Environmental enrichment influences the relationship between lateralization and neophobia in zebrafish larvae

Neophobia, the aversion to novelty, is a conserved survival trait that influences individuals' decision-making. In many species, juveniles showed less avoidance of novelty than adults, likely due to their limited experience and their need to gather environmental information. A challenging question is how environmental factors shape sensory processing and behavioural responses. Due to the rapid development of their nervous system and high sensitivity to environmental conditions, zebrafish (Danio rerio) represent a valuable model for investigating the phenotypic plasticity of neophobia. Previous studies showed that two-week-old larvae are more inclined to explore novel stimuli, while older larvae exhibit neophobic responses, indicating an age-dependent shift in exploratory behaviour. Lateralization, i.e. the specialization of the left and right side of the brain to attend different sensory information, may modulate the neophobic response. Here, we investigated how environmental experience alters the relationship between neophobia response and asymmetrical visual inspection in zebrafish larvae throughout early development. After hatching, larvae were reared in either enriched or barren environments. Neophobic response was assessed at 7, 14, and 21 days post-fertilization (dpf) using a novel object test. Results showed that 21dpf larvae raised in enriched environments approached the novel stimulus more quickly and frequently than barren larvae. Enrichment also significantly influenced lateralization, with enriched larvae displaying stronger lateralization. Notably, in enriched larvae, individuals that inspected the novel object more frequently showed weaker and less consistent lateralization. Results suggest that early environmental enrichment affects not only neophobic behaviour, but also the development of lateralized cognitive processing.