Theme 1 - Neuroscience & The Brain Flashcards
What are the 3 different locations of chemical synapses?
axodendritic
axosomatic
axoaxonic
What 2 types of response can be generated by a receptor upon recognition of a neuroreceptor?
- Direct excitatory or inhibitory neurotransmission
- Neuromodulation
Define neuromodulation?
alters the presynaptic cell’s ability to release more transmitter or the postsynaptic cell’s ability to respond
During brain development, from where do neuroectoderm cells receive their induction signals?
Notochord
During brain development, the neural plate folds to form what?
Neural tube
Label day 24 of brain development. (4)
Neural crest cells
Mantle layer
Ependymal layer
Lumen
In terms of neural tube defects, what condition is the failure of the anterior neuropore to close?
Anencephaly
In terms of neural tube defects, what condition is the failure of the posterior neural tube to close?
Spina bifida
What does the forebrain develop from?
Prosencephalon
What does the midbrain develop from?
Mesencephalon
What does the hindbrain develop from?
Rhombencephalon
What are the primary vesicles? 3
Prosencephalon
Mesencephalon
Rhombencephalon
What are the secondary vesicles and what do they become? 5
Telencephalon - Cerebral hemispheres Optic vesicles - eyes Diencephalon - Thalamus/hypothalamus Metencephalon - Pons/cerebellum Myelencephalon - Medulla
What’s grey and white matter made from?
Grey - neuronal cell bodies
White - myelenated axons
What are the 4 lobes of the cerebral hemispheres?
Frontal
Temporal
Occipital
Parietal
What feature divides the frontal and parietal lobes?
Central sulcus
What features lie either side of the central sulcus?
Precentral gyrus - motor
Postcentral gyrus - ssensory
What feature divides the parietal and temporal lobes?
Lateral lobes
Label the following areas of the cortex (5)
Prefrontal Primary motor Somatosensory Visual Motor speech area of Broca
What is the name of the white matter tract linking the two cerebral hemispheres?
Corpus callosum
What brain system is associated with emotions and memory?
Limbic system
What deep brain structure is associated with posture and movement?
Basal ganglia
What are the main components of the limbic system?
Cingulate cortex Fornix Hypothalamus Mamillary bodies Amygdala Hippocampus
What two structures are connected by the fornix?
Mamillary bodies
Hippocampus
What structures make up the basal ganglia?
Lentiform nucleus
Caudate nucleus
Label the caudate and lentiform nucleus on slide 20 lecture 2
Slide 20 lecture 2
What structures does the hypothalamus lie between?
Mamillary bodies and optic chiasm
What senses are the superior and inferior colliculi associated with?
Superior - vision
Inferior - auditory
What is the function of the pons?
Relay information to the cerebellum
Label features of medulla oblongata 4
Pyramid
Olive
Cuneate tubercle
Gracile tubercle
Afferent from/to?
To brain/spinal cord
Efferent from to?
From brain to effector organ
What is a ganglion?
Group of neural cell bodies outside the CNS
Characteristics and example of motor ganglion
Autonomic
Smaller neurons
Parasympathetic ganglion
Characteristics and example of sensory ganglion
Larger neurons
Dorsal root ganglion
Label the directions of the human prefrontal cortex
Rostral
Cortex
Dorsal
Dorsal
What is the purpose of myelin sheathing of a neuron?
Increase conduction velocity
What are the 3 classifications of neurons?
multipolar
bipolar
unipolar
How many axons do neurons have?
1
Where are pyramidal and Purkinje cell neurons found?
Neocortex
cerebellum
An example of where Pseudo-unipolar neurons found?
Dorsal root ganglion
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
In terms of signalling what term is used when multiple inputs influence a single neuron and give an example
Convergent
Retina
In what nervous system do inter neurons occur and are they motor or sensory?
CNS
Neither, they process signals
4 features of glia
No action potentials
Do not form synapses
Able to divide
From myelin sheaths
What is the ratio of glia to neurons?
10-50:1
Purpose and site of oligodendrite
production / maintenance of myelin sheath
CNS
Purpose and site of astrocyte
Support
Development
Protection from harmful substances
CNS
Purpose and site of microglia
immune cells, protect neurons from disease, migrate to injury sites, engulf microbes / debris, mesodermal origin CNS
Purpose and site of ependymal cells
line brain’s ventricles and central canal of spinal cord,
form CSF
CNS
Purpose and site of Schwann cells
production / maintenance of
myelin sheath
PNS
Purpose and site of satellite cells
support neurons, regulate exchange of materials between neurons and interstitial fluid
PNS
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
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)
5 features of electrical synapses
faster bidirectional smaller gap no plasticity no ampliafication
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
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
Label action potential graph
Resting state -70mV Threshold -55mV Depolarisation until +40mV Repolarisation Hyperpolarisation Refactory period
What channels keep the neuron at resting potential?
Inward rectifier K+ channels
What channels does initial depolarisation open?
Na+ channels
How is depolarisation a positive feedback loop?
Na+ going into the cell causes more depolarisation
At what point during depolarisation does overshoot occur?
Vm above 0mV
What two channels are involved in repolarisation?
Na+ channels become inactivated
Delayed rectifier K+ channels open (so more K+ goes out)
At what voltage do inward rectifier channels open?
below -60mV
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
In what 2 ways can neurons code for the intensity of synaptic input?
Firing frequency
Different neurons for different strength stimuli
What term describes how easy it is to start nervous signalling (overall, in sensory and muscle?
Excitability
Sensitivity
Irritability
How does lidocaine work? 3
Blocks sodium ion channels
Raises theshold
Lowers excitability
What type of drug is cabamazepine and how does it work?
Anticonvulsant
blocks sodium channels and reduces excitability
Equilibrium potentials for Na, K, Ca, Cl
Na +50
K -90
Na +123
Cl -40/-65 in neurons
5 characteristics of action potentials
Stereotyped Short duration A spike Always the same - all or none Require time to start
5 characteristics of graded potentials
*Decrease as they move along* Electrically localised Last a long time much Flatter in shape Are conducted almost instantly
What is the term that describes when an action potential jumps from node to node?
Saltatory conduction
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
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
Where are the pool of synaptic vesicles located and what are they anchored by?
Cytoskeleton
synapsin
How does Ca2+ release the vesicles from the cytoskeleton?
Ca2+ activates CaMKII which phosphorelates synapsin
What complex docks vesicles to the plasma membrane?
SNARE
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
Via what process are vesicles recoverd
Endocytosis
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
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
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
What type of gradient powers vesicular membrane and plasma membrane transporters?
vesicular - protein
plasma - electrochemical
4 categories of neurotransmitters
Amino acids
monoamines
acetylcholine
neuropeptides
3 characteristics of monoamine, acetylcholine and neuropeptides.
Synthesized locally in presynaptic terminal
Stored in synaptic vesicles
Released in response to local increase in Ca2+
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
Will a low frequency stimulation and localised increase in Ca2+ result in small molecule neurotransmitter or neuropeptide?
Small molecule neurotransmitter
What is the difference between the vesicles that smallmolecule transmitter and neuropeptide are stored in?
Small molecule - small clear vesicles
Neuropeptide - large dense vesicles
What is the excitatory neurotransmitter in the CNS?
glutamate
2 inhibitory neurotransmitters in the CNS and thir specific location.
GABA - brain
Glycine - spinal cord and brain stem
From what two sources is glutamate synthesised from?
from glucose via the Krebs cycle
from glutamine converted by glutaminase into Glutamate
What loads and stores glutamate into vesicles?
VGLUTs
What facilitates the reuptake of glutamate?
excitatory amino acid transporters (EAATs
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
From what id GABA synthesised?
synthesized from glutamate (Glu)
in a reaction catalyzed by
glutamic acid decarboxylase (GAD)
What loads and stores GABA and glycine into vesicles?
vesicular GABA transporter, GAT
What facilitates the reuptake of GABA?
transporters on glia and neurons including non-GABAergic neurons
What will too much Glu / too little GABA result in?
hyper-excitability – epilepsy excitotoxicity
What will too much GABA result in?
sedation coma
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
Two subcategories of monamines and an example of each
Catecholamines - dopamine, adrenaline
Indolamines - serotonin
5 steps of Catecholamine synthesis
Tyrosine (L-dopa) Dopamine Norepinephrine Epinephrine
What is L dopa used to treat?
Parkinson’s
What are Catecholamine’s loaded and stored in vesicles by?
Vesicular monoamine transporters (VMATs)
What facilitates the reuptake of catecholaines?
reuptake into the axon terminal by transporters powered by electrochemical gradient (Dopamine transporters (DATs), Norepinephine transporters (NETs) etc.)
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)
How do amphetamines affect catecholamines?
reverses transporter so pumps out transmitter and blocks reuptake (DA & NE)
How does cocaine and ritalin affect catecholamines?
(Ritalin) block DA reuptake into terminals. More DA in synaptic cleft – extended action on postsynaptic neuron.
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-stagePD,depression anddementia).
How does entacapone affect catecholamines?
COMT inhibitor
treatment of PD
What is the chemical orogin of seretonin?
thyptophan
How is serotonin stored, uptaken and destroyed?
Stored in vesicles
reuptaken by transporters on presynaptic membrane
destroyed by MAOs
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
What packs Ach into vesicles?
vesicular acetylcholine transporter (VAChT).
Where is Ach degraded and by what?
in synaptic cleft by acetylcholinesterase (AChE)
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)
Which type of receptors are responsible for fast and slow transmission respectively?
Ionotrophic - fast
Metabotropic - slow
What is a ligand gated ion channel and how does it work?
An ionotrophic receptor
Neurotransmitter binds
central pore opens
ions flux through
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)
What are the three types of ionotrophic receptor that respond to glutamate?
NMDA
AMPA
Kainate
Two characteristics of Non-NMDA receptors (AMPA and Kainate)?
Fast opening channels permeable to Na+ and K+
Responsible for early phase EPSP
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
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.
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
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)
Draw how the three G protein subunits interect following the binding of a ligand
lecture 7 slide 26
What is the shortcut pathway?
receptor to G-protein to ion channel
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).
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.
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
7 types of metabotrophic receptors
GABA(B) receptor
muscarinic acetylcholine receptors
dopamine receptors
noradrenergic and adrenergic receptors
serotonin receptors
neuropeptide receptors
metabotropic glutamate receptors
Draw modal model of memory
Stimulus Sensory (attention) Short term - rehearsal (encoding/retrieval) Long term
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
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
What is the lesion localisation for short-term memory patients?
Left hemisphere
Usually affecting the parietal and temporal lobes
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
What actively refreshes the contents of the phonological store?
Articulatory loop
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
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
What is the study/test vs study/study experiment evidence of?
Retrieval practice effect
What is transfer appropriate processing?
A “shallow” processing task might be better if retrieval uses the same type of processing
What is amnesia?
Ability to take in new information is severely and usually permanently affected. Intelligence and personality intact.
What effect does amnesia have upon Verbal and visual short-term memory?
Nothing, it remains intact
What type of amnesia comes after the brain injury and what types of memory are affected?
Anterograde
episodic memories are severely affected
Draw the divisions of long term memory
Declarative - Episodic (events) Semantic (facts)
Implicit - Priming effects Procedural memory
What is the dedicated system for procedural memory and inn what type of patients is procedural memory effected?
Basal ganglia
Huntington’s
What type f amnesia affects memories before brain injury?
Retrograde amnesia although to what extent episodic memories are affected is highly contested.
What is the Standard Model on consolidation?
Over time, declarative memories become consolidated to other brain regions
What does semantic dementia refer to?
A poor knowledge of meaning of words or concepts
What region of the brain is associated with semantic knowledge?
lateral temporal cortex on the LEFT side of the brain
What is confabulation?
erroneous memories, either false in themselves or resulting from ‘true’ memories misplaced in context an inappropriately retrieved or interpreted
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
Spontaneous confabulation may result from damage to what region of the brain?
Usually a result of frontal lobe damage
What does and EEG measure?
synchronous fields in pyramidal cells
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
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
4 behavioural criteria of sleep
Reduced motor activity
Decreased response to stimulation
Stereotypic postures
Relatively easy reversibility
What are the three function states of sleep?
Awake
Non REM I,II,III,IV
REM sleep
4 possible functions of sleep/dreaming?
Conservation of metabolic energy
Cognition
Thermoregulation
Neural maturation and mental health
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
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.
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
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
What separates the lateral ventricles?
Septum pellucidum
What sits on the roof, lateral wall and floor of the lateral ventricles?
Corpus callossum
Caudate nucleus
Hippocampus
What connects the lateral and third ventricle?
Foramen of Monro
What does the third ventricle sit between and what forms it’s roof?
Thalami
Fornix
Label slide 12 of the ventricular system
Caudate nucleus corpus callossum Septum pellucidum Fornix Thalamus Lentiform nucleus Hippocampus
What connects the third and fourth ventricle?
cerebral aqueduct
- Also called Aqueduct of Sylvius
What surrounds the cerebral aqueduct/ Aqueduct of Sylvius?
Midbrain
What surrounds the fourth ventricle?
- Cerebellum posterior
- Pons and medulla anterior
- Cerebellar peduncles lateral
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
What produces CSF and where is it?
Choroid plexus
lining of ventricles
Outline the basic structure of the choroid plexus
Fenestrated capillaries - filter
Cuboidal epithelium - transport
What barrier is formed by the cuboidal epithelium?
Blood-CSF barrier
What is the percentage breakdown of CSF by location?
60% vebtricles
40% Other sites in the brain
What must CSF pressure exceed and why?
Venous pressure
Otherwise tips of villi close off to prevent reflux of blood into subarachnoid space
What is the total and produced daily volume of CSF?
140ml
500ml per day
4 functions of CSF
- Hydraulic buffer to cushion brain against trauma
- Vehicle for removal of metabolites from CNS
- Stable ionic environment for neuronal function
(communicates with brain interstitial fluid via pia) - Transport of neurotransmitters and chemicals
What does yellow or cloudy CSF indicate?
Yellow (Xanthocromia) E.g. Subarachnoid haemorrhage Coudy e.g. MS Bacterial meningitis
From where is a lumbar puncture taken?
At lumbar cistern
L3/4 in children
L4/5 in adults
What is hydrocephalus and 3 possible causes?
Dilation of brain ventricles
blocked CSF circulation
, impaired absorption
, or over secretion
What is non-communicating hydrocephalus and how is it treated?
Blockage within the ventricular system
Surgery to insert shunt
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
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
What are the two main families of GABA receptor?
GABA(a) ionotropic
GABA(b) metabotropic
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 synapticTwo examples of GABAa agonist/antagonist and where do these bind to?
Muscimol - agonist
Bicuculline - antagonist
They bind to GABA binding site
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
Example of a benzodiazapine and 5 effects
Diazepam (Valium) reduce anxiety cause sedation reduce convulsions relax muscles cause amnesia
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.
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)
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
What are the 3 subdivisions of the dopaminergic system and what are they associated with?
Nigrostriatal - motor control (parkinsons)
Mesolimbic
Mesocortical - behaviour
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
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
What is the result of dysfunction of the mesolimbic and mesocortical system?
Mesolimbic - addiction
Mesocortical - Schizophrenia
Where is serotonin produced?
Raphei Nuclei in brainstem
Where is noradrenaline produced and what type of receptors does it affect?
Locus Coeruleus
metabotrophic
4 disorders of the cholinergic system
Myasinthnia gravis
Alzheimers
Addiction
Epilepsy
Two characteristics of coma
Characterised by complete loss of wakefulness and reactivity
A state of unresponsiveness to external stimuli with eyes closed
5 causes of coma
Sedation / anaesthesia Epilepsy Electrolyte / metabolic disturbance Disturbance of thermoregulation Structural damage to brainstem / thalamus / cortex
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
Timeline for types of vegetative state
Continuing - 4 weeks
Permanent - non-trauma 6 months
- trauma 1 year
4 Non progressive causes of dementia
Head injury
Stroke
encephalitis
meningitis
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.
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
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
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
Other than a huge cranium in infants what is the likely consequence of hydrocephaly?
Herniation
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
4 types of haemorrhage
Extradural/epidural haemorrhage
Subdural haemorrhage
Subarachnoid haemorrhage
Intracerebral haemorrhage
Other than haemorrhage, 3 other types of space occupying lesions.
Ischaemic infarct with subsequent oedema or haemorrhage
Neoplasm
Abscess
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
Two types of cerebral oedema
Vasogenic Increased vascular permeability
Cytotoxic Neuronal, glial or endothelial cell damage
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)
4 types of infection associated with the CNS
Meningitis
Encephalitis
Abscess
Localised
How does the body discriminate types of mechanical sensation?
It uses different types of sensor
5 types of mechanosensory receptors
Shear - Meissner corpuscle Contact - Merkel disc Tension/folding - Ruffini corpuscle procking - bare nerve endings Pressure/vibration - Pacinian corpuscle
3 mechanisms of sensory stimulus discrimination
Different types of sensor for the same modality
Spacial distribution of sensors
Windows of response intensity (hot/cold)
What are the motor neurons in the spinal cord known as which can generate a motor response independent of the brain?
Lower motor neurons
What type of neurons are the final common path for all neuronal information from the CNS to the skeletal muscles?
Lower motor neurons
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
What are the two proprioceptive sensory organs and what do they regulate?
muscle spindles - length
golgi tendon - tension
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
What vest describes the type of neural phenomenon whereby connections that are active together become stronger?
Hebbian connection
2 rules of synaptic modification
Neurons that fire together wire together
Neurons that fore out of synch lose their link
What mechanism underlies synaptic strengthening?
Long Term Potentiation
Three characteristics of LTP
Temporal
Associative
Specific
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
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.
What is a neuroblast?
Postmitotic, immature nerve cell that will differentiate into a neuron
Example of chemoattractant and chemorepellent
Netrin
Slit
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
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
Where does adult neurogenesis occur
Subventricular zone to olfactory bulb
Hippocampus
Why does alcohol affect memory in terms of receptors?
It is an NMDA antagonist therefore prevents LTP
What is Korsakoff syndrome?
loss of recent memory, and tendency to fabricate accounts of recent events (confabulation).
Memory related side affect of benzodiazapines?
anterograde amnesia
What is the hierarchial order order of the 5 sensory systems
Association cortex Secondary sensory cortex Primary sensory cortex Thalmic relay nuclei Receptors
What are the three main multimodal association areas and what do they process?
Posterior - language/perception
Temporal - emotion and memory
Prefrontal - executive functions
What is the Wada procedure used for?
To determine which hemisphere is dominant for speech
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
What is prosopagnosia?
Difficulty recognising faces
What is visual agnosia?
Inability to recognise objects
What is anosognosia?
inability to recognise own illness
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
In terms of brain activity at onset what are the 2 types seizure?
Global
Focal/partial
5 types of idiopathic (primary) generalised seizures
tonic-clonic seizures (“grand mal”) absences (“petit mal”) tonic seizures atonic seizures myoclonic seizures
3 features if idiopathic primary generalise seizures
onset in childhood or adolescence
usually no focal symptoms/signs
often a number of seizure types cluster
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
3 phases of tonic clonic seizures
tonic - continous muscle spasm
clonic - jerking that slows
post-ictal - coma, drowsiness, muscle pain
do pts get a warning of a tonic clonic (grand mal seizure)?
No
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
2 types of partial/focal onset seizures?
simple partial seizure - aware aura
complex partial seizure - some awareness aura
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
a partial seizure most often relates to which lobe of the brain?
Temporal
Brain structure most commonly related to epilepsy?
Hippocampus
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)
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
3 features of frontal lobe epilepsy
brief 10-30 seconds
rapid recovery, frequent
predominantly nocturnal
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
4 features of occiptal lobe epliepsy
typically simple visual hallucinations -balls of coloured or flashing lights
amaurosis (blackout or whiteout) at onset -25%
