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127 Cards in this Set
- Front
- Back
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The vestibular system senses?
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dynamic forces of angular and linear accelerations as well as the static force of gravity NOT VELOCITY
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Vestibular system stimulates compensatory motor reflexes which?
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which maintains body equilibrium, balance, and retinal imagery
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vestibulo-spinal reflexes
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postural adjustments and generation of smooth body movement that keep the body balanced and prevents falling in gravity environment
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vestibulo-occular reflex
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maintains retinal image stability; keeps retinal image fixed as head moving
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If the R and L firing rate is equal, the head is?
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not moving; no motor compensatory reflexes needed
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If R and L firing rates are not equal then CNS registers?
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head movement
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Eye deflection goes toward which firing rate?
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lower firing rate
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Damage to what CN causes loss of balance and inappropriate nystagmus?
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CN 8
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Vertigo
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illusion of movement; you or the world around you is spinning
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If head turns left, eyes turn?
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right by same degree
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Nystagmus can be induced by?
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rotation, visual, or caloric stimulation
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Nystagmus named for direction of what eye movement?
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fast
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Nystagmus is pathological if it?
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occurs spontaneously or is sustained
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Damage to R CN8 vestibular branch results in?
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slow compensatory eye movement to R and very fast return of eye movement; fast movement is nystagmus
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location of cell bodies for CN1 and CN2
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telencephalon
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location of cell bodies for CN3 and CN4
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midbrain
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location of cell bodies for CN5, CN6, CN7, and CN8
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pons
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location of cell bodies for CN9, CN10, CN12
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medulla
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location of cell bodies for CN11
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cervical
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Hair cells release which excitatory neurotransmitter?
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glutamate or aspartate
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Cell body for CN8 located?
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Scarpa's ganglion
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What type of jx found between hair cells?
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tight
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Bending of hair cell towards tall kinocilium causes?
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open tip-link channels that allow K+ to come into cell
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Does a hair cell have an AP?
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NO
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Depolarization of hair cell occurs at which membrane?
Increased transmitter release at which membrane? |
apical membrane; basolateral membrane
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Bending of hair cell away from tall kinocillium causes?
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decreased number of channels; hyperpolarization of hair cell because K+ and Ca++ current decrease
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Perilymph surround?
Contained by? high or low K+? |
surrounds membranous labyrinth; contained by bony labyrinth; low K+
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Endolymph has high or low K+?
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high K+
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Membranous labyrinth made of?
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single sheet of epithelial cells w/ tight jxs
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Perilymph is equivalent to?
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CSF; low K+ and high Na+
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Endolymph contained in?
Secreted by? |
membranous labyrinth; secreted by stria vascularis in scala media
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Overproduction of endolymph causes?
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Meniere's Disease-high fluid pressure w/in membranous labyrinth
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transepithelial voltage; endocochlear potential?
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+80mV
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Transbasolateral membrane voltage?
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-60mV
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Transapical membrane voltage?
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-140mV
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Motion of hair cell stereocilia causes K+ to move along what type of gradient?
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electrical gradient NOT concentration gradient
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Ampulla contains?
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neuroepithelial cells
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Ampulla transduces what type of accelerations?
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angular
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Macula transduces what type of accelerations?
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linear accelerations
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Horizontal semicircular canal sterocilia has tall kinocilium?
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medial
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Ear stones made of?
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CaCO4
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Otolith organs (ear stones) detect what type of forces?
Caused by? |
linear; static displacement of hair bundles due to gravity, and transient displacement of hair bundles due to linear acceleration or deceleration
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X axis
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forward-backward
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Y axis
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left-right
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Z axis
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up-down
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Do angular accelerations affect otolith organs?
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NO; only linear accelerations
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How are hair cells orientated?
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back to back w/ respect to the ridge called the striola
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How is saccule polarized?
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away from the striola
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How is the utricle polarized?
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toward the striola
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Macula in the saccule detects linear changes in what plane?
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vertical plane; upward/downward along Z axis;
example is riding in an elevator |
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Macula in the utricle detects linear changes in what plane?
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horizontal plane; forward and backward along the X azis as well as side to side along the Y axis; example is riding in the car or head tilt
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Semicircular canals are?
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6 areas of neuroepithelium in the membranous labyrinth
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Is ataxia contralateral or ipsilateral?
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always ipsilateral
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Where do deep cerebellar nuclei project to?
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thalamus VA/VL then to frontal cortex
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Do mossy fibers travel in the middle cerebellar peduncle or the inferior cerebellar peduncle?
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middle
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Do climbing fibers travel in the inferior cerebellar peduncle or the middle cerebellar peduncle
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inferior
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What is the inhibitory neurotransmitter released by the purkinje cells onto the deep cerebellar nuclei?
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GABA
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What is the excitatory neurotransmitter released by the mossy fibers and climbing fibers onto the cerebellar cortex?
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glutamate
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Which deep cerebellar nuclei would be active in a piano or violin player?
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emboliform and globose
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Which fibers are the major input to the cerebellum?
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corticopontine fibers
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Corticopontine fibers synapse on ______ nuclei before crossing the midline?
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pontine
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After corticopontine fibers decussate they enter the cerebellum in which peduncle? Innervate the entire cerebellar cortex as what type of fibers?
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middle; mossy
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What two types of fibers are components in the inferior cerebellar peduncle?
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climbing fibers and vestibular fibers
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Can the primary vestibular fiber synapse on the cerebellum directly?
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Yes
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Where is the secondary vestibular fiber from and where does it synapse?
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from pons/medulla; synapses on cerebellum
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What 2 things do the vestibular fibers innervate?
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vermis and vestibulocerebellum
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What is the major output from the cerebellum?
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superior cerebellar peduncle
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How many climbing fibers per purkinje neuron?
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one
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What is the output of cerebellar cortex to deep cerebellar nuclei?
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purkinje cell
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What are the 3 layers of the cerebellar cortex?
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molecular layer, purkinje cell layer, granule cell layer
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Mossy fibers synapse on which cell?
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granule cell
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What is found in the molecular layer of the cerebellar cortex?
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purkinje cell dendrites, granular cell axons (parallel fibers)
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What is found in the purkinje cell layer of the cerebellar cortex?
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purkinje cell bodies (7 million)
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What is found in the granule cell layer?
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granule cells (neurons)
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What are the most numerous neurons in the brain?
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granule cells
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What is the only output cell of the cerebellar cortex?
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purkinje neuron
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If you lesioned the left dentate nucleus what would you see in pt?
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ipsilateral ataxia
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Climbing fibers are afferents from? What do they produce?
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inferior olive nucleus; produce a calcium spike firing pattern in purkinje cells
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What does glutamate released from the climbing fiber do?
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opens VG calcium channels on the purkunje cell
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Do you see spatial or temporal summation with the climbing fiber and purkinje cell?
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spatial
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EPSP generated by the climbing fiber always stimulates what in the purkinje cell?
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complex AP
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With sensory stimulus how do climbing fibers fire and what do they produce?
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fire at low frequency and produce 1-2 complex spikes/sec in purkinje cells
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Parallel fibers (axons of the granule cells) receive afferent information from the?
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mossy fibers from brainstem nuclei and spinal cord
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What type of spike-firing pattern do parallel axons produce in purkinje cells?
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simple spike-firing pattern
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Glutamate released from the parallel fiber opens what channels on the purkinje cell?
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Na+ channels
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What type of summation do you see with parallel fibers and purkinje cells?
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temporal and spatial summation which produce a single AP in a purkinje cell
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What directs the action of parallel fibers on purkinje cells?
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climbing fibers
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What is a form of motor memory?
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climbing fibers can produce LONG-TERM depression in the strength of selected parallel fiber synapses
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What is input specificity?
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ONLY those parallel fiber synapses firing simultaneously with the climbing fibers will show long-term depression
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What is asynergia?
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unregulated movements that are non-functional
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What is the main second messenger that causes LTD?
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calcium
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After learning a task, what happens to the post-synaptic membrane under the parallel fibers?
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depressed
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The thalamus is bounded by?
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anterior and posterior commisures
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What receives massive reciprocal connections back from the cortex?
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relay nuclei in the thalamus
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What is the thalamus part of?
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forebrain - diencephalon
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What is found in the epithalamus?
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parts of pretectum and the pineal body
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What will parallel fiber synapses display following a paired firing of the synapse with a climbing fiber?
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depressed (smaller) EPSP for up to one hr
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Experience causes cerebellar circuits to be?
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modified...this is learning
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Lateral lesions of the cerebellum occur in?
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paramedian or cerebrocerebellum
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Taste sensory input travels to what relay nuclei?
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VPM
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What do you test for in lateral lesions of the cerebellum?
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action or intention tremor, asynergia, dysmetria, dysrhythmia, dysdiadochokinesia
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What is dysmetria?
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pt can't approximate areas of body
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Before learning, how many APs does the purkinje cell fire per second?
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51
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How do you test for truncal ataxia?
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Romberg test - Ask pt to close their eyes and stand still; if they wobble or move, there is a problem
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VPL receives sensory from?
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body
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With the parallel fiber firing, what receptors are stimulated?
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direct and indirect glutamate receptors
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LGN receives sensory input from?
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eyes through the optic tract
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During the motor learning process what happens to the number of complex spikes?
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increases
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The rise in intracelluar ionic calcium in the purkinje cell causes an increase in? Now what?
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protein kinase C; further release of stored calcium for the SR
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Cerebellar lesions cause ataxia on what side of the lesion?
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ipsilateral
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Mamillary bodies are important for?
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memory
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Midline lesions of the cerebellum cause?
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truncal ataxia - unsteady gait, and eye movements abnormalities accompanied by intense vertigo, nausea, and vomiting
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A decrease in APs from the purkinje cells causes _____ of the deep cerebellar nuclei
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disinhibition
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What are the major regulatory functions of the hypothalamus?
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autonomic fx, endocrine fx, homeostasis, and limbic system
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MGN receives sensory input from?
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cochlea
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What does the presynaptic terminal of the parallel fiber release?
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glutamate
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What is dysdiadochokinesia?
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pt unable to perform rapid alternating movements
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The direct (AMPA) channel allows?
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a rise in intracellular Na+ in the purkinje cell which causes further depolarization
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Strong depolarization of the purkinje cell causes?
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VG calcium channels to open
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The indirect (mGluR1) receptor allows?
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a rise in intracellular second messengers IP3 and DAG in the purkinje cell which also causes a rise in calcium and PKC
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What causes long-term depression?
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AP on parallel fiber and AP on climbing fiber occurring simultaneously
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Which fiber fires more frequently during learning?
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climbing
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Sensory from middle ear for balance travels to what relay nuclei?
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VPL
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What happens to the deep cerebellar nuclei with motor learning?
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disinhibition
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Lateral lesions of the cerebellum cause?
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appendicular ataxia - unsteady limb movement
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How many APs are fired per second with the combined firing for the purkinje cells?
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51
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VPM receives sensory input from?
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head
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