Breslav D, Wojcik M, Koch U, and Becker T (2026), eLife 15

Abstract:
The discovery of a diverse repertoire of ultrasonic vocalizations (USVs) sparked interest inunderstanding their role in mouse social behavior. Social communication in mice is not just vocal,but multimodal and occurs mostly in close proximity. Aiming to unravel the impact direct physicalinteraction has on the vocal communication of same-sex mouse dyads, we separated mice througha divider preventing direct physical interaction, but allowing visual, olfactory and some tactileinteraction through holes. Separated dyads emitted a distinct call repertoire consisting mainly ofcalls in or just above the human audible range (but not squeaks) as well as Noisy calls, and only toa lesser degree of USVs. Increasing the possibility for direct interaction through larger holes in thedivider led to an adaption of the call repertoire. The separation-induced call repertoire wasneither affected by sex, nor was it mouse strain specific, even though differences in spectro-temporal parameters and call class proportion occurred. Lastly, buspirone treatment showed noobservable effect, suggesting anxiety to not be the main driver underlying the separation-inducedcall repertoire. We show that separated same-sex mouse dyads predominantly emit a callrepertoire that until now has only been observed in isolation or during aversive stimulation.