Neurophysiology Flashcards
What are the two broad types of memory and what do they include?
Explicit:
- episodic
- semantic
Implicit:
- tactile
Working memory, what areas are included?
Central Executive: dorsolateral prefrontal cortex
Visual Sketch pad: Non dominant parieto-occipital lobe
Phonological store: dominant perisylvian areas and inner ear
What important circuit is involved in episodic memory and what does it consist off?
Circuit of Papez:
Mallilary bodies, anterior thalamus, cingulate gyrus, hipocampus
What circuits make up the Mesocorticolimbic pathway?
Mesolimbic pathway:
Ventral Tegmentum Area to the nucleus accumbens
Mesocortical pathway:
VTA to the cortex
Where is dopamine released from?
Substania nigra pars compacta
What are the types of ways neurons can increase signal intensity?
Spatial Summation:
- increasing the number of fibres activated
Temporal summation:
- increase rate of action potential firing
Where is CFS produced and what type of epithelium does it?
Choroid plexuses within the lateral and third ventricles.
Ependymal cells - cubodial epithelium
What enzyme breaks down the catecholamines, including dopamine?
Monoamine Oxidase
What amino acid does dopamine derive from and what is its precursor before being fully formed?
L-Tyrosine
L-DOPA
What is serotonin’s precursor?
Tryptophan
What is included in the monoamines?
- ACh
- Catecholamines (dopamine, noradrenaline and adrenaline)
- serotonin
- histamine
What are the reaction that occur during the triple response?
Red line - dilation
flare - Axon response
Wheal - dilation around due to histamine
What is a specific biomarker only found in CFS that can be used for diagnostic purposes?
Beta - 2 - transferrin
What is a motor unit?
A single somatic lower motor neuron and all the muscle fibres it innervates
What sized diameter does neurons supplying smooth muscle have?
Small diameter
What muscle is used to test the blowing out of cheeks?
Orbicularis Oris.
*note it is a missconception that it is the buccinator. Actually to carry out this movement requires the tightening of the lips which the orbicularis oris achieves.
Outwith motor function of the facial muscles, what other functions does the facial nerve have?
Sensory taste to anterior 2/3rd of tongue
autonomic:
- secretion of saliva from sublingual and submandibular
- lacrimal glands = tear formation
What nerve innervates the parotid gland?
Glosopharngeal
What cells carry out mylination in the CNS?
Oligodendrocytes
How do motor neurons differ from sensory neurons?
- they are always mylinated
- transmission from CNS to PNS
- multipolar
- cell body within grey mater
What is the steps involved in pupillary light reflex?
Optic tract to midbrain.
Pretectum to Edinger Westphal nuceli - which contains parasympathetic fibres of Crn III
To cililary ganglion for post ganglionic fibres which innervate pupillary constriction
What is consensual light reflex?
Where the pupil constricts when the light is shone into the other eye
Where is oxytoncin made?
Hypothalamus
Compression of the spinal cord to cause loss of sensation below the umbilicus would suggest what level has been injured?
T10
The lateral corticospinal tract is responsible for which kind of movement?
Skilled voluntary movement
Which tract carries pressure sensation?
Spinothalamic
What area in the brain is concerned with co-ordination of speech?
Broca’s area. - frontal lobe
Damage gives aphasia
What area allows for comprehension of speech?
Wernicke’s area - supra-posterior temporal lobe
usually on the left
A stroke that causes aphasia has affected which artery?
Middle cerebral
What are the endogenous opioids?
Enkephalins
Proopiomelanocortin (POMC)
Dynorphins
What are the opioid receptors?
Mu
Kappa
Delta
What are the families of dopamine and what do they contain? and their action?
D1 Family:
d1 and d5 receptors.
Stimulatroy G - proteins that increase cAMP levels
D2 Family:
d2,3,4 receptors.
Inhibitory G proteins - decrease cAMP levels.
Where is the principle site of noradrenaline production in the brain?
Locus Coeruleus
In attention and alertness what role does dopamine play?
Enhancement of signals - namely from the mesocortical pathway
Improves attention
more cognitive and behaviour appropriateness to task
In attention and alertness what role does noradrenaline play?
Increases the ability to remain focused
Reduces noise of other stimuli
Inhibitory of other sensory stimuli
What are the otolith organs and what is their functions?
Utricle - detects acceleration, deceleration
Saccule - Sensing which way the body is up and falling motion
Which nuclei and which part are assoiciated with the vestibular occular reflex?
medial Vestibuli nuclei
What are the main receptors for glutamate?
NMDA
AMPA
What mediates Sematic memory?
Basal ganglia and other sub-cortical structures
What mediates episodic memory?
Mainly by the hippocampus
In the dorsal lemincus pathway, there is media branches that come off into the grey matter, what do they do?
Involved in spinal reflexes
Gate theory
Spinocerebellar tracts
What does Kinesthesia mean?
awareness of one’s body in space through the sensory organs - via proprioception
What is the cerebral perfusion equation?
Cerebral perfusion = MAP - ICP
Does the CFS contain red blood cells?
No.
What are important functions of the superior colliculi?
They are the origin of the tectospinal pathway - which predominantly synapse in the scalene muscles of the neck - allowing response to visual stimuli
Contain pre-tectal nuclei - important for pupillary light reflex
important area for projecting from the lateral geniculate to the occulomotor nuclei
Where do the meninges derive from?
Mesoderm
What is the Arcuate Nucleus?
Store of dopamine important for the Tuber-infunidubal system
What are the two major types of voluntary movements?
Ballistic movement - based on pre-programmed motor functions. little room for adjustment. Fast acting
Pursuit movements: Constantly updated by sensory information, allows for accuracy and adjustment. Slow acting
What area is predominantly activated when practising a movement in you’re head?
Supplementary motor area
What are the main functions of the basal ganglia?
and what mainly feeds into it?
and where is its primary output?
initiation of the movement and supressing other movements
Planning complex movements
Mainly fed by the pre-frontal cortex
and output is to the pre-motor cortex
What are the main functions of the cerebellum?
and what is its main input?
and whats its main output?
co-ordination and smooth execution of movements
learning of movements and error detection
Main input is the primary somatosensory cortex
Output is primary motor cortex
What is the meaning of Kinathesia?
Awareness to the limbs of:
- movement
- speed of movement
- direction of movement
*it is essentially the movement of limb awareness
What are the most important receptors for proprioception?
Joint receptors
cutaneous receptors
Golgi tendon organs
muscle spindles
What are the four main mechanoreceptors in the skin and what is the adaptation rates?
Meissner’s Corpuscles - Rapid adapting
Pacinan Corpuscle - Rapid adapting
Merkel Corpuscle - Slowly adapting
Ruffini endings - Slowing adapting
What ascending pathway do the mechanoreceptors use?
Dorsal leminicus
What is another name for the spinothalamic tract?
Antro-lateral tract
What type of fibres are cold fibres? and are the rapidly adapting or slow adapting
A delta - Slowly adapting
What is the pathway for discriminative touch? especially two point discrimination.
Dorsal lemniscus pathway
What transmits non-discriminative touch, innocuous thermal and nociceptive sensations?
spinothalmic pathway
With repeated noxious stimuli what can occur to the nerves and what is this clinically called?
Sensitization - where the nerves become easier to fire off - probably due to inflammatory meditators.
Hyperalgesia
What factors make up the blood barrier?
Tight junctions of the epithelial cells
Reduced expression of receptors for substances - thus fewer things are allowed to pass by pinocytosis or endocytosis
Pericytes - forming strong seal around
Astrocyte foot projections circulating the vessels
When controlling muscle contraction force, what mechanisms are used?
Summation - adding together of individual twitches to make the intensity of the muscle contraction increase.
achieved by:
- multiple fibre summation - size principle (small diameter neurons first)
- frequency summation - increased action potentials leading to tetanization
During the Jaw Jerk reflex - what is the pathways and why is tested?
Afferent pathway via V3 of trigeminal.
slightly opened mouth is tapped on chin, afferent rely back to motor nuclei of trigeminal sending signals to the masseter muscle to protrude chine up
What is resting membrane of a neuron potential?
-65mV
How does the sympathetic system stimulate the adrenal medulla? and what does it predominantly release?
The adrenal medulla is essentially the ganglion of the sympathetic nervous system.
Pre-ganglionic symapthetic nerve fibres stimulate via the release of ACh binding to nicotonic receptors on the chromoafin cells (as if they were ganglions).
this promotes the release of noradrenaline and adrenaline
What are sweat glands acted upon by?
They are acted upon by post ganglionic symapthetic fibres which are unique in that they react to ACh
How do photoreceptors respond to light?
Become hyperpolarised
the decomposition of rhodospin causes release of phosphodiestarase which reduces cGMP levels causing Na2+ to stop entering the cell and as a result hyperpolarises
What kind of receptor is GABA?
G protein
How is muscle contraction intiatial increased?
increased temporal summation followed by spatial summation
Which pain fibres have a high threshold?
A Delta
What is the main Ion associated with pain?
H+
note the question is ion not neurotransmitter
Which motor area is most responsible for sequencing events?
Pre-motor area
What is the cerebellar vermis main function?
Posture maintenance and head position
What two features lead to cogwheel spascicity?
Rigidity and tremor
How many rami are there?
124 (62 either side)
What is the filum terminalis?
Thickened pia mater at the conus medullaris
Which area in the brain recieves dual blood supply and what are the vessels?
Primary visual cortex.
Middle and posterior cerebral
What is mullers muscle?
Smooth muscle associated with keeping the eyelid open. supplied by sympathetic activation.
assocaited with horner’s syndrome.
Define attention:
A global cognitive process encompassing multiple sensory modalities operating over multiple sensory domains
Domain specific Attention: can also be domain specific if needed - to a particular sensory input such as visual
How can attention be sub-dived?
Arousal - state of wakefulness
Vigilance - maintaining attention over a period of time
Divided attention - Responding to more than one task at hand
Selective attention - blocking out other sensory stimuli and remaining focused to one task
What makes up the Ascending reticular activating system?
Brain stem nuclei
Thalamic nuclei
Cortex nuclei
Which hemisphere is the visual sketch pad found?
Non - dominant
Semantic memory is stored in the temporal lobes, what is the order of information in there?
Ventral = visual
Dorsal lateral = non visual
Anterior = complex Posterior = non complex
How do you test semantic memory?
General knowledge questions
fluency - name as many animals
naming objects
What is curare?
ACh antagonist
Where is the action potential started on the axon?
Axon Hillock
What are two forces influencing movement of
ions across membranes?
Electrical gradient
Concentration gradient
What is the membrane equilibrium potential?
what equation can be used to calculate this?
The charge at which the electrical gradient and concentration gradient are balancing each other out, resulting in no net movement of ions.
nernst equation
What are the figures for Na2+ and K+ levels intra cellularly and extracellularly?
Na2+ = 145: 12
K+= 5: 150
What brings back the normal membrane potential after action potential?
Na2+/ K+ ATPase
Define reflex and give an example
Involuntary sterotyped reaction to stimulus
Tendon jerk
How does spatial summation influence action potentials?
increases the graded summation to cause action potentials
What is it called when one neuron sends a signal which transmits to multiple neurons?
Divergence
What is it called when collection of neurons collective group towards one neuron, and give an example of when this is active?
Convergence
used in memory when various stimuli can lead to the same neuron firing for that particular memory
How does the myelin shealth increase conductivity?
reduces loss of current out the cell and allows for saltatory conduciton
What is the term in which the sum of multiple electrical stimulus can result in action potential arriving?
and what is the opposite of this?
Excitatory postsynpatic potential
