A model system to study the interaction of multiple processes for motor learning

描述(由申请人提供)：人类拥有非常快地学习运动任务的非凡能力。最近的发现开始发现，这种能力得到了多个学习系统的支持，每个学习系统都有自己独特的计算功能。这项研究计划的目标是在计算和神经系统水平上描述这些学习过程。至少已经确定了三个不同学习机制的签名。强化学习可以将任务成功与特定行动联系起来，以更好地指导 在相互竞争的动作选择中进行选择。前向模型可以学习对选定动作的感觉后果进行预测，以提高运动执行力。虽然这两个过程能够改善表现，一个基于加强，另一个基于移动错误，但它们需要一个相对缓慢、渐进的过程，需要广泛的练习。人类能力的一个显著特征是能够采用明确的策略，以更快的时间尺度促进学习。我们假设，这三个过程依赖于不同的神经回路，这些神经回路可以在运动学习任务中同时运行。每一个都可以在很大程度上独立运作，但在某些情况下，它们可以相互作用，以汇聚共同的学习解决方案。我们将利用一个简单的学习任务，包括视觉运动旋转，以参数方式操纵这些过程对运动学习的相对贡献。我们认为，任务概念化和反馈的变化在决定这些过程的相对参与度方面至关重要。实证测试和计算模型将提供对这些假设的严格分析，并开发基于过程的运动学习描述。这些过程的神经解剖学基础将通过测试患有小脑或基底节退行性疾病的神经学人群以及影响前额叶区域的皮质损伤患者来探索。我们认为强化学习、前向模型适应和基于策略的控制可能在几乎所有的运动学习任务中起作用，但它们对学习的个体贡献在很大程度上被忽视了。如果学习是这些过程的加权贡献，那么任务信息的差异以及利用这些信息的个体差异将影响对学习的相对贡献，即使基本任务保持不变。归根结底，了解多个系统如何有助于学习，应该导致制定最优培训方案，要么设计成针对受损系统，要么偏向于依赖相对完整的系统。

DESCRIPTION (provided by applicant): Humans possess a remarkable ability to learn motor tasks very quickly. Recent findings are beginning to discover that this ability is supported by multiple learning systems, each with their unique computational features. The goal of this research proposal is to characterize these learning processes at a computational and neural systems level. The signatures of at least three separate learning mechanisms have been identified. Reinforcement learning can relate task success with a particular action to better guide selection among competing action alternatives. A forward model can learn to make predictions about the sensory consequences of a selected action to improve motor execution. While these two processes are capable of refining performance, one based on reinforcement and the other from movement error, they entail a relatively slow, gradual process requiring extensive practice. A striking feature of human competence is the ability to employ explicit strategies that can facilitate learning at a much faster time scale. We hypothesize that these three processes are dependent on distinct neural circuits that can operate concurrently during a motor learning task. Each may operate with a significant degree of independence, yet they can, in certain circumstances, interact to converge of a common learning solution. We will exploit a simple learning task involving a visuomotor rotation to parametrically manipulate the relative contribution of these processes to motor learning. We propose that changes in task conceptualization and feedback are critical in determining the relative engagement of these processes. Empirical tests and computational modeling will provide a rigorous analysis of these hypotheses and to develop a process-based account of motor learning. The neuroanatomical substrates of these processes will be explored by testing neurological populations with degenerative disorders of the cerebellum or basal ganglia, and patients with cortical lesions affecting prefrontal regions. We assume that reinforcement learning, forward model adaptation, and strategy-based control are likely operative in nearly all motor learning tasks, but their individual contribution to learning has largely been overlooked. If learning is the weighted contribution of these processes, then differences in task information as well as individual differences in the exploitation of this information will influence the relative contribution to learning, even when the basic task remains unchanged. Ultimately, understanding how multiple systems contribute to learning should lead to the development of optimal training protocols either designed to target impaired systems or bias performance to rely on systems that are relatively intact.