Sabes P N, Jordan M I
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Neurosci. 1997 Sep 15;17(18):7119-28. doi: 10.1523/JNEUROSCI.17-18-07119.1997.
A novel obstacle avoidance paradigm was used to investigate the planning of human reaching movements. We explored whether the CNS plans arm movements based entirely on the visual space kinematics of the movements, or whether the planning process incorporates specific details of the biomechanical plant to optimize the trajectory plan. Participants reached around an obstacle, the tip of which remained fixed in space throughout the experiment. When the obstacle and the start and target locations were rotated about the tip of the obstacle, the visually specified task constraints retained a rotational symmetry. If movements are planned in visual space, as indicated from a variety of studies on planar point-to-point movements, the resulting trajectories should also be rotationally symmetric across trials. However, systematic variations in movement path were observed as the orientation of the obstacle was changed. These path asymmetries can be accounted for by a class of models in which the planner reduces the likelihood of collision with the obstacle by taking into account the anisotropic sensitivity of the arm to external perturbations or uncertainty in joint level control or proprioception. The model that best matches the experimental results uses planning criteria based on the inertial properties of the arm.
一种新颖的避障范式被用于研究人类伸手动作的规划。我们探究了中枢神经系统（CNS）是否完全基于动作的视觉空间运动学来规划手臂动作，或者规划过程是否纳入了生物力学系统的特定细节以优化轨迹规划。参与者绕过一个障碍物伸手，在整个实验过程中障碍物的尖端在空间中保持固定。当障碍物以及起始和目标位置围绕障碍物尖端旋转时，视觉指定的任务约束保持旋转对称性。如果动作是在视觉空间中规划的，正如从各种关于平面点对点动作的研究中所表明的那样，那么在不同试验中得到的轨迹也应该是旋转对称的。然而，随着障碍物方向的改变，观察到了动作路径的系统性变化。这些路径不对称性可以由一类模型来解释，在这类模型中，规划者通过考虑手臂对外部扰动的各向异性敏感性或关节水平控制或本体感觉中的不确定性来降低与障碍物碰撞的可能性。与实验结果最匹配的模型使用基于手臂惯性特性的规划标准。
