BIOL 1013 Lecture Notes - Indirect Pathway Of Movement, Substantia Nigra, Primary Motor Cortex
Document Summary
Function of basal ganglia is to initiate and control force and speed of movements. Basal ganglia is made of striatum (caudate nucleus, putamen, ventral striatum) and globus pallidus (internal and external segments) The subthalamic nucleus and substantia nigra are closely associated with the basal ganglia. A model for functional basal ganglia circuitry cortex putamen. Note that the top line, the direct pathway, is really a loop (sma, pma are in cortex) The bottom loop is the indirect pathway. The model is really in how the substantia nigra (snpc) is connected: d1 dopamine receptors facilitate glu receptors and d2 reduce glu receptor strength. The model helps explain certain diseases of the basal ganglia. Parkinson"s disease: snpc degenerates, overexcitation of indirect pathway compared to direct pathway, inhibition of va and characteristic hypokinetic nature (poverty of movement) Huntington"s disease: loss of axons to gpe, disinhibition of va, and characteristic hyperkinetic nature (choreiform or involuntary dancing movements)