Anatomy and function of the basal ganglia

Question 1

Areas of the brain associated with strategy

Answer 1

• Association areas of neocortex and basal ganglia

Question 2

Areas of the brain associated with tactics

Answer 2

• Motor cortex

- Cerebellum

Question 3

Areas of the brain associated with execution

Answer 3

• Brainstem

- Spinal cord

Question 4

What forms the lentiform nucleus

Answer 4

• Putamen

- Globus pallidus

Question 5

Location of lentiform

Answer 5

• lateral to thalamus

Question 6

What does the corpus striatum consist of

Answer 6

• Basal ganglia

- Internal capsule

Question 7

Main components of the basal ganglia

Answer 7

• Ventral striatum
• Dorsal striatum
• Globus pallidus
• Ventral pallidum
• Substantia nigra
• Subthalamic nucleus

Question 8

Components of the ventral striatum

Answer 8

• NAcc

- Olfactory tubercle

Question 9

What does the pallidum refer to

Answer 9

• Consists of a large structure called globus pallidus together with a smaller ventral extension called the ventral pallidum

Question 10

What can the globus pallidus be divided into

Answer 10

• GPe

- GPi

Question 11

What is the lateral geniculate body

Answer 11

• Is a relay centre in the thalamus for the visual pathway - receives a major input from the retina

Question 12

What is the dorsal striatum also known as

Answer 12

• Neostriatum
• Motor striatum
• Caudate + putamen

Question 13

What is the corpus striatum divided by

Answer 13

• Divided by internal capsule white matter of ascending and descending tracts

Question 14

How does the basal ganglia interact with the cortex

Answer 14

Basal ganglia –> Thalamus –> Cerebral cortex

Question 15

General steps of any basal ganglia loop

Answer 15

1) Cortical input
2) Striation
3) Pallidum
4) Thalamus
5) Cortical targets

Question 16

Motor loop steps

Answer 16

1) Motor, premotor, somatosensory cortex
2) Putamen
3) Lateral globus pallidus, internal segment
4) Ventral lateral and ventral anterior nuclei
5) Primary motor, premotor, supplementary motor cortex

Question 17

Direct pathway

Answer 17

Cortex –ex–> Striatum –in–> GPi –in–> thalamus –ex–> cortex

Question 18

What does activation of the direct pathway promote

Answer 18

• Movement

Question 19

Indirect pathway

Answer 19

Cortex –ex–> Striatum –in–> GPe –in–> STN –ex–> GPi –in–> thalamus –ex–> cortex

Question 20

What does the activation of the indirect pathway do

Answer 20

• Withold movement

Question 21

Hyperdirect pathway

Answer 21

Cortex –ex–> STN –ex–> GPi –in–> thalamus –ex–> cortex

Question 22

What does the activation of the hyperdirect pathway do

Answer 22

• Pauses movement

Question 23

Effect of thalamus inhibition on movement

Answer 23

• Prevents movement

Question 24

Effect of reducing inhibition of thalamus on movement

Answer 24

• Reducing inhibition of thalamus facilitates movement

Question 25

What is dopamine released by

Answer 25

- Released by the substantia nigra

Question 26

What are the two populations striatum neurons

Answer 26

Striatum medium spiny neurons with specialised dopamine receptors 1) Direct D1 2) Indirect D2

Question 27

Effect of DA on direct D1 neurons

Answer 27

- DA ramps up MSN excitation

Question 28

Effect of DA on indirect D2 neurons

Answer 28

- DA dampens down MSN excitation

Question 29

What interneurons are present in the striatum

Answer 29

- Striatum interneurons that use ACh | - ACh opposes effects of DA

Question 30

What does ACh tip the balance of pathways towards

Answer 30

- tips pathways towards prevention of movement

Question 31

What is the balance of movement activity based on

Answer 31

- The balance of activity between the 2 medium spiny neuron spiny neuron populations determines the likelihood of movement taking through the direct and indirect pathways - This balance is regulated by dopamine and ACh and influenced by the cortical inputs to the striatum