fmr1 Mutation Alters the Early Development of Sensory Coding and Hunting and Social Behaviors in Larval Zebrafish

Autism spectrum disorders (ASDs) are developmental in origin; however, little is known about how they affect the early de-velopment of behavior and sensory coding. The most common inherited form of autism is Fragile X syndrome (FXS), caused by a mutation in FMR1. Mutation of fmr1 in zebrafish causes anxiety-like behavior, hyperactivity, and hypersensitivity in au-ditory and visual processing. Here, we show that zebrafish fmr1-/- mutant larvae of either sex also display changes in hunt-ing behavior, tectal coding, and social interaction. During hunting, they were less successful at catching prey and displayed altered behavioral sequences. In the tectum, representations of prey-like stimuli were more diffuse and had higher dimension-ality. In a social behavioral assay, they spent more time observing a conspecific but responded more slowly to social cues. However, when given a choice of rearing environment fmr1-/- larvae preferred one with reduced visual stimulation, and rearing them in this environment reduced genotype-specific effects on tectal excitability. Together, these results shed new light on how fmr1-/- changes the early development of neural systems and behavior in a vertebrate.