Visuomotor adaptation in reaching

描述(由申请人提供)：从经验中学习的能力可能是高级大脑功能的最基本特征。即使是简单的行为，如目标导向的达成，也表现出对感觉反馈变化的快速而强大的适应。这些学习形式被广泛地描述为行为层面的特征，并开发了各种模型来提供对这些现象的直观理解。然而，尽管取得了这一进展，人们对潜在的神经回路如何随着学习而变化，或者感觉反馈如何驱动这些变化，知之甚少。这项建议解决了这些问题，侧重于对手臂视觉反馈变化(“视觉变化适应”)做出反应的快速学习。已经证明，当手臂的视觉反馈从真实位置移位时，例如通过移位棱镜，在视觉定位(事物看起来是在哪里)和本体感觉定位(手臂感觉到)中观察到补偿性移动。这些变化使这两种感官重新保持一致。为了揭示这一过程背后的生理机制，这项工作将研究视觉和本体感觉如何正常地整合到大脑中(“感觉整合”)，以及这个过程如何随着视觉变化的适应而改变(“感觉重新校准”)。这将通过记录大脑皮层中几个与手臂运动相关的区域的神经活动来实现，因为动物通过手臂的移动或不移动的视觉反馈进行感官引导的伸展运动。大型神经元群体的活动将同时被记录下来，允许与现有的感觉整合和重新校准的神经模型进行直接比较。目的1是研究感觉整合的皮层机制。定量测量视觉和本体感觉对作为REACH计划基础的神经计算的贡献。具体地说，视觉反馈的相对权重是从随机交叉试验中包含的各种视觉反馈变化对总体活动的影响中推断出来的。这些实验的目的是i)测试皮质区域是否对感觉输入施加权重，ii)确定哪些皮质区域根据行为改变其权重，以及iii)测试这种权重是否与统计理论的预测一致。目的2研究感觉再校准的大脑皮层机制。定量测量将对长期暴露在持续视觉变化中的大脑皮质视觉和本体感觉信号发生的变化进行测量，这种情况会驱动感觉重新校准。这些实验被设计用来确定i)给定皮质区域的感觉编码的变化是否可以用该区域的感觉输入的错位来解释，以及ii)这些变化是否与统计学理论的预测一致。与公共健康相关：该项目旨在发现大脑皮层眼手协调神经回路中的新学习机制。这项工作将让我们更深入地了解我们的运动感觉如何驱动我们大脑的快速变化。除了它的科学影响，这项工作还有两个潜在的医学应用：i)帮助开发用于运动控制的感觉假体设备，以及ii)帮助开发新的原则性疗法，治疗中风后的感觉和感觉-运动障碍。

DESCRIPTION (provided by applicant): The ability to learn from experience is perhaps the most fundamental feature of higher brain function. Even simple behaviors such as goal-directed reaching exhibit rapid and robust adaptation in response to changes in sensory feedback. These forms of learning have been extensively characterized at the behavioral level, and a variety of models have been developed to provide an intuitive understanding of these phenomena. Yet despite this progress, very little is known about how the underlying neural circuits change with learning or how sensory feedback drives these changes. This proposal addresses these questions, focusing on the rapid learning that occurs in response to shifted visual feedback of the arm ("visual-shift adaptation"). It has been shown that when visual feedback of the arm is displaced from the true position, for example with displacing prisms, compensatory shifts are observed in visual localization (where things "look" to be) and proprioceptive localization (where the arm "feels" to be). These shifts bring the two senses back into alignment. In order to uncover the physiological mechanism behind this process, this work will investigate how vision and proprioception are normally integrated in the brain ("sensory integration") and how that process changes with visual-shift adaptation ("sensory recalibration"). This will be accomplished by recording neural activity in several arm-movement related areas in cerebral cortex as animals make sensory guided reaching movements with shifted or unshifted visual feedback of the arm. The activity of large neuronal populations will be simultaneously recorded, permitting direct comparison to existing neural models of sensory integration and recalibration. Aim 1 is to study the cortical mechanism of sensory integration. Quantitative measurements will be made of the visual and proprioceptive contributions to the neural computations that underlie reach planning. Specifically, the relative weighting of visual feedback is inferred from the effect that various visual feedback shifts, included on randomly interleaved trials, have on the population activity. These experiments are designed i) to test whether cortical areas weight sensory inputs, ii) to identify which cortical areas change their weighting with behavior, and iii) to test whether this weighting is consistent with predictions from statistical theory. Aim 2 is to study the cortical mechanism of sensory recalibration. Quantitative measurements will be made of the changes that occur to visual and proprioceptive signals in cortex during extended exposure to a constant visual shift, a situation that drives sensory recalibration. These experiments are designed to determine i) whether the changes in the sensory coding in a given cortical area can be explained by the misalignment of sensory inputs to that area and ii) whether these changes are consistent with predictions from statistical theory. PUBLIC HEALTH RELEVANCE: This project is aimed at discovering new mechanisms of learning in the neural circuits for eye-hand coordination in the cerebral cortex. This work will give us a deeper understanding of how sensory of our movements drives rapid changes in our brains. In addition to its scientific impact, this work has two potential medical applications: i) to aid in the development of sensory prosthetic devices for motor control, and ii) to aid in the development of new, principled therapies for sensory and sensory-motor deficits following stroke.