(A) A schematic drawing of the experimental setup for USV recording in adolescent mice. USV were recorded for 10 min in the apparatus as a habituation phase (trial 1), followed by a social contact phase for 10 min with a same-sex littermate on the right compartment (trial 2) followed by another trial for 10 min with an adult unfamiliar mouse from another strain (trial 3). The intertrial interval between trials was 15 min. (B-E) USV analysis including number (B), duration (C), frequency (D) and amplitude (E) of calls during the three trials. (F) Percentages of different call categories emitted by each strain during each trial; n = 7 for C57BL/6N (2 males and 5 females), n = 8 for DBA/2 (4 males and 4 females) and n = 11 for FVB/N (6 males and 5 females), all data as mean ± SEM (two-way ANOVA, *p< 0.05, **p< 0.01).