Basal ganglia and diencephalon

Question 1

What makes up the striatum?

Answer 1

Caudate and putamen

Question 2

What divides the caudate and putamen?

Answer 2

Internal capsule

Question 3

Where does the globus pallidus lie?

Answer 3

Medially to the putamen

Question 4

Where does the STN lie?

Answer 4

Beneath the thalamus, above SN of midbrain

Question 5

Where is the tail of caudate?

Answer 5

Beneath the putamen lateral to the thalamus

Question 6

Where is the BG input?

Answer 6

Cortex to striatum

Question 7

Where is the BG output?

Answer 7

Ascending GPi and SNr to thalamus

Descending GPi and SNr to upper brainstem

Question 8

What neurons give the cortical input?

Answer 8

Medium spiny neurons

Question 9

What type of neuron are MSNs?

Answer 9

Glutaminergic

Question 10

Where does the striatum fire to?

Answer 10

Direct pathway: from striatum → SNr/GPi

Indirect pathway: from striatum → GPe → STN → SNr/GPi

Hyper-direct pathway: from cortex to STN (bypasses striatum)

Question 11

What neurons are striatum projections?

Answer 11

GABAergic (inhibitory)

Question 12

What are the two types of striatal projection neurons?

Answer 12

D1: Enriched in dopamine D1- receptors, substance P, dynorphin opioid

D2: Enriched in dopamine D2 receptors, A2A receptors, enkephalin opioid

Question 13

When there is no striatal input how do SNr/GPi fire?

Answer 13

Tonically to inhibit the thalamus

Question 14

When striatal input is stimulated how is motor programme released?

Answer 14

GABAergic inputs cause SNr/GPi to cease firing, disinhibition of the thalamus - motor programme released

Question 15

What important ascending pathway is part of the basal ganglia?

Answer 15

Nigrostriatal dopamine input: From SNc to striatum (MSN)

Question 16

How does the direct pathway affect thalamocortical relay?

Answer 16

Cortex excites striatum through glutaminergic

Striatal output inhibits SNr/GPi and so reduces GPi inhibition on thalamus → Disinhibition of thalamocortical relay

Overall, it facilitates movement

Question 17

Direct pathway…

Answer 17

Facilitates movement

Question 18

How does the indirect pathway affect thalamocortical relay?

Answer 18

Cortex excites striatum through glutaminergic

Striatal output inhibits GPe and so reduces GPe inhibition of STN.

Increased activity in STN excites GPi so increases GPi inhibition on thalamus → Inhibition of thalamocortical relay

Overall, it inhibits movements

Question 19

What neurons does the STN give off?

Answer 19

Glutaminergic

Question 20

Indirect pathway…

Answer 20

Inhibits movement

Question 21

What is dopamines effect on the direct pathway?

Answer 21

D1 DA receptors on direct striatal projections facilitate pathway

And so, dopamine facilitates movement

Question 22

What is dopamines effect on the indirect pathway?

Answer 22

D2 DA receptors on indirect striatal projections inhibit pathway

Inhibits the inhibition of movement –> facilitates movement

Question 23

The movement disorder typically associated with Parkinson’s disease

Answer 23

Rigidity, hypokinetic

Question 24

The movement disorder typically associated with degenerative lesions of the striatum..

Answer 24

Huntington’s

Choreiform movements

Question 25

At a cellular level vascular lesions of the subthalamic nucleus results in

Answer 25

Loss of glutaminergic input to the globus pallidus internal segment

Question 26

In Parkinson’s disease the major site of dopaminergic cell loss is the

Answer 26

SNc

Question 27

The major drug therapy for Parkinson’s disease is L-DOPA which can

Answer 27

Enhance DA production by remaining DA neurons

Question 28

Ballism is caused by…

Answer 28

Damage to the STN