HUMAN SUPPLEMENTARY MOTOR AREA IS ACTIVE IN PREPARATION FOR BOTH VOLUNTARY MUSCLE-RELAXATION AND CONTRACTION - SUBDURAL RECORDING OF BEREITSCHAFTSPOTENTIAL

Bereitschaftspotentials (BPs) preceding muscle relaxation and contract ion were compared by using subdural electrodes which were implanted on to the right medial frontal surface in two patients with supplementary motor area (SMA) seizure. The applied movement paradigm (muscle relax ation and contraction tasks) was completely the same as employed in ou r previous study [Terada, K., Ikeda, A., Nagamine, T. and Shibasaki, H ., Electroenceph. clin. Neurophysiol., 95 (1995) 335-345]. In both pat ients, either negative or positive BPs were observed in the SMA-proper and supplementary negative motor area (SNMA) starting at 1.2-1.8 prio r to both movements. In one patient, BP was more widespread in the rel axation task whereas more restricted to the hand area in the contracti on task. In the other patient, the BPs were observed in the cortical a rea rostral to SNMA (pre-SMA), in addition to the SMA-proper, in both tasks. It is concluded that SMA-proper and SNMA, and probably pre-SMA as well, in humans are similarly active in preparation for both volunt ary muscle contraction and relaxation. (C) 1998 Elsevier Science Irela nd Ltd.