Distinct developmental trajectories of pup ultrasonic vocalizations across ASD mouse models without increased variability.

Autism spectrum disorder (ASD) is characterized by impairments in social communication. Pup ultrasonic vocalizations (USVs), a widely used measure of early social communication in mouse models, have yielded inconsistent findings across studies, hindering cross-model comparisons. Here, we systematically compared isolation-induced pup USVs across three ASD mouse models with distinct etiologies: valproic acid (VPA)-treated, Caps2-/-, and Chd8+/- mice. Alterations in call rate were most pronounced at postnatal day 9, corresponding to the developmental peak of USV production, but both the direction and magnitude of these changes differed across models. VPA-treated and Caps2-/- mice exhibited shortened call duration and simplified frequency structure, whereas Chd8+/- mice showed minimal acoustic alterations. Notably, despite clear differences in mean USV features, within-group variability in call rate and acoustic properties was comparable across all models, including controls. These findings indicate that ASD-related alterations in pup USVs reflect model-specific shifts in developmental trajectories rather than increased inter-individual variability.