[Role of the silent period preceding the rapid voluntary movement (author's transl)]

It has been shown that there is the silent period preceding the rapid voluntary movement. The present paper is designed to find the mechanisms of this inhibitory phenomenon and to investigate their role in the voluntary movement. The following results were obtained: 1. It was found that the silent period before the movement was observed not only in reaction trials to visual stimulus but also in voluntary trials without stimulus. 2. The silent period were simultaneously recorded from the rectus femoris, the vastus lateralis and the vastus medialis by upward jumping movement. This finding suggested that this inhibitory phenomenon was a change in excitability of motoneurons innervating the quadriceps. 3. When a subject extended his elbow and knee at the same time, the silent period before the movement could be seen in both triceps brachii and vastus medialis. 4. These results suggest that the upper center sends some inhibitory discharge to the motoneurons before the movement. It is supposed that the silent period preceding the voluntary movement plays a major role in the mechanisms of motor control.