Adaptation to visual motion

描述(申请人提供)：大脑受到经验的强烈影响，无论是在发育阶段还是在成年阶段。准确地了解经验如何改变大脑及其处理过程是神经科学的一个中心问题，从学习和记忆的研究到损伤后皮质重组的研究。在感觉处理领域，我们知道知觉和大脑皮层神经元都受到适应的强烈影响--前几十毫秒到许多分钟的感觉输入。由于其快速的时间尺度，这种形式的可塑性很可能是正在进行的感觉处理的关键组成部分。我们的长期目标是了解适应的影响以及它们对视力的贡献。以前的工作已经证实，适应改变了整个视觉系统的神经元反应特性，有时在不同的处理阶段以不同的方式改变。这个项目的目标是，在视觉运动处理路径的早期阶段，确定神经元如何适应视觉输入的任意空间和时间模式。在第一系列实验中，我们将确定初级视皮层和纹外区神经元的反应和调谐如何受到不同空间形式、大小和持续时间的个体视觉刺激的影响。在这些实验中，我们将利用电极阵列，允许我们同时对许多神经元进行采样，并研究它们之间的相互作用。根据初步的和已发表的工作，我们假设由个体刺激触发的可塑性用于维持局部皮质网络中的活动平衡，而不是像先前所建议的那样优化个体细胞的感觉编码。因此，我们提出，并不是所有有效驱动视觉神经元的刺激都会诱导可塑性。在我们的第二系列实验中，我们将评估皮质神经元如何适应以动态、连续序列呈现的输入集合的统计数据。我们在这些实验中的假设是，神经元根据这样的集合中的输入范围进行调整，这种可塑性是一种快速的增益控制，不同于持续刺激引发的影响。我们在这项研究中获得的知识对于理解可塑性的轨迹和性质如何取决于感觉输入的性质将是重要的。这反过来又是重要的，使我们能够整合在心理物理、神经成像和神经生理学研究中获得的信息，这些研究将适应作为研究视觉系统的工具。此外，我们解决的许多问题对于其他形式的可塑性的研究也是共同的，例如损伤后的皮质重组。通过研究大脑皮层回路是如何受到近期刺激史的影响，我们希望更全面地了解这些回路的学习和重组能力。公共卫生相关性本项目旨在确定视觉系统如何适应最近的感官输入。研究感觉经验引起的快速可塑性可能会为许多临床问题提供重要的知识，包括了解中枢(例如中风)或外周(例如四肢截肢)损伤后大脑如何重组，以及设计感官设备(例如人工耳蜗或视觉辅助设备)以提取或插入信号到大脑中。

DESCRIPTION (provided by applicant): The brain is affected strongly by experience, both during development and in adulthood. Understanding precisely how experience alters the brain and its processing is a central question in neuroscience, from studies of learning and memory to those of cortical reorganization following injury. In the realm of sensory processing, we know that both perception and cortical neurons are strongly affected by adaptation--the sensory input of the preceding tens of milliseconds to many minutes. Because of its rapid time scale, this form of plasticity is likely to be a critical component of ongoing sensory processing. Our long-term goal is to understand the effects of adaptation and how they contribute to vision. Previous work has established that adaptation alters neuronal response properties throughout the visual system, sometimes in different ways at different stages of processing. The goal of this project is to determine, for the early stages of the visual motion processing pathway, how neurons adapt to arbitrary spatial and temporal patterns of visual input. In the first series of experiments, we will determine how the responsiveness and tuning of neurons in primary visual cortex and in extrastriate area MT are affected by individual visual stimuli of different spatial form, size and duration. In these experiments, we will make use of electrode arrays that allow us to sample many neurons simultaneously and to study interactions among them. Based on preliminary and published work, we hypothesize that the plasticity triggered by individual stimuli serves to maintain the balance of activity in a local cortical network, not to optimize the sensory encoding of individual cells as previously suggested. As a result, we propose that not all stimuli that are effective at driving visual neurons will induce plasticity. In our second series of experiments, we will evaluate how cortical neurons adjust to the statistics of an ensemble of inputs, presented in a dynamic, continuous sequence. Our hypothesis in these experiments is that neurons adjust to the range of inputs in such ensembles and that this plasticity is a rapid gain control that is distinct from the effects triggered by persistent stimuli. The knowledge we gain in this study will be important for understanding how the locus and nature of plasticity depends on the properties of sensory input. This, in turn, is important for allowing us to integrate information gained in psychophysical, neuroimaging, and neurophysiological studies that use adaptation as a tool to study the visual system. In addition, many of the questions that we address are common to studies of other forms of plasticity, such as cortical reorganization after injury. By studying how cortical circuits are affected by recent stimulus history, we hope to learn more generally about the capacity of these circuits to learn and reorganize. PUBLIC HEALTH RELEVANCE This project aims to determine how the visual system adapts to recent sensory input. Studying the rapid plasticity caused by sensory experience is likely to provide knowledge important for a number of clinical issues, including understanding how the brain reorganizes after central (e.g. stroke) or peripheral (e.g. limb amputation) injury and designing sensory devices (e.g. artificial cochlea or visual aids) that extract or insert signals into the brain.