Motor systems Flashcards

1
Q

what type of movements are the motor cortex and spinal cord respectively involved in?

A

motor cortex: complex movement
spinal cord: pre-generated/reflex movements

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2
Q

which 2 structures does the motor cortex interacted with the most (feedback AND feedforward)

A

basal ganglia and cerebellum

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3
Q

what lobe is involved in action? What are the rostral and caudal regions of the lobe involved in?

A

frontal lobe
rostral: abstract goal
caudal: specific action

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4
Q

motor cortex areas from posterior to anterior

A

primary motor cortex M1 (area 4), supplemental motor area SMA and lateral premotor cortex (Area 6), and pre-supplemental motor area

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5
Q

what brain region is affected by parkinson’s disease?

A

basal ganglia

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6
Q

what do lesions to M1 and premotor / SMA respectively cause?

A

M1: contralateral paralysis & spasticity
premotor / SMA: affects organization & movement control

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7
Q

give an example of what happens when SMA and premotor cortex are lesioned respectively

A

SMA: alien limb, loss of spontaneous behavior
premotor cortex: loss of ability to use sensory info to reach for objects

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8
Q

what do primary motor and primary somatic sensory cortexes have in common?

A

same somatotopic map

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9
Q

what mediates sensory-motor transformations? & what is their role

A

reciprocal connections between parietal lobe and premotor cortex.
enables sensory info to guide interactions with objects in the environment

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10
Q

specifically what brain regions are involved in arm movements toward objects?

A

dorsal premotor cortex, primary motor cortex, parietal lobe

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11
Q

map used to guide goal-directed movements that decide what neuron responds to what type of stimuli (touch or visual) in receptive field. where are the neurons located?

A

peripersonal spatial map; parietal and premotor cortex

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12
Q

what neurons are involved in planning movement? what is the function more precisely and when do they fire?

A

premotor neurons: connect sensory input to the appropriate action; fires in preparation AND during movement of ipsi or contralateral arm

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13
Q

primary motor cortex neurons fire only when the ________ arm moves

A

contralateral

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14
Q

which brain areas are involved in shaping the hand to grab something?

A

parietal lobe, ventral premotor cortex, primary motor cortex

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15
Q

what do mirror neurons respond to? where are they located

A

respond to their’s or other’s goal-oriented movements (grabbing object, but not object alone); in premotor cortex

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16
Q

what is the SMA involved in?

A

internally generated movement, planning of complex movement, conscious action, specific movement sequences, thinking/imagining learned movement

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17
Q

signal in SMA neurons that shows up 1 sec before voluntary movement

A

readiness potential

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18
Q

the primary motor cortex accounts for how much of cortical motor output to the brainstem/spinal cord? where does the rest come from

A

1/3
premotor, SMA, S1 primary somatosensory cortex

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19
Q

name the 2 tracts we talked about and what regions they connect

A

corticospinal tract: motor cortex to spinal cord (direct projections)
corticobulbar tract: motor cortex to brainstem (less direct pathway)

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20
Q

what 2 structures do motor fibers form after the internal capsule?

A

cerebral peduncles, then pyramids

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21
Q

pontine fibers

A

fibers between cerebral peduncles and pyramids

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22
Q

where do the motor fibers cross the midline?

A

at the pyramidal decussation (medulla)

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23
Q

what function do monkeys with lesions to the pyramids lose?

A

loose control of individual fingers

24
Q

what is the brainstem involved in?

A

stereotyped movements of the head (lateral pathway), posture and balance (medial pathway), vuluntary control of body and head

25
what are the 3 medial brainstem pathways for posture and balance?
tectospinal tract, vestibulospinal tract, reticulospinal tract
26
what is the main lateral brainstem pathway for voluntary limb movement? describe it's path
rubrospinal tract red nucleus -> contralateral dorsolateral column -> dorsolateral gray matter
27
where do descending motor projections terminate? what do the direct connections control?
direct: ventral horn motor neurons for control of fingers indirect: on premotor interneurons
28
where are central pattern generators located (for rhythmic motion)
spinal cord intrinsic circuitry
29
what is the basal ganglia involved in?
voluntary movement, cognition, emotion
30
what are the 4 interconnected subcortical nuclei of the basal ganglia? which one receives input? which one does output come from?
striatum (inputs; caudate and putamin), globus pallidus (output from internal segment), substantia nigra, subthalamic nucleus (look at pics in notes!!!)
31
what structures form the lateral and floor of the lateral ventricles?
lateral: caudate nucleus floor: thalamus
32
which thalamic nuclei connect the cerebellum and basal ganglia with the motor cortex?
ventral anterior, ventral lateral nuclei
33
what type of input from what structures does the putamin recieve?
excitatory from cortex excitatory and inhibitory from substantia nigra pars compacta
34
explain the direct vs indirect pathways from basal ganglia to cortex
dopaminergic input from substantia nigra excites direct pathway (putamin -> inhibits globus pallidus internal segment -> excites thalamus -> excites cortex and facilitates movement) and inhibits indirect pathway (putamin -> inhibits globus palllidus outer segment -> strops inhibiting subcortical nucleus -> excites globus pallidus internal segment -> inhibits thalamus -> inhibits cortex and inhibits movement)
35
what diseases can arise from abnormal function of basal ganglia? describe them a little
parkinson's disease (hypokinetic disorder: reduced direct pathway activity -> some spontaneous movements) and huntington's disease (hyperkinetic disorder: reduced indirect path activity -> excessive unwanted movements)
36
what does tonic output from basal ganglia do?
inhibits mesencephalic locomotion region neurons (inactivates locomotion central pattern generators)
37
the 4 functions of the loops we learned that basal ganglia is involved with?
motor control, eye movements, executive/associative(cognition), executive/motivation(Addiction)
38
what is the cerebellum main involved with?
planning, controlling, executing movements; most important for coordination
39
name and describethe 3 disorders we learned about that can be caused by cerebellar damage
ataxia: can't execute voluntary movements; no coordination intention tremors: tremor mostly at the end of a movement (more precisely from spinocerebellum feedforward projections damage) decomposition of movement: fragmentation of complex movements
40
what are the cerebellar folds called? and what do they do
folia: increase surface area
41
describe the regions of the cerebellum from medial to lateral
spinocerebellum for proprioception: vermis (projects to fastigial nucleus), intermediate hemisphere lateral hemispheres flocculonodular lobe (inferior in vestibulocerebellum; for reflex eye movements and balance)
42
name the 3 cerebellar peduncles and what passes through each
superior: outputs from deep nuclei to brainstem and thalamus (smaller most medial) middle: inputs from cerebral cortex through pontine nucleus (bigger most lateral) inferior: inputs from spinal cord (direct & indirect through brainstem) and vestibular nuclei
43
name the deep nuclei from most medial to lateral!
fastigial (in vermis), interposed (intermediate hemisphere), dentate (biggest in lateral hemisphere)
44
name the 3 layers of the cerebellar cortex from outer to inner, surrounding white matter
molecular layer (1/2 of neurons r there), Purkinje cell layer (monolayer), granule cell layer
45
what do mossy fibers do (explain path)
leave white matter, makes excitatory connection with granule cells & deep nuclei neurons, granule cells form densely packed parallel fibers that make excitatory connections with purkinje cells (causing simple spikes in purkinje regulated by stimuli and movement)
46
what are beams? (in cerebellum) what do basket cells do?
bundles of parallel fibers making functional rows that excite purkinje cells dendrites. basket cells inhibit purkinje cells (lateral inhibition)
47
what other cell type do purkinje cells recieve input from and what do those cells do?
climbing fibers: innervate 5-10 purkinje cells each providing powerful excitation input through complex spikes. originate from inferior olive and send collateral excitatory projection to deep nuclei
48
explain complex spikes
input from climbing fibers to purkinje cells. Has a long depolarization moment caused by voltage-gated calcium channels and smaller sodium spikes. Occur at a steady slow frequence. Detect specific events (timing is important).
49
describe deep nuclei's inputs and outputs
excitatory input from mossy fibers and climbing fibers. inhibitory input from purkinje cells. excitatory output to brainstem and thalamus. inhibitory output to inferior olive.
50
what input do the vermis and intermediate hemispheres (spinocerebellum) receive & through what structures?
somatic sensory input, efference copy of motor commands through mossy fibers from spinal cord of brainstem reticular formation
51
where does the vermis project to?
to the fastigial nucleus which then projects to the vestibular nuclei and reticular formation. involved in posture
52
where do the intermediate hemispheres project to? (1 nuclei -> 2 spots)
to interposed nuclei which project to primary motor cortex via ventral thalamic nucleus, and to magnocellular red nucleus for control of limb and movements
53
describe the cerebrocerebellum and its function
made of lateral hemisphere. Get input from cortex and sends it to frontal lobes and parvocellular red nucleus through dentate nucleus. it is involved in planning, programming, timing, complex movement sequences
54
what 3 things does the cerebellum compute to make a motor command
motor command efference copy, sensory input, internal model of motor effectors
55
what enables the cerebellum internal forward model to be updated (implicit motor learning)?
sensory feedback causing a sensory prediction error (maybe coming from internal olive)
56
explain long-term depression (jcomprend pas tbh)
form of synaptic plasticity involving synapses in which simple and complex spikes occur concurrently causing a reduced efficacity. complex spikes eliminate simple spikes causing movement errors. involved in motor learning
57
what do stellate and gogli cells do?
stellate inhibit synapses in adjacent rows of purkinje cells golgi inhibit granule cells when activated by their parallel fibers