A neural circuit for olfactory motion detection

Movement is a defining feature of dynamic environments and a key variable encoded by sensory systems. In vision, neural mechanisms that extract motion direction have been studied extensively across species, revealing circuits that compare signals across space and time. Odor plumes likewise carry motion information in their spatiotemporal structure, which walking fruit flies detect and exploit to improve navigation (Brudner et al., 2025; Kadakia et al., 2022), independent of wind sensing. However, how olfactory circuits compute odor motion remains unknown. Here we identify circuitry in the Drosophila antennal lobe that transforms bilateral odor inputs into direction-selective signals that are propagated to higher brain regions. These direction-selective signals were widespread across most measured olfactory channels, spanning pheromones, food odors, and aversive cues. Directional responses were elicited by odor traces with naturalistic temporal statistics and tuned to inter-antennal delays of {approx}40 ms. Connectomic, physiological, and behav-ioral analyses identified one GABAergic inhibitory neuron in the antennal lobe as a key mediator of direction selectivity. Measurements of dynamics in direction-selective neurons revealed ipsilateral excitation and delayed contralateral inhibition. In a minimal data-driven model, this mechanism was sufficient to generate the observed direction-selective responses. These results establish motion detection as a circuit-level olfactory computation and reveal how an early sensory circuit transforms spatiotemporal chemical signals into a neural representation of odor motion to guide navigation.