynaptic neuron?
The signalling neuron
102
What is the postsynaptic neuron?
The target cell
103
When information is being sent from neuron to cell, what regions are sending and receiving the information?
The pre-synaptic neurons terminals to the post-synaptic neurons receptors
104
What do micro- and neuro- filaments provide?
A framework for structural rigidity.
105
What does the input region include
The soma and dendrites
106
What are the CNS and PNS connected to each other by?
Afferent and efferent neurons
107
What is the CNS?
The control center that processes all the information it receives from sensory neurons about the environment, and decides whether it should make a response or do nothing.
108
What are the planes of section?
The horizontal plane
The coronal plane
The sagittal plane
109
In the brain, what is the center referred to as?
The midline
110
What are structures close to the brain's midline called?
Medial
111
What are structures far from the brain's midline called?
Lateral
112
What are structures on both sides of the brain's midline called?
Bilateral
113
What axis describes how close something is to the spinal cord/brain
The proximal-distal axis
114
In the proximal-distal axis, what are hands and feet considered?
Distal
115
In the proximal-distal axis, what is the trunk considered?
Proximal
116
What is the axis that describes whether something is to the front or back of the body?
The anterior-posterior axis
117
What axis describes whether something is to the top to the bottom?
The superior-inferior axis
118
What axis describes whether something is towards the belly or back?
The ventral-dorsal axis
119
What axis describes whether something is towards the head or tail?
The rostral-caudal axis
120
What is the spinal cord?
A long tubelike structure found inside the vertebrae, that is connected to the end of the brain stem.
121
What is the main function of the spinal cord?
To connect the brain to the nerves of the PNS; it is the main pathway for the brain to send information to the periphery
122
What are the 5 regions of the spinal cord?
```
The cervical region
The thoracic region
The lumbar region
The sacral region
The coccyggal nerve
```
123
How many pairs of spinal nerves are there?
31
124
What is the hole in the center of the spinal cord?
The central canal
125
What is the central canal filled with
CSF (which helps in nourishing the nerves tissue and acts as a shock absorber)
126
What is in a spinal nerve?
Nerve tracts (fascicles) and blood vessels
127
What is the membrane surrounding the spinal nerve called?
The epineurium
128
What is the membrane surrounding a nerve tract/fascicle called?
The perineurium
129
What do fascicles/nerve tracts cotain?
Many neurons
130
What is the membrane surrounding a neuron in the spinal nerve called?
The endoneurium
131
What is the dorsal root of a spinal nerve for?
Sensory afferent neurons
132
What is the ventral root of the spinal cord for?
Motor efferent neurons
133
What are the 3 main regions of the brain?
The brainstem
The cerebellum
The cerebrum
134
How many pairs of cranial nerves are there?
12
135
What arteries supply the brain with blood?
The internal carotid artery
| The vertebral artery
136
What do the two vertebral arteries join to form?
A single basilar artery
137
Where do the two vertebral arteries join?
on the ventral surface of the hindbrain.
138
What does the basilar artery divide to form?
The two posterior cerebral arteries
139
Where does the basilar artery divide?
Near the front end of the pons
140
What does the internal carotid artery form?
the anterior and middle cerebral arteries.
141
What is the oldest part of the brain?
The brainstem
142
What is the brainstem involved in?
Involuntary body functions (functions that you do not control through conscious thinking.)
143
What does the brainstem continue from?
The spinal cord
144
Where does the brain stem join the forebrain?
At the top end (rostral end)
145
What are the 2 main parts of the brainstem?
The hindbrain and midbrain
146
What is the rostral part of the hindbrain?
The pons
147
What is the caudal part of the hindbrain?
The medulla oblongata
148
How many neuromeres/segments is the midbrain made of?
2
149
How many neuromeres/segments is the hindbrain made of?
12
150
What is the hindbrain segment closest to the midbrain called?
the isthmus
151
What are the neuromeres of the hindbrain called
the isthmus
| rhombomeres (r1 to r11).
152
What is the cerebellum involved in?
control of fine-movements
153
What does the cerebellum grow out of?
The rostral hindbrain
154
What part of the brain is above the pons?
The midbrain
155
Where are axons from the midbrain sent to?
The cerebellum, to modulate the activity of neurons in higher centers of the brain in the context of functions like sleep, attention or reward.
156
What are the two small "hillocks" of neurons in the Midbrain?
The colliculi
157
What are colliculi involved in?
Relaying auditory information or in automatic reflex responses where we move our heads and/or eyes to a sudden unexpected sound or object or touch.
158
What are the brainstem contains centers (collections of nuclei) that send pathways to keep the forebrain awake and alert called?
The Ascending Arousal System (AAS)
159
What is a corridor through which pathways (tracts) travel from forebrain to cerebellum and spinal cord, and from spinal cord to forebrain.
The brainstem
160
The brain stem is connected to motor neurons and sensory receptors by what?
ten pairs of cranial nerves: Cranial Nerves III - XI
161
Where does the oculomotor (III) cranial nerve arise from?
The midbrain
162
Where do cranial nerves IV-XI arise from (there is 9 of them)?
the hindbrain
163
What do the large myelinated tracts in the brain stem include?
descending tracts from the cerebral hemisphere, ascending tracts carrying sensory information to the thalamus, and the cerebellar input and output systems
164
How much of the brain's volume does the cerebellum take up?
10%
165
How much of the brains neurons are in the cerebellum
Over half
166
What skills does the cerebellum control?
Coordination, balance, posture, and movement.
167
How much of the brain's volume does the cerebrum take up?
83%
168
Just above the midbrain and between it and the cerebrum lies what part of the brain?
The Diencephalon
169
The Diencephalon consists of structures lying on either side of what?
the fluid-filled third ventricle.
170
What are the ventricles?
a set of four interconnected fluid-filled cavities in the brain, part of the protective elements of the CNS.
171
What are the names of the 4 ventricles?
right and left lateral ventricles (the first and second ventricles)
third ventricle
fourth ventricle
172
Which ventricle is continuous with the central canal of the spinal cord.
The 4th ventricle
173
What do the ventricles produce and contain?
CSF: which bathes and cushions the brain and spinal cord.
174
What are the collection of nuclei in the diencephalon called?
The thalamus
The hypothalamus
(it also contains the epithalamus and the sub-thalamus.)
175
Where must information be sent before it arrives at the cortex in the cerebrum
The thalamus
176
What separates the different thalamic subparts?
A system of myelinated fibres
177
Where is the thalamus in the brain?
It is a midline symmetrical structure within the brain situated between the cerebral cortex and midbrain.
178
The thalamus relays sensory and motor signals to where?
The cerebral cortex
179
Thalamic nuclei have strong reciprocal connections (to-and-fro connections) with the cerebral cortex that are believed to be involved with what?
consciousness.
180
What does the thalamus play a major role in?
regulating arousal, awareness level, and activity.
181
Where is the hypothalamus?
An almond-sized structure just below the thalamus, is a mass of nuclei in such close proximity to each other, they look like a single structure anatomically
182
What does the hypothalamus perform?
Vital functions (e.g., regulation of certain metabolic processes), most of which relate directly or indirectly to the regulation of activities involving internal organs.
183
What does the hypothalamus perform must of its functions via?
hormones that it releases or whose release from the pituitary gland it controls, and
nerve connections to other brain regions to control the ANS that controls internal body activities
184
what are the prominent nuclei within the hypothalamus?
the suprachiasmatic, paraventricular, ventromedial, and mammillary nuclei.
185
hypothalamic outputs can be divided into what?
neural projections and endocrine hormones.
186
What body functions do the hypothalamus control?
Body temperature, hunger, thirst, fatigue, sleep, complex homeostatic functions and circadian cycles.
187
The hypothalamus produces and secretes a wide variety of neurohormones that lead to what?
the release or inhibition of hormones from the pituitary gland below the hypothalamus.
188
The hypothalamus produces and secretes a wide variety of neurohormones that lead to what?
the release or inhibition of hormones from the pituitary gland below the hypothalamus.
189
What does the pituitary stalk connect the hypothalamus to?
the pituitary gland
190
What are the 2 parts of the pituitary gland?
the anterior and posterior pituitary.
191
Through what does the hypothalamus pass signals back and forth between the anterior and posterior pituitary?
the neurohypophysis and median eminence.
192
What is the posterior pituitary is made up of?
tissue derived from the hypothalamus
193
what is the anterior pituitary is derived from?
epithelial tissue.
194
What are hormones produced in the hypothalamus secreted by?
The pituitary gland
195
the anterior pituitary produces its own hormones under the control of what?
releasing factors (hormones) produced in the hypothalamus
196
The hypothalamic endocrine control is located where?
in the paraventricular nucleus which secretes the releasing hormones.
197
What does the SCN sits on top of?
the optic chiasm at the base of the brain
198
What does the SCN also receives direct input from to synchronize the clock with day and night.
the retina
199
What does the subthalamus connect to?
the globus pallidus
200
what is the globus pallidus?
a basal nucleus of the telencephalon.
201
Where does the subthalamus receive afferent connections from?
the substantia nigra and striatum
202
What does the subthalamus regulate?
skeletal muscle movement
203
The epithalamus functions as a connection between what?
the limbic system and other parts of the brain.
204
Some functions of the epithalamus include:
the secretion of melatonin by the pineal gland (involved in circadian rhythms) and regulation of motor pathways and emotions.
205
Where is the epithalamus located?
it is a dorsal posterior segment of the diencephalon, that is also connected to the limbic system and basal ganglia.
206
Where is the pineal gland located?
In the epithalamus
207
What is the main function of the epithalamus
Secretion of melatonin by the pineal gland
208
What is another name for the cerebrum of the brain?
The telencephalon
209
What can the cerebrum be divided into
A left and right hemisphere
210
What is the left hemisphere more involved in?
logical thinking
211
What is the right hemisphere more involved in?
creative activities
212
What are the two hemispheres of the cerebrum connected by?
3 nerve tracts
213
What is the most prominent nerve tract connecting the hemispheres of the cerebrum called?
The corpus callosum
214
What is the outer covering of gray-mater in the cerebrum called?
the cortex
215
What structures does the cerebrum contain?
the hippocampus, amygdala, olfactory bulb, and basal ganglia.
216
what is the innermost layer of the cerebrum?
the basal ganglia
217
what are the basal ganglia?
collections of subcortical nuclei in each hemisphere that help regulate voluntary movements
218
What activities does the cortex play a role in?
Consciousness, thinking, personality, memory, learning, attention, language, perception and movement.
219
What activities does the cortex play a role in?
Consciousness, thinking, personality, memory, learning, attention, language, perception and movement.
220
What activities does the cortex play a role in?
Consciousness, thinking, personality, memory, learning, attention, language, perception and movement.
221
What is the back block of the cerebrum?
The sensory block: it processes sensory information leading to a conscious awareness of the world around us.
222
How much of the cerebrum does the sensory block take up?
60%
223
What is the middle block of the cerebrum?
The motor block: it controls directed and planned movements, including overcoming obstacles in the way.
224
How much of the cerebrum does the motor block take up?
20%
225
What is the front block of the cerebrum?
The executive block: controls our executive functions, which determine our personality, consciousness and thinking.
226
How much of the cerebrum does the executive block take up?
20%
227
What are the ridges of the cortex called?
Gyri
228
What are the shallow grooves of the cortex called?
Sulci
229
What are the deep grooves of the cortex called?
fissures
230
what separates the cortex into the two hemispheres?
longitudinal fissure
231
what divides each hemisphere into lobes?
Deep sulci
232
What are the lobes of the brain?
the frontal lobe
the parietal lobe
the temporal lobe
the occipital lobe
233
How many cortical layers are there?
6
234
What happens in the upper layers of the cortex?
information is integrated, and where different forms of learning occur.
235
What happens in the middle layers of the cortex?
these are the input layers, receiving information from the lower regions of the brain.
236
What happens in the inner layers of the cortex?
Axons are sent to other brain regions.
237
What are the sub-cortical structures of the cerebrum?
the hippocampus, amygdala, olfactory bulb, and basal ganglia.
238
Where is the amygdala located?
In the temporal lobe rostral to the hippocampus, with one amygdala in each half of the brain in the left and right temporal lobes.
239
What is the amygdala involved in?
Complex behavioural and emotional responses - related to fear, to social organisation, in evaluating the emotionality of situations, and for learning based on reward or punishment.
It helps us recognise potential threats and then works through the ANS to help prepare us for fight-or-flight reactions, it causes an increase in heart and breathing rate.
240
What is the limbic system?
A connected set of structures that includes parts of the thalamus, hypothalamus, hippocampus, the amygdala and olfactory bulb.
241
What is the amygdala part of?
The limbic system
242
What does the limbic system (including the amygdala) regulate?
Emotions and behaviours related to fear and motivation.
Memory formation and consolidation, especially emotionally important memories. This is done together with the hippocampus, which is adjacent to the amygdala.
243
What are the major basal ganglia nuclei that control movement?
the striatum and the globus pallidus, both located deep in the cerebrum.
244
What are the main parts of the striatium?
The caudate and putamen
245
The basal ganglia works with a structure called the ___, in the midbrain, to coordinate and make smooth a sequence of behaviours to achieve a target desired outcome movement
substantia nigra
246
The globus pallidus is a layered nucleus that lies where?
just medial to the putamen
247
The hippocampus is found where?
Under the cerebral cortex, in the medial temporal lobe
248
What is the hippocampus involved in?
How information is moved from short-term memory to long-term memory and consolidated there,
and in spatial memory that enables navigation
Has a role in the formation of new memories about experienced events (episodic or autobiographical memory The proximity of the hippocampus to the amygdala, which is involved in emotions, allows for easy interactions between them and may explain the way that emotion is often tied up to memories of specific episodes.
249
The hippocampus, including the dentate gyrus has what shape?
A curved tube
250
The hippocampus is a well-established area for the study of what?
the phenomena of long-term potentiation (LTP) and long-term depression (LTD) in the transfer of information between neurons, phenomena that are believed to play a role as the neural substrate of memory.
251
Why is it difficult to find and treat neurodegenerative diseases?
Because brain functions involve widely-distributed areas that are all interconnected, it is difficult to uniquely pinpoint a specific brain region as being responsible for a particular functional problem.
It also makes it difficult to treat disorders - when we target an area to treat a disease or disorder, we don’t know what the upstream (higher-up) or downstream (lower-down) effects might be.
252
What are the 3 main factors that contribute to the aging of the brain?
Oxidative stress
Immune Dysfunction
Impaired protein recycling
253
What is the main region of the brain affected by neurodegenerative diseases?
The cortex
254
What is neural signaling?
When neurons receive input or commands, and then transmit this information along their length, relay the information or command to the next neuron in the series.
255
What are the two ways for neurons to do neural signaling
Through the flow of current (electrical signalling)
| Through the flow of chemicals (chemical signalling)
256
What is a cell that is being relayed information by a neuron called?
A target cell
257
What do neutrons have a different of across the cell membrane?
electrical charge
258
Is the inside or outside of a neuron more negative?
The inside
259
Is the difference of electrical charge of a neuron across the membrane or on either side of the cell membrane alone?
Across the cell membrane
260
What is the difference in charge across the cell membrane?
-70mV
261
Why is a neurons membrane polarized?
Because across the cell membrane there is a difference in electrical charge
262
What is the difference in electrical potential known as?
The Resting Membrane Potential (EM or RMP)
263
What is it called when the RMP becomes less negative than the resting value?
de-polarized
264
What is it called when the RMP becomes more negative than the resting value?
hyper-polarized
265
Where are separations in charge across the membrane found?
many cells, as well as intra-cellular membrane-bounded organelles such as mitochondria, peroxisomes, and lysosomes.
266
In mitochondria, the importance of the loss of the separation in charge across its membrane results in what?
the failure of the chain of molecules used to produce the energy molecule, ATP. Ending the useful life of that mitochondrion.
267
What do neurons use when they carry information along their length?
current flow (electrical signaling)
268
What do neurons use to relay information to the next neuron in a series?
chemical flow (chemical signaling)
269
In biological systems, what is charge carried by?
Ions
270
The difference in charge across the cell membrane must be due to differences in the movement of ___ across the membrane.
ions
271
In neurons, the RMP is due to that, at rest, the nerve allows ___ to move across the cell membrane more easily than they allow ___ to move across.
1. potassium (K+) ions
| 2. sodium (Na+) ions
272
what do neurons use to maintain the movement of ions across the two sides of the cell membrane (to maintain a constant RMP)
An 'active pump'
273
What does 'active' mean in a biological system?
That it requires energy to conduct activity
274
If the function of this pump were inhibited, what would occur?
the balance of ions would not be maintained and then the RMP would be lost
275
In neurons, what will failure to maintain the RMP result in?
failure of the neuron to signal information, possibly resulting in harm or death to person.
276
In neurons, what will failure to maintain the RMP result in?
failure of the neuron to signal information, possibly resulting in harm or death to person.
277
If a neuron wants to signal that it has received an input, what must it do?
change the RMP, by changing the flow of ions, resulting in a current flow across the neutrons length
278
What are ions?
Charged particles, with an excess or deficit of electrons relative to protons
279
As the current flows along a neutron, it leaks out and so has to be recharged, how is this done?
By producing an action potential
280
What is an action potential
a large change in the membrane potential; a change that is so large that it provides a reservoir of "new energy" to power the information further along the neuron.
281
What is an action potential
a large change in the membrane potential; a change that is so large that it provides a reservoir of "new energy" to power the information further along the neuron.
It is a series of changes that occur in the RMP when the neuron receives an input
282
In the Action Potential, the resting membrane potential
goes from a rest value of -70mV all the way to +30/+40mV, then back down to -90mV, then back to rest (-70mV)
283
How long does an AP go for?
Very brief- 2 milliseconds long
284
What is the rapid series of changes in the resting membrane potential called?
the Action Potential (AP; or nerve impulse or nerve spike).
285
This change occurs at a very localized point along the neuron and as it occurs, the current is already flowing to where?
adjacent parts of the neuron; to produce an AP at those points.
286
What happens when the current is flowing to adjacent parts of the neuron; to produce an AP at those points?
Information is spread away from the site which first triggered the AP
287
What is current?
The movement or flow of an electrical charge
288
Why is the flow of information across a neuron quite a slow process?
Because an AP is generated at every adjacent point along the neuron
289
What are the two ways that the flow of information can be sped up?
Increasing the diameter of the neuron
Insulating the neuron with a myelin sheath
These both reduce the number of AP points, speeding up the flow of information
290
What is the gap between neurons sometimes bridged by so neurons only have to use electrical signaling?
special channels
291
Why can't electrical signaling be used to transfer information across the gaps between the neurons?
Because the current/ions would be washed away in the fluid found between cells
292
Why is there an unbridged gap between neurons that requires chemical signaling?
Because usually, you don’t want commands from one cell to instantaneously produce a response in the target cell. You want the target cell to get a number of different commands or inputs which it can then balance off, to “decide” whether to respond.
293
What are the 2 general types of chemical signaling?
synaptic signaling
| non-synaptic signaling
294
what is the synaptic cleft?
A gap across which a neuron contacts a target cell
295
What is synaptic signaling used by?
only by neurons
296
What is non-synaptic signaling used by?
neurons and non-neuronal cells
297
In synaptic signaling what chemical agents are used?
neurotransmitters
298
What distance is involved in synaptic signaling?
short distances
299
What chemical agents are used in non-synaptic signaling?
Hormonal and local chemical mediators
300
What local chemical mediators are used in synaptic signaling?
Paracrine and autocrine
301
What distance is non-synaptic signaling using hormonal chemical chemical agents involved in?
long and very long distances
302
What distance is is non-synaptic signaling using paracrine local chemical mediators involved in?
short (adjacent cells)
303
What distance is is non-synaptic signaling using autocrine local chemical mediators involved in?
very short (on to self)
304
The use of chemicals is a ___ for signaling information in the body.
ubiquitous (found everywhere) mechanism
305
What does chemical signaling require?
Chemical signals released by a cell.
| A cell with specialized structures called receptors, to bind the chemicals and produce a response.
306
What chemicals are generally used to transmit information for short periods of time, with (generally, but not always) short-lasting effects.
Water-soluble chemicals
307
What chemicals tend to be hormones with long-lasting effects, e.g., in growth and development, in hormonal cycles like the menstrual cycle etc.
Lipid-soluble chemicals
308
What types of chemical signaling are water-soluble chemicals found in?
Synaptic and non-synaptic signaling (both neurons and non-neuronal cells)
309
What types of chemical signaling are lipid-soluble chemicals found in?
Non-synaptic signaling (non-neuronal cells only)
310
what are the specialized structures on target cells for chemicals to bind to on the target cell called?
receptors
311
what are the specialized structures on target cells for chemicals to bind to on the target cell called?
receptors
312
What is the location of a receptor related to?
the type of chemical they bind
313
what chemicals cannot penetrate the cell membrane of the target cell.
Water-soluble chemicals
314
where are receptors for Water-soluble chemicals located?
in the membrane of the target cell and facing the world outside the cell.
315
What chemicals are membrane-bound
water soluble chemicals
316
what type of chemicals can penetrate the cell membrane?
Lipid-soluble chemicals
317
Where are receptors for Lipid-soluble chemicals located?
inside the cell, or on the cell surface
318
What type of chemicals are intracellular
Lipid-soluble chemicals
319
What are the types of receptors for water soluble chemicals?
receptors that form ion channels
receptors linked to G-proteins
receptors linked to tyrosine kinase
320
What are receptors?
specialized structures on cells that chemicals bind to in order to elicit an effect.
321
All receptors have a particular structural region that can bind chemical signals, what is it called?
the binding site
322
What is the normal chemical that binds to a binding site called?
A ligand or agonist
323
Only a part of the ligand – not the whole ligand - binds to the binding site. So two chemicals with ___ can fit into the binding site and bind to the receptor
similar structures
324
Why can drugs and medications bind to a binding site?
they have a similar structure to the ligand
325
When drugs and medications bind to binding site they either:
elicit similar response to the agonist (acts as the agonist)
or
blocks the binding site without eliciting a response itself but preventing the natural ligand from eliciting a response (act as an antagonist).
326
The effects of the ligand are to bind to the appropriate receptor(s) and cause a ___ in the receptor.
shape change
327
when a ligand binds to a binding site, what leads to the cellular response in the target cell?
the shape change in the receptor
328
what are the two types of receptors?
Membrane-bound receptors
| Intra-cellular receptors
329
In some receptors the binding of the ligand to the binding site doesn’t itself affect the movement of ions across the membrane instead:
the binding of the ligand changes the shape of the receptor on the inside of the target cell.
The change allows a molecule found in the cell to bind to the receptor, resulting in responses in the target cell.
330
Usually ___ are used to produce slower, but long-lasting, changes in the target cell because the ___ leads to actions on the cell’s DNA.
Since DNA is the genetic material of the cell, affecting the DNA will alter the way proteins and other molecules are produced, leading to long-term changes.
1. intracellular receptors
| 2. receptor-ligand interaction
331
What is the affect of membrane-bound receptors that form ion channels?
The voltage changes directly
332
What is the affect of membrane-bound receptors linked to G-proteins?
. The voltage changes indirectly through the G-proteins or 2nd messengers
. Cellular changes indirectly through 2nd messenger which act on biochemical and genetic (DNA) processes.
333
What is the affect of membrane-bound receptors linked to Tyrosine kinase?
Alters biochemical function to affect cell function
334
What is the affect of intracellular receptors that bind to DNA?
Alters biochemical function to affect cell function
335
Extracellular signal causes ___ which causes conformational change which causes ___
1. Binding to receptors
| 2. Cellular response
336
In membrane bound receptors, binding of the ligand to the receptor site will change what?
the movement of ions across the membrane
337
Different regulatory sites can change what?
how ligands elicit responses
338
What is the binding site for in a NDMA type glutamate receptor?
glutamate
339
What is the binding site for in a NDMA type glutamate receptor?
glutamate
340
What are the regulatory sites for in a NDMA type glutamate receptor?
Glycine, zinc, PCP, and Mg2+
341
What is the regulatory site for a Kainate type glutamate receptor
zinc
342
What is the NDMA type glutamate receptor critically involved in?
learning and memory
343
What is the Kainate type glutamate receptor critically involved in?
Everyday transmission of information between neurons
344
What is the Kainate type glutamate receptor critically involved in?
Everyday transmission of information between neurons
345
What is the chemical GABA (Gamma-amino-butyric acid)
An inhibitory transmitter
346
What is an inhibitory transmitter?
A receptor hat it reduces the likelihood of the target cell responding. It is a major way the brain can prevent a cell from responding when not needed.
347
What two regulatory agents enhance the inhibitory affect of GABA?
benzodiazepines (BZDs) and barbiturates
348
Agents that bind to regulatory sites on GABA receptors on their own will ___ GABA receptors, but binding all together at the same time will cause the channel pore to open even wider and cause ___ of the cell
1. Bind and activate
| 2. Major suppression
349
Each sensory system has ___ to cope with a different type of ___
1. evolved
| 2. stimulus
350
all sensory systems have to:
convert the physical energy of some stimulus to which they are specialized into a biological response.
351
Action potentials occur in ___ that will therefore carry the information about the ___ to the brain for ___ , and many other things.
1. nerve fibres
2. stimulus
3. interpretation and learning
352
conversion of physical stimulus energy to biological energy, leads to:
the production of action potentials, or changes in the timing and number of action potentials.
353
Our senses are not just windows to the external world but also the drivers of much of our ___
internal world of thoughts, feelings, desires and memories.
354
The eye is specialized to tell us about:
the features of visual objects through detection of electromagnetic radiation emanating from them.
355
The ear is specialized to detect:
the pressure waves that make up sound.
356
Our tongues and our noses are specialized to detect:
the food-borne or air-borne chemicals in what we taste or smell.
357
what two steps do all sensory systems do?
Convert the physical energy of an appropriate stimulus into a biologically meaningful form.
Encode that information in the form of APs in nerve cells that carry that information to the brain as a train of APs.
358
In the brain there are great similarities between the way in which the ___ for each sense ___ the information they receive from their specific ___.
1. specialized brain areas
2. process
3. sensory peripheral elements
359
Our senses detect only a ___ of the ___ in a ___.
1. small amount
2. energy
3. stimulus domain
360
In every species, each ___ responds only to a ___ in that domain of stimuli
1. sensory modality
| 2. specific range of stimuli
361
The range of a stimulus energy possessed by an animal is related to what?
the evolutionary niche occupied by the animal.
362
what is Johannes Muller’s Law of specific nerve energies?
the nature of perception is defined by the pathway over which the sensory information is carried.
363
In every sensory system we will find specialized cells, ___, that contain mechanisms and processes that allow them to ___ to only ___ type of ___.
1. receptors
2. respond
3. one
4. physical stimulus
364
What do systems detecting the state of things in external undertake? and what are their receptors called?
Exteroception
| Exteroceptors/Extero-receptors
365
What are systems detecting the relationship of our body to the world (position and movement of limbs & body in space) called? and what are their receptors called?
Proprioception
| Proprio-receptors / Proprioceptors
366
What are systems that detect the state of things within the body are undertaking? What are their receptors called?
Interoception
| Intero-receptors/Interoceptors
367
What are sensory systems that respond to stretch or deformation are undertaking? What are their receptors? Examples: Hearing, Balance, Blood pressure, Muscle stretch, Gut filling, Proprioceptors.
Mechano-reception
| Mechano-receptors
368
What are sensory systems that respond to light are undertaking? what are their receptors? – Example: Vision.
Photoreception
| Photoreceptors
369
What are sensory systems that respond to chemicals are undertaking? What are their receptors? – Example: Taste, Smell, Blood gases, Osmoreceptors (that monitor fluid composition).
Chemo-reception
| Chemo-receptors
370
What are sensory systems that respond to changes in temperature are undertaking? What are their receptors? Example: Somatosensation (sensations from our body, both outside and inside).
Thermo-reception
| Thermo-receptors
371
What are sensory systems that respond to painful / damaging stimuli are undertaking? and what are their receptors? Example: Somatosensation (sensations from our body, both outside and inside).
Noci-reception/Nociception
| Noci-receptors/Nociceptors
372
Where do APs occur?
Nerve fibres
373
What are examples of peripheral components?
The eye, the ear, the skin
374
What are examples of central components?
The brain, the spinal cord
375
What do peripheral components do?
convert the physical energy of a stimulus into a biological form for transmission to the spinal cord and brain (central components).
376
The brain interprets sensory inputs to give us:
a sense of the world, influencing learning and cognition and for evoking and linking to memories.
377
All sensory systems have to get ___ efficiently to the region where they can be ___ into a biological response.
1. stimulus energy
| 2. decoded
378
All sensory systems have to have ___ that convert the stimulus energy to a ___. All sensory systems have to have structures to convey the information from the biological response to the ___ where it can be interpreted or new things learnt, or memories formed.
1. specialized structures
2. biological response
3. brain
379
What are the 3 parts of the Peripheral Sensory System?
```
Accessory structures
Receptor Cells
Output Neurons (afferent nerve fibres)
```
380
What do accessory structures do?
Detect stimulus energy, translate stimulus to receptor cells (translation)
381
What do receptor cells do?
Perform the receptor/generator potential- transduce stimulus to a biological response (transduction)
382
What do output neurons do?
Convert receptor potential to APs- transmit information to the CNS (transmission)
383
What are the 3 stages of the Peripheral Sensory System:
translation
transduction
transmission
384
What are the 3 stages of the Peripheral Sensory System:
translation
transduction
transmission
385
What are the two components of all senses?
Central and peripheral
386
Accessory structures translate ___ to receptor cells
stimulus energy
387
Receptor cells transduce ___ as a biological response
generator potential
388
Output neurones such as afferent nerve fibres transmit information to the Central Nervous System in the form of ___
action potentials
389
The biological response in all sensory systems to their appropriate stimuli is an ___ one - a change in the electrical of the ___. This can occur because ___ have a ___
1. electrical
2. biological response
3. receptor cells
4. RMP
390
when a stimulus directly acts on the cell membrane of the receptor, what occurs?
ion channels are opened or closed.
391
the ___ acts on a ___ to produce a ___ in the form of a change in the ___.
1. stimulus
2. receptor cell
3. biological response
4. biological resting charge difference
392
in indirect receptor ion channels, the stimulus acts on the ___ of the receptor to activate a ___, the ___ of which acts on ___ to cause them to open or close. This will modulate the ___ compared to the ___, and thereby change the ___ between the inside and outside compared to the resting electrical charge difference between the inside and outside.
1. cell membrane
2. cascade of molecules
3. last
4. ion channels
5. movement of ions
6. rest state
7. electrical charge difference
393
What sensory systems act directly on the receptor ion channels?
Mechanoreceptors
394
What sensory systems act indirectly on the receptor ion channels?
chemoreceptors, photoreceptors, thermoreceptors, nociceptors.
395
Are receptor cells more or less polarized than neurons?
less polarized
396
Receptor cells are ___ with a ___ through them even when there are absent stimuli.
1. leaky cells
| 2. “standing current flow”
397
What is the process when a stimulus directly affects receptor ion channels?
stimulus; receptor cells; structural change in membrane; opening or closing of ion channels; conductance change (altered movement of ions); change in RMP
398
What is the process when a stimulus indirectly affects receptor ion channels?
stimulus; receptor cells; structural change in membrane; activated molecules; opening or closing of ion channels; conductance change (altered movement of ions); change in RMP
399
What is conductance change?
the altered movement of ions
400
What is the type of biological response generated in all sensory systems to their appropriate stimuli?
Electrical
401
What does an indirect effect on receptor ion channels involve acting on the cell membrane to activate?
a cascade of molecules
402
In what senses is the receptor not actually a separate receptor cell, but the specialized ending of a nerve fibre?
In the Skin senses (the Somatosensory system) and in Smell
403
In the Skin senses (the Somatosensory system) and in Smell, how is a train of APs generated?
Stimulus triggers specialized ending of nerve fibre (receptor surface), here, the Receptor Potential triggers a sequence of APs in the neuron, and the train of APs are transmitted along the length of the neuron - ultimately reaching the terminals where a chemical transmitter will be used to relay that information to the next neuron in the series, to the appropriate brain area.
Stimulus; receptor potential; modulation of APs in sensory neuron
404
In Hearing, Taste and Balance, how is a train of APs generated?
The receptor is a separate cell from the nerve fibre carrying information away.
The Receptor Potential triggers the release of chemical transmitter from the receptor cell to the nerve cell.
There, the transmitter will ultimately trigger a sequence of APs in the neuron, and the train of APs will be transmitted along the length ultimately reaching the terminals where a chemical transmitter will be used to relay that information to the next neuron in the series, to the appropriate brain area.
Stimulus; receptor potential; modulation of transmitter release from receptor cell; modulation of APs in sensory neuron
405
In Vision, how is a train of APs generated?
The receptor is a separate cell from the nerve fibre carrying information away, interposed between these two is a relay cell. So the Receptor Potential needs to be triggered or modulated for the release of chemical transmitter from the receptor cell to the relay cell.
This in turn triggers or modulates the release of chemical transmitter from the relay cell to the nerve cell.
There, the transmitter will ultimately trigger a sequence of APs in the neuron, and the train of APs will be transmitted along the length ultimately reaching the terminals where a chemical transmitter will be used to relay that information to the next neuron in the series, to the appropriate brain area.
Stimulus; receptor potential; modulation of transmitter release from receptor cell; modulation of transmitter release from relay cell; modulation of APs in sensory neuron
406
The information about the stimulus that sensory nerve fibres carry to the brain is what?
A train of APs
407
What can be said about the size of APs
They are invariant (stay the same)
408
Sensory systems vary what to describe the features of the stimulus they are sending to the brain.
The rate and timing of APs in the train of APs
409
Variation in the rate and timing of APs going to the brain is then used to how?
to code/signal different aspects of the stimulus.
410
what features can AP trains carry about a stimulus?
Constant/intermittent
Texture
Strength/intensity
411
when the sensory neuron produces APs throughout the duration of the stimulus, what does it signal to the brain ?
that the stimulus has been applied for the entire time (is constant).
412
when the sensory neuron only produces APs whenever the intermittent stimulus has been presented, what can the brain be signaled?
That the stimulus has been applied intermittently or varyingly.
413
What texture do closely spaced APs carrying information about?
Fine surface
414
What texture do widely spaced APs carry information about?
A rough surface
415
How can the texture of a stimulus be determined by a train of APs?
The spacing of the APs in the train give information about the stimulus texture
416
As we increase the stimulus strength, what happens to the number of action potentials we record from the sensory neuron ?
It increases
417
When stimulus are closely-spaced, what is the intensity/strength of the stimulus?
Strong/high-intensity
418
When stimulus are widely-spaced, what is the intensity/strength of the stimulus?
weak/low-intensity
419
What is stimulus quality about?
it's about that element that allows us to distinguish between different colours or different pitches of sound.
420
How can stimulus quality be transmitted to the brain?
through a nerve train of APs
421
How can stimulus quality be transmitted to the brain?
through a nerve train of APs
422
How can stimulus quality be distinguished? eg: pitch/frequency of sound
Because each individual receptor, that detects quality of a stimulus, and its nerve fibres won't respond to that full range we hear, but only to some part of the range. The different pitches will activate different receptors (or different combinations of receptors) and different nerve fibres, allowing us to hear different sounds.
423
What does hearing form in humans and many other animals?
The basis of social communication
424
What does hearing form in humans and many other animals?
The basis of social communication
425
What does audition dominate in the brain?
Temporal processing and spatial processing
426
What can audition give us information about?
What something is (we can recognized auditory objects.
| Where something is (we can localize objects based on auditory processing alone).
427
What is sound?
A wave of pressure travelling through an elastic medium (e.g., air, water) by mechanical disturbance (vibration) of the molecules of the medium.
428
How do sound waves begin?
First, a vibrating surface alternately causes compression and rarefaction of air molecules adjacent to the surface.
• In the regions of compression, the mechanical disturbance of air molecules causes a temporary increase in local pressure to above atmospheric pressure.
• Rarefaction causes a temporary decrease in local pressure below atmospheric pressure.
• Each individual molecule only moves a small distance before it bumps into a neighbour, which in turn bumps into another molecule.
• This creates a wave of compression and rarefaction (i.e., a wave of pressure changes) that, with time, travels away from the vibrating surface, through the process of compression and rarefaction of air molecules at more distant points away from the surface.
429
What is a wave of compression and rarifaction?
a wave of pressure changes
430
What does the mechanical disturbance of air molecules cause?
a temporary increase in local pressure to above atmospheric pressure.
431
What does rarefaction cause?
A temporary decrease in local pressure below atmospheric pressure.
432
What is compression?
When air molecules are drawn together
433
What is rarefaction?
When air molecules are drawn apart
434
Each individual molecule only moves a small distance, how does the sound wave continue?
it bumps into a neighbour, which in turn bumps into another molecule.
435
How does a wave of compression and rarefaction, with time, travel away from the vibrating surface?
through the process of compression and rarefaction of air molecules at more distant points away from the surface.
436
Does compression or rarefaction occur first?
Compression
437
What is a sound wave?
A variation in pressure with time
438
What does the speed of sound depend on?
the elasticity and the density of the medium in which the pressure changes are happening.
439
What is the speed of sound in air?
340m/s
440
What is the speed of sound in salt water?
approx. 1500m/s
441
Why does sound travel faster through denser mediums?
Because the particles are closer together in denser mediums, and so will collide much more quickly with each other, therefore the pressure wave will travel faster from the source of vibration.
442
What is frequency of sound?
Number of variations in pressure per second
443
What is the level or amplitude of sound?
The size of the pressure variations
444
What is frequency measured in?
Hertz (Hz) (pressure variation cycles / sec)
445
What kind of sound contains a low number of cyclical variations in pressure per second
low-frequency sound
446
What kind of sound contains a high number of cyclical variations in pressure per second
high frequency sound
447
In acoustic measurements, sound pressure or acoustic pressure is what?
the local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a sound wave.
448
In air, and water, what is sound measured in?
Microphone and hydrophone
449
What is the SI unit for pressure?
Pascal (Pa)
450
What measure of sound level is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. What units is it in?
SPL (sound pressure level), measured in decibels (dB) above a standard reference level.
451
What is considered as the threshold for human hearing?
The standard reference sound pressure in air or other gases is 20 μPa, (at 1 kHz).
452
The exact range of frequencies and levels depends on what factors?
Age
Exposure to loud sounds
Whether you've taken certain ototoxic drugs
Trauma to your head
453
The exact range of frequencies and levels depends on what factors?
Age
Exposure to loud sounds
Whether you've taken certain ototoxic drugs
Trauma to your head
454
What is the sound wave frequency range for human hearing?
20Hz to 20kHz (20,000Hz)
455
What is the sound wave intensity range for human hearing?
level: 10dB (intensity/loudness)
| Sound pressure level (SPL): 120 dB SPL
456
What is a pure tone?
A sound containing only one frequency of cyclical pressure variations, i.e., it is the simplest possible sound.
457
What is the main role of interneurons?
To do decide what to do and transfer the information from the sensory neurons to the motor neurons
458
State the electrical charge inside and outside of the neuron when an action potential is generated.
Positive inside and negative outside
459
what are complex sounds?
sounds that contain a complex pattern of pressure variations. A number of different pure tones can be combined to compose a complex sound.
460
How does the inner ear work in the opposite way to the combination of complex sounds?
it effectively decomposes a complex sound into the constituent simple sounds.
461
What puts back together auditory information to allow us to hear the sound as it is, and not as the individual components.
The brain
462
What are most sounds we hear?
Complex sounds: Combinations of simple tones of a range of different frequencies
463
The frequency content of a speech sound depends on what?
it depends on what needs to be said before and after that sound.
464
What is the phenomenon of co-articulation?
the way in which when you say a sound it depends on what other letters (sounds) occur before and after, because these letters influence the frequency content of the sound.
465
What are the 3 subsections of the human ear?
the external ear, middle ear & inner ear (cochlea).
466
What structures on the side of the head does the external ear consist of?
Pinna, tragus, concha
467
Where do the structures of the external ear lie?
Outside and around the ear canal (the external auditory canal)
468
What is the ear canal?
the tube that leads into the head and finishes at the eardrum (or tympanum).
469
Where does the middle ear start?
behind the tympanum (or eardrum), at the end of the ear canal.
470
What is the middle ear?
an air-filled cavity containing three ossicles called the malleus, incus and stapes and the Eustachian tube.
471
What is an ossicle?
A very small bone
472
What are the names of the 3 ossicles in the middle ear?
malleus, incus and stapes
473
Where does the Eustachian tube start and lead to?
it leads from the middle ear cavity down to the back of your mouth.
474
When you move your ear back and forth, what does the Eustachian tube do?
equalizes the air pressure on the two sides of the eardrum
475
What occurs when fluid and pus drains down the Eustachian tube?
Fluids accumulate in the middle ear
There is a feeling of fullness in your ears
Because of that fluid, the ossicles don’t move efficiently and everything sounds muffled as less energy from sounds is able to get to the inner ear.
476
What is another name for the inner ear?
The cochlea
477
What is the inner ear / cochlea?
a coiled fluid-filled tube, completely encased in bone except for 2 membrane-covered openings, the oval and round windows.
478
sound energy is ultimately converted into action potentials in the auditory nerve fibres by what part of the ear?
The cochlea
479
What carries the APs from the cochlea to the brain (carries information from the cochlea to the brain)?
Auditory nerve fibres
480
Where are the sensory receptor cells in the ear?
The cochlea
481
What are auditory receptor cells sensitive to?
movement
482
What is the path of sound energy from the world to the cochlea?
The world → External auditory canal → Tympanum → Malleus → Incus → Stapes → Cochlea
483
What is another name for the ear drum?
Tympanum
484
How are sound waves converted to movement?
The pressure waves of sound energy are converted into movement, when the pressure waves hit the eardrum and cause it to move back and forth as pressure increases and decreases in the sound wave.
This cyclical eardrum movement causes cyclical movement of the malleus, the first of the middle ear bones, which lies against the eardrum.
Movement of the malleus causes movement of the incus, which then causes movement of the last of these bones, the stapes.
Movement of the stapes against the oval window of the cochlea causes movement of the cochlear contents.
485
In the middle ear, how are the sound waves converted into movement?
The sound pressure waves cause rhythmic movement of the eardrum and then movement of the three middle ear bones in succession.
486
What does the external ear act as?
a funnel sounds into the ear canal and to modify sounds to help us localize them in elevation.
487
How does the external ear modify sound?
Because the external ear has a complex set of ridges and valleys, it also modifies how some sounds get into the ear canal, in a way that helps us identify whether a sound is in front of or behind us.
These modifications of sound waves are important for our ability to tell the elevation of a source of sound.
488
What happens when sound waves reach the middle ear?
they strike the tympanum, causing it to vibrate
489
What are the ossicles in the middle ear attached to?
The first of the ossicles, the malleus, is attached to the eardrum;
The second, the incus, is attached to the malleus; and
The third, the stapes, is attached to the incus.
Finally, the stapes is resting and held in place against the oval window membrane of the inner ear, so that as the stapes moves, it pushes into and out of that membrane and that causes movement of the contents of the inner ear.
490
What causes movement of the contents of the inner ear?
the stapes moving, pushing into and out of the oval window membrane, causing movement of the contents of the inner ear.
491
Why is the ear such a complicated system?
Because the inner ear is filled with fluid.
492
Why will the pressure waves directly striking the oval window mean that very little of that energy gets transmitted into the inner ear.
Because fluid molecules are harder to move than are the air molecules through which the sound pressure wave has been travelling.
493
Between the air in the external ear and the fluid in the inner ear, what is there?
an impedance mismatch
494
What is the most important role of the mammalian middle ear?
that it optimizes how air-borne sound energy is able to cause displacement of the fluids in the fluid-filled inner ear.
495
Is the impedance of cochlear fluid or air higher?
cochlear fluid
496
if sound waves were to directly strike the oval window, what would happen?
most sound would be reflected back from the inner ear.
497
How does the Middle ear match the impedance of air-borne sound energy to the fluid-filled cochlea?
by amplifying the sound energy so that now there is “more” force being applied against the oval window when the stapes moves it.
498
What is the small, pointy tip that the cochlea coils to called?
the apex
499
how many tubes does the cochlea contain?
three compartments winding together up the spiral coil
500
What, in the middle of the cochlea, runs all the way up the spiral coil?
the auditory nerve
501
What is the auditory nerve made of?
a number of nerve fibres that radiate out from the middle of the cochlea.
502
there is a row of what along the full length of the cochlea?
receptor cells
503
What does the Organ of Corti contain?
the receptor cells and the auditory nerve fibres carrying information to the brain.
504
What are the two types of receptor cells in the inner ear?
Inner hair cells
| Outer hair cells
505
What do Hair cells possess that stick out from their tops?
fine 'hairs' called stereocilia
506
what is the difference in electrical charge between the inside and the outside of a hair cell, with the inside being negative relative to the outside?
-60mV
507
What do all receptor cells have, even when there is no stimulus?
a "standing" current flow; there are ions flowing into and out of the cells.
508
what allows hair cells in the inner ear to have a standing current flow?
The stereocilia, which contain ion channels (pores for ions to flow through), so that when they are open, ions flow through the cell.
509
What is the RMP of hair cells determined by?
the intrinsic properties of the membrane, the distribution of ions across the cell, and the standing current flow.
510
If we modulate the ion channels in the stereocilia, what will this modulate?
the flow of ions into the cell, modulating the current flow into the cell, and thereby altering the RMP.
511
If the change is positive and the cell depolarizes enough across a hair cell membrane, what will happen?
the change to RMP will alter the release of transmitter from the hair cells to nerve fibres.
512
how do we get stereocilia to open up, alter current flow, and get depolarization, to increase the release of transmitter to the nerve fibres?
We bend them back and forth.
This happens when sound energy causes displacement (movement) of the eardrum which leads to movement of the ossicles in sequence, and finally the stapes moves into and out of the oval window membrane pushing into and pulling out of the fluid in the cochlea.
513
with one half-cycle of the pressure change of a simple sound wave, as the pressure increases, what happens?
the eardrum moves in, the stapes also moves into the oval window.
This displaces the cochlear contents away from the oval window and towards the round window.
514
with one half-cycle of the pressure change of a simple sound wave, as the pressure increases, what happens?
the eardrum moves in, the stapes also moves into the oval window.
This displaces the cochlear contents away from the oval window and towards the round window.
515
with one half-cycle of the pressure change of a simple sound wave, as the pressure decreases, what happens?
the eardrum moves out, the stapes also moves out of the oval window.
This displaces the cochlear contents towards from the oval window and away from the round window.
516
What does the vibration of the cochlear contents spread to.
base to apex of the cochlea.
517
what also travels through the fluids of the cochlear compartments?
"travelling waves" of cochlear movement
518
as the travelling wave of displacement of the cochlear partition and cochlear fluids travels along the cochlear partition, what happens?
It increases in size from the cochlear base to the apex.
| It then reaches a peak at some particular point and then rapidly ceases
519
What does the position of the peak of the cochlear fluid "travelling wave" depend on?
the frequency of the sound
520
Vibration of the cochlea partition at each point is most sensitive to a different frequency, why does this follow a systematic pattern?
because of the shape and mass of the structures of the middle compartment.
521
Where do high sound frequencies peak in the cochlear?
at the cochlear base
522
Where do low frequencies peak in the cochlear?
at the cochlear apex
523
in between the cochlear apex and the base there is a systematic grading of what?
frequency
524
he cochlea "decomposes" complex sounds into what?
their simple constituents.
525
Each spot on the ___ vibrates to a range of ___. It's just more ___ to one specific frequency.
1. cochlear partition
2. tone frequencies
3. sensitive
526
Each of the simpler constituents of a ___ cause ___ at one particular point along the cochlea, and that point varies with the ___ of that simple constituent.
1. complex sound
2. peak vibration
3. frequency
527
Why is stereocilia movement back-and-forth?
because partition vibration is up-and-down:
Sound causes the cochlear partition to vibrate up and down. Vibration of the cochlear partition up and down moves all the contents of the cochlear partition up and down as well.
Because of the fact that some of the structures of the Organ of Corti (like the tectorial membrane resting above the hair cell stereocilia) are "hinged" at different points compared to other structures, this means there is going to be movement of the hair cell stereocilia back and forth.
528
Why is stereocilia movement back-and-forth?
because partition vibration is up-and-down:
Sound causes the cochlear partition to vibrate up and down. Vibration of the cochlear partition up and down moves all the contents of the cochlear partition up and down as well.
Because of the fact that some of the structures of the Organ of Corti (like the tectorial membrane resting above the hair cell stereocilia) are "hinged" at different points compared to other structures, this means there is going to be movement of the hair cell stereocilia back and forth.
529
What do cyclical movement of the stereocilia cause?
cyclical opening and closing of the ion channels.
530
Movement of ___ in one direction opens the channels, allowing ___ to flow into the cell.
Since K+ is ___, the cell is gaining positive charge.
This ___ the cell, i.e., makes less negative the negative ___, even to the point of making it positively charged inside the cell.
This depolarization spreads down the hair cell and, at the base of the hair cell, causes the release of ___ which is stored there in vesicles.
1. stereocilia
2. potassium ions (K+)
3. positively charged
4. depolarizes
5. resting membrane potential
6. transmitter
531
The transmitter of hair cells can bind to receptors on the ___ and lead to the production of ___ in the nerve fibres. The action potentials are ___ to the brain to inform it about sounds.
1. nerve fibre
2. action potentials
3. transmitted
532
Vibration of the cochlea causes hair cells and then transmitters to do what?
become depolarized and release transmitters.
| Transmitters then activate the nerve fibres attached to the appropriate hair cells.
533
What is the process of converting a physical stimulus to a biological response in hair cells?
vibration of partition; receptor potential in hair cells; APs in nerve fibres.
534
The further the frequency from the frequency to which a hair cell are most-sensitive:
the louder the sound has to be to activate the receptor.
535
Hair cells are most sensitive to one specific frequency so:
they require the least amount of sound intensity at that frequency to be activated
536
Why is there a pattern to frequency sensitivity in nerve cells?
vibration activates the hair cells which activates the nerve cells, therefore we should see the same pattern of sensitivity in nerve fibres depending on where they get their input from
537
what frequency are nerves on the cochlear base most sensitive to?
high frequency
538
what frequency are nerves on the cochlear apex most sensitive to?
low frequency
539
What does the frequency sensitivity of a nerve depend on?
where from the cochlea the nerve fibre is getting input
540
why can people lose sensitivity to some frequencies but not others?
Because if you were to damage the apex of the cochlea, or the receptors at the apex or the nerve fibres from the apex, you’d only lose hearing sensitivity to low frequency sounds.
Conversely, if you were to damage the base of the cochlea, or the receptors at or nerve fibres from the base, you’d lose hearing sensitivity to high frequency sounds.
541
Why do more people suffer damage to hearing of high frequencies?
Because the base of the cochlear is more easily damaged.
542
How much of our brain contains neurons devoted to processing visual information?
almost 30%
543
How does light produce a biological response?
stimulus; receptor cells; structural change in membrane; activated molecules; ion channels open/close; conductance change (altered movement of ions); change in RMP
544
What are receptor cells in the eye called?
photoreceptors
545
What do photoreceptors convert to a biological response?
electromagnetic radiation
546
How is physical stimulus converted to a biological response in the eye?
by using a chain of activated molecules between stimulus acting on the cell and the biological response in the cell.
547
What is the biological response in the photoreceptors communicated to?
intermediate relay cells (bipolar cells).
548
what do intermediate relay cells (bipolar cells) communicate the stimulus information to?
nerve fibres (retinal ganglion cells)
549
What are the step for getting the visual information from the externa world to the retinal ganglion cells?
Stimulus; accessory structures (sensory/receptive zone on the neuron); specialized sensory cell; intermediate relay cell; neuron (retinal ganglion cell)
550
Where is information from intermediate relays cells communicated to?
retinal ganglion cells
551
what is the outermost layer of the eye?
the Sclera – a tough connective tissue whose collagen layer continues forward to form the transparent cornea.
552
what is intermediate layer of the eye?
the choroid - a vascular layer that continues to form a lumpy structure called the ciliary body.
553
What does the choroid continue to form?
the ciliary body
554
What is the ciliary body composed of?
muscles, processes, and ligaments arranged in a ring, from which are attached the muscles of the Iris, around the lens
555
what is the innermost layer of the eye?
The Retina
556
what is the surface in the eye that holds photoreceptors?
The Retina
557
which structure is suspended behind the Iris by the lens ligaments coming down from the Ciliary Body.
the Lens
558
The posterior chamber behind the lens inside of the eye is filled with a jelly-like fluid, called what?
Vitreous Humor
559
The anterior chamber in front of the lens inside of the eye is filled with a watery fluid, called what?
the Aqueous Humor
560
What are the roles of the accessory structures in the eye?
Refraction & Accommodation
Regulation of light entry into the eye
Reduction of spherical aberration
561
What are all the structures in the eye before the retina?
accessory structures
562
As light rays travel from their source through the air they will be ___ (___ and bent from their original path of travel) at any interface where the rays encounter a change in the ___ of the ___ through which they are travelling.
1. “refracted”
2. slowed down
3. density
4. medium
563
When does refraction occur?
whenever the light rays encounter a medium with a different density – i.e., wherever there is a change in density, not in a medium with a uniform density.
564
what are the two common ways in which refraction occurs in spherical lenses?
convex lens
| concave lens
565
Where does refraction occur in a lens?
at the front interface between the air and the lens and the back interface between the lens and the air.
566
When does refraction not occur?
When the medium is uniform
567
What type of lens causes divergence of light waves?
concave lens
568
Where is the focal point of a concave lens?
in front of the lens
569
Where is the focal point of a convex lens
behind the lens
570
What type of lens converges light rays?
A convex lens
571
Where are the three interfaces that experience refraction in the eye?
Air - cornea
Aqueous humor - lens
Lens- vitreous humor
572
What is the major site of refraction in the eye?
The air - cornea interface; it is the greatest density change
573
What type of lens is the lens in the eye?
a convex lens
574
the image that is formed at the back of the eye is ___. (Its’s our ___ that re-invert things so we don’t see the world like this)
1. Upside-down
| 2. brain
575
When do common refractive errors of the eye occur?
when the amount of refraction from the accessory structures does not match the eyeball length.
576
Short-sightedness, or Myopia, is when:
the amount of refraction of distant light rays is too much for the eyeball length.
When the light rays from any distant point are brought to a focus in front of the retina and then diverge again, before striking the retina.
Thus, the light rays are not at a focus when they the hit the retina and therefore the image would be blurred
577
How is myopia corrected?
By using a concave lens force to force the light rays to diverge a bit prior to striking the eye.
578
What is another name for myopia?
short-sightedness
579
What is a cause of myopia?
When the eyeball is shorter than normal. This means the light rays will not yet be brought to a focus when they hit the retina, blurring the image
580
What is another name for hypermetropia
Long-sightedness
581
What is hypermetropia?
When the amount of refraction of distant light rays is not enough for the eyeball length.
Then, light rays from any one distant point are not sufficiently refracted to be brought to a focus on the retina.
Thus, the light rays are not yet at a focus when they the hit the retina, blurring the image.
582
How can hypermetropia be corrected?
we can force the light rays to converge a bit prior to striking the eye using a convex lens, in other words we can gain some extra refraction prior to the eye.
This extra refraction prior to the eye will now force the light rays, for the amount of refraction in the eye at rest, to be brought to a focus a little more in front of their previous focal point - i.e., on the retina rather than "behind" it.
583
What is astigmatism?
When the horizontal & vertical light rays from the same object get focused on different parts of the retina.
This arises because of corneal irregularities which make light rays from different planes (horizontal vs vertical) focus on different parts on the retina.
584
What is accommodation?
When the lens adjusts its curvature to allow us to see near objects occurs through a gain in the refractive power of the lens.
585
What does accommodation occur through?
the contraction of a set of ciliary muscles in the eye that control the tension on the lens, allowing it to become more curved (and thereby gain extra refractive power)
586
lens becomes more ___ → accommodation
spherical (fatter)
587
With age, accommodation ___ and plateaus after ___
1. decreases
| 2. 50 years
588
* Explain how spectacle lenses are used to correct myopia
Myopia is when the refraction of distant light rays is too much for the eyeball length. Here, light waves from any one distant point are brought into focus in front of the retina and then diverge again before striking the retina.
A concave spectacle les will force the light rays to diverge slightly before striking the eye. This forces them, for the amount of refraction in the rest of the eye, to be brought to focus further back than before, providing the desired divergence to see clearly at distance.
589
What part of the eye regulates light entry?
the iris
590
Why does the iris increase or decrease to control the amount of light entering the eye?
1. To prevent saturation of photoreceptors in bright light and allow maximum light capture in dim light.
2. To reduce spherical aberration (which occurs with all lenses) - where the outer parts of the lens distort the image because of too much refraction.
591
What does the light regulation of the iris occur through?
the contraction of the muscles that make up the iris
592
Why do our lenses accommodate?
to see near object in sharp focus
593
Why do your pupils constrict?
to reduce light saturation from the near object and to reduce the spherical aberration distortion of the image
594
Why do your eyes converge?
so that both eyes are focusing on the same object
595
Automatic reflexes of light regulation in the eye are triggered by what?
the brain due to the defocusing (the "blurriness") of the image as the object is closer, and these changes haven’t yet occurred.
596
What do photoreceptors do?
detect physical energy to produce a biological response.
597
What is the retina?
a highly layered structure of cells with the photoreceptors (called rods and cones) located at the back, furthest from the path of light.
598
Where on the retina are there no photoreceptors - so light rays falling on that region are not detected?
the blind spots
599
In species that hunt at night, there is often a ___ layer behind the ___, so that light rays which are not captured by the receptors in their first pass through the eye to the ___ can be reflected back for a second try at capturing them.
1. reflective
2. photoreceptors
3. retina
600
What are rods for?
dim vision
601
How many types of rods are there?
1
602
how may types of cone cells are there?
3
603
What are cone cells for?
for daylight vision and allowing colour discrimination
604
What gives cones and rods their names?
the shape of the structure of the outer part of the receptors
605
What does the outer segment of photoreceptors contain?
the molecules that can absorb light energy.
606
What part of a photoreceptor connects the outer and inner segments?
the cilium
607
What does absorption of light energy set off?
a train of chemical reactions
608
The molecules involved in the cascade are found where in a photoreceptor?
the outer segment.
609
where are transmitter located to be released to relay cells?
the end of the inner segment
610
Where are intermediate relay cells found in relation to photoreceptors?
below the synapse of the photoreceptor
611
photoreceptors undertake ___ to relay information about ___ to the ___ in the series.
1. chemical transmission
2. light
3. next cell
612
In photoreceptors, what 2 components does the visual pigment contain?
a chromophore and a protein opsin
613
What does a chromophore do in the visual pigment of photoreceptors?
absorbs light
614
when is a protein opsin activated?
when the chromophore absorbs electromagnetic energy.
615
what does a protein opsin hold in a particular way?
a chromophore
616
In both rods and cones, what is the chromophore (the light-absorbing molecule) called?
11-cis-retinal
617
What is 11-cis-retinal derived from?
vitamin A; that is why vitamin A deficiency can lead to certain forms of blindness.
618
What about the protein opsin differs between rods and cones, as well as between the different types of cones?
the structure of the protein Opsin that holds the chromophore in place for light absorption.
619
In rods, what is the visual called?
Rhodopsin
620
Cones use several types of cone visual pigments (all using 11-cis-retinal as the chromophore), differing only in the opsin type. What does this allow?
it allows each type of cone visual pigment to absorb light best at a different wavelength, forming the basis of our colour vision.
621
The receptors are distributed in ___ across the ___.
1. specific ways
| 2. retina
622
Rods and cones are both absent at a spot at the back of the eye, what is this spot called?
The blind spot
623
___ are not ___ distributed across the retina.
1. Rods and cones
| 2. uniformly
624
Where are cones highly concentrated?
the fovea (their numbers are very low elsewhere)
625
Rods are totally absent at the ___ - their numbers are greatest ___.
1. fovea
| 2. beside the fovea
626
The numbers of cones ___ as you move to the edges of the eye but, except at the ___, they are always present at ___ than cones.
1. decreases
2. fovea
3. much higher numbers
627
The brain ___ its guess of what we what should be in a ___
1. "interpolates"
| 2. blind spot
628
* Outline why we don't see blank spaces in our view:
When we look at the world, we don't see blank spaces because our brain fills in that hole in our vision. It makes a guess based on what is around that blank hole in our vision, and based on our experience of the world, what might be a reasonable thing to continue across the blank hole. Therefore, the brain interpolates into the empty space in our vision so that people don't have holes in their faces, or objects appear to be incomplete.
629
In rods the overall structure called Rhodopsin consists of what?
An opsin and 11-cis-retinal (chromophore)
630
The wavelength sensitivity of photoreceptors is due to what?
how the opsin holds the chromophore
631
The way in which the chromophore is held will determine what?
the wavelength of light it will absorb best.
632
There are 3 ___, each with their own ___ which allows each type of cone's ___ to absorb light best at a different ___. This forms the basis of ___.
1. cones
2. opsin
3. visual pigment
4. wavelength
5. colour vision
633
All ___ have the same ___, so they all show the ___
1. rods
2. opsin
3. same wavelength sensitivity
634
What are the 3 colours of cones?
blue, green, red
635
what are metabotropic receptor?
G-protein coupled receptors (GPCRs).
636
Visual pigments are what type of receptors?
G protein coupled receptors (GPCRs) that come from a common superfamily of such metabotropic (G protein coupled) receptors.
637
when a GPCR is activated by an appropriate signal, what is it capable of?
binding and activating a G protein and that can set off a cascade of intracellular reactions.
638
In visual pigments the signal is what?
the energy in the electromagnetic radiations of light.
639
What is the binding site for the signal of energy in electromagnetic radiations of light?
he chromophore 11-cis-retinal
640
When a visual pigment is activated, what does it activate?
a G protein.
641
Once light activates the ___, then the activated visual pigment must activate ___. That in turn will activate a ___, the final one of which is a molecule that breaks down a molecule called ___.
1. visual pigment
2. a G protein.
3. sequence of activations
4. cyclic GMP
642
Light activates a molecular cascade that results in what?
the breakdown of a molecule called cyclic GMP into its non-cyclic form.
643
Breakdown of cGMP changes the flow of what?
Na+ and Ca2+ ions into the receptors.
644
A change in the flow of current from the ___ will produce the ___ in photoreceptors that signals the absorption of the ___.
1. resting current flow
2. electrical response
3. stimulus light energy
645
Breaking down cyclic GMP produces what?
the biological electrical response.
646
Cylic GMP (cGMP) is actually like a ___—it holds open channels that allow the ___ into the cell.
1. gate molecule
| 2. flow of sodium ions (Na+) and calcium (Ca2+) ions
647
When cGMP is broken down, it will prevent the flow of these ions into the receptors. This results in what?
A change in the flow of current compared to the resting flow.
648
In photoreceptors, the change in ___ from the resting state current flow will alter the ___ of the cell - it will change the ___
This produces a changed electrical state in ___ because they have absorbed the stimulus light energy.
1. current flow
2. resting membrane potential
3. resting electrical state.
4. photoreceptors
649
What are the steps for receptor cells signal the absorption of light stimulus energy?
light stimulus energy; activated rhodopsin; activated G-protein; activated enzyme (PDE); Cyclic GMP broken down to GMP; change in RMP of cell; signals biological response
650
What does the cascade system in photoreceptors allow?
amplification of the signal
651
Why does vision use a complex cascade system that requires 3 different molecules
because the cascade allows amplification of the signal.
652
A single photon of light can activate:
only 1 Rhodopsin molecule
653
Only 1 ___ is activated by a light stimulus, but in the ___, this can activate 10s
of the next molecule and each of those can activate 100s
of the next molecule and so on.
Thus the last molecule can alter the ___ of ___ of the cGMP molecule and that will affect the flow of a large amount of ___ into the cell.
1. Rhodopsin molecule
2. cascade of molecules
3. cyclic status
4. millions
5. current
654
In a ___, a light ray has to activate the ___ and that has to activate the cascade, and the last molecule has to break down ___, and that has to result in a change in the ___, to change the resting electrical state, to signal the presence of ___.
1. amplification cascade
2. visual pigment
3. cGMP
4. normal (resting) current flow
5. the stimulus
655
The amplification makes it much more likely that a single photon of light can result in what?
a significant enough biological response for all this to happen and for information to go to the brain.
656
A large change in the ___ makes it much more likely that there will be a ___ in the electrical properties of the ___, to be able to produce ___ to the next cell, eventually resulting in ___ in ___ that will carry that information to the brain.
1. current flow
2. sufficient change
3. photoreceptor
4. information flow
5. action potentials
6. nerve fibres
657
In signalling from a neuron to another cell, one mechanism involves ___ (GPCRs) which bind ___ to activate a ___.
The active G protein in turn activates secondary molecules, called ___.
This allows for ___ of the signal.
1. metabotropic receptors
2. transmitters
3. G protein
4. second messengers
5. amplification
658
* Outline the steps of the amplification cascade and briefly explain why it is important:
A light ray has to activate the first visual pigment molecule, which activates a seconds molecule, and that third molecule finally acts on cyclic GMP (cGMP), the one which controls current flow in the receptor cell. cGMP changes the resting current flow, that in turn changes the resting electrical state to signal the presence of a stimulus.
Amplification results in a large change in the current flow, making it much more likely that there will be s a sufficient change in the electrical properties of the photoreceptor, to be able to produce information flow to the next cell, eventually resulting in APs in nerve fibres that will carry the information to the brain.
659
During daylight there is a lot of background bright light.
If light rays set off the cascade we described before, and break down cGMP to close off channels, why is it we can see anything at all in the daylight?
through light adaption
660
What does light adaptation allow?
it allows photoreceptors to cope with constant background (daylight) light.
661
In light adaption, the cell simply produces more ___ and does so faster, in ___ than in dark conditions.
By doing this, the ___ can continuously work against the break down of cGMP caused by the ___.
1. cGMP
2. bright daylight conditions
3. photoreceptors
4. background light.
662
As a bright light is kept on constantly, what happens to the electrical response in the photoreceptor?
the electrical response declines with time and the membrane potential returns to rest.
663
All sensory systems show a process of adaptation, what is this?
a decline in the response of the system even though the stimulus is maintained constantly.
664
What is the mechanism whereby we can allow our vision to operate in bright daylight?
Adaptation to a constant light stimulus,
665
The ___ has developed this compensatory mechanism (light adaption) whereas ___ hasn't, despite the fact that our lives are surrounded by noise, most likely to do with ___.
Constant background annoying noise has really been with us only since the Industrial Revolution. Far too soon in our history for any___ - and evolution doesn't work to create ___ to take care of environments that may exist in the future!
1. visual system
2. hearing
3. evolution
4. evolutionary compensation
5. mechanisms
666
Does light adaption work better in cones or rods?
Light adaption works better in cones than rods
667
The process of light adaptation occurs in both ___ – i.e., both produce more ___ and do so faster, in ___ than in dark conditions.
1. rods and cones
2. cGMP
3. bright daylight conditions
668
The light-induced breakdown of cGMP in rods is how much more efficient than in cones?
100 times more efficient
669
Even though ___ are producing more cGMP and doing so faster in bright daylight conditions, the efficient ___ causes cGMP breakdown as fast as cGMP is being produced.
Rods are not functional in signalling light from objects when there is ___ – during the day time.
Daytime vision is therefore dependent solely on ___.
1. rods
2. light absorption cascade
3. bright background light
4. cones
670
What type of receptors are foveal vision?
cones
671
What type of receptors are non-foveal vision?
rods
672
What is the difference between the direction of gaze of rods and cones? Why?
Cones are activated by axial gaze vs Rods universal gaze
Why: Location of receptors across retina: Cones are found almost only at the fovea so you have to look directly at an object to get cone vision into play (that’s why you need to look directly at an object to see it’s colour).
673
What is the difference between the colour detection of rods and cones? Why?
Cones are wavelength sensitive
Why: Type of protein opsins: Rods only have one type of opsin, cones have one of three different opsins, each of which absorbs light best at a different wavelength
674
What is the difference between the absolute sensitivity of cones and rods? Why?
Rods are more sensitive.
Why: Efficiency of cascade mechanisms: Rods have a more sensitive cascade that breaks down cGMP, so they are useful in very low light levels – e.g., at night. However, this sensitivity means they become non-functional when there is bright background light – sunlight.
675
What is the difference between the ability of rods and cones to signal fast events? Why?
Cones signal fast events, rods slow
Why: Recovery rate to rest: The responses in cones is less sensitive but faster recovering. So they can signal a second event occurring soon after the first. Rods are slow to recover to rest, so they are still responding to the first event when a second fast event occurs.
676
Information about what we see has to be transmitted to the brain by what?
retinal ganglion cells (RGCs)
677
What defines the photoreceptors that influence a retinal ganglion cell?
the receptive field of the RCG
678
each RGC only gets information from a ___ set of ___. This set makes up the ___ of that cell.
1. finite
2. photoreceptors
3. Receptive Field (RF)
679
the region of the world from which light can act on photoreceptors to influence that specific retinal ganglion cell is what?
the receptive field of a RGCs
680
What are the parts of a RGCs RF?
The RF centre and the RF surround
681
How do the the receptors of the RF centre send information to a RCG?
via the direct pathway to the RGC
682
How do the receptors of the RF surround send information to a RCG?
via the indirect pathway to the RGC.
683
What are the two pathways of the concentric receptive field of a RGC?
There is a circular set of receptors that send information via the direct pathway to influence the train of APs that the RGC will send to the brain.
This is surrounded by another circle of receptors that send information via the indirect pathway to influence the train of APs that the RGC will send to the brain.
684
the size of the RF varies between RGCs according to what?
where they are located across the retina.
685
The RFs are smallest for RGCs getting information from the ___.
As you move away from the ___, RGCs getting input from receptors located away from the retina have ___.
1. fovea of the retina
2. fovea
3. progressively larger RFs
686
What does it mean if a RF size is large?
.it means the RGC is getting input from a large circle of photoreceptors.
687
What does it mean if the RF size is small?
it means the RGC is getting input only from a small circle of photoreceptors.
688
What is acuity?
The ability to tell fine details
689
small RFs in the RGCs allow:
high visual acuity.
690
Each RGC is getting input from many photoreceptors which:
signal a different element of one stimulus or even from different stimuli.
691
RGCs with large RFs are summing up information across a:
large number of photoreceptors.
692
Large receptive fields can signal ___ at the expense of ___.
1. the presence of an object/ detection of an object
| 2. poor visual acuity.
693
As RF size increases:
visual acuity should decrease, and therefore visual acuity should vary across the eye.
694
Where is day-time visual acuity the highest in the retina? Why?
the fovea
| Why: because RGCs in the fovea have the smallest RFs
695
Cones are much less ___ than rods and the fovea contains only ___.
Thus when light levels are low, there isn’t enough ___ to activate cones and therefore the RGCs getting input from the cones will be silent.
However, even at night, ___ is highest in the region where functional RGCs have the ___ – now beside the fovea.
1. sensitive
2. cones
3. light
4. acuity
5. smallest RFs
696
What part of the eye has the highest visual acuity at night?
The region beside the fovea (the para-fovea)
697
what photoreceptors does foveal vision have?
only cones
698
what photoreceptors does non-foveal vision have?
rods and cones
699
Why do foveal and non-foveal regions of the retina have different directions of gaze?
because cones have axial gaze (the fovea), and rods on the periphery have universal gaze. This is due to the location of the receptors across the retina.
700
Why do foveal and non-foveal regions of the retina have different colour detection?
Because cones (in the fovea) are wavelength sensitive, and rods are not, this is due to the type of protein.
701
Why do foveal and non-foveal regions of the retina have different absolute sensitivity?
Because rods are more sensitive than cones (therefore the periphery is more sensitive than the fovea to light). This is because of the difference in the efficiency of the cascade mechanisms of the two photoreceptor types.
702
Why do foveal and non-foveal regions of the retina have different in their ability to signal fast event?
Because cones can signals events faster than cones. This is because cones have a faster recovery rate after being exposed to light.
703
Why do foveal and non-foveal regions of the retina have different acuity.
Because the size of the RFs of RGCs in the fovea are smaller than the size of the RFs of RGCs in the periphery.
704
What do small RFs allow us to do?
Discriminate between fine details of objects
705
What are the 2 pathways RGCs receive information about light from?
the direct and indirect pathways
706
What kind of shape are receptors arranged in?
Circular shape
707
The centre and the surround of the ___ in a retina have ___ effects on the ability of the RGCs to produce ___.
1. receptive fields
2. antagonistic (opposing)
3. APs
708
Stimulation of the region of the retina that makes up the centre of the RF of the RGC produces one type of response and stimulation of the region of the retina that makes up the surround produces:
the opposite response
709
In about ___ of the RGCs, activating the photoreceptors that make up the RF Centre produces excitation and activating the photoreceptors that make up the ___ produces the opposite effect of ___.
1. 50%
2. RF Surround
3. inhibition
710
what is the opposite of excitation?
inhibition
711
What is a RGC excited by the photoreceptors making up the centre of its RF called?
an ON Centre RF
712
In the remaining ___ of RGC receptors that are not an ON Centre RF, the centre of their RF is ___ by photoreceptors, therefore it is called a: ___.
1. 50%
2. inhibited
3. OFF Centre RF
713
What happens when you activate a OFF Centre RF
the RF centre turns the cell OFF
714
In RGCs with "ON" Centre RFs, stimulating the photoreceptor(s) that make up the RF Centre of that RGC causes what?
the RGC to become excited and produce APs.
715
Stimulating the photoreceptor(s) that make up the RF surround of an ON centre RGC causes what?
the RGC to become inhibited and cease producing APs.
716
During the period of light stimulation of the RF centre of an ON centre RGC, there is an:
increase in the number of APs in the RGC
717
During the period of light stimulation of the RF surround of an ON centre RGC, there is a:
decrease in the number of APs in the RGC.
718
In RGCs with "OFF" Centre RFs, stimulating the photoreceptor(s) that make up the RF Centre of that RGC causes:
the RGC to become inhibited and cease producing APs.
719
Stimulating the photoreceptor(s) that make up the RF surround of a OFF centre RGC causes:
the RGC to become excited and produce APs.
720
During the period of light stimulation of the RF centre of a OFF centre RGC, there is a:
decrease in the number of APs in the RGC
721
During the period of light stimulation of the RF surround of OFF centre RGC, there is an:
increase in the number of APs in the RGC.
722
In RGCs, the centre and ___ produce ___ – light in one region activates the cell while light in the other region ___ the cell.
1. surround
2. opposing effects
3. inhibits
723
Normally each cell will be faced with a ___ which activates both ___.
Hence normally you have each RGC getting both ___ influences.
1. stimulus
2. centre and surround
3. excitatory and inhibitory
724
If excitation is greater than inhibition:
the cell will be able to produce APs to send to the brain.
725
If inhibition is greater than excitation:
the cell will be reduce the APs it sends to the brain.
726
Whether the cell will be able to signal ___ to the brain will depend upon the ___ it receives – the strength of the light falling on the excitatory component of the RF vs the strength of the light falling on the ___ of the RF.
1. APs
2. strength of the excitation versus the strength of the inhibition
3. inhibitory component
727
The RGC is going to send information to the brain that will depend on:
how much light is causing excitation (through one part of the RF) versus how much light is causing inhibition (through the other part of the RF).
728
RGCs are interested in the ___ between the amount of light in one part of their RF and the amount of light in the
___.
1. contrast
| 2. other part of their RF
729
If light intensity is greater in the inhibition RF than the excitation RF, what will the RGC cell do?
Cease producing APs
730
If light intensity is greater in the excitation RF than the inhibition RF, what will the RGC cell do?
Start producing APs
731
The greater the difference of light intensity between the excitation and inhibition region:
the greater the amount of APs (in excitation)
| the lesser the amount of APs (in inhibition)
732
In both ___ cases, the RGC is going to send information (in the form of APs) to the brain that will depend on how much light is causing excitation (through one part of the RF) versus how much light is causing ___ (through the other part of the __.
1. ON centre and OFF centre
2. inhibition
3. RF
733
RGCs are interested in the contrast between the amount of light in one part of their RF and the amount of light in the other part of their RF, therefore what are examples of how this is used in visual processing?
It distinguishes a dark patch from a lighter patch. And you can use this ability to identify the edges of an open door, the edges of a letter on a printed page!
734
what do opposing centre and surround effects allow?
Signalling of contrast
735
cones show wavelength ___ in their responses – each cone is ___ for one particular ___.
1. sensitivity
2. selective
3. wavelength
736
information about “colour” is preserved by:
RGCs
737
the RF of the RGC has a ___ where light in the ___ region that makes up the RF centre produces one effect and light in the ___ produces the opposite effect.
1. centre-surround antagonistic organization
2. retinal
3. RF surround
738
Many RGCs have their centre and surround produce their appropriate effects only to particular ___ of light – other wavelengths of light ___ at all. Thus, these RGCs are said to show ___ in their ___.
1. wavelengths
2. do not produce any effect
3. wavelength selectivity
4. centre-surround RF organization
739
In the wavelength ___, the wavelength that produces effects in the centre is ___ the wavelength that produces the ___.
1. selective RFs
2. different from
3. opposing effects in the surround
740
In the wavelength ___, the wavelength that produces effects in the centre is ___ the wavelength that produces the ___.
1. selective RFs
2. different from
3. opposing effects in the surround
741
Wavelength sensitive retinal ganglion cells pair very particular wavelengths in their receptive fields. What are the 2 colour pairings?
Red/green
| Blue/yellow
742
Wavelength sensitive retinal ganglion cells pair very particular wavelengths in their receptive fields. What are the 2 colour pairings?
Red/green
| Blue/yellow
743
How many different types of wavelength sensitive RGC combinations are there? What are they?
```
8:
Red ON centre
Green ON centre
Red OFF centre
Green OFF centre
Blue ON centre
Yellow ON centre
Blue OFF centre
Blue ON centre
```
744
How do RGCs show wavelength selectivity?
The centre and surround produce their effects only to particular wavelengths of light.
745
Predict the excitation and inhibition of a stimulated red ON-centre retinal ganglion cell.
Excited by red in centre, inhibited by green in surround.
746
Predict the excitation and inhibition of a stimulated yellow OFF-centre retinal ganglion cell.
Excited by blue in surround, inhibited by yellow in centre.
747
The axons of the retinal ganglion cells run together as ___ from the ___ to the ___ in the forebrain.
1. The Optic Nerve
2. eye
3. Thalamus
748
The thalamus is an ___ to the ___ for almost all sensory systems
1. obligatory relay
| 2. cortex
749
The thalamus selects what ___ is allowed to flow on to cortex and therefore selects what ___ will come into our ___.
1. sensory information
2. aspects of the world
3. consciousness
750
What type of structure is the thalamus?
a collection of nuclei (a brain collective of cell bodies) that receive input from other axons and send their outflow axons to some other structure or structures, with each nucleus doing something different.
751
What nucleus in the thalamus is important for the relay of visual information?
the Lateral Geniculate Nucleus, (LGN).
752
The LGN is a layered structure; how many layers does it consist of?
6
753
How many inner layers are there in the LGN; what are they called?
2 inner layers called MAGNOCELLULAR layers.
754
How many outer layers are there in the LGN; what are they called?
4 outer layers called PARVOCELLULAR layers.
755
What layer of the LGN consists of large cells?
The Magnocellular layers
756
What layers of the LGN consists of large cells?
The Magnocellular layers
757
What layers of the LGN consists of small cells?
the Parvocellular layers
758
Each LGN receives input from how much of each eye?
Half of both eyes
759
Each LGN receives input from how much of each eye?
Half of both eyes
760
In species with ___ (like humans), the LGNs receive ___ from RGCs from the inside half of each eye that cross over to join the ___ of the other eye.
1. frontally-directed eyes
2. axons
3. RGCs from the outside half
761
What parts of each eye does the LGN receive input from?
The inside half of one eye, and the outside half of the other
762
What is the purpose of putting together the axons from the inside half of one eye and the outside half of the other eye?
to keep together information from the same side of the world.
763
What does the LGN is start the process of?
binding together information from the two eyes, about the same objects.
764
Each ___ layer receives inputs from ___ eye.
1. LGN
| 2. only one
765
Although the inputs from the two eyes are all about the same object in the world, and about similar parts of the same object: why are we not yet putting them together at this stage of the brain processing?
Because each LGN layer only receives input from one eye
766
Although the inputs from the two eyes are all about the same object in the world, and about similar parts of the same object: why are we not yet putting them together at this stage of the brain processing?
Because the inputs from each ee
767
* Describe the structure of the LGN:
The LGN is a layered structure consisting of 6 layers of cells. There are 2 inner layers called the magnocellular layers and 4 outer layers called parvocellular layers, The magnocellular layers contain large cells and the parvocellular layers contain small cells.
768
What is the inside half of each eye called?
The nasal half
769
What is the outside half of each eye called?
The temporal half
770
On the way to the brain, in species with frontally-directed eyes, the axons from RGCs from the nasal half) of each eye cross over to join the RGCs from the temporal half of the other eye. Where does this occur?
the Optic Chiasm
771
Where is the Optic Chiasm located?
the base of the brain.
772
In humans, what % of RGCs from one eye cross over to the other side?
about 50%
773
The left LGN in the brain gets input from where?
the LEFT halves of both eyes
774
The right LGN in the brain gets input from where?
the right halves of both eyes.
775
Why are the inputs of the left halves of each eye kept to the left LGN?
This is because an object to the right of your fixation point (at which you are directing your fovea) will form images on the left half of each eye.
Keeping nerves from these two parts together keeps together information about the same part of the world (in this case, the world to the right of the fixation point).
776
What is the purpose of the Optic Chiasm?
to keep together information from the same parts of the visual field.
777
In species with eyes on the ___, the crossing over at the ___ still keeps together information from the same parts of the ___
ALL the RGC axons from an eye cross over to the LGN on the ___ of the head.
1. side of the head
2. Optic Chiasm
3. visual field.
4. other side
778
In species with side-facing eyes, what one eye sees is ___ of what the other eye sees – whereas in species with frontally-directed eyes, the middle part of our visual field sends light rays to ___.
So in species with front -facing eyes, it makes sense to put together the information from the left half of one eye and the ___ of the other eye.
In contrast, in species where each eye is independent of the other eye, it doesn’t make sense to put together the information from half of one eye and the information from ___.
1. independent
2. both eyes
3. right half
4. half of the other eye.
779
what are the two broad classes of RGCs called?
M cells
| P cells.
780
What percentage of RGCs are M cells?
10%
781
What percentage of RGCs are P cells?
90%
782
P class RGCs have:
small cell bodies and their dendrites don't spread very widely.
783
M class RGCs have:
large cell bodies and their dendrites spread very widely.
784
M cells have a ___likelihood of getting input from a ___ of the retina (effectively a larger number of ___) than ___.
1. greater
2. larger region
3. photoreceptors
4. P cells
785
M cells have ___ RFs
| P cells have ___ RFs
1. larger
| 2. smaller
786
P class RGCs are the ones which will be ___. Not all P class RGCs, but never ___ RGCs.
1. wavelength sensitive
| 2. M class
787
In species with eyes on the ___, all the RGC axons from an eye cross over to the ___ on the other side of the head. In such species, ___ ___ light from crossing over for all practical purposes. What one eye sees is ___ of what the other eye sees.
1. side of their head
2. LGN
3. the nose and other parts of the face
4. block
5. independent
788
* contrast the 2 broad classes of RGCs
Cell bodies of the M and P class RGCs and how the dendrites (where neurons receive the majority of their inputs) spread across the retina. P class RGCs have small cell bodies and their dendrites don't spread very widely. M class RGCs have large cell bodies and their dendrites spread very widely.
This means M cells have a greater likelihood of getting input from a larger region of the retina (effectively a larger number of photoreceptors) than P cells. M cells will have large RFs and P cells will have smaller RFs.
789
From the LGN in the thalamus, information flows to where?
the visual cortex (V1)
790
In primates, the visual cortex (V1) is a huge area that takes up how much of the cerebral cortex?
20%
791
V1 is the ___ and receives ___ directly from the ___.
1. primary visual cortex
2. inputs
3. lateral geniculate nucleus.
792
Although called the primary visual cortex, and critical to perception, V1 is not the:
only visual cortex area to get direct input.
793
Area MT (___) also receives direct input from ___ and other nuclei of thalamus.
1. Middle Temporal or V5 in the numbering system
| 2. LGN
794
The alternate pathways in visual processing, especially to __, from thalamus to ___ have been proposed to be responsible for the phenomenon of ___, where people who have had damage to ___ and are not able to report any ___, can still navigate their way around a complex environment with obstacles.
It's consistent with the fact that cells in MT appear to be selective for ___ and are not well modulated by object features - and people with Blindsight can't describe the object but can report, even though unconsciously, ___ and can avoid obstacles in the environment.
1. MT
2. cortex
3. Blindsight or unconscious perception
4. V1
5. conscious perception of objects
6. motion or object location
7. object motion
795
The cortex is a:
layered structure, of layers of different types of cells stacked on top of each other.
796
why do different layers of the cortex look different when dyed?
because the chemicals used are not dispersed uniformly between the different cells of the cortex
797
what is white matter in the cortex?
the collection of axons running from cell bodies in other brain regions to this cortex or the collection of axons running from cell bodies in this cortex to other brain regions
798
what is the isocortex?
the major part of the neocortex, the evolutionarily newest part of the brain; isocortex is distinguished by its layered structure of many cells
799
Each layer in the isocortex has a:
characteristic set of cells and connections.
800
What is layer 1 of the isocortex?
a dense mat of fibers, which spread back and outward across the surface of the cortex. Many of them carry specialized transmitters, such as noradrenaline and dopamine from the hindbrain, penetrating deeper layers to distribute them throughout the cortex.
801
what is layer 2 of the cortex?
a layer that consists of small pyramidal cells and small inhibitory cells, which act in local circuits of neurons to process inputs.
802
what is layer 3 of the cortex?
the layer that has larger and more numerous pyramidal cells, which send excitatory outputs to other parts of the cortex, either nearby or in the opposite hemisphere. Basket cells and other inhibitory cells in layer 3 spread inhibition to neighboring cells, as part of cortical processing.
803
which layer of the isocortex is the input layer?
layer 4
804
what is layer 4 of the isocortex?
The main recipient of sensory fibers coming from the thalamus. Its granular appearance is due to the concentration of small stellate cells. In specialized sensory areas, the spiny stellate cells of layer 4 are organized into a number of sub-layers
805
What is layer 5 of the isocortex?
Layer 5 contains the largest pyramidal cells, which send their axons to regions outside the cortex, such as the striatum and spinal cord.
806
What is layer 6 of the isocortex?
Layer 6 has small pyramidal cells that project to part of the thalamus, which in turn supplies inputs to the cortex. This arrangement completes a feedback loop which regulates incoming thalamic activity.
807
What are pyramidal cells?
a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract.
808
What layer of the visual cortex receives the input from the LGN?
Layer 4
809
Information from layer 4 is relayed to Layers II and III which are:
integrate different types of input and from closely adjacent points in the same cortex (V1), and integrate inputs from across V1.
810
What are the integration layers of the visual cortex?
Layers 2 and 3
811
The integrated information from layers 2 and 3 of the visual cortex is then relayed to:
Layers V and VI; which are output layers to sub-cortical sites and to other cortical regions (like motor cortex, to produce a response).
812
What are the output layers in the visual cortex?
layers 5 and 6
813
Where do alternating eye inputs in input layers come together?
in the upper integrative layers.
814
The ___ of the eye inputs from the ___ is maintained in the ___ of V1 but then the inputs from the two eyes are ___ when they flow from the input layers to the ___
1. segregation
2. LGN
3. input layers
4. merged
5. upper integrative layers.
815
The V1 ___ can be thought of as consisting of ___ of cells next to each other. In this layer, the inputs from the two eyes are ___.
From here information flows to the ___ - here, finally, inputs from the ___ are brought together.
1. input layer
2. adjacent small columns
3. kept separate
4. upper layers
5. two eyes
816
* Outline the flow of information through the layers of the primary visual cortex:
As a simplification, layer 4 receives the input from the LGN. This information is relayed to layers 2 and 3, which are integrate different types of input and form closely adjacent points in the same cortex (V1) and integrate inputs across V1.
This integrated information is then relayed to layers 5 and 6 which are output layers to sub-cortical sites and to other cortical regions (like motor cortex, to produce a response).
817
Responses of neurons in the lateral geniculate nucleus are very similar to those of:
retinal ganglion cells.
818
The ___ in the LGN have ___ and the centre and surround produce ___ effects.
1. neurons
2. centre-surround receptive fields
3. opposing
819
At the LGN the opposing effect of the surround on the ___ is ___ than the opposing effect of the ___ on the centre at the___.
Thus, the LGN doesn’t ___ that it gets from the retina.
1. centre
2. stronger
3. surround
4. retina
5. transform responses
820
V1 neurons have RFs that can be:
simple RFs (simple cells) or complex RFs (complex cells), for which stimulus orientation matters.
821
RFs in cells in the input layer of V1 are similar to retinal or LGN RFs but cells in other V1 layers have:
more complex RFs.
822
What is there is a clear separation between in In SIMPLE cells?
the excitatory and inhibitory parts of the RF.
823
What are the three steps of visual processing?
retina; thalamus; cortex
824
in a cell with a simple RF, the best stimulus would be a:
bar of light – at a particular bar orientation which aligns with the excitatory strip of the simple RF.
825
In SIMPLE cells, at orientations other than the particular orientation that aligns with the excitatory strip, you will evoke:
excitation and inhibition, which will tend to cancel each other out.
826
In COMPLEX cells, there is no clear separation between what?
excitation & inhibition in the RF
827
What is very important in COMPLEX cells?
stimulus orientation
828
In COMPLEX cells, you can evoke responses from ___ the cell’s ___ (with ___ between different parts of the RF) provided you have the stimulus at the ___.
1. anywhere within
2. RF
3. graded differences
4. right orientation
829
Beyond the ___, for the more complex RFs of Simple cells and Complex cells, a critical property is the ___, unlike the case at the ___.
1. input layers of V1
2. orientation of the stimulus
3. retina or LGN
830
Overall in V1, cells code every possible stimulus orientation, why?
because for every single orientation , there is a cell which responds to that orientation – each V1 cells responds to a particular orientation, and every possible orientation of a bar of light is preferred by some V1 cell.
831
The fact that cells in V1 are selective for orientation means what?
that cells across V1 code stimulus orientation.
832
What does selective for orientation mean?
each cell responding best at one or a small range of orientations
833
V1 cells are ___, not ___ per se as at the retina and LGN (though contrast is an important property for ___).
1. “edge detectors”
2. contrast detectors
3. V1 cells
834
Selectivity for orientation allows us to distinguish things like:
letters, shapes and so on
835
In what percent of V1 cells, do you need the stimulus to be in a particular orientation AND moving in a particular direction?
about 20%
836
In COMPLEX RFs V1 cells have:
orientation AND direction selectivity.
| Therefore one particular direction and one particular orientation results in the most APs in the neuron for each cell.
837
V1 neurons show novel properties not seen at the ___.
LGN or the retina.
838
V1 neurons do not respond to the ___ the amount of light at one small spot of space versus the ___ (the centre-surround RF at the retina and the LGN) but respond to ___– they are "___". Additionally, some V1 cells are detectors of ___.
1. contrast between
2. amount of light in the surrounding region
3. a bar of light at a particular orientation
4. edge detectors
5. motion
839
The properties of V1 neurons being able to detect motion and edges are not seen at the retina or in LGN neurons and so are described as:
emergent properties of V1 (a property that emerges at V1 from the way in which these neurons process the input they receive which does not have this property.)
840
What is the idea of emergent properties?
that different levels of the brain can process information in such a way that the neurons at that level display a selectivity for something or the other (orientation, or motion) which was not simply present in the input.
841
what are the two broad streams of information flow from the retina to the brain?
A putative "Where?"& "where to?" information stream:
1. Detecting motion
2. Detecting flickering (changing) stimuli
A putative “What?” information stream
1. Fine form/detail vision (pattern, shape, texture)
2. Colour vision
842
P cells are ___ sensitive and have ___ RFs, which is good for fine detail / ___.
1. wavelength
2. small
3. acuity
843
M cells are not ___ sensitive and have ___ RFs (which are not good for fine detail / ___).
1. wavelength
2. large
3. acuity
844
M cells form which information stream?
The putative "Where?" and "where to?" information stream
845
P cells form which information stream?
the putative “What?” information stream.
846
The different ___ in LGN keep ___ the different ___ streams from the eye.
1. layers
2. separate
3. information
847
the Parvocellular layers in the LGN only get:
P (P- cell) "What?" inputs from the retina
848
the Magnocellular layers in the LGN only get:
M (M cell) ("Where/Where to?") inputs from the retina.
849
In V1, as in ___, the two ___ from the eye, the "What?" ___ stream and the "___" M stream, are ___.
1. LGN
2. streams of information
3. P
4. Where/Where to?
5. not mixed up
850
From V1, visual information flows to a number of ___, such as V2 (secondary visual cortex), V3, V4, V5, V6...
In doing so, there is some mixing between the two streams but also a ___ between the two information streams.
This results in a segregation of
___ and, potentially at least, in a segregation of function in the higher order ___.
Thus some higher-order cortical fields may specialize for the perception of form and ___, and other higher-order cortical fields specialize for the perception of ___.
1. higher-order visual areas
2. strong degree of separation
3. neural response characteristics
4. visual cortical areas
5. colour
6. movement
851
What information is in P cell inputs ("what") inputs?
colour and form
852
What information is in M cell inputs ("where/where to") inputs?
motion, and detecting changing stimuli
853
If there is ___ of visual information into ___ and these are processed in different areas of ___, we might expect that damage to different higher-order visual cortical fields can result in deficits in the perception of movement but not the ___, or deficits in the perception of form and colour but not the ___.
1. segregation
2. two streams of information
3. visual cortex
4. perception of form and colour
5. perception of movement
854
What is visual agnosia?
it is an impairment in recognition of visually presented objects
855
what is prospagnosia?
a neurological condition characterized by the inability to recognize the faces of familiar people.
856
What is movement Agnosia
The condition of motion agnosia affects an individuals ability to judge whether an object is moving."
857
What are the 3 stages of memory?
Sensory memory
Working memory
Long-term memory
858
What is sensory memory?
The very first stage of memories is the immediate but fleeting sensory memory, which comes from sensory stimuli like sound and touch. Information at this stage only stays there for 1-3 sec
859
how can information in our sensory memories enter the working (or short-term) memory?
with attention or rehearsal
860
At what point along the pathway of the stages of memories can memories be lost?
Unattended information/memories can be lost at any point along the pathway
861
how is working-memory information stored in the much larger long-term memory
through encoding
862
How is information from the long-term memory brought to the working memory?
Through retrieval
863
The brain goes through different stages in the ___. Each of these is mediated by a ___.
1. formation of memories
| 2. different neuronal network
864
What does the working memory do?
holds information in our minds for a short time in an active conscious state.
865
information generally only stays in the working memory for up to how long?
From the working memory, what happens to this information?
up to 30 seconds
| it is either lost or gets transferred into long-term memory.
866
What does the central executive system control
the flow of information in the brain
867
what are the 3 memory stores that the central executive is supported by?
The phonological loop
The visual sketchpad
The episodic buffer
868
What is the phonological loop?
A temporary storage system that translates visual words and numbers into auditory information. It is this that allows you to say things to yourself.
869
What is the visual sketchpad?
The memory store that deals with visual and spatial information, and holds images of objects in your mind's eye.
870
What is the episodic buffer?
A "back-up" store that links the working memory with the long-term memory.
871
Where is much of the working memory concentrated?
in the frontal and parietal lobes.
872
The phonological loop is generally located where? what does it do there?
on the left frontal and parietal lobes, where it interacts with neuronal networks involved with speech, planning and decision-making.
873
Where is the visual sketchpad located?
in the right hemisphere.
874
how many items can we remember in our working memory?
7(±2)
875
What happens as the amount of information increases?
Remembering the information accurately becomes more difficult
876
What is the Long-term memory (LTM)?
an enormous store of a huge set of different types of information.
877
Where does anything that has been in your memory for over 30 seconds go to if attended to?
The Long Term Memory (LTM)
878
For information to enter our long term memory, it must enter through our ___ and down pathways that process it further.
long the way, the brain determines certain ___ like ___ and whether the object is ___ or not.
1. sensory systems
2. properties
3. shape, colour, object identity
4. familiar
879
What are the 3 pathways LTM is encoded in?
Procedural Long Term Memory
Semantic Long Term Memory
Episodic Long Term Memory
880
What is Procedural Long Term Memory?
This is where you store knowledge about how to perform certain skills.
881
What is Semantic Long Term Memory
A vast storehouse of factual knowledge. Everything we have ever learned about the world may be found here. The semantic memory store is huge, so the brain sorts all of the facts into categories. This makes it easier for us to retrieve them.
882
Episodic Long Term Memory
This is where particular events and experiences you've encountered throughout your life are stored.
883
What is conditioning? What does it involve?
When skills are learned through deliberate and repeated practice. Conditioning is involved in learning skills and emotional learning.
884
What is conditioning? What is it responsible for?
When skills are learned through deliberate and repeated practice. It is responsible for learning skills and emotional learning.
885
What areas of the brain are used for conditioning?
For skill learning, the basal ganglia and cerebellum
| For emotional learning relies, the amygdala.
886
What areas of the brain are used for conditioning?
For skill learning, the basal ganglia and cerebellum
| For emotional learning relies, the amygdala.
887
What areas of the brain are used for conditioning?
For skill learning, the basal ganglia and cerebellum
| For emotional learning relies, the amygdala.
888
In memory, what are the cerebellum and basal ganglia involved in?
learnings skills and procedural memory
889
In memory, what is the amygdala involved in?
emotional learning
890
Working memory (WM) is a ___ function, ranging from sensory to parietal to premotor cortex, the medial temporal lobe, prefrontal cortex, and even including subcortical areas like the ___.
Interestingly, very ___ all activate these areas very broadly, showing that the properties of WM involve ___.
However, it's likely these different areas are not activated in the same way - ___ may be activated to represent the simple sensory elements of the stimulus, while ___ may represent an abstract concept associated with that specific sensory stimulus.
1. widely distributed
2. basal ganglia
3. different stimuli
4. neural activity across many brain areas.
5. sensory areas
6. prefrontal cortex
891
The coordination and control functions of WM, which are the domain of the ___, appear to be located in the ___ which then interfaces WM processes with ___ processes.
1. Central Executive controller and coordinator
2. prefrontal cortex (PFC)
3. Long-Term Memory
892
Brain imaging studies show that specific PFC sub-areas monitor the information from ___ and coordinate this with ___ from ___.
1. LTM
2. WM information
3. multiple brain regions.
893
Similar to WM, long-term memory is made up of a number of different components and correspondingly involves:
a number of brain areas.
894
Each component of LTM is not ___ into one specific brain area but is most likely dispersed across a large number of ____ - combinations of brain structures and the ___ running ___ them and to other areas.
The different networks do carry out different jobs.
1. "localized" (segregated)
2. different brain "networks"
3. nerve fibre tracts
4. between
895
there is evidence that recall of the names of ___ not only activates ___ involved in complex shape ___ but also ___ areas for naming things.
1. visual objects
2. high-order visual areas
3. recognition
4. auditory and language
896
The ventral visual cortical pathway consists of areas that specialize in ___ and is critically involved in allowing us to recognise ___. These areas are also active when we ___ visual objects from memory.
1. recognising object details
2. familiar objects and face
3. recall
897
What is the Declarative LTM?
the conscious, intentional recollection of factual information, previous experiences, and concepts.
898
What are the 2 categories of the declarative LTM? What do they store?
episodic memory, which stores specific personal experiences
| semantic memory, which stores factual information.
899
What does information stored in the declarative LTM allow?
it allowed us to connect to our past and allows us to plan for the future.
900
Who was Henry Molaison?
a famous patient who had damage in childhood to the brain region (the Medial Temporal Lobe) which encodes the Declarative form of LTM.
901
Declarative memories are encoded by neurons in a suite of structures that are located where?
the Medial Temporal Lobe
902
The particular regions of the Medial Temporal Lobe involved in Declarative LTM are what?
the hippocampus, entorhinal the cortex and perirhinal cortex.
However Declarative LTM is not stored in these regions.
903
In declarative LTM, what do the Medial Temporal Lobe neurons do?
encode the memory for consolidation and storage.
serve a critical role in the initial processing and storage of these memories. That information is then consolidated and stored in the temporal cortex as well as in other widely-distributed networks in the cortex.
904
Without the medial temporal lobe, like Mr Molaison, we cannot do what?
learn new events, facts and concepts.
905
what are the steps in Biological mechanisms for memory?
Action Potentials increase activated by stimulus that causes learning in pre-synaptic neuron
leads to an increase in Calcium ions in the terminal of that neuron;
activation of the enzyme that produced cAMP;
activation of the protein PKA;
number of pre-synaptic changes;
a large increase in the availability of neurotransmitters and the release of neurotransmitters.
906
Studies in simpler systems (like eye-blink reflexes in rabbits with a puff of air; the protective gill-withdrawal reflexes in sea slugs; smell conditioning in the fruit fly) show that short-term changes in these learning behaviors result from:
___, i.e., changes in the efficiency with which Action Potentials in the pre-synaptic neuron were able to elicit responses in the ___.
these short-term changes in the strength of synapses, in turn, were associated with changes in the release of neurotransmitters from the pre-synaptic neurons.
these short-term changes in the release of neurotransmitters from the pre-synaptic neurons appear to be due to the pre-synaptic terminal being over-active and allowing an accumulation of Calcium ions in the terminal, triggering processes dependent on a molecule called ___. In essence, cAMP activates a protein called ___. If the stimulus occurs only once or briefly (as is the case for most short-term learning paradigms), PKA activates substrates in the ___, such as potassium channels and proteins involved in the release (exocytosis) of ___. This will lead to a large increase in the availability of neurotransmitters and the release of neurotransmitters.
1. the short-term changes in the strength of particular synaptic connections
2. post-synaptic (target) neuron
3. cyclic AMP
4. PKA (Protein Kinase A)
5. synaptic terminals
6. neurotransmitters
907
What are the biological mechanisms that allow the longer duration storage? What do they do?
changes in synaptic efficiency - long term potentiation (LTP) or long-term depression (LTD). They maintain LTMs by more stable and permanent changes in neural connections.
908
What is Long Term Potentiation (LTP) initially due to?
the more efficient transfer at synapses using the same mechanisms as we described above for short-term memory.
909
What is LTP stabilized by?
changes in the target (post-synaptic) neurons;
activation of genes;
protein synthesis including those that cause the growth of the synapse;
increase in the neuron's responsiveness to stimulation.
910
the switch of short-term memory to long-term memory requires what?
the synthesis of new protein, particularly in the post-synaptic (target) neuron.
911
What is one of the most common and versatile signal pathways in eukaryotic cells?
the cyclic AMP/protein kinase A (cAMP/PKA) pathway.
(For example, it functions in the immune system to regulate the activation of a particular type of immune cell, the T cell system.)
912
Why are we more likely to forget declarative memory than procedural learning?
procedural learning is highly specific which protects it from interference.
In contrast, a lot of declarative memory is generalizable - especially semantic memory and so is more prone to interference.
Although, episodic declarative LTM, which is autobiographical memory, can be robust.
913
What are the reasons why we can forget?
1. decay
2. interference
3. motivated forgetting or repression
4. Retrieval Cue Failure or Absentmindedness
5. Cue-Dependent Memory Failure
6. Organic/biological problems
914
How does decay cause forgetfulness?
essentially, the memory trace fades over time. Rehearsal, or mentally going over a memory, can slow this process. This process of decay begins almost immediately if the information is not used.
915
How does interference cause forgetfulness?
one piece of information impairs the recollection of another.
Retroactive interference: new learning/information interferes with old, sometimes so much that the original memory is forgotten. The ability to recall previously learned information is greatly reduced if that information is not utilized, and there is substantial new information being presented.
Proactive interference: old learning/information interferes with the ability to make new memories. This often occurs when memories are learned in similar contexts, or regarding similar things.
916
What are the two types of interference that can cause forgetfulness?
Retroactive interference
| Proactive interference
917
How does Motivated forgetting or Repression cause forgetfulness?
it is considered to be an active process undertaken when the information is psychologically painful.
918
How does Retrieval Cue Failure or Absentmindedness cause forgetfulness?
This is where you can't recall how you stored or filed the information.
919
How does Cue-Dependent Memory Failure cause forgetfulness?
This is when we are, at the recall phase, not in the same psychological or physical state when you first learned the material.
This is especially when the learning has an emotional overlay that is absent at the time of recall -
920
How does Organic/biological problems cause forgetfulness?
caused by depression, malnutrition, Alzheimer's disease can interfere with or damage the memory storage areas of the brain preventing you from being able to access content with fidelity. Amnesia, the inability to recall certain memories, often results from damage to any of a number of regions in the temporal lobe and hippocampus.
921
What is amnesia?
the inability to recall certain memories
922
What ways are there to improve remembering?
1. Rehearsal -Maintenance - rote repetition
2. Elaborative- associate the new information with previously learned information
3. Deep processing - make the information personally relevant
4. Distributed practice- (small quantities over time) - vs. - massed practice
5. Mnemonics- Use strategies for organizing information so it can be remembered
6. Effective reading
923
What is the master clock?
An intrinsic rhythm that could be entrained to external factors.
924
What is the master clock?
An intrinsic rhythm that can be entrained to external factors like daylight.
925
All body clocks are synchronized by a master clock, called what?
the suprachiasmatic nucleus (SCN), in the brain.
926
The SCN is a nucleus located where in the Central Nervous System?
in the hypothalamus
927
Cells in the SCN have ___ because they have ___ that set a near-24-hour ___ of activity.
1. their own intrinsic rhythm
2. "clock genes"
3. rhythm
928
The SCN sends out signals to set ___ for all the separate body clocks - it ___ all the individual clocks to ___
1. the cycle of peak activity and rest
2. synchronizes
3. the master clock's rhythm.
929
The SCN sends signals to an ___ in ___, so the SCN also determines ___.
1, Arousal System of neurons
2. the brainstem and forebrain
3. arousal and alertness
930
the master clock rhythm can be ___ (synchronized/aligned) by light so that its ___ is aligned to the light/dark cycle of the ___.
1. entrained
2. 24-hour timing
3. Earth's day/night cycle
931
our arousal is at a peak ___ and our ___ is timed to occur later in the day and night.
1. during the day
| 2. sleepiness
932
The SCN is said to set a;
circadian rhythm
933
What are the 2 main elements of the Circadian rhythm?
the SCN which sends out alerting signals to synchronize body clocks
the pineal gland that releases melatonin to determine the timing of sleep.
934
The body's built-in ___ is coordinated with the day-night / ___ over a 24-hour period and ___, feeding patterns, core body temperature, ___ activity, cell regeneration, ___ production, and other biological activities.
It is the main mechanism that controls the timing of sleep, and is independent of the amount of preceding Even a ___ sleep can be ineffective or inefficient if it occurs at the "wrong" time of the ___, e.g., the time of peak arousal rather than the time of low alertness.
1. circadian clock
2. light-dark cycle
3. regulates sleep pattern
4. brain wave
5. hormone
6. sleep or wakefulness.
7. long
8. circadian cycle
935
The circadian clock is ___ of the amount of preceding sleep or wakefulness
independent
936
A circadian rhythm is an approximately 24 hour cycle in the ___ processes of ___ living beings
1. internal body
| 2. all
937
Circadian rhythms are ___ by a clock in our brains that has some ___ in it's ___
1. "endogenously generated"
2. rhythmicity
3. outputs
938
What does the rhythmicity of our circadian rhythm control?
what we do or what happens in our bodies; thereby they regulate our internal processes and our levels of alertness - hence they control many aspects of our behavior and our physiology.
939
What do things that our circadian clock controls include?
Sleep, physical activity, alertness, hormone production and levels, body temperature, immune function, cell regeneration, brain wave activity and digestive activity.
940
Each activity regulated by the circadian clock is controlled by a
___ which exhibits its own near-___ rhythms and controls ___.
1. local clock
2. 24-hour
3. circadian phenomena locally in the tissue
941
What are the "slave oscillators" synchronized by?
the master clock / SCN, which gets input from the eyes and coordinates these rhythms across the entire body to the light-dark cycle.
942
The circadian biological master clock causes highs and lows of sleepiness and wakefulness through the day. Typically, most adults feel sleepiest between: ___
2-4 a.m., and 1-3 p.m.
943
Circadian rhythms are remarkably stable across people and vary only slightly - ___ hours in humans, with a mean of ___, just slightly more than the ___.
1. between 23.5 and 24.5
2. around 24.2 hours
3. Earth's rotation
944
About ___ of people have a circadian period slightly less than the 24-hour day, and ___ have a circadian period ___.
1. 25%
2. 75%
3. slightly more than 24 hours
945
The exact intrinsic value of an individuals circadian rhythm likely depends on what? What information supports this argument?
the structure of genes responsible for circadian rhythmicity.
A strong genetic component in circadian rhythms is shown in very closely-related people, like twins, who show highly similar genetics and sleep patterns.
946
there can be ___ in the synchronization between the body clock and the ___.
1. individual differences
| 2. light-dark cycle
947
What are the two colloquial chronotypes of body clocks?
Early birds
| Night owls
948
The genes involved in creating circadian rhythms are many and show a ___. Similar ___ appear to be involved in ___. Although homologous, it is believed they ___.
1. complex interplay.
2. homologs
3. fruit flies.
4. evolved independently.
949
In mammas=ls what certain genes have been specifically identified as being involved in the sleep process?
PER 1, 2 and 3, CLOCK, BMAL, CRY1 and 2, among others.
950
What other cyclic patterns of our behavior or our physiology are there besides the circadian rhythm?
Ultradian rhythms
| Infradian rhythms
951
What are Ultradian rhythms?
a recurrent period or cycle repeated throughout a 24-hour day, an example of which is the basic Rest-Activity Cycle. Thus ultradian rhythms have periods shorter than the period of a circadian rhythm.
952
What are Infradian rhythms?
A rhythm with a period longer than the period of a circadian rhythm, i.e. with a frequency less than one cycle in 28 hours, such as menstruation, breeding, tidal or seasonal rhythms. A special type of infradian rhythm is a Circannual rhythm (annual cycles)
953
The brain's master clock is a pair of small structures called what?
the suprachiasmatic nuclei (SCN).
954
The SCN are found where?
within the hypothalamus, and are just above the optic chiasm at the bottom of the brain.
955
SCN master clock controls the timing of the what?
sleep-wake cycle
956
the SCN master clock promotes what?
arousal, Rapid Eye Movement (REM) sleep, and sleep consolidation.
957
This clock has an inherent cycle of how long?
24 hrs +/- 11 minutes.
958
Each SCN contains a small number of neurons (___), so that about ___ set the overall rhythm of our bodies.
1. about 10,000
| 2. 20,000 neurons
959
each SCN is actually divided functionally into what two parts?
the dorsomedial SCN
| the ventrolateral SCN
960
One part of the SCN; the dorsomedial SCN, contains what?
neurons that have an intrinsic rhythm of 24 hrs +/- 11 minutes that can persist under constant darkness,
961
One part of the SCN; the ventrolateral SCN, contains what?
neurons that receive direct retinal input and have the ability for light-induced gene expression to entrain (synchronize) them to the light-dark 24-hour cycle of nature.
962
The SCN has it's own___ of about 24 hours and SCN cells follow this ___.
This near-24-hour rhythm is then used to ___ the rhythms in our ___ across the entire body.
1. rhythmicity
2. near-24-hour rhythm.
3. coordinate
4. behaviours and in our physiological processes
963
```
This near-24-hour rhythm is then used to coordinate the rhythms in our behaviours and in our physiological processes across the entire body.
Thus:
Lesions of the SCN ___.
Activity in the SCN ___.
The isolated SCN ___.
The transplanted SCN ___.
```
1. abolish free-running rhythms
2. correlates with circadian rhythms
3. continues to cycle
4. imparts rhythm of the donor to the recipient
964
SCN neurons produce ___ in a near-24-hour ___.
1. APs
| 2. rhythm
965
The maximum rate of APs of SCN neurons occurs when?
at mid-day
966
the rate of APs falls again when?
At night
967
Change in the rate of APs in SCN neurons occurs ___, indicating that the ___ in SCN cells must have a rhythmicity in ___.
1. intrinsically
2. sub-cellular processes
3. their actions
968
The AP firing rate in SCN cells is modulated by factors that we know also control ___. Two such factors, are ___ and ___.
1. our alertness and arousal state.
2. light shone into the eye
3. the hormone melatonin produced by the brain's pineal gland
969
What type of light activates the firing rate of SCN cells the most?
blue wavelength light
970
The AP ___ in many SCN neurons is modulated by ___ in the eye, which causes a ___, especially if it's ___.
1. firing rate
2. light
3. sustained burst of APs
4. short-wavelength light.
971
Applying melatonin directly on to the SCN or ___ causes a ___ of the SCN neurons. This is likely due to the presence of ___ through which melatonin acts to control ___ through the SCN.
1. in the immediate vicinity of the SCN
2. decrease in the AP firing rate
3. decrease in the AP firing rate
4. rhythms
972
Although circadian rhythms are endogenous, they are also adjusted (entrained) to ___ by ___.
1. the local environment
| 2. external cues called zeitgebers
973
what does endogenous mean?
built-in or self-sustained
974
what does zeitgeber mean in German?
time giver
975
What do zeitgebers include?
external stimuli like sunlight and temperature (high in the day time, low at night) among others
976
An internal zeitgeber of the SCN is ___, which is an ___ that ___ various ___ in the body.
1. the hormone melatonin
2. "endogenous synchronizer"
3. stabilizes and reinforces
4. circadian rhythms
977
Zeitgebers do what?
"entrain" (synchronize) the circadian clock to a different cycle.
978
Entrainment occurs when:
rhythmic or arhythmic physiological or behavioral events match their period to that of an environmental oscillation.
979
Sunlight helps ___ your clock to the ___. Without it you'd have to depend on other cues (___) to entrain it (eg: temperature)
1. synchronize (entrain)
2. day-night cycle of the Earth
3. zeitgebers
980
What is the most powerful zeitgeber on the SCN?
light coming into the eye
981
SCN neurons release the ___ neurotransmitters: ___ and ___.
| These neurotransmitters activate the ___ and cause changes in the expression of ___ in these SCN cells.
1. excitatory
2. Glutamate
3. PACAP
4. SCN
5. clock genes
982
what does PACAP stand for?
pituitary adenylate cyclase-activating polypeptide
983
Light entrains (synchronizes) the intrinsic oscillations in the SCN through what?
a special set of retinal ganglion cells (RGCs) that contain a special light-absorbing pigment called melanopsin.
984
A special set of intrinsically-___ RGCs (___) are photoreceptor cells that send their ___ (i.e., they communicate information) directly to the ___ via a nerve pathway called the ___.
1. photosensitive
2. ipRGCs
3. axons
4. SCN
5. retino-hypothalamic tract
985
The ipRGCs are particularly sensitive to the absorption of ___ - which is why you're advised not to use ___ before going to bed.
1. short-wavelength (high frequency) "blue" light
| 2. computers or other devices emitting short-wavelength light
986
What are the steps of the affect of light exposure on the SCN?
Light exposure (input); ipRGCs (melanopsin); retino-hypothalamic tract; SCN; output (sleep-wake cycle: arousal, REM, timing, consolidation)
987
What other zeitgebers act on the SCN besides light in the eye?
When you eat: you can speed up or delay your internal clock. If you shift your breakfasts, lunches, and dinners to later in the day, this may also move your body's internal clock back, making a later bedtime feel more natural.
The timing of exercise: can also influence the clock - if you switch to routinely going to the gym in the evening instead of the morning, that too will shift your circadian rhythm to going to sleep later.
988
What other zeitgebers act on the SCN besides light in the eye and melatonin?
When you eat: you can speed up or delay your internal clock. If you shift your breakfasts, lunches, and dinners to later in the day, this may also move your body's internal clock back, making a later bedtime feel more natural.
The timing of exercise: can also influence the clock - if you switch to routinely going to the gym in the evening instead of the morning, that too will shift your circadian rhythm to going to sleep later.
989
The pineal gland contributes to the circadian rhythm and the sleep-wave cycle through:
the production and release of the hormone, melatonin, which can shift the phase of oscillations in the SCN .
990
In humans and most diurnal mammals, the secretion of melatonin shows which features linking it to the sleep wave cycle?
Sleep is the least likely to occur in the time before secretion.
Secretion occurs at night with a robust circadian rhythm.
Start of secretion, and a subsequent increase in sleep propensity, occurs about 2 hours before the person's regular bedtime.
Maximum levels in our blood occur between 3 - 4 am.
Duration of melatonin synthesis and release increases with the length of the night suggesting that the amount of time for which melatonin is elevated is the most important signal conveying the photoperiodic message.
991
Sleep is ___ in the time before melatonin secretion
the least likely to occur
992
What secretes melatonin?
the pineal gland
993
Melatonin secretion occurs at night with a ___.
robust circadian rhythm.
994
During the start of melatonin secretion, a subsequent ___ occurs about ____ the person's regular bedtime.
1. increase in sleep propensity
| 2. 2 hours before
995
Maximum melatonin levels in our blood occur between ___.
3 - 4 am.
996
Duration of melatonin synthesis and release ___, suggesting that the amount of time for which melatonin is elevated is the most important signal conveying the ___.
1. increases with the length of the night
| 2. photoperiodic message
997
The circadian (rhythmic) release of melatonin is regulated by what?
the suprachiasmatic nucleus (SCN) of the hypothalamus.
998
The SCN ___ the release of the hormone ___, produced by the pineal gland, until ___ decrease in the evening/night.
1. inhibits and therefore delays
2. melatonin
3. light levels
999
The daily variation in melatonin levels is remarkably consistent across:
people, and within the one person across weeks
1000
Melatonin levels start to rise only after dark (i.e., when light levels decrease), at about ___ and increase until about ___. They then decline again to low levels by ___.
1. 9 pm
2. 2-3 am
3. 7-8 am
1001
Melatonin entrains and shifts the circadian rhythm in a ___, i.e., causing an adjustment in timing (a "phase" adjustment) to ___ the circadian clock. Thus, taking melatonin during ___ will delay evening sleepiness by shifting the phase of ___ whereas melatonin given in the evening can advance ___.
1. "chronobiotic" function
2. entrain or re-entrain
3. the morning
4. circadian rhythm
5. both of these phases
1002
Melatonin promotes sleep ___ in a ___ by increasing the ___ to sleep
1. onset and continuity
2. "hypnotic" function
3. homeostatic drive
1003
Melatonin promotes sleep ___ in a ___ by increasing the ___ to sleep
1. onset and continuity
2. "hypnotic" function
3. homeostatic drive
1004
The chronobiotic function and hypnotic function of melatonin appear to be:
equal
1005
The receptors through which melatonin acts to entrain or re-entrain the ___ and ___, have their highest density in ___ but are also found ___. Therefore, unsurprisingly, melatonin can have a number of effects in the body other than in ___.
1. body clock
2. to cause sleepiness
3. the SCN
4. widely throughout the brain and other organs
5. regulating the sleep-wake cycle
1006
Different melatonin receptors appear to be responsible for ___ and for ___.
1. the onset of sleep
| 2. the phase shifting effects
1007
The function of melatonin is mainly to ___ rather than induce sleep per se - that is, it does not necessarily ___ but it can ___ sleep to permit a good night's rest.
1. mediate information about dark (night)
2. induce sleep
3. promote
1008
In diurnal animals darkness ensues, what happens in the SCN and melatonin release?
there is a decrease in light activation to the SCN, melatonin levels increase.
1009
what are diurnal animals?
animals active during daytime
1010
What are nocturnal animals?
animals active during nightime
1011
In nocturnal animals, melatonin is primarily secreted by ___ during ___ - but clearly doesn't lead to sleep ___. Instead, in nocturnal animals, the ___ coincides with ___, confirming that it is not, in itself, responsible for sleep.
1. the pineal gland
2. darkness
3. to sleep
4. onset of melatonin secretion
5. locomotor activity
1012
Melatonin is best seen as:
an "endogenous synchronizer" that stabilizes and reinforces various circadian rhythms in the body, with its main effects on sleep via the circadian rhythm of sleep-wake regulation.
1013
Nerve fibers from the SCN run to where? then where after that?
the paraventricular nuclei in the brain's hypothalamus, then down to the spinal cord.
1014
Via the ANS's sympathetic division, light information runs out of the spinal cord to where? and then back to where?
the superior cervical ganglia (SCG), and then back into the brain and to the pineal gland.
1015
the SCN inhibiting the pineal gland results in what?
the reduction of the production of melatonin.
1016
melatonin production is inhibited by what?
light
1017
what activates SCN neurons?
light
1018
why is melatonin production stimulated by darkness?
because when there is little light, the SCN activation from ipRGCs decreases and hence SCN inhibition of the pineal gland also decreases, therefore melatonin production decreases.
1019
Both melatonin and light information via the neural information from ipRGCs can ___ act on ___. Thus, light input and the circadian system work together to ___ of the sleep-wake cycle.
1. directly
2. the sleep-wake system.
3. modulate properties
1020
Light exposure is much more potent in its phase-shifting effects than ___. This can also vary depending on the exact time the melatonin is given and ___ occurs, in relation to the ___ of the patient.
1. melatonin
2. light exposure
3. circadian rhythm
1021
Melatonin has the opposite effect on the SCN to what?
light exposure
1022
Given that light, through the SCN, can suppress ___,, prior to the invention of ___, the duration of melatonin secretion must have varied with ___ , with the night time duration of melatonin secretion being expanded in ___ and was ___.
1. melatonin production and secretion
2. electric lighting
3. the seasons
4. winter
5. compressed in summer
1023
The time of the circadian period of sleep/wake can vary from:
23.8 to 27.1 hours
1024
The daily sleep-wake cycle is influenced by a ___, where an internal clock" drives the rhythm of the sleep-wake cycle and a ___ that determines the recent amount of ___.
1. circadian process
2. homeostatic "sleep propensity"
3. sleep and wakefulness accumulated.
1025
Maximum sleepiness occurs when:
Core Body Temperature (CBT) is at its lowest and melatonin levels are at their highest.
1026
Circadian systems need to be considered in relation to what three differing levels of organization of information and operation?
1. the way in which the physical environment communicates (or 'Inputs') key information
2. the 'Intrinsic' brain factors, consisting of the master clock and its linked regulatory systems
3. the way in which the circadian system coordinates all other hormonal, metabolic, immune, thermoregulatory, autonomic nervous and other physiological processes to optimize the relationships between behavior and body functions (that is, the 'Outputs')."
1027
the 'Intrinsic' brain factors, consisting of ___ (notably secretion of melatonin from ___). These contribute to ___
1. the master clock and its linked regulatory systems
2. the pineal gland
3. sleep onset, sleep architecture, sleep-wake cycles and other central nervous system (CNS)-dependent behavioral changes.
1028
What is a circadian rhythm disorder?
a persistent or recurrent pattern of sleep disturbance
primarily caused by alterations in the circadian timekeeping system or a misalignment between the endogenous circadian rhythm and exogenous factors that affect the timing or duration of sleep.
1029
what does exogenous mean?
growing or originating from outside an organism.
1030
Why may timed melatonin administration be a more viable way to change the circadian rhythm in clinical practice when needed?
Because patients demonstrate more compliance in taking melatonin at the right time than in pursuing the necessary exposure to light.
1031
Light information affects the ___, via an indirect pathway that originates from the __ and goes via the ___ and eventually to the pineal gland.
1. Pineal gland
2. ipRGCs
3. SCN
1032
What is the main function of the hormone melatonin?
To mediate information about dark / night.
1033
What is homeostasis?
the dynamic state of balance (equilibrium or steady state) of our internal physical and chemical conditions.
1034
Sleep has a regulatory system enabling organisms to ___ for the ___ or ___.
1. compensate
2. loss of sleep (e.g. due to sleep deprivation)
3. surplus sleep (e.g by prolonging sleep in the morning or by napping).
1035
What system "reminds" the body when it needs to sleep, maintaining the overall balance between sleep and wakefulness.
The sleep-wake homeostasis system
1036
What is sleep?
a state of unconsciousness that has to be actively initiated by the brain
1037
Adequate sleep, like adequate nutrition and physical activity, is vital to ___ Research suggests that adults need ___ to be well rested.
1. our well-being.
| 2. at least 7-8 hours of sleep each night
1038
When healthy adults are given unlimited opportunity to sleep, they sleep on average between:
8 and 8.5 hours a night.
1039
But ___ from person to person. Some people appear to need only about 7 hours to avoid ___, whereas others need 9 or more hours of sleep.
1. sleep needs vary
| 2. problem sleepiness
1040
how much sleep do each of these age groups need?
```
newborns (0-3 months age)
infants (4-11 months)
toddlers (1-2 years)
preschoolers (3-5 years),
school-aged children (6-13 years)
teenagers (14-17 years)
Young adults (18-25 years) / Adults (26-64 years)
Older adults (65+)
```
newborns (0-3 months age): 14 - 17 hours,
infants (4-11 months): 12 - 15 hours,
toddlers (1-2 years): 11 - 14 hours,
preschoolers (3-5 years): 10 - 13 hours,
school-aged children (6-13 years): 9 - 11 hours,
teenagers (14-17 years): 8 - 10 hours ,
Young adults (18-25 years) / Adults (26-64 years): 7 - 9 hours.
Older adults (65+): 7 - 8 hours.
1041
recent surveys show the average adult now sleeps ___.
More than ___ of adults report daytime sleepiness so severe that it interferes with work, driving, and social functioning at least a few days each month.
Evidence also shows that children's and adolescents' sleep is ___. Lack of sleep may have a direct effect on ___.
1. fewer than 7 hours a night.
2. one-third
3. shorter than recommended
4. children's health, behavior, and development.
1042
if you have ___, sleeping in on a weekend does not completely erase your ___.
1. lost too much sleep
| 2. sleep debt
1043
Some evidence shows that short naps (___) can make up, at least partially, for the ___ and improve ___.
But naps don't ___ a good night's sleep. One study found that ___ to the pattern seen with adequate nighttime sleep.
If a nap lasts longer than ___, you may have a hard time waking up fully.
In addition, late afternoon naps can make falling asleep at night ___.
1. up to an hour
2. sleep missed on the previous night
3. alertness, mood, and work performance.
4. substitute for
5. a daytime nap after a lack of sleep at night did not fully restore levels of blood sugar
6. 20 minutes
7. more difficult
1044
Sleep depends on what two processes?
a Sleep homeostasis drive or Sleep pressure system riding on top of a rhythm variation during the day-
the Circadian clock - in our arousal levels.
1045
Sleep ensues when the sleep ___ rises to a high level and ___ starts to decline, a "___" is opened, letting sleep flood in
1. pressure
2. arousal
3. sleep gate
1046
The body's built-in circadian clock is the main mechanism that:
controls the timing of sleep through a chemical called melatonin.
1047
The circadian clock controls the ___.
Instead this clock is coordinated with the ___ and regulates ___.
Even a long sleep can be ___ if it occurs at the "wrong" time of the circadian cycle, e.g., ___.
1. timing of sleep independently of the amount of preceding sleep or wakefulness.
2. day-night / light-dark cycle over a 24-hour period
3. sleep patterns, feeding patterns, core body temperature, brain wave activity, cell regeneration, hormone production, and other biological activities
4. ineffective or inefficient
5. the time of peak arousal rather than the time of low alertness.
1048
the circadian rhythms alone are not sufficient to ___. Therefore, there is also a ___, which is balanced against ___.
1. cause and regulate sleep
2. sleep-wake homeostasis factor
3. the circadian element.
1049
Sleep-wake homeostasis is an internal biochemical system that depends on:
sleep chemicals building up in the body - using a chemical called Adenosine - it generates a homeostatic sleep drive or pressure to sleep and regulates sleep intensity.
1050
What does Adenosine do?
it generates a homeostatic sleep drive or pressure to sleep and regulates sleep intensity.
1051
Sleep-wake homeostasis is not ___ on the day/light cycle but on the ___
The longer we have been awake, the stronger becomes the ___, and the greater the likelihood of falling asleep;
Conversely, ___, the more the pressure to sleep ___, and the more the ___.
1. directly dependent
2. amount of time since you last slept.
3. desire and need to sleep
4. the longer we have been asleep
5. dissipates
6. likelihood of awakening increases
1052
As you stay awake through the day ___.
However, the ___ released from the pineal gland is what ___.
1. Adenosine accumulates and makes you sleepier and sleepier the longer you've been awake.
2. melatonin
3. finally gives the brain permission to sleep by alerting it that it is time to sleep.
1053
Given that there are ___: the two separate ___, with different but ___ brain systems, determine the ___ that we all undergo.
1. two systems responsible for sleep
2. biological processes
3. partially overlapping
4. sleep-wake cycle
1054
The circadian rhythm system (also called the circadian clock), set by our master clock, the SCN, regulates:
the timing of periods of sleepiness and wakefulness throughout the day and produces an "alerting" signal to enhance wakefulness, and to actively counteract the accumulation of homeostatic drive for sleep.
1055
The restorative sleep-wake homeostasis system, signals a need for sleep, regulating:
sleep intensity, and it helps us maintain enough sleep throughout the night to make up for the hours of being awake.
1056
What do the two sleep systems do?
The homeostatic system regulates sleep intensity
| the circadian clock regulates the timing of sleep.
1057
The circadian system sets the ___ and the homeostasis system ___.
The ___ of the two systems is seen in the fact that ___ has major effects on the ___, but has only minor effects or no effect on ___.
1. timing of wake/sleep
2. independently sets the intensity or depth of sleep
3. independence
4. sleep deprivation
5. homeostatic regulation of sleep
6. the circadian pacemaker
1058
the homeostatic system is principally dependent or regulated by what? What happens to this the longer you stay awake?
a chemical called adenosine which builds up the longer you are awake
1059
The circadian clock is principally dependent on what? when is this inhibited and produced?
melatonin, which is shut off indirectly by light in the eyes during daytime but is released from this inhibition at night and then produced in greater amounts (hence melatonin has been some times referred to as the "hormone of darkness").
1060
Sleep depends on what 2 systems?
Sleep homeostasis drive
| Sleep pressure system
1061
The sleep "pressure" appears to originate, at least in part, from ___.
the brain's periodic need to replenish low stores of energy:
1062
During wakefulness, ___ , the body's principal ___ is used up.
1. glycogen
| 2. store of energy
1063
As glycogen is broken down into ___, ___ begin to accumulate in the brain.
as ___ are depleted throughout the day, extra-cellular adenosine builds up over the course of the day.
Then, during sleep, the adenosine is removed and replaced by ___.
1. adenosine
2. extracellular levels of adenosine
3. the brain's glycogen energy stores
4. new glycogen
1064
During wakefulness, ___ gradually increase in areas of the brain that are important for ___, especially the ___.
With higher and higher ___, adenosine ___.
Then, adenosine levels decrease during ___.
1. adenosine levels
2. promoting arousal
3. reticular activating system in the brainstem and the basal forebrain
4. concentrations
5. inhibits arousal and causes sleepiness
6. sleep
1065
Evidence for the sleep-regulating role of adenosine is shown by the facts that:
high levels of adenosine lead to ___.
blocking adenosine's actions in the brain ___,
injections of adenosine or similar compounds induce ___,
adenosine concentrations in the brain shoot up dramatically in animals forced to ___
Common stimulants like caffeine in coffee, tea, cola and energy drinks, and theophylline in tea and chocolate, are ___, inhibiting or dampening its ___, and thereby ___.
1. sleepiness
2. increases alertness
3. apparently normal sleep
4. stay awake
5. adenosine antagonists or receptor blockers
6. sleepiness effect
7. maintaining alertness
1066
Adenosine operates as a ___ in the brain, and has the effect of ___, particularly those involving the neurotransmitters ___.
1. neuromodulator
2. inhibiting many of the bodily processes associated with wakefulness
3. noradrenaline, acetylcholine and serotonin
1067
Adenosine also may inhibit the ___ and, at the same time, remove ___ from the ___, triggering them into ___.
1. basal forebrain arousal system
2. inhibition
3. sleep-promoting VLPO neurons
4. activity
1068
What acts as a homeostatic regulator of the sleep need.
adenosine
1069
The main sleep-wake homeostatic mechanism is ___, and particularly ___ sleep.
That is, ___ is a pressure to enter into ___.
This pressure is only ___ by actually getting that deep non-REM sleep.
1. non-REM sleep
2. deep or slow-wave
3. the pressure to sleep
4. deep non-REM sleep.
5. relieved
1070
The loss of REM sleep also leads to an increase in ___ , , this loss appears to be ___, and with certain differences between ___.
1. the tendency to enter REM sleep
2. compensated up to a certain extent only
3. different animals
1071
What is REM also known as?
rebound sleep
1072
In the sleep that follows ___, NREM sleep takes precedence over ___ and we spend more time in ___ than in REM sleep. This suggests that ___.
1. acute sleep deprivation
2. REM sleep
3. NREM sleep
4. the homeostatic mechanisms for the two sleep states differ.
1073
During the day:
Homeostatic sleep drive ___, effectively making a person more and more sleepy as the day goes on.
However this is countered and moderated by ___ , at least until ___.
1. typically increases
2. the circadian drive for arousal
3. late evening
1074
Late evening:
The circadian clock slackens off its ___ and begins ___ instead.
This opens the "___" when ___ is at its greatest distance above ___.
Recent theories theorizes that individual groups of neurons in the brain enter into a state of sleep after a ___, and that, once enough ___ are in this sleep state, the whole organism ___.
1. alerting system
2. sleep-inducing melatonin production
3. sleep gate
4. the homeostatic sleep drive
5. the circadian drive for arousal
6. certain threshold of activity has been reached
7. groups of neurons
8. falls asleep
1075
During the night, while sleep is actually being experienced:
the homeostatic sleep drive ___,
___ continues.
1. rapidly dissipates
| 2. circadian-regulated melatonin production
1076
In the early morning:
melatonin secretion ___ and the circadian alerting system ___ again.
Eventually, ___ begins to overcome the ___, triggering ___.
1. stops
2. begins to increase its activity
3. the circadian drive for arousal
4. homeostatic sleep drive
5. awakening
1077
In the morning after awakening:
the SCN is being entrained by the ___ of the morning. It is going to activate the ___ and that will gradually increase your ___.
At the same time, the active SCN ___. Light, via the ___ through the SCN, is also able to ___ in the pineal gland.
Since you've just woken up from sleep, your glycogen levels are ___ and your adenosine levels are ___.
1. increasing light
2. Ascending Arousal System (AAS)
3. arousal / alertness levels
4. suppresses the pineal gland from producing melatonin
5. indirect pathway
6. suppress melatonin production
7. high
8. low
1078
During the day:
the SCN and the AAS ___ and you ___. (There is the dip in arousal and concomitant drowsiness from ___.)
Through this period, you're using up ___ to do things and building up ___ which means you're building up a ___.
1. dominate
2. remain alert.
3. 1-3 pm
4. glycogen
5. adenosine
6. sleep debt
1079
As the light level declines in the late evening and into the night:
___ of the SCN starts to ___. This reduces the ___, which is then capable of ___.
___ builds up in the brain from the early evening and into the ___ of your sleep period, and then its release stops in ___. This doesn't support a view of melatonin as being responsible for sleep, since it's low when you're in deep sleep. Instead it supports the view that it triggers ___.
As the melatonin builds up, it shifts ___ and Adenosine has built up enough to the point of ___
As you sleep, Adenosine levels ___ and glycogen starts to be ___.
1. light entrainment
2. decline
3. SCN suppression of the pineal
4. producing and releasing melatonin
5. Melatonin
6. first 2 hours
7. the middle of the night
8. the onset of sleep
9. the circadian rhythm towards sleep
10. initiating sleep and determining its depth and duration.
11. slowly decline
12. produced and stored
1080
What does glycogen break down into?
adenosine
1081
What type of chemical is adenosine?
a neuromodulator
1082
what is sleep broadly segregated into?
REM and non-REM sleep
1083
What does REM stand for?
rapid eye movement
1084
What can we differentiate the different components of sleep with?
the EEG, the electroencephalogram, that displays brain activity.
1085
What are the three stages of NREM sleep?
```
Stage 1 (N1)
Stage 2 (N2)
Stage 3 (N3)
```
1086
What are the characteristics of Stage 1 NREM sleep?
Light sleep, easily awakened easily by noises or other disturbances
· Eyes move slowly, muscles relax, and heart and breathing rates begin to slow.
1087
What are the characteristics of Stage 2 NREM sleep?
Defined by slower brain waves with occasional bursts of rapid waves.
1088
What are the characteristics of Stage 3 NREM sleep?
Brain waves become even slower
· Higher-voltage slow delta waves account for more than 20% of the sleep brain activity as measures in the EEG.
· Difficult to awaken from this stage.
1089
In stage 3 NREM sleep, higher-voltage slow delta waves account for hoc much of the sleep brain activity as measures in the EEG?
20%
1090
How much of the night do you spend in stage 2 NREM sleep?
Over half of the night
1091
What are the characteristic of REM sleep?
Your eyes move rapidly in different directions, even though your eyelids stay closed.
· Your breathing becomes more rapid, irregular, and shallow.
· Your heart rate and blood pressure increase and fluctuate irregularly.
· Your arm and leg muscles are temporarily paralyzed so that you cannot "act out" any dreams you may be having.
· REM period length and density of eye movements increases throughout the sleep cycle
1092
What are the 2 components of REM sleep
tonic component
| phasic component
1093
The phasic component is a ___ characterized by ___.
1. sympathetically driven state
| 2. rapid eye movements, muscle twitches, and respiratory variability
1094
The tonic REM component is a ___ with no ___.
1. parasympathetically driven state
| 2. eye movements
1095
In a typical ___, you cycle through the stages of ___ into ___, then progressively out towards the___ sleep stage and then into ___, and back again to deep sleep.
1. sleep period
2. NREM sleep
3. deep sleep
4. light N1
5. REM sleep
1096
Sleep starts as you transition from the ___ usually into ___, typically the lighter stages ___, and then gradually into deep sleep (___).
At least in the first phase of the night's sleep, NREM sleep lasts ___, getting progressively ___ from stage 1 NREM through stage 2 to stage 3 NREM sleep.
From deep (N3 NREM) sleep, you then progressively cycle back out into ___ and then into ___. You typically first enter REM sleep about ___ after falling asleep (transitioning from wakefulness into N1 NREM sleep).
This cycling occurs a ___ a night.
1. waking stage
2. light non-REM (NREM) sleep
3. N1 and N2
4. N3 NREM sleep
5. 70- 100 minutes
6. deeper
7. stage N2 and then stage N1
8. REM sleep
9. 1-1.5 hours
10. few times
1097
From wakefulness, how long does it usually take to fall into REM sleep?
1-1.5 hours
1098
in the first phase of the night's sleep, NREM sleep lasts how long?
70-100 minutes
1099
How much of a nights sleep consists of each stage of sleep?
about ___ of your sleep time is spent in the lightest stage, Stage N1,
___ of your sleep time is spent in the next deeper stage N2,
about ___ is spent in the deep sleep stage N3
and the rest (about ___ of your sleep time) is spent in the REM stage of sleep.
1. 5%
2. half
3. 20%
4. 25%
1100
The first REM period of the night may be less than ___ in duration and you cycle back then into ___. After that, the sleep stages ___ while you sleep.
The NREM-REM cycles vary in length from ___ initially to ___ later in the night.
REM sleep occurs ___ during a normal 8-hour sleep period.
As you sleep, REM sleep time becomes ___: the last one may be up to ___ long.
In contrast, time spent in ___ sleep becomes ___ throughout the night.
1. 10 minutes
2. NREM sleep
3. repeat themselves continuously
4. 70-100 minutes
5. 90-120 minutes
6. 4-5 times
7. longer
8. 60 minutes
9. stage 3 NREM
10. shorter
1101
Typically, N3 sleep is present more in the ___ of the night, whereas REM sleep predominates in the ___ of the night.
By the time you wake up, nearly all your later sleep time has been spent in ___.
This can be helpful clinically as ___ (disruptive sleep disorders) such as ___ typically occur in the first third of the night with the presence of ___.
This contrasts with ___, which typically occurs in the ___ of the night.
1. first third
2. last third
3. stages 1 and 2 of non-REM sleep and in REM sleep.
4. NREM parasomnias
5. sleepwalking
6. N3 sleep
7. REM sleep behavior disorders (RBD)
8. last half
1102
In slow wave sleep:
Muscles ___, and movement becomes scarcer. Breathing becomes more ___, and sympathetic activity and heart rate ___.
___ decreases and oxygen consumption declines by about ___.
We become progressively ___, and less likely to ___ or to be awakened by external stimuli.
Hormone secretion ___, and most ___ are secreted during SSW.
The ___ of SSW with hormone release and brain and body inactivity suggests a ___.
1. progressively relax
2. even and slow
3. decline
4. Brain activity
5. 40%
6. less responsive to external stimuli
7. awaken spontaneously
8. increases
9. growth hormone and sexual maturation hormones
10. anabolic character
11. rest and restorative function
1103
During REM, as you've seen, the EEG becomes ___, resembling the activity of an ___.
Sympathetic activity ___, ___ increase and become irregular.
Most of the muscles of the body are ___ via ___.
The eye muscles are not paralyzed, and are ___, generating ___.
We are most cut-off from ___ and least arousable by ___ during REM sleep.
We are more likely to ___ during REM sleep than the deeper stages of SSW.
1. desynchronized
2. awake brain
3. dominates
4. heart rate and respiration
5. actively inhibited or paralyzed (atonia)
6. brainstem projections to the motor neurons.
7. phasically active
8. rapid eye movements
9. sensory input
10. external stimulation
11. awaken spontaneously
1104
The discovery of the electroencephalogram (EEG), the method of ___, has helped identify that there are a number of ___, differentiated by type of ___, that differentiates ___ from wakefulness through sleep.
1. recording brain waves
2. very distinct brain stages
3, brain activity
4. alertness stages
1105
wakefulness is defined by what type of EEG pattern?
a small-sized (low voltage) but fast EEG pattern, called desynchronized or activated EEG.
1106
The high frequency EEG activity consists primarily of ___ (___) and ___ (___). The EMG recording also show ___ during wakefulness.
1. frequencies in the beta range
2. 14 to 30 Hz
3. gamma range
4. 30 to 50 Hz
5. high activity
1107
sleep is characterized by ___ and ___, a pattern called ___. This can be seen to occur systematically through ___ which is actually differentiated into three stages, labelled Stages 1-3, and varying ___ through the night.
1. higher voltages
2. slower waves
3. synchronized EEG
4. NREM sleep
5. systematically in depth of sleep
1108
Sleep Stages 3 and 4 were so similar that they are now merged into a:
single deep sleep stage: stage 3 NREM sleep.
1109
In humans, the stages of ___ depend on the extent of the slowing down of the ___ from the ___ in the ___ to move to the___: ___.
1. NREM sleep
2. EEG
3. low-voltage (small-sized) fast-frequency brain waves
4. wakefulness stage
5. large amplitude slowest-frequency brain waves
6. the delta frequency (0.5 to 4 Hz) range
1110
What are spindles on an EEG?
waxing and waning bursts of frequencies in the sigma (12 to 14 Hz) band.
1111
Which sleep stage is notable for the presence of spindles.
Stage 2 NREM
1112
As we noted previously, Stages 3 and 4 of NREM sleep, with brain activity at the ___ and consisting of ___, are further grouped under the term ___.
During this state, the ___ can show ___ and there is low or minimal muscle activity (___) across the body's muscles.
In animal studies, the terms SWS and NREM sleep are often used ___ as the state is rarely sub-divided in terms of the , i.e., in terms of exactly what frequency of slow waves are present.
1. slowest delta-wave frequency (0.5 to 4 Hz)
2. large amplitude activity
3. slow wave sleep (SWS)
4. electro-oculogram (EOG; electrical activity recorded from near the eye)
5. gradual rolling eye movements
6. EMG
7. synonymously
8. slowing down of the EEG
1113
Slow wave sleep is interrupted by periods of ___ (REM, i.e., ___) sleep, when, despite all the overt signs of continuing sleep, the ___ is remarkably different.
In fact, the EEG in humans during REM sleep is essentially identical to that recorded during ___.
1. rapid eye movement
2. active or paradoxical
3. activity of the brain
4. wakefulness
1114
the EOG reveals what?
rapid bursts of eye movements,
1115
In rodents, the EEG is typically dominated by frequencies in ___ during REM sleep and ___ appears as ___ as well as eye movements.
Importantly, and in all species, the ___ shows the complete ___ that is a characteristic of ___.
1. the theta band
2. phasic activity
3. twitching of the vibrissae
4. EMG
5. loss of muscle tone (i.e., atonia)
6. REM sleep
1116
Dreaming can occur during any sleep state, but is most frequent during what stage?
REM sleep
1117
The dreams of REM sleep tend to be more ___ than those of ___.
1. vivid and active
| 2. Slow Wave Sleep (SWS)
1118
Highly oppressive dreams, nightmares and sleepwalking occur during which sleep stage?
stage 3 Slow Wave Sleep.
1119
Loss of muscle tone is a characteristic of which stage of sleep?
REM sleep
1120
A number of brain areas show patterns of ___ in ___ during the different stages of sleep.
1. decreases or increases
| 2. activity
1121
Sleep essentially depends on an interplay between two major sets of brain pathways:
A set of ___ that send pathways running up the brain to ___, called the ___.___, has neurons that promote sleep by ___.
Note that the POA generates ___, but a different set of nuclei, in ___, generates ___.
1. brainstem structures
2. the cortex
3. ascending arousal system (AAS)
5. in the hypothalamic Preoptic area (POA)
6. inhibiting the AAS arousal/wakefulness areas
7. NREM sleep
8. the pons
9. REM sleep
1122
POA ___ contain ___and ___.
Both chemicals are ___.
High levels of activity in ___ will ___ activity in neurons that ___ from them.
The POA sleep neurons sends output to ___ and so ___ arousal at the same time as it ___.
1. sleep neurons
2. GABA (γ-aminobutyric acid)
3. galanin, a neuropeptide that acts through three G protein-coupled receptors (GPCRs or metabotropic receptors).
4. inhibitory neurotransmitters
5. POA neurons
6. inhibit
7. receive input
8. structures of the AAS
9. block
10. promotes NREM sleep
1123
POA sleep neurons themselves are blocked by ___ that ___, specifically ___
The various ___ that contain these chemicals will ___ POA sleep neurons.
1. AAS neurotransmitters
2. promote being awake
3. Acteylcholine (ACh), Noradrenaline (NA) and Serotonin
4. wake-active AAS neurons
5. inhibit
1124
____ is called the "happy chemical" because of its popular image as a contributor to feelings of well-being and happiness, though its actual biological function is ___.
1. Serotonin
2. complex and multifaceted
3. modulating cognition, reward, learning, memory, and numerous physiological processes
1125
The ___ between POA sleep system and the AAS wakefulness structures causes rapid "flip-flop" switching between the two ___.
So, sleep is caused by ___, and wakefulness is caused by ___.
___ activates the POA sleep system neurons, so as ___ starts to accumulate, ___ become more active to ___ the AAS system.
___ can act on the POA neurons to ___ and to help suppress ___.
1. mutual inhibitory activity
2. states of wake and NREM sleep
3. increased activity in POA sleep system neurons
4. increased activity in AAS neurons
5. Adenosine
6. sleep debt
7. POA sleep neurons
8. inhibit
9. Melatonin
10. enhance their activity
11. AAS neurons
1126
NREM sleep is caused by the increased activity in what? , and wakefulness is caused by increased activity in AAS neurons.
POA neurons
1127
As the POA sleep system becomes more active, it will:
block the AAS neurons and block wakefulness.
1128
wakefulness is caused by increased activity in what?
AAS neurons.
1129
As AAS structures become more active, they will:
block POA neurons and block NREM sleep.
1130
___ is caused by increased activity in AAS (___) neurons and ___ is caused by increased activity in POA (___) neurons.
1. Wakefulness
2. Ascending Arousal System
3. NREM sleep
4. Preoptic Area
1131
During day:
The SCN has it's ___, due to the various clock genes, and this is entrained (___) to the ___ via the ___.
The output of the SCN is ___ to the pineal gland, preventing the production and release of ___ which would dictate the ___.
This output is excitatory to ___.
These structures are inhibitory to ___. This inhibition reduces the ___ to the Ascending Arousal System (AAS) which is, therefore, able to send arousal signals to the ___.
At the same time, the SCN output is ___.
1. internal rhythmicity
2. synchronized
3. day/night light/dark cycle by light
4. retinohypothalamic tract
5. directly inhibitory
6. melatonin
7. timing of sleep
8. particular hypothalamic nuclei
9. Preoptic Area (POA)
10. inhibition from the POA
11. thalamus and cortex
12. excitatory to the AAS
1132
At night:
The SCN's ___ is moving to a ___ through the clock genes and as the light entrainment of the SCN is also ___.
The inhibitory output of the SCN to ___ decreases, allowing the ___ which would dictate the ___.
Melatonin is ___ to the SCN, reducing its inhibition of ___.
The inhibition from these structures to ___ is reduced.
This reduced inhibition to the POA from the SCN, together with the influence of ___, allows the POA to inhibit the ___ and prevent it from sending arousal signals to ___.
This starts the process of ___.
1. internal rhythmicity
2. downturn
3. declining as it's becoming darker, with night
4. the pineal gland
5. production and release of melatonin
6. timing of sleep
7. inhibitory
8. the hypothalamic nuclei.
9. the Preoptic Area (POA)
10. Adenosine at the POA
11. Ascending Arousal System
11. the thalamus and cortex
12. sleep cycling
1133
The AAS wake system and the POA sleep system:
mutually inhibit each other.
1134
Touch and pain are part of what?
the somatosensory system.
1135
What does the somatosensory system do?
provides information from the body (from the skin and from deep structures such as the viscera, muscles, tendons and joints) about touch, pressure, vibration, pain, temperature and proprioception (i.e., body position
1136
What is discriminative information?
information we can locate and identify and whose fine features we can distinguish and discriminate very well
(such as fine touch, pressure, vibration, position information, movement information)
1137
What is non-discriminative information?
information we cannot locate and identify and whose fine features we cannot distinguish and discriminate very well
(such as pain and temperature, and a crude, affective form of touch)
1138
What is the fine information that we use from mechanoreceptors in the skin (cutaneous mechanoreceptors) to identify objects?
discriminative somatic information
1139
what is information that can lead to the sensations of pain that we use from receptors in the skin (cutaneous nociceptors)?
non-discriminative somatic information
1140
what do you call something in the skin
cutaneous
1141
What is nociception/nocir-reception
noxious (damaging or potentially damaging) stimuli (NOXIOUS sensitivity)
1142
What does the somatosensory system provide information about?
exteroception:
mechanoreception
thermoreception
nociception
proprioception
Interoception
1143
what dimensions is fine mechanoreception along?
touch-pressure / flutter-vibration
1144
The somatic senses are detected by receptors that are what?
the endings of nerve fibres.
1145
in the somatosensory system, the receptors are not ___ but the ___.
1. specialised cells
| 2. specialised endings (the terminals) of nerve fibres
1146
The nerve endings are specialised for specific stimuli through what?
special ion channels and accessory structures.
1147
the specialised endings (the terminals) of nerve fibres that are the somatosensory receptive zones must be specialised for what?
the type of stimulus they detect
1148
The ion channels of the ___ of the ___ makes the nerve fibres ___.
Different terminals have different ___ that respond to different types of stimuli, allowing the different ___ to be signalled.
This is how our skin can provide information about the ___ of what we touch, and also about whether an object is hot or cold, or whether something is painful.
1. receptive zone
2. terminals
3. specialised for detecting one stimulus type
4. specialised ion channels
5. somatic sensations
6. fine details
1149
Another way, besides specialised ion channels, in which the nerve endings specialise is through:
the accessory structure associated with the endings.
1150
Another way, besides specialised ion channels, in which the nerve endings specialise is through:
the accessory structure associated with the nerve endings.
1151
What are accessory structures formed by?
connective tissue and fluid.
1152
What are nerve endings with no accessory structures called?
free nerving endings
1153
What are free nerve ending specialised for detecting?
pain and temperature
1154
Why do free nerve endings in pain and temperature not need accessory structures?
because the skin, due to its properties of being viscous and elastic, modifies the way in which stimulus energy arrives at the somatic receptor.
1155
Both types of accessory structures modify the way in which ___.
This can modify the ___, allowing it to become ___ for particular aspects of a stimulus
2. stimulus energy reaches the terminal
3. sensitivity of the receptor (the terminal)
4. specialised
1156
The biological response to the physical energy of the stimulus is what?
a change in electrical charge.
1157
What are the 2 ways sensory receptors can be activated?
Mechanical displacement of some part of the cell membrane by the stimulus.
The stimulus activating molecules that then act on the cell membrane.
1158
How are mechanoreceptors and some nociceptors activated?
by mechanical displacement of some part of the cell membrane by the stimulus.
1159
How are thermoreceptors, and most nociceptors activated?
The stimulus activating molecules act on the cell membrane.
1160
When a receptor is activated, what is the resultant effect?
the opening of ion channels to allow a net influx of positive charge into the nerve terminal. This depolarizes the membrane, producing a change from the resting state - i.e., a change in the RMP
1161
How can somatic nerve fibres be classified?
by their axon diameters and the presence/absence of myelin.
1162
what do axon diameters and the presence/absence of myelin affect in a neuron?
the neurons conduction velocity (the speed at which action potentials are transmitted along their length)
1163
The fastest conducting nerve fibres are those transmitting information related to the ___, allowing us to monitor second-by-second, if the the terrain is even or uneven and in turn if any ___ need to be made.
1. nerve fibres
2. position of body in space (proprioception)
3. adjustments
1164
What are the slowest conducting nerve fibre classes?
the A-delta and C classes
1165
The slowest conducting nerve fibres, the A-delta and C classes, are those carrying what type of information?
pain and temperature information.
1166
Why are nerve fibres carrying pain and temperature information the slowest conducting nerve fibres, the A-delta and C classes?
Because changes in these stimuli, or the occurrence of events causing these sensations, especially of pain, do not frequently occur. Hence, the body doesn't need to expend energy creating a myelin sheath or increasing the axon diameter to produce a larger neuron.
1167
how are somatosensory nerve endings specialised for specific stimuli.
Special ion channels and accessory structures.
1168
Touch sensations are:
cutaneous discriminative mechanoreception.
1169
what is the information coming from the ski that we can discriminate and localise well?
touch, pressure, flutter, vibration.
1170
What are the major mechanoreceptors that contribute to discriminative mechanoreception in humans are called? Where are they found?
Meissner’s corpuscles (upper layers of skin)
Merkel’s disks (upper layers of skin), and
Pacinian corpuscles (deep in the skin).
1171
In hairy skin, ___ replace Meissner’s corpuscles. These are ___ wrapped around ___ and activated by ___.
1. hair follicle receptors
2. nerve endings
3. the base of the hair follicle
4. bending of the hair follicle.
1172
Accessory sheaths modify how the energy from one stimulus acts on what?
the nerve terminal underneath.
1173
In mechanoreceptors, ion channels will open if you apply what?
stretch, pressure, or displacement to the membrane in which such channels are embedded.
1174
In mechanoreceptors:
When the ion channels open, they allow an ___ of ___. Compared to the ___, the nerve terminal is ___.
This will make the RMP more___ than the resting state - i.e., the ___ will have changed from the resting state to a more ___.
1. influx (in flow)
2. Na+ and Ca++ ions
3. resting state
4. gaining positive charge
5. positive
6. membrane potential
7. depolarized direction.
1175
What is the point of having so many different touch receptors?
to be able to signal to the brain different aspects of what we touch.
1176
Each afferent fibre receives input from ___.
These ___ are all of the ___. All of these receptors are mechanoreceptors sensitive to ___, and they all send information to ___ via ___ of nerve fibre.
1. only one type of mechanoreceptor
2. nerve fibres
3. A-β class of sensory afferent nerve fibres
4. mechanical indentation of the skin
5. the brain
6. the same type
1177
Touch receptors are differentiated in terms of information provided because the different receptors vary in which two properties?
adaptation rate
| receptive field size.
1178
What is adaption rate?
Adaption rate determines the ability to tell if a stimulus is changing and how fast it is doing so.
1179
What is receptive field size?
Receptive field size determines how precisely you can identify where the stimulus is happening on your skin - or the fine details of what you touch.
1180
What are the 3 major dimensions of fine touch?
form perception
texture perception
vibration perception
1181
What is form perception?
What is its most important physiological property?
What cutaneous receptors are most involved?
the ability to identify the form and shape of objects solely by touch (as in Braille reading);
Fine details (small receptive fields)
Merkel's disks
1182
What is texture perception?
What is its most important physiological property?
What cutaneous receptors are most involved?
the ability to feel and discriminate the smoothness/roughness of an object
Fine details (small receptive fields) and sensitivity to low-relatively low spacing (low frequencies)
Merkel's disks (mainly) and Meissner's corpuscle (lesser)
1183
What is vibration perception?
What is its most important physiological property?
What cutaneous receptors are most involved?
the ability to distinguish between something fluttering on our skin (associated with perception of frequencies 40Hz) through to something vibrating on our skin surface (frequencies from 40−400Hz)
Low frequency sensitivity + high frequency sensitivity
Meissner's corpuscle + Pacinian corpuscles
1184
where is our touch sensibility best?
at our fingertips and our tongue and lips.
1185
Our ability to use touch information (___) is not constant across the skin but ___ across the body, correlating with the properties of the ___ responsible for these different sensations.
1. our touch sensibilities
2. varies
3. cutaneous mechanoreceptors
1186
we can link the variation in tactile perception to the way we use these ___.
eg:
Our fingertips are used to explore the world, and in keeping with that, we have ___ at our finger tips.
1. body parts
| 2. fine acuity and vibration sensitivity
1187
* Define the receptor properties adaption rate and receptor field size:
Adaption rate determines the ability to tell us if a stimulus is changing and how fast it is doing so.
Receptive field size determines how precisely you can identify where the stimulus is happening on your skin, or in the fine details of what you touch.
1188
* State the 3 major dimensions of fine touch and then describe each of them.
The 3 major dimensions of fine touch are form perception, texture perception, and vibration perception.
Form perception is the ability to identify the form and the shape of objects solely by touch, and involves Merkel's disks.
Texture perception is the ability to feel and discriminate the smoothness/roughness of an object, and involves mainly Merkel's disks and to a lesser extent Meissner's corpuscles.
Vibration perception is the ability to distinguish between something fluttering on our skin through something vibrating on our skin surface, and involves both Meissner's corpuscles and Pacinian corpuscles.
1189
Pain is a major type of:
non-discriminative somatic information
1190
Pain can came from both:
skin (cutaneous) structures and deep (visceral) structures
1191
Why is pain a critical sensation?
because it alerts us to things in the environment that can harm our bodies.
1192
What is a reason to study pain?
pain is among the most debilitating conditions and affects a surprising large number of people in their daily lives.
Pain often persists, and often recurs. It can be crippling.
1193
The 3 components of pain that the experience of pain depends on are:
(a) Sensory coding of stimuli.
(b) Motivational/affective component (whether your brain wants to attend to the input signalling potentially damaging stimuli) or is engaged in other things.
(c) Cognitive/cultural component (whether your brain has learnt not to bother with that type of input signalling potentially damaging stimuli).
1194
What are the steps of pain processing?
Potentially damaging input; spinal cord processing; cognitive systems + sensory processing + motivational/affective systems; motor responses
1195
Pain sensations depend on the ___ AND ___. This means that sensory processing of pain input in the brain can be significantly ___ by other ___.
1. peripheral input
2. whether the brain wants to attend to it yet
3. modulated
4. brain systems
1196
When people are in moments of high stress, they may not notice:
a potentially damaging input.
1197
Nociceptors are the receptors responsible for:
pain sensations.
1198
Pain sensations (___) originate from the ___, not from special receptor cells.
1. nociception
| 2. specialised endings of nerve fibres
1199
Noxious stimuli are transduced into electrical activity where?
at the peripheral free nerve ending terminals of the A-δ and C classes of sensory nerve fibres.
1200
What type of nerve fibres signal fine touch sensations?
Aβ nerve fibres
1201
The C fibres are ___ and Aδ fibers are ___. Because axon size and myelination ___, the C fibres are the ___.
It's likely because pain isn't (or shouldn't be) ___ as long as you learn from your experience of what is ___.
So since making axon diameters larger and getting them myelinated are both ___ on the body, there was no ___ to making the pain nerve fibres large and myelinated for ___.
1. unmyelinated nerve fibers
2. thinly myelinated
3. speeds up the transmission of AP along the length of the nerve fibre
4. slowest conducting nerve fibres
5. a common experience
6. noxious
7. energetically demanding
8. evolutionary advantage
9. rarely-occurring events
1202
Nociceptors are the most ___ of the somatic receptors, and are present in ___ than touch-sensitive receptors (___) and thermoreceptors (___).
1. abundant
2. higher density
3. 9x more
4. 15x more
1203
What are the 4 basic classification of nociceptors? What are each of them sensitive to?
Nociceptors sensitive to temperature (different ones for Hot and Cold pain)
Nociceptors sensitive to mechanical stimuli
Nociceptors sensitive to mechanical and thermal stimuli, and
Polymodal Nociceptors sensitive to thermal, mechanical and chemical stimuli (also known as Wide dynamic range nociceptors)
1204
Nociceptors respond to the same stimuli as other ___ BUT only at stimulus levels outside the ___, and at levels that will harm the organism (___). Then there is a ___ with the __ of the damaging stimulus.
1. cutaneous receptors
2. normal range
3. injurious levels
4. systematic increase in responses
5. increase
1205
Different ion channels ___ the effects of different ___.
Specific ___ are sensitive to heat, mechanical stimuli, protons (H+ as in acids) and cold..
In all these cases, it is the ___ that excites the ___.
```
1. transduce
2, noxious agents
3. receptors or ion channels
4. net entry of positive charge (generally Na+)
5. nociceptor afferents
```
1206
One of the most commonly involved ion channels in ___, and one of the best understood, is the ___ (also involved in normal temperature sensations ), which is part of a ___.
1. pain
2. TRPV1 ion channel
3. TRP superfamily of ion channels
1207
The TRPV1 channel allows ___ to move, leading to nerve cell ___ and eventual ___.
TRPV1 is activated at ___.
another TRPV channel involved in pain sensations to hot temperatures is the ___ which is activated at ___.
The TRPV1 receptor can also bind the chemical ___. That may explain the ___ also evoked by eating hot chilies or wasabi.
___ leads to a painful, burning sensation of scalding heat and pain.
Opening of the TRPV1 channel leads to ___ which in turn leads to ___ and the excess Ca++ leads to many effects on cellular processes.
Many of the later effects are detrimental, like ___.
1. cations (positively-charged ions)
2. depolarization
3. 43 ∘C
4. production of APs further along the neuron
5. TRPV2
6. 52 ∘ C.
7. capsaicin (in hot chilies), allyl isothiocyanate (in mustard and wasabi) and allicin (garlic).
8. hot burning pain sensations
9. Activation of TRPV1
10. Ca++ influx
11. release of Ca++ from internal stores in the cell,
10. breakdown of cytoskeletal proteins, and the degradation of mitochondria.
1208
* Explain the TRPV1 receptor's response when eating spicy foods:
Spicy foods have specific chemicals that are responsible for our interpretation of heat. The TRPV1 receptor can bind the chemical capsaicin found in chillies, allyl isothiocyanate in mustard and wasabi and allicin found in garlic. Activation of TRPV1 leads to a painful, burning sensation of scalding heat and pain- often explaining some of our more extreme reactions to very spicy food.
1209
Pain ratings for heat parallel changes in ___.
1. firing rates of Aδ nerve fibres
1210
The responses of nociceptors match well with ___ and can very well account for ___. This is well illustrated if we compare the ___ in a nociceptor fibre when we apply a ___ to the skin and, at the same time, we ask the person to rate the sensations of pain induced by that ___.
1. human judgements about pain
2. pain sensations.
3. train of action potentials
4. damaging stimulus
5. painful stimulus
1211
Both measures of heat - ___ - increase in a very ___ manner, suggesting that our perceptions of ___ are very strongly dependent on the physiology (___).
1. the pain we feel and the number of APs being sent to the brain
2. similar
3. heat-induced pain
4. the number of APs in the nerve fibres
1212
Fast and slow pain sensations parallel the presence of what?
different conduction rates of Aδ and C pain nerve fibres.
1213
Since the two classes of nerve fibres transmit at ___, therefore their inputs would arrive at ___.
From some body parts (___), pain sensations evoked by a stimulus have two components: ___.
These two components correspond well to the two classes of ___, with ___ transmitting the initial fast pain and ___ transmitting the slower dull pain.
1. different rates
2. different times in the CNS
3. mainly the trunk and arms/hands
4. an initial fast, sharp pain followed by a slower, dull pain
5. nociceptor afferents
6. A-δ afferents
7. C fibres
1214
Skin areas with tissue injuryas show what?
Allodynia & Hyperalgesia.
1215
Skin areas with tissue injuries show what?
Allodynia & primary hyperalgesia.
1216
What is allodynia?
where non-noxious (innocuous) stimuli now are felt as painful)
1217
what is Primary hyperalgesia?
when pain stimuli cause more intense pain.
1218
in undamaged skin:
low levels of stimulus ___ do not cause ___, and are therefore rated as ___.
as stimulus intensity increases, we rate the pain as ___ with the stimuli being rated as ___.
1. intensity
2. pain sensations
3. innocuous
4. increasingly more intense
5. noxious
1219
in damaged skin:
low levels of ___, previously rated as innocuous, now are reported as ___; this is the phenomenon of ___.
As stimulus intensity increases, we now ___ rate the pain as more intense than before – this is the phenomenon of ___.
1. stimulus intensity
2. painful
3. Allodynia
4. increasingly
5. Hyperalgesia
1220
What accounts for allodynia and primary hyperalgesia?
Nociceptor sensitisation
1221
We can link the sensations of allodynia and primary hyperalgesia to what? what is this due to?
changes in the endings of the nociceptor nerve fibres from the damaged area of skin
due to chemicals released from the damaged skin acting on the endings of the nerve fibres.
1222
The ___ of the nociceptors correlates with the fact that we too become ___ applied to a region that has been previously ___.
1. sensitisation
2. more sensitive to injurious stimuli
3. injured
1223
After injury:
allodynia (where low skin temperatures that were not painful before injury and did not evoke ___, now evoke ___), and
hyperalgesia (where skin temperatures that were felt as painful before injury and did evoke ___, now evoke ___).
1. neural responses in the nociceptors
2. pain sensations and responses in the nociceptors
3. neural responses in the nociceptors
4. stronger pain sensations and more responses in the nociceptors
1224
The TRPV1 channel is involved in what?
tissue sensitisation.
1225
Damage to tissues causes the release of ___ like ___ from cells of the ___, into the damaged ___.
These can cause ___. A by-product of these effects is ___ out of the blood vessels to cause swelling in the ___.
1. inflammatory agents
2. histamine
3. inflammatory pathway and from neurons
4. tissue
5. dilation (swelling) of local blood vessels
6. fluid leakage
7. injured tissue
1226
the TRPV1 ___ is activated by the ___ caused by ___.
Tissue damage also causes release of chemicals which can ___ and thereby ___.
1. ion channel
2. stretch
3. the local fluid accumulation and swelling
4. sensitise the TRPV1 ion channel
5. modulate pain transduction
1227
* Define allodynia and hyperalgesia:
Allodynia is where non-noxious stimuli are now felt as painful. For example, if you injure your finger, even a light touch to the finger can make you yell out in pain.
Hyperalgesia is where pain stimuli cause more intense pain than normal levels. For example, the same injured finger being squeezed that would normally be rated mild, is now intensely painful.
1228
Homeo means ___, and stasis means ___. So, homeostasis is about keeping things ___.
1. similar
2. stable
3. similar or stable
1229
In biology, a living organism keeps ___ through ___.
1. their internal environment stable
| 2. homeostasis
1230
The internal environment is anything having to do with ___.
Important factors that shape the internal environment include ___.
Through ___, the body works to keep these factors the same, so that the internal environment ___.
1. the inside of the body
2. body temperature, ion concentrations, water content, and blood glucose levels (the concentration of sugar in the blood).
3. homeostasis
4. does not change
1231
homeostasis is how our body does what?
stops its internal environment from changing.
1232
we are constantly being influenced by our ___.
external environment, which is constantly changing
1233
What helps us maintain our internal body temperature?
homeostasis
1234
what is the homeostasis mechanism that acts when you are too hot?
the body sweats
1235
what is the homeostasis mechanism that acts when you are too cold?
the body shivers
1236
The body fights to keep its internal environment ___, even when the ___ is acting to change it. This process is called ___.
1. the same
2. external environment
3. homeostasis
1237
* define homeostasis, include the terms internal environment and external environment in your definition.
Homeostasis is the process by which the body maintains a stable internal environment even when our external environment is changing.
1238
homeostasis is very important for our ___.
This is because our bodies work best under ___. Our body temperature, blood pressure, water concentration and other factors need to be within ___ for us to ___. If they fall outside these ranges, we can ___.
1. health
2. certain conditions
3. certain ranges
4. function properly
5. get very sick, or even die
1239
A healthy body temperature for a human is between ___.
Any lower or higher and we can start having problems.
This is why people can die by falling into cold water. The water is ___ for the body to be able to ___, and the person's body temperature ___. This gives them a condition called ___, which can be fatal.
1. 36.5°C and 37.5°C
2. too cold
3. maintain a stable internal temperature
4. starts to drop
5. hypothermia
1240
Homeostasis is important for ___. This includes animals, plants, ___. All living organisms need to control their ___ in order to stay healthy.
1. all living organisms
2. fungi and even bacteria
3. internal environment
1241
* Summarise the importance of homeostasis in maintaining a constant internal environment:
Our bodies need our internal environment to be kept stable. Our internal environment is designed to operate best within a certain range or state. Homeostasis helps to return or adjust the internal environment back to its optimal range after deviations from an outside influence. This maintenance of a constant internal environment allows us to stay healthy and alive despite external changes.
1242
our external environment is ___.
This includes things like ___.
1. everything around you.
2. the temperature, humidity and composition of the air, the presence of chemicals and the presence of resources, like food and water.
1243
In homeostasis, the variable is what?
the part of the internal environment that the body is controlling.
1244
In homeostasis, the set point is what?
the ideal value for a variable
1245
What is the set point for internal body temperature?
37°C
1246
In homeostasis the reference range is what?
the acceptable range of values for a variable.
1247
In homeostasis, so long as the body can keep the ___ inside the ___, the organism will ___.
.
1. variable
2. reference range
3. remain healthy
1248
For example, while the ideal temperature for a human body is ___, you will be healthy as long as your body temperature is somewhere between ___.
1. 37°C
| 2. 36.5°C and 37.5°C
1249
What are the variable, set point and reference range for blood glucose levels
Variable: Blood glucose levels
Set point: 5 mmol / L
Reference range: 4-7 mmol / L
1250
In homeostasis, the body works to keep a ___ near its ___ and inside its ___.
1. homeostatic variable
2. set point
3. reference range
1251
The body could change a variable's ___ for many reasons.
Often, it is because the body is trying to manage ___. Sometimes, in order to ___, the body must ___ another.
1. set point or reference range
2. many variables at once
3. manage one variable
4. sacrifice
1252
An example of the change of a variables set point is:
During exercise, the muscles need ___ than normal. Like almost all tissues in the body, they get their oxygen from ___.
Therefore, the body can deliver more oxygen by making the ___. By pumping harder, it can better ___ around the body.
However, when the heart pumps harder, it also causes the body’s ___ to rise.
This leaves the body with a dilemma: in order to ___, it needs to ___.
Delivering oxygen is ___ than maintaining a normal blood pressure, so the body changes the ___ for blood pressure and allows it to rise.
Having high blood pressure puts strain on ___. If a person has high blood pressure for a long time, they can have an ___.
When the person stops exercising, their set point for blood pressure should ___, and the body can take measures to ___.
1. more oxygen
2. the blood
3. heart pump harder
4. circulate blood
5. blood pressure
6. deliver enough oxygen to the muscles
7. increase its blood pressure
8. more important
9. set point
10. the heart and blood vessels
11. increased risk of a heart attack
12. drop down again
13. return blood pressure to normal level`
1253
Changing the set point can:
| Therefore, it is important to:
have important consequences for homeostasis.
| return the set point to normal as soon as possible.
1254
Another reason the body might change a variable's ___, is if its ideal value is ___.
For instance, normally a good ___ is around 37°C
. However, when the body has an ___, it can be good to have ___, because this helps ___.
Therefore, when a person is sick, their body can raise the ___ for its body temperature.
1. set point and reference range
2. different under certain circumstances than normal
3. body temperature
4. infection
5. a slightly higher temperature
6. the immune system fight off the infection
7. set point
1255
what were autonomic functions formerly called?
vegetative functions.
1256
What are autonomic functions?
Any body function that is not normally under conscious or voluntary control.
1257
All neurodegenerative disorders appear to involve:
A change in the shape of a ___ within neurons to result in the production of a ___.
The rogue proteins ___ more of the ___, in a chain reaction. The rogue proteins ___ to form ___ in vulnerable ___.
The accumulation of rogue proteins “stuffs up” the function of many ___ and ___.
Release from the cells and spread of these “rogue” distorted proteins then ___.
```
1. normal protein
2, disease-specific “rogue” protein
3. recruit and convert
4. normal protein into the abnormal form
5. accumulate and stick
6. insoluble aggregates
7. neurons and glial cells
8. organelles
9. kills the cell
10. propagates the disease through the brain.
```
1258
he effects that rogue proteins have on cellular function are similar (though not identical) to the processes that occur in:
prion diseases
1259
Another common feature of Neurodegenerative diseases is damage to ___.
Neurodegenerative diseases all appear to involve problems with the mitochondria- the .
Mitochondria are called the "power houses" of the cell because they are the site where there is the ___. This molecule stores energy in the bonds between ___.
Damage to the mitochondria causes the cell to have ___, resulting in ___ later.
1. Mitochondria
2. “power house” of the cell
3. Phosphate molecules and the Adenosine molecule
4. production of the energy molecule ATP
5. less or no energy molecules to power its work
6. cell death
1260
Eukaryotic cells are characterized by what?
a membrane-bound nucleus.
1261
A major source of difficulties with having ___ is that they block the cell's mechanisms for ___.
1. rogue proteins
| 2. getting rid of unwanted or damaged proteins and peptides
1262
The two major intracellular quality control & recycling mechanisms for protein homeostasis in eukaryotes are:
a) chaperone-mediated Autophagy (CMA)
| b) the ubiquitin-proteasome system (UPS
1263
What is chaperone-mediated Autophagy (CMA?
CMA is where "chaperone" proteins guide molecules to destruction in lysosomes within cells
1264
What is the ubiquitin-proteasome system (UPS)?
The UPS is used for degradation of short-lived proteins & soluble misfolded proteins.
1265
What does Autophagy eliminate?
long-lived proteins, insoluble protein aggregates & even whole organelles (e.g., mitochondria, peroxisomes) & intracellular parasites (e.g., bacteria).
1266
Both protein clearance systems require the molecules that need to be destroyed to be ___. This is achieved by a process of ___ where a molecule called ___ is attached to a ___.
1. tagged in some way to identify them as the ones to be destroyed
2. Ubiquitylation
3. Ubiquitin
4. specific amino acid (lysine) on the target protein
1267
Degradation via UPS is initiated by ___. ___ then recognized by subunits of ___.
1. sequential addition of ubiquitin chains to target proteins
2. Polyubiquitylated proteins
3. multicatalytic protease complexes called proteasomes.
1268
Autophagy is characterized by formation of ___, which later fuse with___, forming autolysosomes degrading ___.
1. double-membrane structures (autophagosomes)
2. lysosomes
3. autophagosome contents
1269
The two main problems in neurodegenerative diseases like PD are:
Disturbances in mitochondria generate ___. ___ of reactive oxygen and nitrogen species ___, leading to ___. Oxidative modifications ___
The rogue proteins also block ___ - the UPS system and chaperone-mediated autophagy (CMA) where "chaperone" proteins ___.
1. reactive oxygen species
2. Excessive production
3. modifies proteins
4. inactivation, crosslinking, and aggregation
5. modify the lysosomal membrane and crosslink membrane proteins.
6. the cell's machinery to get rid of "dud" proteins
7. guide molecules to destruction in the structures within cells called lysosomes
1270
What are the 3 harmful factors (the "Bermuda triangle" of) in neurodegenerative diseases like PD?
Oxidative modifications
Mitochondrial dysfunction
Protein degradation
1271
Abnormal proteins:
interfere with other normal proteins within cells, preventing them from ___
can block ___ and, as Calcium is critical to trigger many ___, this blocks normal cellular functioning
can affect mitochondrial function reducing ___
can translocate to ___ & affect ___
The abnormal proteins can interfere with vesicle transport along ___.
1. functioning normally
2. Ca++ release from intracellular stores
3. cellular reactions
4. ATP availability
5. nucleus
6. DNA transcription
7. microtubules
1272
All neurodegenerative diseases commence from a ___ (e.g., ___).
1. core area deep in the brain or brain stem
| 2. substantia nigra or locus coeruleus
1273
From core deep areas, neurodegenerative diseases spread to involve ___. As they spread to involve other areas, the number of ___ exhibited by the patient increases.
Thus the appearance of more symptoms - ___ - is often a good indicator of the ___.
1. many cortical areas
2. symptoms (deficits)
3. the "recruitment" of more symptoms
4. spread of the disease for diagnostics
1274
Parkinson's Disease (PD) is what?
a progressive neurological disorder that typically becomes manifest (visible) at around fifty years of age.
1275
what is the largest known risk factor for the development of PD? Other risk factors of causing PD include what?
aging
| exposure to toxins and heredity.
1276
the benefits of what are a preventative measure for PD?
regular aerobic exercise
1277
The typical picture we have of some one with Parkinson’s disease is of a person with ___ - an almost continual ___.
However, a person with Parkinson's may also experience other ___ changes.
1. motion disorders
2. shaking (tremor)
3. physical, mental and behavioral
1278
Parkinson's occurs about how many times more in men than in women.
1.5 times more
1279
In most cases of PD, there are no ___ to definitively detect the disease, so it can be difficult to ___.
1. medical tests
| 2. diagnose accurately
1280
In fact, people often dismiss early symptoms of Parkinson's such as a ___ as the ___.
1. loss of smell
| 2. effects of normal aging
1281
People with Parkinson's typically have what four main symptoms?
1. Tremor (trembling) in hands, arms, legs, jaw, or head.
2. Stiffness of the limbs and trunk (making it difficult to initiate a movement).
3. Slowness of movement (Bradykinesia - related to the stiffness).
4. Impaired balance and coordination, sometimes leading to falls.
1282
Other symptoms of PD, excluding the 4 main symptoms, may include:
cognitive changes:- problems with thinking, depression and other emotional changes; difficulty swallowing, chewing, and speaking; urinary problems or constipation; skin problems; fatigue; and sleep disruptions.
1283
The symptoms of Parkinson's ___ over time, and ___ people.
1. develop progressively
| 2. vary between
1284
In the early stages, the symptoms of PD are ___, often on just ___ the body:
Affected people may feel ___, or have difficulty getting out of a chair.
They may notice that they ___.
They may also report sleep problems, constipation, decreased sensitivity to smell, and restless legs.
1. very subtle and occur gradually
2. one side of
3. mild tremors
4. speak too softly, their handwriting is slow, or that their faces lack expression and animation
1285
In the later stages of the disease, ___ become more obvious and affect ___ the body:
There are distinct ___ including leaning forward, small quick steps as if hurrying forward, and ___ of the arms.
At this point people with Parkinson's will usually have a slowness of movement, known as ___ -
− this also means they have trouble ___ movement and will take a lot ___ than someone without the disease.
1. motor symptoms
2. both sides of
3. gait changes
4. reduced swinging
5. bradykinesia
6. initiating or continuing
7. longer to complete tasks
1286
What is the technical term for slowness of movement?
Bradykinesia
1287
* Contrast the early stages of PD with the late stages?
The symptoms of PD develop progressively over time and vary dramatically between people. In the early stages of the disease, the symptoms are subtle and occur gradually- usually on just one side of the body. In late stages, symptoms become obvious and affect both sides of the body. In late symptoms, symptoms become obvious and affect both sides of the body, representing the neurodegenerative nature of this disease. Where people in early stages of PD have mild tremors, late stage patients have constant tremors and distinct gait changes that are indicative of serious motor difficulty, or Bradykinesia
1288
The basal ganglia is critical for what?
our fine-movement control.
1289
Parkinson's disease primarily affects the ___.
basal ganglia.
1290
The basal ganglia is a collection of ___ inside the brain.
four nuclei (clumps of neutrons)
1291
What do the basal ganglia structures mainly communicate through?
the neurotransmitter, dopamine.
1292
The basal ganglia selects which of ___ to execute at a given time and ___ one behaviour and another.
1. several possible behaviours
| 2. switching between
1293
In Parkinson's disease, there is an average range of ___
| loss of ___s in one of the nuclei in the ___, the ___.
1. 70-80%
2. dopaminergic (neurons using dopamine) neuron
3. basal ganglia
4. substantia nigra
1294
In PD, The loss of ___ causes other areas in the ___ to become ___.
Due to the overactivation of other basal ganglia nuclei, the ___, which are ___, become overactive and in turn, creates flow-on effects that ___, compromising ___.
There is a degree of tolerance so that ___
of these neurons must die before ___ occur.
;
1. dopamine
2. basal ganglia
3. abnormally overactive
4. output nuclei of the basal ganglia
5. inhibitory
6. reduce the activity of the motor cortex
7. fine motor control
8. at least 40%
9. characteristic PD symptoms
1295
People with PD also lose the neurons in a lower brain nucleus called ___. This is the main area in the brain where a chemical called ___ is made, which has a key role in our ___.
These neurons use noradrenaline as part of the Autonomic Nervous System (ANS), and specifically in the ___.
1. the locus coeruleus of the pons
2. noradrenaline
3. stress and panic responses
4. Sympathetic Nervous System part of the ANS.
1296
The loss of noradrenaline explain some of the non-movement features that are present in Parkinson's patients like:
Fatigue.
Irregular blood pressure.
Decreased movement of food through the digestive tract (this is all smooth muscle).
A sudden drop in blood pressure when a person stands up from a sitting or lying-down position.
Major cholinergic changes
1297
Cellular death in PD may involve ___, making it difficult to pre-determine and treat.
Various theories suggested causes of PD to range from ___.
1. many external factors
2. endogenous (within the body) chemical reactions, exposure to specific environmental factors and neurotoxins, to genetically determined susceptibility or predisposition.
1298
There is a form of PD which occurs from early life, which is:
familial and clearly due to genetic factors.
1299
In PD, many neurons in the substantia nigra contain ___, unusual clumps of ___. This protein is not well understood, but its abnormal form as Lewy bodies is a hallmark of PD neuropathology. ___ can be transmitted from one neuron to another and ___.
1. Lewy bodies
2. the protein alpha-synuclein
3. Alpha synuclein
4. spread throughout the brain
1300
Alpha-synuclein may play a role in the development of both ___ sporadic cases of ___.
1. (rare) familial and (more common)
| 2. Parkinson's disease
1301
In a small set of rare cases of familial (___) PD, the alpha-synuclein gene produces either ___ or ___ — and these may be ___ and result in ___.
1. hereditary
2. too much alpha-synuclein protein
3. an abnormal form of the protein
4. toxic
5. neuron dysfunction
1302
Alpha-synuclein pathology has been found in some body systems not ___, and even in patients who did not experience any symptoms of Parkinson's. Researchers have now begun to investigate the role that alpha-synuclein may play in ___.
This pathology suggests that PD can affect many areas beyond the ___, and even outside the ___ — consistent with the diversity of the clinical features of Parkinson's disease and not just the ___.
1. traditionally associated with PD
2. regulating the release of dopamine, and the production of synaptic vesicles
3. substantia nigra
4. Central Nervous System
5. typical movement disorders
1303
Alzheimer's Disease is the ___ leading cause of death in ___, killing more than ___ combined.
1. 6th
2. the United States
3. breast cancer and prostate cancer
1304
Alzheimer's Disease is the most common type of what?
dementia
1305
what is dementia?
the loss of cognitive functioning (thinking, remembering, and reasoning) and behavioural abilities.
1306
Dementia generally is a ___ - the problem worsens over time and there is ___.
1. progressive disease
| 2, no cure
1307
AD is the ___ leading cause for death for older people. ___ of the ___ people in the U.S. with AD are ___.
1. 3rd
2. 5%
3. 5 million
4. younger than 65
1308
Dementia can progress until what?
loss of cognitive function and behavioural abilities interfere with daily life and activities.
1309
Each level of dementia has different:
symptoms
1310
What are the symptoms of the mildest stage of dementia?
Short-term memory is affected, and the person finds it hard to learn and retain new information. The disease is just beginning to affect their cognitive functioning.
1311
What are the symptoms of the intermediate stage of dementia?
Older or distant memory is gradually lost, and it becomes difficult to recover memories of events and people from earlier life.
1312
What are the symptoms of the most severe stage of dementia?
difficulty in putting thoughts into words, carrying out simple directed acts or recognizing well-known faces or objects. At this stage, the person must depend on others for basic activities of daily living.
1313
Why is Alzheimer's is dangerous?
because toxic changes occur in the brain at least 10 years before any cognitive problems or symptoms appear (the pre-clinical stage).
1314
During the pre-clinical stage, abnormal protein deposits begin to accumulate where in the brain?
proteins often accumulate first in the hippocampus and entorhinal cortex, areas of the brain essential for forming memories.
1315
What are the hippocampus and entorhinal cortex involved in?
forming memories
1316
What are the two main structural changes that occur in the brain in AD?
beta-amyloid plaques
| neurofibrillary tangles
1317
By the final stage of AD, damage is ___ and ___ has shrunk significantly. This is called __.
1. widespread
2. brain tissue
3. brain atrophy
1318
The ___ is a large membrane protein that has a key role in ___. As with all biomolecules, here is a potential for ___.
As an ___ is broken down by enzymatic processes, it splits into several forms, one form involved in AD being ___.
1. amyloid precursor protein
2. neural growth and repair.
3. abnormal function and corruption by disease
4. amyloid precursor protein
5. beta-amyloid 42
1319
What is a precursor?
A substance from which another is formed, especially by metabolic reaction
1320
Beta-amyloid 42, is thought to be especially ___ to the brain. In the Alzheimer’s brain, abnormal levels of this naturally occurring protein ___.
The collection of these plaques disrupts ___ by blocking ___. Additionally, beta-amyloid plaques are unable to be naturally dissolved by normal ___.
If cells can't communicate, power themselves, and are overrun by the build-up of beta-amyloid plaques, cortical ___ occurs as ___.
1. toxic
2. clump together to form plaques that collect between neurons
3. cell function
4. cell-to-cell signaling, impairing cell energy metabolism, and causing abnormal glucose regulation
5. clearance mechanisms
6. shrinkage
7. nerve pathways truncate and cells die off
1321
Neurofibrillary tangles are abnormal
___ that collect inside neurons.
Healthy brains have the tau protein to ___.
These structures, called microtubules, help ___.
In Alzheimer's Disease, abnormal chemical changes cause tau to ___, forming threads that eventually join to form ___ inside neurons.
These tangles block the ___, getting in the way of tau's original function of nutrient and transportation assistance. Neurofibrillary blockages harm the ___ by cutting off ___ to the ___.
1. accumulations of a protein called tau
2. stabilize internal structures in neurons
3. guide nutrients and molecules from the cell body to the axon and dendrites
4. detach from microtubules and stick to other tau molecules
5. tangles
6. neuron’s transport system
7. synaptic communication between neurons
8. nutrients
9. nerve endings at the tip of axons
1322
Essentially, there is a knock-on effect that the two main components of Alzheimer's Disease instigate:
Abnormal tau accumulates in specific brain regions involved in memory.
Beta-amyloid clumps into plaques between neurons.
As the level of beta-amyloid reaches a tipping point, there is a rapid spread of tau throughout the brain.
1323
In AD, the ___ have long been thought to be the main cause of dysfunction but there is now evidence that ___ may be better linked to the transition from the ___, or there may be a ___ and several other factors.
1. beta-amyloid plaques
2. tau protein
3. preclinical stage to mild AD
4. complex interplay among abnormal tau and beta-amyloid proteins
1324
In AD chronic inflammation is thought to occur from: What does these do in a healthy brain?
a buildup of the brain’s supporting cells, the glial cells.
| one type of glial cell, microglia, engulfs and destroys waste and toxins.
1325
We have a specific gene, ___, that normally triggers ___ to clear beta-amyloid plaques and help ___ in the brain. However, in AD, a mutation of this gene fails to ___, and as a consequence ___.
1. TREM2
2. microglia cells
3. fight inflammation
4. trigger microglia cells
5. plaques build up between neurons
1326
For people with Alzheimer's Disease, their microglia fail to:
clear away waste, debris, and protein collections, including beta-amyloid plaques.
1327
Astrocytes are signaled to help clear the buildup of plaques and other ___ that the ___ failed to remove. Unfortunately, the astrocytes' functioning has already been ___ by the presence of ___.
So there are then ___ collecting around neurons, yet they are unable to clear debris properly. As part of their default ___, they also release ___.
1. cellular debris
2. microglia cells
3. compromised
4. beta-amyloid plaques
5. microglia and astrocytes
6. immune response
7. chemicals that cause chronic inflammation and further damage the neurons
1328
In AD, chronic inflammation is a compounding of:
compromised cellular responses that leads to extensive neural decay.
1329
A number of problems that affect blood vessels, such as ___ may also be involved in AD.
This can reduce ___ to the brain.
Reduced blood flow and oxygen can cause a breakdown of the ___, which usually ___.
A faulty blood-brain barrier would ___ from reaching the brain and prevent the ___ - yet another cause of ___.
1. beta-amyloid deposits in brain arteries, atherosclerosis (hardening of the arteries), and mini-strokes
2. blood flow and oxygen
3. blood-brain barrier
4. protects the brain from harmful agents while allowing important things like glucose to enter.
5. prevent glucose
6. clearing away of beta-amyloid and tau proteins
7. harmful inflammation
1330
What is the amyloid precursor protein broken down by?
enzymatic processes.
1331
What is the name of the characteristic Huntington's symptom of involuntary jerking or twitching movements?
chorea
1332
There are also a number of mental and behavioural changes as early symptoms of the Huntington's disease.
Examples of cognitive changes include ___ later in the disease.
Emotional changes include ___. ___ may also be part of the disease.
1. forgetfulness/memory decline, difficulty making decisions and dementia
2. hostility/irritability and disinterest in things once important to the person
3. Delusions, hallucinations and paranoia
1333
Huntington's is a ___. It affects an estimated ___ per 100,000 people of European ancestry but is less common in some other populations, including people of Japanese, Chinese, and African descent.
1. progressive neurodegenerative disease
| 2. 3 to 7
1334
Huntington’s disease affects who?
both women and men, and people from two to 80 years of age.
1335
The most common form of Huntington's disease, ___, usually appears in a people aged in their ___.
Individuals with this onset usually live about ___ after signs and symptoms begin.
1. adult-onset HD
2. thirties or forties
3. 15-20 years
1336
The less common form of Huntington's disease, ___, which occurs in ___, tends to progress more quickly than the ___.
Affected individuals usually live ___ after signs and symptoms appear.
1. juvenile HD
2. childhood or adolescence
3. adult-onset form
4. 10-15 years
1337
Early symptoms of adult-onset HD include:
irritability, depression, small involuntary movements (chorea), poor coordination, trouble learning new information and making decisions, short-term memory lapses, and aggressive or anti-social behaviour.
1338
As Huntington's disease progresses, the chorea becomes ___, and results in difficulty ___.
1. more severe
| 2. walking, speaking and swallowing
1339
Other motor impairments of Huntington's disease (HD) include ___.
Changes occur in ___ state, as well as a ___ to think, reason, and concentrate on more than one thing at a time.
This has many ___ effects, including a ___.
1. slurred speech, difficulty swallowing or eating and loss of coordination/balance
2. personality and emotional
3. lowered ability
4. downstream
5. loss of drive, initiative, and organizational skills.
1340
In juvenile onset HD
Early on, movement problems (___) are common, as well as ___.
As the disease progresses, school performance ___ as thinking and reasoning abilities become ___.
Seizures occur in ___ of children with this condition.
1. slow movements, clumsiness, frequent falling, rigidity, slurred speech, drooling
2. mental and emotional changes
3. declines
4. impaired
5. 30-50 percent
1341
Huntington's Disease affects the ___, which controls ___, and the brain’s ___, especially ___ which serve as centres for ___.
1. basal ganglia
2. coordination
3. cortex
4. the executive function parts of the cortex
5. thought, perception, and memory
1342
In HD, the structures of the basal ganglia are ___, because of the ___ of the basal ganglia. Remember, the basal ganglia contain ___ nuclei, and the ___ is one of these nuclei.
As the striatum nerve cells are lost, there is a loss of ___. The ___ is affected more severely, at least at first, resulting in the ___ effect of less inhibitory output from the ___ of the basal ganglia - thus more stimulation of the ___. This is what gives rise to abnormal movements, such as ___.
1. a lot smaller than normal
2. death of nerve cells in the striatum
3. four
4. striatum
5. inhibitory output from the striatum
6. indirect pathway
7. downstream
8. output nuclei
9. motor cortex
10. chorea
1343
* Explain why those with HD experience a progressive loss of decision-making capability:
HD affects 2 main brain areas, the basal ganglia and the cortex. Specifically with the cortex, HD affects the executive function regions that are centers for decision-making, thought, memory and perception. As more neurons die in the executive regions, decision-making progressively deteriorate until normal function is lost.
1344
* Outline how the brain changes of HD affect motor control.
HD affects the basal ganglia, which is our centre for coordination. In particular, one of the nuclei of the basal ganglia, the striatum, experiences a death of nerve cells that decreases the size and function of that region.
As the striatum nerve cells are lost, there is a loss of inhibitory output from the striatum. The indirect pathway is affected more severely, at least at first, resulting in the downstream effect of less inhibitory output from the output nuclei of the basal ganglia - thus more stimulation of the motor cortex. This is what gives rise to abnormal movements- such as chorea.
1345
Huntington's disease is based around which specific gene?
HTT
1346
The HTT gene encodes for the ___, which is thought to be involved in ___, and protecting against programmed cell death (___).
1. the huntingtin protein
2. signaling, transporting materials, binding proteins and other structures
3. apoptosis
1347
In neurons, the huntingtin protein is primarily associated with ___, suggesting it has a role in ___ that give the cell ___ so it isn’t just a floppy water-filled bag. Huntingtin also has a role in the ___, the cell structures responsible for ___.
1. vesicles and microtubules
2. anchoring the structures
3. shape and structure
4. transport of mitochondria
5. cellular energy synthesis and storage
1348
The huntingtin protein is critical for ___: researchers have found that the ___ (and hence the huntingtin protein) is lethal in mice.
1. normal development before birth
| 2. absence of the HTT gene
1349
In Huntington's disease, mutations occur in the ___, which is on ___.
The ___ occur within a part of the gene known as a ___. In affected individuals, the CAG segment is repeated anywhere between ___ within the gene. In unaffected individuals, it is repeated ___.
1. HTT gene
2. chromosome 4
3. mutations
4. CAG trinucleotide repeat
5. 36-120 times
6. 10-35 times
1350
Individuals with 36
36
to 39
39
CAG repeats may or may not develop Huntington's, and those with 40
40
or more repeats will almost always develop it.
Individuals with ___ repeats do not develop HD, but are at risk of ___. This is because, as the gene is passed from parent to child, the ___ may lengthen into ___.
1. 27 to 35 CAG
2. passing it on to their children
3. size of the CAG trinucleotide repeat
4. the range associated with HD
1351
When the number of CAG trinucleotide repeats is in each of these ranges, what will the individual have?
27 - 35: No HD
36 - 39: may have HD
>40: HD
1352
___ of the CAG segment inside the ___ leads to production of an ___.
___ in the cell cut this ___ into fragments, but these fragments form ___ inside nerve cells, and attract other, ___ into the clumps.
The clumping disrupts the ___ of the cells and eventually leads to their ___.
___ in certain areas of the brain underlie what happens in ___.
1. Increasing the size
2. HTT gene
3. abnormally long version of the protein
4. Enzymes
5. elongated protein
6. abnormal clumps
7. normal proteins
8. normal functions
9. death
10. Dysfunction and eventual death of neurons
11. HD
1353
* Analyze how a child may inherit a mutated HTT gene and the likely effects it will have on the brain.
While individuals with 27-35 CAG repeats don't develop HD, when the gene is passed from parent to child, the size of the CAG trinucleotide may lengthen itself into the range associated with HD- for example a 35 CAG repeat could lengthen in a child over the 40 CAG repeat threshold for HD development.
When size of the CAG segment inside the HTT gene lengthens past the 40 threshold, it leads to production of an abnormally long version of the protein. Enzymes in the cell cut this elongated protein into fragments, but these fragments form abnormal clumps inside the nerve cells, and attract other, normal clumps into these clumps- turning into HD in the child.
At this point the clumping disrupts the normal cell function of the cells in the striatum and executive region of the cortex and eventually leads to neuronal death in the child's brain. The dysfunction and eventual death of neurons will cause chorea, memory and learning difficulties, aggressive behaviour, and in ability to regulate emotions and compromised decision-making.
1354
Autonomic functions are all critical to ___, which is the ability or ___ of organisms to ___ their ___ in a stable form.
Disruption of autonomic function can be ___, and even in less critical forms, ___ for patients.
1. homeostasis
2. tendency
3. self-regulate and maintain
4. internal environment
5. life-threatening
6. is socially embarrassing, life-disrupting and extremely frustrating
1355
what are dysautonomias?
dysfunctions of the autonomic nervous system
1356
the brain controls how we are and what we do through what 3 systems? What nervous systems relate to each of these?
skeletal muscles; The Somatic Nervous System
visceral muscle and tissues; The Autonomic Nervous System
hormonal tissues and glands; The Endocrine System
1357
___ is controlled by the Somatic Nervous System where nerves run to a ___. This allows for ___, point-to-point (i.e., ___ that very precisely controls specific ___), and ___ of our limbs and joints
1. Skeletal muscles
2. specific muscle or muscle group
3. precise
4. . brain output
5. muscle targets
6. fast control of skeletal muscles
1358
___ are controlled by the Autonomic Nervous System where nerves run (generally) to a number of ___ . This allows for ___ (i.e., brain output now runs to control many structures simultaneously), ___ (i.e., brain output now coordinates activity across many structures), and ___ control of tissues, glands and ___.
1. Visceral (internal) muscle and tissues
2. target tissues or organs
3. diffuse
4. integrative
5. integrative
6. smooth muscles
1359
___ is controlled through the Endocrine System where nerves don't run to the target tissues or organs. Instead they either ___. These hormones are then transported to affect ___ (the ones which have receptors for these hormones). This still for either ___ control of tissues, glands and organs.
1. Hormonal tissues and glands
2. release hormones or control the release of hormones into the blood.
3. target tissues and organs
4. tissue-specific or diffuse, integrative, and long term
1360
What is the fastest way for the brain to control the body?
The somatic nervous system
1361
What is an advantage of the ANS?
it allows many tissues and organs to be controlled simultaneously, to coordinate activity across these structures.
1362
what is the slowest system for controlling the body through the brain?
the Endocrine System- this system allows for long-term control
1363
Which nervous systems control autonomic function?
the ANS and endocrine system
1364
The ANS mediates relatively ___ using ___ of ___. These responses can be ___ or ___ across the body.
Therefore the ANS can exert widespread effects but do so in a way that is specific to the tissue under consideration.
The actions of the ANS can also be supplemented by the action of ___ which produce ___ and ___ tissues and organs might be affected.
1. rapid responses
2. direct nerve control
3. peripheral structures
4. specific to a target tissue
5. widespread
6. hormones
7. typically slow and diffuse effects
8. multiple
1365
To ___, the ANS is the pathway used to produce ___, in contrast to the ___ by using ___.
1. achieve homeostasis and allow activity
2. direct and relatively rapid neural control of internal organs
3. slower and longer-term control obtained
4. hormones
1366
Overall we can summarize the ANS as being a division of the Nervous System:
that is a ___ (i.e., widespread in where it acts) ___ that maintains ___ within the body and regulates the response of the body to its environment
through which effects can occur ___ without ___ (i.e., conscious) control and with little or no conscious awareness
whereby, often, effects are initiated in anticipation of a ___ or implemented so rapidly animal does not experience a ___.
that is linked to and coordinated with ___.
1. pervasive
2. neural network
3. homeostasis
4. routinely and automatically
5. volitional
6. perturbation
7. deficit
8. the somatic NS
1367
What are the 4 major advantages of the ANS?
1. Produces a relatively fast body response to perturbation
2. Coordinates activity across wide regions across the body
3. Has the capacity to be flexible in the types of responses that it produces
4. Acts on structures with intrinsic activity- It regulates activity of tissues and organs that have their own inherent activity.
1368
The ANS has two ___ in most ___ with ___ in most organs / tissues
1. motor divisions
2. organs/tissues
3. opposing effects
1369
The ANS has two ___ in most ___ with ___ in most organs / tissues
1. motor divisions
2. organs/tissues
3. opposing effects
1370
The ANS can release more than one ___ at ___, with ___ receptor for each transmitter, increasing the type of ___ it can produce.
1. neurotransmitter
2. targets
3. more than one
4. response
1371
In the ANS, ___ are released from many ___ at the same time or in addition to transmitters
1. modulator chemicals
| 2. terminals
1372
The ANS receives ___ to carefully ___ the ___.
1. continuous sensory feedback
2. modulate and refine
3. control of the targets
1373
for the ANS to perform the above tasks in an integrated manner, it has to:
receive ___ from ___ (which then allows ___ of the control system)
be integrated with ___ (to produce an overall control of ___), and
in addition, the ANS motor arm receives ___ (emotion, motivation, fear, etc) which are relayed from ___, and these ensure that the responses are appropriate to the wants and desires of the organism at the time. The CNS ___ all of these ___ and tweaks activity of the ANS.
1. feedback information
2. internal sensory systems
3. modulation
4. somatic and endocrine control systems
5. homeostasis and activity
6. higher order inputs
7. higher brain centres in the CNS
8. integrates
9. inputs
1374
The 3 components of the ANS neural loop are (in order):
1. a motor efferent arm
2. high-level integrative control
3. a sensory afferent arm
1375
We can localize the efferent motor neurons of the ANS consisting of two successive linked components, with a ___ originating in the ___ and then running to a ___ to contact a set of ___ that are the final arm for the ___ of tissues;
1. set of neurons
2. spinal cord and brain stem
3. ganglion
4. motor neurons
5. motor control
1376
We can localize the brain stem controllers of the first of the two neurons of the ___; these brain stem controller, in turn, get ___ from ___.
1. motor arm
2. controller or modulatory input
3. higher brain centres
1377
We can localise the sensory feedback from ___ going back to the ___ (___) or ___ (___).
1, target tissues
2. brain stem
3. non-nociceptive input
4. spinal cord and thalamus
5. nociceptive input
1378
The peripheral component of the ANS has what 2 arms?
```
an efferent (motor) arm
a afferent (sensory) arm
```
1379
What is the efferent (motor) arm in the peripheral ANS?
a set of motor nerve pathways running to control body structures
1380
What is the afferent (sensory) arm in the peripheral ANS?
a much more neglected set of sensory nerve pathways running back from body structures to provide feedback information used to refine the control and alter it to be appropriate for the tasks at hand or the desired outcomes.
1381
The efferent motor arm of the peripheral ANS is divided into what three divisions?
the Sympathetic Nervous system
the Parasympathetic Nervous Systems.
the Enteric Nervous system (ENS)
1382
What is the enteric nervous system (ENS)
a system of neurons functions solely to control the function of the gastrointestinal tract and is confined to the GI tract.
1383
The ENS can act independently of ___, although it may be ___.
1. the sympathetic and parasympathetic nervous systems
| 2. influenced by them
1384
The ___ arm has no such sympathetic / parasympathetic / enteric divisions and feedback is provided to both ___.
1. afferent
| 2. Sympathetic and Parasympathetic Nervous Systems
1385
The afferent arm feedback goes to the ___, to ___ that act as ___, and to the ___, located ___, which acts as ___.
1. ANS neurons’ cell bodies in the spinal cord
2. neuronal groups in the brain stem
3. controllers to the ANS neurons
4. hypothalamus
5. directly above the midbrain of the brainstem
6. an integrator for autonomic functions
1386
What is the function of the Sympathetic NS?
for sudden, perhaps stressful perturbation;
| the “flight or fight” response system,
1387
What is the function of the Parasympathetic NS?
for housekeeping;
| the “rest and digest” response system.
1388
The two ANS branches (excluding the ENS) often exert:
an opposing (antagonistic) effect on many different organs and systems.
1389
What does the Parasympathetic NS drive?
Rest, Recover & Relax processes
1390
What does the Sympathetic NS drive?
Fight, Flight or Fright responses
1391
In some areas of the body, the two main ANS divisions work ___ (not antagonistically) to achieve the ___ (eg: ___).
1. synergistically
2. end output
3. the sexual response
1392
In some other areas, there is ___ from only one of the main ANS divisions, for example:
the adrenal medulla receives only ___.
Most blood vessels in the body do not have ___.
however, ___ salivary glands, gastrointestinal glands, genital erectile tissue, and skin blood vessels, where they ___.
1. innervation
2. sympathetic input
3. parasympathetic innervation
4. parasympathetic nerves do innervate
5. act on blood vessels
1393
it’s best to view the two main ANS systems as operating in a ___:
The Sympathetic division allows the ___, while the Parasympathetic division helps ___.
1. synergistic manner
2. conduct of activity
3. recuperate and build up energy stores
1394
The ANS motor arm is a ___ from the ___ to the body structure controlled by the ___.
1. two-neuron system
2. Central Nervous System (CNS)
3. ANS motor arm
1395
In the ANS:
The first neuron has its cell body located in the CNS:
in the ___ (only for the ___)
or in ___ (for ___).
1. brainstem
2. Parasympathetic division
3. the spinal cord
4. both Sympathetic and Parasympathetic divisions
1396
The first ANS neuron is called the ___, as it’s axon runs to a ___ where it then ___ with the second neuron in the chain, ___.
The ___ of the post-ganglionic neuron then runs from the ganglion to the ___.
1. preganglionic neuron
2. ganglion
3. synapses
4. the post-ganglionic neuron
5. axon
6. target tissue
1397
In the control of skeletal muscle, the ___ in the brainstem or ___ sends the final CNS output directly to the ___.
This is fast - there is ___ between this α motor neuron and the target skeletal muscle.
1. α (alpha) motor neuron
2. spinal cord
3. target (skeletal muscle)
4. nothing
1398
In the control of visceral structures by the ___, the ___ from the CNS is a ___ from the CNS, as follows:
CNS → ___ → ___ to ___.
this intervening stop will ___ on the target tissue.
1. ANS
2. motor output
3. two-neuron chain
4. Pre-ganglionic neuron in Ganglion
5. Postganglionic neuron
6. Target tissue
7. slow the end result
1399
Although the two-neuron chain in the ANS ___ control of body systems, it allows ___ at the stop point (___).
1. slows down
2. integration of many inputs
3. the ganglion
1400
Control of internal organs rarely ever needs to be ___.
In contrast, moving your body to correct for a sudden dip in the terrain or for an uneven terrain is something that needs ___ to prevent you from c___.
So control of the skeletal muscles (___) always has to have ___.
1. done quickly
2. to be done quickly
3. to be done quickly
4. the Somatic Nervous System
5. the capacity to be fast
1401
The cell bodies of the pre-ganglionic neurons are located where?
1. in the Thoracic and Lumbar (T1 - L3) regions of the spinal cord
1402
The sympathetic pre-ganglionic cell bodies receive ___ from centres in ___.
Input to them from ___ is comparatively ___.
Thus, their main control is from ___, not through reflexes from ___ (i.e., the ___ of the body).
1. controlling inputs
2. the midbrain and the brain stem
3. spinal reflexes
4. minor
5. higher regions of the brain
6. sensory input from the periphery
7. tissues and organs
1403
Parasympathetic pre-ganglionic neuronal cell bodies are located where?
in the brainstem or in the Sacral (S1 - S3) region of the spinal cord.
1404
The axonal output of parasympathetic preganglionic neurons will differ according to what?
where the cell bodies are located.
1405
For neuronal cell bodies in the Brainstem, the axons run in the cranial nerves, specifically:
Cranial Nerve ___ (Occulomotor nerve; to the eye);
Cranial Nerve ___ (facial nerve; to submandibular and sublingual salivary glands);
Cranial Nerve ___ (glossopharyngeal nerve; to parotid gland);
Cranial Nerve ___ (vagus nerve; a number of structures from from neck to waist), and
Cranial Nerve ___ (accessory nerve) (from neck to waist).
1. III
2. VII
3. IX
4. X
5. XI
1406
For neuronal cell bodies in the Sacral spinal cord, the axons run where?
in the Sacral spinal nerves (S2-S4) to the pelvic organs.
1407
In both cases of the parasympathetic NS, the axons run to ___ which lie ___
1. ganglia
| 2. within or just beside the tissue.
1408
In both cases of the parasympathetic NS, the axons run to ___ which lie ___
1. ganglia
| 2. within or just beside the tissue.
1409
In both cases of the parasympathetic NS, the axons run to ___ which lie ___
1. ganglia
| 2. within or just beside the tissue.
1410
This lack of any branching allows the ___ to exert more ___ than exerted by the ___.
1. Parasympathetic NS
2. localized effects
3. Sympathetic NS
1411
Axons of the postganglionic neurons run from the ___ to organs in ___.
1. sympathetic chain ganglia
| 2. the face or in the thoracic, abdominal or pelvic cavities.
1412
Compared to the sympathetic division, in the parasympathetic division:
parasympathetic pre-ganglionic nerves are longer,
have the ganglion lying near the target tissue or organ,
and therefore have shorter post-ganglionic nerves
1413
the ANS has a ___ from the ___ to ___
whereas
the Somatic Nervous System has a ___ in the ___ sending the ___ directly to ___.
1. two-neuron system
2. CNS
3. the tissue
4. single α (alpha) motor neuron
5. brainstem or spinal cord
6. final CNS output
7. the target skeletal muscle
1414
the two fastest classes (___) of motor neurons are NOT associated with ___ but with ___ - that is, they are associated with ___.
1. the two A classes
2. the ANS
3. control of skeletal muscle
4. the Somatic Nervous System
1415
It's the two ___, (___), that are associated with ___:
The faster of these two (B) is ___ in the ANS, and the slowest class of neurons (C) is ___ in the ANS.
1. slowest classes of neurons
2. B and C
3. the ANS
4. the preganglionic neuron
5. the post-ganglionic neuron
1416
the ANS is not a system that allows for rapid control of targets:
The preganglionic neurons are ___ down their length.
When that information gets to the ends of the neuron (___), it doesn't get relayed to ___.
Instead, it gets relayed to another neuron, ___ to ___.
The postganglionic neuron is even ___ than the preganglionic neuron.
So eventually the control is exerted on the target tissue.
1. slow at transmitting information
2. the terminals
3. control targets
4. the post-ganglionic neuron
5. the target
6. slower at transmitting information
1417
When neurons signal information to a separate cell (another neuron, or a muscle, or a tissue, etc), they release ___.
These chemical transmitters need to have ___ for them to ___ to and only then can they ___.
1. chemicals called transmitters
2. receptors on the target cell
3. bind
4. exert an effect
1418
What are ionotropic receptors?
| What do they do?
Receptors that produce rapid effects in the target cell after they bind the transmitter.
They control the movement of ions through them, from one side of the cell membrane across to the other side.
1419
Why do ionotropic receptors produce rapid electrical changes in the target cell?
Since ions move quickly, and since ions carry charge
1420
In the ANS, the chemical transmitter used by the preganglionic neurons, of either ___ of the ANS, to transmit information to ___, is a transmitter that binds to ___.
So transmission of information from the pre-ganglionic neuron to the post-ganglionic neuron is ___.
1. the Sympathetic division of the ANS or the Parasympathetic division
2. the post-ganglionic neuron
3. ionotropic receptors on the post-ganglionic neuron
4. fast
1421
What are metabotropic receptors?
| What do they do?
Receptors produce slow effects in the target cell after they bind the transmitter, because they then need to activate other molecules in the cell and only then do changes occur in the target cell to acknowledge that information has been received from the transmitting cell.
1422
What do metabotropic receptors produce?
slow metabolic changes (which can lead to later electrical changes) in the target cell.
1423
In the ANS, the chemical transmitter used by the post-ganglionic neurons, of ___ of the ANS, to transmit information to ___, is a transmitter that binds to ___.
So ___ from the the post-ganglionic neuron to the target tissue is ___.
1. either the Sympathetic division of the ANS or the Parasympathetic division
2. the target tissue
3. metabootropic receptors on the target cell
4. transmission of information
5. slow
1424
Both ANS divisions use the same transmitter between ___, one called ___.
1. the preganglionic neuron and the post-ganglionic neuron
| 2. Acetylcholine and abbreviated ACh
1425
In both ANS divisions, ACh binds to an ___ on the ___, called ___.
1. iontropic receptor
2. post-ganglionic neuron
3. nAChR
1426
The Parasympathetic division still uses ___ to transmit information from the ___ to the tissue, but it binds to a ___, called ___, on the ___.
1. ACh (Acetylcholine)
2. post-ganglionic neuron
3. metabotropic receptor
4. mAChR
5. target tissue
1427
The Sympathetic division uses a different transmitter, ___, to transmit information from the ___ to the tissue and it binds to , ___, on the target tissue.
1. Noradrenaline and abbreviated NA
2. post-ganglionic neuron
3. metabotropic receptors
4. alpha ARs or beta ARs
1428
what higher brain centres send controlling inputs to preganglionic neurons?
1. The Hypothalamus (for Integrative control)
| 2. The Medulla (for Reflexive control)
1429
In the ANS, what is the hypothalamus involved in?
Integrative control
1430
In the ANS, what is the medulla involved in?
reflexive control
1431
In the ANS the medulla, and the hypothalamus in particular, receive inputs from other higher regions, specifically ___. So this provides a route where our ___ can be implemented with appropriate changes in the state of our ___.
1. the Cortex, Limbic System and Thalamus
2. desires and wishes
3. internal organs and tissues
1432
What is the Master Integrator of internal body function?
The hypothalamus
1433
Within the brain, the ANS is regulated by ___: ___ located ___.
The different ___ have varied functions – e.g., ___
1. the hypothalamus
2. a cluster of small nuclei
3. just above the brain stem and just below the thalamus
4. hypothalamic nuclei
5. homeostasis, feeding, drinking, reproduction.
1434
In the ANS, one of the most important functions of the hypothalamus is to link do what?
link the nervous system to the endocrine system via the pituitary gland.
1435
The hypothalamus acts as ___, receiving ___ as well as ___ from a number of ___ so that body function can be ___ but also in response to ___.
1. an integrator for autonomic functions
2. ANS feedback input
3. ANS regulatory input
4. higher brain structures
5. adjusted unconsciously
6. voluntary desires
1436
The hypothalamus controls the body over ___ (ANS) or ___ (Endocrine) time scales, essentially through two main ___ from hypothalamus:
- ___ - Lateral hypothalamus projects to (lateral) ___, including ___ as well as cell groups that descend to ___, eg: ___
- ___ - to release ___, or to release ___ into ___, to cause secretion of any one of at least ___ hormones.
1. moderate
2. long
3. outputs
4. neural signals to ANS controller nuclei in the brainstem
5. medulla
6. parasympathetic (vagal) nuclei
7. sympathetic system in spinal cord
8. control heart rate, vasoconstriction, digestion, sweating, etc.
9. endocrine signals to/through the pituitary
10. hormones (posterior pituitary
11. releasing factors (from base of pituitary)
12. blood supply to anterior pituitary
13. six
1437
An important hypothalamic nucleus for ANS control is the ___.
This is an important nucleus because it is ___.
1. paraventricular nucleus(PVN)
| 2. connected to many brain areas
1438
The PVN is the only brain site in a ___ with both sympathetic and parasympathetic ___ of the ANS (meaning that it receives feedback about ___, and uses that feedback to ___ both divisions of the ANS motor arm).
Other brain areas may be in a closed reflex loop with only ___.
1. closed reflex loop
2. motor divisions
3. the effects of both divisions of the ANS motor arm
4. control
5. one components of the ANS, but not both
1439
In the PVN, there is a special group of what? for what?
Parvocellular neurons for central autonomic control.
1440
Parvocellular neurons in the ___ send their axons to both sides of the brain - though predominantly on the ___, to:
___ of the ___,
or even directly to the parasympathetic and sympathetic ___ in the ___.
1. PVN
2. same (ipsilateral) side
3. brainstem nuclei
4. parasympathetic and sympathetic systems
5. preganglionic neurons
6. spinal columns
1441
The PVN also integrates feedback from ___ directly via the ___ (the feedback arm ___ in our ___) and from the ___ which receives most of the ___.
1. both ANS motor divisions
2. feedback afferents
3. 3
4. neural loop
5. Nucleus of the Solitary tract (NTS)
6. ANS afferent feedback input
1442
While the PVN is the one we've focused on, at least ___ other ___ are also involved in ___.
They send to and receive ___ from the ___, ___, and the ___.
The Lateral hypothalamus is especially involved in ___.
1. 5
2. hypothalamic nuclei
3. hypothalamic control of the ANS
4. projections
5. PVN
6. the brainstem nuclei of the ANS
7. sympathetic preganglionic neurons in the spinal columns
8. CVS control and control of feeding, satiety and insulin release
1443
A critical core function of the hypothalamus is ___.
This is only possible if it gets ___ about the ___, as well as inputs about ___ (so that homeostasis can be maintained in the face of ___).
1. homeostasis
2. as many inputs as possible
3. internal state of the body
4. what the organism desires to do
5. changing demands
1444
Inputs to the hypothalamus for control/integration of the ANS include:
___- which collects and relays all sensory input from internal organs (e.g., BP, gut distension) from the Vagus Nerve (the Xth cranial nerve)
___ - brainstem nuclei that receive various inputs from spinal cord, including skin ToC.
___ send inputs to the hypothalamic suprachiasmatic nucleus (SCN) to regulate circadian rhythms relative to light/dark cycles (the SCN is also known as the body's master clock).
___ - monitor blood - e.g., osmolarity (OVLT), toxins (area postrema which can induce vomiting)
___ - provide inputs that regulate behaviors like eating and reproduction.
___ - thermoreceptors that monitor blood temperature and osmoreceptors that monitor fluid and electrolyte balance.
1. Brainstem nucleus of solitary tract (NTS)
2. Reticular formation
3. Retina - Optic Nerve fibers
4. Circumventricular nuclei
5. Limbic and Olfactory systems
6. Receptors within the hypothalamus itself
1445
the hypothalamus is regarded as the master integrator of:
inputs and outputs relevant to the internal body state.
1446
The ANS is the ___ of the ___, not a separate system on it's own that happens to be linked to the hypothalamus.
1. neural arm
| 2. hypothalamus
1447
For homeostasis to be achieved, ___.
Further, changes need also to be able to be implemented under.
Thus ANS processing has to be ___ and has to involve structures across ___.
Finally, for a complete integrative control system, there must be ___ so it can be properly responsive to ensure that the ___ have been implemented.
So, add in ___, and flow between ___.
1. a number of internal states have to be co-regulated
2. voluntary desire
3. highly integrative
4. multiple levels of the CNS
5. multiple points of feedback
6. right changes
7. neuronal outflow from the medullary nuclei to the Hypothalamus
8. brainstem (to and from) and the spinal cord
1448
In the brainstem, the ___ in particular contains many nuclei controlling ___ via ___.
These nuclei receive input from ___ located at various points along the body and brain, to trigger ___ in ___.
1. medulla
2. ANS function
3. descending axons to Sympathetic and Parasympathetic preganglionic neurons
4. receptors
5. reflex changes
6. visceral organs and tissues
1449
The nuclei in the medulla controlling ANS function include:
* ___– controls stress and panic responses (Cardiovascular, CVS; respiratory; motor; vomiting, satiety, self-satisfaction, addiction responses);
* ___ – major outflow to sympathetic pre-ganglionic neurons for excitation of the CVS (resting and reflex control of the CVS) and control of respiration;
* ___ - blocks RVLM (blocks CVS excitation) and sends outputs to the spinal cord for control of pain responses (integration of nociceptive, cardiovascular, and motor functions);
* ___ - emetic centre (induces vomiting)
* ___ (controls urination)
1. The LC (Locus coeruleus)
2. Rostral ventrolateral medulla (RVLM)
3. Caudal ventrolateral medulla (CVLM)
4. Area postrema
5. Micturition centres
1450
To be most effective, control of the body systems by the ANS needs to ___.
Unlike the motor arm, this sensory feedback is not divided into ___.
The feedback may (sometimes) go only to ___, or (more commonly) ___.
The adjustments made in ___ will influence ___ Sympathetic and Parasympathetic divisions.
1. receive feedback from different internal structures
2. Sympathetic and Parasympathetic divisions
3. sympathetic controller nuclei or parasympathetic controller nuclei
4. both
5. response to the feedback
6. both
1451
Sensory information from visceral organs is detected by what?
1. receptors found on free nerve endings
1452
The nerve endings of visceral receptors are those of two classes of nerve fibres:
___
___
These two classes of nerve fibres are ___, and so they transmit information to the brain more slowly than ___ of nerve fibres that carry information in the ___ (except for pain information which is also carried by ___).
1. thin, unmyelinated axons (C fibres)
2. larger, myelinated A-delta fibres.
3. slowly conducting classes
4. the Aα and Aβ classes
5. somatic systems
6. A-delta and C fibres
1453
visceral structures are classified as:
non-discriminative
1454
The Vagus Nerve provides a huge amount of ___.
The Vagus Nerve is cranial nerve ___
This nerve is a ___ (like a spinal nerve) which means it is composed of ___.
1. non-nociceptive ANS sensory information
2. X
3. mixed nerve
4. sensory as well as motor nerves
1455
The visceral sensory component (i.e., the sensory nerve fibres coming from the viscera, or internal organs) of the Vagus Nerve carries ___ from:
___ (of the respiratory system)
___ (respiratory and gastrointestinal systems),
___ (blood pressure monitors),
___ (monitors of the state of gases and pH in the blood).
Sensory axons, of afferent neurons with cell bodies lying in the ___, from different sites join the ___ at different levels and in complex ways.
Cell bodies of the ___ are located in the Inferior Vagal Ganglion, their axons run – on one side from the cell body – ___ and- on the other side from the cell body – ___.
1. sensory input
2. the larynx, esophagus, trachea
3. abdominal and thoracic viscera
4. stretch receptors of the aortic arch
5. chemoreceptors of aortic bodies
6. Inferior Vagal Ganglion
7. left and right Vagus Nerves
8. afferent neurons
9. to the viscera
10. to the medulla
1456
NS non-nociceptive (non-pain) Sensory input flows to ___ in the ___.
The Nucleus Tractus Solitarius (the NTS) is the most important ___ getting ANS ___.
1. Nucleus Tractus Solitarius (NTS)
2. Medulla
3. medullary (lower brainstem) nucleus
4. sensory inputs
1457
The NTS contains the neurons that receive ___ ANS inputs:
___ (pH, pO2, pCO2),
___ (e.g., stomach distension) input,
and ___ (blood pressure) input.
The NTS also receives other sensory inputs from ___, brought in by the cranial nerve IX (___), cranial nerve VII (___) & cranial nerve V (___).
Different types of inputs are ___ - different ___ are devoted to respiratory, cardiovascular, gastro-intestinal and taste inputs.
1. non-nociceptive
2. all peripheral chemoreceptor
3. visceral mechanoreceptor
4. baroreceptor
5. internal organs
6. glossopharyngeal nerve
7. facial nerve
8. trigeminal nerve
9. not mixed
10. NTS sub-nuclei
1458
The NTS sends its ___ to many other brain sites
From the NTS neurons that get the ANS ___, axons are sent ___ to several nuclei in ___.
The impact is to evoke many other ___ from ___.
1. outflow
2. sensory inputs
3. bilaterally
4. the brainstem and hypothalamus.
5. responses or outcomes
6. internal sensory input.
1459
The NTS outflow to other brainstem ANS controller nuclei and to the Hypothalamus allows for ___ of ___. These reflexes evoke the ___ through ___ that come from neurons in the ___ (Cranial Nerve ___).
The NTS outflow to the Thalamus is sent on to ___ for ___.
The NTS outflow to the Limbic system generates ___.
1. reflex (unconscious) control
2. the cardiovascular system , respiratory, and gastrointestinal functions
3. visceral responses
4. motor axons
5. Dorsal Motor Vagus nuclei
6. X
7. the cortex
8. conscious awareness of internal states
9. emotional outcomes from internal sensations
1460
What is a mixed nerve?
A nerve consisting of sensory as well as motor nerves
1461
The more signals sent between two neurons:
the stronger the connection grows
1462
the interactions of neurons is:
electrochemical
1463
Each axon terminal contains thousands of membrane-bound sacs called ___, which in turn contain thousands of ___ each.
1. vesicles
| 2. neurotransmitter molecules
1464
Neurotransmitters are what?
chemical messengers which relay, amplify and modulate signals between neurons and other cells.
1465
what glial cells has an active role in brain communication and neuroplasticity
astrocytes
1466
he cerebrum is covered by a sheet of neural tissue known as what?
the cerebral cortex (or neocortex)
1467
What are the 4 lobes of the cerebral cortex? What are they involved in?
```
frontal lobe (involved in conscious thought and higher mental functions, processing short-term memories and retaining longer term memories which are not task-based) the parietal lobe (involved in integrating sensory information from the various senses, and in spatial sense and navigation);
the temporal lobe (involved with the senses of smell and sound, the processing of semantics in both speech and vision, including the processing of complex stimuli like faces and scenes, and plays a key role in the formation of long-term memory);
and the occipital lobe (mainly involved with the sense of sight).
```
1468
What part of the brain is involved in declarative and episodic memory?
the medial temporal lobe
1469
the establishment of long-term memory involves a process of physical changes in the structure of neurons (or nerve cells) in the brain, a process known as:
long-term potentiation
1470
What are procceses?
axons and dendrites
1471
What are ion channels?
Pores in the axonal membrane that open and close to let through electrically charged atoms (ions)
1472
What is the Part of the brain stem, controls the activity of higher neurons in functions such as sleep, attention and reward
Midbrain
1473
What part of the diencephalon, relays information from all sensory systems to the cerebral cortex and vice versa
thalamus
1474
what part of the diencephalon, controls functions such as eating and drinking; regulates the release of hormones
hypothalamus
1475
what is the brief period after a synaptic transmission in which no action potentials travel along the nerve?
refractory period
1476
What are molecules that influence the expression of neuronal genes and therefore the manufacture of new proteins?
growth factors
1477
what is the main excitatory neurotransmitter in the brain?
glutamate
1478
what are the 3 parts of the forebrain?
cerebrum, thalamus, hypothalamus
1479
functions of the forebrain:
processing and storing memory and information
1480
Functions of the midbrain:
movement, auditory, and visual processing
1481
what are the 3 parts of the hindbrain?
pons, medulla oblongata and cerebellum
1482
How many photoreceptors do we have?
125 million (120 million rods, 6 million cones)
1483
what lobe is the primary visual cortex located?
the occipital lobe
1484
what forms the optic nerve?
axons of ganglion cells
1485
What is the part of the brain that contains the auditory cortex?
superior temporal gyrus
1486
What type of touch do Ruffini endings respond to? Where are they?
Slowly changing indentations
| Deep in the skin
1487
What type of touch do Merkel's disks respond to?
sustained indentation (pressure)
1488
What type of touch do Pacinian and Meissner corpuscles respond to?
Vibration and flutter
1489
What touch receptor is closest to the surface of the skin?
Meissner's corpuscle
1490
What happens in hyperalgesia?
the pain threshold is lowered
1491
Lobe that is involved with sensory processes, attention, and language:
parietal lobe
1492
Threshold voltage for action potential to occur?
-55mV
1493
What do the pons and medulla oblongata do?
Respiration, blood pressure, heart rhythms, blood glucose levels
1494
Where are neurotransmitters stored?
Synaptic vesicles at the end of axons
1495
Negative ion in an action potential
Cl-
1496
What is the process that triggers ectoderm cells to become nerve tissue?
Neural induction
1497
2 inhibitory neurotransmitters:
GABA, glycine
1498
What does caffeine do?
Antagonizes adenosine receptors
1499
Size of synaptic cleft:
20nm
1500
2 classes of receptors:
Ionotropic
| metabotropic
1501
What are ionotropic receptors connected to that metabootropic receptors are not?
ion channels
1502
3 types of catecholamines
Dopamine, norepinephrine, epinephrine
1503
What does the neural plate fold to become?
the neural tube
1504
How many cells are in the human brain
1 billion
1505
The ion that enters axon terminals after an action potential
Ca 2+
1506
The ion that enters axon terminals after an action potential
Ca 2+
1507
The neurotransmitter acting in the neuromuscular junction
acetylcholine
1508
Through what pathway do touch impulses enter the spinal cord?
Dorsal roots
1509
What is a motor unit?
An Alpha motor neuron and the muscle fibres it contains
1510
2 types of reflexes:
withdrawal and stretch
1511
2 parts of the eye that light is focused by:
lens
| cornea
1512
What is the conversion of light into electrical signals?
Phototransduction
1513
Which lobe is responsible for hearing, learning and feelings?
Temporal lboe
1514
What is the cerebellum responsible for?
balance and coordination
1515
What is the frontal lobe responsible for?
Thinking, memory, behaviour and movement
1516
Function of the hypothalamus
Eating and drinking, hormone release
1517
What happens to neurotransmitters once they've done their job?
Either broken down by enzymes, get re-uptaken to the axon terminal, or diffuse away
1518
What does an EMG (electromyogram) do?
Measures electrical activity of the muscles
1519
Function of Broca's area
Controls facial neurons, speech and language
1520
Where is Broca's area?
left frontal lobe
1521
Function of Pituitary gland
Secretes hormones to all other adrenal glands
1522
Olfactory bulb
Regulates sensation of smell
1523
What is neuromodulation?
Process by which nervous activity is regulated by controlling the levels of neurotransmitters
1524
What does the LGN do?
disperses optic signals
1525
Two structures involved in skill and physical learning?
Cerebellum and basal ganglia
1526
Which neurotransmitter helps with organization during stress?
Noradrenaline
1527
What does ATP stand for?
Adenosine triphosphate
1528
he outer membrane of a neuron consists of:
fatty substances draped around a cytoskeleton
1529
Dendrites have contacts with between how many neurons?
1-1000
1530
currents that move out of the cell:
inhibition
1531
currents that come into the cell:
excitation
1532
what part of the brain controls fine motor skills?
the cerebellum
1533
Thalamus function:
All ascending sensations pass through on way to cerebral cortex except olfactory
1534
the corpus callosum is:
a large band of neural fibers connecting the two brain hemispheres and carrying messages between them
1535
Ion pumps do what;
Bail out excess sodium ions
1536
What layer of the skin are Meissner's corpuscles located in?
the dermis
1537
what is a receptive field?
the area from which our receptor cells receive input
1538
What is phototransduction?
Conversion of light energy into neural impulses
1539
What is the optic tract?
How information from the optic nerve travels to the thalamus.
1540
What is a presynaptic protein?
Proteins that cause the synaptic vesicles to release the neurotransmitters
1541
What are receptors?
nerve cells that detect conditions in the body's environment
1542
What do metabotropic receptors do?
carry out neuromodulation
1543
Binocularity:
Ability of the eyes to function together.
1544
parietal neglect:
failure to notice objects
1545
cell differentiation:
the process by which a cell becomes specialized for a specific structure or function.
1546
What is neuroplasticity?
Ability of brain tissue to modify itself and take on new functions.
1547
what is long term potentiation?
gradual strengthening of the connections among neurons from repetitive stimulation
1548
long term depression
decrease in synaptic strength
1549
what is working memory
active maintenance of information in short-term storage
1550
what does the central executive system do?
controls deployment of attention
1551
what is phonological store?
a passive store component of the phonological loop
1552
When an action potential is generated, the first ion channels to open are the:
sodium channels
1553
Action potentials can travel at:
100m/s
1554
Pacinian corpuscles have ___ fields than Meissner's corpuscles
larger
1555
Area V5 is involved in:
motion detection
1556
What are the types of Glutamate receptors?
AMPA and NMDA
1557
How much does the brain weight?
1.5kg
1558
The basal ganglia is located:
Beneath the cortex in cerebral hemispheres
1559
AMPA receptors are ___ than NMDA receptors.
faster
1560
At rest ___ ions can cross through the membrane easily whereas ___ ions have a more difficult time crossing.
1. potassium
| 2. sodium
1561
There is a pump that uses energy to move ___ sodium ions out of the neuron for every ___ potassium ions it puts in. The resting membrane potential of a neuron is about ___ mV (mV=millivolt) - this means that the inside of the neuron is
___ mV less than the outside. At rest, there are relatively ___
sodium ions outside the neuron and ___ potassium ions inside that neuron.
1. three
2. two
3. -70
4. 70
5. more
6. more
1562
An action potential occurs when a neuron sends information down an ___, away from the ___.
The action potential is an ___ that is created by a ___. This means that some event (a stimulus) causes the resting potential to move toward ___. When the depolarisation reaches about ___, a neuron will fire an ___. This is the ___. If the neuron does not reach this critical threshold level, then no action potential will ___.
1. axon
2. cell body
3. explosion of electrical activity
4. depolarising current
5. 0 mV
6. -55mV
7. action potential
8. threshold
9. fire
1563
Action potentials are caused when different ions cross the ___. A stimulus first causes ___ to open. Because there are many more sodium ions on the ___, and the inside of the neuron is ___ relative to the outside, sodium ions rush into the neuron. Sodium has a positive charge, so the neuron becomes more positive and becomes ___.
1. neuron membrane
2. sodium channels
3. outside
4. negative
5. depolarised
1564
It takes longer for___ to open. When they do open, potassium rushes ___ the cell, ___. Also at about this time, sodium channels start to ___. This causes the action potential to go back toward ___ (___). The action potential actually goes past -70mV (___) because the ___ channels stay open a bit too long. Gradually, the ion concentrations go back to ___ and the cell returns to -70mV
1. potassium channels
2. out of
3. reversing the depolarisation
4. close
5. -70mV
6. repolarization
7. hyperpolarization
8. potassium
9. resting levels
1565
Neurotransmission, also called synaptic transmission, is the process by which:
signaling molecules called neurotransmitters are released by a neuron (the presynaptic neuron), and bind to and activate the receptors of another neuron (the postsynaptic neuron).
1566
A neurotransmitter is a ___ that ___ signals between neurons and other cells in the body. Neurotransmitters are stored in ___ clustered beneath the membrane in the ___ located at the ___.
1. chemical messenger
3. synaptic vesicles
2. carries, boosts and modulates
3. axon terminal
4. presynaptic side of the synapse
1567
In response to an action potential reaching the synapse, neurotransmitters:
are released into and diffused across the synaptic cleft, where they bind to specific receptors in the membrane on the postsynaptic side of the synapse. This binding of receptors triggers a process called signal transduction.
1568
What is signal transduction (cell signalling)?
the transmission of molecular signals from a cell's exterior to its interior. Signals received by cells must be transmitted effectively into the cell to ensure an appropriate response. This step is initiated by cell-surface receptors.
1569
Signal transduction occurs when ___ activates a specific receptor located on the ___. In turn, this receptor triggers a ___, creating a response. The signal can be ___ at any step. Thus, one signaling molecule can cause many responses.
1. an extracellular signaling molecule (neurotransmitter)
2. cell surface or inside the cell
3. chain of events inside the cell
4. amplified
1570
What are the 3 layers of the skin (most to least exterior)
epidermis, dermis, hypodermis
1571
in the involuntary nerve pathway, what do interneurons send electrical impulses to?
motor neurons
1572
What is the cornea?
The cornea is the transparent skin that covers the front of your eye.
1573
What does the choroid do?
Contains blood vessels, which bring nutrients to the eye.
1574
What does the sclera do?
Protects the eye and helps it maintain its shape.
1575
How many nerve cells does the brain contain?
86 billion
1576
Sensory circuits:
carry signals from sense receptors to your
| brain.
1577
Motor circuits:
send commands to
| your muscles.
1578
Simple circuits:
carry out
| your automatic reflexes.
1579
Higher-level activities like ___ require ___.
1. memory, decision-making, and perceiving the world
around you
2. complex circuits
1580
You’ve had most of the neurons in
your brain since ___. Most of those will
stick around for ___, yet
your brain is ___ — neuroscientists call this ___. Learn a new skill or language and your brain reacts by
___ — even creating new ones.
Each new experience shapes your brain to
become uniquely yours.
1. birth
2. the rest of your life
3. the rest of your life
4. constantly changing
5. plasticity
6. strengthening or weakening the connections
between neurons
1581
Compared with other animals, the human brain possesses an enormous ___ that is brimming with ___ dedicated to language.
1. cerebral cortex
| 2. neural circuits
1582
Neurological diseases/disorders affect what percentage of people.
25% (1 in 4 people)
1583
```
The surface of the cerebrum is
a ___ called the ___. Its deep
folds increase the ___ of the cerebral
cortex, creating space in this surface
layer for more ___, which increase
the brain’s ___.
```
1. deeply folded layer of nerve tissue
2. cerebral cortex
3. area
4. neurons
5. processing power
1584
Neurons can be:
excitatory
| inhibitory
1585
What is the most common type of excitatory neuron?
pyramidal cell
1586
What percentage of neurons are excitatory?
80%
1587
What do inhibitory neurons do?
send signals that suppress the activity
of neighboring neurons and regulate
the activity of a circuit
1588
Every neural circuit contains both
| ___ neurons.
1. excitatory and inhibitory
1589
Excitatory neurons tend to be:
Pass signals forward
through a circuit and eventually send
outputs to other parts of the brain.
1590
In feedback inhibition, neurons send signals to their
___ and to ___ that reach back and
inhibit preceding layers of the same
circuit.
1. downstream excitatory neighbors
| 2. interneurons
1591
The ratio of neuron to glia is close to ___ in primates. However, it ___ from region to region varies
considerably
1. 1:1
| 2. varies
1592
When an action potential arrives at the ___, the voltage
change triggers ion channels in the membrane to ___, which lets ___ flow into the cell. When the
calcium ions bind to packages of ___ called ___, the vesicles fuse with the ___ at the axon terminal and
empty their contents into the ___.
1. axon terminal
2. open
3. calcium ions
4. neurotransmitter molecules
5. synaptic
vesicles
6. cell membrane
7. synaptic cleft
1593
Golgi apparatus:
the cell’s protein-packaging organelle
1594
After neurotransmitters are released from an ___,
they drift across the ___ until they reach the outer surface of the ___. This region, the ___, has a high concentration of ___.
1. axon terminal
2. synaptic cleft
3. dendrite
4. postsynaptic density
5. neurotransmitter receptors
1595
What is reuptake?
When, once they detach, the ion
channels return to their resting state
and stop altering the charge across
their membrane. The neurotransmitters are either broken down or reabsorbed by the axon terminal
1596
The three types of structures in each sensory system are:
accessory structures
receptor cells
output neurones
1597
Receptor cells are ___ cells with a "standing current flow" through them even when they are ___ stimuli.
Generally receptor cells are ___ polarized than ___, and stimuli ___ receptors' ion channels and alter the flow of current compared to the ___.
1. leaky
2. absent
3. less
4. neurons
5. modulate
6. flow at rest
1598
The intermediate layer of the eye is the ___; it is a ___ layer that continues to form a lumpy structure called the ___. This is composed of muscles, processes and ligaments arranged in a ring, from which are attached the ___, around the ___.
1. choroid
2. vascular
3. ciliary body
4. muscles of the iris
5. lens
1599
Where is the transmitter that relays cells located in the eye?
the end of the inner segment
1600
what are the correct functions of a putative "where and where to?" information stream.
Detecting motion
| Detecting changing stimuli
1601
What is the test that relates to working memory?
letter-span
1602
Where is working memory predominantly located?
the frontal and parietal lobes
1603
What are the main 4 symptoms of PD?
tremor
impaired balance
slowness of movement
stiffness of limbs
1604
People with PD lose neurons in a ___ brain structure called the locus coeruleus of the pons. This is the main area where a chemical called ___ is made, in addition to having a key role in our ___ responses.
1. lower
2. noradrenaline
3. stress and pain
1605
```
Excitatory neurons make neurotransmitters that
open ion channels that ___
the dendrite’s membrane; inhibitory
neurons make neurotransmitters that
___ it.
```
1. depolarize
| 2. hyperpolarize
1606
The brain’s most common excitatory neurotransmitter
is ___; the brain’s most common inhibitory
neurotransmitter is ___.
1. glutamate
| 2. gamma-aminobutyric acid (GABA)
1607
What ionotropic receptors can glutamate bind to? How fast are they?
AMPA receptors is fast and brief
| NMDA receptors activate more slowly
1608
Ionotropic GABA receptors have ion channels that let
___ enter the cell. Metabotropic GABA receptors open ion channels that ___. In both instances, ion movement pushes membrane potential downward and ___ a neuron from ___.
1. negatively charged chloride ions
2. release potassium ions
3. inhibits
4. firing
1609
If the receptor is on the surface of the cell, the bound molecule changes the receptor’s ___ across the ___ and starts a chain of ___. This signal transduction pathway ultimately modifies ___, either by shifting the cell’s ___ or by changing the activity of specific enzymes.
1. shape
2. cell membrane
3. intracellular reactions
4. neuronal function
5. ion balance
1610
If a molecule can diffuse through the cell membrane its receptor might be a ___ inside the ___. When the hormone binds to its ___, the complex can transform into a ___ factor that is capable of entering the ___, binding to specific ___ and changing their activity.
1. protein
2. neuron’s soma
3. receptor
4. transcription
5. cell nucleus
6. genes
1611
Sensory systems do what?
translate the different types of energy and molecules you are surrounded by into perceptions or sensations
1612
The lens can ___ to bring near or far objects into ___ on the ___.
1. thicken or flatten
2. better focus
3. retina
1613
The retina consists of what 3 types of neurons?
photoreceptors
interneurons
ganglion cells
1614
Rods and cone are located in the most ___ layer of the retina. This means that after entering through the ___, light travels through the ___ before it reaches the photoreceptors.
1. peripheral
2. cornea and lens
3. ganglion cells and interneurons
1615
what do the axons of ganglion cells exit the retina as?
the optic nerve
1616
Rods, which make up about ___ of photoreceptors
| in humans, are extremely ___, allowing you to see in ___.
1. 95%
2. sensitive
3. dim light
1617
Cones pick up ___, allowing you to engage in
| activities that require a great deal of ___.
1. fine detail and color
| 2. visual acuity
1618
How many types of cones are in the human eye?
3
1619
What is the area immediately around the fovea called?
the macula
1620
what photoreceptors are in the fovea?
red/green cones
1621
Why is vision is sharper in the fovea than in the periphery?
the center of the retina contains many more cones than other
retinal areas
1622
The portion of visual of space providing input to a single ganglion cell:
a receptive field
1623
If light strikes the entire receptive field evenly (both centre and surround), the ganglion cell responds:
weakly
1624
The center-surround ___ of RGCs is the first way our visual system maximizes the perception of ___, which is key to ___.
1. antagonism
2. contrast
3. object detection
1625
Neural activity in the axons of ganglion cells is ___ via the optic nerves, which exit the ___ and travel toward the back of the brain. Because there are no ___ at this site, the exit point of the optic nerve results in a small ___ in each eye, which our brains fortuitously ___ using information from the ___.
1. transmitted
2. back of each eye
3. photoreceptors
4. “blind spot”
5. “fill in”
6. other eye
1626
What is the primary visual cortex?
A thin sheet of neural tissue, located in the occipital lobe at the back of your brain.
1627
The middle layer of the cortex does what?
receives messages from the thalamus, and has receptive fields similar to those in the retina and can preserve the retina’s visual map.
1628
Cells above and below the middle layer of the visual cortex have more complex ___, and they register stimuli shaped like ___ or with particular ___.
1. receptive fields
2. bars or edge
3. orientations
1629
As visual information from the primary visual cortex is combined in other areas, receptive fields become: ___
Some neurons at higher levels of processing, for example, respond: ___
1. increasingly complex and selective.
| 2. only to specific objects and faces.
1630
Two visual information streams are the ___ (___ steam), which
heads up toward the ___, and the ___ (___ stream), which heads down to ___.
1. dorsal stream
2. what?
3. parietal lobe
4. ventral stream
5. where/where to?
6. the temporal lobe
1631
What does binocular vision allow you to perceive?
depth
1632
What qualities of sound can we perceive?
pitch
loudness
duration
location
1633
Rows of small sensory hair cells
| are located on top of the:
vibrating basilar membrane
1634
what is the basilar membrane?
An elastic membrane, that runs along the inside of the cochlea like a winding ramp, spiraling from the outer coil, near the oval window, to the innermost coil.
1635
Microscopic hair-like ___ extending from the hair cells bend against an overlying structure called the ___. This bending opens small channels in the stereocilia that allow ___ in the surrounding fluid to rush in, converting the physical movement into an ___.
1. stereocilia
2. tectorial membrane
3. ions
4. electrochemical signal
1636
Hair cells stimulated in this way then excite the ___, which sends its electrical signals on to the ___. The next stop for sound processing is the ___, the brain’s relay station for incoming sensory information, which then sends the information into the auditory part of the ___.
1. auditory nerve
2. brainstem
3. thalamus
4. cerebral cortex
1637
On the way to the cortex, the brainstem and thalamus use
| the information from both ears to compute a sound’s:
direction and location
1638
Where is the primary auditory cortex?
In the temporal lobe
1639
Different auditory neurons respond to different ___. Some cortical neurons, however, respond to sound qualities such as ___. Other neurons are selective for ___, while still others specialize in various combinations of tones.
1. frequencies
2. intensity, duration, or a change in frequency
3. complex sounds
1640
Signals from touch receptors travel along ___ that connect to neurons in the ___. From there, the signals move upward to the ___ and on to the ___, where they are translated into a touch perception.
1. sensory nerve fibers
2. spinal cord
3. thalamus
4. somatosensory cortex
1641
In touch, acuity is greatest (and the two-point threshold is lowest) in the:
most densely nerve-packed areas of the body, like the fingers
and lips.
1642
nociceptors respond only to:
strong or high-threshold stimuli.
1643
Pain and itch information is sent to the spinal cord via:
A-delta and C class nerve fibres
1644
The Myelin sheath covering A-delta fibers helps nerve impulses travel ___, and these fibers evoke the ___ produced, for example, by a pinprick.
1. faster
| 2. immediate, sharp, and easily identified pain
1645
The unmyelinated C fibers transmit pain messages more ___; their nerve endings spread over a relatively large area and produce a ___ whose origin is ___ to pinpoint.
1. slowly
2. dull and diffuse ache or pain sensation
3. harder
1646
How are pain and itch sensations sent to the cerebral cortex?
through the spinal cord, brainstem, then thalamus.
1647
Why do you often not experience pain in stressful situations?
Because adrenalin is released, which relieves and reduces pain by intercepting the pain signals ascending in the
spinal cord and brainstem.
1648
what motor neurons controls skeletal muscles?
alpha motor neurons
1649
What discovery was made from the study of Henry Molaison?
That the roles of the hippocampus and
parahippocampal region is converting
memories from short-term to long-term memories.
1650
Thanks in part to H.M., scientists now know that the ___, which includes the hippocampus and parahippocampal regions, works with other regions of the ___, the brain’s outermost layer, to ___ memories.
1. medial temporal lobe
2. cerebral cortex
3. form, organize, consolidate, and retrieve
1651
What is declarative memory?
memory for facts, data, and events.
1652
What does the amygdala do?
mediates emotional significance of memories and modulates fight or flight responses.
1653
Some aspects of working memory are coordinated by the ___, the “brain’s executive,” which also controls ___.
1. prefrontal cortex (PFC)
| 2. attention, decision-making, and long-term planning
1654
Working memory is a ___ of declarative memory
1. temporary type
1655
What is another name for nondeclarative memory?
procedural memory
1656
What type of memory is stored and retrieved without
| conscious effort?
procedural memory
1657
Motor skill learning involves what areas of the brain?
the basal ganglia — the “habit center” of the brain — the prefrontal cortex, and the cerebellum, an area at the back of the brain involved in motor control and coordination.
1658
Synaptic plasticity:
The ability of synapses to remodel themselves
1659
Encoding a new long-term memory involves:
persistent changes in the number and shape of synapses, as
| well as the amount of neurotransmitter released and the number of receptors on the postsynaptic membrane
1660
What are receptors?
proteins that interact with neurotransmitters.
1661
LTP:
is a long-lasting increase in synaptic strength, which occurs in many brain regions but especially in the hippocampus
1662
LTD:
decreases a synapse’s effectiveness.
1663
Where does LTP particularly occur?
In the hippocampus
1664
What classes of receptors are ion channels that bind to glutamate?
AMPA
| NMDA
1665
.Upon binding glutamate, NMDA and AMPA receptors permit ___ ions, respectively, to flow ___ the cell. Increasing the number of receptors on the ___ cell ___ a synapse by allowing the entry of more electrically conductive ions.
1. calcium and sodium
2. into
3. postsynaptic
4. strengthens
1666
Calcium ions also function as second messengers by:
Signaling molecules that set off a chain of molecular events
within cells.
1667
LTP boosts the concentration of ___ inside a postsynaptic cell, while LTD increases it to a ___ degree.
1. calcium ions
| 2. lesser
1668
The different concentrations of calcium activate different enzymes that:
modify the synapse, making it more or
| less efficient at relaying nerve impulses
1669
In LTP, a series of molecular events stabilizes the ___ changes: The ___ in calcium ions within the postsynaptic cell activates ___. This, in turn, activates several kinds of ___, some of which ___ the number of synaptic ___, making the synapse more sensitive to ___.
1. synaptic
2. increase
3. cAMP molecules
4. enzymes
5. increase
6. receptors
7. neurotransmitters
1670
What do neurotrophins do?
stimulate the growth of the synapse and structural elements, stabilizing increased sensitivity to neurotransmitters
1671
What type of learning is emotional learning?
nondeclarative
1672
What part of the brain is conditioning associated with?
the amygdala
1673
hen something is very rewarding, we are more likely to remember it. That is because:
dopamine influences the synapses in the entire reward pathway — the hippocampus, amygdala, and the
prefrontal cortex — to create emotional associations with rewards.
1674
```
the longer a person stays awake, the
more ___ they will experience
during the SWS state. Slow waves
become ___ frequent the longer the
person is asleep.
```
1. slow waves
| 2. less
1675
```
Brain activity recorded during REM
looks very similar to EEGs recorded
___. EEG waves during REM
sleep have much ___ amplitudes
than the SWS slow waves, because
neuron activity is ___.
```
1. while awake
2. lower
3. less synchronized
1676
In what stage of sleep is brain activity must synchronized?
slow wave sleep
1677
Atonia, which happens in REM sleep is:
| The only muscles not paralyzed are:
a loss of muscle tone causing the body to become temporarily paralyzed.
those for breathing and eye movements.
1678
```
During the night, periods of
SWS and REM sleep alternate in
___-minute cycles with ___ minutes
of SWS followed by ___
of REM sleep.
```
1. 90
2. 75–80
3. 10–15 minutes
1679
Neurons connecting with the forebrain use the
| neurotransmitters ___ to keep us awake.
1. acetylcholine, norepinephrine, serotonin, and glutamate
1680
During SWS, the brain systems that keep us ___ are actively suppressed. This active suppression of arousal systems is caused by the ___.
1. awake
| 2. ventrolateral preoptic (VLPO) nuclei
1681
What is the VLPO?
a group of nerve cells in the hypothalamus
1682
.Cells in the VLPO release the ___ neurotransmitters galanin and___, which can suppress the ___.
1. inhibitory
2. gamma-aminobutyric acid (GABA)
3. arousal systems
1683
What two main factors drive your body
| to crave sleep?
the time of day or night (circadian system) and how long you
have been awake (homeostatic system).
1684
When you stay awake for a long time, adenosine levels in the
brain ___. The adenosine binds to specific receptors on ___ in ___ to slow cellular activity and ___ arousal. Adenosine can ___ the number of slow waves during SWS. As you get more sleep, ___ levels fall and slow waves decrease in number.
1. increase
2. nerve cells
3. arousal centers
4. reduce
5. increase
6. adenosine
1685
What are the internal and external inputs for arousal?
Neurotransmitters
| Sensory input
1686
The brain is part of many homeostatic systems, providing signals that coordinate your body’s ___ and regulating ___ secretion by the ___. These functions often involve a region of the forebrain called the ___.
1. internal clocks
2. hormone
3. endocrine system
4. hypothalamus
1687
Researchers first identified clock genes in which animal?
the fruit fly
1688
Neurons in the SCN act like a metronome for the rest of the body- they:
emit a steady stream of action potentials
| during the day and become quiet at night.
1689
Neurons in the SCN stimulate an adjacent region of the brain called the ___, which in turn sends signals down a chain of neurons through the ___ to the peripheral organs of the body
1. paraventricular nucleus (PVN)
| 2. spinal cord
1690
Coordinated body clocks enable your body’s ___ to work together at the ___.
1. physiological systems
| 2. right times
1691
Neurons can ___ deliver the brain’s messages to ___ targets in the body. Hormones, on the other hand, deliver
messages more ___ but can affect a ___ of tissues, producing large scale changes in ___.
1. quickly
2. precise
3. slowly
4. larger set
5. metabolism, growth, and behavior.
1692
The brain regions involved in hormone release are called
| the:
neuroendocrine system.
1693
The hypothalamus oversees the production and release of many ___ through its close ties to the ___.
1. hormones
| 2. pituitary gland
1694
Scientists believe that many, if not all, neurodegenerative diseases may involve misfolded proteins called:
prions
1695
In AD, over time, a person’s brain undergoes irreversible, progressive ___ that impairs their ___.
1. degeneration
| 2. memory and reasoning
1696
In AD, damage to ___ impairs attention, memory,
| learning, and higher cognitive abilities
neuronal transport
1697
What is amyloid-beta 42 formed from?
malformed clumps of a fragment of amyloid precursor protein (APP)- a fibrous protein often found at neuronal synapses
1698
Amyloid-beta 42 accumulations first appear where?
in the neocortex
1699
What does the TREM2 protein usually do?
helps regulate removal of cell debris, clearing amyloid proteins, and supressing inflammation in microglia.
1700
In PD, Lewy bodies are mainly composed of the protein
| ___ entangled with other proteins.
alpha-synuclein
1701
The Lewy body protein, alpha-synuclein, is involved in:
dopamine transport in the nervous system.
1702
What is HD?
a heritable disease that impairs voluntary movement and cognition.
1703
In HD, The greater the number of CAG repeats:
the earlier symptoms appear and the more severe they are.
1704
In HD, what brain areas are most affected?
the basal ganglia (voluntary movement) and the cortex (cognition, perception, and memory).
1705
What are the 2 functions of the spinal cord?
it controls reflexes ,and it forms a highway between the body and the brain for information travelling in both directions
1706
Interneurons:
mediate simple reflexes as well
as being responsible for the highest functions of
the brain
1707
The thalamus:
relays impulses from all sensory systems to the cerebral
| cortex, which in turn sends messages back to the thalamus.
1708
The thalamus:
relays impulses from all sensory systems to the cerebral
| cortex, which in turn sends messages back to the thalamus.
1709
what is the core of the cerebral hemispheres?
| What does it have a key role in?
the basal ganglia
| initiation and control of movement
1710
What is the most highly developed area in the brain in humans?
the cerebral cortex
1711
The pathways from the sensory receptors to the cortex and
| from cortex to the muscles:
cross over from one side to the other.
1712
Sounds in the left ear go to the:
right side of the auditory cortex
1713
Neurons both ___ with each other in regulating the overall state of the nervous system
cooperate and compete
1714
the dendrite ___, the cell-body ___ and the axons ___ - a concept called ___ because the information they process supposedly goes in only one direction
1. receives
2. integrates
3. transmit
4. polarization
1715
What are growth factors?
| What do they allow?
Factors that influence the expression of neuronal genes and hence the manufacture of new proteins. These enable the neuron to grow longer dendrites or make yet other dynamic changes to its shape or function.
1716
What is synaptic transmission?
Communication between nerve cells at synapses
1717
The electrical currents in neurons can are usually currents
that come into the cell, called ___, or they may be
currents that move out of the cell, called ___.
1. excitation
| 2. inhibition
1718
When an action potential starts at the cell body, the first
channels to open are ___. A pulse of ___ flashes into the cell and a new equilibrium is established within a millisecond. In a trice, the transmembrane voltage switches by about ___. It flips from an inside membrane voltage that is negative (about -70 mV) to one that is positive (about ___). This switch opens ___, triggering a pulse of ___ to flow out of the cell, and this in turn causes the ___ to swing back again to its original negative value on the inside.
1. Na+ channels
2. sodium ions
3. 100 mV
4. +30 mV
5. K+ channels
6. potassium ions
7. membrane potential
1719
Ions are kept in balance by ___ whose job is to bale out excess ___.
1. ion pumps
| 2. sodium ions
1720
The arrival of an action potential at the presynaptic terminals leads to the opening of ion-channels that let in ___. This activates ___ that act on a range of ___, which race around tagging and trapping others, causing the releasable ___ to fuse with the membrane, burst open, and release the ___ out of the nerve ending.
1. calcium (Ca++)
2. enzymes
3. presynaptic proteins
4. synaptic vesicles
5. chemical messenger
1721
At inhibitory synapses, activation of ___ leads to the opening of ___ that allow the ___ of negatively charged ions giving rise to a change in membrane potential called. This opposes membrane ___ and therefore the initiation of an action potential at the cell body of the receiving neuron. There are two inhibitory neurotransmitters – ___
1. receptors
2. ion channels
3. inflow
4, an inhibitory post-synaptic potential
5. depolarisation
6. GABA and glycine
1722
Ionotropic receptors have a channel through which ions pass (such as ___). Metabotropic receptors do not have channels, but are coupled to ___ inside the cell-membrane that can pass on ___.
1. Na+ and K+
2. G-proteins
3. the message
1723
How long does it take for a message to pass between two neurons?
1 millisecond
1724
What type of receptors do not lead to the initiation of APs and instead do neuromodulation?
metabotropic receptors
1725
What are the bridging molecules on metabotropic receptors called?
G proteins
1726
The effects of neuromodulation include:
changes in ion channels, receptors, transporters and even the expression of genes.
1727
Among the many messengers acting on G-protein coupled
| receptors are:
acetylcholine, dopamine and noradrenalin
1728
Noradrenaline is released in response to:
various forms of novelty and stress
1729
Dopamine is responsible for:
rewarding for the animal, by acting on brain centres associated with positive emotional features
1730
What mechanoreceptors respond to vibration and flutter?
Meissner's corpuscle and Pacinian corpuscle
1731
What type of mechanoreceptor respond to a sustained indentation of the skin (pressure)?
Merkel's disk
1732
What mechanoreceptor responds to slowly changing indentatins?
Ruffini endings
1733
What is the RF of a mechanoreceptor?
the area of skin over which
| each individual receptor responds.
1734
Pacinian corpuscles have much ___ receptive fields than Meissner’s corpuscles
1. larger
1735
In touch, cross-talk between sensory and motor systems begins where?
at the first relays in the spinal cord
1736
Action potentials in the nociceptive nerves entering the
___ initiate automatic protective reflexes, such as
the ___.
1. spinal cord
| 2. withdrawal reflex
1737
In hyperalgesia:
There is a lowering of the pain threshold, an
increase in the intensity of pain, and sometimes both a
broadening of the area over which pain is felt or even pain in
the absence of noxious stimulation.
1738
The more common photoreceptor, ___, are about ____ times more sensitive to light than ___.
1. rods
2. 1000
3. cones
1739
Optic nerves cross over at the ___, forming bundles of fibres called ___ that project to the ___, then to the ___.
1. optic chiasm
2. optic tracts
3. LGN
4. cerebral cortex
1740
In V1, the ___ stage of cortical processing, the neurons respond best to lines or edges in a ___.
1. first
| 2. particular orientation
1741
Decision-making of the sensory cortex involves:
sensory input and existing knowledge
1742
What is another name for V5 of the visual cortex?
MT
1743
Motion-detecting neurons are found where in the visual cortex?
Stimuli must be what for them to respond?
1. MT/V5
| 2. in the right direction
