Acoustic Communication in Rats: Effects of Social Experiences on Ultrasonic Vocalizations as Socio-affective Signals

Abstract

Ultrasonic vocalizations (USV) serve important communicative functions as socio-affective signals in rats. In aversive situations, such as inter-male aggression and predator exposure, 22-kHz USV are emitted. They likely function as appeasement signals during fighting and/or as alarm calls to warn conspecifics. In appetitive situations, 50-kHz USV are uttered, most notably during social interactions, such as rough-and-tumble play and mating. It is believed that they fulfill an affiliative function as social contact calls. Social experiences or their lack, such as social isolation, can have profound impact on the emission of 22- and 50-kHz USV by the sender in later life, albeit direction and strength of observed effects vary, with time point of occurrence and duration being critical determinants. Little, however, is known about how social experiences affect the behavioral responses evoked by 22- and 50-kHz USV in the recipient. By means of our 50-kHz USV radial maze playback paradigm, we recently showed that the behavioral response elicited in the recipient is affected by post-weaning social isolation. Rats exposed to four weeks of isolation during the rough-and-tumble play period did not display social approach behavior toward 50-kHz USV but some signs of social avoidance. We further found that physical environmental enrichment providing minimal opportunities for social interactions has similar detrimental effects. Together, this indicates that social experiences can affect socio-affective communication in rodents, both at the level of sender and recipient. Deficits seen following post-weaning social isolation or physical environmental enrichment might be useful to model aspects of neurodevelopmental disorders characterized by social and communication deficits, such as autism and schizophrenia.

Simultaneous Changes in Sleep, qEEG, Physiology, Behaviour and Neurochemistry in Rats Exposed to Repeated Social Defeat Stress

“…They probably function as appeasement signals during fighting and/or as alarm calls to warn conspecifics. In contrast, rats can emit high- frequency ultrasonic vocalizations (50 kHz), which are generally assumed to reflect the animals' highly positive emotional and motivational state [15,16]. …”

“…USVs in the ‘low' (20-30 kHz) and ‘high' (31-70 kHz) frequencies in rats may communicate affective states that occur in various conditioned aversive situations. Low-frequency USVs (22 kHz) are generally emitted in highly significant context situations such as exposure to predator and inter-male aggression, including social defeat [15,16]. They probably function as appeasement signals during fighting and/or as alarm calls to warn conspecifics.…”

Social dysfunction after pediatric traumatic brain injury: A translational perspective

“…Male rodents in particular also communicate via the emission of ultrasonic vocalizations as auditory signals (Bean et al, 1981). Vocalizations differ in type, pattern and frequency depending upon the social context (Wohr et al, 2015). For example, rats typically emit low frequency (22 kHz) vocalizations in response to aversive stimuli such as an aggressive encounters or exposure to a predator.…”

Social experience during adolescence in female rats increases 50 kHz ultrasonic vocalizations in adulthood, without affecting anxiety‐like behavior

“…Adolescent rats also emit 50 kHz vocalizations during play and such calls can, in turn, facilitate further playful interactions (Burke, Kisko, Euston, & Pellis, ). Consistent with the notion that more adolescent social experiences can enhance social competency, male rats that are group housed during adolescence emit more 50 kHz ultrasonic vocalizations (USVs) in response to female partners and exhibit greater approach behavior to playbacks of 50 kHz USVs when in adulthood compared to adult rats that were single housed in adolescence (Inagaki, Kuwahara, Tsubone, & Mori, ; Seffer et al, ; see Wöhr et al, ). In comparison, relatively little is known about the effects of adolescent social experience on later sexual and social competence, including vocal communication, in female rodents (Burke et al, ).…”

“…These findings are consistent with the hypothesis that lack of appropriate social experience during adolescence impairs later social competence. Vocal communication is an important component of social interactions (Wöhr, Engelhardt, Seffer, Sungur, & Schwarting, ). Male rodents, for example, can emit 50 kHz ultrasonic vocalizations (USVs) in order to solicit social contact and socio‐sexual interactions (Brudzynski, ) and prevent playful interactions from escalating into aggression (Burke, Kisko, Pellis et al, ).…”