MOVEMENT-RELATED POTENTIALS ASSOCIATED WITH BILATERAL SIMULTANEOUS AND UNILATERAL MOVEMENTS RECORDED FROM HUMAN SUPPLEMENTARY MOTOR AREA

To clarify the differences of movement-related potentials (MRPs) among ipsilateral, contralateral and simultaneous bilateral movements, MRPs with finger, thumb or foot movements were recorded from subdural elec trodes chronically implanted on the supplementary motor area (SMA) in 3 patients, and also from the primary sensorimotor area in two of them being evaluated for epilepsy surgery. As a result: (1) SMA generated clear pre-movement potentials regardless of the type of movement. Its amplitude was almost identical between contralateral and bilateral mov ements except for the motor potential (MP). The pre-movement potential s associated with ipsilateral movements were relatively smaller than t hose with contralateral or bilateral movements. (2) The primary sensor imotor area generated clear pre-movement potentials in contralateral a nd bilateral movements with similar amplitude. With ipsilateral hand m ovements, however, only a small Bereitschaftspotential (BP) and no neg ative slope (NS') or MP was seen, and ipsilateral foot movements were not preceded by any BP. It is, therefore, most likely that, as far as the preparation for simple voluntary self-paced movement is concerned, the SMA plays an equally important role in unilateral and bilateral m ovements, whereas the primary sensorimotor area is involved predominan tly in the preparation of contralateral movements.