Week Ten - Motor Systems

Question 1

How does the motor system work?

Answer 1

High level association areas (determine plans, goals of particular movement) interact with lower levels in the system that executes the motor commands and tell us whether the desired movement was achieved.

Question 2

What are the 3 governing principles of the motor system?

Answer 2

1) Hierarchical and parallel organisation
2) Sensory input guides output (eg using info from receptors in muscles)
3) Nature and locus of control change with learning (thing can typically require conscious management become automatic as we learn)

Question 3

What are the 2 major subcortical structures of the Motor System?

Answer 3

Basal Ganglia

Cerebellum

Question 4

How do muscles work?

Answer 4

In agonistic pairs - they act under tension

Question 5

What is the combination of an alpha motor neuron and muscle fibres referred to as?

Answer 5

Motor units

Question 6

Muscles that we really need fine control over have?

Answer 6

Few muscle fibres in the muscle unit

Question 7

Muscles that we don’t have fine control over have?

Answer 7

Many muscle fibres

Question 8

Can you grade the amount of force that comes from a motor unit?

Answer 8

NO. they are either all or nothing

Question 9

What are the 2 types of sensory receptor organs within the tendons and muscles?

Answer 9

Golgi Tendon Organs

Muscle Spindles

Question 10

What are Golgi Tendon Organs?

Answer 10

They are embedded in tendons which connect muscle to the bone.
They deterch muscle tension

Question 11

What are Muscle Spindles?

Answer 11

They are embedded in muscle tissue and detect changes in muscle length. They have their own muscle control system

Question 12

Simple reflexes are controlled by?

Answer 12

Circuits in the spinal cord

Question 13

A withdrawal reflex is not what?

Answer 13

Monosynaptic (does not provide direct communication between sensory and motor neurons innervating the muscle)

Question 14

Explain the response of the body during a stretch flex

Answer 14

This is monosynaptic (direct communication between sensory and motor neurons innervating the muscle does occur)

Question 15

How is the basal ganglia involved in motor control?

Answer 15

Once behaviours move away from higher order processing (become more automatic) it transfers to the BG

Question 16

3 divisions in the Cerebellum?

Answer 16

Neocerebellum (outer layers & motor planning)
Spinocerebellum
Vestibulocerebellum (balance)

Question 17

What happens if damage to the Cerebellum?

Answer 17

Problems adapting to novel situations. Movements can be too large or small and balance problems

Question 18

Secondary motor areas (area 6) roles?

Answer 18

Takes signals from higher areas

Involved in the planning of movements and coordinating more complex ones

Question 19

What is not required for action?

Answer 19

Sensory feedback (monkey experiment)

Question 20

What is enpoint control?

Answer 20

The idea that movements are planned based on the final goal of the movement (not planning how to get there)

Question 21

What do motor movements code for?

Answer 21

1) movement direction

2) muscle activity

Question 22

What does a population vector provide?

Answer 22

Provides cortical representation of a movement

Question 23

How can population vectors be used to control things in the human world?

Answer 23

Can control prosthetic limbs through brain activation patterns
Can control computer games

Question 24

The basal ganglia is important for?

Answer 24

Movement and mediating response competition

Question 25

Explain the Direct and Indirect pathways into the BG?

Answer 25

Direct: The accelerator. Inhibits the BG, thus there is less output onto the thalamus and greater drive to the Cortex.

Indirect: Applies the breaks. Excites the BG, thus BG has a greater inhibitory output onto the thalamus and less cortical drive

Question 26

What happens if the direct and indirect pathways of the BG aren’t in balance?

Answer 26

Parkinson’s disease
Huntington’s disease

can be out of balance in both ways

Question 27

BG problems affect what?

Answer 27

Amplitude control

Makes switching between tasks difficult

Question 28

Dopamine and its role in learning motor skills?

Answer 28

Destroyed dopaminergic neurons in rats inhibited them from learning (they were not able to learn)

Once a dopamine injection, they were able to learn.
Suggesting dopamine is required for learning rather than consolidation

Question 29

TMS and its effect on learning

Answer 29

TMS can be used to increase/decrease brain region activity

Motor cortex depressed through TMS - you do not get as much learning

Question 30

What does movement adaptation require?

Answer 30

The same goals but different motor commands

Question 31

Why does movement adaptation occur?

Answer 31

Due to error signals that are created through forward models (networks in the brain the predict the sensory consequences of a movement)