Basal Ganglia

Question 1

What is the main function of the cerebellum?

Answer 1

Coordination and synergy.

Question 2

What is the main function of the basal ganglia?

Answer 2

Initiation, control and cessation of movement.

-provide feedback mechanism to the cerebral cortex

Question 3

What do most of the outputs from the basal ganglia go through?

Answer 3

Through the thalamus.

|&raquo_space; dampen / excite the cerebral cortex

Question 4

What can lesions of the basal ganglia lead to?

Answer 4

Dyskinesia.

-abnormal, involuntary movements

Question 5

What does the basal ganglia consist of?

Answer 5

Caudate nucleus
Lentiform nucleus (putamen and globus pallidus)
Amygdala
Claustrum
Subthalamus

Work together functionally.

Question 6

What does the basal ganglia develop from?

Answer 6

Telencephalic grey matter.

Question 7

What are the 2 functional parts of the globus pallidus?

Answer 7

Interna

Externa

Question 8

What are the 2 functional parts of the substantia nigra?

Answer 8

Pars compacta

Pars reticulata

Question 9

What is the par reticulata functionally a part of?

Answer 9

Pars reticulata is functionally a part of globus pallidus INTERNA.

Question 10

What is the looping circuit involving the basal ganglia?

Answer 10

Cerebral cortex
>> striatum (caudate and putamen)
>> globus pallidus interna and pars reticulata
>> thalamus
>> cerebral cortex

Question 11

Which motor areas of the cortex does the thalamus project information from the basal ganglia to?

Answer 11

• Premotor motor area

- Supplementary motor area

Question 12

How does the motor cortex influence LMNs? (2)

Answer 12

• DIRECTLY; via corticospinal pathway

- INDIRECTLY; via reticulospinal pathway (connections to brainstem centres&raquo_space; UMNs)

Question 13

What is the function of the direct pathway?

Answer 13

Facilitate behaviour and movements that are required and appropriate.
-leads to excitation of the cortex from the thalamus

Question 14

What is the function of the indirect pathway?

Answer 14

Inhibits unwanted behaviour and movements.

-leads to inhibition of the cortex from the thalamus

Question 15

What structures does the indirect pathway involve that the direct pathway doesn’t? (2)

Answer 15

• Subthalamus

- Globus pallidus externa

Question 16

What is the main function of the pars compacta (substantia nigra)?

Answer 16

Initiates movement.

Question 17

What does the pars compacta (substantia nigra) release?

Answer 17

Dopamine.

-has modulatory role in movement

Question 18

NB. Why does the substantia nigra appear so dark?

Answer 18

It contains melanin.

Question 19

What happens if the pars compacta (substantia nigra) is damaged?

Answer 19

Cannot initiate movement.

Question 20

What effect does the pars compacta (substantia nigra) have on the direct and indirect pathways?

Answer 20

Has opposing effects on the 2 pathways.
-e.g. if it excited the direct pathway, it inhibits the indirect pathway

NB. Indirect pathway inhibits movement, so inhibiting it removes inhibition&raquo_space; EXCITATION.

Question 21

What is the effect of basal ganglia damage?

Answer 21

Disorder movement on the contralateral side.

-not paralysis

Question 22

What disordered movements does damage to the basal ganglia cause?

Answer 22

• Hypokinesia (slow movement and poor initiation)
• Rigidity
• Tremour

Question 23

What is the most common disease of the basal ganglia?

Answer 23

Involves disruption of the nigrostriatial input&raquo_space; PARKINSON’S DISEASE.

Question 24

What does damage to the indirect pathway lead to?

Answer 24

Hyperkinetic disorder – degeneration of inhibitory fibres.

-e.g. Huntington’s

Question 25

What does degeneration of the subthalamic nucleus cause?

Answer 25

Degeneration of inhibitory fibres to the globus pallidus.

|&raquo_space; hyperkinetic disorders