Chapter 2 - Functional Neuroanatomy Flashcards
1
Q
Phrenology
A
studying the shape of the head
2
Q
Gross neuroanatomy
A
features of the nervous system visible to the naked
3
Q
central nervous system (CNS
A
consists of the brain and spinal cord.
4
Q
peripheral nervous system
A
all parts of the nervous system found outside the skull and spinal column
5
Q
peripheral nervous system three components:
A
The peripheral nervous system consists of nerves, or bundles of axons, and has three components: 1. Cranial nerves–connected to the brain 2. Spinal nerves–also called somatic nerves, connected to the spinal cord 3. Autonomic nervous system–primarily controls glands and internal organs
6
Q
Spinal nerves or somatic nerves two distinct branches, or roots:
A
Spinal nerves or somatic nerves–31 pairs Each spinal nerve is the fusion of two distinct branches, or roots: 1. Dorsal (back) root–carries sensory information from the body to the spinal cord 2. Ventral (front) root–carries motor information from the spinal cord to the muscles
7
Q
Preganglionic neurons
A
run from the CNS to the autonomic ganglia.
8
Q
Postganglionic neurons
A
run from the autonomic ganglia to targets in the body.
9
Q
autonomic ganglia
A
A Group of neurons that are located outside the CNS.
10
Q
The autonomic nervous system And the three major divisions:
A
spans the central and peripheral nervous systems. The autonomic nervous system has three major divisions: 1. Sympathetic nervous system 2. Parasympathetic nervous system 3. Enteric nervous system
11
Q
Neurons
A
or nerve cells, are the most important part of the nervous system
12
Q
Glial cells
A
provide support for neurons.
13
Q
Neuron doctrine
A
states that: The brain is composed of independent cells. Information is transmitted from cell to cell across synapses.
14
Q
A neuron has four zones
A
- Input zone–receives information from other cells through dendrites 2. Integration zone–cell body (or soma) region where inputs are combined and transformed 3. Conduction zone–single axon leads away from the cell body and transmits the electrical impulse 4. Output zone–axon terminals at the end of the axon communicate activity to other cells
15
Q
Functions of Neurons
A
- Motoneurons (motor neurons) stimulate muscles or glands. 2. Sensory neurons respond to environmental stimuli, such as light, odor, or touch. 3. Interneurons receive input from and send input to other neurons
16
Q
Glial Cells Four types
A
Glial cells support neuronal activity 1. Astrocytes–star-shaped cells with many processes that receive neuronal input and monitor activity 2. Microglial cells, or microglia–small cells that remove debris from injured cells 3. Oligodendrocytes are glial cells that form myelin sheath in the brain and spinal cord. 4. Schwann cells provide myelin to cells outside the brain and spinal cord. Glial cells respond to injury by edema, or swelling, and are also susceptible to tumors.
17
Q
Myelination
A
Myelination–the process in which glial cells wrap axons with a fatty sheath, myelin, to insulate and speed conduction
18
Q
Nodes of Ranvier
A
gaps between sections of myelin where the axon is exposed
19
Q
Multiple sclerosis
A
a demyelinating disease
20
Q
Synapses three components
A
Synapses have three components: 1. Presynaptic membrane–on the axon terminal of the presynaptic neuron 2. Postsynaptic membrane–on the dendrite or cell body of the postsynaptic neuron 3. Synaptic cleft–a gap that separates the membranes
21
Q
Golgi stains
A
fill the whole cell, including details, but only stain a small proportion of neurons. Fluorescent molecule injections give a similar result.
22
Q
Nissl stains
A
outline all cell bodies because the dyes are attracted to RNA, which encircles the nucleus.
23
Q
glial cells
A
Also called glia or neuroglia. Nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain. Glial cells are of clinical interest for several reasons. Unlike neurons, glial cells continue to divide throughout life, and consequently they form many of the types of tumors that arise in the brain. Some glial cells, especially astrocytes, respond to brain injury by changing in size—that is, by swelling.
24
Q
neuron doctrine
A
The hypothesis that the brain is composed of separate cells that are distinct structurally, metabolically, and functionally. 1) the brain is composed of separate neurons and other cells that are independent structurally, metabolically, and functionally; and (2) Information is transmitted from cell to cell across tiny gaps.
25
neuron or nerve cell
The basic unit of the nervous system, each composed of a cell body, receptive extension(s) (dendrites), and a transmitting extension (axon).
26
synapse
The tiny gap between neurons where information is passed from one to the other.
27
mitochondrion
A cellular organelle that provides metabolic energy for the cell’s processes
28
cell nucleus
The spherical central structure of a cell that contains the chromosomes
29
ribosomes
Structures in the cell body where genetic information is translated to produce proteins
30
axon
A single extension from the nerve cell that carries nerve impulses from the cell body to other neurons. The axon has two quite different functions: rapid transmission of electrical signals along the outside of the axon, and the much slower transportation of substances inside the axon, to and from the axon terminals.
31
dendrite
One of the extensions of the cell body that are the receptive surfaces of the neuron.
32
input zone
The part of a neuron that receives information, from other neurons or from specialized sensory structures. Usually corresponds to the cell’s dendrites.
33
cell body or soma
The region of a neuron that is defined by the presence of the cell nucleus.
34
integration zone
The part of the neuron that initiates nerve electrical activity, described in detail in Chapter 3. Usually corresponds to the neuron’s axon hillock
35
conduction zone
The part of the neuron over which the nerve’s electrical signal may be actively propagated. Usually corresponds to the cell’s axon.
36
axon terminal
Also called synaptic bouton. The end of an axon or axon collateral, which forms a synapse on a neuron or other target cell.
37
output zone
The part of a neuron, usually corresponding to the axon terminals, at which the cell sends information to another cell.
38
multipolar neuron
A nerve cell that has many dendrites and a single axon
39
bipolar neuron
A nerve cell that has a single dendrite at one end and a single axon at the other end
40
unipolar neuron
Also called monopolar neuron. A nerve cell with a single branch that leaves the cell body and then extends in two directions; one end is the receptive pole, the other end the output zone.
41
motoneuron
Also called motor neuron. A nerve cell that transmits motor messages, stimulating a muscle or gland.
42
sensory neuron
A neuron that is directly affected by changes in the environment, such as light, odor, or touch.
43
interneuron
A neuron that is neither a sensory neuron nor a motoneuron; it receives input from and sends output to other neurons.
44
arborization
The elaborate branching of the dendrites of some neurons.
45
presynaptic
Referring to the region of the synapse that releases neurotransmitter.
46
presynaptic membrane
Referring to the region of a synapse that receives and responds to neurotransmitter
47
postsynaptic membrane
The specialized membrane on the surface of the cell that receives information by responding to neurotransmitter from a presynaptic neuron.
48
neural plasticity
Also called neuroplasticity. The ability of the nervous system to change in response to experience or the environment. Studding the dendrites of many neurons are outgrowths called dendritic spines that, by effectively increasing the surface area of the dendrites, allow for extra synaptic contacts. Both the number and structure of dendritic spines may be rapidly altered by experience, such as training or exposure to sensory stimuli
49
synaptic cleft
The space between the presynaptic and postsynaptic elements.
50
synaptic vesicle
A small, spherical structure that contains molecules of neurotransmitter.
51
neurotransmitter
Also called synaptic transmitter, chemical transmitter, or simply transmitter. The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons.
52
receptor
Also called receptor molecule. A protein that binds and reacts to molecules of a neurotransmitter or hormone.
53
astrocyte
A star-shaped glial cell with numerous processes (extensions) that run in all directions. Astrocytes receive synapses directly from neurons and also surround and monitor the activity of nearby neuronal synapses. They may then communicate among themselves and with the neighboring neurons to modulate the neurons’ responses
54
microglial cells
Also called microglia. Extremely small glial cells that remove cellular debris from injured or dead cells. But we are beginning to realize that microglial cells are involved in more than just damage control: for example, microglial cells appear to be a key component of neural pain systems They are also important for the maintenance of synapses; interference with this function is associated with the development of Alzheimer’s and other dementias
55
axon hillock
A cone-shaped area from which the axon originates out of the cell body. Functionally, the integration zone of the neuron.
56
axon collateral
A branch of an axon from a single neuron.
57
myelination
The process of myelin formation. The process of myelination continues for a long time in humans, 10–15 years after birth, and possibly throughout life.
58
myelin
The fatty insulation around an axon, formed by glial cells, that improves the speed of conduction of nerve impulses. • Purpose of myelin - a large increase in the speed with which electrical signals pass down the axon, jumping from one node to the next • the manner in which glial cells surround some synaptic contacts suggests that one of their roles is to insulate and isolate synapses to prevent one from affecting the other
59
innervate
To provide neural input.
60
edema
The swelling of tissue, especially in the brain, in response to injury. In the brain it is primarily due to glial cells It can damage neurons and is responsible for many symptoms of brain injuries
61
multiple sclerosis
Literally, “many scars”; a disorder characterized by widespread degeneration of myelin. Aka. demyelinating
62
axonal transport
The transportation of materials from the neuronal cell body to distant regions in the dendrites and axons, and from the axon terminals back to the cell body.
63
oligodendrocyte
A type of glial cell that forms myelin in the central nervous system.
64
Schwann cell
The glial cell that forms myelin in the peripheral nervous system.
65
node of Ranvier
A gap between successive segments of the myelin sheath where the axon membrane is exposed.
66
gross neuroanatomy
Anatomical features of the nervous system that are apparent to the naked eye
67
peripheral nervous system
The portion of the nervous system that includes all the nerves and neurons outside the brain and spinal cord
68
cranial nerve
A nerve that is connected directly to the brain. The 12 pairs of cranial nerves—1 left-sided and 1 right-sighted in each pair—serve the sensory and motor systems of the head and neck These nerves pass through small openings in the skull, directly entering or leaving the brain without ever joining the spinal cord.
69
spinal nerve
Also called somatic nerve. A nerve that emerges from the spinal cord. 31 pairs of nerves emerge at regularly spaced intervals through openings in the backbone One member of each pair of spinal nerves serves each side of the body. Each spinal nerve consists of the fusion of two distinct branches, called roots, which are functionally different. The dorsal (back) root and the ventral (front) root.
70
central nervous system (CNS)
The portion of the nervous system that includes the brain and the spinal cord.
71
nerve
A collection of axons bundled together outside the central nervous system.
72
motor nerve
A nerve that conveys neural activity to muscle tissue and causes it to contract.
73
sensory nerve
A nerve that conveys sensory information from the periphery into the central nervous system.
74
autonomic nervous system
The part of the peripheral nervous system that supplies neural connections to glands and to smooth muscles of internal organs. the brain’s main system for controlling the organs of the body.
75
dorsal root
The branch of a spinal nerve, entering the dorsal horn of the spinal cord, that carries sensory information from the peripheral nervous system to the spinal cord
76
ventral root
The branch of a spinal nerve, arising from the ventral horn of the spinal cord, that carries motor messages from the spinal cord to the peripheral nervous system.
77
cervical
Referring to the topmost 8 segments of the spinal cord, in the neck region.
78
autonomic ganglia
Collections of nerve cell bodies, belonging to the autonomic division of the peripheral nervous system, that are found in various locations and innervate the major organs. outside of the CNS
79
thoracic
Referring to the 12 spinal segments below the cervical (neck) portion of the spinal cord, corresponding to the chest.
80
lumbar
Referring to the 5 spinal segments that make up the upper part of the lower.
81
sympathetic nervous system
A component of the autonomic nervous system that arises from the thoracic and lumbar spinal cord. In general, sympathetic activation prepares the body for action: blood pressure increases, the pupils of the eyes widen, and the heart quickens. This set of reactions is sometimes called simply the “fight or flight” response.
82
sympathetic chain
A chain of ganglia that runs along each side of the spinal column; part of the sympathetic nervous system. Parasympathetic ganglia are not collected in a chain as sympathetic ganglia are. Rather, parasympathetic ganglia are dispersed throughout the body, usually positioned near the organs affected.
83
parasympathetic nervous system
A component of the autonomic nervous system that arises from both the cranial nerves and the sacral spinal cord. generally helps the body to relax, recuperate, and prepare for future action, sometimes called the “rest and digest” response.
84
sacral
Referring to the 5 spinal segments that make up the lower part of the lower back.
85
acetylcholine
A neurotransmitter produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain. Which tends to slow down activity.
86
enteric nervous system
An extensive meshlike system of neurons that governs the functioning of the gut. plays a key role in maintaining fluid and nutrient balances in the body Part of the CNS
87
coccygeal
Referring to the lowest spinal vertebra (also known as the tailbone).
88
cerebral cortex
Sometimes called simply cortex. The outer covering of the cerebral hemispheres that consists largely of nerve cell bodies and their branches. The cortex is the seat of complex cognition.
89
preganglionic
Literally, “before the ganglion.” Referring to neurons in the autonomic nervous system that run from the central nervous system to the autonomic ganglia.
90
postganglionic
Literally, “after the ganglion.” Referring to neurons in the autonomic nervous system that run from the autonomic ganglia to various targets in the body.
91
frontal lobe
The most anterior portion of the cerebral cortex. important for movement and high-level cognition
92
parietal lobes
Large regions of cortex lying between the frontal and occipital lobes of each cerebral hemisphere. receive sensory information from the body and participate in spatial cognition.
93
temporal lobes
Large regions of coLarge lateral cortical regions of each cerebral hemisphere, continuous with the parietal lobes posteriorly, and separated from the frontal lobe by the Sylvian fissure Auditory information damage here can impair hearing the temporal lobes are also particularly associated with the sense of smell, and with aspects of learning and memory rtex covering much of the posterior part of each cerebral hemisphere.
religiosity
94
occipital lobes
Large regions of cortex covering much of the posterior part of each cerebral hemisphere. receive and process information from the eyes, giving rise to the sense of vision.
95
norepinephrine
Also called noradrenaline. A neurotransmitter produced and released by sympathetic postganglionic neurons to accelerate organ activity. Also produced in the brainstem and found in projections throughout the brain.
96
cerebral hemispheres
The right and left halves of the forebrain.
97
postcentral gyrus
The strip of parietal cortex, just behind the central sulcus, that receives somatosensory information from the entire body. contains a sensory map of the body The sense of touch
binding problem
98
precentral gyrus
The strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control. the precentral gyrus contains an orderly map of the muscles of the body
99
gyrus
A ridged or raised portion of a convoluted brain surface.
100
white matter
A shiny layer underneath the cortex that consists largely of axons with white myelin sheaths. Which consists mostly of fiber tracts. It gains its appearance from the whitish fatty myelin that ensheathes and insulates the axons of many neurons. white matter mostly transmits information.
101
gray matter
Areas of the brain that are dominated by cell bodies and are devoid of myelin. on the exterior is dominated more by nerve cell bodies and dendrites, which are devoid of myelin. A simple view is that gray matter primarily processes information,
102
sulcus
A furrow of a convoluted brain surface.
103
Sylvian fissure aka Latteral fissure
Also called lateral sulcus. A deep fissure that demarcates the temporal lobe.
104
central sulcus
A fissure that divides the frontal lobe from the parietal lobe.
105
corpus callosum
The main band of axons that connects the two cerebral hemispheres.
106
neural tube
An embryonic structure with subdivisions that correspond to the future forebrain, midbrain, and hindbrain.
107
forebrain
Also called prosencephalon. The anterior division of the brain, containing the cerebral hemispheres, the thalamus, and the hypothalamus.
108
midbrain
Also called mesencephalon. The middle division of the brain.
109
cerebellum
A structure located at the back of the brain, dorsal to the pons, that is involved in the central regulation of movement. the surface of the cerebellum is elaborately convoluted, giving it more surface area The cerebellum has long been known to be crucial for motor coordination and control, but we now know it also participates in certain aspects of cognition, including learning.
110
pons
A portion of the metencephalon; part of the brainstem connecting midbrain to medulla. Within the pons are important motor control and sensory nuclei, including several nuclei from which cranial nerves arise.
111
myelencephalon or medulla
The posterior part of the hindbrain, continuous with the spinal cord. The medulla is the most caudal portion of the brainstem, and it marks the transition from brain to spinal cord The reticular formation, stretches through the pons and ends in the medulla. Because the medulla contains nuclei that regulate breathing and heart rate, damage there is often fatal. All axons passing between the brain and spinal cord necessarily course through the medulla
112
hindbrain
Also called rhombencephalon. The rear division of the brain, which, in the mature vertebrate, contains the cerebellum, pons, and medulla.
113
telencephalon
The frontal subdivision of the forebrain that includes the cerebral hemi-spheres when fully developed.
114
diencephalon
The posterior part of the forebrain, including the thalamus and hypo-thalamus.
115
metencephalon
A subdivision of the hindbrain that includes the cerebellum and the pons.
116
brainstem
The region of the brain that consists of the midbrain, the pons, and the medulla.
117
nucleus
Here, a collection of neurons within the central nervous system (e.g., the caudate nucleus).
118
tract
A bundle of axons found within the central nervous system.
119
allocortex
Brain tissue with three layers or unlayered organization.
120
pyramidal cell
A type of large nerve cell that has a roughly pyramid-shaped cell body; found in the cerebral cortex.
121
apical dendrite
The dendrite that extends from a pyramidal cell to the outermost surface of the cortex
122
basal dendrite
One of several dendrites on a pyramidal cell that extend horizontally from the cell body.
123
cortical column
One of the vertical columns that constitute the basic organization of the neocortex.
124
basal ganglia
A group of forebrain nuclei, including caudate nucleus, globus pallidus, and putamen, found deep within the cerebral hemispheres. The basal ganglia are very important in motor control,
125
caudate nucleus
One of the basal ganglia; it has a long extension or tail.
126
putamen
One of the basal ganglia.
127
globus pallidus
One of the basal ganglia.
128
substantia nigra
A brainstem structure in humans that innervates the basal ganglia and is named for its dark pigmentation. Contains neurons that release the transmitter dopamine Loss of this system leads to Parkinson’s disease
129
limbic system
A loosely defined, wide-spread group of brain nuclei that innervate each other to form a network. Curving through each hemisphere, alongside the basal ganglia. It is critical for emotion and learning. Limbic structures near the base of the brain, especially thehypothalamus, help to govern highly motivated behaviors, like sex and aggression, and regulate the hormonal systems of the body..
130
amygdala
A group of nuclei in the medial anterior part of the temporal lobe. (Latin for “almond,” because it has that shape), It has several subdivisions with diverse functions such as emotional regulation and odor perception
131
hippocampus
A medial temporal lobe structure that is important for learning and memory. (from the Greek hippokampos, “sea horse,” which it resembles) .
132
fornix
A fiber tract that extends from the hippocampus to the mammillary body. contribute to learning and memory
133
cingulate gyrus
A cortical portion of the limbic system, found in the frontal and parietal midline Implicated in many cognitive functions, including the direction of attention
134
olfactory bulb
An anterior projection of the brain that terminates in the upper nasal passages and, through small openings in the skull, provides receptors for smell.
135
thalamus
The brain regions that surround the third ventricle. Acts as a switchbox, directing almost all incoming sensory information to the appropriate regions of the cortex for further processing, and receiving instructions back from the cortex to control which sensory information is transmitted.
136
hypothalamus
(which simply means “under thalamus”). Part of the diencephalon, lying ventral to the thalamus. it is packed with discrete nuclei involved in many vital functions, such as hunger, thirst, temperature regulation, sex, and many more. Furthermore, because the hypothalamus also controls the pituitary gland, it serves as the brain’s main interface with the hormonal systems of the body.
137
superior colliculi
Paired gray matter structures of the dorsal midbrain that receive visual information and are involved in direction of visual gaze and visual attention to intended stimuli.
138
inferior colliculi
Paired gray matter structures of the dorsal midbrain that receive auditory information.
139
tectum
The dorsal portion of the midbrain, including the inferior and superior colliculi.
140
red nucleus
A brainstem structure related to motor control. communicates with motoneurons in the spinal cord
141
reticular formation
An extensive region of the brainstem (extending from the medulla through the thalamus) that is involved in arousal (waking). Variety of behaviors, including sleep and arousal, temperature regulation, and motor control.
142
Purkinje cell
A type of large nerve cell in the middle layer of the cerebellar cortex.
143
granule cell
A type of small nerve cell
144
parallel fiber
One of the axons of the granule cells that form the outermost layer of the cerebellar cortex.
145
meninges
The three protective sheets of tissue—dura mater, pia mater, and arachnoid—that surround the brain and spinal cord.
146
dura mater
The outermost of the three meninges that surround the brain and spinal cord.
147
pia mater
the innermost of the three meninges that surround the brain and spinal cord
148
arachnoid
The thin covering (one of the three meninges) of the brain that lies between the dura mater and pia mater. webby (“spiderweb-like”) suspends the brain in a bath of cerebrospinal fluid (CSF).
149
cerebrospinal fluid (CSF)
The fluid that fills the cerebral ventricles.
150
meningitis
An acute inflammation of the meninges, usually caused by a viral or bacterial infection. Potentially lethal medical emergency characterized in early stages by headache, fever, and stiff neck as the inflamed meninges press on the brain.
151
meningiomas
Any of a class of noncancerous tumors arising from the meninges. Usually classified as benign in the sense that they are noncancerous, but of course anything that takes up space within the enclosed cranium may cause trouble.
152
ventricular system
A system of fluid-filled cavities inside the brain.
153
lateral ventricle
A complexly shaped lateral portion of the ventricular system within each hemisphere of the brain.
154
choroid plexus
A highly vascular portion of the lining of the ventricles that secretes cerebrospinal fluid. specialized membrane the lines the lateral ventricles produces CSF by filtering blood
155
third ventricle
The midline ventricle that conducts cerebrospinal fluid from the lateral ventricles to the fourth ventricle.
156
fourth ventricle
The passageway within the pons that receives cerebrospinal fluid from the third ventricle and releases it to surround the brain and spinal cord. It has three small openings allow CSF to exit the ventricular system and circulate over the outer surface of the brain and spinal cord.
157
carotid arteries
The major arteries that ascend the left and right sides of the neck to the brain, supplying blood to the anterior and middle cerebral arteries. It branches into external and internal carotid arteries; these are the major arteries that you can feel pulsing in each side of your neck after exertion. The internal carotid artery enters the skull and branches into anterior and middle cerebral arteries, which supply blood to about two-thirds of the cerebral hemispheres
158
anterior cerebral arteries
Two large arteries, arising from the carotids, that provide blood to the anterior poles and medial surfaces of the cerebral hemispheres.
159
middle cerebral arteries
Two large arteries, arising from the carotids, that provide blood to most of the lateral surfaces of the cerebral hemispheres.
160
posterior cerebral arteries
Two large arteries, arising from the basilar artery, that provide blood to posterior aspects of the cerebral hemispheres, cerebellum, and brainstem.
161
vertebral arteries
Arteries that ascend the vertebrae, enter the base of the skull, and join together to form the basilar artery.
162
basilar artery
An artery, formed by the fusion of the vertebral arteries, that supplies blood to the brainstem and to the posterior cerebral arteries.
163
circle of Willis
A structure at the base of the brain that is formed by the joining of the carotid and basilar arteries.
164
stroke
Damage to a region of brain tissue that results from blockage or rupture of vessels that supply blood to that region. causing the affected region to stop functioning or die.
165
blood-brain barrier
The mechanisms that make the movement of substances from blood vessels into brain cells more difficult than exchanges in other body organs, thus affording the brain greater protection from exposure to some substances found in the blood. It may have evolved to help protect the brain from infections and blood-borne toxins, but it also makes the delivery of drugs to the brain more difficult. Pathological processes that break down the barrier may be important in disease processes like multiple sclerosis, Alzheimer’s disease, and stroke, because antibodies and other blood proteins may improperly enter the brain to cause or worsen damage to neurons
166
angiography
A brain-imaging technique in which a specialized X-ray image of the head is taken shortly after the cerebral blood vessels have been filled with a radiopaque dye by means of a catheter. aids in the diagnosis of vascular disease.
167
computerized axial tomography (CAT or CT)
A noninvasive technique for examining brain structure in humans through computer analysis of X-ray absorption at several positions around the head. When this process is repeated from many angles and the results are mathematically combined, an anatomical map of the brain based on tissue density can be generated by computer. CT scans are medium-resolution images, useful for visualizing problems such as strokes, tumors, or cortical atrophy.
168
magnetic resonance imaging (MRI)
A noninvasive technique that uses magnetic energy to generate images that reveal some structural details in the living brain. It provides higher-resolution images than CT, and because MRI images are derived from radio frequency energy, an additional benefit is that patients are not exposed to potentially damaging X-rays. the patient’s head is placed in the center of an extremely powerful circular magnet that causes all the protons in the brain’s tissues to line up in parallel, instead of in their usual random orientations. the protons are knocked over by a strong pulse of radio waves. When this pulse is turned off, the protons relax back to their original configuration, emitting radio waves as they go. a powerful computer uses this density-based information to generate a detailed cross-sectional map of the brain With their higher resolution, MRI images can reveal subtle changes in the brain, such as the loss of myelin that is characteristic of multiple sclerosis
169
positron emission tomography (PET)
A technique for examining brain function by combining tomography with injections of radioactive substances used by the brain. the objective is to obtain images of the brain’s activity rather than details of its structure, and it has proven to be very valuable for both experimental and medical purposes. Through precise experimental control and the use of special mathematical techniques we can generate metabolic maps of the brain that identify the regions that contribute to specific functions.
170
functional MRI (fMRI)
Magnetic resonance imaging that detects changes in blood flow and therefore identifies regions of the brain that are particularly active during a given task. introduction in the 1990s has revolutionized cognitive neuroscience research, producing images with reasonable speed and excellent sharpness uses high-powered, rapidly oscillating magnetic-field gradients to detect small changes in brain metabolism, particularly the moment-to-moment use of oxygen scientists can use fMRI data to create computer-generated images that reflect the activity of different parts of the brain while people engage in various experimental tasks The detailed activity maps provided by fMRI reveal how networks of brain structures collaborate on complex cognitive processes. The fMRI image generally reflects synaptic inputs and local processing, rather than the production of neural impulses.
171
diffusion tensor imaging (DTI)
A modified form of MRI imaging in which the diffusion of water in a confined space is exploited to produce images of axonal fiber tracts. thus provides a noninvasive method to map the fine axonal connections between different regions of the living human brain
172
optical imaging
A method for visualizing brain activity in which near-infrared light is passed through the scalp and skull. The relatively low expense and small size of the optical imaging apparatus may allow many more laboratories to use brain imaging in their research.
173
transcranial magnetic stimulation (TMS)
Localized, noninvasive stimulation of cortical neurons through the application of strong magnetic fields. The regions stimulated and resultant behavioral effects can then be carefully tracked and mapped.
174
magnetoencephalography (MEG)
A passive and noninvasive functional brain-imaging technique that measures the tiny magnetic fields produced by active neurons, in order to identify regions of the brain that are particularly active during a given task.
175
lesions
Regions of damage within the brain.
176
social neuroscience
The use of neuroscience techniques to understand the neural bases of social processes.
177
dyadic functional MRI (dfMRI)
An fMRI technique in which the brains of two interacting individuals are simultaneously imaged.
178
How much does the brain weigh
Three-pounds or 1400 grams, just 2% of the average body weight. Put your two fists together and you get a sense of the size
179
Why we know more about neurons then glial cells
But because neurons produce readily measured electrical signals and do most of the work of the brain, we know much more about them than about glial cells.
180
Camillo Golgi (1843–1926) Santiago Ramón y Cajal (1852–1934)
• They were able to catalog the astonishing variety of shapes and sizes of neurons in the brain • Golgi, thought that neurons were continuous with one another, forming a nearly endless network of connected tubes through which information flowed. He also invented a revolutionary staining techniques • Cajal developed a convincing alternative. Exploiting Golgi’s staining techniques to create pen-and-ink studies of neurons so precise that they remain accurate and useful to the present day, Cajal proposed that although neurons come very close to one another (i.e., they are contiguous), they are not quite continuous with one another. He insisted that at each point of contact between neurons a tiny gap keeps the cells separate.
181
The Major Parts of the Neuron
1. Cellular extensions called dendrites (from the Greek dendron, “tree”) serve as an input zone, receiving information from other neurons. Dendrites may be elaborately branched to accommodate synapses from many other neurons. 2. A cell body region (or soma, plural somata), which contains the cell’s nucleus, may receive additional synaptic contacts. In most types of neurons, inputs are combined and transformed in the cell body, so it acts as an integration zone. 3. A single extension, the axon, leads away from the cell body and serves as a conduction zone, transmitting the cell’s output information, in the form of electrical impulses, away from the cell body. 4. Specialized swellings at the ends of the axon, the axon terminals (or synaptic boutons), are a functional out
182
Neuroanatomical Methods Provide Ways to Make Sense of the Brain
In the mid-1800s, dyes that were used to color fabrics provided a break-through for microscopic studies of tissue. Preserved nerve cells treated with these dyes suddenly become vivid, and hidden parts become evident. Two traditional cell stains—revolutionary in their day, and still in routine use—have allowed for detailed study of the size, shape, and number of neurons. • Golgi stains • Nissl stains Other methods to create images of cells • Autoradiography • immunocytochemistry (ICC) • in situ hybridization Some research questions are most concerned with connections between brain regions, so methods for labeling axon pathways have also been developed. The traditional way to do this is simply to damage neurons of interest and then look for their degenerating axons. Newer procedures accomplish the same goal by the injection of radioactively labeled amino acids into a collection of cell bodies. These radioactive molecules are taken up by the cell, incorporated into proteins, and transported to the tips of the axons where they are then visualized through autoradiography, described earlier Alternatively, the cells of origin of a particular set of axons can be identified using a tract tracer such as horseradish peroxidase (HRP),
183
Tracing pathways in the nervous system is difficult for several reasons:
(1) axons have an even smaller diameter than cell bodies (2) axons from different sources look alike (3) the brain contains billions of axons (4) fibers with different destinations often travel together over parts of their routes, making it hard to disentangle one set from the rest.
184
Golgi stains
Golgi stains fill the whole cell, including details such as dendritic spines. For reasons that remain a mystery, this technique stains only a small number of cells, each of which stands out in dramatic contrast to adjacent unstained cells, so Golgi staining is useful for identifying the type and shape of cells in a region.
185
Nissl stains
Nissl stains outline all cell bodies because the dyes are attracted to RNA distributed within the cell. Nissl stains allow us to measure cell body size and the density of cells in particular regions
186
autoradiography
a procedure known where the cells are manipulated into taking photographs of themselves. For example, experimenters might bathe thin sections of brain tissue in a solution with a radioactively labeled form of the drug. Time is al-lowed for the radioactive drug to reach its target, and then the brain sections are placed on slides and covered with photographic emulsion. Radioactivity emitted by the labeled drug in the tissue “exposes” the emulsion—like light striking film—producing a collection of fine, dark grains wherever the drug has become selectively concentrated
187
immunocytochemistry (ICC) and immediate early genes (IEGs)
A method for detecting a particular protein in tissues in which an antibody recognizes and binds to the protein and then chemical methods are used to leave a visible reaction product around each antibody. Immediate early genes (IEGs) - A class of genes that show rapid but transient increases in expression in cells that have become activated. c-fos - An immediate early gene commonly used to identify activated neurons.
188
horseradish peroxidase (HRP)
1. Multipolar neurons have many dendrites and a single axon, and they are the most common type of neuron (FIGURE 2.4A). 2. Bipolar neurons have a single dendrite at one end of the cell and a single axon at the other end (FIGURE 2.4B). This type of neuron is especially common in sensory systems, such as vision. 3. Unipolar neurons (also called monopolar) have a single extension (or process), usually thought of as an axon, that branches in two directions after leaving the cell body
189
A synapse typically has three principal components
1. The presynaptic membrane of the axon terminal of the presynaptic neuron 2. A specialized postsynaptic membrane on the surface of the dendrite or cell body of the postsynaptic neuron 3. A synaptic cleft, the gap of about 20–40 nanometers (nm) that separates the presynaptic and postsynaptic membranes
190
Types of glial cells
astrocyte microglial cell oligodendrocytes Schwann cells
191
astrocyte microglial cell oligodendrocytes Schwann cells
(1) the cranial nerves, which are connected directly to the brain; (2) the spinal nerves, which are connected at regular intervals to the spinal cord; (3) the autonomic nervous system, the nerves that primarily control the viscera (internal organs). All three components communicate sensory information to the CNS and transmit commands from the CNS to the body.
192
spinal nerves
Each spinal nerve is named according to the segment of spinal cord to which it is connected: 8 cervical (neck), 12 thoracic (trunk), 5 lumbar (lower back), 5 sacral (pelvic), 1 coccygeal (bottom) So, we refer to the spinal nerve that is connected to the twelfth segment of the thoracic portion of the spinal cord as T12, the nerve connected to the third segment of the sacral portion as S3, and so on. Fibers from different spinal nerves join to form peripheral nerves.
193
The autonomic nervous system has three major divisions:
the sympathetic nervous system, the parasympathetic nervous system the enteric nervous system.
194
Why the sympathetic and parasympathetic divisions tend to act in opposite directions,
Because they use different neurotransmitters. The sympathetic system uses norepinephrine (also known as noradrenaline), which tends to accelerate activity, While the parasympathetic system uses acetylcholine, which tends to slow down activity. For example, the heartbeat is quickened by the activity of sympathetic nerves during exercise, but it is slowed by the parasympathetic system during rest. Sympathetic activation constricts blood vessels, raising blood pressure, while parasympathetic activation relaxes vessel walls; sympathetic activation inhibits digestion, while parasympathetic activation stimulates it.
195
The lumpy convolutions of the paired cerebral hemispheres are the result of elaborate folding together of a thick sheet of brain tissue called the…
cerebral cortex
196
What is the purpose of the folding of the cerebral cortex
It enormously increases the cortical surface area; about two-thirds of the cerebral surface is hidden in the depths of these folds.
197
Wilder Penfield’s experiments with stimulation mapping of the brain
revealed that the precentral gyrus contains an orderly map of the muscles of the body. Similarly, the postcentral gyrus contains a sensory map of the body (Penfield and Rasmussen, 1950).
198
Three Orientations for Viewing the Brain and Body
1. The plane that bisects the body into right and left halves is called the sagittal plane 2. The plane that divides the body into a front (anterior) and a back (posterior) part is called coronal plane or the frontal plane 3. The plane which divides the brain into upper and lower parts, is called the horizontal plane.
199
directional terms for describing the brain and body
Relative to one location, a second location is: • Medial means “toward the middle” • Lateral Means “toward the side.” • ipsilateral if it is on the same side of the body • contralateral if on the opposite side of the body. • superior (above) • inferior (below) • anterior or rostral is the head end • posterior or caudal is the tail end • Proximal means “near the center,” • Distal means “toward the periphery” or “toward the end of a limb.” • Dorsal means “toward or at the back,” this term is also used to refer to the top of the brain of a human, even though the top of the brain is not at the back of the body. • ventral means “toward the belly.” is understood to designate the bottom of the brain We call an axon, tract, or nerve: • afferent if it carries information into a region that we are interested in, • efferent if it carries information away from the region of interest
200
directional terms for describing the brain and body Brain (encephalon) 5 major parts
Forebrain 1. Telencephalon(cerebral hemispheres) Diencephalon 2. Midbrain 3. Mesencephalon Hindbrain 4. Metencephalon 5. Myelencephalon (medulla)
201
Telencephalon Includes:
Cortex Basal ganglia Limbic system
202
Diencephalon Includes:
Thalamus Hypothalamus
203
Mesencephalon Includes:
Midbrain
204
Metencephalon Incudes:
Cerebellum Pons
205
Myelencephalon Includes:
medulla
206
bilaterally symmetrical
One important principle of the vertebrate brain is that each side of the brain controls the opposite side of the body: the right side of the brain controls and receives sensory information from the left side of the body, while the left side of the brain monitors and controls the right side of the body.
207
The neurons of the cerebral cortex are arranged in six distinct layers
in mammals this tissue is sometimes referred to as neocortex or isocortex). Each cortical layer is distinct because it consists of either a band of similar neurons or a particular pattern of dendrites or axons.
208
basal ganglia includes:
In the telencephalon • caudate nucleus, • putamen, • globus pallidus In the Mesencephalon • substantia nigra
209
limbic system include:
• Amygdala • Hippocampus • Fornix • cingulate gyrus • olfactory bulb
210
The midbrain include
tectum • superior colliculi • inferior colliculi substantia nigra red nucleus reticular formation
211
Layers of the meninges
1. Tough outer sheet called the dura mater 2. a webby substance called the arachnoid suspends the brain in a bath of cerebrospinal fluid (CSF). 3. delicate pia mater that adheres tightly to the surface of the brain
212
The CSF circulating through the ventricular system has at least two main functions.
First, it acts mechanically as a shock absorber for the brain: floating in CSF, the brain is protected from sudden movements of the head that would smash it against the inside of the skull. Second, CSF provides a medium for the exchange of materials, including nutrients, between blood vessels and brain tissue.
213
CSF is absorbed back into the circulatory system through:
large veins beneath the top of the skull.
214
How much of the body’s energy does the brain use
20% of the body’s energy at rest
215
the five most common warning signs of a stroke are
the exact effects of a stroke depend on the region of the brain that is affected, but five common warning signs are: sudden numbness or weakness, altered vision, dizziness, severe headache, confusion or difficulty speaking.
216
technological innovations in brain imaging have provided researchers with:
noninvasive tools to supplement traditional studies of brain lesions They also give us insights into processes that previously were completely hidden (coma) providing us with new appreciation of the organization and dynamics of massive neural circuits involved in all forms of mental life.
217
Problems with brain images
the colorful images of brain activity that we see everywhere in the popular media seem unambiguous and easy to label hey suffer from a variety of procedural and experimental limitations brain imaging is subject to what the engineers call a “speed-accuracy trade-off” these technologies do not produce actual images of the brain, but rather computer-generated composites The colors assigned to patterns of activation are arbitrary.
218
Directions in the Vertebrate Nervous System DIAGRAM
219
An Overview of the Nervous System DIAGRAM
220
Three Views of the Brain DIAGRAM
221
The Five Major Divisions of the Brain DIAGRAM
222
Lobes of the telencephalon DIAGRAM
223
Major fissures of the telencephalon DIAGRAM
224
Telencephalon – Limbic System DIAGRAM
225
Telencephalon – Basal Ganglia DIAGRAM
226
The human Diencephalon DIAGRAM
227
The human mesencephalon (midbrain) DIAGRAM
228
Metencephalon DIAGRAM
229
Myelencephalon (Brain Stem to Spinal Cord DIAGRAM
230
The Cranial Nerves DIAGRAM
231
Spinal Nerves DIAGRAM
232
The Spinal Cord DIAGRAM
233
The autonomic nervous system DIAGRAM
234
neuron four zones DIAGRAM
235
Multipolar Neurons, Bipolar Neurons, Unipolar Neurons DIAGRAM
236
Synapses DIAGRAM
237
Wilder Penfield's Brain Stimulation
While she remained conscious, comfortable, and aware of her surroundings, Bev’s skull was opened and the surface of her brain was exposed. Using a tiny electrode, the surgeon stimulated her brain in precise locations, while sensory experiences and behavioral responses were carefully noted. B Bev was undergoing a procedure called cortical electrical-stimulation mapping, developed in the mid–twentieth century by neurosurgeon Wilder Penfield (1891–1976). Penfield had learned that by mapping the locations of specific functions in someone’s brain, it became possible to remove diseased brain tissue without harming neighboring regions involved in crucial behaviors like speech or movement. In Bev’s case, the target was a patch of diseased tissue that was causing Bev to experience frequent seizures. But Penfield and others realized that, beyond its utility as a surgical tool, stimulation mapping offered a way to ask more-profound questions about the organization of the human brain. In fact, Wilder Penfield’s experiments with stimulation mapping of the brain, revealed that the precentral gyrus contains an orderly map of the muscles of the body. Similarly, the postcentral gyrus contains a sensory map of the body.
238
What is an MRI, fMRI or a PET scan? Be able to compare and contrast these two forms of imaging the human brain (you need to read these on your own)
magnetic resonance imaging (MRI) A noninvasive technique that uses magnetic energy to generate images that reveal some structural details in the living brain. MRI images are derived from radio frequency energy, the patient’s head is placed in the center of an extremely powerful circular magnet that causes all the protons in the brain’s tissues to line up in parallel, instead of in their usual random orientations. the protons are knocked over by a strong pulse of radio waves. When this pulse is turned off, the protons relax back to their original configuration, emitting radio waves as they go. a powerful computer uses this density-based information to generate a detailed cross-sectional map of the brain With their higher resolution, MRI images can reveal subtle changes in the brain, such as the loss of myelin that is characteristic of multiple sclerosis positron emission tomography (PET) A technique for examining brain function by combining tomography with injections of radioactive substances used by the brain. the objective is to obtain images of the brain’s activity rather than details of its structure, and it has proven to be very valuable for both experimental and medical purposes. we can generate metabolic maps of the brain that identify the regions that contribute to specific functions. functional MRI (fMRI) Magnetic resonance imaging that detects changes in blood flow and therefore identifies regions of the brain that are particularly active during a given task. has revolutionized cognitive neuroscience research, producing images with reasonable speed and excellent sharpness uses high-powered, rapidly oscillating magnetic-field gradients to detect small changes in brain metabolism, particularly the moment-to-moment use of oxygen scientists can use fMRI data to create computer-generated images that reflect the activity of different parts of the brain while people engage in various experimental tasks The detailed activity maps provided by fMRI reveal how networks of brain structures collaborate on complex cognitive processes. The fMRI image generally reflects synaptic inputs and local processing, rather than the production of neural impulses
239
What is the neuron doctrine?
The hypothesis that the brain is composed of separate cells that are distinct structurally, metabolically, and functionally. 1) the brain is composed of separate neurons and other cells that are independent structurally, metabolically, and functionally; and (2) Information is transmitted from cell to cell across tiny gaps.
240
Be able to label the parts of a neuron on a diagram. Also make sure you can define what each part does. DIAGRAM
The basic unit of the nervous system, each composed of a cell body, receptive extension(s) (dendrites), and a transmitting extension (axon). Dendrite - One of the extensions of the cell body that are the receptive surfaces of the neuron. Cell body or soma - The region of a neuron that is defined by the presence of the cell nucleus. Also contains mitochondrion and ribosomes. Axon hillock A cone-shaped area from which the axon originates out of the cell body. Functionally, the integration zone of the neuron. Axon- A single extension from the nerve cell that carries nerve impulses from the cell body to other neurons. The axon has two quite different functions: rapid transmission of electrical signals along the outside of the axon, and the much slower transportation of substances inside the axon, to and from the axon terminals. Axon terminal - Also called synaptic bouton. The end of an axon or axon collateral, which forms a synapse on a neuron or other target cell.
241
What is the input, integration, conduction and output zone of a neuron?
Input zone - The part of a neuron that receives information, from other neurons or from specialized sensory structures. Usually corresponds to the cell’s dendrites. Integration zone - The part of the neuron that initiates nerve electrical activity. Usually corresponds to the neuron’s axon hillock. Conduction zone - The part of the neuron over which the nerve’s electrical signal may be actively propagated. Usually corresponds to the cell’s axon. Output zone - The part of a neuron, usually corresponding to the axon terminals, at which the cell sends information to another cell.
242
How long can neurons be?
In a griaf – 15 feet In a whale - 30 feet In a human – several feet
243
What are glia cells?
Glial cells support neuronal activity There are 4 types that we need to know for the class. Glial cells respond to injury by edema, or swelling, and are also susceptible to tumors.
244
What does glia mean?
Glue
245
Why would neurons come in different shapes and sizes?
Neurons are remarkably diverse in shape, their forms reflecting their highly specialized functions.
246
If you had a picture of a neuron please speculate about what that neuron might do. For example the neurons in 2.3 – based on their morphology what do you think their main purpose might be? DIAGRAM
247
What is/are the difference(s) between a multipolar, bipolar and unipolar neuron? What does there morphology suggest about their function?
Multipolar neuron - A nerve cell that has many dendrites and a single axon. They are the most common type of neuron. Bipolar neuron - A nerve cell that has a single dendrite at one end and a single axon at the other end. This type of neuron is especially common in sensory systems, such as vision. Unipolar neuron -Also called monopolar neuron. A nerve cell with a single branch that leaves the cell body and then extends in two directions; one end is the receptive pole, the other end the output zone. Such cells transmit touch infor-mation from the body into the spinal cord.
248
What is the difference between a motor, sensory and interneuron?
Motoneuron Also called motor neuron. A nerve cell that transmits motor messages, stimulating a muscle or gland. Sensory neuron A neuron that is directly affected by changes in the environment, such as light, odor, or touch. Interneuron A neuron that is neither a sensory neuron nor a motoneuron; it receives input from and sends output to other neurons. Shortest of the three.
249
What is the difference between an oligodendrocyte and Schwann cell?
Oligodendrocyte - A type of glial cell that forms myelin in the central nervous system. Schwann cell- The glial cell that forms myelin in the peripheral nervous system.
250
Are all axons myelinated?
No Many thin, short axons lack myelin but still are surrounded by oligodendrocytes or Schwann cells, which segregate the unmyelinated axons
251
What is the node of Ranvier? Why is it important?
Node of Ranvier - A gap between successive segments of the myelin sheath where the axon membrane is exposed. It is important because it serves to facilitate the rapid conduction of nerve impulses
252
What are the roles of astrocytes and microglia?
Glial Cells Astrocyte - A star-shaped glial cell with numerous processes (extensions) that run in all directions. Microglial cells Also called microglia. Extremely small glial cells that remove cellular debris from injured or dead cells.
253
What is a dendritic spine/synapse??
Synapse - The tiny gap between neurons where information is passed from one to the other. Studding the dendrites of many neurons are outgrowths called dendritic spines that, by effectively increasing the surface area of the dendrites, allow for extra synaptic contacts. Both the number and structure of dendritic spines may be rapidly altered by experience, such as training or exposure to sensory stimuli
254
How does information go from one neuron to another via the synapse
Information is transmitted from the axon terminal of the presynaptic neuron to the receptive surface of the postsynaptic neuron through the synaptic cleft. The synaptic cleft is the gap of about 20–40 nanometers (nm) that separates the presynaptic and postsynaptic membranes. Presynaptic axon terminals contain numerous tiny spheres, called synaptic vesicles, each 30–140 nm in diameter. Each vesicle contains a specialized chemical substance, a neurotransmitter, which the neuron uses to communicate with postsynaptic neurons. In response to electrical activity in the axon, these vesicles fuse with the presynaptic membrane, releasing molecules of neurotransmitter into the cleft. After crossing the cleft, the released neurotransmitter interacts with postsynaptic receptors: specialized protein molecules that capture and react to molecules of the neurotransmitter.
255
What is/are the difference(s) between the central and peripheral nervous systems?
a natural subdivision into a peripheral nervous system (all nervous system parts that are outside the bony skull and spinal column) and a central nervous system (CNS), consisting of the brain and spinal cord
256
What is/are the general functions of the cranial nerves? be familiar with what they are – for example if I asked you for five areas of the face that the cranial nerves process neural information for you should be able to answer this DIAGRAM
Cranial nerves serve the sensory and motor systems of the head and neck. Three cranial nerves are exclusively sensory pathways to the brain: the olfactory, the optic and the nerve is concerned with hearing and balance. Five nerves are exclusively motor pathways from the brain: three nerve pathways innervate muscles to move the eye; one pathway controls neck muscles; and one controls the tongue. The remaining cranial nerves have both sensory and motor functions. One serves facial sensation and it controls chewing movements through other axons. Another set of nerves control facial muscles and receive taste sensation, there are nerves that receive sensation from the throat and control the muscles there. And the vagus (X) nerve extends far from the head, running to the heart, liver, and intestines. DIAGRAM
257
What is the somatic part of the peripheral nervous system?
Spinal nerves–also called somatic nerves, connected to the spinal cord Each spinal nerve is the fusion of two distinct branches, or roots: 1.Dorsal (back) root–carries sensory information from the body to the spinal cord 2.Ventral (front) root–carries motor information from the spinal cord to the muscles
258
What is the main difference between the ventral and dorsal roots of the spinal cord?
Each spinal nerve is the fusion of two distinct branches, or roots: 1.Dorsal (back) root–carries sensory information from the body to the spinal cord 2.Ventral (front) root–carries motor information from the spinal cord to the muscles
259
What is the sympathetic and parasympathetic nervous system? What are they a part of? Where do they originate in the spinal cord?
The autonomic nervous system has three major divisions: 1. Sympathetic nervous system 2. Parasympathetic nervous system 3. Enteric nervous system Sympathetic nervous system - A component of the autonomic nervous system that arises from the thoracic and lumbar spinal cord. In general, sympathetic activation prepares the body for action: blood pressure increases, the pupils of the eyes widen, and the heart quickens. This set of reactions is sometimes called simply the “fight or flight” response. Parasympathetic nervous system - A component of the autonomic nervous system that arises from both the cranial nerves and the sacral spinal cord. Generally helps the body to relax, recuperate, and prepare for future action, sometimes called the “rest and digest” response.
260
How does development relate to the way the structures of the brain are categorized as part of the telencephalon, diencephalon, mesencephalon, metencephalon and myelencephalon? DIAGRAM
Neural tube - An embryonic structure with subdivisions that correspond to the future forebrain, midbrain, and hindbrain. The walls of this neural tube are made of cells, and the interior is filled with fluid. A few weeks after conception, the human neural tube begins to show three separate swellings at the head end: the forebrain (or prosencephalon), the midbrain (or mesencephalon), and the hindbrain (or rhombencephalon). About 50 days after conception, the forebrain and hindbrain have already developed clear subdivisions. At the very front of the developing brain is the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.
261
What are the meninges, why are they important?
Meninges are the three protective sheets of tissue—dura mater, pia mater, and arachnoid—that surround the brain and spinal cord. Dura mater -The outermost of the three meninges that surround the brain and spinal cord. Pia mater - the innermost of the three meninges that surround the brain and spinal cord Arachnoid - The thin covering (one of the three meninges) of the brain that lies between the dura mater and pia mater.
262
What is meningitis?
An acute inflammation of the meninges, usually caused by a viral or bacterial infection. Potentially lethal medical emergency characterized in early stages by headache, fever, and stiff neck as the inflamed meninges press on the brain.
263
What is CSF – where is it made, where does it flow, where is it re-absorbed. Do we make what we need on a daily basis?
What is CSF? Cerebrospinal fluid (CSF) - The fluid that fills the cerebral ventricles. where is it made? Choroid plexus - A highly vascular portion of the lining of the ventricles that secretes cerebrospinal fluid. Specialized membrane the lines the lateral ventricles produces CSF by filtering blood. where does it flow? Ventricular system - A system of (CSF) fluid-filled cavities inside the brain. The middle layer of Meninges call Arachnoid - suspends the brain in a bath of cerebrospinal fluid (CSF). where is it re-absorbed? CSF is absorbed back into the circulatory system through: large veins beneath the top of the skull. Do we make what we need on a daily basis? First, it acts mechanically as a shock absorber for the brain: floating in CSF, the brain is protected from sudden movements of the head that would smash it against the inside of the skull. Second, CSF provides a medium for the exchange of materials, including nutrients, between
264
What do the ventricles do?
ventricular system - A system of fluid-filled cavities inside the brain. The CSF circulating through the ventricular system has at least two main functions. First, it acts mechanically as a shock absorber for the brain: floating in CSF, the brain is protected from sudden movements of the head that would smash it against the inside of the skull. Second, CSF provides a medium for the exchange of materials, including nutrients, between blood vessels and brain tissue. lateral ventricle - A complexly shaped lateral portion of the ventricular system within each hemisphere of the brain. third ventricle - The midline ventricle that conducts cerebrospinal fluid from the lateral ventricles to the fourth ventricle. fourth ventricle - The passageway within the pons that receives cerebrospinal fluid from the third ventricle and releases it to surround the brain and spinal cord. It has three small openings allow CSF to exit the ventricular system and circulate over the outer surface of the brain and spinal cord.
265
What behaviours are the four lobes of the brain involved in?
Frontal lobe - The most anterior portion of the cerebral cortex. important for movement and high-level cognition Parietal lobe - Large regions of cortex lying between the frontal and occipital lobes of each cerebral hemisphere. It receives sensory information from the body and participate in spatial cognition. Temporal lobes - Large lateral cortical regions of each cerebral hemisphere, continuous with the parietal lobes posteriorly, and separated from the frontal lobe by the Sylvian fissure. Auditory information damage here can impair hearing the temporal lobes are also particularly associated with the sense of smell, and with aspects of learning and memory. Occipital lobes - Large regions of cortex covering much of the posterior part of each cerebral hemisphere. Receive and process information from the eyes, giving rise to the sense of vision.
266
What is the difference between white and grey matter?
White matter - A shiny layer underneath the cortex that consists largely of axons with white myelin sheaths. Which consists mostly of fiber tracts. It gains its appearance from the whitish fatty myelin that ensheathes and insulates the axons of many neurons. White matter mostly transmits information. Gray matter - Areas of the brain that are dominated by cell bodies and are devoid of myelin. On the exterior is dominated more by nerve cell bodies and dendrites, which are devoid of myelin. A simple view is that gray matter primarily processes information,
267
What is the difference between fissures, gyri and sulci?
The lumpy convolutions of the paired cerebral hemispheres are the result of elaborate folding together of a thick sheet of brain tissue called the cerebral cortex which is made up mostly of neurons and their fibers. The resulting ridges of tissue, called gyri, are separated from each other by furrows called sulci. A fissure is a deep sulcus
268
Be familiar with the three major fissures. DIAGRAM
Sylvian fissure Also called lateral sulcus. A deep fissure that demarcates the temporal lobe.
Central sulcus A fissure that divides the frontal lobe from the parietal lobe.
Longitudinal fissure – the fissure that runs from the back to the front
269
Why are the pre- and post-central gyri important?
Postcentral gyrus - The strip of parietal cortex, just behind the central sulcus, that receives somatosensory information from the entire body. Precentral gyrus - The strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control.
270
What is the limbic system? What is its primary function? Hippocampus, amygdale, cingulate cortex, mammillary bodies – what do they do?
Limbic system - A loosely defined, wide-spread group of brain nuclei that innervate each other to form a network. Curving through each hemisphere, alongside the basal ganglia. It is critical for emotion and learning. Limbic structures near the base of the brain, especially the hypothalamus, help to govern highly motivated behaviors, like sex and aggression, and regulate the hormonal systems of the body. Hippocampus - A medial temporal lobe structure that is important for learning and memory. Amygdala - A group of nuclei in the medial anterior part of the temporal lobe. It has several subdivisions with diverse functions such as emotional regulation and odor perception. Cingulate gyrus - A cortical portion of the limbic system, found in the frontal and parietal midline. Implicated in many cognitive functions, including the direction of attention. Mammillary bodies - are important for emotion, learning, and memory.
271
What are the functions of the superior and inferior colliculi?
Superior colliculi - Paired gray matter structures of the dorsal midbrain that receive visual information and are involved in direction of visual gaze and visual attention to intended stimuli. Inferior colliculi - Paired gray matter structures of the dorsal midbrain that receive auditory information.
272
What are the functions of the substantia nigra, hypothalamus (four behaviours), pituitary?
Hypothalamus - Part of the diencephalon, lying ventral to the thalamus. It is packed with discrete nuclei involved in many vital functions, such as hunger, thirst, temperature regulation, sex, and many more. Furthermore, because the hypothalamus also controls the pituitary gland, it serves as the brain’s main interface with the hormonal systems of the body. Substantia nigra - A brainstem structure in humans that innervates the basal ganglia. Contains neurons that release the transmitter dopamine. Pituitary gland - Also called hypophysis. A small, complex endocrine gland located in a socket at the base of the skull. Includes anterior pituitary and posterior pituitary. Hormone secretion
273
What is the main function of each of the cerebellum, pons, medulla and reticular formation?
Cerebellum - t is involved in the central regulation of movement. Has long been known to be crucial for motor coordination and control, but we now know it also participates in certain aspects of cognition, including learning. Pons - part of the brainstem connecting midbrain to medulla. Within the pons are important motor control and sensory nuclei, including several nuclei from which cranial nerves arise. Reticular formation -An extensive region of the brainstem that is involved in arousal (waking). Variety of behaviors, including sleep and arousal, temperature regulation, and motor control.
274
What are the three main arteries in the brain proper? Please be able to speculate how damage (stroke) to one of these areas might affect behaviour – what would you ‘see’?
Anterior cerebral arteries - Two large arteries, arising from the carotids, that provide blood to the anterior poles and medial surfaces of the cerebral hemispheres. (stroke here would cause damage in movement and high-level cognition, receiving sensory information from the body and participate in spatial cognition.) Middle cerebral arteries - Two large arteries, arising from the carotids, that provide blood to most of the lateral surfaces of the cerebral hemispheres. (stroke here would can impair hearing, the sense of smell, and with aspects of learning and memory) Posterior cerebral arteries - Two large arteries, arising from the basilar artery, that provide blood to posterior aspects of the cerebral hemispheres, cerebellum, and brainstem. (stroke here would cause problems with motor coordination and control, important motor control and sensory nuclei, including several nuclei from which cranial nerves arise and heart problems and death)
