Motor control

Question 1

How did Penfield construct the somatotopic map of the body?

Answer 1

• By stimulating primary motor cortex during surgery for epilepsy
• Hands, feet and the mouth are very overrepresented

Question 2

Apart from the motor cortex, what other area of the brain is responsible for coordinating movement?

Answer 2

cerebellum

- has more neurons than the cortex

Question 3

What is the role of the cerebellum in coordinating movement?

Answer 3

• Computes the contributions of muscles

- Projects via the ventrolateral thalamus back to the motor cortex, allowing current movements to be modified

Question 4

What is the result of damage to the cerebellum

a) Flocculondular/vermis
b) Intermediate zone
c) Lateral zone

Answer 4

a) posture & balance problems
b) limb rigidity
c) weakness and decomposition of movement

Question 5

What is the role of the supplementary motor area?

Answer 5

• Motor planning
• Responds to specific parts of a learned sequence
• Stimulation produces involuntary movement

Question 6

What are mirror neurones?

Answer 6

Neurons that respond both to the performing of an action and the sight of someone carrying out an action

Question 7

What are the 3 possible functions of mirror neurons?

Answer 7

1. Immitation
2. Understanding the actions of others
3. Encoding intention?

Question 8

How is mirror neuron activity influenced by autism?

Answer 8

• children with autism have lower mirror neuron activity in the ventral premotor cortex when imitating facial expressions
• level of activity corresponds to level of autism severity

Question 9

What is limb apraxia?

Answer 9

• Inappropriate limb movement in response to commands
• Caused by damage to left frontal/parietal cortex
• Can also have lesions in left ventral premotor cortex, producing inability to understand other people’s gestures

Question 10

What is constructional apraxia?

Answer 10

• Inability to perceive/imagine geometric shapes

- Caused by damage to right parietal cortex