Social Transmission of Avoidance Behavior Under Situational Change in Learned and Unlearned Rats

Abstract

Rats emit distinct types of ultrasonic vocalizations, which differ depending on age, the subject's current state and environmental factors. Since it was shown that 50-kHz calls can serve as indices of the animal's positive subjective state, they have received increasing experimental attention, and have successfully been used to study neurobiological mechanisms of positive affect. However, it is likely that such calls do not only reflect a positive affective state, but that they also serve a communicative purpose. Actually, rats emit the highest rates of 50-kHz calls typically during social interactions, like reproductive behavior, juvenile play and tickling. Furthermore, it was recently shown that rats emit 50-kHz calls after separation from conspecifics. The aim of the present study was to test the communicative value of such 50-kHz calls. In a first experiment, conducted in juvenile rats situated singly on a radial maze apparatus, we showed that 50-kHz calls can induce behavioral activation and approach responses, which were selective to 50-kHz signals, since presentation of 22-kHz calls, considered to be aversive or threat signals, led to behavioral inhibition. In two other experiments, we used either natural 50-kHz calls, which had been previously recorded from other rats, or artificial sine wave stimuli, which were identical to these calls with respect to peak frequency, call length and temporal appearance. These signals were presented to either juvenile (Exp. 2) or adult (Exp. 3) male rats. Our data clearly show that 50-kHz signals can induce approach behavior, an effect, which was more pronounced in juvenile rats and which was not selective to natural calls, especially in adult rats. The recipient rats also emitted some 50-kHz calls in response to call presentation, but this effect was observed only in adult subjects. Together, our data show that 50-kHz calls can serve communicative purposes, namely as a social signal, which increases the likelihood of approach in the recipient conspecific.

Context‐dependent individual differences in playfulness in male rats

“…one with frequencies around 50 kHz (Burgdorf & Panksepp, 2001;Burgdorf et al, 2008;Burgdorf, Panksepp, & Moskal, 2011;Knutson, Burgdorf, & Panksepp, 2002;Webber et al, 2012;Wöhr & Schwarting, 2007). During rough-and-tumble play, rats emit frequency-modulated 50 kHz USVs (Burgdorf et al, 2008;Himmler, Kisko, Euston, Kolb, & Pellis, 2014;Kisko, Himmler, Himmler, Euston, & Pellis, 2015;Kisko, Wöhr, Pellis, & Pellis, 2016;Knutson et al, 1998), which are emitted in situations normally considered positive or of high reward value, such as receiving or anticipating a food reward or having sex (Burgdorf et al, 2008;Burgdorf et al, 2011;Vanderschuren, 2010).…”

Exercise reward induces appetitive 50-kHz calls in rats

“…When analyzing their wheel patterns over days (Fig. 2), we found that low-runners did not increase wheel revolutions (p-values >.05), whereas high-runners showed a running pattern characterized by an increase from day 1 to 5 (p-values <.05), a subsequent plateau (i.e., day [5][6][7][8][9][10][11][12][13][14], and a trend for a decline thereafter. Statistically, high-runners differed from low-runners on days 5-11 and 14 (p-values <.01).…”

“…6,11,12,14,15]. Besides their communicative function [13], 50-kHz calls are thought to indicate reward anticipation, incentive motivation [9], and positive affective states [5,6,11,16]) Several rewarding stimuli have been shown to elicit 50-kHz calls conditionally or unconditionally: rough-and-tumbleplay [16,21], tickling [22,23], mating or sexual contact [24], palatable stimuli (e.g., food) [25], electrical brain stimulation [5], and psychostimulatory drugs like amphetamine and cocaine [7,8,26,27]. Also, 50-kHz calls largely depend on dopamine (DA) and norepinephrine function in the brain, especially within the mesolimbic DA system [5-7,27a,27b].…”

Sexual performance and precontact 50-kHz ultrasonic vocalizations in WAG/Rij rats: Effects of opioid receptor treatment

“…Recently, more data have supported the hypothesis that ultrasonic vocalizations in rats serve a communication function [11][12][13][14][15]. Parallel to the communicational role, ultrasonic vocalizations at the 50-kHz band in rats can be an indicator of a positive emotional state which relates to the dopamine level, mu opioid receptor stimulation in the ventral tegmental area, and self-and drug-stimulation of the rewarding systems [16][17][18][19][20][21].…”