Repertoire and Biological Function of Ultrasonic Vocalizations in Adolescent and Adult Rats

Adolescent and adult rats emit ultrasonic vocalizations (USVs) for communication with conspecifics. These USVs can be broadly divided into two subgroups that possess distinct acoustic features and have different behavioral significance: the 22-kHz USVs, emitted in aversive situations, and the 50-kHz USVs, emitted in appetitive situations. These USVs communicate the aversive or appetitive arousal to the conspecifics. USVs in either of the subgroups can influence the emotional state of the recipient rats and guide their behavior accordingly. Therefore, USVs are instrumental in maintaining the social structure and particularly the affiliative and collaborative forms of behavior that are characteristic of the rat species. This chapter provides an overview of the qualitative and quantitative features of the USVs emitted by adolescent and adult rats and of the situations that are associated with the emission of these vocalizations.