Consider the brain areas and connections pictured in thesimplified basal ganglia circuit. Parkinson’s disease results fromthe degeneration of dopamine neurons in the substantia nigra parscompacta (SNc). Dopamine can inhibit or excite neurons in theputamen, a sub-division of the striatum. Describe how this damagecauses a chain of effects on activity in other basal ganglia areasand the structures they ultimately output to, and how this resultsin hypokinesia (reduced movements) in two different ways. Make sureto refer differentially to the ‘direct’ and ‘indirect’pathways.
