Visually guided behaviors such as optomotor and optokinetic responses, phototaxis, and prey capture are crucial for survival in zebrafish and become apparent after just a few days of development. Color vision, which in zebrafish is based on a spatially anisotropic tetrachromatic retina, provides an additional important component of world representation driving fundamental larval behaviors. However, little is known about the central nervous system (CNS) circuitry underlying color vision processing downstream of the retina, and its activity correlates with behavior. Here, we used the transparent larva of zebrafish to image CNS neurons and their activity in response to colored visual stimuli. To investigate the processing of chromatic information in the zebrafish larva brain, we mapped with cellular resolution, spectrally responsive neurons in the larva encephalon and spinal cord. We employed the genetically encoded calcium indicator GCaMP6s and two-photon microscopy to image the neuronal activity while performing visual stimulation with spectrally distinct stimuli at wavelengths matching the absorption peaks of the four zebrafish cone types. We observed the presence of a high number of wavelength-selective neurons not only in the optic tectum, but also in all other regions of the CNS, demonstrating that the circuitry involved in processing spectral information and producing color-selective responses extends to the whole CNS. Our measurements provide a map of neurons involved in color-driven responses, revealing that spectral information spreads in all regions of the CNS. This suggests the underlying complexity of the circuits involved and opens the way to their detailed future investigation.

中文翻译：

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彩色视觉刺激引起斑马鱼幼虫中枢神经系统的光谱调谐神经元反应

视觉引导的行为，如光运动和光动反应、趋光性和猎物捕获对于斑马鱼的生存至关重要，并且在发育几天后就会变得明显。斑马鱼的色觉基于空间各向异性的四色视网膜，提供了驱动基本幼虫行为的世界表征的额外重要组成部分。然而，人们对视网膜下游颜色视觉处理背后的中枢神经系统 (CNS) 电路知之甚少，其活动与行为相关。在这里，我们使用斑马鱼的透明幼虫对 CNS 神经元及其响应彩色视觉刺激的活动进行成像。为了研究斑马鱼幼虫大脑中色度信息的处理，我们用细胞分辨率进行了映射，幼虫脑和脊髓中的光谱响应神经元。我们采用基因编码的钙指示剂 GCaMP6s 和双光子显微镜对神经元活动进行成像，同时在与四种斑马鱼锥体类型的吸收峰匹配的波长下用光谱不同的刺激进行视觉刺激。我们观察到大量波长选择性神经元不仅存在于视顶盖中，而且存在于 CNS 的所有其他区域，这表明参与处理光谱信息和产生颜色选择性反应的电路延伸到整个 CNS . 我们的测量提供了一张涉及颜色驱动反应的神经元图，揭示了光谱信息在 CNS 的所有区域中传播。