Reaching movements generate reaction forces that affect postural stability, requiring sophisticated coordination between body and arm movement to maintain balance. In voluntary movement, this coordination involves feedforward shifts of posture, and such anticipatory postural muscle activity also accompanies the rapid modulation of an ongoing point to suddenly a shifting target (double-step). However, it is unknown if this early postural activity depends on target-shift predictability and whether arm and body motion are similar coordinated to voluntary movement. Body and arm motion coordination during double-step pointing movements from standing were done under differing conditions of target-shift predictability. In a proportion of trials, the pointing target was displaced, with the predictability of target-shift direction varied between two peripheral targets (target-shift direction known) and two central targets (target-shift direction uncertain). The target jump evoked an adjustment in the arm then body response, opposite to the pointing responses to the initial target. The triggered arm-then-body ordering was consistent across target-shift predictability, although known target-shift direction resulted in closer timing of arm and body onsets. The altered coordination in triggered corrections suggests that the body component in triggered reactions depend on response predictability, showing an altered control of arm and body motion.

中文翻译：

---

受任务可预测性影响的具有触发的指向响应的更改的手臂-身体协调。

到达运动会产生反作用力，这些反作用力会影响姿势的稳定性，因此需要在身体和手臂的运动之间进行复杂的协调以保持平衡。在自发运动中，这种协调涉及姿势的前馈改变，并且这种预期的姿势肌肉活动也伴随着进行中的点的快速调节而突然转变为目标（双步）。但是，尚不清楚这种早期的姿势活动是否取决于目标偏移的可预测性，以及手臂和身体的运动是否类似于自愿运动。从目标站立可预测性的不同条件下，完成了站立站立双步指向动作期间的身体和手臂运动协调。在一定比例的试验中，指示目标被迫转移，目标移动方向的可预测性在两个外围目标（已知目标移动方向）和两个中心目标（目标移动方向不确定）之间变化。目标跳跃引起手臂然后身体响应的调整，这与对初始目标的指向响应相反。尽管已知的目标移动方向导致手臂和身体发作的时间更近，但触发的手臂-身体-身体顺序在目标移动的可预测性方面是一致的。触发校正中协调性的改变表明触发反应中的身体成分取决于反应的可预测性，表明手臂和身体运动的控制已改变。与指向初始目标的指向响应相反。尽管已知的目标移动方向导致手臂和身体发作的时间更近，但触发的手臂-身体-身体顺序在目标移动的可预测性方面是一致的。触发校正中协调性的改变表明触发反应中的身体成分取决于反应的可预测性，表明手臂和身体运动的控制已改变。与指向初始目标的指向响应相反。尽管已知的目标移动方向导致手臂和身体发作的时间更近，但触发的手臂-身体-身体顺序在目标移动的可预测性方面是一致的。触发校正中协调性的改变表明触发反应中的身体成分取决于反应的可预测性，表明手臂和身体运动的控制已改变。