Max Planck Institute of Neurobiology, Department of Systems and Computational Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany.
J Neurophysiol. 2010 Mar;103(3):1646-57. doi: 10.1152/jn.00950.2009. Epub 2010 Jan 20.
Motion vision is essential for navigating through the environment. Due to its genetic amenability, the fruit fly Drosophila has been serving for a lengthy period as a model organism for studying optomotor behavior as elicited by large-field horizontal motion. However, the neurons underlying the control of this behavior have not been studied in Drosophila so far. Here we report the first whole cell recordings from three cells of the horizontal system (HSN, HSE, and HSS) in the lobula plate of Drosophila. All three HS cells are tuned to large-field horizontal motion in a direction-selective way; they become excited by front-to-back motion and inhibited by back-to-front motion in the ipsilateral field of view. The response properties of HS cells such as contrast and velocity dependence are in accordance with the correlation-type model of motion detection. Neurobiotin injection suggests extensive coupling among ipsilateral HS cells and additional coupling to tangential cells that have their dendrites in the contralateral hemisphere of the brain. This connectivity scheme accounts for the complex layout of their receptive fields and explains their sensitivity both to ipsilateral and to contralateral motion. Thus the main response properties of Drosophila HS cells are strikingly similar to the responses of their counterparts in the blowfly Calliphora, although we found substantial differences with respect to their dendritic structure and connectivity. This long-awaited functional characterization of HS cells in Drosophila provides the basis for the future dissection of optomotor behavior and the underlying neural circuitry by combining genetics, physiology, and behavior.
运动视觉对于在环境中导航至关重要。由于其遗传易感性，果蝇已经长期作为研究大视野水平运动诱发的光流行为的模式生物。然而，迄今为止，控制这种行为的神经元尚未在果蝇中进行研究。在这里，我们报告了在果蝇的小脑中首次对三个水平系统（HSN、HSE 和 HSS）细胞进行全细胞记录。这三个 HS 细胞以方向选择性的方式对大视野水平运动进行调谐；它们对同侧视野中的从前向后运动兴奋，对从后向前运动抑制。HS 细胞的反应特性，如对比度和速度依赖性，与运动检测的相关模型一致。神经生物素注射表明同侧 HS 细胞之间存在广泛的耦合，并且与位于大脑对侧半球的切线细胞之间存在额外的耦合。这种连接方案解释了它们对同侧和对侧运动的敏感性，说明了它们复杂的感受野布局。因此，果蝇 HS 细胞的主要反应特性与它们在丽蝇中的对应物的反应非常相似，尽管我们发现它们在树突结构和连接方面存在显著差异。这种对果蝇 HS 细胞的功能特征的长期期待的描述为通过结合遗传学、生理学和行为来解析光流行为和基础神经回路提供了基础。
