6.1.1 Basal Ganglia

Question 1

What is the basal ganglia?

Answer 1

Collection of sub-cortical nuclei

Question 2

What nuclei make up the basal ganglia?

Answer 2

Caudate Nucleus
Globus Pallidus
Putamen

Question 3

Label the image

Answer 3

Question 4

What makes up the Lentiform nucleus?

Answer 4

Putamen and Globus pallidus

Question 5

What are the different parts of the midbrain?

Answer 5

Mickey mouse ears - cerebral peduncles connecting cerebrum to brainstem

Eyebrows - substantia nigra

Eyes - red nucleus

Tears - medial lemniscus (dorsal column 2nd order neurones to thalamus)

Nose - Edinger Westphal and Oculomotor nucleus

Mouth - Aqueduct of Sylvius with periaqueductal grey matter around

Question 6

What is the substantia niagra pars compacta?

Answer 6

SNc, source of dopamine in midbrain

Question 7

What is the striatum?

Answer 7

Caudate nucleus and putamen

Responsible for planning and modulation of movement pathways

Question 8

Describe the globus pallidus

Answer 8

Medial to the putamen
Forms the lentiform nucleus with putamen

Has an internal and external segment

Question 9

What does the basal ganglia communicate with?

Answer 9

Motor cortex via the thalamus

Increased thalamic activity causes increased cortical activity and vive.

Question 10

What is the normal function of the basal ganglia?

Answer 10

Unclear

Roles in:
- Reinforcing appropriate movements and removing inappropriate movements e.g. picking up a cup of tea- need to facilitate elbow flexion and suppress elbow extension
- Direct pathways reinforce appropriate movements (excitatory to motor cortex)
- Indirect pathway edits out inappropriate movements (inhibitory to motor cortex)
- Dopamine facilitates movement by exciting motor cortex
- Basal ganglia regulate ipsilateral motor cortex, hence if SNc is affected unilaterally will be contralateral signs due to decussation of CST

Question 11

What receptors does dopamine act on?

Answer 11

Excites direct pathway by stimulating excitatory D1 on striatal neurones in direct

Inhibits pathway by activating inhibitory D2 receptors on striatal neurones in indirect

Question 12

What receptors does dopamine act on?

Answer 12

Excites direct pathway by stimulating excitatory D1 on striatal neurones in direct

Inhibits pathway by activating inhibitory D2 receptors on striatal neurones in indirect

Question 13

Outline the parts of the basal ganglia pathway you need to know

Answer 13

Substania nigra pars compacta- SNc

Globus pallidus external segment- GPe

Globus pallidus internal segment- GPi

STN-subthalamic nucleus