Basal Ganglia

Question 1

Definition of basal ganglia

Answer 1

Collective term for a group of anatomically and functionally related subcortical nuclei.

Question 2

5 components of basal ganglia

Answer 2

 Caudate
 Putamen
 Subthalamic nucleus
 Substantia nigra
 Globus Pallidus: internal and external parts

Question 3

Basal Ganglia Function

Answer 3

• Involved in control of voluntary movements

Question 4

2 parts of the substantia Nigra

Answer 4

 SN pars Compacta: cells that release dopamine
 SN pars Reticulata: part of the basal ganglia and gives inputting information to the striatum

Question 5

Bradykinesia definition

Answer 5

• Slow movement
• Lack of voluntary movement
• Lack of associated movements (arm swing in gait)
• Lack of facial expression

Question 6

Rigidity definition

Answer 6

bidirectional increase in resistance to passive movement

Question 7

Tremor

Answer 7

Regularly alternating involuntary movements of small amplitude

Question 8

Direct pathway of stimulating and encouraging movement

Answer 8

• Idea from brain passes from cortex to striatum. Cortex would stimulate cortico-striatum neurones which are excitatory
• They would release glutamate meaning striatum-palladium neurones is stimulated. It is a inhibitory neurone meaning when it reaches the Globus pallidus (internal), it releases GABA which is inhibitory so next connection is inhibited.
• This means there is less activity from Globus Pallidus (internal) to the Thalamus. Less neurotransmitter released when it reaches thalamus meaning less inhibition occurs so the neurone from the thalamus to the cortex is excitatory and not inhibited.
• This neurone stimulates cortex to stimulate movement via corticospinal pathway or corticoreticular tract

Question 9

Indirect pathway to inhibit movement

Answer 9

• Idea from brain passes from cortex to striatum. Cortex would stimulate cortico-striatum neurones which are excitatory
• They would release glutamate meaning striatum-palladium neurones is stimulated. It is an inhibitory neurone meaning when it reaches the Globus pallidus (external), it releases GABA which is inhibitory so next connection between the Globus pallidus (external) and subthalamic nucleus is inhibited.
• The neurone does not release a lot of GABA due to its inactivity. This means the neurone between the subthalamic nucleus and Globus pallidus (internal) is excitatory. Neurone releases glutamate
• This causes increased activity of inhibitory neurone between G.pallidus (internal) and thalamus which causes an increase in the release of GABA
• Neurone that connects thalamus to cortex is inhibited. This means less stimulation to cortex and less activity from cortex and less activity to corticospinal tracts

Question 10

Dopamine role in movement

Answer 10

• Released from substantia nigra pars compacta at the midbrain
• Stimulates D1 receptors to stimulate the neurone between striatum and G. pallidus (internal) which enhances the direct pathway to create movement
• Binds to D2 receptors to inhibit indirect pathway-> inhibition of pathway that inhibits movement encourages direct pathway
• Dopamine encourages movement