RUI: Color processing in inferior temporal cortex of macaque monkey

大脑是如何处理感觉信号来产生感知和知识的？这个项目将颜色作为解决这一根本问题的首要系统。与流行的观点相反，颜色的体验并不是由刺激的物理特性直接预测的，这暴露了神经系统在将眼睛接收的信息转化为行为方面所起的重要作用。人们认为，颜色和视觉的其他方面一样，是由一系列大脑结构计算出来的。但这些结构的位置和它们为产生颜色而执行的计算尚不清楚。这项拟议的工作利用脑功能成像(FMRI)的进步来识别参与最高级别颜色处理的区域，并将确定这些区域如何相互连接以及视觉通路的其余部分。在严格控制的实验条件下，这项研究将使用fMRI引导的瞬时药物阻断来确定哪些大脑区域是执行哪些颜色任务所必需的。结果被预测为，阻断视觉处理层次中较低的颜色处理区域将损害不太复杂的颜色行为，如颜色辨别，而阻断较高级别的大脑区域将损害对认知要求更高的行为，如颜色分类。这一研究环境代表了一所文科女子S学院与一家主要研究机构之间的独特合作，并将为培训下一代女性科学家掌握最先进的神经科学技术提供难得的机会。这项工作的成果将通过同行评议的出版物、在国家和国际会议上的发言以及世界科学节等大众媒体广泛传播，为提高科学技术研究的普遍素养提供了一种机制。此外，这些技巧、问题和结果将被纳入韦尔斯利学院的本科课程，并在课程网站上免费提供。(http://academics.wellesley.edu/Neuroscience/Neuro320/)Much知道颜色信号是如何由视网膜编码并传递到大脑皮层的，但令人惊讶的是，人们对这些信号解码产生感知颜色的机制知之甚少。广泛的前期工作表明，颜色反应局限于下颞叶皮质，这是大脑中已知的参与感知和识别物体的一大片区域。所提出的实验验证了这样一个假设，即颞叶下部皮质的颜色偏向区域组成了一个相互连接的层级网络，这是颜色感知所必需的。具体地说，这项工作将检查后部偏色区域解码颜色外观(色调、饱和度)的程度，而前部区域计算更多的认知现象，例如我们将连续色调空间划分为离散类别的能力。这一假设将使用功能磁共振成像、心理物理学、功能磁共振引导的药物灭活和功能磁共振引导的示踪剂注射的组合进行验证。这项工作将回答两个基本问题：1.不同的颜色偏向区域在多大程度上是颜色辨别和颜色分类行为所必需的？2.颜色偏向区域是否相互连接，如果是，连接模式是否反映了沿颞极从后到前的预测等级？解决这些问题不仅将增进我们对颜色处理的理解，还将揭示大脑皮层如何处理信息的一般原理。这一新知识将推动更具生物学合理性的机器视觉系统的发展。这项工作将产生广泛的影响，既来自科学发现，也来自辅助活动，如指导从事STEM研究的本科生女性和代表性不足的少数群体；扩大跨机构合作伙伴关系；编制和传播本科生神经科学课程材料；提高公众的科学素养；以及加强艺术与科学之间的联系。

How does the brain process sensory signals to generate perception and knowledge? This project advances color as a premier system with which to tackle this fundamental question. Contrary to popular opinion, the experience of color is not directly predicted by physical properties of stimuli, exposing the important role that the nervous system plays in transforming information received by the eye into behavior. It is thought that color, like other aspects of vision, is computed by a series of brain structures. But the location of these structures and the computations they perform to bring about color are not known. The proposed work exploits advances in functional brain imaging (fMRI) to identify regions involved in the highest levels of color processing, and will determine how these regions are connected to each other and the rest of the visual pathway. Under carefully controlled experimental conditions, the research will determine which brain regions are necessary for which color tasks using fMRI-guided transient pharmacological blockade. The results are predicted to show that blockade of color-processing regions lower in the visual-processing hierarchy will impair less sophisticated color behaviors such as color discrimination, while blockade of higher-order brain regions will impair more cognitively demanding behaviors such as color categorization. The research environment represents a unique collaboration between a liberal arts women?s college and a major research institution, and will provide exceptional opportunities to train the next generation of female scientists in the most advanced neuroscientific techniques. The results of the work will be widely disseminated through peer-reviewed publications, presentations at national and international conferences, and popular media such as the World Science Festival, providing a mechanism to enhance general literacy in science and technology research. In addition, the techniques, questions and results will be incorporated into undergraduate curricula at Wellesley College and freely available on course websites. (http://academics.wellesley.edu/Neuroscience/Neuro320/)Much is known about how color signals are encoded by the retina and transmitted to the cerebral cortex, but surprisingly little is known about the mechanisms that decode these signals to bring about perceived colors. Extensive preliminary work suggests that color responses are localized within inferior temporal cortex, a large area of the brain known to be involved in the perception and recognition of objects. The proposed experiments test the hypothesis that the color-biased regions of inferior-temporal cortex comprise an interconnected hierarchical network that is necessary for color perception. Specifically, the work will examine the extent to which posterior color-biased regions decode color appearance (hue, saturation) and anterior regions compute more cognitive phenomena such as our ability to carve the continuous hue space into discrete categories. The hypothesis will be tested using a combination of functional magnetic resonance imaging, psychophysics, fMRI-guided pharmacological inactivation, and fMRI-guided tracer injections. The work will answer two fundamental questions: 1. To what extent are different color-biased regions necessary for color-discrimination and color-categorization behavior? 2. Are the color-biased regions connected, and if so, does the pattern of connectivity reflect the predicted hierarchy from posterior to anterior along the temporal pole? Addressing these questions will not only advance our understanding of color processing, but will uncover general principles that underlie how the cerebral cortex processes information. This new knowledge will promote the development of more biologically plausible machine vision systems. The work will yield broad impacts both from scientific discoveries and from complementary activities such as the mentorship of undergraduate women and underrepresented minorities engaged in STEM research; expansion of cross-institutional partnerships; development and dissemination of undergraduate neuroscience course materials; enhancement of public scientific literacy; and strengthening of connections between arts and sciences.