Topography of movement-related cortical potentials is abnormal in Parkinson's disease.

We studied the scalp-recorded, movement-related cortical potentials occurring immediately before and after the onset of movement in 5 patients with asymmetric Parkinson's disease. The topographic distribution of the initial slope of motor potential (isMP) was diffuse for voluntary finger movements of the more affected hand but normal for movements of the less affected hand. The frontal peak of motor potential (fpMP) was located more posterior in patients than in normal subjects. The peak amplitudes of the potentials were normal in all patients. The topographic abnormalities might reflect inadequate excitatory activity from the basal ganglia to the primary motor cortex and the supplementary motor area.