Basal Ganglia

Question 1

What are the 4 functions of the basal ganglia

Answer 1

Subconscious planning, execution of motor function

Postural control

Complex unconscious, semi voluntary mv control

Non motor role via frontal lobe

Question 2

Describe the groups of nuclei in the basal ganglia

Answer 2

Corpus striatum = striate nuclei + lentiform nuclei

Striate nuclei

• Caudate
• Putamen

Lentiform nuclei

• GP
• Putamen

Midbrain
-substancia nigra

Under thalamus
-subthalamic nuclei

Question 3

Describe the direct pathway

What is the function of the direct pathway

Answer 3

Cortex
(Glu)
Putamen
(GABA)
GP int
(GABA)
Thalamus 
(Glu)
Cortex

Double inhibition => net excitation of cortex with glutamate => MOVEMENT

Question 4

Describe the indirect pathway

What is the function of the indirect pathway

Answer 4

Cortex
(Glu)
Putamen
(GABA)
GP ext
(GABA)
STN
(Glu)
GP int
(GABA)
Thalamus 
(Glu)
Cortex

Triple inhibition => net inhibition of cortex with less glutamate => NO MOVEMENT

Question 5

What is the role of dopamine
How is its function altered by receptors

How does this affect movement

Answer 5

D1 => stimulatory
D2 => inhibitory

D1 stimulated in the direct pathway => net increase in glutamate
D2 stimulated in indirect pathway => net increase in glutamate

Indirect pathway inhibited so MOVEMENT IS INITIATED

Question 6

What is the pathophysiology behind Parkinsons

What are the key symptoms

Answer 6

Insufficient dopamine => less glutamate released onto cortex

Shuffling Parkinsonian gait
Difficulty turning
No swinging of arms when walking