視覚標的の突変または消滅による前腕運動の変容とそのモデル(1部 生体を知る)
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概要
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Very fast forearm extensions and flexions toward a visual target within the horizontal plane were investigated. The subjects initiated the movement with maximum effort from a fixed position on hearing a short tone stimulus. In the first experiment, during some movements, target location changed suddenly, thus requiring an intentional correction of the trajectory by the subject. The subject knew the first target location well before the movement was initiated but he did not know when and to where the target position would change. Changes of target location during the reaction or movement time generally elicited movement to the first target, followed by movement to the second one after varying reaction times. The reaction time R_S to the sound command which initiated the movement to the original target was affected by change of target location and decreased by about 25-50 msec when the time from the presentation of the auditory stimulus to change of the target (ISI, interstimulus interval) was -200 msec to -50 msec. And in this range of ISI some of the movements were initiated directly toward the new target. The reaction time R_L to change of target location was a function of ISI: when ISI<150 msec R_L correlated negatively with ISI and when 200 msec <ISI<550 msec, R_L was a little longer than the simple visuomotor reaction time. The movement that initially progressed toward the first target could never begin to deviate toward the second one untill it passed the negative peak of acceleration. In the second experiment, movements were also initiated in response to a tone command but the visually presented target disappeared during some trials at various instants, The subjects were instructed to continue the movement toward the original target location even after target disappearance. The final position reached was a function of target location and time of target disappearance: for a distant target the angle of the final position decreased with time after target disappearance while for a near one it increased with time. This result suggests that the centrally stored target location changes with time if the target disappears. On the basis of the results of the present and previous studies on the fast positioning movements, a model of the forearm movement control system was constructed. It can explain the different modes of the movement control process, the relations among subsystems participating in movement control and movement modification in response to location shift or disappearance of the target.
- バイオメカニズム学会の論文
- 1986-09-25