From Internal State to Behavior: A Synchronized Optical System for Multi-Organ Imaging in Zebrafish Larvae

Animals must combine external and internal information to produce adaptive behaviors: the smell of food, for example, does not trigger the same response in a hungry versus a satiated animal. This integration is constant and bidirectional, yet the underlying mechanisms remain poorly understood. Addressing this topic in a holistic manner is challenging because physiological signals arise from different anatomical regions and they express themselves at different temporal scales. In this context, Zebrafish larvae are an ideal model to address it: fast, ex-utero development, a rich behavioral repertoire, optical transparency granting non-invasive access to internal organs and the nervous system, and genetic tools. We designed and built a low-cost, low-complexity, novel optical system that allows simultaneous multi-organ acquisition in the same individual, capturing lateral and ventral views of the whole larva on a single sensor. Combined with a custom analysis pipeline, this allows extraction of cardiac and intestinal activity together with behavioral segmentation. The system is designed for integration with light-sheet calcium imaging across the whole brain, providing an unprecedented platform to study brain-body axes. We will present preliminary results on the temporal relationship between heart and gut rhythms related with the start of an escape behavior, until now considered spontaneous.