CHANGES IN CEREBRAL-ACTIVITY PATTERN DUE TO SUBTHALAMIC NUCLEUS OR INTERNAL PALLIDUM STIMULATION IN PARKINSONS-DISEASE

High-frequency electrical stimulation of the internal pallidum (GPi) o r the subthalamic nucleus (STN) improves clinical symptoms of Parkinso n's disease. In 12 parkinsonian patients, G with STN and G with GPi st imulators, we used (H2O)-O-15 positron emission tomography to evaluate whether changes in movement performance were accompanied by change in regional cerebral blood flow (rCBF). Patients were scanned both at re st and while performing a free-choice joystick movement, under conditi ons of effective and ineffective electrostimulation. During effective STN stimulation, movement-related increases in rCBF were significantly higher in supplementary motor area, cingulate cortex, and dorsolatera l prefrontal cortex (DLPFC) than during ineffective stimulation. No si gnificant change was observed in any of these areas during GPi stimula tion. The difference between the effect of STN and GPi stimulation on movement-related activity was mainly localized to DLPFC. These results confirm the dominant role of nonprimary motor areas in the control of movement in parkinsonian patients and demonstrate the importance of S TN input in the control of these areas.