w3+w4 Motor systems

Question 1

motor plan

Answer 1

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)

Question 2

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

Answer 2

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

Question 3

part of the CNS responsible for reflexes

Answer 3

spinal cord

Question 4

executing motor programs

Answer 4

motor cortex

Question 5

gating and control over action based on motivation, affective state

Answer 5

basal ganglia

Question 6

adjusting ongoing behavior, timing

Answer 6

cerebellum

Question 7

Sylvian fissure

Answer 7

the same as the lateral fissure

Question 8

transverse fissure

Answer 8

Question 9

hierarchies in the motor system

Answer 9

Question 10

lateral cortical spinal tract

Answer 10

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

Question 11

primary motor neurons

Answer 11

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

Question 12

lower motor neurons

Answer 12

directly control muscles

Question 13

local circuits

Answer 13

after/down the spinal cord

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

Question 14

central pattern generators

Answer 14

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

Question 15

topology of the motor system in the spinal cord

Answer 15

medial to lateral

Question 16

we can electrically stimulate a complex movement - so what?

Answer 16

“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

Question 17

planning sequences of action: SMA

Answer 17

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

Question 18

planning sequences of action: PMC

Answer 18

PMC involved in the initiation and termination of cued sequences

Action / motor unit linked representations

“Working memory for action”

Question 19

function of the basal ganglia

Answer 19

exert control over action selection

Question 20

cortico-striato-thalamic loop

Answer 20

Question 21

basal ganglia: direct vs indirect pathways

Answer 21

Question 22

when are the basal ganglia the most active?

Answer 22

when learning new motor skills

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

Question 23

anatomy of the cerebellum

Answer 23

Question 24

functions of the cerebellum

Answer 24

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

Question 25

damage to the cerebellum

Answer 25

Midline: truncal ataxia

• Unsteady gait
• Seems drunk

Lateral cerebellar cortex: appendicular ataxis

• Non-smooth movement
• Intention Tremor during voluntary movement

Question 26

motor system vs motivation

Answer 26

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

Question 27

damage to cortical motor areas

Answer 27

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

Question 28

Subcortical motor disease leads to

Answer 28

changes in the goal-directedness or smoothness of motor behavior

Question 29

Parkinson’s disease

Answer 29

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

Question 30

the anatomy behind Parkinson’s disease

Answer 30

Question 31

DA in the brain

Answer 31

so dopamine

Question 32

DA: role in learning

Answer 32

Question 33

Parkinson’s: treatment

Answer 33

Question 34

Huntington’s disease

Answer 34

Question 35

anatomy behind Huntington’s disease

Answer 35

Question 36

Tourette’s syndrome

Answer 36

Heritable disease, sex-chromosome linked, expressed mostly in males

Link with OCD

Treatment:

DA-receptor antagonists

Haloperidol and others (Antipsychotic medication)

Strong side effects

Question 37

Tardive dyskinesia

Answer 37