Spontaneous social communication in laboratory mice - placing ultrasonic vocalizations in their behavioral context

In their natural habitat, mice interact and communicate to regulate major functions, such as reproduction, group coordination, and protection. Nevertheless, little is currently known about their spontaneous emission of ultrasonic vocalizations (USVs), despite their broad use as a phenotypic marker in mouse models of neuropsychiatric disorders. Here, we investigated mouse spontaneous communication by coupling automatic recording, segmentation, and analysis of USVs to the tracking of complex behaviors. We continuously recorded undisturbed same-sex pairs of C57BL/6J males and females at 5 weeks and 3 and 7 months of age over three days. Males emitted only a few short USVs, mainly when isolated from their conspecific, whereas females emitted a high number of USVs, especially when engaged in intense dynamic social interactions. The context-specific use of call types and acoustic variations emerged with increasing age. The emission of USVs also reflected a high level of excitement in social interactions. Finally, mice lacking Shank3, a synaptic protein associated with autism, displayed atypical USV usage and acoustic structure, which did not appear in classical protocols, highlighting the importance of studying spontaneous communication. The methods are freely available for the research community (https://usv.pasteur.cloud).