The multiple components of motor memory

当我们练习一项运动任务时，我们可以在下一次重温它时做得更好。这是如何实现的？这个 神经科学中的基本假设是，在实践中，我们了解到刺激之间的联系 以及适当的马达指令。然而，这一观点很难与两个基本观点相一致 行为结果：(1)当学习之后是长时间的冲刷(去除干扰)时， 运动记忆似乎受到保护，不会被擦除(称为“保存”)。为什么学习之后会有 冲刷不会消除刺激和运动指令之间的关联？(2)当冲刷 其次是学习相反的扰动，被试表现出元学习，即表现更好 而不是在一种与他们最初了解到的相反的扰动中天真。如何学习才能 将刺激与运动指令的一个方向联系起来，然后消除对相反方向学习的帮助 方向？在这里，我们从一个新的角度来处理这些问题：支持 小脑中的运动学习。我们认为，在小脑中，浦肯野细胞(P细胞)的微簇 是根据他们对错误的偏好进行组织的。这种偏好表现在他们的复合尖峰调谐上 (错误编码)，这反过来又提供了一个坐标系，可以在其中理解简单的尖峰。这个 P细胞的错误偏好使其在错误改变时，解剖上不同的P细胞微簇是 被招募了。因此，当扰动之后是冲刷时，错误会改变方向，并与新的 一组P细胞，在不抹去旧记忆的情况下产生新记忆。同样的假设解剖表明 元学习的出现并不是因为运动指令的相似性，而是因为 错误。利用这一假设，我们表明，当P细胞的简单尖峰被组织成微簇时， 运动的精致编码出现了。我们建议测试一系列关于以下两个方面的预测 小脑错误依赖学习的神经生理学关联及其行为关联 健康人的储蓄和元学习。最后，我们利用这一理论更好地理解了 小脑受损患者的运动学习。 从临床角度来看，我们的工作旨在了解大脑如何存储运动记忆，以及 它如何上调从错误中学习，以及与神经后运动康复相关的问题- 创伤和疾病。我们的理论提供了一个调整误差敏感度的配方，这应该会产生更快的 运动学习，可能影响康复的持续时间。

When we practice a motor task, we can do it better the next time we revisit it. How is this accomplished? The basic assumption in neuroscience has been that during practice, we learn an association between the stimulus and the appropriate motor commands. However, it has been difficult to reconcile this view with two basic behavioral results: (1) when learning is followed by a long period of washout (removal of the perturbation), the motor memory appears protected from erasure (termed “savings”). How is it that learning followed by washout does not erase the association between stimulus and motor commands? (2) When washout is following by learning of the opposite perturbation, subjects exhibit meta-learning, i.e., performance is better than naïve in a perturbation opposite to the one that they had initially learned. How could learning to associate a stimulus to one direction of motor commands followed by washout help in learning in the opposite direction? Here, we approach these problems from a new perspective: the neural architecture that supports motor learning in the cerebellum. We propose that in the cerebellum, micro-clusters of Purkinje cells (P-cells) are organized based on their preference for error. This preference is expressed in their complex-spike tuning (encoding of error), which in turn provides a coordinate system in which simple spikes can be understood. The P-cell’s error preference makes it so that when error changes, anatomically distinct P-cell micro-clusters are recruited. As a result, when a perturbation is followed by washout, error changes direction and engages new groups of P-cells, producing a new memory without erasing the old. The same hypothesized anatomy suggests that meta-learning arises not because of similarity of the motor commands, but because of the similarity of errors. Using this hypothesis we show that when simple spikes of P-cells are organized into micro-clusters, an exquisite encoding of motion emerges. We propose to test a host of predictions regarding both the neurophysiological correlates of error-dependent learning in the cerebellum, and its behavioral correlates of savings and meta-learning in healthy people. Finally, we use the theory to better understand a latent form of motor learning in people with damage to their cerebellum. From a clinical perspective, our work aims to understand how the brain stores motor memories, and how it up-regulates learning from error, questions that are relevant to motor rehabilitation following neuro- trauma and disease. Our theory provides a recipe to modulate error-sensitivity, which should produce faster motor learning, potentially affecting the duration of rehabilitation.