T2 L8 Basal ganglia

Question 1

What are the levels of hierarchy of motor control?

Answer 1

High
Middle
Low

Question 2

Describe the high level of motor control

Answer 2

Function: strategy
Structures: neocortex & basal ganglia

Question 3

Describe the middle level of motor control

Answer 3

Function: tactics
Structures: motor cortex, cerebellum

Question 4

Describe the low level of motor control

Answer 4

Function: executive
Structures: brainstem, spinal cord

Question 5

What makes up the pallidum?

Answer 5

Globus pallidus interna and globus pallidus externa

Question 6

What makes up the caudate striatum?

Answer 6

Caudate nucleus & lentiform nucleus (putamen & pallidus)

Question 7

What makes up lentiform nucleus?

Answer 7

Putamen and pallidus

Question 8

What divides the corpus striatum?

Answer 8

Internal capsule

Question 9

What is the internal capsule?

Answer 9

White matter of ascending and descending tracts

Question 10

What makes up the neostriatum?

Answer 10

Caudate nucleus and putamen

Question 11

What are the 4 basal ganglia loops?

Answer 11

Motor loop
Occulomotor loop
Prefrontal loop
Limbic loop

Question 12

Describe the direct pathway

Answer 12

Cortex excites striatum –> inhibits GPi –> no signal produced so thalamus excites cortex

Question 13

What is the function of the direct pathway?

Answer 13

To promote movement

Question 14

Describe the indirect pathway

Answer 14

Cortex excites striation –> inhibits GPe –> no signal produced so STN excites GPi –> inhibits thalamus –> cortex is inhibited

Question 15

What is the function of the indirect pathway?

Answer 15

Inhibit movement

Question 16

What is the function of the hyperdirect pathway?

Answer 16

Pause movement

Question 17

Describe the hyperdirect pathway

Answer 17

Cortex excites STN –> excites GPi –> inhibits thalamus –> no signal produced so cortex is inhibited

Question 18

How does striatum know if a motor plan is to be promoted or prevented?

Answer 18

2 populations of striatum cells with specialised dopamine receptors

Question 19

What does dopamine do to direct D1?

Answer 19

Ramps up excitation of medium spiny neurons

Question 20

What does dopamine do to indirect D2?

Answer 20

Dampens down excitation of medium spiny neurons

Question 21

What does acetylcholine do to direct D1?

Answer 21

Dampens down excitation of medium spiny neurons

Question 22

What does acetylcholine do to indirect D2?

Answer 22

Ramps up excitation of medium spiny neurons