Neophobia and motivation in birds: A gene expression study informed by reinforcement sensitivity theory

Neophobia, fear of new stimuli, exhibits stable individual variation and has been suggested to have genetic underpinnings linked to specific neural pathways. In this study, we explored the relationship between neophobic responses and gene expression in Japanese quails (Coturnix japonica) within the context of Reinforcement Sensitivity Theory, which delineates the neural mechanisms governing approach and avoidance behaviors. Using a novel object task, we demonstrated that individual differences in approach motivation toward food rewards were significantly associated with the expression of the dopamine receptor gene drd4 in the basal ganglia. Additionally, elevated expression of the serotonin receptor gene htr2a in the nidopallium caudolaterale correlated with increased neophobic behavior. These findings underscore the role of dopaminergic signaling in reward-seeking motivation and serotonergic modulation in avoidance and anxiety responses. Thus, our findings provide initial evidence for specific neurogenetic mechanisms underlying individual variation in neophobia and motivated behaviors in birds, offering new insights into the molecular basis of avian personality. Given the exploratory nature of this study, these findings were not corrected for multiple comparisons and should be considered preliminary, requiring validation in targeted confirmatory studies.