10 - motor control 1

Question 1

how do we control our movements?

Answer 1

most actions require

• multiple muscles
• precise timing - between the two hands
• multiple components of movement

Question 2

what are the higher cognitive aspects of motor control

Answer 2

Include: 
• Planning and timing 
• Sequencing 
• Imagery (cf mirror neurones) 
• Expertise (e.g. sport, musical instrument)

Question 3

applications of understanding motor control

Answer 3

Include: 
• Planning and timing 
• Sequencing 
• Imagery (cf mirror neurones) 
• Expertise (e.g. sport, musical instrument)

Question 4

key cortical motor areas

Answer 4

prefrontal cortex
premotor cortex
supplementary motor cortex
primary motor cortex
central sulcus
primary somatosensory cortex
posterior parietal cortex

Question 5

what does the primary motor cortex control

Answer 5

execution

Question 6

what does the premotor cortex control

Answer 6

preperation of actions

Question 7

what does the prefrontal cortex control

Answer 7

higher level of planning

Question 8

what does the parietal cortex control

Answer 8

sensory-motor links

Question 9

primary motor cortex - organisation

Answer 9

• Pre-central gyrus
• Somatotopic organisation (from soma “body” and topos “place”)
• Activation in particular parts of M1 causes movement of particular body parts on opposite
side
tms - moving sccross motor cortex effects movement

Question 10

what happens in brain lesions

Answer 10

Stroke affecting one side of the brain can affect movement of the opposite side of the body

Question 11

what is Hemiplegia

Answer 11

paralysis of one side

Question 12

what is Hemiparesis

Answer 12

weakness of one side

Question 13

how does M1 code movements

Answer 13

• Cells in M1 have a preferred direction of movement

* Populations of cells code the direction of movement - vector coding

Question 14

what happens in M1

Answer 14

somatotopic activation

Question 15

how is the primary somatosensory cortex mapped

Answer 15

somatotopic mapping

Question 16

what is M1

Answer 16

primary motor cortex

Question 17

what are the connections in M1

Answer 17

input from supplementary motor area, premotor area and primary somatosensory area

output to spinal cord - control of muscles

Question 18

frontal eye fields

Answer 18

Eye movements are controlled by a different cortical area

Question 19

what do bodily movements rely more on

Answer 19

proprioreception - need to know where your body is in space

Question 20

what are the two main types of eye movement

Answer 20

1. Saccades

2. Smooth pursuit

Question 21

what are saccades

Answer 21

• Fastest movement we make, up to 1000 deg/sec Right
• Duration 20-200 ms
• Perception is suppressed during the movement - otherwise wed see a lot of blurring

very fast eye movements make all the time
degrees of visual angle
as explore visual scene drawn to different parts on the screen

Question 22

what is smooth pursuit

Answer 22

• Smooth tracking movement
• Up to approx 50 deg/sec
• Not usually observed in the absence of a stimulus
- cant move eyes smoothly unless theres something to follow
Slower than saccadic eye movements E.g. following a finger

Question 23

what happens in the lateral premotor cortex

Answer 23

• Lateral Premotor Cortex – externally generated actions
  E.g. metronome going - tap finger in time with it
  Something is telling you timing of what you ought to be doing

Question 24

what happens in the supplementary motor area

Answer 24

• Supplementary Motor Area – (medial PC) internally generated actions e.g. well learnt
sequences
Voluntary initiations - you decide when going to go - dont wait for green man just go when ready to go

Question 25

what is the premotor cortex important for

Answer 25

importan for coordinating actions between different limbs or muscles

Question 26

which are the areas more active in more difficult bimanual tasks

Answer 26

cerebellum - sub-cortical area SMA - supplemementary motor area pre-motor area good at cooridnating between the hands People who are drummers often learn to dissociate between the hands to do more complex rhythms

Question 27

what happens in sequence learning

Answer 27

``` faster and more accurate movements change from effortful to automatic practiced over and mover - less errors learned to produce sequence e.g. piano, touch type, driving ```

Question 28

what happens in sequence learning

Answer 28

changes over time

Question 29

what brain areas decrease activation with changes over time

Answer 29

dorsolateral prefrontal lateral premotor cortex primary motor

Question 30

what brain areas increase activation with changes over time

Answer 30

supplementary motor area

Question 31

TMS in SMA

Answer 31

Repetitive TMS to block activity | • SMA only interfered with performing the most complex sequence

Question 32

is prefrontal higher level

Answer 32

Choosing what action to perform (e.g. which finger, Frith et al. 1991) • Attention to action – when difficult or learning • Longer term goals and intentions - deciding what and what not to do • Not specific to action, e.g. generating random numbers

Question 33

what can prefrontal lesions produce

Answer 33

perseveration utilisation behaviour disinhibition frontal apraxia

Question 34

what is perseveration

Answer 34

Perseveration – repeat same action when no longer relevant

Question 35

utilisation behaviour

Answer 35

Utilisation behaviour – act on irrelevant (or inappropriate) object in environment Patient with prefrontal damage - picks up glasses and puts them on - neurologists glasses - glasses invite you to put them on E.g. take someone elses drink - socially unacceptable Doing actions when shouldn’t be done

Question 36

disinhibition

Answer 36

e.g. antisaccade task

Question 37

frontal apraxia

Answer 37

Frontal apraxia – not able to follow steps in routine tasks (e.g. making tea)

Question 38

what is antisaccades

Answer 38

Required to look in opposite direction to the target • Must inhibit (pre-potent) tendency to look at target Look in opposite direction - dont look at target - move in opposite direction In patient with prefrontal lesions - more errors - look in direction of target when should be looking in other direction

Question 39

normal and shallice model - what is contention schedulling

Answer 39

selects appropriate schema automatic dont pay any attention

Question 40

what is supervisory attentional system | normal and shallice model

Answer 40

required for novel/less automatic decisions need when learning a new system tired- more likely to make errors when SAS doesnt kick in

Question 41

what is perseveration as an action error

Answer 41

unable to change schemas when no longer appropriate

Question 42

what is utilisation behaviour as an action error

Answer 42

schemas activated by environment without SAS suppressing them

Question 43

what can damage to the parietal cortex lead to

Answer 43

apraxia | inability to perform skilled purposeful movement

Question 44

posterior parietal cortex

Answer 44

Representing where things are mapped out in world - important Performing and understanding movements

Question 45

ideomotor apraxia

Answer 45

Idea and execution disconnected – retain knowledge of action • Can recognise action performed by another • Fail in pantomiming action (e.g. body part as tool) - e.g. hand as toothbrush rather than person doing brushing • Can perform sequence but not components

Question 46

what are the subcortical motor areas

Answer 46

basal ganglia | cerebellum

Question 47

cerebellar patients can lead to

Answer 47

• Action tremor - tremor of body during action - contrasts with parkinsons disease • Dysmetria – over and undershooting of movements - movements are too big or small for whats needed • Deficits in: – coordinating across joints – Motor learning – Timing overshoort in random saccade task finger to nose test

Question 48

how many people have parkinsons disease

Answer 48

1 in 1000, 1 in 100 over 65 | issues in the basal ganglia

Question 49

what are the 3 cardinal motor systems

Answer 49

bradykinesia - slow movement tremour - resting rigidity - stiffness when moving joint shuffling

Question 50

what causes parkinsons

Answer 50

death of dopaminergic cells in the substantia nigra pars compactica

Question 51

writing in parkinsons

Answer 51

Small in size • May reduce while writing - fatigue micrographia - smaller in size