School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Exp Brain Res. 2010 Mar;201(3):561-73. doi: 10.1007/s00221-009-2073-1.
In this work, we tested the hypothesis that intrinsic kinematic constraints such as Donders' law are adopted by the brain to solve the redundancy in pointing at targets with the wrist. Ten healthy subjects were asked to point at visual targets displayed on a monitor with the three dof of the wrist. Three-dimensional rotation vectors were derived from the orientation of the wrist acquired during the execution of the motor task and numerically fitted to a quadratic surface to test Donders' law. The thickness of the Donders' surfaces, i.e., the deviation from the best fitting surface, ranged between 1 degree and 2 degrees, for angular excursions from +/-15 degrees to +/-30 degrees. The results support the hypothesis under test, in particular: (a) Two-dimensional thick surfaces may represent a constraint for wrist kinematics, and (b) inter-subject differences in motor strategies can be appreciated in terms of curvature of the Donders' surfaces.
在这项工作中，我们检验了这样一个假设，即内在运动学约束（如唐德斯定律）被大脑采用，以解决用手腕指向目标时的冗余问题。我们要求 10 名健康受试者用手腕的三个自由度指向显示器上显示的视觉目标。从执行运动任务期间获得的手腕方向中推导出三维旋转向量，并对其进行数值拟合到二次曲面以检验唐德斯定律。唐德斯曲面的厚度，即偏离最佳拟合曲面的程度，在从 +/-15 度到 +/-30 度的角度范围内变化在 1 度到 2 度之间。这些结果支持了正在测试的假设，特别是：(a) 二维厚曲面可能代表手腕运动学的约束，以及 (b) 可以根据唐德斯曲面的曲率来理解运动策略在个体间的差异。
