lecture 8 - motor system

Question 1

functions of motor system during hand movement (8)

Answer 1

1. visual info - locate target
2. frontal-lobe motor area - plan
3. spinal cord carries info
4. MN to muscles
5. sensory
6. sensory cortex receives message
7. BG judges, cerebellum corrects
8. spinal carries sensory to brain

Question 2

roles of brain areas in motor control
posterior cortex
prefrontal cortex
premotor cortex
motor cortex

Answer 2

PC - sensory info to frontal cortex
PFC - plan movement
PMC- organizes movement
MC - produces specific movement

Question 3

lateral brain araes

Answer 3

frontal eye field
premotor cortex
primary motor cortex
broca's area
parietal cortex

Question 4

medial brain areas

Answer 4

supplementary motor area
primary motor cortex
anterior cingulate

Question 5

Macaque single cell recording  - flex & extend
-- findings
firing
weight
direction

Answer 5

hold bar, when cued - flex or extend. increased resistence with pulley.
- frequency of firing increases before movement = planning.
no resistance: MN active before and through action
with resistance: more activity in planning, more activity in action. - neurons code for direction

Question 6

movement coding by neurons in the neocortex
monkey cortex, different directions

• maximal firing? further from?

Answer 6

findings: each M1 neuron is maximally activate to a particular direction.
- activity decreased in proportionn to displacement form preferred direction
conclusion: MN calculate distance and direction of movement
- move lever in different directions with electrode motor-cortex neuron. fire maximally at 180 degree in front of body. further from that = less firing = spatial gradient

Question 7

naming tools & brain

Answer 7

increase blood flow to hand region of motor cortex = relationship btw tool and idea of action

Question 8

listening to music & motor cortex

Answer 8

pianist = activation in motor cortex, specifically hand area. “thumb” portion may be added for certain songs.
audition related to manual training

Question 9

rolling ball on table

- overt vs imagery

Answer 9

overt - evoke activity in cerebellum, sensory and motor areas.
imagery - no cerebellum activity, more activity in prefrontal cortex

Question 10

Primary motor cortex - M1

neuronal population vector model

Answer 10

neurons are limited - need to work together to add/subtract to get desired “direction” that’ll lead to correct motor movement

Question 11

motor plan

- 5 elements.

Answer 11

plan
goal info
neuromuscular control info
sensory?
coarticulation? - vocal and face muscles, prepare for word before you speak.

Question 12

how far in advance in motor plan mad?

Answer 12

few steps ahead - plans phrase before speaking
on the fly? no..
entirely planned before action = whole two line phrase probably not planned, one line at a time.
longer phrase = slower to start.

Question 13

cerebellum
- organized?
- most medial part? what happens when lesioned?
intermediate zone - lesion?
lateral zone - fxn? 
floccular lobe

Answer 13

organized ipsilaterally
medial = vermis. lesion = fall ipsilaterally to lesion.
inter = for smooth movements. tremors if lesion
lateral - motor planning; multi-joing movement
flocc - needed for eye movements and balance.

Question 14

2 types of tremors

Answer 14

intentional tremor = at start and end of movement

action tremor = on the way to target

Question 15

ballistic movement vs multi-joint

Answer 15

ballistic = one quick movement - overshoot? = hypermetria. issue w motor planning.

Question 16

cerebellar damage and hypermetria

2 key differences

Answer 16

overshoot

1. agonist and antagonist have multiple firing peaks
2. peak between agonist and antagonist is 2x as long as normal.

Question 17

cerebellar damage & prism goggles

Answer 17

trying to see if cerebellar damage patients can learn do motor learning.
goggle shift foveal representation.
neuro intact = prism goggles = poor accuracy, but readjust motor so it hits. after prism - take time to get back to normal
cerebellar damage - high variance in initial throws pre-goggle. with goggle, no adaptation of motor = consistently poor. remove goggles - immediately same as pre-goggle. no mtoro learning

Question 18

what is motor learning

Answer 18

motor system learns new skills.

Question 19

supplementary motor area
- motor planning?
what else is it involved with?

Answer 19

like in M1, SMA active before start of action.

- state of readiness for action, action initiation, complex movements, motor imagery

Question 20

SMA proper vs pre- SMA

Answer 20

proper - main, more posterior

pre- more anterior.

Question 21

what splits brain into front & back

Answer 21

anterior commisure

- splits SMA

Question 22

when does pre-SMA peak?

when does proper SMA peak

Answer 22

pre - visual peak is large and motor response is weak
proper - dampened visual peak, greater motor peak
- nc visual is smaller peak , probs dampened bc going through hippocampus.

Question 23

mirror neurons

• fire when?
• encode what?
• used for ?
• part of movement is absent =

Answer 23

• fire when we see others make a movement.
• encode complete action. -used for imitating, understanding others.
• fill in the blanks. PMC holds mirror cells. MN in premotor doesnt respond when absent, but responseds when it’s absent or hidden. neuron fires with understanding of action

Question 24

where are human mirror neurons?

-role? importance for?

Answer 24

left hemisphere - maybe overlap w broca’s.

• self action, perception of self-awareness, awareness of actions of others.
• important for gestures & verbal language

Question 25

BG - 3 important areas.

pathway?

Answer 25

caudate putamen, amygdala, subs nigra.

non linear, cooperation and reciprocity.

Question 26

disorders of BG

Answer 26

huntingtons chorea - destroy caudate putamen.
involuntary exaggerated movement
-chorea: twitching, related to action, initiation, extremity problem
-athetosis (writhing) - midline problem

PD - loss of DA in subs nigra
- muscular rigidity and difficulty initiating and performing movement. 
akinesia - no spontaneous movement
bradykinesia - slow
tremors

Question 27

PD handwriting profile

Answer 27

normal patient: even sequence btw acceleration/deceleration

PD: components dissimilar - interrupted, longer to complete.

Question 28

Anterior cingulate cortex ACC
-function in?
motor modulation
topographic organization with different effectors

Answer 28

attention, emotion, vigilance, novel/cognitive actions
- A->B; M->L. then switch A->L, M->B. saw ACC activate upon new task
- eye = anterior (frontal eye field); speech = medial ACC (brocas); actions = posterior (PC)
stroop task - incogruent, harde to say words, evoke activtiy in ACC

Question 29

parietal lobe & motor control

- AIP

Answer 29

anterior intraparietal culcue - gauge grip, automatic. mouth gauge too.

Question 30

cortical motor disorders

Answer 30

apraxia

callosal apraxia

Question 31

apraxia =
lesions in
- oral
- limb

Answer 31

problem w actions that are skilled, sequential, purposeful.

• oral = frontal- temporal lesion. rarely presents w broca’s aphasia
• limb = left parietal- temporal lesions

Question 32

limb apraxia

• lesions
• presentation

Answer 32

lesion in parietal-temporal areas.
- pantomme difficulty - cant mime with object.
imitation
symbolic action - trouble understanding
effector selection - choosing hand when asked is hard

Question 33

callosal apraxia

Answer 33

problem performing action w left hand in response to verbal command.
- assoc with damage to crossover. info to use left hand needs to cross to right hemisphere - unable or incorrect crossing due to lesion or tumor.
degradation of info - action not the same