Anticipation of play elicits high-frequency ultrasonic vocalizations in young rats.

Abstract

The authors provide initial documentation that juvenile rats emit short, high-frequency ultrasonic vocalizations (high USVs, approximately 55 kHz) during rough-and-tumble play. In an observational study, they further observe that these vocalizations both correlate with and predict appetitive components of the play behavioral repertoire. Additional experiments characterized eliciting conditions for high USVs. Without prior play exposure, rats separated by a screen vocalized less than playing rats, but after only 1 play session, separated rats vocalized more than playing rats. This findings suggested that high USVs were linked to a motivational state rather than specific play behaviors or general activity. Furthermore, individual rats vocalized more in a chamber associated with play than in a habituated control chamber. Finally, congruent and incongruent motivational manipulations modulated vocalization expression. Although play deprivation enhanced high USVs, an arousing but aversive stimulus (bright light) reduced them. Taken together, these findings suggest that high USVs may index an appetitive motivation to play in juvenile rats.

“Laughing” rats and the evolutionary antecedents of human joy?

“…We have observed this in two separate situations. First, in sequential daily play sessions, the amount of chirping that occurs during a session is correlated with the number of dorsal contacts (play solicitations) emitted during play testing [38]. Second, when we bred animals for high chirping, we also found that these animals exhibited significantly more play solicitations than randomly selected and low-chirp lines [63].…”

“…50-kHz chirping is evoked most robustly by the positive social interchange of rough-and-tumble play, and even more so by human tickling Sustained bouts of human laughter are evident in children during tickling and rough-and-tumble play, especially when they are chasing each other [80,90]. A similar type of vocal activity (chirping at about a frequency of 50 kHz, which humans cannot hear without special equipment, of course) is also evident when young rats play [38]. To our knowledge, play and tickling are by far the most robust initiators of the short 50-kHz chirps that are also common at much lower levels in other positive social situation [13].…”

“…This problem was picked up by Brian Knutson in our lab, who first monitored the ultrasonic vocalizations of young rats in the midst of play. He promptly discovered a great abundance of 50-kHz type chirps during this type of social interaction [38]. This type of vocalization had already been studied extensively in the context of sex [1] and a much lower level of this type of vocalization had also been seen in the context aggression (Ref.…”

“…In a series of studies we have shown that 50-kHz calls can be disassociated from locomotor behavior, with increases of 50-kHz calls being associated with a decrease [38] as well as no change [13] in locomotor behavior. As summarized in Fig.…”

Variation in the emission rate of sounds in a captive group of false killer whales Pseudorca crassidens during feedings: possible food anticipatory vocal activity?

“…In fact, it has been found that sound rates, type of calls, and acoustic structure within a call may vary depending on the context of behaviors such as aggression, panic, and social separation (rodents: Goldstein et al, 1996;Albeck et al, 1997;primates: Bayart et al, 1990;Champoux and Suomi, 1994;Friedman et al, 1995;Laudenslager et al, 1995;Boinski et al, 1999;farm animals: von Borell and Ladewig, 1992;Désautés et al, 1997;Weary et al, 1997). Animals living in a controlled environment with predictable daily routines, experience anticipation which is a mental state that can infl uence their behaviors including vocalizations (Krishnamurthy, 1994;Knutson et al, 1998;Burgdorf et al, 2000;Waitt and Buchanan-Smith, 2001;Ulyan et al, 2006;Düpjan et al, 2008;Gilbert-Norton et al, 2009;Polizzi di Sorrentino et al, 2010).…”