Disturbance in Task Performance after Inhibition of Subthalamic Nucleus Neurons

Abstract

The subthalamic nucleus (STN) has been believed to be a key structure of the basal ganglia in the control of voluntary limb movement (DeLong, 1990; Albin et al., 1989b; Kitai and Kita, 1987; Whittier and Mettler,1949). An experimental lesion in the STN in monkeys produces violent involuntary movements of the leg and arm (Hamada and DeLong, 1992a; Carpenter et al, 1950; Whittier and Mettler, 1949). In normal subjects, however, it is not convincing that the STN plays an important role in the control of limb movement. Firing characteristics of STN neurons were studied in normal behaving monkeys (DeLong et al., 1985; Georgopoulos et al., 1983). Activity of STN neurons increased during movement, but in the majority of neurons the increase in firing begins after onset of the limb EMG. The increase in activity of STN neurons seems too late to account for movement initiation (Georgopoulos et al.,1983). Experimental lesion of the STN in normal awake monkeys (Hamada and DeLong, 1992a) provides little evidence for a significant effect of STN inactivation on voluntary movement. These findings are difficult to reconcile with the view that the STN plays an important role in the control of voluntary limb movement.