Wang Wanyue, Dounskaia Natalia
Kinesiology Program, Arizona State University, 500 N. 3rd Street, Phoenix, AZ, 85004, USA.
Exp Brain Res. 2015 Jul;233(7):2141-53. doi: 10.1007/s00221-015-4285-x. Epub 2015 Apr 26.
We previously demonstrated a tendency to perform arm movements by using a trailing joint control pattern during which either the shoulder or elbow is rotated actively and the other (trailing) joint is rotated predominantly passively, by interaction torque during horizontal movements and by interaction and gravitational torque during 3D arm movements. This tendency was established with a free-stroke drawing task that required production of series of strokes in randomly selected directions from the center to the perimeter of a horizontal circle. The studies demonstrated that within a planar workspace, the usage of the trailing pattern depends on movement direction and the most frequently selected directions are those providing the opportunity to use the trailing pattern. Here, we studied whether the opportunity to use the preferred trailing pattern also depends on the orientation of the planar workspace. The free-stroke drawing task was performed with unconstrained arm movements within circles of a left-diagonal (LD) and right-diagonal (RD) orientation. Two pronounced preferred directions were revealed in the LD condition, and they were the directions in which the trailing pattern was used. Directional preferences were less pronounced, and the trailing pattern was not observed in any directions in the RD condition. Also, subjects identified the RD condition as inconvenient. The results reinforce the previous finding of the propensity to use the trailing pattern during arm movements. They also suggest that orientations of the workspaces in manual activities should be designed to support the trailing pattern as a favored type of joint control.
我们之前证明了在手臂运动过程中存在一种采用尾随关节控制模式进行手臂动作的倾向。在这种模式下，水平运动时通过相互作用扭矩，三维手臂运动时通过相互作用和重力扭矩，使得肩部或肘部主动旋转，而另一个（尾随）关节主要是被动旋转。这种倾向是通过一项自由笔画绘制任务确定的，该任务要求从水平圆的中心到周边在随机选择的方向上绘制一系列笔画。研究表明，在平面工作空间内，尾随模式的使用取决于运动方向，最常选择的方向是那些提供使用尾随模式机会的方向。在此，我们研究了使用首选尾随模式的机会是否也取决于平面工作空间的方向。在左对角线（LD）和右对角线（RD）方向的圆内进行无约束手臂运动的自由笔画绘制任务。在LD条件下揭示了两个明显的首选方向，它们就是使用尾随模式的方向。在RD条件下，方向偏好不太明显，并且在任何方向都未观察到尾随模式。此外，受试者认为RD条件不方便。这些结果强化了之前关于手臂运动过程中使用尾随模式倾向的发现。它们还表明，手动活动中工作空间的方向应设计成支持尾随模式作为一种受青睐的关节控制类型。
