Functional hierarchy of the motor system (and motor control)

Question 1

What are the 3 stages in motor control?

Answer 1

Strategy
Tactics
Execution

Question 2

Describe “strategy”.

Answer 2

The way by which a movement is designed to reach a specific goal

Question 3

Which parts of the brain are involved in strategy of motor control?

Answer 3

Neo-associative cortex

Basal ganglion

Question 4

Describe “tactics”.

Answer 4

The sequence of spatio-temporal muscle contractions to achieve a goal smoothly and accurately

Question 5

Which parts of the brain are involved in tactics?

Answer 5

Motor cortex

Cerebellum

Question 6

Describe “execution”.

Answer 6

Activation of motor neuron and interneuron pools to generate a goal-directed movement

Question 7

What do the lateral pathways of the spinal cord do?

Answer 7

Controls voluntary and distal movements

Question 8

What are the tracts of the lateral pathway?

Answer 8

Rubrospinal

Corticospinal

Question 9

What do the ventromedial pathways of the spinal cord do?

Answer 9

Control posture and locomotion

Question 10

What part if the brain controls the ventromedial pathways?

Answer 10

Brainstem

Question 11

What part of the brain controls the lateral pathways?

Answer 11

Under direct cortical control

Question 12

What are the tracts of the ventromedial pathways?

Answer 12

Tectospinal
Vestibulospinal
Pontine reticulospinal
Medullary reticulospinal

Question 13

What effects would a lesion of just the corticospinal tract have?

Answer 13

Loss of fine movements in arms and hands
Can no longer move shoulders, elbows, wrists or fingers independently

Function restored after a few months as rubrospinal tract takes over

Question 14

What effects would lesion affecting both the corticospinal and rubrospinal tracts have?

Answer 14

Loss of fine movements in arms and hands

Can no longer move shoulders, elbows, wrists or fingers independently

Question 15

Where do the ventromedial pathways innervate?

Answer 15

Trunk and antigravity muscles in limbs

Question 16

Where are decisions on motor control taken?

Answer 16

Prefrontal and parietal cortex?

Question 17

Describe how we “plan and prepare” for movement.

Answer 17

Decision making neurons in the pre-motor area fire 1 second before movement occurs
They fire when a movement is imagined
“Mirror neurons” fire when others perform an action

This allows us to understand and rehearse a movement

Question 18

How do we stabilise movement?

Answer 18

Change in body position initiates rapid compensatory feedback messages from brainstem vestibular nuclei to motor neurones which then corrects postural instability

Brainstem reticular formation nuclei also initiate feedforward anticipatory adjustments

Question 19

What is the corpus striatum?

Answer 19

A nucleus in the subcortical basal ganglia of the forebrain

Question 20

What are the 2 principal nuclei of the corpus striatum?

Answer 20

Caudate and putamen

Question 21

What does the caudate nucleus do?

Answer 21

Receives input before limb/trunk movement

Plays vital role in storing and processing memories

Question 22

What causes Parkinson’s disease?

Answer 22

Degeneration of neurones in substantia nigra

Question 23

What is the effect of Parkinson’s disease?

Answer 23

Hyperkinesia

Question 24

What causes Huntington’s disease?

Answer 24

Profound loss of caudate, putamen and globus pallidus

Question 25

How may Huntington’s disease present?

Answer 25

Mood swings
Clumsy/jerky movement
Problems swallowing
Difficulty concentrating
Memory lapses