Neural mechanisms of shape perception

描述（由申请人提供）：视力是我们幸福的重要组成部分。然而，允许视觉对象在其位置变化下稳定感知的神经机制尚未得到充分理解。特别是，我们目前缺乏关于神经反应如何在腹侧视觉通路中转换的具体知识，在腹侧视觉通路中进行视觉物体识别。在这里，我们提出用自然刺激探测腹侧通路内的视觉区V2和V4神经元，以系统地确定它们的刺激选择偏好。自然刺激为研究神经特征选择性提供了一种系统的方法，因为它们在视觉处理的各个阶段都会引起神经元的强烈反应，而且它们构成的刺激集与普遍的神经特征选择性的特定假设无关。我们最近开发了统计方法，允许表征用自然刺激探测的神经元的特征选择性，并考虑到神经反应的非线性方面。扩展这些方法来解释外皮层视觉区神经元的反应可以耐受刺激位置的变化这一事实（目的1），将允许系统地表征这些神经元在自然条件下的刺激偏好。每个神经元的反应将根据与神经反应最相关的两个局部刺激特征来表征。这将提供对视觉场景中被认为发生在V4响应中的弯曲元素的选择性的直接度量（目标2）。最后，我们将测试神经特征选择性的特定参数，如方向和曲率，是否决定了对物体位置移动的容忍度增加的方向（目标3）。了解健康神经系统中形状感知的神经机制是开发有效治疗神经系统疾病的关键因素，如统觉性失认症，其中视觉物体识别受损。公共卫生相关性：本研究将阐明形状感知的神经机制。在一些影响视力的神经系统疾病中，这些神经过程被破坏。了解健康神经系统中形状感知的神经机制是开发有效治疗视觉物体识别受损的神经系统疾病的关键因素。

Description (provided by applicant): Vision is an essential part of our well-being. Yet, the neural mechanisms allowing for the stable perception of visual objects under variations in their position are not sufficiently understood. In particular, we currently lack specific knowledge of how neural responses are transformed in the ventral visual pathway where visual object recognition is performed. Here we propose to probe neurons in visual areas V2 and V4 within the ventral pathway with natural stimuli in order to systematically determine their stimulus selectivity preferences. Natural stimuli offer a systematic way to study neural feature selectivity because they elicit robust responses from neurons at all stages of visual processing and because they constitute a stimulus set that is not tied to a particular hypothesis about prevalent neural feature selectivity. We have recently developed statistical methods that allow the characterization of the feature selectivity of neurons that are probed with natural stimuli, and which take into account nonlinear aspects of neural responses. Extending these methods to account for the fact that the responses of neurons in extrastriate visual areas can be tolerant to shifts in stimulus position (aim 1) will allow the systematic characterization of the stimulus preferences of these neurons under natural conditions. Responses of each neuron will be characterized according to the two localized stimulus features that are most relevant for the neural responses. This will provide a direct measure of the selectivity to curved elements in visual scenes thought to occur in V4 responses (aim 2). Finally, we will test whether specific parameters of neural feature selectivity, such as orientation and curvature, determines the directions of increased tolerance to shifts in object position (aim 3). Understanding the neural mechanisms of shape perception in the healthy nervous system is a key element in developing effective therapies for neurological disorders, such as apperceptive agnosia, where visual object recognition is impaired. PUBLIC HEALTH RELEVANCE: This study will elucidate the neural mechanisms responsible for shape perception. These neural processes are disrupted in several neurological disorders affecting vision. Understanding the neural mechanisms of shape perception in the healthy nervous system is a key element of developing effective therapies for neurological disorders where visual object recognition is impaired.