Rodent ultrasonic communication: Male prosocial 50-kHz ultrasonic vocalizations elicit social approach behavior in female rats (Rattus norvegicus).

Abstract

Rats emit distinct types of ultrasonic vocalizations (USV), which serve as situation-dependent affective signals with important communicative functions. Low-frequency 22-kHz USV typically occur in aversive situations, such as social defeat, whereas high-frequency 50-kHz USV can be observed in appetitive situations, like rough-and-tumble-play in juveniles or mating in adults. The 2 main USV types serve distinct communicative functions and induce call-specific behavioral responses in the receiver. While 22-kHz USV probably serve as alarm calls, 50-kHz USV appear to serve a prosocial communicative function in the sexual and the nonsexual context. In the sexual context, however, this view has recently been challenged by playback studies where only very limited behavioral changes were observed in response to prosocial 50-kHz USV. The aim of the present study was therefore to test whether female rats display social approach behavior in response to male prosocial 50-kHz USV by means of our established playback paradigm. To this aim, we exposed female rats to playback of the following 2 acoustic stimuli: (a) natural male 50-kHz USV and (b) time- and amplitude-matched white noise, with the latter serving as acoustic control for novelty-induced changes in behavior not linked to the communicative function of male prosocial 50-kHz USV. Our present findings show that female rats display high levels of social approach behavior in response to male prosocial 50-kHz USV, but not time- and amplitude-matched white noise, supporting the conclusion that male prosocial 50-kHz USV are likely to play an important role in establishing social proximity and possibly regulate mating behavior.

Studying Socio‐Affective Communication in Rats through Playback of Ultrasonic Vocalizations

“…Finally, USV emission by the subject rat in response to playback of 50-kHz USVs can be determined (Avisoft Bioacoustics). By this means, it has been consistently shown that 50-kHz USVs lead to social approach behavior in juvenile and adult male rats (Wöhr and Schwarting, 2007, 2009, 2013Brenes et al, 2016;Seffer et al, 2015) as well as in female rats (Willadsen et al, 2014; Fig. 8.35.2), supporting the notion that they serve an affiliative function as social contact calls.…”

Reduction in 50-kHz call-numbers and suppression of tickling-associated positive affective behaviour after lesioning of the lateral hypothalamic parvafox nucleus in rats

“…High-frequency calls are produced by juvenile or adult rats during rough-and-tumble play [41], during mating [41][42][43][44], as an expression of reward during voluntary exercise [45], as well as in response to drugs of abuse [46,47], and it is widely accepted today that they reflect a positive affective state [46,48,49]. Consequently, one of their functions appears to be the communication of emotional states to conspecifics [50].…”

“…Rats emitting high numbers of tickling-induced 50-kHz USVs have been shown to approach the hand of the tickling experimenter with a short latency period [54]. In addition to conveying information appertaining to affective states, 50-kHz USVs are suggested to fulfil important communicative functions and to be involved in the establishment and maintenance of close social contacts [44,[55][56][57][58]. Rats use low-frequency (22-kHz) alarm calls as a warning to conspecifics of imminent dangers, with a view to promoting a survival-enhancing behavioural strategy in the colony as a whole [59][60][61].…”

Rats concatenate 22 kHz and 50 kHz calls into a single utterance

“…Production of 50 kHz calls is associated with mating and other social interactions or the expectation of reward (Burgdorff et al, 2008). Playbacks of 50 kHz calls induce approach behavior in both male and female rats, promoting social contact Willadsen et al, 2014). During the encounter with an unfamiliar estrous female prior to mating, a male's vocalizations can contain call types from both the 22 kHz and 50 kHz call category (e.g.…”

“…Wright et al, 2010;Brudzynski, 2013) that play important roles in their social interactions (e.g. Brudzynski, 2009;Willadsen et al, 2014). The rat model has allowed comprehensive recording of peripheral vocal movements (Riede, 2011).…”