Neural circuit mechanisms for color vision

项目摘要（父R01） 色觉是我们感知世界的一个重要方面，它增强了我们对复杂物体的识别能力。 视觉场景，并允许我们分配他们的身份和质量。颜色是如何在大脑中编码的？ 尽管经过几十年的研究，这个问题仍然没有答案。人们普遍认为， 神经元对光谱不同部分的波长有相反的极性反应， 色觉障碍然而，颜色对手神经元信号如何组合以产生颜色特异性 神经元，具有窄光谱敏感性，以及这些神经元如何有助于颜色感知是未知的。 分析遗传上易处理的有机体中的颜色回路对于回答这些问题至关重要。果蝇 melanogaster提供了一个强大的系统来研究紧凑的大脑如何解决颜色编码的问题， 结合对细胞类型特异性神经群体的遗传访问，明确定义的神经解剖结构， 复杂的行为此外，脊椎动物和无脊椎动物的视觉系统呈现出许多功能性特征。 相似之处事实上，这些不同的系统在解决视觉处理问题方面表现出收敛性， 激励我们的调查在一个简单的模型，与提取相关性的基本原则的意图 到哺乳动物系统。果蝇能够辨别颜色，并具有必要的硬件， 波长比较：四种类型的锥状光感受器，每种都表达独特的窄带 视紫红质具有不同的波长敏感性，范围从UV到绿色。然而，光谱信息 从这些光感受器是在大脑中处理是未知的，是这个建议的重点。我们将使用 遗传神经操作技术、体内双光子成像、电生理学和行为测定 通过定量分析和建模，以确定计算算法和神经网络 控制颜色视觉的机制。目标1将询问存在什么样的幽灵对手机制 果蝇和确定神经元的身份和突触的相互作用在底层电路。我们将在 此外，生成工具来破坏彩色对手信号。Aim 2将使用连接组学数据， 跟踪方法来定义和功能性地表征颜色光感受器的突触后的颜色回路。我们 将研究颜色对手信号如何整合，以产生更高阶的颜色神经元。目标3将 描述这些回路中神经元的反应如何支持先天和后天的颜色引导 行为，标志着一个实验性的努力，以绘制之间的因果关系的颜色顺应性，颜色电路和颜色 感知，一种在经典的、非遗传易处理的色觉模型中一直很困难的方法。 这些研究将提供一个详细的了解光谱信息是如何处理在苍蝇的大脑， 作为一个指导，以调查波长计算基础的颜色视觉在大脑中的更复杂的 动物

Project Summary (parent R01) Color vision is an important aspect of our perception of the world, enhancing our recognition of objects in complex visual scenes and allowing us to assign them an identity and quality. How are colors encoded in the brain? Despite decades of research, this question remains unanswered. It is widely accepted that color opponent neurons, responding with opposite polarity to wavelengths in different parts of the spectrum, are the building blocks for color vision. However, how color opponent neuron signals are combined to give rise to hue-specific neurons, with narrow spectral sensitivity, and how these neurons contribute to color perception is unknown. Analyses of color circuits in a genetically tractable organism are critical to answering these questions. Drosophila melanogaster provides a powerful system to investigate how a compact brain solves the problem of color coding, combining genetic access to cell-type-specific neural populations, a well-defined neural anatomy, and sophisticated behaviors. Moreover, vertebrate and invertebrate visual systems present many functional similarities. The fact that these diverse systems show convergence in solutions to visual processing problems motivates our investigation in a simple model, with the intention of extracting fundamental principles of relevance to mammalian systems. Fruit flies are capable color discrimination and have the hardware necessary for wavelength comparison: four types of cone-like photoreceptors each expressing a unique narrow-band rhodopsin of different wavelength sensitivity, ranging from UV to green. However, the way spectral information from these photoreceptors is processed in the brain is unknown and is the focus of this proposal. We will use genetic neural manipulation techniques, in vivo two-photon imaging, electrophysiology, and behavioral assays augmented by quantitative analysis and modeling, to identify the computational algorithms and neural mechanisms that govern color vision. Aim 1 will ask what kind of spectrally opponent mechanisms exist in Drosophila and determine the identity of neurons and synaptic interactions in the underlying circuits. We will, in addition, generate tools to disrupt color opponent signals. Aim 2 will use connectomics data in conjunction with tracing methods to define and functionally characterize color circuits postsynaptic to color photoreceptors. We will investigate how color-opponent signals are integrated to give rise to higher order color neurons. Aim 3 will characterize how the response of neurons in these circuits support both innate and learned color-guided behaviors, marking an experimental effort to draw a causal link between color opponency, color circuits and color perception, an approach that has been difficult in classical, non-genetically tractable, models for color vision. These studies will provide a detailed understanding of how spectral information is processed in the fly brain and serve as a guide to investigate wavelength computations underlying color vision in the brain of more complex animals.