The Tuning for Complex Visual Stimuli in V1

描述（由申请人提供）：这项工作的长期目标是了解视觉形式感知的神经机制。本研究旨在研究初级视皮层（V1）对中等复杂视觉刺激（如平滑轮廓、连接点和纹理边界）的处理。最近的证据表明，V1不仅仅是一组过滤器，它从所有视觉输入中被动地提取最简单的元素（例如短的定向线段），就像以前认为的那样。相反，复杂刺激的基本成分相互作用强烈，产生V1反应，可能与对单个成分的反应截然不同。目前的项目是为了测试的假设，这种复杂的视觉处理可以预测的柱状架构和内在的电路VI。特别地，提出了皮质柱调谐到复杂刺激的元素分量（例如，在特定视网膜位置、取向、颜色对比度等处的线段）。通过本征V1电路以可预测的方式促进和抑制彼此，以产生对复合整体的调谐。此外，任何给定的V1神经元的复杂调谐可以从其在皮层上的地理位置相对于由所讨论的复杂刺激激活的列来预测。这一假设将通过研究V1处理不同的家庭复杂的刺激，包括光滑的轮廓，路口和纹理边界，感知场景分割的重要性。本研究将使用警戒猴V1中光学成像和电极记录的组合。光学成像将允许映射神经元对每个复杂刺激及其单个成分做出反应的皮层位置。电极记录和交叉相关性，由光学图像引导，将用于测量同一组神经元之间的皮质内相互作用。基于这些相互作用计算的复杂调谐可以与测量值进行比较，从而验证我们的假设。光学成像和电极记录的建议相结合，将有可能阐明的V1调谐，一个目标，是不能通过单独的电极记录的皮质机制的几何形状。这项研究的结果将提供一个广泛的框架，了解复杂的视觉刺激，临床应用，包括视觉假体的设计为盲人的一个重要步骤的皮层处理。

DESCRIPTION (provided by applicant): The long-term goal of this work is to understand the neural mechanisms of visual form perception. The current project aims to study the processing of modestly complex visual stimuli such as smooth contours, junctions and texture boundaries in primary visual cortex (V1). Recent evidence suggests that V1 is much more than just a bank of filters that passively extracts the simplest elements (e.g. short oriented line segments) from all visual input, as was earlier believed. Rather, the elemental components of complex stimuli interact strongly with each other to give V1 responses that could differ dramatically from the responses to the individual components. The current project is intended to test the hypothesis that such complex visual processing can be predicted from the columnar architecture and intrinsic circuitry of VI. In particular, it is proposed that cortical columns tuned to elemental components of a complex stimulus (e.g. line segments at particular retinotopic positions, orientations, color contrast etc.) facilitate and inhibit each other in predictable ways through intrinsic V1 circuitry to generate tuning for the composite whole. Further, that the complex tuning of any given V1 neuron can be predicted from its geographical position on cortex relative to columns activated by the complex stimulus in question. This hypothesis will be tested by studying the V1 processing for different families of complex stimuli including smooth contours, junctions and texture boundaries that are perceptually important for scene segmentation. A combination of optical imaging and electrode recordings in alert monkey V1 will be used for this study. Optical imaging will allow for mapping the cortical positions of neurons responding to each complex stimulus and its individual components. Electrode recordings and cross correlations, guided by optical images, will be used to measure the intracortical interactions between the same groups of neurons. The complex tuning computed on the basis of these interactions can then be compared with the measured values and thus test our hypothesis. The proposed combination of optical imaging and electrode recording will make it possible to elucidate the geometry of cortical mechanisms underlying V1 tuning, a goal that is not reachable through electrode recordings alone. The results of this study will provide a broad framework for understanding the cortical processing of complex visual stimuli, an essential step for clinical applications including the design of visual prostheses for the blind.