Control of Movement (3)

Question 1

What are the roles of the cerebellum in movement?

Answer 1

Timing - affects control of agonist and antagonist muscles
Motor learning - strengthens input-output connections
Coordination - coordinates muscle activity in multiple joints - compares intended and executed movements

Question 2

What are the inputs to the cerebellum?

Answer 2

Mossy fibres

Climbing fibres

Question 3

Where do the mossy fibres into the cerebellum originate and what types of information do they relay?

Answer 3

Spinal cord - proprioceptive
Pontine nuclei - cortical info. and copies of motor commands before carried to spinal cord
Reticular nuclei - ascending and descending info.

Question 4

What is the general structure of cerebellar circuitry?

Answer 4

Mossy fibres synapse onto granule cells - send parallel fibres to Purkinje cells
Climbing fibres from inferior olive in brainstem - synapse onto Purkinje cells - involved in learning

Question 5

What are the output cells of the cerebellum and what is their effect?

Answer 5

Purkinje cells

Inhibitory

Question 6

What are the roles of the basal ganglia in movement?

Answer 6

Movement control

Postural maintenance

Question 7

In which layer of the cerebral cortex do the corticospinal tracts originate?

Answer 7

Layer 5

Question 8

In what way is there task dependence of corticomotor neuron firing in the motor cortex?

Answer 8

Precision grip - increased firing

Power grip - low level firing - no increase

Question 9

What are the 4 main motor cortical areas?

Answer 9

Supplementary motor area
Premotor cortex
Cingulate motor area
Primary motor cortex

Question 10

What are the role of the SMA?

Answer 10

Reciprocal connections with basal ganglia

Planning learned movement sequences

Question 11

What is the role of the premotor cortex?

Answer 11

Receives inputs from cerebellum
Planning visually-guided movements
Bilateral hand movements
Movements depending on visual cues

Question 12

What is the role of the cingulate motor area?

Answer 12

Imagined movements

Signal-triggered movements

Question 13

What is the role of the primary motor cortex?

Answer 13

Controlling muscle groups

Question 14

What is the evidence for the involvement of the SMA in motor planning?

Answer 14

Imagined movement causes SMA activation

Executed movement causes SMA and M1 activation

Question 15

Where does the readiness potential occur before movement?

Answer 15

Motor cortex and SMA

Question 16

What are the two processing streams of the premotor cortex and what are their roles?

Answer 16

Ventral - object processing - e.g. shape, size, colour

Dorsal - spatial processing - e.g. location, movement, spatial relations

Question 17

Do all of the corticospinal projection neurons originate in M1?

Answer 17

No

Question 18

What is the role of the ipsilateral corticospinal tract fibres?

Answer 18

Fractionated movements - e.g. independent finger movements

Question 19

What are the roles of the corticospinal tracts?

Answer 19

Descending control of afferent inputs - synapses onto alphaMNs and interneurons in spinal cord
Gating and gain control of spinal reflexes
Direct and indirect MN excitation
Dextrous movements