Department of Psychology and Center for Neural Science, New York University, New York, New York 10003, USA.
J Neurophysiol. 2012 Nov;108(10):2708-16. doi: 10.1152/jn.00355.2012. Epub 2012 Aug 29.
Coordinate systems for movement planning are comprised of an anchor point (e.g., retinocentric coordinates) and a representation (encoding) of the desired movement. One of two representations is often assumed: a final-position code describing desired limb endpoint position and a vector code describing movement direction and extent. The existence of movement-planning systems using both representations is controversial. In our experiments, participants completed reaches grouped by target location (providing practice for a final-position code) and the same reaches grouped by movement vector (providing vector-code practice). Target-grouped reaches resulted in the isotropic (circular) distribution of errors predicted for position-coded reaches. The identical reaches grouped by vector resulted in error ellipses aligned with the reach direction, as predicted for vector-coded reaches. Manipulating only recent movement history to provide better learning for one or the other movement code, we provide definitive evidence that both movement representations are used in the identical task.
运动规划的坐标系由一个锚点（例如，视固着坐标）和一个期望运动的表示（编码）组成。通常假设两种表示形式中的一种：描述期望肢体末端位置的最终位置码和描述运动方向和幅度的向量码。使用这两种表示形式的运动规划系统的存在是有争议的。在我们的实验中，参与者完成了按目标位置分组的到达动作（为最终位置编码提供练习）和按相同的运动向量分组的相同到达动作（为向量编码提供练习）。按目标分组的到达动作导致了与位置编码到达动作预测的各向同性（圆形）误差分布。按向量分组的相同到达动作导致误差椭圆与到达方向一致，这与向量编码到达动作的预测一致。仅通过操纵最近的运动历史来为一个或另一个运动代码提供更好的学习，我们提供了明确的证据，表明在相同的任务中使用了两种运动表示形式。
