Encoding of wind direction by central neurons in Drosophila

Wind is a major navigational cue for insects, but how wind direction is decoded by central neurons in the insect brain is unknown. Here we find that walking flies combine signals from both antennae to orient to wind during olfactory search behavior. Movements of single antennae are ambiguous with respect to wind direction, but the difference between left and right antennal displacements yields a linear code for wind direction in azimuth. Second-order mechanosensory neurons share the ambiguous responses of a single antenna and receive input primarily from the ipsilateral antenna. Finally, we identify novel “wedge projection neurons” that integrate signals across the two antennae and receive input from at least three classes of second-order neurons to produce a more linear representation of wind direction. This study establishes how a feature of the sensory environment—wind direction—is decoded by neurons that compare information across two sensors.

风力是昆虫的重要导航线索，但目前学界尚未明确昆虫大脑中枢神经元如何解码风向信息。本研究发现，在嗅觉搜索行为中，行走果蝇会整合双侧触角的信号以实现风向定向。单根触角的运动无法明确指示风向，但左右触角的位移差可形成方位角（azimuth）风向的线性编码。二阶机械感觉神经元（second-order mechanosensory neurons）仅表现出与单根触角类似的模糊响应，且主要接收同侧触角的输入。最后，我们鉴定出一类新型楔形投射神经元（wedge projection neurons），该类神经元可整合双侧触角的信号，并接收至少三类二阶机械感觉神经元的输入，从而实现风向的更线性表征。本研究阐明了感觉环境的一项特征——风向——是如何通过比对双侧传感器（即触角）信息的神经元完成解码的。