10. Motor Control 1

Question 1

What do the ‘higher’ cognitive aspects of motor control include?

Answer 1

• Planning and timing
• Sequencing
• Imagery (cf mirror neurones) - can imagine movement without moving.
• Expertise (e.g. sport, musical instrument)

Question 2

What do actions require?

Answer 2

• Multiple muscles
• Precise timing (e.g. between the 2 hands)
• Multiple components of movement

Question 3

What is the motor function that the Primary Motor Cortex is key for?

Answer 3

Execution

Question 4

What is the motor function that the Premotor Cortex is key for?

Answer 4

Preparation of actions

Question 5

What is the motor function that the Prefrontal Cortex is key for?

Answer 5

Higher level of planning

Question 6

What is the motor function that the Parietal Cortex is key for?

Answer 6

Sensory-motor links

Question 7

Describe the Primary Motor Cortex (M1).

Answer 7

• In the Pre-central gyrus

- Somatotopic organisation (from soma “body” and topos “place”)

Question 8

What did Penfield’s study and TMS show?

Answer 8

Activation in particular parts of M1 causes movement of particular body parts on opposite side

Question 9

What is Hemiplegia?

Answer 9

Paralysis of one side

due to stroke

Question 10

What is Hemiparesis?

Answer 10

Weakness of one side due to stroke.

Question 11

Describe the Cells in M1 that code for movements.

Answer 11

• Cells in M1 have a preferred direction of movement

- Populations of cells code the direction of movement – VECTOR CODING

Question 12

What are the M1 inputs?

Answer 12

Supplementary motor area.
Premotor area
Primary somatosensory area

Question 13

What are the M1 outputs?

Answer 13

Output to spinal cord – control of muscles

Question 14

Describe how the brain is organised to improve signal transmission?

Answer 14

Info coming in about body parts is next to the part of the brain that send info out to those body parts

Question 15

What are eye and body movements controlled by?

Answer 15

• Eye movements are controlled by a different cortical area (cerebellum)
• Bodily movements rely more on proprioception

Question 16

What are the 2 main types of eye movement?

Answer 16

1. Saccades

2. Smooth pursuit

Question 17

Describe Saccadic Eye movements

Answer 17

• Fastest movement we make, up to 1000 deg/sec
  ○ Degrees of visual angle
• Duration 20-200 ms - short
  Perception is suppressed during the movement

Question 18

Describe Smooth Pursuit Eye Movements.

Answer 18

• Smooth tracking movement
• Up to approx 50 deg/sec
• Much slower movement that saccades.
• Not usually observed in the absence of a stimulus

Question 19

What role does the lateral premotor cortex play in motor movements?

Answer 19

• Externally generated actions
  ○ Located further out
  ○ Timing of movements is determines by an external stimulus (i.e. metronome)

Question 20

What role does the supplementary motor area (SMA) play in motor movements?

Answer 20

• (medial PC) internally generated actions e.g. well learnt sequences
  ○ Located more medially

Question 21

How does task difficulty affect activation of motor areas?

Answer 21

• Areas more active in more difficult bimanual tasks (Swinnen & Wenderoth, 2004)
• We are good at coordinating with our hands

Question 22

What are the brain areas important in bimanual coordination?

Answer 22

• Pre-Motor Area
• SMA
• Cerebellum

Question 23

What did Toni et al (1998) study investigate?

Answer 23

• Investigated Sequence learning.

- looked at the brain areas involved at different points through the process of seqence learning

Question 24

What is sequence learning?

Answer 24

• Faster and more accurate movements

- Change from effortful to automatic

Question 25

What did Toni et al (1998) study find?

Answer 25

- Changes over time of sequence learning: ○ Dorsolateral prefrontal ↓ ○ SMA ↑ ○ Lateral premotor cortex ↓ ○ Primary motor ↓ - Also subcortical - cerebellum and basal ganglia

Question 26

Why does the Motor Cortex activity decrease in sequence learning?

Answer 26

- you become more efficient at the movement so you are actually moving less. = less activation

Question 27

What effect of doing TMS over SMA did Gerloff et al., (1997) find?

Answer 27

- Repetitive TMS to block activity - SMA only interfered with performing the most complex sequence - Need SMA to do the particular task

Question 28

What is the evidence that the prefrontal cortex is involved in higher level motor movements.

Answer 28

Frith et al. 1991 - Ps choose which finger to move - Involved when paying attention to action – when difficult or learning - Longer term goals and intentions - Not specific to action, e.g. generating random numbers

Question 29

What can prefrontal cortex lesions produce?

Answer 29

- Perseveration – repeat same action when no longer relevant - Utilisation behaviour – act on irrelevant (or inappropriate) object in environment - Disinhibition e.g. antisaccade task - Frontal apraxia – not able to follow steps in routine tasks (e.g. making tea)

Question 30

What are the deficits associated with Parkinson's disease?

Answer 30

- Internal/external – more problems with internally generated movements - Complex movements – bimanual, sequences - Cognitive effects – attention shifting, everyday cognitive failures

Question 31

What causes shuffling in Parkinson's disease?

Answer 31

- Death of dopaminergic cells in substantia nigra pars compacta - 80% of dopaminergic cells have died in the substantia nigra before symptoms appear.

Question 32

What are the main 3 symptoms of Parkinson's Disease?

Answer 32

1. Bradykinesia – slow movement 2. Tremor (resting) - can often improve during a more precise movement 3. Rigidity

Question 33

What is Micrographia?

Answer 33

- Writing is small in size. | - May reduce while writing - fatigue

Question 34

What is apraxia, and what causes it?

Answer 34

- Inability to perform skilled purposeful movement | - Damage to the parietal cortex

Question 35

Describe the Anti-Saccade task.

Answer 35

- Required to look in opposite direction to the target | - Must inhibit (prepotent) tendency to look at target

Question 36

Describe the Norman & Shallice Model.

Answer 36

- a framework of attentional control of executive functioning. - sensory info & supervisory attentional system inputs into contention scheduling. - this outputs to the effector systems.

Question 37

Describe Contention scheduling in the Norman & Shallice Model.

Answer 37

- selects appropriate schema | - Occurs relatively automatically

Question 38

Describe the Supervisory attentional System (SAS) in the Norman & Shallice Model.

Answer 38

- Required for novel/less automatic actions | - When you are tired you are more likely to make these errors.

Question 39

Describe Ideomotor Apraxia

Answer 39

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

Question 40

What are the subcortical motor areas?

Answer 40

Basal Ganglia | Cerebellum

Question 41

What can Cerebellar damage cause?

Answer 41

- Action tremor - tremor of the body during action | - Dysmetria – over and undershooting of movements (movement are either too big or too small)

Question 42

What are the deficits seen in Cerebellar patients?

Answer 42

- Deficits in: ○ coordinating across joints ○ Motor learning ○ Timing - Predicting timing of movements

Question 43

How do Cerebellar patients perform in the Finger-to-Nose Test?

Answer 43

the amplitude of the tremor increases as the finger nears the target.

Question 44

How do Parkinson's patients perform in the Finger-to-Nose Test?

Answer 44

The tremor may be present at the beginning of the movement but smooth out near the target (nose)

Question 45

How do patients with essential tremor perform in the Finger-to-Nose Test?

Answer 45

the tremor is manifested throughout the test, possibly worsening as the finger approaches the target (nose).