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脑功能最基本的特征。即使是简单的行为，如目标导向的达到，也表现出对感官反馈变化的快速和强大的适应。这些形式的学习已经在行为层面上得到了广泛的表征，并且已经开发了各种模型来提供对这些现象的直观理解。然而，尽管取得了这些进展，但对于潜在的神经回路是如何随着学习而变化的，以及感觉反馈是如何驱动这些变化的，我们知之甚少。该建议解决了这些问题，重点关注手臂视觉反馈移位时发生的快速学习（“视觉移位适应”）。研究表明，当手臂的视觉反馈从真实位置偏移时，例如通过移动棱镜，在视觉定位（物体“看起来”的位置）和本体感觉定位（手臂“感觉”的位置）中观察到代偿性偏移。这些转变使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，本研究将研究视觉和本体感觉如何在大脑中正常整合（“感觉整合”），以及该过程如何随着视觉转移适应（“感觉重新校准”）而变化。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完成，当动物在手臂的视觉反馈移动或不移动的情况下进行感觉引导的到达运动时。大型神经元群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：研究感觉统合的皮层机制。定量测量将对视觉和本体感觉对神经计算的贡献进行测量，神经计算是到达计划的基础。具体地说，视觉反馈的相对权重是从各种视觉反馈变化（包括随机交错试验）对群体活动的影响中推断出来的。这些实验的设计目的是：(1)测试皮层区域是否对感觉输入进行加权，(2)确定哪些皮层区域会随着行为改变其权重，(3)测试该权重是否与统计理论的预测一致。目的二是研究感觉再校准的皮层机制。在长时间暴露于持续的视觉变化（一种驱动感觉重新校准的情况）期间，将对皮层中视觉和本体感觉信号发生的变化进行定量测量。这些实验旨在确定：1)某一特定皮质区域感觉编码的变化是否可以用该区域感觉输入的错位来解释；2)这些变化是否与统计理论的预测相一致。公共卫生相关性：本项目旨在发现大脑皮层中手眼协调神经回路中学习的新机制。这项工作将使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。除了其科学影响，这项工作还有两个潜在的医学应用：1)帮助开发用于运动控制的感觉假肢装置，2)帮助开发针对中风后感觉和感觉运动缺陷的新的原则性治疗方法。

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.