Divergent Visuomotor Strategies in Teleosts: Neural Circuit Mechanisms in Zebrafish andDanionella cerebrum

Abstract

Many animals respond to sensory cues with species-specific coordinated movements to successfully navigate their environment. However, the neural mechanisms that support diverse sensorimotor transformations across species with distinct navigational strategies remain largely unexplored. By comparing related teleost species, zebrafish (Danio rerio, ZF) and Danionella cerebrum (DC), we investigated behavioral patterns and neural architectures during the visually guided optomotor response (OMR). Closed-loop behavioral tracking during visual stimulation revealed that larval ZF employ burst-and-glide locomotion, while larval DC display continuous, smooth swimming punctuated with sharp directional turns. Although DC achieve higher average speeds, they lack the direction-dependent velocity modulation observed in ZF. Whole-brain two-photon calcium imaging and tail tracking in head-fixed fish reveals that both species exhibit direction-selective motion encoding in homologous regions, including the retinorecipient pretectum, with DC exhibiting fewer binocular, direction-selective neurons overall. Kinematic analysis of head-fixed behavior reveals that DC sustain significantly longer directed swim events across all stimuli than ZF, highlighting the divergent visuomotor strategies, with ZF reducing tail movement duration in response to oblique, turn-inducing stimuli. Lateralized motor-associated neural activity in the medial and anterior hindbrain of both species suggests a shared circuit motif, with distinct neural circuits that independently control movement vigor and direction. These findings highlight the diversity in visuomotor strategies among teleost species, underscored by shared sensorimotor neural circuit motifs, and establish a robust framework for unraveling the neural mechanisms driving continuous and discrete visually guided locomotion, paving the way for deeper insights into vertebrate sensorimotor functions.