Basal Ganglia

Question 1

Describe neurotransmitters of basal ganglia

Answer 1

Dopamine:
Cell bodies: substantia nigra pars compacta
Axons travel to striatum
D1 and D2 receptors on different neurons in striatum

Cholinergic:
Cell bodies: neurons of striatum
Axons synapse on other neurons in striatum
Excitation

GABA-ergic:
Cell bodies: striatum
Axons travel to globus pallidus internal segment and substantia nigra pars reticulata
Inhibition

Question 2

Describ inputs/outputs of basal ganglia

Answer 2

Inputs: substantia nigra pars compacta receives inputs and relays them to striatum

Outputs: globus pallidus (internal segment) and substantia nigra pars reticulata send axons to thalamus
When activated, they release GABA at synapses in thalamus
Inhibition of thalamus

Question 3

Compare and contrast direct and indirect pathway, including circuitry and function

Answer 3

Direct pathway: 
To activate: SNPC sends dopamine to striatum
Dopamine binds to D1 receptors
Striatal neurons are excited
Axons release GABA in GPi and SNPR
When active -> allow motion

Indirect pathway:
To activate: cortical inputs release EAA
Striatal neurons of indirect path are excited
Axons synapse in GPe (more GABA)
GPe axons travel to subthalamic nucleus (GABA)
Axons from subthalamic nerve travel to GPi and SNPR (EAA)
When active -> inhibit motion

Question 4

Describe nuclei of basal ganlgia

Answer 4

Substantia nigra: pars compacta and pars reticulata
Striatum: caudate and putamen
Globus pallidus: external and internal segments
Subthalamic nucleus