Neural mechanisms of color

神经活动、感知和认知之间的联系还知之甚少。这项建议 推进颜色作为模型系统，以填补这些知识的空白。颜色是一个基本特征 视觉经验，以及许多关于如何从眼睛锥信号编码， 传递到大脑皮层但令人惊讶的是， 这些信号带来感知的颜色并指导感知决策。两个相互竞争 已经提出了解码方案：间隔码，其需要细胞群 与尖锐的色彩调谐，共同涵盖所有的色彩空间，再加上一个赢家- 采取所有的规则;和人口代码，这需要至少两组颜色调整 神经元，再加上加权平均规则。目前还不清楚哪些神经元组内的 大脑皮层也参与其中一个提示来自下颞叶皮层（IT）的病变， 恒河猴，这导致严重的色盲类似于色盲， 伴随着人类的某些脑中风IT是一个广泛的组织区域， 在对象编码的许多方面，IT的功能组织也知之甚少。 如果没有这些信息，几乎不可能知道哪些神经元最有可能 有助于色彩处理。可能的组织方案包括模块化模式 包括唯一专用区域;分布式处理模型;或混合模型， 由一系列分级阶段组成，每个阶段都包括一个完整的功能补充， 分区域.目标1要求一系列功能性磁共振成像（fMRI） 在警觉的猴子中进行的实验将确定IT中颜色编码区域的分布， 它们的功能连接性和与其他功能定义区域的关系，以测试 目标2概述了fMRI引导的微电极记录 当猴子执行颜色任务时，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关系，并确定两者中的哪一个 解码方案，间隔或人口，是在IT实现。研究将揭示 感知和认知从神经回路活动中产生的原理。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 人类和猴子之间的高级区域的关系，这是必要的， 用猴子作为人类视觉和疾病的模型。

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.