COLOR PROCESSING IN HUMAN CORTEX

人类皮层的颜色处理

• 批准号: 2902576
• 负责人: STEPHEN A. ENGEL
• 金额: $ 14.76万
• 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/2902576
• 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在皮质中如何表现的理解。虽然颜色知觉的第一个阶段是众所周知的，但对随后的处理知之甚少。这一提议的总体目标是识别大脑皮层中支持第二阶段加工的神经群组，即对手颜色表征。知觉研究表明，这种表示将颜色编码为锥体信号的三种组合，编码了红色和绿色、蓝色和黄色以及明和暗的相对量。这些感知机制：1)信号特定的锥体信号的线性组合；2)即使在空间图案改变时也保持它们的颜色属性；3)彼此独立地改变它们的响应性；4)对空间频率和方向是选择性的；5)将信号传递给其他非基数颜色机制。但对手颜色机制的神经基础仍不清楚。虽然外侧膝状核中的小细胞神经元接受相反的锥体输入，但这些细胞无法表现出上面列出的特性2和特性3。V2-V4区的一些神经元被调谐为非基色，并对空间频率具有选择性，但将这些神经元与知觉结果联系起来的关键实验尚未进行。这里提出的工作是为了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对多种颜色刺激的反应性将使用功能磁共振成像进行测量。一系列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，在存在适应刺激的情况下，颜色反应将在几个空间频率上进行测量，测试属性2、3和5。最后，适应性转移的测量将测试属性4。反应显示这些属性的视觉区域可能包含支持颜色感知的神经元群体。显示不同特性的种群很可能在不同的视觉区域被发现，这有助于揭示每个区域在低于颜色感知的计算中的特定角色，并测试颜色感知的计算理论。