w3+w4 Motor systems Flashcards

1
Q

motor plan

A

we don’t think about individual muscle contractions, we think about motor plans: I want to move my finger, not every muscle in it in a particular way

can be stimulated electrically (done on monkeys) in the primary motor cortex (so not a single muscle stimulated, but a complex movement)

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2
Q

areas in the brain that do initiation, stopping and planning of motor actions/sequences

A

pre-motor cortex (PMC) and supplementary motor area (SMA)

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3
Q

part of the CNS responsible for reflexes

A

spinal cord

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4
Q

executing motor programs

A

motor cortex

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5
Q

gating and control over action based on motivation, affective state

A

basal ganglia

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6
Q

adjusting ongoing behavior, timing

A

cerebellum

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7
Q

Sylvian fissure

A

the same as the lateral fissure

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8
Q

transverse fissure

A
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9
Q

hierarchies in the motor system

A
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10
Q

lateral cortical spinal tract

A

it’s the hierarchy of the motor system, but represented as anatomy

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11
Q

primary motor neurons

A

more common: upper motor neurons

travel from motor cortex or brain stem down the spinal cord to synapse onto local circuits

Lateral cortico-spinal tract

Cross over to contralateral side

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12
Q

lower motor neurons

A

directly control muscles

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13
Q

local circuits

A

after/down the spinal cord

can operate with a level of (reflex) autonomy. e. g. Pain reflexes

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14
Q

central pattern generators

A

neuronal circuits that can produce rhythmic motor patterns in the absence of sensory inputs: walking, breathing, flying, and swimming

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15
Q

topology of the motor system in the spinal cord

A

medial to lateral

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16
Q

we can electrically stimulate a complex movement - so what?

A

“course/broad tuning”

problem: we cannot predict direction/intensity from a single M1 neuron

means that movements are specified by populations of neurons. Combined output determines actual movement

17
Q

planning sequences of action: SMA

A

Sequences, more than repeated movements (Example: only active for “Pull, Push, Turn”, Activity aligned to “Push”, Not “Pull, Turn, Push”, Some neurons active for given position in sequence, irrespective of particular action required)

Self-generated more than cued motor sequences or action plans

Relatively abstract representations

18
Q

planning sequences of action: PMC

A

PMC involved in the initiation and termination of cued sequences

Action / motor unit linked representations

“Working memory for action”

19
Q

function of the basal ganglia

A

exert control over action selection

20
Q

cortico-striato-thalamic loop

21
Q

basal ganglia: direct vs indirect pathways

22
Q

when are the basal ganglia the most active?

A

when learning new motor skills

: blocks of new learning vs. normal execution: joystick mapping rotated 90 degrees

23
Q

anatomy of the cerebellum

24
Q

functions of the cerebellum

A

Error correction: To produce smooth movement, Compare motor output to actual produced movement, Dentate Nucleus (deep structure) outputs back to motor cortex

Motor learning: When acquiring new motor skills, large activations of cerebellum ▪ Like Basal Ganglia ▪ Could be related to large “errors” to be processed

Non-motor learning: Also involved in cognitive tasks. Huge input from prefrontal regions. Hypothesis: efficient circuit for error correction

25
damage to the cerebellum
Midline: truncal ataxia - Unsteady gait - Seems drunk Lateral cerebellar cortex: appendicular ataxis - Non-smooth movement - Intention Tremor during voluntary movement
26
motor system vs motivation
Value information or cueing from perception can bias motor preparation PPC: spatial goals with higher value more active SC: population action vectors can be manipulated
27
damage to cortical motor areas
M1: paralysis (often due to stroke) PMC: deficiency in cue-based sequencing behavior ▪ Need to maintain e.g. visual cues to keep plan active SMA: deficiency in self-generated sequences
28
Subcortical motor disease leads to
changes in the goal-directedness or smoothness of motor behavior
29
Parkinson's disease
Up to 60% of substancia nigra is destroyed: Trauma, tumors, Encephalitis Lethargica, MPTP, Frozen addicts Up to 80% of DA is lost: Brain tries desperately to compensate, Reducing degradation, Increasing receptors
30
the anatomy behind Parkinson's disease
31
DA in the brain
so dopamine
32
DA: role in learning
33
Parkinson's: treatment
34
Huntington’s disease
35
anatomy behind Huntington's disease
36
Tourette's syndrome
Heritable disease, sex-chromosome linked, expressed mostly in males Link with OCD Treatment: DA-receptor antagonists Haloperidol and others (Antipsychotic medication) Strong side effects
37
Tardive dyskinesia