Construction of invariant shape selectivity in the ventral visual stream

描述（由申请人提供）：感知神经科学的一个基本目标是理解我们感知、识别和记忆视觉对象的非凡能力背后的神经元表征。在人类和非人类灵长类动物中，这些表征是通过腹侧视觉流的处理产生的，并通过最高水平的神经元活动模式——猴子下颞叶皮层（IT）来传递。腹侧流解决的关键计算问题是，它产生视觉图像的it神经元表示，传达对象身份和类别的选择性，对对象位置、大小、姿势、照明和杂乱的变化具有容忍度（“不变性”）。事实上，尽管腹侧流的形状选择性特性已经得到了很多研究，但我们对构建这种耐受性的机制知之甚少。这一建议的目标是对腹侧视觉流如何构建宽容（“不变”）视觉形状选择性的机制理解，这是我们物体识别能力的基础。在目标1中，我们问：自然获得的时间连续经验是否“指导”腹侧流中耐受性的形成？我们最近发现，IT神经元形状选择性的容忍度可以通过改变无监督视觉对象经验的时间连续性而强烈而迅速地塑造。为此，我们将使用一系列密切相关的视觉经验操作来系统地测试和表征这种可塑性在位置、大小和姿势容忍学习中的作用。这将阐明其在指导成人视觉对象表征方面的作用，并为长期研究这些强大的表征是如何在早期发育过程中组装起来的奠定基础。在目标2中，我们将采用比较的方法来询问对象信息是如何在两个腹侧流区域（V4与IT）之间转换的。使用相同的猴子、相同的任务和相同的视觉刺激，我们将使用神经元群体方法来问：IT表示的容忍度与V4表示的容忍度是如何变化的？V4的形状选择性是否保留在IT表示中？从V4到IT，视觉表示的稀疏性会改变吗？宽容的形状选择性是如何实时进化的？总之，这些实验将揭示一个核心问题：“IT中的容忍对象选择性是如何从早期的视觉表示中构建的？”，结果将为腹侧视觉流的计算模型提供强有力的约束，并指导我们更普遍地理解皮层信息转换。

DESCRIPTION (provided by applicant): A fundamental goal of perceptual neuroscience is to understand the neuronal representations that underlie our remarkable ability to perceive, recognize, and remember visual objects. In humans and non-human primates, these representations are produced by processing along the ventral visual stream, and conveyed by patterns of neuronal activity in its highest level -- the monkey inferior temporal cortex (IT). The key computational problem the ventral stream solves is that it produces an IT neuronal representation of visual images that conveys selectivity for object identity and category, with tolerance ("invariance") to changes in object position, size, pose, illumination and clutter. Indeed, although the shape selectivity properties of the ventral stream have received much study, we know very little about the mechanisms that construct that tolerance. The goal of this proposal is a mechanistic understanding of how the ventral visual stream constructs the tolerant ("invariant") visual shape selectivity that underlies our object recognition abilities. In Aim 1 we ask: does naturally-acquired temporally contiguous experience "instruct" the formation of tolerance in the ventral stream? We have recently discovered that the tolerance of IT neuronal shape selectivity can be strongly and rapidly sculpted by altered temporal contiguity of unsupervised visual object experience. In this aim, we will use a series of closely-related visual experience manipulations to systematically test and characterize the role of this plasticity in position, size, and pose tolerance learning. This will illuminate its role in instructing adult visual object representation, and set the stage for longer-term studies of how these powerful representations are assembled during early development. In Aim 2 we will take a comparative approach to ask how object information is transformed across two ventral stream areas (V4 vs. IT). Using the same monkeys, same task, and same visual stimuli, we will use neuronal population methods to ask: How is the tolerance of the IT representation changed from the V4 representation? Is V4 shape selectivity preserved in the IT representation? Does the sparseness of visual representation change from V4 to IT? How does tolerant shape selectivity evolve in real time? Together, these experiments will inform a central question: "How is the tolerant object selectivity in IT built from earlier visual representation?", and the results will provide strong constraints on computational models of the ventral visual stream and guide our understanding of cortical information transformation more generally. PUBLIC HEALTH RELEVANCE: Visual object recognition is fundamental to our well-being and our brain is remarkably good at solving this problem even though the same object can appear very differently to our eyes. The overarching goal of these experiments is a mechanistic understanding of how the visual system constructs the patterns of neuronal activity that solve this problem. This will lead to an understanding of the brain processes that allow us to see and evaluate the visual world (e.g. recognize and remember objects).