Investigating Decision-Making in Larval Zebrafish (Danio rerio) Through Multi-Sensory Integration in the Startle Response Circuit

When presented with a sudden sensory stimulus, all organisms will perform a startle response. This defensive reflex is a well-conserved behaviour that is studied in many organisms. In zebrafish, Danio rerio, the startle response is a rapid muscle contraction that initiates an escape response. Zebrafish select between two different startle responses given how threatening they perceive the stimulus. Previous studies have used acoustic stimuli to provoke these different startle responses, and investigate how zebrafish select one response over the other. These studies have limited themselves by focusing on single-sensory inputs as they affect decision-making in the startle response circuit. In this study, I investigate the role that the visual system plays in acoustic decision-making. I introduce rearing larval zebrafish in conditions of various light exposures as a method to affect visual system development. Then, through presenting acoustic stimuli to the zebrafish in behavioural assays, I show that fish raised in different lighting conditions have distinct sensitivities to acoustic stimuli, and they show discrepancy in what they consider threatening stimuli. My results suggest that visual input affects acoustic decision-making in larval zebrafish. My study provides further understanding of decision-making in zebrafish through multi-sensory integration at a behavioural and circuit level