Neural mechanisms of color

人们对神经活动、知觉和认知之间的联系知之甚少。这项建议 将颜色作为一种模型系统来填补这些知识空白。颜色是一项基本功能 视觉体验，而且关于来自眼睛的视锥信号是如何编码和 传输到大脑皮层。但令人惊讶的是，人们对解码的机制知之甚少 这些信号带来了感知的颜色并引导了感知的决定。两个竞争对手 已经提出了译码方案：需要一组信元的间隔码 带有清晰的色调，共同涵盖所有颜色空间，再加上获胜者- 全食规则；以及人口代码，它至少需要两组颜色调整 神经元，再加上加权平均规则。目前尚不清楚脑组织中的哪些神经元 大脑皮层受累。其中一个提示来自于中国人的颞叶下皮质(IT)病变 恒河猴，它会导致严重的色盲，类似于 伴随着人类的某些脑中风。它是一个牵涉到的组织的扩张区域 在对象编码的许多方面，人们对IT的功能组织知之甚少。 如果没有这些信息，我们几乎不可能知道哪些神经元最有可能 为色彩处理做出贡献。可能的组织方案包括模块化模型 包括独特的专业领域；分布式处理模型；或混合模型， 由一系列分层阶段组成，每个阶段都包含完整的功能 子区域。AIM 1需要一组功能磁共振成像(FMRI) 在警觉的猴子身上进行的实验将决定IT中颜色编码区的分布， 它们的功能连通性以及与其他功能定义区域的关系，以测试 模型说明了IT的组织方式。AIM 2概述了fMRI引导的微电极记录 在猴子执行颜色任务时，将IT颜色区域与微刺激配对，以测试 神经活动和感知颜色之间的因果联系，并确定两者中的哪一个 在IT中实现了区间或总体的解码方案。这项研究将揭示 感知和认知从神经回路的活动中产生的原理。这 了解精神疾病的病因、诊断和治疗需要信息。 以及损害认知和知觉的中风。此外，这项工作将建立 人与猴子之间的高阶区关系，这是秩序所必需的 用猴子作为人类视力和疾病的模型。

The links between neural activity, perception and cognition are poorly understood. This proposal advances color as a model system to fill these gaps in knowledge. Color is an essential feature of visual experience, and much is known about how cone signals from the eye are encoded and transmitted to the cortex. But surprisingly little is known about the mechanisms that decode these signals to bring about perceived colors and guide perceptual decisions. Two competing decoding schemes have been proposed: an interval code, which requires a population of cells with sharp chromatic tuning that together encompass all color space, coupled with a winner- take-all rule; and a population code, which needs at minimum two groups of color-tuned neurons, coupled with a weighted-average rule. It is unclear which groups of neurons within the cerebral cortex are involved. One hint comes from lesions of inferior temporal cortex (IT) in rhesus monkeys, which cause profound color blindness similar to the achromatopsia that accompanies certain cerebral strokes in humans. IT is an expansive region of tissue implicated in many aspects of object coding, and the functional organization of IT is poorly understood. Without this information, it is almost impossible to know which neurons are the most likely to be contributing to color processing. Possible organizational schemes include a modular model comprising uniquely specialized areas; a distributed-processing model; or a hybrid model, consisting of a series of hierarchical stages, each comprising a full complement of functional subregions. Aim 1 calls for a battery of functional magnetic resonance imaging (fMRI) experiments in alert monkey that will determine the distribution of color-coding regions in IT, their functional connectivity and relationship to other functionally defined regions to test which model accounts for the organization of IT. Aim 2 outlines fMRI-guided microelectrode recordings of IT color regions paired with microstimulation while monkeys perform color tasks, to test the causal link between neural activity and perceived color, and to determine which of the two decoding schemes, interval or population, is implemented in IT. The research will uncover principles by which perception and cognition emerge from the activity of neural circuits. This information is required to understand the etiology, diagnosis, and treatment of mental illnesses and strokes that impair cognition and perception. Moreover, the work will establish the relationship of higher-order areas between humans and monkeys, which is necessary in order to use monkeys as models of human vision and disease.