University of Miami, Department of Neurological Surgery, The Miami Project to Cure Paralysis, Miami, FL 33136, United States; University of Wisconsin - Milwaukee, Department of Kinesiology, Milwaukee, WI 53201, United States.
University of Wisconsin - Milwaukee, Department of Kinesiology, Milwaukee, WI 53201, United States.
Neuroscience. 2017 Dec 16;366:184-195. doi: 10.1016/j.neuroscience.2017.10.004. Epub 2017 Oct 12.
Learning a motor task in one condition typically generalizes to another, although it is unclear why it generalizes substantially in certain situations, but only partially in other situations (e.g., across movement directions and motor effectors). Here, we demonstrate that generalization of motor learning across directions and effectors can be enhanced substantially by inducing use-dependent learning, that is, by having subjects experience motor actions associated with a desired trajectory repeatedly during reaching movements. In Experiments 1 and 2, healthy human adults adapted to a visuomotor rotation while concurrently experiencing repetitive passive movements guided by a robot. This manipulation increased the extent of generalization across movement directions (Expt. 1) and across the arms (Expt. 2) by up to 50% and 42%, respectively, indicating crucial contribution of use-dependent learning to motor generalization. In Experiment 3, we applied repetitive transcranial magnetic stimulation (rTMS) to the left primary motor cortex (M1) of the human subjects prior to passive training with the right arm to increase cortical excitability. This intervention resulted in increased motor-evoked potentials (MEPs) and decreased short-interval intracortical inhibition (SICI) in the rTMS group, but not in the sham group. These changes observed in the rTMS group were accompanied by enhanced generalization of visuomotor adaptation across the arms, which was not the case in the sham group. Collectively, these findings confirm the involvement of M1 in use-dependent learning, and suggest that use-dependent learning can contribute not only to motor learning, but also to motor generalization.
在一种条件下学习运动任务通常会泛化到另一种条件，但为什么在某些情况下会大量泛化，而在其他情况下仅部分泛化（例如，跨运动方向和运动效应器）还不清楚。在这里，我们证明通过诱导使用依赖性学习，可以大大增强运动学习在方向和效应器之间的泛化，即让受试者在到达运动期间反复经历与期望轨迹相关的运动动作。在实验 1 和 2 中，健康的成年人类适应了视觉运动旋转，同时在机器人的引导下经历了重复的被动运动。这种操作分别增加了运动方向（实验 1）和手臂之间（实验 2）的泛化程度高达 50%和 42%，表明使用依赖性学习对运动泛化有重要贡献。在实验 3 中，我们在使用右臂进行被动训练之前，对人类受试者的左初级运动皮层（M1）施加重复经颅磁刺激（rTMS），以增加皮质兴奋性。该干预措施导致 rTMS 组的运动诱发电位（MEPs）增加和短程抑制（SICI）减少，但在假刺激组中没有观察到这种情况。rTMS 组中观察到的这些变化伴随着手臂之间的视觉运动适应的增强泛化，而假刺激组则没有这种情况。总之，这些发现证实了 M1 在使用依赖性学习中的参与，并表明使用依赖性学习不仅可以促进运动学习，还可以促进运动泛化。
