Video 3_Remote control of wildtype zebrafish optomotor response with a photoswitchable drug.mp4

Given the established in vivo effects of this compound, we further investigated its impact on sensorimotor behaviors.</p>Methods<p>We focused on the optomotor response in zebrafish larvae and assessed its potential as a tool for circuit perturbation and behavioral analysis, for the first time combined with photopharmacology. We performed experiments in head-fixed and free-swimming larvae to assess their capacity to detect and follow optic flow, and to characterize swimming speed patterns and tail bout properties following administration of the two Carbadiazocine photoisomers.</p>Results<p>In both paradigms, treatment with the pre-illuminated compound decreased accuracy in responding to optic flow (correct turning percentage dropping from ~95% to ~80% in head-fixed experiments and from ~65% to ~20% in free-swimming experiments).

Speed analysis revealed more frequent and prolonged fast movements, with fewer slow movements, even without visual stimulation. Tail bout analysis showed increased 15–30 Hz bout frequencies, corresponding to irregular tail movements. These effects were absent with the dark-relaxed compound.</p>Discussion<p>Together, these findings provide a foundation to probe neuronal circuits underlying behavior in diverse animal species using a dynamic range of photostimulation patterns.</p>