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KNES 451 > control of somatosensory feedback (goal directed actions) > Flashcards

control of somatosensory feedback (goal directed actions) Flashcards

1
Q

what is the cuneate fascicle

A

carries sensory info from the upper body and trunk
- at or above T6
- more white matter - more info being routed to the brain with less spinal processing

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2
Q

what is the gracile fascicle

A

carries sensory info from the lower limbs and trunk
- only gracile present below T6
- more grey matter and less white matter (more spinal processing)

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3
Q

what is the organisation of the fascicles in the spinal cord

A

medial to lateral = gracile to cuneate
feet = medial
hands = lateral
(think person standing in a T - move up from feet and out to hands as medial to lateral)

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4
Q

where are sensory and motor neurons in the spinal cord

A

sensory neurons = dorsal horn
motor neruons = ventral horn

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5
Q

what is the internal capsule

A

white matter tract that carries info from the thalamus to S1

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6
Q

what is the purpose of the thalamus in this context

A

relay centre fro somatosensory info form the periphery to S1

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7
Q

what is the VPMn

A

ventral posterior medial nucleus
- somatosensory info from the head, face, and neck

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8
Q

what is the VPLn

A

ventral posterior lateral nucleus
- somatosensory info from the rest of the body

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9
Q

what are the properties of long latency reflexes (50-105 ms post perturbation)

A
  • recruit sensory and motor circuits in the brain
  • show flexible goal directed processing
  • slower but more functional than SLRs
  • processing capabilities of LLRs depend on the task
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10
Q

when do LLRs increase

A

when the goal of the task is to resist a mechanical perturbation

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11
Q

where are CM cells concentrated

A

anterior (rostral) bank of the central sulcusw

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12
Q

why is it useful to target CM cells to study activity in M1

A

neurons connect directly onto aMNs
- don’t have to worry about interneurons

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13
Q

what is the initial response when asked to push or pull the handle, regardless of anything else

A

initial excitatory response regardless of perturbation and then M1 neurons show rapid, goal directed responses

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14
Q

what is the response when the perturbation is opposite to the goal

A

clear sustained activity until the hand enters the target
fires until the goal is obtained and then stops firing

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15
Q

what is the response when the perturbation is in the same direction as the goal

A

neuron shuts off until the hand enters the target
resumes low level background activity

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16
Q

what does the posture control vs movie task examine

A

how the task goal influences the time course of somatosensory processing and resulting perturbation responses

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17
Q

what is the order in which areas respond to somatosensory feedback

A
  1. S1
  2. area 2
  3. area 5 (parietal)
  4. M1
  5. PMd (dorsal premotor)
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18
Q

what does the order in which brain areas are activated correspond to

A

the order the brain areas receive somatosensory feedback from the periphery

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19
Q

what is the order in which areas respond to somatosensory feedback in a task dependent way (show goal directed response)

A
  1. area 5
  2. M1
  3. S1 (area 3a)
  4. PMd
  5. area 2
20
Q

why is area 5 the first area to respond in a task dependent way

A

responds quickly because it’s activity often depends on the goal
- important in attention

21
Q

why is M1 faster at responding in a task dependent way than S1

A

info travels from area 5 to M1 directly
- generates a motor command that is different for different goals

22
Q

what is the role of S1 in task dependent responses

A

responds to feedback and the feedback differs depending on the mvmt

23
Q

how can the onset of task directed processing be revealed

A

subtract the default perturbation response in posture task from the goal directed response

24
Q

what is the differences between the posture control task and movie task

A

posture control
- hand perturbed from green target and need to get back within a certain amount of time
- need to respond quick for reward

movie task
- reward regardless of response to perturbation
- elicits no response (or very little)

25
Q

what is the functional anatomy of the cerebellum

A

symmetrical - 2 hemispheres
3 sets of deep cerebellar nuclei
fractured somatotopy (all areas are recognised but not organised)

26
Q

what does the spinocerebellum contain

A

vermis and intermediate hemispheres

27
Q

which deep cerebellar nuclei are in the spinocerebellum

A

fastigial nucleus (vermis)
interposed nuclei (intermediate hemispheres)

28
Q

what does the cerebrocerebellum contain and what is its function

A

lateral hemispheres
higher level, goal directed processing

29
Q

which deep cerebellar nuclei are in the cerebrocerebellum

A

dentate nuclei

30
Q

what is the effect of a cryoloop

A

causes reversible focal inactivation by lowering tissue temp until neurons stop firing (~21 C)
- changes the neurons excitability by changing the ion concen
- used to assess how the brain areas contribute to behaviour

31
Q

what was the purpose of cryoprobes in the cooling experiment with monkeys

A

enable direct control of the function of the interposed and dentate nuclei to quantify impact on behaviour

32
Q

what was the impact of cerebellar cooling on perturbation responses

A

interferes with sensory processing and begins to cause oscillatory corrective responses disrupting task behaviour

(smooth correction back to postural target in absence of cooling)

33
Q

what was the impact of cooling on cortical recordings in M1 and EMG

A
  • increased amplitude and improperly timed triceps (antagonist) EMG
  • increased oscillations
  • increased amplitude and phasic bursts of biceps EMG
  • increased amplitude and phasic bursts of M1 neuron
34
Q

are the behaviour impairments caused by proprioception or vision deficits

A

proprioception
- oscillations, and improperly timed and scaled responses are seen in vision and no vision conditions
(doesn’t matter if vision is present or not because it’s so slow to process feedback)

35
Q

where are electrodes placed for stimulas and instruction dependent activity in the cerebellum

A

interposed and dentate nuclei

36
Q

what do interposed nuclei process

A

process sensory feedback
(don’t reflect the goal)

37
Q

what do interposed nuclei respond to

A

direction of motion (inhibited during opposite direction) - have a preferred direction
- sensitive to motion but not the goal

38
Q

what do dentate nuclei process

A

higher level processing
process feedback in a goal directed way
- sensitive to task instruction

39
Q

what do dentate nuclei respond to

A

goal of the task
- responds or inhibited based on the goal regardless of the direction / perturbation
doesn’t respond to direction of motion

40
Q

what is the effect of cooling PMd on task performance

A
  • hand displaced further
  • hand returns slower
  • larger endpoint errors
    (deviations increase as cooling continues)
41
Q

what is the effect of cooling area 5 on task performance

A
  • respond more vigoursly
  • hand displaced less than baseline
  • hand returns faster
  • displays larger endpoint errors
42
Q

are neural responses in M1 larger when the hand is bumped towards or away from the target

A

larger when bumped away

43
Q

when do goal related difference in M1 processing emerge

A

50-60ms after perturbation

44
Q

why are there different responses before the perturbation is turned on

A

differences in set up allow for pre planning
- neurons that are sensitive in that direction can fire more APs

45
Q

why does it show potential that goal directed processing can happen outside M1

A

if everything happened in M1, the neural response lines shoudl be separate the whole way

46
Q

are EMG responses larger when the hand is pumped away or towards the target

A

larger when bumped away

47
Q

when do goal related differences in EMG emerge

A

60-70ms after perturbation
- after M1 burst of activity

KNES 451 (11 decks)

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