COLOR PROCESSING IN HUMAN CORTEX

人类皮层的颜色处理

• 批准号: 6179183
• 负责人: STEPHEN A. ENGEL
• 金额: $ 15.2万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-30 至 2004-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6179183
• 关键词: behavioral /social science research tag; bioimaging /biomedical imaging; clinical research; color visions; computational neuroscience; cone cell; form /pattern perception; functional magnetic resonance imaging; human subject; lateral geniculate body; neural information processing; orientation; retinal adaptation; space perception; stimulus /response; visual cortex; visual pathways; visual perception

The goal of this project is to advance understanding of how color is represented in cortex. While the first stages of color perception are well understood, much less is known about subsequent processing. The general aim of this proposal is to identify neural populations in cortex that support a second stage of processing, the opponent colors representation. Perceptual studies reveal that this representation encodes color as three combinations of cone signals, encoding relative amounts of red and green, blue and yellow, and light and dark. These perceptual mechanisms: 1) signal specific, linear combinations of cone signals; 2) maintain their color properties even as spatial pattern changes; 3) change their responsiveness independently of each other; 4) are selective for spatial frequency and orientation; 5) pass signals to other, non-cardinal color mechanisms. But the neural bases of opponent colors mechanisms remain unkown. While parvocellular neurons in the lateral geniculate nucleus receive opposing cone inputs, these cells fail to show properties 2 and 3, listed above. Some neurons in areas V2-V4 are tuned for non-cardinal colors, and are selective for spatial frequency, but the crucial experiments linking these neurons to perceptual results have not been performed. The work proposed here is designed to identify neural populations that can account for the opponent colors mechanisms. The responsiveness of human visual areas and LGN to stimuli of many colors will be measured using functional magnetic resonance imaging. A series of experiments will test for the 5 key properties of opponent color mechanisms. First, the linearity of color responses will be tested. Next, color responses will be measured at several spatial frequencies and in the presence of adapting stimuli, testing for properties 2, 3, and 5. Finally, measurements of transfer of adaptation will test for property 4. Visual areas whose responses show these properties are likely to contain populations of neurons that support color perception. Populations showing the different properties will most likely be found in different visual areas, helping to reveal the specific role of each area in the computations that underly color perception, and testing computational theories of color perception.

这个项目的目标是促进对颜色如何在皮层中表现的理解。 虽然颜色感知的第一阶段已经很好地理解，但对后续处理的了解要少得多。 这个建议的总体目标是识别皮层中支持第二阶段处理的神经群体，即对手颜色表征。 知觉研究表明，这种表征将颜色编码为锥细胞信号的三种组合，编码红色和绿色、蓝色和黄色以及浅色和深色的相对量。 这些感知机制：1）视锥信号的信号特异性线性组合; 2）即使在空间模式改变时也保持它们的颜色特性; 3）彼此独立地改变它们的响应性; 4）对于空间频率和取向是选择性的; 5）将信号传递到其他非基本颜色机制。 但是对立颜色机制的神经基础仍然未知。 虽然外侧膝状体核中的小细胞神经元接受相反的锥体输入，但这些细胞未能显示出上述特性2和3。 V2-V4区域的一些神经元对非主色进行调谐，并且对空间频率具有选择性，但是将这些神经元与感知结果联系起来的关键实验尚未进行。 这里提出的工作旨在识别可以解释对手颜色机制的神经种群。 人类视觉区域和LGN对许多颜色刺激的反应将使用功能性磁共振成像来测量。 一系列的实验将测试对手颜色机制的5个关键属性。 首先，将测试颜色响应的线性。 接下来，将在几个空间频率和适应刺激的存在下测量颜色响应，测试属性2，3和5。 最后，适应转移的测量将测试性质4。 显示这些特性的视觉区域可能包含支持颜色感知的神经元群体。显示不同属性的人群很可能在不同的视觉区域中找到，这有助于揭示每个区域在色彩感知计算中的特定作用，并测试色彩感知的计算理论。