Mouse and rat ultrasonic vocalizations in neuroscience and neuropharmacology: State of the art and future applications

Mice and rats emit ultrasonic vocalizations (USVs), which may express their arousal and emotional states, to communicate with each other. There is continued scientific effort to better understand the functions of USVs as a central element of the rodent behavioral repertoire. However, studying USVs is not only important because of their ethological relevance, but also because they are widely applied as a behavioral readout in various fields of biomedical research. In mice and rats, a large number of experimental models of brain disorders exist and studying the emission of USVs in these models can provide valuable information about the health status of the animals and the effectiveness of possible interventions, both environmental and pharmacological. This review (i) provides an updated overview of the contexts in which ultrasonic calling behaviour of mice and rats has particularly high translational value, and (ii) gives some examples of novel approaches and tools used for the analysis of USVs in mice and rats, combining qualitative and quantitative methods. The relevance of age and sex differences as well as the importance of longitudinal evaluations of calling and non‐calling behaviour is also discussed. Finally, the importance of assessing the communicative impact of USVs in the receiver, that is, through playback studies, is highlighted. Ultrasonic vocalizations (USVs) are emitted by both mice and rats and represent a valuable tool for studying various brain diseases, including neurodevelopmental and psychiatric disorders. USVs can be analysed in both males and females, in pups, juvenile and adult animals. It is important to evaluate not only USV emission but also the animal's response to USV playback. In this review we have provided an updated overview of the value of the study of USVs in the field of neurosciences and neuropharmacology.