Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
Exp Brain Res. 2010 Jul;204(2):163-71. doi: 10.1007/s00221-010-2261-z. Epub 2010 Jun 22.
Despite the infinitely many ways to grasp a spherical object, regularities have been observed in the posture of the arm and the grasp orientation. In the present study, we set out to determine the factors that predict the grasp orientation and the final joint angles of reach-to-grasp movements. Subjects made reach-to-grasp movements toward a sphere to pick it up and place it at an indicated location. We varied the position of the sphere and the starting and placing positions. Multiple regression analysis showed that the sphere's azimuth from the subject was the best predictor of grasp orientation, although there were also smaller but reliable contributions of distance, starting position, and perhaps even placing position. The sphere's initial distance from the subject was the best predictor of the final elbow angle and shoulder elevation. A combination of the sphere's azimuth and distance from the subject was required to predict shoulder angle, trunk-head rotation, and lateral head position. The starting position best predicted the final wrist angle and sagittal head position. We conclude that the final posture of the arm when grasping a sphere to place it elsewhere is determined to a larger extend by the initial position of the object than by effects of starting and placing position.
尽管抓取球体的方式有无数种，但在手臂姿势和抓取方向上已经观察到了一些规律。在本研究中，我们旨在确定预测伸手抓取运动的抓取方向和最终关节角度的因素。实验对象做出伸手抓取球体的动作，将其拿起并放置在指定位置。我们改变了球体的位置以及起始和放置位置。多元回归分析表明，球体相对于实验对象的方位是预测抓取方向的最佳因素，尽管距离、起始位置甚至可能还有放置位置也有较小但可靠的影响。球体与实验对象之间的初始距离是预测最终肘部角度和肩部抬高的最佳因素。预测肩部角度、躯干-头部旋转和头部侧位需要将球体的方位和距离结合起来。起始位置是预测最终腕部角度和矢状头部位置的最佳因素。我们得出的结论是，将球体放置在其他地方时手臂的最终姿势在更大程度上取决于物体的初始位置，而不是起始和放置位置的影响。
