Neural Mechanisms of Feature Integration

描述(申请人提供)：推动现代视觉思维的一个中心观察是，视觉系统将刺激分解成它们的组成特征，由具有不同特征选择性的神经元代表。这些特征选择神经元携带的信号如何整合成连贯的物体表征是未知的，也是神经生物学中尚未解决的中心问题之一。通过在心理、物理和神经元层面上仔细分析知觉整合的时间特性，可以洞察解决这一问题的机制。我们将采用这一策略，重点关注一个简单而明确的特征集成案例：视觉中最基本和研究最充分的两个特征的结合：颜色和方向。当前提案的中心目标是了解视觉系统如何连接这些特征。这一目标将在以下具体目标中实现。目的1.比较视觉系统对这两个特征的颜色、方向和连接的时间分辨率，在人类的知觉水平和粗体水平上，在猴子的神经元水平上。目的2.描述颜色和方向调节的时间动态，以及它们对亮度对比度的依赖，并量化在自然视觉刺激下这些特性的任何变化。目的3.检验空间注意是否在颜色和方位的整合中起作用。相关性：我们目前缺乏对特征整合机制的了解，这表明我们对物体感知受损的障碍的病理理解存在显著差距，如同时性失认、面容失认、整合性视觉失认、巴林特综合征和与忽视相关的以物体为中心的损害。填补这一空白将提供有助于解释和治疗这些疾病和相关疾病的理解。拟议的实验将通过(1)表征调节特征整合的神经机制的时间分辨率，(2)开发和测试调节简单且明确定义的特征整合形式的神经计算的数学严格模型，以及(3)确定注意是否在特征连词的形成中起作用，从而缩小这一差距。

DESCRIPTION (provided by applicant): A central observation that has driven modern thinking about vision is that the visual system decomposes stimuli into their constituent features, represented by neurons with different feature selectivities. How the signals carried by these feature selective neurons are integrated into coherent object representations is unknown and stands as one of the central unsolved questions in neurobiology. Insight into the mechanisms that solve this problem can be gained by carefully analyzing the temporal properties of perceptual integration at the psychophysical and neuronal levels. We will pursue this strategy, focusing on a simple and well-defined case of feature integration: the conjoining of two of the most basic and well studied features in vision: color and orientation. The central objective of the current proposal is to understand how the visual system conjoins these features. This objective will be met in the following specific aims. Aim 1. Compare the temporal resolution of the visual system for color, orientation and conjunctions of these two features, at the perceptual level and in BOLD in humans, and at the neuronal level in monkeys. Aim 2. Characterize the temporal dynamics of tuning for color and orientation, their dependence on luminance contrast, and quantify any changes in these properties under naturalistic visual stimulation. Aim 3. Test whether spatial attention plays a role in the integration of color and orientation. Relevance: Our current lack of knowledge about the mechanisms of feature integration represents a significant gap in our understanding of the pathology of disorders in which the perception of objects is impaired, such as simultagnosia, prosopagnosia, integrative visual agnosia, Balint's syndrome, and object- centered impairments associated with neglect. Filling this gap will provide understanding that will help in the interpretation and treatment of these and related disorders. The proposed experiments will close this gap by (1) characterizing the temporal resolution of the neural mechanisms that mediate feature integration, (2) developing and testing mathematically rigorous models of the neural computations that mediate a simple and well defined form of feature integration, and (3) determining whether or not attention plays a role in the formation of feature conjunctions.