BOTH PRIMARY MOTOR CORTEX AND SUPPLEMENTARY MOTOR AREA PLAY AN IMPORTANT ROLE IN COMPLEX FINGER MOVEMENT

In order to clarify the roles played by the primary motor cortex and t he supplementary motor area in the execution of complex sequential and simple repetitive finger movements, regional cerebral blood flow (rCB F) was measured with PET using O-15-labelled water in five normal subj ects. The PET data of each individual subject co-registered to his own MRI, was analysed. Compared with the resting condition, the mean rCBF was markedly increased in the contralateral sensorimotor cortex (M1-S 1) and moderately increased in the contralateral cingulate gyrus and p utamen in both the simple and complex motor tasks. During the complex motor task, in addition to the above, the mean rCBF was markedly incre ased in the supplementary motor area and the contralateral premotor ar ea, and moderately increased in the ipsilateral M1-S1 and cerebellum. In the supplementary motor area, there was a moderate rCBF increase al so during the simple task. However, comparison of the mean rCBF increa se against the resting condition between the two tasks revealed a grea ter increase during the complex task than in the other only in the sup plementary motor area and the ipsilateral M1-S1. Thus, in agreement wi th our previous electrophysiological findings, not only the supplement ary motor area but also the M1-S1 seems to play an important role in t he execution of complex sequential finger movements.