Mars Franck, Archambault Philippe S, Feldman Anatol G
Institut de Réadaptation de Montréal, Université de Montréal et Centre de Recherche Interdisciplinaire en Réadaptation, 6300 Darlington, H3S 2J4, Montreal, Quebec, Canada.
Exp Brain Res. 2003 Jun;150(4):515-9. doi: 10.1007/s00221-003-1485-6. Epub 2003 Apr 15.
Recent studies have shown that the hand-pointing movements within arm's reach remain invariant whether the trunk is recruited or not or its motion is unexpectedly prevented. This suggests the presence of compensatory arm-trunk coordination minimizing the deflections of the hand from the intended trajectory. It has been postulated that vestibular signals elicited by the trunk motion and transmitted to the arm motor system play a major role in the compensation. One prediction of this hypothesis is that vestibular stimulation should influence arm posture and movement during reaching. It has been demonstrated that galvanic vestibular stimulation (GVS) can influence the direction of pointing movements when body motion is restrained. In the present study, we analyzed the effects of GVS on trunk-assisted pointing movements. Subjects either moved the hand to a target or maintained a steady-state posture near the target, while moving the trunk forward with the eyes closed. When GVS was applied, the final position of the hand was deviated in the lateral and sagittal direction in both tasks. This was the result of two independent effects: a deviation of the trunk trajectory and a modification of the arm position relative to the trunk. Thus, the vestibular system might be directly involved not only in the control of trunk motion but also in the arm-trunk coordination during trunk-assisted reaching movements.
最近的研究表明，无论躯干是否参与运动，或者其运动被意外阻止，手臂可及范围内的指物动作都保持不变。这表明存在一种补偿性的手臂 - 躯干协调机制，可将手部偏离预期轨迹的程度降至最低。据推测，由躯干运动引发并传递至手臂运动系统的前庭信号在这种补偿中起主要作用。该假设的一个预测是，前庭刺激在伸手过程中应会影响手臂姿势和运动。已经证明，当身体运动受到限制时，前庭电刺激（GVS）会影响指物动作的方向。在本研究中，我们分析了GVS对躯干辅助指物动作的影响。受试者要么将手移向目标，要么在靠近目标的位置保持稳态姿势，同时闭眼向前移动躯干。施加GVS时，在这两项任务中，手部的最终位置在横向和矢状方向上均发生了偏移。这是两种独立效应的结果：躯干轨迹的偏移以及手臂相对于躯干位置的改变。因此，前庭系统可能不仅直接参与躯干运动的控制，还参与躯干辅助伸手动作过程中的手臂 - 躯干协调。
