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

项目总结/摘要 我们周围的环境是非常丰富的光谱信息，这赋予了一个有价值的彩色 视觉感知的维度。为了具有颜色视觉的能力，生物体必须能够 执行必要的计算以比较不同光谱组成的光。波长 比较发生在颜色对手神经元中，它们对波长的反应极性相反， 光谱的不同部分。尽管我们对大脑中的颜色敏感性的理解有了进步， 颜色对立信号被转换以产生在更高的皮层区域中观察到的色调特异性 仍然无法解释此外，波长信息如何在整个视野中整合 为色觉提供空间维度是一种知之甚少的现象。该项目旨在 研究遗传上易处理的黑腹果蝇中的颜色通路，因为这些回路 才刚刚开始被描述。果蝇为操纵神经元活动提供了大量的遗传工具 和一个简单的大脑，使这些电路易于处理。果蝇有波长硬件 与表达视紫红质的波长特异性光感受器（称为R7和R8）相比， UV、绿色和蓝色光。有越来越多的证据表明，颜色依赖性确实存在于大脑中， 果蝇，产生于R7/R8的轴突。目标1将确定信号如何在 光感受器，以产生双光子钙成像的R7/R8轴突在各种 遗传背景，包括突变体、成对拯救和具有细胞特异性沉默的品系。目标2将 阐明果蝇光感受器中双折射的空间性质，利用这一事实， 空间模式的刺激将揭示潜在的中心-周围机制时，配对功能 R7/R8轴突的成像。最后，目标3将探索光谱和空间信息的编码， 下游大脑区域准备好接收来自光感受器的信号，并进一步传输这些信号， 向大脑中央区域发送信号有证据表明，这些信息最终会通知诸如对象 识别和空间定位。确定用于空间色彩处理的电路机制如何 出现并将信息传递到果蝇的高级大脑区域将提供对 脊椎动物的颜色通路，因为这两个系统采用类似的机制，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.