Electrical source localization of human movement-related cortical potentials.

Movement-related cortical potentials (MRCP) of healthy humans were analyzed with a brain electrical source analysis program for modelling equivalent electrical dipoles in order to suggest the generators of the MRCP. Both right and left voluntary self-paced index finger movements were performed by 14 subjects and MRCP were recorded on the scalp with 29 electrodes. A spatiotemporal three-dipole model was developed and it explained 94.1% of the right-hand data and 96.4% of the left-hand data. The models for right- and left-hand data were almost similar except for the different hemispheres. A midline dipole was most active during the preparatory period before the onset of voluntary movement and two contralaterally locating dipoles were most active during and immediately after the motor act. The present model did not support recently suggested bilateral activation of primary motor cortices preceding the voluntary movement. The locations, orientations and the time course of activation of the dipoles suggest the involvement of the supplementary motor area in preparation of the movement and the contralateral primary motor cortex during the execution of the movement and the contralateral primary sensory cortex following the movement.