Basal Ganglia

motor modulation

cortex → basal ganglia → thalamus → cortex

where do the basal ganglia and cerebellum receive signal from?

the cerebral cortex

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they do not directly deal w spinal cord

Striatum

putamen + caudate

putamen looks like an egg, caudate is a C shape

main components of the basal ganglia

1. caudate nucleus

2. putamen

3. globus pallidus: external and internal

4. subthalamus

5. substantia nigra

• substantia nigra pars reticulata (SNr): neuron contain GABA send to thalamus

• substantia nigra pars compacta (SNc): neuron contain dopamine and send to striatum

direct pathway

pro movement

SNc releases dopamine → activates the D1 receptors @ striatum → inhibit the indirect pathway thru D2 receptor → excite the thalamus

indirect pathway

anti movement

NO dopamine from SNc → inhibit the thalamus

Parkinson’s disease

indirect pathway

degeneration of the SNc → inhibit thalamus → difficulty w initiate movement

Hemibolism

indirect pathway problem

result from a stroke → subthalamic nucleus is affected → inhibition process is damaged → involuntary movement

Huntington’s disease

caudate and putamen degeneration - genetic disorder

early stage: affect indirect pathway → uncontrolled movement

later stage: affect direct pathway → movements slow down (Parkinson’s like symptom)