Pathophysiology of Motor Dysfunction in Parkinson’s Disease as the Rationale for Drug Treatment and Rehabilitation

Figure 1

A simplified view of the functional anatomy of the basal ganglia (BG). The main input and output connections and the basic internal circuitry of the BG are shown. Here are represented the direct pathway (panel (a)), the indirect pathway (panel (b)), and the alteration of the balance between the direct and indirect pathways in Parkinson’s disease (panel (c)). Blue arrows show the excitatory glutamatergic pathways, red arrows indicate the inhibitory GABAergic pathways, and green arrows mark the dopaminergic pathway. CMA: cingulate motor area; D1: dopamine D1 receptor; D2: dopamine D2 receptor; GPe: external segment of the globus pallidus; GPi: internal segment of the globus pallidus; MC: primary motor cortex; PMC: premotor cortex; SMA: supplementary motor area; SNc: substantia nigra pars compacta; SNr: substantia nigra pars reticulata; STN: subthalamic nucleus; VA/VL: ventral anterior/ventrolateral thalamic nuclei.

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