Nashner L M, Forssberg H
J Neurophysiol. 1986 Jun;55(6):1382-94. doi: 10.1152/jn.1986.55.6.1382.
This study examines the interactions between anteroposterior postural responses and the control of walking in human subjects. In the experimental paradigm, subjects walked upon a treadmill, gripping a rigid handle with one hand. Postural responses at different phases of stepping were elicited by rapid arm pulls or pushes against the handle. During arm movements, EMG's recorded the activity of representative arm, ankle, and thigh segment muscles. Strain gauges in the handle measured the force of the arm movement. A Selspot II system measured kinematics of the stepping movements. The duration of support and swing phases were marked by heel and toe switches in the soles of the subjects' shoes. In the first experiment, subjects were instructed to pull on the handle at their own pace. In these trials all subjects preferred to initiate pulls near heel strikes. Next, when instructed to pull as rapidly as possible in response to tone stimuli, reaction times were similar for all phases of the step cycle. Leg muscle responses associated with arm pulls and pushes, referred to as "postural activations," were directionally specific and preceded arm muscle activity. The temporal order and spatial distribution of postural activations in the muscles of the support leg were similar when arm pull movements occurred while the subject was standing in place and after heel strike while walking. Activations began in the ankle and radiated proximally to the thigh and then the arm. Activations of swing leg muscles were also directionally specific and involved flexion and forward or backward thrust of the limb. When arm movements were initiated during transitions from support by one leg to the other, patterns of postural activations were altered. Alterations usually occurred 10-20 ms before hell strikes and involved changes in the timing and sometimes the spatial structure of postural activations. Postural activation patterns are similar during in-place standing and during the support phase of locomotion. Walking and posture control appear to be separately organized but interrelated activities. Our results also suggest that the stepping generators, not peripheral feedback time locked to heel strikes, modulate postural activation patterns.
本研究考察了人体受试者前后姿势反应与步行控制之间的相互作用。在实验范式中，受试者在跑步机上行走，用一只手握住一个刚性手柄。通过快速拉动或推动手柄来引发不同步阶段的姿势反应。在手臂运动过程中，肌电图记录代表性手臂、脚踝和大腿节段肌肉的活动。手柄中的应变片测量手臂运动的力。一个Selspot II系统测量步行动作的运动学。支撑期和摆动期的持续时间由受试者鞋底的脚跟和脚趾开关标记。在第一个实验中，受试者被指示以自己的节奏拉动手柄。在这些试验中，所有受试者都倾向于在脚跟触地附近开始拉动。接下来，当被指示尽可能快地响应音调刺激进行拉动时，步周期各阶段的反应时间相似。与手臂拉动和推动相关的腿部肌肉反应，称为“姿势激活”，具有方向特异性且先于手臂肌肉活动。当受试者站立不动时以及行走时脚跟触地后进行手臂拉动运动时，支撑腿肌肉中姿势激活的时间顺序和空间分布相似。激活始于脚踝，向近端辐射至大腿，然后是手臂。摆动腿肌肉的激活也具有方向特异性，包括肢体的屈曲和向前或向后的推力。当在从一条腿支撑过渡到另一条腿支撑的过程中启动手臂运动时，姿势激活模式会改变。改变通常发生在脚跟触地前10 - 20毫秒，涉及姿势激活的时间变化，有时还包括空间结构变化。原地站立和运动支撑期的姿势激活模式相似。步行和姿势控制似乎是分别组织但相互关联的活动。我们的结果还表明，步行动作发生器而非与脚跟触地时间锁定的外周反馈调节姿势激活模式。
