Spectral and spatial processing of wavelength information in the Drosophila visual system

项目摘要/摘要 我们周围的环境具有极其丰富的光谱信息，这赋予了我们一种宝贵的色度 视觉感知的维度。为了有颜色视觉的能力，有机体必须能够 执行必要的计算以比较不同光谱组成的光。波长 比较发生在与颜色相反的神经元中，它们对波长的反应是相反的 光谱的不同部分。尽管我们对大脑中颜色对抗的理解取得了进展，但 颜色相反的信号被转换以产生在较高皮质区观察到的色调特异性 仍然完全无法解释。此外，波长信息是如何跨视场整合的 为颜色视觉提供空间维度是一个鲜为人知的现象。该项目旨在 检查遗传易驯化的生物体黑腹果蝇的颜色通路，就像这些回路 只是刚刚开始被描述。果蝇为操控神经元活动提供了大量的遗传工具 和一个简单的大脑，让这些电路变得容易控制。果蝇有波长的硬件 与波长特异性光感受器(称为R7和R8)表达的视紫红质对 紫外光、绿光和蓝光。越来越多的证据表明，颜色对抗确实存在于人的大脑中 果蝇，出现在R7/R8的轴突中。目标1将确定如何在以下级别组合信号 利用R7/R8轴突的双光子钙成像研究光感受器引起的对抗性 遗传背景，包括突变、成对拯救和具有细胞特异性沉默的品系。目标2将 解释果蝇光感受器中对抗性的空间性质，利用以下事实 当与功能性刺激配对时，空间图案化刺激将揭示潜在的中心-环绕机制 R7/R8轴突的成像。最后，目标3将探索光谱和空间信息在 大脑下游区域准备接收来自光感受器的信号，并进一步传递这些信号 向中央大脑区域发出信号。有证据表明，这些信息最终会通知对象等任务 识别和空间定位。确定用于空间色度处理的电路机制 出现并将信息传递给果蝇的高级大脑区域将为深入了解 脊椎动物的颜色通路，因为两个系统都使用相似的机制来有效地处理视觉 信息。

Project Summary / Abstract Our surroundings are extremely rich in spectral information, which confers a valuable chromatic dimension to visual perception. In order to have the capacity for color vision, an organism must be able to perform the necessary computations to compare light of different spectral compositions. Wavelength comparison takes place in color opponent neurons, which respond with opposite polarity to wavelengths in different parts of the spectrum. Despite advances in our understanding of color opponency in the brain, how color opponent signals are transformed to give rise to the hue specificity observed in higher cortical regions remains completely unexplained. Furthermore, how wavelength information is integrated across the visual field to provide a spatial dimension to color vision is a poorly understood phenomenon. This project aims to examine color pathways in the genetically tractable organism Drosophila melanogaster, as these circuits have only just begun to be described. Drosophila provide an arsenal of genetic tools to manipulate neuronal activity and a simple brain that makes these circuits tractable. Fruit flies have the hardware for wavelength comparison, with wavelength-specific photoreceptors (called R7s and R8s) expressing rhodopsins sensitive to UV, green, and blue light. There is mounting evidence that color opponency is indeed present in the brain of the fruit fly, arising in the axons of R7/R8. Aim 1 will determine how signals are combined at the level of photoreceptors to give rise to opponency by using two-photon calcium imaging of R7/R8 axons in a variety of genetic backgrounds, including mutants, pairwise rescues, and lines with cell-specific silencing. Aim 2 will elucidate the spatial nature of opponency in Drosophila photoreceptors, taking advantage of the fact that spatially patterned stimuli will reveal potential center-surround mechanisms when paired with functional imaging of R7/R8 axons. Finally, Aim 3 will explore the encoding of both spectral and spatial information in downstream brain areas poised to both receive signals from photoreceptors, and to further transmit these signals to central brain regions. There is evidence that this information eventually informs tasks such as object recognition and spatial orientation. Determining how circuit mechanisms for spatio-chromatic processing emerge and convey information to higher brain areas in Drosophila will provide insight into the workings of vertebrate color pathways, as both systems employ similar mechanisms to effectively process visual information.