L7

Question 1

feedback control

Answer 1

task of loop is to minimize difference between desired input and actual output.

Question 2

feedforward control

Answer 2

visual info (and memory) used to generate anticipatory  command using internal model "memory" of the responses of muscles to neural commands
- feedback control corrects for residual errors

Question 3

does motor cortex control individual muscles or overall movement?
- evidence for control of single muscles

Answer 3

• firing of some motor cortex cells is well correlated with single muscle force
• focal stimulation via microelectrodes can activate muscles
• even TMS can activate single muscles if these are voluntarily pre-activated

Question 4

motor cortex control for individual or overall movement?

-evidence for multiple muscles (synergies) and types of movement

Answer 4

• histology shows corticospinal tract axons nearly always innervate the motoneuronal pools of several muscles
• TMS ONLY actiavtes single muscle that are voluntarily pre-activated. increase TMS strength recurits lless pre-activated muscles
• spike -triggered averaging of EMG: response in more than one muscle.
  4 muscles dhowed EMG response following spikes in single motor cortex neuron.

Question 5

motor cortex neurons organized?

output neurons cause ? and respond to

deeper into cortex = more or less firing?

Answer 5

in columns of input/output modules
cause movement & respond to movement-related sensory feedback .

less firing as it goes deeper in ocrtex.

Question 6

cortical popln vectors

• preferred ??
• what is population vector?
• centre-out movement indicates?

Answer 6

direction
vectorial sum of all individual neurons’ preferred direction vvectors.
indicates group activity of cortical neurons is well correlated w movement direction.

Question 7

effect of loading arm on cortical neuron’s firing rate as monkey performs movements in different directions.

Answer 7

polygon arouns area showing firing rates increases in sie the more the load direction opposes the preferred direction.

Question 8

conclusions

Answer 8

voluntary movement direction predictable from poln vector

• firing rates of MC neuron depend on external load
• firing rate depend on precision, speed, relevance and importance of movement, not just direction and force
• some MC neurons only fire if individual joint involved
• MC nuerons sometimes not directly connected to spinal MNS

Question 9

few functions of supplementary and premotor areas

Answer 9

• upstream from MC
• inputs from motivational aras.
• generate commands for movement
  match posture to voluntary
  coordinate L&R hands.

Question 10

visuomotor coordination
- visual perception different than visual-guided acts.
ventral stream mediates?
dorsal stream mediates?

Answer 10

V - what = shape recognition and discrimination

D - where/how = motor responses

Question 11

MC lesions

Answer 11

hemiplegia
loss of fine finger and hand movement
spasticity
babinski response (normally curl toe, babinski = fan toe
dysarthria

Question 12

SMA, premotor lesions

Answer 12

apraxia

poor bilateral coordination