Theme 1 - Neuroscience & The Brain Flashcards
1
Q
What are the 3 different locations of chemical synapses?
A
axodendritic
axosomatic
axoaxonic
2
Q
What 2 types of response can be generated by a receptor upon recognition of a neuroreceptor?
A
- Direct excitatory or inhibitory neurotransmission
- Neuromodulation
3
Q
Define neuromodulation?
A
alters the presynaptic cell’s ability to release more transmitter or the postsynaptic cell’s ability to respond
4
Q
During brain development, from where do neuroectoderm cells receive their induction signals?
A
Notochord
5
Q
During brain development, the neural plate folds to form what?
A
Neural tube
6
Q
Label day 24 of brain development. (4)
A
Neural crest cells
Mantle layer
Ependymal layer
Lumen
7
Q
In terms of neural tube defects, what condition is the failure of the anterior neuropore to close?
A
Anencephaly
8
Q
In terms of neural tube defects, what condition is the failure of the posterior neural tube to close?
A
Spina bifida
9
Q
What does the forebrain develop from?
A
Prosencephalon
10
Q
What does the midbrain develop from?
A
Mesencephalon
11
Q
What does the hindbrain develop from?
A
Rhombencephalon
12
Q
What are the primary vesicles? 3
A
Prosencephalon
Mesencephalon
Rhombencephalon
13
Q
What are the secondary vesicles and what do they become? 5
A
Telencephalon - Cerebral hemispheres Optic vesicles - eyes Diencephalon - Thalamus/hypothalamus Metencephalon - Pons/cerebellum Myelencephalon - Medulla
14
Q
What’s grey and white matter made from?
A
Grey - neuronal cell bodies
White - myelenated axons
15
Q
What are the 4 lobes of the cerebral hemispheres?
A
Frontal
Temporal
Occipital
Parietal
16
Q
What feature divides the frontal and parietal lobes?
A
Central sulcus
17
Q
What features lie either side of the central sulcus?
A
Precentral gyrus - motor
Postcentral gyrus - ssensory
18
Q
What feature divides the parietal and temporal lobes?
A
Lateral lobes
19
Q
Label the following areas of the cortex (5)
A
Prefrontal Primary motor Somatosensory Visual Motor speech area of Broca
20
Q
What is the name of the white matter tract linking the two cerebral hemispheres?
A
Corpus callosum
21
Q
What brain system is associated with emotions and memory?
A
Limbic system
22
Q
What deep brain structure is associated with posture and movement?
A
Basal ganglia
23
Q
What are the main components of the limbic system?
A
Cingulate cortex Fornix Hypothalamus Mamillary bodies Amygdala Hippocampus
24
Q
What two structures are connected by the fornix?
A
Mamillary bodies
Hippocampus
25
What structures make up the basal ganglia?
Lentiform nucleus
| Caudate nucleus
26
Label the caudate and lentiform nucleus on slide 20 lecture 2
Slide 20 lecture 2
27
What structures does the hypothalamus lie between?
Mamillary bodies and optic chiasm
28
What senses are the superior and inferior colliculi associated with?
Superior - vision
| Inferior - auditory
29
What is the function of the pons?
Relay information to the cerebellum
30
Label features of medulla oblongata 4
Pyramid
Olive
Cuneate tubercle
Gracile tubercle
31
Afferent from/to?
To brain/spinal cord
32
Efferent from to?
From brain to effector organ
33
What is a ganglion?
Group of neural cell bodies outside the CNS
34
Characteristics and example of motor ganglion
Autonomic
Smaller neurons
Parasympathetic ganglion
35
Characteristics and example of sensory ganglion
Larger neurons
| Dorsal root ganglion
36
Label the directions of the human prefrontal cortex
Rostral
Cortex
Dorsal
Dorsal
37
What is the purpose of myelin sheathing of a neuron?
Increase conduction velocity
38
What are the 3 classifications of neurons?
multipolar
bipolar
unipolar
39
How many axons do neurons have?
1
40
Where are pyramidal and Purkinje cell neurons found?
Neocortex
| cerebellum
41
An example of where Pseudo-unipolar neurons found?
Dorsal root ganglion
42
In terms of signalling what term is used when a single neuron sends its output signal to many neurons and give an example
Divergent
| Skin
43
In terms of signalling what term is used when multiple inputs influence a single neuron and give an example
Convergent
| Retina
44
In what nervous system do inter neurons occur and are they motor or sensory?
CNS
| Neither, they process signals
45
4 features of glia
No action potentials
Do not form synapses
Able to divide
From myelin sheaths
46
What is the ratio of glia to neurons?
10-50:1
47
Purpose and site of oligodendrite
production / maintenance of myelin sheath
| CNS
48
Purpose and site of astrocyte
Support
Development
Protection from harmful substances
CNS
49
Purpose and site of microglia
```
immune cells, protect
neurons from disease, migrate
to injury sites, engulf microbes
/ debris, mesodermal origin
CNS
```
50
Purpose and site of ependymal cells
line brain’s ventricles and central canal of spinal cord,
form CSF
CNS
51
Purpose and site of Schwann cells
production / maintenance of
myelin sheath
PNS
52
Purpose and site of satellite cells
support neurons, regulate exchange of materials between neurons and interstitial fluid
PNS
53
What is a glioma and 4 characteristics that give them such a shit prognosis.
```
largest group of primary tumours
derived from glial cells
• usually highly malignant
• grow rapidly
• difficult to remove completely with surgery
• Usually inside cranium
```
54
What is a neuroblastoma and 4 characteristics
```
Tumor
most common in children & infants
outside cranium
derived from neural crest cells from sympathetic NS
increased Catecholamine levels (often)
```
55
5 features of electrical synapses
```
faster
bidirectional
smaller gap
no plasticity
no ampliafication
```
56
What is A neuron determines whether to fire based on the “add together” of all the tiny signals it is receiving from several other neurons synapsing on it (from both excitatory and inhibitory inputs). In this way small depolarisations (if there are many) can reach threshold known as?
Spacial summation
57
What is When the input neuron is firing fast enough so that the receiving neuron can “add together” the many tiny signals, ultimately reaching threshold known as?
Temporal summation
58
Label action potential graph
```
Resting state -70mV
Threshold -55mV
Depolarisation until +40mV
Repolarisation
Hyperpolarisation
Refactory period
```
59
What channels keep the neuron at resting potential?
Inward rectifier K+ channels
60
What channels does initial depolarisation open?
Na+ channels
61
How is depolarisation a positive feedback loop?
Na+ going into the cell causes more depolarisation
62
At what point during depolarisation does overshoot occur?
Vm above 0mV
63
What two channels are involved in repolarisation?
Na+ channels become inactivated
| Delayed rectifier K+ channels open (so more K+ goes out)
64
At what voltage do inward rectifier channels open?
below -60mV
65
Why does after-hyperpolarisation occur in terms of channels open/shut/activated?
The delayed rectifier channels are slow to close.
| At the same time the inward rectifiers open and Na+ are inactivated
66
In what 2 ways can neurons code for the intensity of synaptic input?
Firing frequency
| Different neurons for different strength stimuli
67
What term describes how easy it is to start nervous signalling (overall, in sensory and muscle?
Excitability
Sensitivity
Irritability
68
How does lidocaine work? 3
Blocks sodium ion channels
Raises theshold
Lowers excitability
69
What type of drug is cabamazepine and how does it work?
Anticonvulsant
| blocks sodium channels and reduces excitability
70
Equilibrium potentials for Na, K, Ca, Cl
Na +50
K -90
Na +123
Cl -40/-65 in neurons
71
5 characteristics of action potentials
```
Stereotyped
Short duration
A spike
Always the same - all or none
Require time to start
```
72
5 characteristics of graded potentials
```
*Decrease as they move along*
Electrically localised
Last a long time
much Flatter in shape
Are conducted almost instantly
```
73
What is the term that describes when an action potential jumps from node to node?
Saltatory conduction
74
Give the 5 steps of a typical chemical synapse transmission from the transmitter being synthesized and stored in vesicles to the transmitter being released into the synaptic cleft.
Action potential invades the presynaptic terminal
Depolarisation causes opening of voltage gated Ca2+ channels
Influx of Ca2+
Ca2+ causes vesicles to fuse with pre-synaptic membrane
Transmitter released into presynaptic cleft via exoxytosis
75
Give 5 steps of a typical chemical synapse transmission from when the transmitter is released into the cleft through to retrieval of vesicular membrane
Transmitter binds to receptor molecules in post synaptic cleft
Opening/closing of post synaptic vesicles
Post synaptic current causes excitation/inhibition potential that changes excitability of post synaptic cell
Removal of transmitter by glia/enzyme
Retrieval of vesicular membrane
76
Where are the pool of synaptic vesicles located and what are they anchored by?
Cytoskeleton
| synapsin
77
How does Ca2+ release the vesicles from the cytoskeleton?
Ca2+ activates CaMKII which phosphorelates synapsin
78
What complex docks vesicles to the plasma membrane?
SNARE
79
Give the 4 steps of exocytosis during neurotransmitter release.
Vesicle docks
SNARE complexes pull membranes together
Entering Ca2+ binds to synaptotagmin
Synaptotagmin the catalyses membrane fusion
80
Via what process are vesicles recoverd
Endocytosis
81
How does Botulinum affect the synaptic terminal?
Affect SNARE and dont allow the vesicle to fuse
Acts directly on the neuromuscular junction to inhibit release of Ach. Muscles have no input so become permanently relaxed
82
How does tetanus afect he synaptic terminal?
Affect snare and don't allow the vesicle to fuse
Acts upon the interneurons in the spinal cord.
Inhibits the release Gly and GABA st inhibitory neurons so muscles become permanently contracted
83
5 examples of ways in which diseases can affect the presynaptic terminal?
```
Impair vesicle recycling - myasynthenic
Vesicle fusion - latrotoxin
Bind to SNARE - BoTX/TeTX
Impair transynaptic sugnalling
Attack presynaptic Ca2+ channels - LEMS
```
84
What type of gradient powers vesicular membrane and plasma membrane transporters?
vesicular - protein
| plasma - electrochemical
85
4 categories of neurotransmitters
Amino acids
monoamines
acetylcholine
neuropeptides
86
3 characteristics of monoamine, acetylcholine and neuropeptides.
Synthesized locally in presynaptic terminal
Stored in synaptic vesicles
Released in response to local increase in Ca2+
87
3 characteristics of neuropeptides
Synthesized in the cell soma and transported to the terminal
Stored in secretory granules
Released in response to global increase in Ca2
88
Will a low frequency stimulation and localised increase in Ca2+ result in small molecule neurotransmitter or neuropeptide?
Small molecule neurotransmitter
89
What is the difference between the vesicles that smallmolecule transmitter and neuropeptide are stored in?
Small molecule - small clear vesicles
| Neuropeptide - large dense vesicles
90
What is the excitatory neurotransmitter in the CNS?
glutamate
91
2 inhibitory neurotransmitters in the CNS and thir specific location.
GABA - brain
| Glycine - spinal cord and brain stem
92
From what two sources is glutamate synthesised from?
from glucose via the Krebs cycle
| from glutamine converted by glutaminase into Glutamate
93
What loads and stores glutamate into vesicles?
VGLUTs
94
What facilitates the reuptake of glutamate?
excitatory amino acid transporters (EAATs
95
What role do glia play in the reuptake of glutamate?
glial cells convert Glu to glutamine and this is transported from the glia (“ball boys”) back to nerve terminals where it is converted back into Glutamate
96
From what id GABA synthesised?
synthesized from glutamate (Glu)
in a reaction catalyzed by
glutamic acid decarboxylase (GAD)
97
What loads and stores GABA and glycine into vesicles?
vesicular GABA transporter, GAT
98
What facilitates the reuptake of GABA?
transporters on glia and neurons including non-GABAergic neurons
99
What will too much Glu / too little GABA result in?
hyper-excitability – epilepsy excitotoxicity
100
What will too much GABA result in?
sedation coma
101
Mechanism of action of GHB?
a GABA metabolite that can be converted back to GABA
Increases amount of available GABA
too much leads to unconsciousness and coma
102
Two subcategories of monamines and an example of each
Catecholamines - dopamine, adrenaline
| Indolamines - serotonin
103
5 steps of Catecholamine synthesis
```
Tyrosine
(L-dopa)
Dopamine
Norepinephrine
Epinephrine
```
104
What is L dopa used to treat?
Parkinson's
105
What are Catecholamine's loaded and stored in vesicles by?
Vesicular monoamine transporters (VMATs)
106
What facilitates the reuptake of catecholaines?
reuptake into the axon terminal by transporters powered by electrochemical gradient (Dopamine transporters (DATs), Norepinephine transporters (NETs) etc.)
107
What 3 things can happens to catechloamines once they are back in the cytoplasm?
- reloaded back into vesicles
- enzymatically degraded by Monoamine oxidases (MAOs)
or
- inactivated by Catechol-O-methyl-transferase (COMT)
108
How do amphetamines affect catecholamines?
reverses transporter so pumps out transmitter and blocks reuptake (DA & NE)
109
How does cocaine and ritalin affect catecholamines?
(Ritalin) block DA reuptake into terminals. More DA in synaptic cleft – extended action on postsynaptic neuron.
110
How does selegiline affect catecholamines?
MAO inhibitor found in dopaminergic nerve terminals thus preventing the degradation of DA allowing more to be released on subsequent activations
( treatment of early-stage PD, depression and dementia).
111
How does entacapone affect catecholamines?
COMT inhibitor
| treatment of PD
112
What is the chemical orogin of seretonin?
thyptophan
113
How is serotonin stored, uptaken and destroyed?
Stored in vesicles
reuptaken by transporters on presynaptic membrane
destroyed by MAOs
114
3 drugs that affect serotonin and how
Fluoxetine (Prozac) blocks reuptake of serotonin (SSRI – selective serotonin reuptake inhibitor)
Fenfluramine stimulates the release of serotonin and inhibits its reuptake
MDMA, methylenedioxymethamphetamine (ecstasy) causes NE and serotonin transporters to run backwards releasing neurotransmitter into synapse/extracellular space
115
What packs Ach into vesicles?
vesicular acetylcholine transporter (VAChT).
116
Where is Ach degraded and by what?
```
in synaptic cleft
by acetylcholinesterase (AChE)
```
117
What drugs affect Ach and how?
AChE (Acetylcholinesterase) inhibitors
block the breakdown of ACh, prolonging its actions in the synaptic cleft
e.g. Neostigmine (treatment of myasthenia gravis, MG)
118
Which type of receptors are responsible for fast and slow transmission respectively?
Ionotrophic - fast
| Metabotropic - slow
119
What is a ligand gated ion channel and how does it work?
An ionotrophic receptor
Neurotransmitter binds
central pore opens
ions flux through
120
What type of ions do glutamate and GABA ionotrophic receptors flux and what is the effect?
Glutamate ionotropic receptors in general flux Na+, which causes an EPSP (Excitatory Post Synaptic Potential)
GABA ionotropic receptors flux Cl-, which causes an IPSP (Inhibitory Post Synaptic Potential)
121
What are the three types of ionotrophic receptor that respond to glutamate?
NMDA
AMPA
Kainate
122
Two characteristics of Non-NMDA receptors (AMPA and Kainate)?
Fast opening channels permeable to Na+ and K+
| Responsible for early phase EPSP
123
Characteristics of NDMA receptor?
Slow opening channel – permeable to Ca2+ as well as Na+ and K+
BUT also
2) requires an extracellular glycine as a cofactor to open the channel
3) it is also gated by membrane voltage – Mg2+ ion plugs pore at resting
membrane potentials. When membrane depolarizes Mg2+ ejected from
channel by electrostatic repulsion allowing conductance of the other
cations, activity-dependent synaptic modification.
NMDA receptors responsible for a late phase EPSP
Activated only in an already depolarized membrane in the presence of glutamate
124
What does PCP (angel dust) affect?
NMDA receptors also inhibited by phencyclidine (PCP, angel dust) and MK801; both bind in the open pore.
Blockade of NMDA receptors in this way produces symptoms that resemble the hallucinations associated with Schizophrenia.
125
6 ionotrophic receptors and what effect they have
Glutamate - excitatory
GABA(A) - inhibitory (brain)
Glycine - inhibitory (spinal cord and brain stem)
Nicotine - excitatory at NMJ (neuromuscular junction)
- excitatory or modulatory in the CNS
Serotonin -excitatory or modulatory
ATP - excitatory
126
How do metabotrophic receptors work?
They transduce signals into the cell not directly through an ion channel but through activation of a G-protein which in turn triggers a series of intracellular events (that can lead to ion channel opening)
G-protein coupled receptors (GPCRs)
127
Draw how the three G protein subunits interect following the binding of a ligand
lecture 7 slide 26
128
What is the shortcut pathway?
receptor to G-protein to ion channel
129
How do G protein receptors influence the synthesis of the second messenger cAMP?
Gs and Gi have opposite effects on adenylyl cyclase, thus stimulating or inhibiting the synthesis of cAMP and the subsequent activation of protein kinase A (PKA).
130
4 steps of the second messenger PIP2 cascade?
Gq activates phospholipase C (PLC)
which converts PIP2 into IP3 and diacylglycerol (DAG).
DAG activates protein kinase C (PKC) and IP3 releases Ca2+ from internal stores which activates Ca2+-dependent enzymes.
131
How can the amount of neurotransmitter that is released be modulated by the presynaptic receptors??
autoreceptors - regulate release of transmitter by modulating its synthesis, storage, release or reuptake
heteroreceptors - (axoaxonic synapses or extrasynaptic)
regulate synthesis and/or release of transmitters other than their own ligand
132
7 types of metabotrophic receptors
GABA(B) receptor
muscarinic acetylcholine receptors
dopamine receptors
noradrenergic and adrenergic receptors
serotonin receptors
neuropeptide receptors
metabotropic glutamate receptors
133
Draw modal model of memory
```
Stimulus
Sensory
(attention)
Short term - rehearsal
(encoding/retrieval)
Long term
```
134
What is the evidence for the dual sketchpad model of memory?
Visula-spacial sketchpad - - Central execuitive - - Phonological store
Dual test showed that numbers could be remembered whilst reasoning applied
135
What is then evidence for the phonological store? 3
Greater error rate in remembering words that are phonologically similar as well as syllables and how quick the word is to say
But semantic similarity has no effect on error rate
136
What is the lesion localisation for short-term memory patients?
Left hemisphere
| Usually affecting the parietal and temporal lobes
137
What are the two subdivisions of the visuospatial sketchpad and what do these store?
Visual cache - form and colour
| Inner scribe - spacial and movement and can rehearse visual cache
138
What actively refreshes the contents of the phonological store?
Articulatory loop
139
What is the evidence for the visuospatial sketch pad?
Subject performs a visual task and a spacial task. Each task is run with visual interference and spatial interference. If the interference is the same then they do shit
140
What are the three types of processing, how deep is it and what is the retention like?
Orthographic - Shallow - Poor
Phonological - Medium - Average
Semantic - Deep - Good
141
What is the study/test vs study/study experiment evidence of?
Retrieval practice effect
142
What is transfer appropriate processing?
A “shallow” processing task might be better if retrieval uses the same type of processing
143
What is amnesia?
Ability to take in new information is severely and usually permanently affected. Intelligence and personality intact.
144
What effect does amnesia have upon Verbal and visual short-term memory?
Nothing, it remains intact
145
What type of amnesia comes after the brain injury and what types of memory are affected?
Anterograde
| episodic memories are severely affected
146
Draw the divisions of long term memory
Declarative - Episodic (events) Semantic (facts)
| Implicit - Priming effects Procedural memory
147
What is the dedicated system for procedural memory and inn what type of patients is procedural memory effected?
Basal ganglia
| Huntington's
148
What type f amnesia affects memories before brain injury?
Retrograde amnesia although to what extent episodic memories are affected is highly contested.
149
What is the Standard Model on consolidation?
Over time, declarative memories become consolidated to other brain regions
150
What does semantic dementia refer to?
A poor knowledge of meaning of words or concepts
151
What region of the brain is associated with semantic knowledge?
lateral temporal cortex on the LEFT side of the brain
152
What is confabulation?
erroneous memories, either false in themselves or resulting from ‘true’ memories misplaced in context an inappropriately retrieved or interpreted
153
What is the difference between provoked and spontaneous confabulation?
Provoked - a normal response to a demand for information which is not available
Spontaneous – the person acts on their erroneous memories
154
Spontaneous confabulation may result from damage to what region of the brain?
Usually a result of frontal lobe damage
155
What does and EEG measure?
synchronous fields in pyramidal cells
156
What are the 4 basic EEG phenomena and when do these occur?
Alpha - awake with eyes closed
Beta - awake eyes open
Theta - drowsiness/sleep/pathology
Delta - drowsiness/sleep/pathology
157
In what two ways can synchronous rhythms be generated in the brain?
Led by pacemaker thalmic cell
| Or the timing arises from the collective behaviour of the neurons themselves
158
4 behavioural criteria of sleep
Reduced motor activity
Decreased response to stimulation
Stereotypic postures
Relatively easy reversibility
159
What are the three function states of sleep?
Awake
Non REM I,II,III,IV
REM sleep
160
4 possible functions of sleep/dreaming?
Conservation of metabolic energy
Cognition
Thermoregulation
Neural maturation and mental health
161
What is the difference between PET and fMRI in terms of what they measure?
PET measures change of blood flow to a region.
fMRI is sensitive to the concentration of oxygen in the blood.
Therefore an indirect measure of neuron activity
162
What is BOLD fMRI?
BOLD signal: blood oxygen-level –dependent contrast, is the signal measured in fMRI that relates to the concentration of oxy- and deoxyhaemoglobin in the blood.
163
How does MRI work?
Protons initially aligned randomly
magnetic field causes come of them to align
Pass radiowave through them causes them to spin 90 degrees
This spinning causes a resonance that can be measures
164
Draw and label the 4 components of the lateral ventricles and state what lobe they are located in.
Anterior horn - frontal
Body - parietal
Posterior horn - occiptal
Inferior horn - temporal
165
What separates the lateral ventricles?
Septum pellucidum
166
What sits on the roof, lateral wall and floor of the lateral ventricles?
Corpus callossum
Caudate nucleus
Hippocampus
167
What connects the lateral and third ventricle?
Foramen of Monro
168
What does the third ventricle sit between and what forms it's roof?
Thalami
| Fornix
169
Label slide 12 of the ventricular system
```
Caudate nucleus
corpus callossum
Septum pellucidum
Fornix
Thalamus
Lentiform nucleus
Hippocampus
```
170
What connects the third and fourth ventricle?
cerebral aqueduct
| - Also called Aqueduct of Sylvius
171
What surrounds the cerebral aqueduct/ Aqueduct of Sylvius?
Midbrain
172
What surrounds the fourth ventricle?
- Cerebellum posterior
- Pons and medulla anterior
- Cerebellar peduncles lateral
173
The fourth ventricle has 3 foramen, what are these nad what do they drain into?
Two Foramen of Luschka (lateral)
One Foramen of Magendie (middle)
- Into Cisterna Magna
174
What produces CSF and where is it?
Choroid plexus
| lining of ventricles
175
Outline the basic structure of the choroid plexus
Fenestrated capillaries - filter
| Cuboidal epithelium - transport
176
What barrier is formed by the cuboidal epithelium?
Blood-CSF barrier
177
What is the percentage breakdown of CSF by location?
60% vebtricles
| 40% Other sites in the brain
178
What must CSF pressure exceed and why?
Venous pressure
| Otherwise tips of villi close off to prevent reflux of blood into subarachnoid space
179
What is the total and produced daily volume of CSF?
140ml
| 500ml per day
180
4 functions of CSF
1. Hydraulic buffer to cushion brain against trauma
2. Vehicle for removal of metabolites from CNS
3. Stable ionic environment for neuronal function
(communicates with brain interstitial fluid via pia)
4. Transport of neurotransmitters and chemicals
181
What does yellow or cloudy CSF indicate?
```
Yellow (Xanthocromia)
E.g. Subarachnoid haemorrhage
Coudy
e.g. MS
Bacterial meningitis
```
182
From where is a lumbar puncture taken?
At lumbar cistern
L3/4 in children
L4/5 in adults
183
What is hydrocephalus and 3 possible causes?
Dilation of brain ventricles
blocked CSF circulation
, impaired absorption
, or over secretion
184
What is non-communicating hydrocephalus and how is it treated?
Blockage within the ventricular system
| Surgery to insert shunt
185
What is Dandy Walker syndrome?
Congenital malformation of the cerebellum
Caused by obstruction in the foramina of the fourth ventricle
In infancy child's head may become enlarged
186
What is communicating hydrocephalus and 3 possible causes?
Obstruction in the arachnoid villi
Movement of CSF into venous sinuses is impeded
- E.g. Impaired absorption following subarachnoid haemorrhage, trauma or bacterial meningitis
187
What are the two main families of GABA receptor?
GABA(a) ionotropic
| GABA(b) metabotropic
188
What are the differences between GABA(a) and GABA(b) receptors?
```
a - ionotropic
Ligand gated Cl-
fast
mainly GABAergic
b - metabotropic
G protein coupled receptors
indirectly coupled to K or Ca channel
Slow
pre and post synaptic
```
189
Two examples of GABAa agonist/antagonist and where do these bind to?
Muscimol - agonist
Bicuculline - antagonist
They bind to GABA binding site
190
Three examples of indirect GABAa agonists
Benzodiazepine - Increases receptor affinity for GABA so channel opens more frequently
Barbiturates - increase duration of channel openings
Alcohol - agonist
191
Example of a benzodiazapine and 5 effects
```
Diazepam (Valium)
reduce anxiety
cause sedation
reduce convulsions
relax muscles
cause amnesia
```
192
What happens of you combine alcohol and Valuim?
Valium is a benzodiazapine and so increases the effectiveness of the receptor. Alcohol also acts as an indirect agonist> the effects are therefore additive and can be fatal.
193
Give an example of a GABAb receptor agonist and its use?
Baclofen
| used as a muscle relaxant to reduce spasticity e.g. in Huntington’s disease)
194
What are the 6 diffuse modulatory systems?
```
(Specific populations of neurons that project diffusely and modulate the activity of Glutamate and GABA neurons in their target areas.)
Dopaminergic (DA)
Serotonergic (5-HT)
Noradrenergic (NA/NE)
Adrenergic
Cholinergic (ACh)
Histaminergic
```
195
What are the 3 subdivisions of the dopaminergic system and what are they associated with?
Nigrostriatal - motor control (parkinsons)
Mesolimbic
Mesocortical - behaviour
196
What are the subtypes of dopamine receptors and what are the differneces?
D1 & D2
both metabotropic
D1 - excitatory - stimulate adenyl cyclase
D2 Inhibitory - Inhibit adenyl cyclase
197
What 2 diseases result from dysfunction of the nigrostriatal system and what is the diffference?
Parkinson’s disease
destruction of DA projections from SN to basal ganglia
Huntington’s disease
destruction of DA target neurons in striatum
198
What is the result of dysfunction of the mesolimbic and mesocortical system?
Mesolimbic - addiction
| Mesocortical - Schizophrenia
199
Where is serotonin produced?
Raphei Nuclei in brainstem
200
Where is noradrenaline produced and what type of receptors does it affect?
Locus Coeruleus
| metabotrophic
201
4 disorders of the cholinergic system
Myasinthnia gravis
Alzheimers
Addiction
Epilepsy
202
Two characteristics of coma
Characterised by complete loss of wakefulness and reactivity
A state of unresponsiveness to external stimuli with eyes closed
203
5 causes of coma
```
Sedation / anaesthesia
Epilepsy
Electrolyte / metabolic disturbance
Disturbance of thermoregulation
Structural damage to brainstem / thalamus / cortex
```
204
What is the difference between a coma, vegetative state and minimally conscious state
C - Absent wakefulness absent awareness
VS - Wakefulness absent awareness
MCS - Wakefulness minimal awareness
205
Timeline for types of vegetative state
Continuing - 4 weeks
Permanent - non-trauma 6 months
- trauma 1 year
206
4 Non progressive causes of dementia
Head injury
Stroke
encephalitis
meningitis
207
5 causes of dementia that are apparently progressive but non damaging to the brain
```
systemic disease (metabolic, endocrine),
prescribed drugs,
psychiatric illness,
poor sleep,
chronic pain, etc.
```
208
6 causes of dementia that are damaging to the brain but not neurodegenerative
```
cerebrovascular disease (vascular dementia),
MS,
alcohol,
brain tumours or hydrocephalus,
HIV,
B12 deficiency
```
209
5 neurodegenerative diseases
Alzheimer’s disease,
dementia with Lewy bodies
(DLB, LBD — closely related to Parkinson’s);
also fronto-temporal lobar degeneration spectrum, Huntington’s,
Creutzfeldt-Jakob (prion) disease
210
What is the threshold for raised intercranial pressure and what are 3 possible causes?
Above 200mm H2O
Increased CSF volume (hydrocephalus)
Intracranial space occupying lesion (neoplasm, haemorrhage, abscess)
Cerebral oedema
211
Other than a huge cranium in infants what is the likely consequence of hydrocephaly?
Herniation
212
Three types of herniation, whats the worst one and why?
Subfalcial (cingulate)
Central/transtentorial
Tonsillar/cerebellar - the worst
Because can compress medulla and impair respiratory/cardiac functions
213
4 types of haemorrhage
Extradural/epidural haemorrhage
Subdural haemorrhage
Subarachnoid haemorrhage
Intracerebral haemorrhage
214
Other than haemorrhage, 3 other types of space occupying lesions.
Ischaemic infarct with subsequent oedema or haemorrhage
Neoplasm
Abscess
215
```
What type of vessel is injured in each of these vascular injuries?
Extradural
Subdural
Subarachnoid
Interperenchymal
```
Extra - artery (MMA)
Sub - vein
Subarachnoid - berry aneurysm circle of willis
Inter - hypertension capillary
216
Two types of cerebral oedema
Vasogenic Increased vascular permeability
| Cytotoxic Neuronal, glial or endothelial cell damage
217
7 types of neural neoplasms
Gliomas (astrocytoma, oligodendroglioma, glioblastoma)
Neural tumours (ganglion cell tumours)
Meningiomas
Poorly differentiated neoplasms (medulloblastoma)
Primary CNS lymphoma
Metastasis (lung, breast, skin/melanoma, kidney, GI tract)
Peripheral nerve tumours (schwanoma, neurofibroma, MPNST)
218
4 types of infection associated with the CNS
Meningitis
Encephalitis
Abscess
Localised
219
How does the body discriminate types of mechanical sensation?
It uses different types of sensor
220
5 types of mechanosensory receptors
```
Shear - Meissner corpuscle
Contact - Merkel disc
Tension/folding - Ruffini corpuscle
procking - bare nerve endings
Pressure/vibration - Pacinian corpuscle
```
221
3 mechanisms of sensory stimulus discrimination
Different types of sensor for the same modality
Spacial distribution of sensors
Windows of response intensity (hot/cold)
222
What are the motor neurons in the spinal cord known as which can generate a motor response independent of the brain?
Lower motor neurons
223
What type of neurons are the final common path for all neuronal information from the CNS to the skeletal muscles?
Lower motor neurons
224
What will destruction of a SINGLE ventral root or spinal nerve result in and why?
Paresis
Lower motor neurons arranged in columns
Each column extends through more than one segment of cord.
Each muscle receives input from more than one ventral root or spinal cord
225
What are the two proprioceptive sensory organs and what do they regulate?
muscle spindles - length
| golgi tendon - tension
226
How does that arrangement of tendon organs differ from that of muscle spindles?
tendon organs arranged in series so detect the tension from contraction
spindles in parallel so detect passive stretch
227
What vest describes the type of neural phenomenon whereby connections that are active together become stronger?
Hebbian connection
228
2 rules of synaptic modification
Neurons that fire together wire together
| Neurons that fore out of synch lose their link
229
What mechanism underlies synaptic strengthening?
Long Term Potentiation
230
Three characteristics of LTP
Temporal
Associative
Specific
231
Two characteristics of Neural Stem cells / Neural precursor cells?
Infinitely self –renewing
After terminal division and differentiation they can give rise to the full range of cell classes within the relevant tissue
232
Two characteristics of Neural progenitor cell?
```
Incapable of continuing self – renewal
Capable to give rise to only one class of differentiated progeny, e.g. an oligodendroglial progenitor cell will give rise to oligodendrocytes until its mitotic capacity is exhausted.
```
233
What is a neuroblast?
Postmitotic, immature nerve cell that will differentiate into a neuron
234
Example of chemoattractant and chemorepellent
Netrin
| Slit
235
What is the critical period concept and two important factors for its completion
A variable time window for different skills and behaviours.
Availability of appropriate influences (e.g. exposure to language, or species-specific songs for songbirds)
Neural capacity to respond to them
236
Difference between PNS and CNS in terms of regeneration.
Schwann cells in PNS aid in regeneration.
| Does not happen in CNS, results in glial scar
237
Where does adult neurogenesis occur
Subventricular zone to olfactory bulb
| Hippocampus
238
Why does alcohol affect memory in terms of receptors?
It is an NMDA antagonist therefore prevents LTP
239
What is Korsakoff syndrome?
loss of recent memory, and tendency to fabricate accounts of recent events (confabulation).
240
Memory related side affect of benzodiazapines?
anterograde amnesia
241
What is the hierarchial order order of the 5 sensory systems
```
Association cortex
Secondary sensory cortex
Primary sensory cortex
Thalmic relay nuclei
Receptors
```
242
What are the three main multimodal association areas and what do they process?
Posterior - language/perception
Temporal - emotion and memory
Prefrontal - executive functions
243
What is the Wada procedure used for?
To determine which hemisphere is dominant for speech
244
What is the difference between Broca's and Wernicke's aphasia?
Broca's - difficulty in speaking. non fluent but comprehends
| Wernicke's - fluent but without comprehension
245
What is prosopagnosia?
Difficulty recognising faces
246
What is visual agnosia?
Inability to recognise objects
247
What is anosognosia?
inability to recognise own illness
248
What is the difference between agnosia, apraxia and aphagia i terms of disorder?
Agnosia - disorder of high level sensory function
Apraxia - disorder of high level motor ccordination
Aphagia - disorder of communicating/symbols
249
In terms of brain activity at onset what are the 2 types seizure?
Global
| Focal/partial
250
5 types of idiopathic (primary) generalised seizures
```
tonic-clonic seizures (“grand mal”)
absences (“petit mal”)
tonic seizures
atonic seizures
myoclonic seizures
```
251
3 features if idiopathic primary generalise seizures
onset in childhood or adolescence
usually no focal symptoms/signs
often a number of seizure types cluster
252
6 features of juvenile myoclonic epilepsy
commonest form of primary generalized epilepsy
juvenile onset, probably lifelong
early morning myoclonic jerks (ask)
photosensitive, sleep deprivation triggers
+/- absences
generalized tonic clonic seizures occur without warning
253
3 phases of tonic clonic seizures
tonic - continous muscle spasm
clonic - jerking that slows
post-ictal - coma, drowsiness, muscle pain
254
do pts get a warning of a tonic clonic (grand mal seizure)?
No
255
6 features of absences (petit mal)?
abrupt
short, 5-20 seconds
multiple times/day, can lead to learning difficulties
unresponsive, amnesia for the gap, rapid recovery
tone preserved (or mildly reduced)
eyelid flickering
256
2 types of partial/focal onset seizures?
simple partial seizure - aware aura
| complex partial seizure - some awareness aura
257
6 features of secondary generalise tonic/clonic seizures
warning/aura –eg epigastric rising sensation, altered smell, déjà vu, fear
cannot abort attack
onset sudden
duration 1-3 minutes
then falls , loses consciousness as seizure generalizes
rigidity/ convulsive jerks/ excess salivation
incontinence/tongue bite common
red/blue, wakes in ambulance/A&E
258
a partial seizure most often relates to which lobe of the brain?
Temporal
259
Brain structure most commonly related to epilepsy?
Hippocampus
260
6 physical symptoms of temporal lobe epilepsy?
hallucination of taste, speech and /or smell, visual distortion
epigastric rising sensation (over humpback bridge)
pallor / flushing / heart rate changes (can mimic panic/hyperventilation attacks)
automatisms- semi-purposeful movements
oral- lip smacking, chewing movements
dystonic posturing (limb rises)
261
4 cognitive/affective symptoms of temporal lobe epilepsy?
déjà vu / jamais vu
speech arrest (dominant hemisphere)
formed words during the seizure implies non-dominant hemisphere focus
affective
fear, elation, depression, anger
262
3 features of frontal lobe epilepsy
brief 10-30 seconds
rapid recovery, frequent
predominantly nocturnal
263
4 features of parietal lobe epilepsy
positive sensory symptoms (unlike TIA/stroke)
tingling, pain
distortion of body shape/image
Jacksonian march of positive sensory symptoms
264
4 features of occiptal lobe epliepsy
typically simple visual hallucinations -balls of coloured or flashing lights
amaurosis (blackout or whiteout) at onset -25%
