Basal Ganglia

Question 1

Function of Basal Ganglia

Answer 1

The Supervisor - regulates UMN activity

Question 2

Structures that make up the Subcortical Loop

Answer 2

Caudate, Putamen, Globus Pallidus.
Substantia Nigra Pars Compacta & Pars Reticulata.
Subthalamic Nuclei.

Question 3

Direct pathway function

Answer 3

Green light - releases UMNs from tonic inhibition

Question 4

Indirect pathway function

Answer 4

Brakes - increases tonic inhibition

Question 5

Input zone

Answer 5

Corpus Striatum (Caudate + Putamen)

Question 6

Corpus Striatum receives projections from

Answer 6

1. Cortex (Corticostriatal Pathway).

2. SNpc (Nigrostriatal Fibers).

Question 7

Medium Spiny N (from the Striatum) project to

Answer 7

Globus Pallidus

SNpr

Question 8

Output zones

Answer 8

Globus Pallidus

SNpr

Question 9

Striatum releases

Answer 9

GABA (inhibitory)

Question 10

Direct pathway: which Dopamine receptor? Excitatory or inhbitory?

Answer 10

D1 excitatory

Question 11

Indirect pathway: which Dopamine receptor? Excitatory or inhbitory?

Answer 11

D2 inhibitory

Question 12

Hemiballismus

Answer 12

Violent uncontrolled movements (unilateral).

Damage to contralateral Subthalamic Nuclei - UMNs receive less tonic inhibition.

Question 13

4 Cardinal Signs of Parkinsons

Answer 13

1. Tremor
2. Rigidity
3. Akinesia
4. Posture changes

Question 14

Parkinsons: posture & gait

Answer 14

Stooped over, arms flexed.

No arm swing, shuffles, unable to stop.

Question 15

Parkinsons: Cogwheel Rigidity

Answer 15

segmental, jerky motions

Question 16

How does Parkinson’s affect the direct pathway?

Answer 16

Decreased inputs from SNpc to Caudate/Putamen.
Less inhibition to GPI (so GPI more active).
More inhibition to Thalamus.
Decreased excitatory output from Thalamus to Cortex.

Question 17

How does Parkinsons affect the indirect pathway?

Answer 17

Decreased inputs from SNpc to Caudate/Putamen.
More inhibition to GPE (so GPE less active).
GPE no longer sending inhibitory signals to Subthalamic Nuclei (so Subthal more active).
Subthalamic Nuclei sends more excitatory to GPI (so GPI more active).

Question 18

Huntington’s Disease

Answer 18

Inappropriate motor activity - “choreiform” movements.
Genetic disease, gradual onset, atrophy of C+P.
Bilateral s/s.

Question 19

How does Huntington’s affect the pathway?

Answer 19

C+P send less inhibitory to GPE (so GPE more active).
GPE sends more inhibitory to Subthalmic & GPI (both less active).
Subthalamic sends less excitatory to GPI (continues making it inactive).
GPI no longer inhibiting Thalamus (so Thalamus hyperactive).
Thalamus increases excitatory output to Cortex.