Schmidt R A, Sherwood D E, Walter C B
Department of Kinesiology, University of California, Los Angeles 90024.
Exp Brain Res. 1988;69(2):344-54. doi: 10.1007/BF00247579.
Modifications to the underlying motor control of rapid reversal movements (flexion-extension of the elbow) to accommodate experimentally induced changes in the movement time (MT) with constant movement amplitude were examined in man. MT was altered between conditions via instructions and feedback, resulting in seven distinct MT levels (from 100 to 250 ms to the reversal point) with essentially constant movement amplitude. As MT was decreased, the large increases in acceleration were met by two changes in motor control: (a) two- to three-fold increases in the peak accelerations and peak amplitudes of the agonist and antagonist EMGs, and (b) a systematic "compression" of the temporal structure of the entire acceleration-time and EMG-time patterns. This temporal "compression" with increased velocity caused by shifts in MT (distance constant) are considerably different from the constant-duration EMG bursts found when velocity is altered by changing movement distance (where MT is nearly constant). Our findings indicate that MT is a determiner of the temporal structure of rapid actions, and suggest that MT should be regarded as an important controlled variable, and not simply as an emergent property of variations in velocity.
研究了人类在实验诱导的运动时间（MT）变化且运动幅度恒定的情况下，对快速反向运动（肘部屈伸）的基础运动控制进行的调整。通过指令和反馈在不同条件下改变MT，产生了七个不同的MT水平（到反向点的时间从100到250毫秒），运动幅度基本恒定。随着MT的减小，加速度的大幅增加通过运动控制的两个变化来应对：（a）主动肌和拮抗肌肌电图的峰值加速度和峰值幅度增加两到三倍，以及（b）整个加速度-时间和肌电图-时间模式的时间结构出现系统性“压缩”。由MT变化（距离恒定）导致的速度增加引起的这种时间“压缩”，与通过改变运动距离（MT几乎恒定）来改变速度时发现的持续时间恒定的肌电图爆发有很大不同。我们的研究结果表明，MT是快速动作时间结构的决定因素，并表明MT应被视为一个重要的受控变量，而不仅仅是速度变化的一种涌现特性。
