Exam 3: Motor control circuits: basal nuclei

Striatum is made up of

Caudate nucleus, putamen

Caudate nucleus function

planning executing movements, procedural learning and memory

Putamen function

motor control habit formation

Globus pallidus parts

Pars Externa and interna

Pars externa (GPe) function

input from striatum, inhibits unwanted movement

Pars interna (GPi) function

output to thalamus

Substantia Nigra parts

Pars compacta, reticulata

pars compacta function (SNc)

produces dopamine, output to striatum

pars reticulata

input from striatum, output of basal ganglia

Subthalamic nuclei STN

gets input from GPe sends to GPi and SNr

D1 receptors

direct pathway, activates movement

D2 receptors

indirect pathway, no movement, default, reduces sensitivity of neuron

What does dopamine do to the pathways

inhibit D2 and activate D1

Indirect pathway

inhibit STN to activate GPi to hit breaks harder

Direct pathway

Dopamine excites neuron to disinhibit thalamus

Parkinson disease definition

hypokinetic basal nuclei disorder

Cause of parkinsons

degen of dopaminergic neurons, less dopamine synthesis

Huntington's disease definition

hyperkinetic basal nuclei disorder, loss of control of movements

Cause of huntingtons disease

polyglutamine expansion in Huntingtin gene

Early Huntington's disease

degen of MSNs in striatum activates direct pathway

Late huntington's disease

impacts indirect also