Titre : A sensory-motor hub driving photo-taxis in zebrafish

Résumé : Animals continuously gather sensory cues in order to move towards favorable environments. Efficient goal-directed navigation requires sensory perception and motor command to be intertwined in a feedback loop, yet the neural substrate underlying this sensorimotor task in the vertebrate brain remains elusive. Here we present analysis of whole-brain calcium recordings together with circuit modeling to reveal the neural mechanisms through which zebrafish performs phototaxis, i.e. actively orients towards a light source. Key to this process is a self-oscillating hindbrain network that acts as a pacemaker for ocular saccades and controls the orientation of successive swim-bouts. It further integrates visual stimuli in a state dependent manner, i.e. its response to visual inputs varies with the motor context, a mechanism that manifests itself in the phase-locked entrainment of the circuit by periodic stimuli. A rate model is developed that reproduces our observations and demonstrates how this sensorimotor processing eventually biases the animal trajectory towards bright regions.