QUANTITATIVE STUDIES OF VISUAL PATHWAYS

这里提出的工作的总体目标是了解中央 视觉通路分析有关色度和空间的信息 对象的特性。提出了三个主要项目。通过一个 生理和心理物理实验相结合，这些尝试 为了阐明视觉的某一特定方面与其 潜在的生理学。 第一个项目将探索色度对立面 在猕猴P细胞的感受野中，LGN并非通过选择而产生 锥体类，但通过中心接收来自单个锥体的输入， 随着环绕不分青红皂白地利用L和M视锥的输入。 生理测量将使用适当的干涉条纹 颜色来分析锥体输入在接收区域的组织 P细胞处于不同的偏心状态。心理物理实验来估计 色度相反的机制对图像进行采样的密度 将探索这样的推论，即大脑中的侏儒P细胞稀少 周边是我们色觉受损的原因。 第二个项目将使用静默替换方法来检查 单个锥体通道中的增益控制机制与 噪声，以控制P细胞中的颜色敏感性。在此期间进行的工作 前一段时间的支持显示，在获得 背景色度变化后的P细胞反应，并显示 噪声的变化与这些相互作用，调节了对 刺激物。因为背景色度的变化也导致了长时间的 P细胞持续放电的持久变化，该项目还将 研究这些变化是如何由皮质神经元表达的。 第三个项目将探索这样一个想法，即大脑中神经元的行为 视觉皮质的早期阶段解释了知觉的独特性 视觉纹理。这些实验将考察神经元(特别是 V1和V2中的复杂单元格)响应于 心理物理学研究。在前一年期间所做的工作 支持建议对皮质的作用有更全面的理解 细胞将需要使用利用非线性方面的视觉刺激 他们的行为。纹理识别的研究应该直接得到 这是因为对纹理的感知辨别似乎需要 具有与复杂细胞中发现的特性类似的非线性机制。

The overall aim of the work proposed here is to understand how central visual pathways analyze information about the chromatic and spatial properties of objects. Three major projects are proposed. Through a combination of physiological and psychophysical experiments these attempt to elucidate the connection between a particular aspect of vision and its underlying physiology. The first project will explore the possibility that the chromatic opponency in receptive fields of P-cells of macaque LGN arises not through selection of cone classes, but through the center receiving input from a single cone, with the surround drawing indiscriminately on inputs from L and M cones. The physiological measurements will use interference fringes of appropriate color to analyze the organization of cone inputs in the receptive fields of P-cells at various eccentricities. Psychophysical experiments to estimate the density with which chromatically opponent mechanisms sample the image will explore the corollary that a paucity of midget P-cells in the periphery accounts for our impaired color vision. The second project will use silent-substitution methods to examine how gain-controlling mechanisms in individual cone pathways act together with noise to control chromatic sensitivity in P-cells. Work undertaken during the previous period of support revealed paradoxical changes in the gain of P-cell responses following changes in background chromaticity, and showed that changes in noise interact with these in regulating detectability of stimuli. Because changes in background chromaticity also led to long- lasting changes in maintained discharge of P-cells, the project will also examine how these changes are expressed by cortical neurons. The third project will explore the idea that the behavior of neurons in the early stages of visual cortex accounts for the perceptual distinctiveness of visual textures. The experiments will examine how neurons (particularly complex cells) in V1 and V2 respond to visual textures of types employed in psychophysical studies. Work undertaken during the previous period of support suggested that a fuller understanding of the roles of cortical cells will require the use of visual stimuli that tap the nonlinear aspects of their behavior. The study of texture discrimination should get directly at this because perceptual discrimination of textures appears to require nonlinear mechanisms with properties like those found in complex cells.