Female C57BL/6 and BALB/c mice differently use the acoustic features of male ultrasonic vocalizations for social preferences

Abstract

Male mice emit ultrasonic vocalizations (USVs) in response to the presence of female mice and their urine. Male USVs attract females, enhancing female reproductive functions, and are thus considered as the courtship song. Previous studies have shown that female mice exhibit disassortative social preferences for male USVs. However, it remains unclear what acoustic features female mice use for the development of these preferences. To address this, we examined social preferences of female C57BL/6 and BALB/c mice using the three-chamber preference test using recorded male USVs. To dissociate the peak frequencies of these USVs from their syllable structure, we digitally manipulated the peak frequencies accordingly. We found that female mice preferred USVs that were dissimilar to those of their own strain. We also observed that, while female C57BL/6 mice were sensitive to changes in the syllable structure and the peak frequency, female BALB/c mice were sensitive to differences in the syllable structure. Our results demonstrate that female C57BL/6 and BALB/c mice differently use the acoustic features such as the peak frequency and the syllable structure for exhibiting disassortative social preferences.

Keywords: BALB/c mice; C57BL/6 mice; behavior; social preference; ultrasonic vocalization.

Fig. 1.

Spectrograms for four types of male USVs. Spectrograms of 2-s fragments of four types of male USVs are shown (the horizontal axis indicates time, the vertical axis indicates frequency, darkness represents amplitude). The upper row shows C57BL/6 USVs and the lower row shows BALB/c USVs. The left column shows the original USVs and the right column shows the modified USVs.

Fig. 2.

Schematic illustration of the behavioral apparatus.

Fig. 3.

USV-associated social preferences of female C57BL/6 mice. Vertical axes indicate number of entries to speaker zones (A, C, E, G) and song searching time (B, D, F, H). Mice were given the choice between B6-60 and B6-74 (A, B), BC-60 and BC-74 (C, D), B6-74 and BC-74 (E, F), and B6-60 and BC-74 (G, H). Boxed labels in horizontal axes indicate the original USVs.

Fig. 4.

USV-associated social preferences of female BALB/c mice. Vertical axes indicate number of entries to speaker zones (A, C, E, G) and song searching time (B, D, F, H). Mice were given the choice between B6-60 and B6-74 (A, B), BC-60 and BC-74 (C, D), B6-74 and BC-74 (E, F), and B6-60 and BC-74 (G, H). Boxed labels in horizontal axes indicate the original USVs.