Lecture 18: Motor Cortices

Question 1

What three areas of the frontal lobe make up motor cortex?

Answer 1

1. Primary Motor Cortex
2. Premotor Cortex
3. Supplementary Motor Cortex

Question 2

Purpose of Broca’s Area

Answer 2

Activation of appropriate muscles for speech production

Question 3

Purpose of Frontal eye fields

Answer 3

Activation of extraocular muscles used in horizontal eye movements

Question 4

Another name for primary motor cortex

Answer 4

M1

Question 5

Input/Output of M1

Answer 5

Input: PMC, SMA, Primary somatosensory cortex, posterior parietal areas involved with integrating multpile sensory inputs

Output: PMC, SMA, M1 on other side of brain

Question 6

Input/Output of PMC

Answer 6

Input: M1, PMC, Posterial parietal cortex, Basal ganglia and cerebellum via VA/VL, prefrontal cortex

Output: M1, SMA

Question 7

UMNs of corticospinal and corticobulbar pathways

Answer 7

Giant Betz cells in layer 5 of motor cortex

Question 8

What part of primary motor cortex stimulates legs?

Answer 8

Medial part of contralateral M1

Question 9

Internal Capsule

Answer 9

Small space where the UMNs from primary motor cortex are condensed between the thalamus and basal ganglia

Question 10

How are the neurons in the internal capsule arranged?

Answer 10

• It is a sideways V shape looking from above
• Face is at the bend
• Arm, trunk, and limb in posterior branch

Question 11

Upper motor neuron influences

Answer 11

1. Direct cortical stimulation of spinal cord; contralaterally
2. Direct cortical stimulation of brainstem bilat. by alpha motor neurons
3. Cortex innervates rubrospinal path via corticorubral tract
4. Corticotectal tract lets cortex activate tectospinal tract
5. Corticoreticular lets cortex modulate reticulospinal
6. Interneurons may be involved

Question 12

What does the corticostriate pathway innervate?

Answer 12

Caudate nucleus and putamen of basal ganglia

Question 13

What do the corticopontine and corticoolivary tracts innervate?

Answer 13

Important inputs to the cerebellum

Question 14

Purpose of corticocortical pathways

Answer 14

Cortical areas communicate with each other; connections often go via thalamus.

May receive input from basal ganglia and cerebellum through thalamus.

Question 15

Functions of primary motor cortex

Answer 15

1. Relay motor commands to alpha motor neurons
2. Firing rate will increase with increased movement force
3. Neurons display left/right direction selectivity
4. Neurons fire in correlation with distance moved
5. Firing patters encode movement speed

Question 16

How does the premotor cortex help with movement?

Answer 16

It selects a motor plan appropriate for the situation.

Question 17

Mirror neurons of premotor complex

Answer 17

Will fire just by watching or hearing an action

Question 18

True or False: Premotor complex neurons are sensitive to the inferred intentions of a movement.

Answer 18

True

Question 19

True or False: PMC neurons cannot distinguish between correct and incorrect actions

Answer 19

False

Question 20

What does the SMA do?

Answer 20

Remembers and programs learned sequences of movements

Muscle memory

Fires while rehearsing in head beforehand

Question 21

What makes up the association cortex for motor purposes?

Answer 21

1. Prefrontal cortex
2. Posterior parietal cortex

Question 22

Role of posterior parietal cortex in movement

Answer 22

• Target objects in space
• Forms a view of the world independent of orientation
• Damage leads to apraxias of complex coordinated movements

Question 23

Role of prefrontal cortex in regards to movement

Answer 23

Decides what actions to take; executive function

Delay of instant gratification