Pathways and Centres

Question 1

What are the functions of the basal ganglia?

Answer 1

• Provide feedback mechanisms to the cortex for initiation, control, cessation of motor responses
• Dampen cerebral cortex
• Excite cerebral cortex

Question 2

What can lesions of the basal ganglia lead to?

Answer 2

Dyskinesia

Question 3

What makes up the lentiform nucleus?

Answer 3

• Putamen

- Globus pallidus

Question 4

What makes up the striatum

Answer 4

• Caudate nucleus

- Putamen

Question 5

What does the basal ganglia contain?

Answer 5

• Lentiform
• Corpus striatum
• Amygdala

Question 6

What do the components of the basal ganglia develop from?

Answer 6

Telencephalic grey matter

Question 7

What part of the basal ganglia is located at the front of the temporal lobe?

Answer 7

Amygdala

Question 8

What does the substantial nigra contain? What do these contain?

Answer 8

• Pars compacta
• Pars reticulata (loose)
• Cells contain melanin producing dopamine

Question 9

What is the pars reticulata functionally connected to?

Answer 9

Interna globus pallidus

Question 10

What is the mechanism for the pathway of the internal circuitry of basal ganglia?

Answer 10

1) Cortex excites striatum
2) Striatum inhibits GPI&SN(PR)
3) This inhibits thalamus (turns thalamus off)
4) Thalamus excites the cortex

Question 11

How does the motor cortex influence LMNs?

Answer 11

• Directly via CS pathway

- Indirectly via connections to brainstem centres from which UMNs arise (RS pathway)

Question 12

What does the direct pathway lead to?

Answer 12

• Excitation of the cortex from the thalamus

- Facilitates ongoing movement

Question 13

What does the indirect pathway lead to?

Answer 13

• Inhibition of the cortex from the thalamus

- Inhibits unwanted movement

Question 14

What are the roles of the substantial nigra (pars compacta)?

Answer 14

• Releases dopamine
• Modulatory role in movement
• Opposing effects on direct& indirect pathways
• Gives a boost to initiate movement (does not start movement!)

Question 15

What happens if the basal ganglia is damaged?

Answer 15

• Disordered movement on contralateral side
• Tremor
• Rigidity
• Slow movement/hypokinesia, poor initiation: slow walking, little steps, cannot initiate facial expression

Question 16

What is the most common disease of the basal ganglia?

Answer 16

• Disruption of nigrostriatal input

- Parkinson’s disease

Question 17

What other degenerative changes can affect the basal ganglia circuitry?

Answer 17

• Degeneration of sub thalamic nucleus

- Degeneration of inhibitory fibres from striatum to GP

Question 18

What diseases present hypo/hyperkinetic disorders?

Answer 18

• Hypo= Parkinson’s

- Hyper= Chorea in Huntington’s