University of Illinois at Chicago, Department of Bioengineering, Chicago, IL 60612, USA.
J Neurophysiol. 2010 Nov;104(5):2512-22. doi: 10.1152/jn.00302.2010. Epub 2010 Aug 25.
Reaching movements to a target usually have stereotypical kinematics. Although this suggests that the desired kinematics of a movement might be planned, does it also mean that deviations from the planned kinematics are corrected by proprioceptive feedback control? To answer this question, we designed a task in which the subjects made center-forward movements to a target while holding the handle of a robot. Subjects were instructed to make movements at a peak velocity of 1 m/s. No further instructions were given with respect to the movement trajectory or the velocity time profile. In randomly chosen trials the robot imposed servo-controlled deviations from the previously computed unperturbed velocity and position time profiles. The duration of the velocity deviations and the magnitude of accumulated position deviations were manipulated. The subjects were instructed to either "Attempt to correct" or "Do not correct" the movement. The responses to the imposed deviations in the surface electromyograms in the elbow and shoulder agonist muscles consisted of an initial burst followed by a sharp decrease in the "Do not correct" condition or by sustained activity in the "Attempt to correct" condition. The timing and magnitude of the initial response burst reflected those of the velocity deviations and were not affected by the instruction. The timing and magnitude of the late response activity reflected position feedback control and were strongly affected by the instruction. We suggest that proprioceptive feedback control is suppressed in the beginning of the movement, then velocity feedback control is activated in the middle of the movement to control a desired velocity, whereas position feedback control is facilitated late in the movement to acquire the final position.
到达目标的运动通常具有典型的运动学特征。尽管这表明运动的期望运动学可能是预先计划好的，但这是否也意味着运动的运动学偏差可以通过本体感受反馈控制来纠正？为了回答这个问题，我们设计了一项任务，要求受试者在握住机器人手柄的同时向目标做中心向前的运动。要求受试者以 1m/s 的峰值速度进行运动。对于运动轨迹或速度时间曲线，没有给出进一步的指示。在随机选择的试验中，机器人施加了受控的速度和位置时间曲线偏差。偏差的持续时间和累积位置偏差的幅度被操纵。要求受试者“尝试纠正”或“不纠正”运动。在肘部和肩部主动肌的表面肌电图中，对施加的偏差的反应包括初始爆发，然后在“不纠正”条件下急剧下降，或在“尝试纠正”条件下持续活动。初始响应爆发的时间和幅度反映了速度偏差的时间和幅度，不受指令的影响。后期响应活动的时间和幅度反映了位置反馈控制，并且受到指令的强烈影响。我们认为，本体感受反馈控制在运动开始时被抑制，然后在运动中期激活速度反馈控制以控制期望的速度，而位置反馈控制在运动后期被促进以获得最终位置。
