Neural processing in the ventral visual pathway during object search

描述（由申请人提供）：本提案的目标是准确描述当我们寻找特定的视觉物体时，大脑中视觉区域所起的多种作用。定位一个特定的物体需要我们1)激活我们所寻找的目标的记忆神经表征，2)对我们在搜索中遇到的每个物品形成神经表征，3)比较这两种表征，以确定当前看到的物体是否与我们所寻找的物体相匹配。我们知道，记忆一个物体的过程激活了大脑中经典定义的“视觉”区域的神经元，这表明这些视觉区域在寻找物体时可能扮演着比静态处理视觉场景更重要的角色。这一观点得到了其他证据的支持，包括我们自己的初步数据。在具体目标1中，我们建议通过测量当前看到的刺激的视觉表征在多大程度上取决于在不同视觉处理水平（即V4和IT区域）寻找目标的身份来表征这一作用。在找到这样的依赖关系后，我们将设法确定它们完成了什么。例如，视觉系统可能会调整其检测器以增加目标的可分辨性。同样，这些视觉神经元的反应可能代表目标和当前所看到的场景之间比较的结果。在具体目标2中，我们的动机是，现实世界的对象搜索涉及到在位置、大小、背景和姿势的变化中找到一个对象，我们建议描述视觉系统在搜索这些保持身份的对象转换子集中的目标中的作用。最后，在具体目标3中，我们建议表征视觉神经元在记忆中保留视觉刺激但物理上没有视觉刺激时的活动（“持续活动”），以更好地理解视觉系统中记忆和寻找目标的神经特征。

DESCRIPTION (provided by applicant): The goal of this proposal is to arrive at an accurate description of the multiple roles that visual areas in the brain play when we are looking for a specific visual object. Locating a specific object requires that we 1) activate a remembered, neural representation of our sought target, 2) develop a neural representation of each item we encounter as we search, and 3) compare these two representations to determine whether the object currently in view matches the object that we seek. We know that the process of remembering an object activates neurons in classically defined 'visual' areas of the brain, suggesting that these visual areas may play a role beyond statically processing the visual scene when searching for an object. This notion is supported by other lines of evidence, including our own preliminary data. In Specific Aim 1, we propose to characterize this role by measuring the degree to which the visual representation of a currently viewed stimulus also depends on the identity of a sought target at different levels of visual processing (i.e. areas V4 and IT). Upon finding such dependencies, we will seek to determine what they accomplish. For example, the visual system might adjust its detectors to increase the discriminability of a target. Similarly, the responses of these visual neurons may represent the outcome of a comparison between the target and the scene currently held in view. In Specific Aim 2, we are motivated by the notion that real-world object search involves finding an object across changes in position, size, background and pose, and we propose to characterize the role of the visual system in searching for a target across a subset of these identity- preserving object transformations. Finally, in Specific Aim 3, we propose to characterize the activity of visual neurons when a visual stimulus is held in memory but no visual stimulus is physically present ("persistent activity") to better understand the neural signature of the remembered and sought target in the visual system. PUBLIC HEALTH RELEVANCE: To understand how visual information is processed in the brain, it is fundamental to understand how the external world is represented by neural signals in visual cortex and how memories and goals influence and interact with that representation. This proposal seeks to understand the fundamental principles by which the visual system transforms the neural representation of images when looking for a specific visual object. Understanding the neural coding of objects is critical to a deep understanding of human visual perception and memory, and is needed to meaningfully repair the disruption of these brain processes or to create prosthetics that may stand in for such disruption.