受動動作に誘発されるMEGにおよぼす予期の影響

抄録

We previously investigated the effect of movement-associated intention on nervous activities using neurophysiologic indexes in order to estimate how movement is generated under expected or unexpected conditions. In this study, we measured magnetoencephalographic (MEG) signals during passive finger movement, and evaluated the effect of the existence of anticipation on cortical activities. The subjects were 10 right-handed healthy volunteers. The subjects anticipated the passive movement by receiving warning signals before the movement, and the passive movement was generated as the result of the subjects' anticipation. In the first experiment (Experiment I), a series of warning signals was presented to indicate the onset of passive movement. In the second experiment (Experiment II), a warning signal was given to indicate the direction of passive movement. The passive movement was lifting or lowering the right middle finger (only lifting was applied in Experiment I). Consequently, in Experiment I, for passive movement with a warning signal, MEG deflection before the movement and shortening of the peak latency with a reduction in the amplitude of somatosensory evoked field (SEF) components were observed, compared to values under the condition of no warning signal. However, in Experiment II, there was no change in peak latency, but reduction in the SEF amplitude under the conditions of a warning signal being given. The present results indicate a possibility that anticipation prior to the predictable passive movement modulated the cortical activities in physiological condition.