1981 年 26 巻 1 号 p. 43-56
The study of movement-associated cortical potential was first reported by H.H. Kornhuber and L. Deeke in 1965. The reports as to N_1 potential (readiness potential) of movement-associated cortical potentials beginning 800msec-1500msec in advance of voluntary movement were presented by many investigators, and agreement was reached on some of the points. However, some of the points still remained disagreed. Therefore, the present authors had investigated the relation of N_1 potential with motor control and the difference between N_1 potential and CNV, up to the present, and presented some of the findings. Then, the authors have attempted at elucidating the significance of N_2 potential (motor potential) beginning 91-187msec in advance of voluntary movement, P_2 potential (the first positive potential after movement) beginning about 160msec after voluntary movement, and P_3 potential (the second positive potential after movement) beginning about 263msec after voluntary movement which are constituting the movement-associated cortical potentials, and a few findings have been presented in the previous report. However, data that supported their findings remain inadeqate, up to the present. The present study, therefore, was intented to investigate, in more detail, the relations of N_2 potential, P_2 potential, and P_3 potential to the motor control, with the method of simultaneous measurement of movement-associated cortex potentials, S.S.C.P (somatic, stimulus, cortex, potential) and cortex potential accompanying passive movement. Such method has been applied to the human subjects in very limited ocassions. The following results were obtained: 1) The distribution over the scalp of N_2 potential showed maximum at C_3 in case of voluntary right upper arm flexion movement. The maximum was at C_4 in case of voluntary left upper arm flexion movement 2) The distribution over the scalp of P_2 potential showed maximum at C_z in case of voluntary right upper arm flexion movement. The maximum was also at C_z in case of voluntary left upper arm flexion movement. 3) P_3 potential and positive potential of passive flexion movement appeared both semispheres over central area. However, the difference of the amplitude of the these potentials was not significant. 4) The appearance latency of P_3 potential and of positive potential appearing after passive flexion movement showed quite similar value. When the amplitude of these potentials was compared, P_3 potential showed higher tendency than the positive potential after passive flexion movement. From the results described above, the authors may conclude that (1) N_2 potential reflects expression of nerve excitation, namely, activity of corticalspinal tract concerning efferent discharges of pyramidal tract, (2) P_2 potential dose not reflect peripheral feedback, but suggests the possibility of reflecting central feedback, and (3) P_3 potential reflects peripheral feedback from muscle, joint, and others. These findings are in support of the previous results reported by other investigators.