Basal Ganglia Anatomy and Pharmacology

Question 1

Aims

Answer 1

1. To introduce the neuronal pathways that form the basal ganglia motor loop and the neurotransmitters they utilise.
2. To describe how the basal ganglia control movement with emphasis on the importance of dopamine.
3. To consider the different sites available for pharmacologically modulating dopamine transmission (synthesis, storage, and target receptors).

Question 2

What 2 structures in the brain make up the striatum?

Answer 2

• Putamen

- Caudate nucleus

Question 3

What structures make up the components of the Basal ganglia motor circuit?

Answer 3

• Subthalamic nucleus
• Substantia Nigra
• Hypothalamus
• Thalamus
• Putamen
• Caudate nucleus
• Globus pallidus (interior and exterior segments)

Question 4

What pathway is Acetylcholine used?
Where does it act on?
Is it executory or inhibitory?

Answer 4

• Striatal interneurons
• M1 receptors
• Excitation

Question 5

What pathway is Dopamine used?
Where does it act on?
Is it executory or inhibitory?

Answer 5

• Nigrostriatal pathway
• D1 receptors: Excitation
• D2 receptors: Inhibitory

Question 6

What pathway is GABA used?
Where does it act on?
Is it executory or inhibitory?

Answer 6

• Many projection neurones including: Striatal output pathways; thalamic output pathways
• Inhibition (GABA-A or GABA-B receptors)

Question 7

What pathway is Glutamate used?
Where does it act on?
Is it executory or inhibitory?

Answer 7

• Many projection neurones including: corticostriatal pathway, thalamocortical pathway
• Excitation (AMPA, NMDA or Kainate receptors)

Question 8

What is the primary role of the basal ganglia?

Answer 8

• Control of movement

Question 9

Activation of direct basal ganglia pathway facilitates what?

Answer 9

• Movement

Question 10

Activation of indirect basal ganglia pathway inhibits what?

Answer 10

• Movement

Question 11

Does glutamate promote or inhibit movement? / which pathway(s) direct or indirect does glutamate excite?

Answer 11

• Both

When movement is desired, inputs to basal ganglia (glutamate) from premotor cortex produce conflict in messages since both the direct and indirect pathways are activated by glutamate.

Question 12

Does Dopamine promote or inhibit movement? / which pathway(s) direct or indirect does glutamate excite?

Answer 12

• It promotes movement by exciting the direct pathway via D1 receptors and inhibits the indirect pathway via D2 receptors.
• Substantia nigra inputs (dopamine) permit movement to occur since while dopamine activates the direct pathway (via D1 receptors), it inhibits the indirect pathway (via D2 receptors)
• Dopamine is therefore critical to ensuring proper movement control.

Question 13

Watch lecture from 20:00 to see slides about the full pathway and how it works only 10mins long worth watching

Answer 13

Could turn into FC when you have time and can be bothered

• main point is dopamine activates direct and inhabits indirect pathways so facilitates movement.