Milner T E
Institut de génie biomédical, Université de Montréal, Québec, Canada.
Neuroscience. 1992 Jul;49(2):487-96. doi: 10.1016/0306-4522(92)90113-g.
A model is proposed in which movement accuracy is regulated by means of corrective actions taken at discrete intervals throughout the course of a movement. A movement, as represented by its tangential velocity profile, cna be decomposed into a series of one or more submovements. Each submovement consists of a prototype velocity profile which can be scaled in magnitude and duration. For planar two-joint movements, we demonstrate that these submovements can be mathematically represented either in terms of velocity profiles or in terms of the underlying joint torque profiles. In either case, the submovements superimpose linearly to produce the composite movement. The model provides a very good fit to tangential velocity profiles recorded from human subjects during three-dimensional arm movements with constraints on accuracy and speed. The model assumes that when a submovement is present, its onset is associated with a change in the direction of the hand path and/or a zero crossing or inflection in at least one of the components of the velocity vector. The model is consistent with a strategy in which precision is achieved by periodic discrete actions which redirect the moving arm in order to bring the hand closer to the target. Since submovements were also observed in slow movements where accuracy constraints had been relaxed, we hypothesize that the strategy of superimposing a series of submovements to make one composite movement may be a general one. We suggest that it would be particularly appropriate for the process of learning a new motor skill.
本文提出了一个模型，其中运动精度是通过在整个运动过程中的离散时间间隔采取的纠正措施来调节的。一个运动，以其切向速度曲线表示，可以分解为一系列一个或多个子运动。每个子运动都由一个原型速度曲线组成，该曲线可以在幅度和持续时间上进行缩放。对于平面双关节运动，我们证明这些子运动可以用速度曲线或潜在的关节扭矩曲线进行数学表示。在任何一种情况下，子运动都是线性叠加以产生复合运动。该模型与在三维手臂运动中对人类受试者记录的切向速度曲线非常吻合，这些运动在精度和速度上受到限制。该模型假设当存在子运动时，其开始与手部路径方向的变化和/或速度矢量的至少一个分量中的过零或拐点相关。该模型与一种策略一致，即通过周期性的离散动作来实现精度，这些动作会重新引导移动的手臂，以使手部更接近目标。由于在精度限制已放宽的缓慢运动中也观察到了子运动，我们假设叠加一系列子运动以形成一个复合运动的策略可能是一种通用策略。我们认为它对于学习新运动技能的过程特别合适。
