High-frequency stimulation of the subthalamic nucleus (STN) improves the motor signs of Parkinson's disease (PD). The three main components (motor, associative, and limbic) of the cortical-basal ganglia-cortical circuits pass through the STN. It is not known whether STN stimulation can influence the limbic loop. We present two PD patients in whom acute stimulation of an electrode located in the STN using high stimulation parameters (50% higher than therapeutic) induced funny associations, leading to infectious laughter and hilarity, whereas the therapeutic parameters induced a hypomanic behavior and marked improvement of akinesia. Our report suggests that the STN, with its sensorimotor, cognitive, and limbic parts is not only involved in motor, but also in psychomotor regulation.
Copyright 2001 Movement Disorder Society.