A memory of errors in motor adaptation

描述（由申请人提供）：当我们练习一项运动任务时，我们可以在下次重新学习时做得更好。这是如何实现的呢？神经科学的基本假设是，这种被称为“记忆”的现象之所以会发生，是因为当我们重新审视任务时，大脑会回忆起之前学过的运动命令。在这个观点中，运动记忆是对运动命令的记忆。与这些观点相反，这里我们提出运动记忆包括对错误的记忆，也就是说，当我们在一项任务中表现得更好时，通常不是因为我们记住了之前学过的运动命令，而是因为我们记住了之前见过的错误。我们认为，这种反直觉的、以前未知的记忆形式，即错误记忆，可以解释运动学习文献中大量令人困惑和无法解释的实验数据。在这个提议中，我们从一个谜题开始：在一个

DESCRIPTION (provided by applicant): 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 this phenomenon, called 'savings', occurs because when we revisit the task, the brain recalls the motor commands that it had previously learned. In this view, motor memory is a memory of motor commands. In contrast to these views, here we propose that motor memory includes a memory of errors, i.e., when we are better at a task, it is often not because we remember the motor commands that we learned before, but because we remember the errors that we have seen before. We propose that this counter-intuitive and previously unknown form of memory, a memory of errors, can account for a very large body of puzzling and unexplained experimental data in the motor learning literature. In this proposal, we begin with a puzzle: in a motor learning task, humans are able to modulate how much they learn from a given error. In some conditions, they learn a large amount, but in other conditions they learn only a small amount. That is, the brain selects how much it is willing to learn from error. To understand the rules that govern control of error-sensitivity, we manipulate the history of errors that subjects experience, and find that positive autocorrelations of errors up-regulate sensitivity, whereas negative autocorrelations down-regulate sensitivity, but only at the specific errors that were actually experienced. That is, experience of an error produces a change in motor commands via errors-sensitivity, which in turn depends on the history of past errors, allowing the brain to respond differently to an error that was experienced before. We formulate this idea with a set of mathematical equations that extend the current framework of learning and show that this new set of equations, representing memory of errors, seamlessly connects a large body of puzzling data. Building on these preliminary results, we propose two groups of experiments to test the foundations of this new idea. The first set of experiments test the prediction that correlations of past errors will modulate error-sensitivity, and that this modulation will be local to the specific errors that were experience. The second set of experiments test the prediction that modulation of error-sensitivity via memory of errors is the basis for the phenomenon of saving. From a clinical standpoint, understanding error-sensitivity is important as it directly affects motor rehabilitation for neuro-trauma or disease. Our theory provides a recipe to modulate error-sensitivity, which should produce faster adaptation, potentially affecting the duration of rehabilitation. In addition, understanding the relationship between error sensitivity and savings may provide useful clues regarding how to effectively apply rehabilitation techniques to promote faster re-learning outside the clinic.