Computational and Biological Learning Laboratory, Department of Engineering, University of Cambridge, Trumpington St., Cambridge CB2 1PZ UK.
J Neurophysiol. 2011 Apr;105(4):1722-31. doi: 10.1152/jn.00780.2010. Epub 2011 Jan 27.
Rhythmic and discrete arm movements occur ubiquitously in everyday life, and there is a debate as to whether these two classes of movements arise from the same or different underlying neural mechanisms. Here we examine interference in a motor-learning paradigm to test whether rhythmic and discrete movements employ at least partially separate neural representations. Subjects were required to make circular movements of their right hand while they were exposed to a velocity-dependent force field that perturbed the circularity of the movement path. The direction of the force-field perturbation reversed at the end of each block of 20 revolutions. When subjects made only rhythmic or only discrete circular movements, interference was observed when switching between the two opposing force fields. However, when subjects alternated between blocks of rhythmic and discrete movements, such that each was uniquely associated with one of the perturbation directions, interference was significantly reduced. Only in this case did subjects learn to corepresent the two opposing perturbations, suggesting that different neural resources were employed for the two movement types. Our results provide further evidence that rhythmic and discrete movements employ at least partially separate control mechanisms in the motor system.
日常生活中，手臂会有节奏且不连续地运动，人们对于这两种运动是否由相同或不同的神经机制引起存在争议。本研究通过运动学习范式中的干扰来检验节奏和离散运动是否至少部分地使用了不同的神经表示。实验要求被试者在右手进行圆形运动的同时，暴露在依赖于速度的力场中，该力场会使运动路径的圆度发生偏差。在每 20 圈的一轮结束时，力场的偏差方向会反转。当被试者仅进行节奏性或离散性的圆形运动时，在切换到两种相反的力场时会观察到干扰。然而，当被试者在节奏性和离散性运动之间交替进行时，即每一种运动都与一个力场的偏差方向相关联，干扰显著减少。只有在这种情况下，被试者才能学习到两种相反的力场之间的核心表现，这表明不同的神经资源被用于两种运动类型。我们的研究结果进一步证明了在运动系统中，节奏和离散运动至少部分地使用了不同的控制机制。
