Neuroscience Flashcards
1
Q
What are the three divisions of the nervous system?
A
Central nervous system
Peripheral nervous system
Enteric nervous system
2
Q
What is the difference between CNS and PNS?
A
CNS - the structures of the brain and the spinal chord
PNS - nerves and cell bodies to and from the brain and spinal chord
3
Q
What is the enteric nervous system?
A
The neural cells of the viscera and is often classified as the PNS
4
Q
How many peripheral nerves are there?
A
43
5
Q
What is a nerve?
A
Bundle of axons/neurone processes
Does not contain dendrites
No neuronal cell bodies
6
Q
What does mixed mean (in terms of nerves)?
A
Has both motor and sensory roles
7
Q
What are the layers in the nerve?
A
Each individual axon is surrounded by endoneurium
These are bundled together by perineurium into fascicles
Fascicles are bound together by epineurium
8
Q
How many pairs of cranial nerves are there?
A
12 pairs
9
Q
Are cranial nerves mixed, sensory or motor?
A
All of them
10
Q
What is the most common cranial nerve?
A
Vagus nerve (cranial nerve 10) - 80% of PNS outflow
11
Q
How many spinal nerves are there?
A
31 pairs (5 sets of pairs)
12
Q
Are spinal nerves mixed, sensory or motor?
A
Mixed
13
Q
Are spinal nerves branched?
A
Yes
14
Q
What are dermatomes and what is their clinical use?
A
The patterns of innervation of spinal nerves.
Help neurologists identify sites of damage
15
Q
What are the sub-divisions of the PNS?
A
Somatic (voluntary) and visceral (involuntary)
These are split into afferent and efferent
Efferent visceral is Autonomic which is split into sympathetic and parasympathetic
16
Q
Difference between somatic and autonomic? (in terms of motor axons)
A
Somatic - motor axons go straight to muscle
Autonomic - motor axons synapse with another cell in the ganglion and then to the muscle
17
Q
Which are axons are usually myelinated?
A
Pre ganglionic axons are usually myelinated and post are not
18
Q
What are the differences between the parasympathetic and the sympathetic nervous system?
A
- Both para and sympathetic use acetyl choline and sympathetic uses noradrenaline as well.
- Sympathetic ganglia lie closer to target as axons are shorter
- sympathetic axons can connect to multiple ganglion
19
Q
Name some key historical figures in the study neuroscience
A
Huong Ti - canon of internal medicine Galen - First to use animals Aristotle - heart Al Hazen - eye as an imaging system Al - Zahrawi - Neurosurgery
20
Q
How and why has the use of the squid giant axon improved neuroscience?
A
Allowed the determination of ion flows in action potentials
It has a large diameter and is easy to dissection
21
Q
How and why has the use of worms (C.elegans) improved neuroscience?
A
The model system for developmental cell death (apoptosis)
They are fully mapped
22
Q
How and why has the use of flies (Drosophila) improved neuroscience?
A
Identification of gene regualting (e.g. pax-6 development)
23
Q
How and why has the use of frogs (Xenopus) improved neuroscience?
A
Usefull for:
- Nerve conduction velocity
- Ca2+ release
- How axons grow
- How nerves pathfind
24
Q
How and why has the use of chicks (Gallus) improved neuroscience?
A
Allowed development in transplantation and understanding of nerve growth factor
Allows easy embryonic manipulation
25
How and why has the use of birds improved neuroscience?
Behavioural studies e.g.. imprinting
26
How and why has the use of mammals improved neuroscience?
- Dogs to map motor cortex, chemical neurotransmission and behaviour (pavlovian classical conditioning)
- Cats dogs and apes used to understand reflexes and motor control
- Cats dogs and rabbits used to formulate the autonomic nervous system
- Rats used for operant conditioning by skinner
- Mice - Molecular dissection of behaviour and disease
27
Name some neural tube defects
Spina Bidfida - failure of the neural tube to close ( a mild form is dimples at the bottom of the spine)
Anencephaly
28
How can you prevent most neural tube defects?
Folic acid - mother needs to take at very start of pregnancy for an effect
29
What are the primary brain vesicles? (draw it)
Prosencephalon
Mesencephalon
Rhombencephalon
http://droualb.faculty.mjc.edu/Lecture%20Notes/Unit%205
/chapter_15_the_brain%20Spring%2007with%20figures.htm
30
What are the secondary brain vesicles?
Change after 5 weeks
- Telencephalon - develops
- Diencephalon - from the prosencephalon
- Mesencephalon
- Metencephalon and Mylencephalon - from Rhombencephalon
http://droualb.faculty.mjc.edu/Lecture%20Notes/Unit%205
/chapter_15_the_brain%20Spring%2007with%20figures.htm
31
What is the difference between grey and white matter?
White - Myelinated axons
| Grey - Neuronal cell bodies
32
What is the structure of the spinal chord?
White and grey matter around a central canal encased in a bony vertebrate. Dorsal and ventral roots which have ganglia (looks like a swelling)
http://www.easynotecards.com/notecard_set/33616
33
What is the function of the dorsal and ventral roots of the spinal cord?
Dorsal - carries sensory input in
| Ventral - carries motor commands out
34
What causes a slipped disc?
Cartilage supporting the root may compress the nerve and cause pain
35
What is an interneuron?
They connect between sensory and motor neurones and are important in reflexes
36
What does crossing over mean?
Sensory and motor inputs/outputs on the left of the body may be dealt with on the right side of the brain
37
What are the meninges of the spinal cord?
- Pia mater (closest to neural tissue)
- Arachnoid
- Dura mater
They are layers of membrane to protect the spinal cord
38
What are the meninges of the brain
Continuous with those of the spinal cord
- Pia mater
- Subarachnoid space
- Arachnoid
- Subdural space
- Dura sinus
- Endosteal
https://www.shutterstock.com/image-vector/meninges-brain-labeled-24964390
39
What is the cerebrospinal fluid?
Fluid found in the central canal, brain ventricles and subarachnoid space
40
What is the function of cerebrospinal fluid?
Moves and cushions the CNS and reduces its molecular weight
| Trauma - lose fluid and molecular weight increases - compromise blood flow
41
How can you sample cerebrospinal fluid?
Lumbar puncture between 3rd and 4th vertebrate
42
Disorders of the cerebrospinal fluid
Hydrocephalus - build up of fluid in the brain. If internal can be life threatening
43
What is the blood brain barrier?
A physiological barrier - selective semi permeable membrane that separates the circulating blood from the cerebrospinal fluid
44
What is the blood brain barrier made up of?
Astrocytes, tight junctions and capillary endothelial cells
45
What are the four divisions of the brain?
- Brainstem
- Diencephalon
- Cerebellum
- Cerebrum
46
What is the brainstem composed of and where is it located ?
- Medulla oblongata (bottom)
- Pons (middle)
- Mesencephalon (top)
Directly connected to the spinal chord
http://humannervoussystem2.weebly.com/brain-anatomy.html
47
Define decussation
Crossing over from one side to another: usually in the pyramids in the medulla oblongata
48
What is the function of the medulla oblongata?
- Respiratory rhythmicity center
| - Cardiovascular centre
49
What are the major features of the medulla oblongata?
- Fibre tracts
- Nuclei
- Olives (send presses to cerebellum)
- Nerve roots - site of origin of many cranial nerves
Large lesions cause death
50
What is the function of the pons?
Was thought to bridge the sides of the cerebellum
Connects to cerebellum via peduncles
Respiratory centre
51
What is the function of the mesencephalon/midbrain?
Visual and auditory reflexes
| connects to cerebral hemispheres by cerebral peduncles
52
Where is the cerebellum located?
At the back of the brain:
| http://humannervoussystem2.weebly.com/brain-anatomy.html
53
What is the structure of the cerebellum?
- Folia
- Layers - Purkinje cells
- Deep nuclei (clustered neurones)
- White matter
54
What is the role of the cerebellum?
- Muscle tone
- Co-ordiantion
- Motor error - checking
- Learning
55
What is cerebral ataxia?
Loss od cerebral neurones leading to jerky and imprecise movements
56
What is the reticular formation?
Cluster of neurones in the brainstem that controls the cardiovascular centres and reticular activating system (cardiac rhythm, alertness and emotion)
57
Where is the diencephalon located?
Part of the forebrain that links the midbrain and the cerebrum.
58
What is the structure of the diencephalon?
- Thalamus
- Hypothalamus
- Pineal
https: //s-media-cache-ak0.pinimg.com/736x/49/78/49/49
7849f7cb770365d631b45b927de7b5. jpg
59
What is the function of the thalamus?
It is the processing and relay centre
- All special senses except smell
- Motor role
- Arousal
- Emotions
60
What is the role of the pineal?
Its an endocrine organ that secretes melatonin and serotonin
61
What is the role of the hypothalamus?
Wide variety:
- eating
- drinking
- sexual behaviour
- stress
62
What are the lobes of the cerebrum?
- Frontal
- Parietal
- Occipital
- Temporal
- Central
- Limbic
63
What are the layers of cerebral cortex?
- Molecular
- External granular
- External pyramidal
- Internal granular
- Internal pyramidal
- Fusiform layer
64
What is the cerebral cortex?
The outer cortex of the cerebrum surrounding the white matter and deep nuclei
65
Who was Phineas Gage?
Metal bar went though his frontal lobe
| Changed his personality
66
What is Broca's Aphasia?
```
Left frontal damage
Causes impaired speech
- grammar
- syntax
- word structure
```
67
What is Wernicke's Aphasia?
Posterior temporal lobe damage
| affects language comprehension
68
What is the associating cortex?
The most cortical area and is highly developed in man. Input from many sources
69
What is the left hemisphere responsible for?
Speech
Calculation
Analysis
70
What is the right hemisphere responsible for?
Spatial
Conceptual
Artistic
71
What are basal ganglia?
Neuronal cell bodies
| Ganglia and nuclei are interchangeable terms
72
What diseases are related to faults in the basal ganglia?
Parkinsons
Huntingtons
Because they are important for movement and switching between tasks
73
Where are basal ganglia found?
Caudate and putamen
Globus pallidus
Subthalamic nucleus
Mesencephalon
74
What is the role of the limbic system?
- Memory
- Emotions
- Motivation
75
What parts of the brain are involved in the limbic system?
- Limbic lobe
- Thalamus
- Hypothalamus
- Hippocampus
- Amygdala
76
What are association fibres?
Link areas within a hemispheres
77
What are commissural fibres?
Connect between hemispheres
78
What are projection fibres?
Link to non-cortical areas
79
Examples of association fibres
- Corpus callosum
- Anterior commisure
- longitudinal fasciculi
80
Name the brain ventricles
- Lateral ventricles (right and left)
- Third ventricles
- Fourth ventricles
https: //schoolworkhelper.net/ventricles-and-meninges/
81
What are ependymal cells?
A type of glial cells that line the cerebrospinal fluid filled ventricles and provide a supporting role
82
What is a neurone?
An excitable cell - will respond to an electrical impulse with an action potential
83
What is a glial cell?
A non excitable support cell
84
Give an example of a unipolar neurone
Dorsal root ganglia
85
Give an example of a bipolar neurone
Retinal bipolar cells
86
Give examples of multipolar neurones?
- Motor neurones
- Purkinje cells
- Pyramidal cells
- Cerebellar granule cells (axon branches of the dendrites)
87
Give an example of an oddity
- Olefactory receptor and olefcatory granule cells (smell)
88
What are the main types of glial cells?
- Macroglia
- Microglia
- Ependyma
89
Give some examples of macroglia cells
- Astrocytes
- Schwann cells
- Oligodendrocytes
90
What is the difference between fibrous and protoplasmic astrocytes?
Fibrous - white matter and has many intermediate filaments
| Protoplasmic - grey matter, shorter processes and few intermediate filaments
91
Give some specialised astrocytes
Retinal muller cells - columnar cells
| Radial glia - span from playing to purkinje cells
92
Name the three roles of astrocytes
1. Spatial buffering
2. Neurotransmitter uptake
3. Glucose metabolism
93
What is the spatial buffering? (astrocytes)
Spatial buffering regulates the [k+] as active neurones release k+ and astrocytes are very permeable to them
For example muller cells up take k+ in the retina to reduce [k+] near the photoreceptors.
94
How are neurotransmitters taken up in astrocytes?
Glutamate into astrocytes which is converted into glutamine and then recycled in neurones
95
How do astrocytes aid glucose metabolism?
Astrocytes store glycogen
96
Microglia facts
- Short spikes processes
- Wide distribution
- Derived from circulatory monocytes
- Function in phagocytosis
97
Name types of ependyma cells
Ependymocytes (majority)
| Tanycytes
98
How many months into development does myelination begin?
5 months in human and 10 days postnatal in rats
99
When are the basic structures of the nervous system developed?
3 months
100
When are the primary vesicles developed?
6 weeks
101
How does the composition of myelin change in development?
Galactolipids increase
| Protein components increase
102
At what age does myelination finish?
Mostly over by 2 years but some can continue into late teens
103
How does rubella affect a developing foetus?
Targets cells that are dividing at the time:
- 6th week - cataracts
- 9th week - deafness
- 5th-10th week - cardiac malformation
- 2nd trimester - CNS disorder
104
What are the symptoms of fatal alcohol syndrome?
- Facial abnormalities
- Microcephaly - smaller brain due ti loss of cells
- loss of fibres
- Disturbed migration
- Irritability
105
What causes fatal alcohol syndrome?
Alcohol taken by mother is passed across the placenta
| Foetus doesn't clear alcohol very well so foetal levels are higher
106
How does drug abuse affect a developing foetus?
Opiates - foetus will become dependant
Cocaine - hypoxia, abortion, lower cognition
Ecstasy - long term effects on hippocampus
Cannabis - long term cognitive effects
107
When does the foetus feel pain?
Pain requires connection of receptors, sensory neurones, thalamus and cortex.
- innervation of dermal skin from 28 weeks
- Dorsal root ganglia connect to spinal cord from 8 weeks
- Reflex responses from 23 weeks
- connections from the thalamus to cortex from 24 weeks
- Evoked potentials in the cortex from 29 weeks
- Cortical repossess after 24 weeks
108
When does taste and smell develop?
They are well developed at birth
Evidence:
- Differentiate from mother/non mothers breasts
- Bottle fed babies prefer any lactating female
109
When is hearing developed?
- Responsive at birth
| - Excellent discriminators of language sounds
110
When does vision develop?
- Vision not well developed at birth
- Eyes open and sensitive from 7 months
- Retinal cells sparse and not mature
- optic nerves mot myelinated
111
How long does the stepping reflex last?
6 weeks
112
How long does the swimming reflex?
4-6 months
| Not all babies
113
What is the babinski reflex?
Toes fan when sole is stroked
Adults cured toes
If toes fan in adults then descending motor tract damage
114
Does myelin surround all axons?
No - more non myelinated than myelinated
115
What glial cells produce myelin?
PNS - Schwann cells
| CNS - Oligodendrocytes
116
How do Schwann cells and oligodendrocytes myelinate axons?
Schwann cells - membrane of Schwann cells wrapped around individuals axons
Oligodendrocytes - sends out processes and myelinate several axons at once
117
What is myelin made of?
Water - 40%
Dry lipid - 70-85%
Protein - 15-30%
118
Myelin in the PNS has less.....
cerebroside and sulfatide
| CNS has more sphingomyelin
119
What are the the major proteins in myelin?
Myelin basic protein - shiverer mice - die early
Proteolipid protein - in Jimpy mutant mouse, there are is little myelin and severe loss of oligodendrocytes
Also enzymes and IG's
120
What is multiple sclerosis?
An auto immune disease that causes primary demyelination disease. Macrophage and protease activity degrades myelin. Plaques develop
121
Who gets MS?
Onsets 20-40's
More common in white females
30% concordance in identical twins - not all genetic
122
What treatments are available for multiple sclerosis?
- Steroids
- Interferons - target immune response
- Haemopoietic stem cells
- Diet - vitamin D
123
What is Guillan-barre syndrome?
An autoimmune disease that causes primary demyelination and occurs after a viral/bacterial infection
124
How does the nervous system allow an organism to react rapidly to its environment?
- Electrical activity to allow neurones to receive and transmit signals
- Chemical messengers between and within cells
125
What are the two types of electrical signals?
Action potentials
| Graded potentials
126
What is the difference between an action and a graded potential?
Action potentials - fixed size, all or nothing signals, CAN pass either way but tend to go one one, coded by frequency
Graded potentials - variable size, pass both ways and are coded by size and vary according to the strength of a stimulus
127
Why do neurones have a resting potential?
Inevitable consequence of:
- Selectively permeable membrane
- Unequal distribution of charged molecules
- Physical forces
128
What physical forces control ion movements in generation of an action potential?
- Diffusion - from high to low
| - Electrical current - positive to negative
129
How do you measure membrane potential?
Using a KCl electrolyte and a Cl electrode
| Negative membrane potential is essential
130
What ion pumps are used in the generation of an action potential?
Ion channels set up ionic concentration gradients found in neurones
- Na+/k+ ATPase
- Ca2+ pumps
131
What is an equilibrium potential?
The membrane potential that would `be achieved in a neurone if the membrane was selectively permeable to that ion
132
How is the equilibrium potential for an ion calculated?
The Nernst Equation
| do practice questions
133
The Goldman Equation
How you calculate resting membrane potential at equilibrium for k+ taking into account other ions such as Na+ (combined potentials)
134
What is the purpose of Na+/K+ pump in a resting potential?
Na+/K+ pump produces and maintains large K+ concentration gradient across neuronal membrane meaning at rest the membrane is highly permeable to K+ ions
135
What are the properties of the action potential?
- Rapid and reversible change in membrane potential from negative to positive
- All the same size and duration
- Do not decrease as conducted down the axons
- Different types of excitable cells may have different types of action potentials
136
What are the characteristic features of an action potential?
- Resting membrane potential = -70mv
- Depolarisation above threshold level
- Repolarise and overshoots fall below threshold level
- Action potential is triggered by Na+ permeability
137
What is the structure of the voltage gated Na+?
- 6 transmembrane domains
- Channels open in response to depolarisation
- Concentration of charge near plasma membrane affects voltage sensors
- Na+ channels inactivate in a time and voltage dependant manner
138
Name some poisons that affect the generation of action potentials?
- Tetrodotoxins - inhibits voltage gated ion channels
| - Lidocaine - inhibits Na+ channels - lethal
139
What factors influence conduction velocity?
- How leaky the membrane is
- Thickness of the axon - less resistance id the axon is bigger
- Myelination - prevents current loss along an axon
140
Why are humans axons myelinated?
Because humans have a space constraint so the axons can't be that large
141
Why aren't all axons myelinated?
Energy and space constraint
142
What sized axons are myelinated?
Greater than 1 micrometer are usually myelinated
| Small unmyelinated around 0.2-1.5 micrometers
143
Dendrites function
They have voltage sensitivite channels but don't usually produce action potentials
Mostly encode information with graded potentials
Many dendrites can respond to the same stimulus - high intensity
144
What affects the intensity of a stimulus?
Action potential frequency
145
What type of potential can produce a higher intensity?
Graded potentials as they can summate
146
What are the two types of summation?
Spacial summation - multiple axons synapsing to the same place
Temporal summation - Multiple stimuli add together to create a response - one stimuli might not be enough to get move the threshold level
147
What are electrical synapses?
Connect two neurones that are dung the same thing
| Exist in glial cells and in cardiac and smooth muscle
148
What is an EPSP?
Excitatory postsynaptic potential
More likely for a neurone to fire an action potential
Inhibitory inputs can stop EPSPs
149
What are the different types of synapse?
- Axodendritic
- Axosomatic
- Axoaxomic (often inhibitory)
- Dendrodendric - rarer
150
What is often used as a model to study synapses?
Neuromuscular junctions
151
Why are synapses needed?
Allows flow of information in different directions
| Allows the processing of information that is complex elaborate and flexible
152
What is the difference between convergence and divergence?
Convergence - Cells can have many inputs
| Divergence - Cells can send processes to multiple different cells
153
What are the standard features of chemical synapses?
- Axon with a swelling
- Secretory vesicles
- Synaptic cleft with 20-50nm gap
- Adhesion junction
- Active zones where neurotransmitters are released
154
Active zones
Synapses can release neurotransmitters from more than one active zone
Large synapses usually have more active zones
155
Name the types of neurotransmitters
Amino acids - GABA, Glysiine
Biogenic amines - Dopamine, Serotinin, histamine
Neuropeptides - B - endorphin
156
List the steps in neurotransmission
1. Synthesis of transmitters in presynaptic cells
2. Stored in lipid bound bags
3. Release of transmitters into synaptic cleft
4. Post synaptic effect
5. Inactivate of transmitter to terminate the cell-cell communication
157
How are neurotransmitters synthesised and stored?
Neuropeptides are made by ribosomes and transported in secretory granules to the active zone where they are stored away from the membrane so they don't fuse with the membrane
Also kept close enough for rapid release
158
How are neurotransmitters released from the pre synaptic membrane?
- Presynaptic membrane is depolarised by action potential causing an influx of Ca2+ though voltage gated Ca2+ channels
- Causes restructure of docking the synaptic vesicle causing it to fuse with me membrane
- Exoctosis
159
What is the quantal effect?
Synaptic vesicles contain 35-30nm of neurotransmitters
| Synaptic vesicles are of a similar size so they can be considered as 1 quanta
160
What are the main types of receptors in the synapse?
- Ligand-gated ion channel
| - G-protein coupled receptor - slower transmission
161
How is an EPSP generated?
Na+ channels open
Generates an excitatory post synaptic potential (EPSP)
Individual may not be enough to reach threshold level so summation may occur
162
How is an IPSP generated?
Cl- channels open
Generates a inhibitory post synaptic potential
Hyperpolarises membrane making it harder to reach threshold - less chance of action potential
163
How is the transmission of an action potential terminated?
1. Post synaptic break down
2. Diffuse away
3. Reuptake by postsynaptic terminal
164
What are the differences between chemical and electrical synapses
- Chemical allows more types of communication
- Chemical has more flexibility
- chemical signals of different types being released from a stimulating neurotransmitters
165
What are the criteria for neurotransmitters?
- Present in presynaptic terminals
- Released in response to stimulation
- Able to interact with postsynaptic receptors
- Rapidly removed from the synapse
166
What are the characteristics of amino acid and amine neurotransmitters?
- Small molecules
- stored and released from synaptic vesicles
- Activate both ligand gated channel receptors and G coupled receptors
167
What are the characteristics of peptide neurotransmitters?
- Large molecules
- Stored in secretory granules
- Only activate G coupled receptors
168
What is Dales principle?
A single neurone has only one transmitter
| he was wrong
169
What is the role of glutamate as a neurotransmitter?
- Binds to various receptors eg. NMDA and AMPA
| - AMPA important in fast transmission
170
What is the most common excitatory transmitter in the CNS?
Glutamate
171
Why do NMDA receptors have to be indirectly activated by another transmitter?
Because they have a voltage dependant Mg2+ block
| When partially depolarised Mg2+ moves out
172
What is the most common inhibitory transmitter in the brain?
GABA
173
How is GABA formed and where is it found?
Glutamate --> GABA using the Glutamic acid decarboxylase enzyme
Found mainly in the cortex and the striatum
174
What happens if there is too much or too little GABA?
Too much - Coma
| Too little - seizures
175
How does presynaptic inhibition occur?
Action potential arrives at neurone causing the release of GABA. This inactivated Ca2+ channels and therefore reduces neurotransmitter released reducing its affect on the post synaptic neurone
One neurone surpasses the action of another
176
How do anxiolytic drugs work?
e.g.. alcohol, benzodiazepine
| bind to GABA receptors and stimulate its response to GABA
177
What happens due to the loss of GABA receptors?
Panic attacks
178
How do opiates have an effect?
They bind to opiate receptors in the brain that are present due to natural opiates in the body such as endorphins
179
Where are opiate receptors present?
- Spinal - block pain
- Amygdala - regulates emotion
- Frontal cortex - Cognitive
- Brain stem - depress respiration and cough reflex
180
What type of receptors are opiate receptors?
G coupled receptors
181
Name some therapeutic uses of opiates
- Analgesia - reduces perception to pain
- Intestinal disorders - deceases dehydration
- Antitussive - cough suppressant
182
Problems with the use of opiates
- Tolerance and dependancy
- Euphoric effects are linked
- Relieve dull visceral pain better than sharp pain
- Analgesia (inability to feel pain) and dependence liability
183
What are the common features of the diffuse modulatory systems of the brain?
Core nuclei in the central part of the brain. The neurones may contact large numbers of postsynaptic neurones
184
What neurotransmitters are involved in the diffuse modulatory systems?
Catecholamines
Serotonin
ACh
185
Where in the brain is ACh found?
- Autonomic nerves
- Neuromuscular junction
- Basal forebrain
- Hippocampus
186
Name some examples of things that prevent the release of ACh
- Botulism - botox
| - Black widow spider
187
Name some AChE inhibitors?
- Nerve gas
- Insecticides
- Alzheimers treatments - not much success
188
What are the catecholamine systems?
Regions of the nervous systems associated with movement, mood, attention, visceral function
- Dopamine system - 'Pleasure centre'
- Noradrenaline system - memory, anxiety
189
How are catecholamines synthesised?
Tyrosin --> dopa --> Dopamine --> Norepinephrine --> Epinephrine
190
How many people does Parkinson's disease affect?
1 in 200 world wide
191
What are the symptoms of Parkinson's disease?
- Tremor
- Rigidity
- Akinesia (loss of voluntary movement)
- Postural changes
- Slurred speech
- No sensory loss
- Normal cognitive function
192
What part of the brain is affected by Parkinson's disease?
Dopamine containing areas of the brain are lost
193
What is the function of the striatum?
Inhibits motor function
194
What is the role of dopamine in the striatum?
It inhibits cells of the striatum (decreasing their inhibitory action). In Parkinson's disease this inhibition is lost from dopamine meaning an increase in motor function
195
Name some drugs that increase dopamine levels
- L-Dopa
- Amphetamine - increases release
- Cocaine - blocks reuptake
- MAO inhibitor
- D2 agonists
196
What are the problems with the long term uses of L-Dopa as a treatment for Parkinson's?
- The drug becomes ineffective
| - Can lead to chronic L-Dopa syndrome which can cause sudden immobility
197
What are the disadvantages of taking antagonists on dopamine?
Dopamine inhibits the production of prolactin and antagonists may results in its overproduction - can cause lactation in males and females
198
How are catecholamines removed?
- reuptake into presynaptic terminals
- Metabolised by COMT - in the cytoplasm and by MOA - on outer mitochondrial membranes
MOA -A - noradrenaline
MOA -B - dopamine
199
What are MOA inhibitors used as treatments for?
- Depression - increase NA
| - Parkinsons - increase DA
200
What are the functions of serotonin (5-HT)?
- Arousal
- Cardiac rhythms
- Mood
- Aggression
201
Name some treatments of depression?
- Tricyclics - block uptake of NA and 5 -HT
- SSRI's - inhibit serotonin reuptake
- MOA - A inhibitors
202
What type of receptors are classified based on their modality?
Chemo, thermo, mechano
203
What type of receptors are classified based on their origin?
- Interoceptors - internal organs, visceral pain
- Proprioreceptors - muscles, tendons, joints
- Nociceptors - Hugh threshold mechano and thermoreceptors
- Exteroceptors - vision, hearing, touch
204
What type of information do all sensory receptors transmit?
- Modality
- Location
- Intensity
- Duration
205
What is sensory modality?
What is perceived after a stimulus
| - eg. vision, taste, smell, hearing
206
How is location transmitted by a sensory receptors?
Through receptive fields and projection pathways to CNS:
- stimuli diverge an converge at different synapses
- lateral inhibition occurs
207
What is the function of inhibitory synapses?
- Prevent unrestricted spread of excitation
- descending inhibition - higher control - block transmission to concentrate on other stimuli
- feedback inhibition - gain adjustment
- lateral inhibition - block neurone next to it - e.g.. increases contrast in the eye
208
How is intensity transmitted in sensory receptors?
- Increases frequency of stimuli = higher intensity
- Recruitment of more neurones
- Low threshold fibres for weak stimuli
209
How is duration transmitted in sensory receptors?
Phasic receptors - burst, fast adaption (response quickly diminished)
Tonic receptors - slow adaption (produces action potential for long time)
210
Define sensory transduction
Conversion of sensory information from one form to another
211
What are receptive fields?
Particular region that will cause the firing of a neurone in response to a stimuli eg. body surface (back, fingers)
212
How does sensory transduction occur?
- Stimulus induces local change in membrane permeability
- Ions flow across the membrane
- Receptor generates a potential
- Release of neurotransmitter onto nerve
- Burst of action potentials from nerve
213
What wavelength is visible light?
400-700nm
214
What are the three layers of the eye?
- Tunica fibrosa
- Tunica vasculosa
- Tunica interna
215
What is the tunica fibrosa layer of the eye?
The partly transparent collagen layer that surrounds the eye and stops it from bursting when the pressure increases
216
How is the tunica fibrosa layer of the eye transparent?
The cornea has to be transparent to allow us to see and it does this by undergoing apoptosis but not enough to actually kill the cells
217
What is the tunica vasculosa layer of the eye?
Layer of choroid (full of blood vessels) for nutritional support
Ciliary body
Iris
218
What is the tunica interna layer of the eye?
- Retina
| - Optic nerve - papilla and lamina cribrosa
219
What is the role of ciliary body in the eye?
- The ciliary body secretes fluid into the anterior and posterior chambers. The canal of schlemm drains the fluid. The rate of secretion and drainage needs to be equal in order to maintain the pressure.
- The fluid also provides nutrients required for the lens and the cornea
220
What is the most important part of the eye in forming an image and why?
- Lens - best refractive index of 1.41
| However cornea and aqueous humour have similar refractive indexes (around 1.34)
221
What are the most common causes of blindness?
- Cataracts - clouding of lens - treatable with laser eye surgery
- Glaucoma - increases eye pressure leads to retinal degeneration
222
What is the role of the iris in the eye?
Regulates light level
| - Pupils constrict and dilate using smooth muscle
223
What is the photopupillary reflex?
If you illuminate one eye the other will constrict as well
| - responds to a change in intensity
224
Why is the photopupillary reflex tested after an accident?
To check that the connection with the CNS is undamaged.
- The optic nerve goes to the pre-tectal region in the pons
- Feedback loop back to the iris by ciliary nerves leading to the reflex
225
What occurs in the eye in the near response?
- Convergence - eyes move together
- Miosis - constriction of the pupils
- Lens accommodation - ligaments pull and distort shape or the lens so the eye can focus
226
Why do animals have the photoreceptive rod and cone cells at the back of the eye?
So that it is close to the pigment epithelium which contain phagocytes - which breakdown damaged photoreceptors and allow its repair
227
How are rod and cone cells structured in the eye?
The majority of the cell in a line below the pigment epithelium and then all of the nuclei are in a layer below that together
228
What are the four lingual papillae on the human tongue?
- Filform
- Foliate
- Fungiform
- Valiate
229
What are the characteristics of the filiform on the tongue?
- Spiked
- No taste buds
- Texture
- Most abundant
230
What are the characteristics of the foliate on the tongue?
- least abundant
| - gone by 2-3 years of age
231
What are the characteristics of the fungiform on the tongue?
- 3 apical taste buds
| - tip and sides of tongue
232
What are the characteristics of the villate on the tongue?
- Large
- back of tongue
- contains about half of the taste buds
233
How many taste buds are there?
4000
234
What parts of the tongue are associated with particular tastes?
- sweet - tip of tongue
- salty and sour middle of the side of the tongue
- texture -middle
- bitter at the back
235
Why are the bitter taste buds located at the back of the tongue?
To activate the gag reflex as many toxic substances taste bitter
236
Why are the sweet sour and umami taste buds located near the front of the tongue?
Because salty foods contain essential electrolytes (Na and K), sweet foods are high in energy, sour foods are often things like citrus fruits and umami foods like meat contain essential amino acids
237
Why does the salt pathway differ to sweet and umami?
Salt can transform from appetite stimulus to an aversive one. This allows the regulation of salt intake
- High salt can activate the bitter and sour pathways to stop you from any more intake
238
How many odours can be detected in the olfactory system?
2000-4000
239
Does the olfactory system adapt quickly or slowly to a stimulus?
Quickly by synaptic inhibition
240
How does sensory transduction in the olfactory system occur?
- Odorant binding proteins in mucus binds to odorant receptor
- cAMP is the second messenger
- Opens Na+ and Ca2+ channels allowing an action potential
The nerves are unmyelinated
241
What is the olfactory bulb?
An extension of the brain from the cerebrum that drops nerves into the nasal cavity
242
What does the amplitude of a sound wave convey?
Sound intensity
243
What is the range of human hearing?
20-20000Hz
244
What is the speech range of hearing?
1-7KHz
245
What is the benefit having two ears?
Localises sound - by calculating the delay of sound between the two ears:
- distance between ears/speed of sound = 1/2ms delay
246
What bones are present in the middle ear?
- Malleus
- Incus
- Stapes
247
What is the purpose of the middle ear?
To focus sound - focuses large amount of sound in a small area
248
Why is there a long coiled basilar membrane in the cochlea?
To know the frequency - high if one end vibrates and then low if the other vibrates
249
What is the basilar membrane?
The membrane in the cochlea containing the nerves and collagen hair cells
250
What is the organ of corti?
Part of the cochlea situated on the basilar membrane and has hair cells protruding from it
251
What is the role of tip links on hair cells?
Tip links connect the stereocilia on hair cells together causing them to move together. When hair cells move, the tip links stretches and open K+ channels.
252
What are stereocilia made of?
Actin
253
How do hair cells transduce an action potential?
- Vibration from sound causes seterocillia on hair cells to move opening K+ channels
- K+ moves into the hair cells causing it to depolarise as its resting potential is -70mv
- Causing action potential
254
What is special about the endolymph section of the cochlea?
K+ rich - surrounds organ of corti - providing the K+ that enters the hair cells
255
What is the role of the outer (jumping) hair cells?
The inner ear amplifier - it increases the threshold of activity in the basilar membrane allowing to to be amplified and tuned
256
What is the role of the inner hair cells?
Primary receptors - receive most of the sensory innervation
257
What is the role of the spiral ganglion?
The nerve innervating the hair cell
258
Why is there only one spiral ganglion to one hair cell?
No convergence (unlike retina) to maintain the resolution
259
How is a range intensity shown in the ear?
Multiple nerves with different thresholds on a single hair cell. One threshold might be met by the action potential but the next might not be
260
What is the role of efferent mediated innervation in the ear?
Modifies amplifiers - temporarily lowers thresholds so that the hair cells are less sensitive - a form of proctection
261
What parts of the brain are used to put frequency, intensity and amplification of sound put back together?
- Cochlea nuclei - contains the fastest synapse
- Superior olivary complex - sound localisation and intensity
- Inferior colliculus - responsible for reflexes
- primary auditory cortex
262
What are some differences between auditory system and vestibular system?
- Hair cells are much longer in vestibular
| - Modified tectorial membrane called cupulla in vestibular
263
What is the vestibular - ocular reflex?
It allows the eye muscles to compensate for head movement
264
What is nystagmus?
Constant involuntary movement of the eyes
265
What are the first cells that light hits?
- Ganglion cells
- Bipolar cells
- Then photoreceptors (rod and cone cells)
266
What are the differences between rod and cone photoreceptors?
```
Rod:
- Scotopic - high sensitivity to light
- High convergence - many receptors into one nerve
- Low resolution
- 500nm
Cone:
- Photopic - low sensitivity
- low convergence
- high resolution
- 420 - 558nm
```
267
What is the role of ganglion cells in the eye?
Main output from retina surface to optic nerve
268
What is the role of horizontal and amacrine cells in the eye?
Attach to bipolar cells at the end of processes and do lateral inhibition to allow contrast
269
What is duplicity theory?
You can't have high sensitivity and high resolution in the same receptor. This is why there are separate systems for colour and monochrome systems
270
Are there more rod or cone cells to each optic nerve fibre?
Many rod cells to one optic nerve fibre but only one cone cell
271
What are the photopigments in rod and cone cells?
Rods - rhodopsin
| Cones - Photopsin (red, green, blue)
272
What are the steps in phototransduction?
Rhodopsin binds with transducin GTP activating phosphodiesterase causing hydrolysis of cGMP closing the Na+ channels (in the light)
Ca2+ decreases causing the opening of Na+ channels (in the dark)
Glutamate released
273
What happens in ON bipolar cells?
- Glutamate inhibits ON bipolar cells and causes hyperpolarisation in the dark
- Meaning no signal to the ganglion cells
- Produces IPSP
274
What happens in OFF bipolar cells?
- Glutamate excites OFF bipolar cells and causes depolarisation in the dark
- Produces EPSP
275
What is the most common type of cone cell?
Red - 64%
Green - 32%
Blue - only 4% - must be the most sensitive
276
What are the types of retinal ganglion cells?
- W type (mainly from rods)
- X type (mainly from cones)
- Y type (inputs less types)
- Melanopsin RGCs
277
What is reflex?
A rapid involuntary, yet stereotyped and co-ordianted response to a sensory stimulus
278
Give the characteristics of spinal reflexes?
- Require stimulation
- Are quick
- involuntary and automatic
- stereotyped - occur the same way each time
279
What is the patellar reflex?
- stimulus = tap on the knee
- response = leg kick
- travels through dorsal root ganglia to the spinal chord
- Monosynaptic - one synapse involved
280
What is the stretch (myotactic) reflex?
- important in maintaining body posture
- reciprocal inhibition - motor neurones contract bicep at the same time as interneurons relaxing triceps
- e.g. pouring a drink and keeping the glass up right
281
What is the muscle spindle?
A proprioceptor - a sense organ that monitors position and movement
Found in most striated muscle and are abundant in muscles involved in fine motor control
282
Define proprioception
The sense of the position of parts of the body relative to other parts
283
Waterman had a viral infection that caused loss of proprioceptors, what did this do?
He was unable to coordinate movement - he taught himself to move again by visually monitoring his actions. If dark he can't do this
284
What is the difference in function between the Golgi tendon organ and the muscle spindles?
Muscle spindles detect muscle tension due to stretching but GTO detect muscle tension due to contraction
285
What is the Golgi tendon reflex?
It is a negative feedback circuit that regulates muscle tension and protects the muscle from damage when a large force is generated
286
What is the flexor reflex?
The quick contraction of flexor muscles to withdraw a limb from an injurious stimulus
- polysynaptic reflex despite it being quick
287
What is the parallel after-discharge circuit?
Stimulus activates multiple pathways with different number of synapses to cross to reach response
Will take different times for it to pass creating a response for a continuous period
288
What are used to relax extensor muscles in the flexor and stretch reflexes?
Excitatory interneurones
289
What is the crossed extensor reflex?
provides postural support for another response
| eg. in flexor reflex, rapid withdrawal of a leg will result in the extension of the other leg to maintain the balance
290
What are central pattern generators?
Local circuits produce a pattern of alternating flexion an extension caused by inhibition across the midline
291
Give an example of a central pattern generator?
Animals walking repeatedly, extending an flexing the legs. If spinal cord cut then co-ordiaton between the limbs continue
292
What is the role of meissner (tactile) corpuscles?
A sensory receptor whos modality is light touch, texture and is very sensitive
Found in lips, palms
293
What is the role of pacinian corpuscles?
Sensory receptor whos modality is eep pressure, vibration
| Found in dermis, joint capsules
294
What is the role of ruffuni corpuscles?
Sensory receptor whos modality is heavy touch, pressure
| Found in dermis, joint capsules
295
What is the role of Merkel (tactile) discs corpuscles?
Sensory receptor whos modality is light touch, texture, edges
Found in superficial skin (epidermis)
296
What is the role of free nerve ending corpuscles?
Sensory receptors - modality is pain, heat
| Found in epithelia
297
What is the difference between a rapidly adapting response (phasic) and a slowly adaptive response (tonic)?
A rapidly adapting gives info about changes in stimuli as stimuli quickly stops
A slowly adapting gives info about the persistence of the stimulus as the receptors continue to respond
298
How are primary afferent axons classified?
According to conduction velocity (faster larger diameter)
299
How are axons coming from the skin and muscle classified differently?
Axons coming from skin are classified by letters and sub classified by greek letters
Axons coming from muscle are classified by Roman numerals
300
How are cell bodies organised in the dorsal root ganglia?
The cell bodies of sensory neurones are grouped based on function in the DRG and their projections are in layers in the dorsal horn
301
What is the Medial Lemniscal tracts?
One of the two routes that sensory information moves through to get to the brain
- Carry mechanoreceptive and proprioceptive signals to the thalamus
302
What is the Spinothalamic tract?
One of the two routes that sensory information moves through to get to the brain
- Carries pain and temperature signals to the thalamus
303
What is the role of the three neurones that sensory information travels through to reach the brain?
- First-order neurones detect the stimulus and transmit to the spinal cord
- Second-order neurones relay the signal to the thalamus - gateway to the cortex
- Third-order carry the signal from the thalamus to the cortex
304
Are 1st, 2nd and 3rd order axons for upper and lower body lateral or medial as they move up the medial lemniscal system?
- In 1st order axons from the upper body - lateral and from lower body - medial (closest to the midline)
- 2nd order - they cross the midline and swap over (upper is medial)
- 3rd order - they cross over each other again returning their topology to original (upper is lateral and lower is medial)
305
What does the axons pathways in the medial lemniscal system?
A topographic map
306
What is a dermatome?
Each sensory ganglion innervates a specific region of skin called a dermatome
- can be used clinically to see CNS damage
- develop from a somite in an embryo
307
What is a receptive field?
The area that a sensory neurone can receive a stimulus
308
How can you measure the size of a receptive field?
If a person can differentiate between two small sharp points close together then they are different receptive fields
309
Which parts of the body has larger/smaller receptive fields?
Finger tips - small - more precision
| Arms/legs - large
310
Is the cortical representation proportional to the physical size of the body part?
No hands in humans have large cortical representation but aren't that large same for whiskers in some mammals
However they are linked to the behavioural significance of the area
311
Why does pain differ to the other senses?
Because it's behavioural and not actually physical
312
Why is pain essential for survival?
Because without it, the individual would not know that what they were doing or experiencing was damaging them
313
What are the two theories of pain?
- Specificity theory
| - Convergence theory
314
What is the specifiicity theory?
Says that pain is a distinct sensation that is transmitted by specific receptors to pain areas in the brain
315
What is the convergence theory?
Says that pain is an integrated plastic state represented by a pattern of convergent somatosensory activity within a distributed network
316
What are nociceptors?
Afferents with free nerve endings - pain receptors
317
Give an example of evidence for nociceptors as a receptor for pain?
Thermoreceptors are stimulated at a low temperature. As the temperature rises (stimulus increases) nociceptors start to become active - feel pain
318
What is the difference between fast and slow pain?
- Fast pain is sharp and immediate and can be mimicked by stimulation of Adelta nociceptors
- Slow pain is more delayed and longer lasting and can be mimicked by stimulation of C nociceptors
319
What is a molecular pain receptor?
A specific molecular receptor associated with nociceptors nerve endings that are activated by heat
320
Give an example of a molecular pain receptor
The capsaicin receptor (TRPV1) - activated at 45ºc and by capsaicin ( a component in chilis)
321
What are the two components in the pathways carrying nociceptive info to the brain?
- Sensory discriminative (signals location and intensity)
- Affective - motivational
(signals unpleasantness)
322
What does the activity in the cortex indicate about pain?
That this region of the cortex does respond to a painful stimuli and that the response correlates to the intensity of pain
323
What parts of the brain are involved in the pain response as shown on an MRI?
- A painful stimuli activates the same region of the cortex that is activated by a non painful stimuli in the same place of the skin
- Parts of the insula and cingulate cortex are also activated - they are connected to the limbic system
- Limbic system is known for emotional responses
324
What are some problems with the specificity theory?
- Pain perceived is not always proportional to intensity of stimuli
- Phantom limbs
- Placebo effect
- Modulation by other stimuli
- Referral of pain from viscera to skin
325
Define hyperalgesia
- Increased response to a painful stimulus
| e. g. hypersensitivity in an area that has already been damaged like pricking sunburnt skin
326
Define allodynia
- Painful response to a normal innocuous stimulus
| e. g. touching sunburnt skin
327
What causes hyperglasia?
When skin is damaged inflammatory substances are released which increases sensitivity of nociceptive molecular receptors as the threshold for nociceptors has lowered
328
What is the role of prostaglandins in central sensitisation (pain lecture)?
- Lower the threshold for action potential generation so cause hyperglasia
- Can also cause neurones to become sensitive to non nociceptive inputs - allodynia
329
What is hyperpathia (in pain lecture)?
Axonal loss causing the detection threshold to increase meaning that when it is detected it is very large resulting in an explosive pain
330
What is a phantom limb?
Amputees can feel the limb even though it is not there and can even feel pain in it.
Attempts to block pain do not work
331
What is referred pain?
When damage in the viscera is perceived from coming from an area of the skin depending on what organ is affected
- e.g. pain in left arm when having a heart attack
332
What is procedural memory?
- Skills and associations largely unavailable to conscious mind e.g. motor learning
333
What is declarative memory?
- Available to the conscious mind can be encoded I'm symbols an language
334
What is the duration of the different types memory?
- Immediate memory - few seconds
- Short -term memory - seconds or minutes
- Long-term memory - days, months, years
335
What are the important structures of the brain involved in memory?
- Pre-frontal cortex
- The hippocampus (essential for converting short term memory to long term memory)
- Amygdala (multiple processed sensory inputs)
- Cerebellum (sensorimotor)
336
What can hippocampal lesions lead to?
Memory loss and unable to form new memories
337
Why does synapse strength change?
- They have plasticity
- Facilitation - stronger with stimulus
- Depressions weaker with stimulus
- Ca2+ availably affects its plasticity
338
Define long term potentiation
- The increasing strength of a synapse
339
How is a long term potentiation used to create an association?
The long term potentiation pathway is stimulated at the same time as as a cell producing a strengthen response e.g. pavlovian dogs
340
What is habituation?
The diminishing of an innate response due to a repeated stimulus
341
What is short-term sensitisation?
Repeated gentle stimuli causing habituation
| Response returns after a short period of time
342
What is long-term sensitisation?
Repeated stimuli which causes long term habituation
343
What do long term potentiation, long term depression and short and long term sensitisation require?
- Receptor activation
- Altered synaptic responsivity
- Require protein phosphorylation changes in early stages
- Require protein synthesis for late stages
344
What pathologies affect memory?
- Amnesia
- Head injury, tumour surgery
- Alzheimers
345
What is different about an Alzheimers brain?
- Enlarged temporal horns
- Senile plaques
- Tangles - protein phosphorylation
- Loss of cells
346
What is Kluver-Bucy syndrome?
- Amygdala lesions
| - symptoms: visual agnosia, hyperorality, hypersexuality, hyperphagia
347
What is the Hebbian synapse concept?
Suggests that synapses are actively modifiable (plastic) allowing them to change as new memories form
348
What type of motor neurones are responsible for all movements by skeletal muscles?
Lower motor neurones
349
What is a central pattern generator?
When the spinal cord generates complex behaviours without the input from the brain
350
What is the primary motor cortex?
Gerentes the electrical impulses that cause the contraction of the contralateral body muscles (motor control)
351
What type of motor neurones are responsible for motor function?
Upper motor neurones
352
What is a motor pool?
Where the cell bodies of motor neurones lie
353
How are motor pools organised?
Somatotopically - point of the body corresponds to a specific part of the spinal cord. Motor pool made up of the cell bodies from all the neurones that innervate a particular muscle
354
What do motor cortex upper motor neurones primarily control?
Fine control of more distal structures
355
What do brainstem upper motor neurones primarily control?
Control with postural movement
356
What layer of the cortex are responsible for motor input and motor output?
Input - layer 4 (Internal granula)
| Output - layer 3 (external pyramidal)
357
What are the difference between upper motor neurones of the motor cortex and of the brainstem?
Motor:
- voluntary movements
- Contralaterally - e.g. praises limb movements
Brainstem:
- Maintenance of posture and balance
- Located it several nuclei e.g. reticular formation
358
What s the difference between upper and lower motor neurones?
Upper - always synapse on lower motor neurones
| Lower- always synapse on muscle fibres
359
What is the anticipatory mechanism?
When the body preadjusts its posture in order to compensate for forces generated from another movement
360
What is motor neurone disease?
A degenerative disease of the motor neurones
361
What is the difference between upper and lower motor neurone disease?
```
Lower
- Muscle weakness/paralysis
- Loss of stretch reflexes
- Muscle atrophy
-Usually die from lung dysfunction
Upper
- Muscle weakness
- Spasticity
- Hyperactive reflexes
- Loss of fine voluntary control
usually die from tongue and pharynx involvement
```
362
What is the role of the basal ganglia in movement?
Regulates the function of the upper motor neurones - motor loop
363
What are the basal ganglia composed of?
- Caudate/Putamen (striatum)
| - Globus pallidus
364
How does the basal ganglia initiate movement?
- The striatum activates the Globus Pallidus which inhibits VLo. Inputs from many cortical regions converges on the striatum
- When activated by this the striatum inhibits the Globus Pallidus releasing the VLo to activate and initiate movement
365
What causes Huntington disease?
Due to the degeneration of the striatum and leads to hyperkinesis
366
What causes Parkinson's disease?
Due to the degeneration of the substantial nigra and leads to hypokinesis
367
What is the roll of the cerebellum in movement?
- Detects and corrects differences between intended and actual movement - motor error checking
368
What are the two types of routes for cortical control of lower motor neurones?
- Direct - activation of voluntary movement direct to spinal cord
- Indirect - anticipated by indirect projection via reticular formation to muscles
369
What does EEG stand for?
Electroencephalogram
370
What field potentials are used in an EEG?
20-100microV
371
Does an EEG have good resolution?
- Poor spatial resolution
| - Good temporal resolution
372
What does an MEG do?
Measures the magnetic field evoked by current flow
373
What type of rhythm do relaxed awake individuals with their eyes closed show from an EEG?
Alpha rhythm - 8-13Hz
374
What type of rhythm do aroused awake individuals with their eyes open show from an EEG?
Beta rhythm - 14-25Hz
375
What is gamma rhythm in an EEG?
Normal wake individuals show it with eyes open and shows intermittent bursts of synchronous 30-80Hz in sensory and motor regions
376
Give examples of regional variations in alpha rhythms
Kappa - alpha like in auditory cortex
Nu - alpha like in sensorimotor cortex e.g.. Mirror neurones (electrical activity when watching someones elves movements)
377
What are mirror neurones?
Electrical activity when watching someones elves movements
| Lack of mirror neurones could be related to autism
378
What is theta rhythm in an EEG?
- Early stage sleep
- 4-8Hz
- Found in children and frustrated adults
- Spatial memory tasks
379
What is REM sleep?
Random eye movement sleep - dream sleep
380
What are the stages of non-REM sleep?
Stage 1: alpha rhythm slows, drowsy
Stage 2: sleep spindles, light sleep
Stage 3: Higher amplitude, lower frequency, slowing
Stage 4: delta waves - High amplitude low frequency less than 4Hz, deep sleep - sleep walking can occur in this stage
381
What are the roles of non-REM sleep?
- Restorative
| - Loss evokes homeostatic break down (takes weeks in animals)
382
What animals have REM sleep?
Mammals and young birds
| Reduces with age
383
What is the role of REM sleep?
Laying down of memories
Dream sleep
Deprivation doesn't have much affect, maybe an increase in irritability
384
What parts of the brain are used to control sleep?
- Reticular activating systems (brain stem regions)
- Hypothalamus
- Basal forebrain
- Pineal gland
- Cortex
385
What is the role of the hypothalamus in the control of sleep?
Secretes hypocretin
| Decrease in this compound can lead to narcolepsy
386
What is the role of the pineal gland in the control of sleep?
Secretes melatonin which influences the sleep/wake cycle
- Secretion is affected by light levels
- Serotonin in the day and melatonin at night
387
What are the symptoms of Parkinson's disease?
- Decrease in spontaneous movements
- Gait difficulty
- Postural instability
- tremor
- initiation/termination of movements very difficult
388
What causes Parkinson's disease?
Degeneration of the pigmented neurones in the substance nigra of the brain, resulting in decreased dopamine availability
389
How common is Parkinson's disease?
1-2% of the population
| Increases after age of 60
390
What are the treatments for Parkinson's disease?
- Ca voltage channel blockers - reduces over excitation that causes loss of dopamine producing cells
- Transplantation, stem cells
- Smart stimulators
391
What are the symptoms of Huntington's disease?
- Progressive
- Hyper/dyskinesias
- Akinesia and dystonia
- Dementia
392
What causes Huntington's disease?
- Striato -GPe and striato-gli neurones die followed by more neurodegeneration
- Associated with nuclear and cytoplasmic inclusions containing mutant Huntingtin
- Increase in CAG repeats in Huntingtin gene
393
What are the treatments for Huntington?
- Memantine
- Tetrabenazine
- Deep brain stimulation
- RNA interference
- Stem cell transplantation
394
What are the symptoms of schizophrenia?
- Positive (extra things that experienced)-
hallucinations, delsions
- Negative - Flat affect, alogia, anhedonia (not outgoing)
- Often associated with depression, substance abuse and suicide
395
What are the causes of schizophrenia?
- Increased levels of dopamine
- 50% concordance in momozygotic twins
- substance abuse - cause or effect??
- infection in utero
396
What are the treatments of schizophrenia?
- Antipsychotics
- intense psychotherapy, social support
- Recovery and improvement in symptoms over 50%
397
What are the symptoms of depression?
- Lowered mood
- Anhedonia
- Altered appetite
- Worthlessness and guilt
- Reduced ability of concentration
- Recurrent thoughts of death
398
What are the causes of depression?
- Reduced hippocampal volume
- Genetic serotonin transporter abnormalities
- social affects - poverty, stress, absue
399
What are the treatments of depression?
- Light therapy
- Psychotherapy
- Tricyclic antidepressants
- Prozac
- Exercise
- ECT
400
What are the two types of the stroke?
- Ischaemic stroke (due to embolus clot)
| - Haemorrhagic stroke (entry of blood into CNS via a rupture of a blood vessel)
401
How long does a stroke need to be for there to be irreversible brain damage?
3 hours
402
What are the types of haematomas that affect the brain?
- Epidural (trauma to meningeal artery)
- Subdural (rapid movement of head)
- Subarachnoid (damage to cerebral artery)
403
What is the incidence of stroke?
10% deaths worldwide
404
What are the treatments of stroke?
- Anticoagulant
- Diet /lifestyle
- Thrombolysis - break up clots if given quickly
- Stents
- Surgery
405
What are the types of epilepsy?
Childhood absence epilepsy
- 4-12 years of age
- Mutations in low threshold voltage dependant Ca channels
- Resolves without pathology during puberty
Temporal lobe epilepsy
- late childhood and adolescence
- Most common type of epilepsy in adults
- complex partial seizures often preceded by aura
406
What is the incidence of epilepsy?
0.5-1%
407
What are the causes of epilepsy?
- Reflex seizures - flashing lights
- genetic - mutations in Na+ channels
- alcohol/drugs
- Infection
- 2/3 spontaneously in nature
408
What are the treatments of epilepsy?
```
Acute
- Benzodiazepines
- Recovery position
Chronic
- Pharmacological
- Electrical
- Surgical - removal of tumour
```
409
What are the symptoms of Alzheimers disease?
- Short term memory loss
- Confusion
- Irritability
- Long term memory loss
- Death within 7 years of diagnosis
410
What causes Alzheimers disease?
- age
- Genetic (ApoE4)
- Trauma
- High blood pressure
- Environmental factors
411
What is the incidence of Alzheimers disease?
1.5-2%
412
What are the treatments of Alzheimers disease?
- AChesterase inhibitors
- NMDA receptor antagonists
- Intellectual stimulation
- diet
- not many treatments
413
What part of the brain is used to control eating behaviour?
Hypothalamus
414
What does anabolism mean?
Building up macromolecules for energy storage
415
What does catabolism mean?
Breaking down macromolecules for energy usage
416
What experiments were used to investigated the role of the hypothalamus in eating behaviour?
- A lesion to both sides of hypothalamus causes anorexia
| - If you cut the ventromedial part of the hypothalamus then it causes obesity
417
What is the role of Leptin protein in eating behaviour?
Leptin is released by fat cells in order to decrease eating behaviour
In the absence of leptin, eating behaviour is stimulated
418
What does the binding of Leptin on receptors activate?
- Activates the release of alpha-MSH and CART neurotransmitters
- They send projections to hypothalamus which release TSH and ACTH from the pituitary gland
- TSH and ACTH act on the adrenal glands to increase basal metabolic rate
419
What does the injection of alpha-MSH and CART do?
- Suppresses appetite by mimicking the effect of raised leptin levels
420
What does falling leptin levels stimulate?
Stimulate the release of NPY and AgRP
421
What is the role of NPY and AgRP in eating behaviour?
Stimulated by falling leptin levels
- This inhibits TSH and ACTH
- Stimulate feeding behaviour
- Activates the parasympathetic nervous system
422
What is the role of Gherelin?
Released into bloodstream from an empty stomach and stimulates the role of NPY and AgRP
423
What short term factors affect regulation of feeding?
- Cultural meal times
| - Motivation to continue eating depends on how much you have already eaten
424
What is monogamy?
- One male and female form an exclusive relationship
| - 12% of primates
425
What is polyandry?
- One female mates with many males
| - Rare in mammals
426
What is polygyny?
- One male mates with many females
| - Many mammalian species
427
How does the human brain show sexual dimorphism?
- Males have larger brains than females
- More neurones in the Onuf's nucleus in males
- Pre-optic area of the hypothalamus is larger males
428
How does the menstrual cycle affect behaviour?
- Spatial reasoning tests when oestrogen is lowest
- Sexual encounters increase prior to ovulation
- Sexual attractiveness changes throughout the menstrual cycle
- Synaptic density in hippocampus changes with levels of oestrogen
429
How and why has the use of non-human primates improved neuroscience?
Non human primates - immense knowledge gained on Schizophrenia, Alzheimers and Parkinson's
