The zebrafish lateral line is a sensory system used to detect changes in water flow. It is comprised of clusters of superficial hair cells called neuromasts. Modulation occurs via excitatory and inhibitory efferent neurons located in the brain. Using mosaic transgenic labelling we provide an anatomical overview of the lateral line projections made by individual inhibitory efferent neurons in 5-day old zebrafish larvae. For each hemisphere we estimate there to be six inhibitory efferent neurons located in two different nuclei. Three distinct cell types were classified based on their projections; to the anterior lateral line around the head, to the posterior lateral line along the body, or to both. Our analyses corroborate previous studies employing back-fills, but our transgenic labelling allowed a more thorough characterisation of their morphology. We found that individual inhibitory efferent cells connect to multiple neuromasts and that a single neuromast is connected by multiple inhibitory efferent cells. The efferent axons project to the sensory ganglia and follow the sensory axon tract along the lateral line. Time-lapse imaging revealed that inhibitory efferent axons do not migrate with the primordium as the primary sensory afferent does, but follow with an 8-14 hour lag. These data bring new insights into the formation of a sensory circuit and support the hypothesis that different classes of inhibitory efferent cells have different functions. Our findings provide a foundation for future studies focussed towards unravelling how and when sensory perception is modulated by different efferent cells.

中文翻译：

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单个投射揭示的特征是通过多个抑制性传入细胞来激活斑马鱼侧向线的神经母细胞

斑马鱼侧线是一种用于检测水流变化的传感系统。它由称为神经质的浅层毛细胞簇组成。调节通过位于大脑中的兴奋性和抑制性传出神经元发生。使用镶嵌转基因标记，我们提供了在5天大的斑马鱼幼虫中单个抑制传出神经元做出的侧线投影的解剖学概述。对于每个半球，我们估计在两个不同的核中有六个抑制性传出神经元。根据其预测对三种不同的细胞类型进行了分类；头部周围的前侧线，身体的后侧线或两者兼有。我们的分析证实了先前使用回填的研究，但是我们的转基因标记允许对其形态进行更全面的表征。我们发现单个抑制性传出细胞连接到多个神经质，并且单个神经母细胞被多个抑制性传出细胞连接。传出的轴突伸向感觉神经节，并沿着侧线跟随感觉轴突道。延时成像显示，抑制传出轴突并不像主要感觉传入一样随原基一起迁移，但会滞后8-14小时。这些数据为感觉回路的形成提供了新的见识，并支持不同类别的抑制性传出细胞具有不同功能的假设。我们的发现为将来的研究奠定了基础，这些研究的重点是弄清不同传出细胞如何以及何时调节感官知觉。