Components of the movement-related cortical potential and their scalp topography.

In order to clarify the significance of the various components of the movement-related cortical potentials, scalp-recorded potential changes associated with voluntary, self-paced middle finger flexion and extension were studied by an opisthochronic averaging program in 14 normal right-handed subjects. Topographical study, based on 14 simultaneously recorded and averaged EEG channels, enabled us to identify at least 8 components; 4 pre-motion and 4 post-motion. The pre-motion components are the Beretischaftspotential (BP) (a symmetric early negative shift), NS'(-500 to -90) (a negative slope maximal over the contralateral precentral region and culminating in N-90 ipsilaterally), P-50 (corresponding to the pre-motion positivity, PMP), and N-10 (probably corresponding to the motor potential, MP). The post-motion components include N+50 (a sharp negative post-motion activity over the contralateral frontal region), P+90, N+160 (presumably representing sensory functions) and P+300 (a large positivity maximal over the contralateral precentral region but widely distributed).