Motor Control I

Question 1

what are the 3 different levels of motor control functional hierarchy?

Answer 1

Strategy – the goal and the movement strategy to best achieve this goal

Tactics – the sequence of spatiotemporal muscle contractions to achieve a goal smoothly and accurately

Execution – activation of motor neuron and interneuron pools to generate goal-directed movement

Question 2

what structures are part of the function strategy?

Answer 2

Association neocortex, basal ganglion

Question 3

what structures are part of the function tactics?

Answer 3

Motor cortex, cerebellum

Question 4

what structures are part of the function execution?

Answer 4

Brain stem, spinal cord

Question 5

what do the lateral pathways of the spinal cord control?

Answer 5

voluntary movements of distal muscles – under direct cortical control

Question 6

what do ventromedial pathways of the spinal cord control?

Answer 6

posture and locomotion – under brain stem control

Question 7

what is the important/longest lateral pathway?

Answer 7

Cortocospinal tract (CST)

Question 8

where does the CST originate from?

Answer 8

areas 4 and 6 of frontal motor cortex – rest is somatosensory

Question 9

where does the CST decussate(cross over)?

Answer 9

at medulla/spinal cord junction

Question 10

what is the smaller lateral pathway?

Answer 10

rubrospinal tract (RST)

Question 11

where does the RST start in?

Answer 11

red nucleus of midbrain – inputs from same cortical areas as CST

Question 12

what occurs if there is a lesion of CST and RST?

Answer 12

fine movements of arms and hands lost. Can’t move shoulders, elbows, wrist and fingers independently.

Question 13

what occurs if there is a lesion of CST alone?

Answer 13

same deficits, but after few months functions reappear. Been taken over by RST

Question 14

what two ventromedial pathways control posture and locomotion?

Answer 14

Vestibulospinal(VST) and Tectospinal(TST) tracts

Question 15

what is the role of VST & TST?

Answer 15

VST stabilizes head and neck

TST ensures eyes remain stable as body moves

Question 16

what two ventromedial pathways control trunk and antigravity muscles?

Answer 16

Pontine and medullary reticulospinal tracts

Question 17

where does the VST & TST originate?

Answer 17

VST-vestibular nucleus

TST-superior colliculus

Question 18

where does the Pontine and medullary reticulospinal tracts originate?

Answer 18

pons + medulla

brainstem

Question 19

describe the role of the Pontine and medullary reticulospinal tracts?

Answer 19

Use sensory information about balance, body position and vision

Reflexly maintain balance and body position

Question 20

what occurs when the motor cortex directly activates spinal motoneurons?

Answer 20

frees them from reflex control by communicating via nuclei of ventromedial pathways

Question 21

describe the Lower motor neurone distribution

Answer 21

somatotopic-

Medial ones control axial and proximal limb muscles, lateral ones innervate distal limb muscles

Question 22

where does the mosaic of premotor areas lie?

Answer 22

anterior to primary motor cortex

Question 23

what does the Somatotopic organisation of primary motor cortex mean?

Answer 23

point-for-point correspondence of an area of the body to a specific point on the primary motor cortex

Question 24

what are the two somatotopically organised motor maps in area 6?

Answer 24

premotor area - PMA and supplementary motor area - SMA

Question 25

what do the SMA & PMA innervate?

Answer 25

SMA innervates distal motor units directly | PMA connects reticulospinal neurones innervating proximal motor units

Question 26

what can microstimulation in a specific area of the primary motor cortex elicit?

Answer 26

see movements that bring hands to mouth, or into central space, to inspect, or to manipulate, or to defend.

Question 27

where in the brain are decisions taken about what actions/movements to take and their likely outcome?

Answer 27

prefrontal and parietal cortex

Question 28

what parts of the brain generate the mental image of body in space?

Answer 28

somatosensory, proprioceptive and visual inputs to posterior parietal cortex (areas 5 and 7)

Question 29

where is the junction where signals encoding what actions are desired are converted into how the actions will be carried out?

Answer 29

area 6

Question 30

what is area 4 for?

Answer 30

“doing the desired movement” by activating the neurones of the CST and RST

Question 31

decision making neurones in cortical PMA fire when?

Answer 31

when movement is made and when movement is imagined ie before it occurs they also fire when others make the same specific movement