A neural circuit basis for bilateral olfactory input-enhanced chemosensory avoidance navigation

Our understanding of how bilaterian animals utilize parallel input channels from paired sensory organs to optimize chemosensory behavior and the underlying neural circuit mechanisms are limited. Here we developed microfluidics-based behavioral and brainwide imaging platforms to study the neural integration of binasal inputs and chemosensory avoidance in larval zebrafish. We show that larval zebrafish efficiently escape from cadaverine-carrying streams by making more frequent swim bouts and larger undirected turns. Binasal inputs are strictly required for the nasal input-dependent component of klinokinesis, while each nasal input additively enhances angular orthokinesis. Throughout brain regions, including those along the olfactory processing pathways, a distributed neural representation with a wide spectrum of ipsilateral-contralateral nasal stimulus selectivity is maintained. Nonlinear sensory information gain with bilateral signal convergence is especially prominent in neurons weakly encoding unilateral cadaverine stimulus, and associated with stronger activation of sensorimotor neurons in the downstream brain regions. Collectively, these results provide insights into how the vertebrate model sums parallel input signals to guide chemosensory avoidance behavior.