Central representation of time during motor learning
Central representation of time during motor learning
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DOI：
10.1073/pnas.96.20.11625
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发表时间：
1999-09-28
影响因子：
11.1
通讯作者：
Mussa-Ivaldi, FA
中科院分区：
文献类型：
--
作者：
Conditt, MA;Mussa-Ivaldi, FA
这项研究源于一项观察，即人类和非人类灵长类动物的大脑都能够形成和记忆手臂动态的非常准确的内部表示。这些动力学建立了施加力和随之而来的手臂运动之间的函数关系，这种关系通常是相当复杂和非线性的。目前的证据表明，电机控制系统能够适应取决于位置、速度和加速度等运动变量的摄动力。我们在这里报道的实验旨在确定运动系统是否也可以适应明确依赖于时间而不是运动变量的力，令人惊讶的是，这些实验得出了否定的答案。当被要求补偿一种可预测的、反复变化的干扰力模式时，受试者学会了通过产生不依赖于时间而是依赖于手臂的速度和位置的力来抵消干扰。根据这一证据，我们得出结论，在负责运动适应的神经结构中，时间和依赖于时间的动力学并没有明确地表示出来。尽管我们的发现不足以排除中枢神经系统内存在计时结构的可能性，但它们与其他研究结果是一致的，这些研究明显未能找到这样一个中枢时钟的证据。
This study stemmed from the observation that the brain of human as well as nonhuman primates is capable of forming and memorizing remarkably accurate internal representations of the dynamics of the arm. These dynamics establish a functional relation between applied force and ensuing arm motion, a relation that generally is quite complex and nonlinear. Current evidence shows that the motor control system is capable of adapting to perturbing forces that depend on motion variables such as position, velocity, and acceleration. The experiments we report here were aimed at establishing whether or not the motor system also may adapt to forces that depend explicitly on time rather than on motion variables, Surprisingly, the experiments suggest a negative answer. When asked to compensate for a predictable and repeated time-varying pattern of disturbing forces, subjects learned to counteract the disturbance by producing forces that did not depend on time but on the velocity and the position of the arm. We conclude from this evidence that time and time-dependent dynamics are not explicitly represented within the neural structures that lire responsible for motor adaptation. Although our findings are not sufficient to rule out the presence of a timing structure within the central nervous system, they are consistent with other investigations that conspicuously failed to find evidence for such a central clock.