Neonatal vocalization rate predicts future prosocial behavior in C57 BL/6J mice.

Neonatal Ultrasonic vocalizations (USVs) are an innate form of mouse communicative behavior that are produced throughout the first two postnatal weeks. While neonatal USVs are commonly assessed, their relationship to future behaviors is largely unknown. In the present study, we addressed this by analyzing vocalizations in C57BL/6 pups throughout development. We then examined each animal's anxiety, locomotion, depressive, prosocial, and aggressive behaviors in adolescence. To analyze the results, we used correlations and also divided the mice into a high and a low group according to quantitative measures of their vocalizations, using a median split design. For call rate, we found a large positive correlation between call rate and sociability, furthermore, high vocalizers were significantly more prosocial than low vocalizers. No other significant differences and significant correlations were found. When we controlled for the relative contribution of the weight, sex, litter size, and sex composition of the litter, as well as the duration, pitch and amplitude of the calls, we found that high vocalizers were still significantly more prosocial than low vocalizers, indicating that this relationship cannot be attributed to these other factors. When the data was split according to the pitch, duration, and amplitude of the vocalizations, no significant adolescent behavioral differences nor correlations were found. Similarly, the types of calls produced had minimal relevance to adolescent behaviors. Altogether, our study elucidated a long-term implication for USVs, finding that the number of USVs produced throughout early development is a significant predictor of an animal's future prosocial behavior.