Fig 2. Analysis of USV categories of C57BL/6N, DBA/2 and FVB/N pups.

(A) Representative sonograms of different calls categories with time in milliseconds (ms) represented on the X-axis and frequency in kHz on the Y-axis. (B_1-10) Percentages of different call categories emitted by each strain at P4, P8 and P12 during separation (trial 1) and reunion with a littermate (trial 2); 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, ***p< 0.001).