The neostriatal mosaic: multiple levels of compartmental organization in the basal ganglia.

effects behavior. Most notable among these effects are those related to the voluntary control of movement, which is compromised by neurodegenera­ tive diseases that involve the basal ganglia. Two such diseases, Parkinson's disease and Huntington's chorea, display a spectrum of movement impair­ ment (Albin et al 1989). Parkinson's disease, which results in the degener­ ation of dopaminergic systems in the basal ganglia, produces a disability to initiate desired movements. On the other hand, Huntington's chorea, which results in the degeneration of the major projection neurons of the basal ganglia, is characterized by uncontrolled movements. The complexity of these and other disorders that accompany basal ganglia dysfunction suggest its broad role in the subtlest components of voluntary movement. That memory, motivational, and emotional aspects of movement behavior are affected by this neural system is related to the fact that the striatum, which is the principal component of the basal ganglia, receives inputs from virtually all cortical areas (Carman et al 1965; Kemp & Powell 1970; Webster 1961), including limbic-related areas (Heimer & Wilson 1975). How the striatum processes cortical inputs is central to the function of the basal ganglia.