Movement Disorders

Question 1

Dopamine neurons are located in the ____ and their axon terminal are located in ____.

Answer 1

• located in substantia nigra pars compacta (SNc)
• project to striatum (caudate+putamen)
• pars reticulata does not contain many DA neurons, and it projects to GP which receives some but not many DA neurons

Question 2

Two types of neurons in stiatum

Answer 2

1. Spiny/Projection neurons - smaller, use GABA as NT; 2 subtypes intertangled in the striatum: ENK (inhibit) and SP (initiate)
2. Aspiny/interneurons - larger, use GABA as NT; there are 4 types: cholinergic, parvalbuminergic, somatostainergic, and calretinergic

Question 3

ENK vs. Substance P spiny neurons in striatum

Answer 3

1. ENK - inhibit movement
   - D2 receptors
   - GABA as NT
   - to GPe (e for eNK)
   - indirect pathway to inhibit movements
2. SP - initiate movement
   - D1 receptors
   - GABA as NT
   - to GPi –> initiate limb movement
   - SNc –> regulating DA neurons
   - SNr –> initiate head/eye movement
   - direct pathway
   + SP neurons also contain dynorphin

Question 4

Cholinergic interneurons in striatum

Answer 4

• big soma
• to spiny neurons
• ACh as NT
• opposes DA action on projection neurons

Question 5

Parvalbuminergic interneurons in striatum

Answer 5

• big soma
• to spiny neurons
• GABA as NT
• contains parvalbumin (Ca BP)
• inhibits projection neurons, sharpens activity
• the only interneuron lost in HD

Question 6

Somatostatinergic interneurons in striatum

Answer 6

• small somas
• projection unclear
• GABA as NT, also NO
• contains somatostatin and NPY

Question 7

Calretinergic interneurons in striatum

Answer 7

• small soma
• projection unclear
• GABA as NT
• contains calretinin (Ca BP)

Question 8

Targets of globus pallidus

Answer 8

GPe –> STN

GPi –> motor thalamus which is VA + VL (VL has caudalis and oralis parts)

Question 9

Inputs to motor thalamus (VA/VL)

Answer 9

• GPi

- SNr

Question 10

Basal ganglia sends output to where?

Answer 10

motor-related cortex

GPi to motor thalamus to motor cortices

Question 11

Inputs to the striatum

Answer 11

• cerebral cortex (main input, almost all cortical projections leave from layer 5 and go to striatum)
• SNc (dopaminergic)
• intralaminar thalamus (not well defined)

Question 12

Synaptic targets of input to striatum (where do they land?)

Answer 12

• cortex –> spine tips (Glutamate)

- SNc –> spine sides (DA)

Question 13

Inputs to globus pallidus

Answer 13

• Striatum, ENK neurons –> GPe
• Striatum, SP neurons –> GPi
• STN –> GPi
  These inputs intertwine together on the spines of the projection neurons

Question 14

Describe the BG Indirect pathway:

Answer 14

• Putamen to GPe [GABA]
• GPe STN [GABA]
• STN to GPi/SNr [excitatory]
• GPi/SNr to VA/VL [GABA]

Question 15

Describe the BG Direct pathway:

Answer 15

• Putamen to GPi/SNr [GABA]

- GPi/SNr to VA/VL [GABA]