Anticipatory 50-kHz Precontact Ultrasonic Vocalizations and Sexual Motivation: Characteristic Pattern of Ultrasound Subtypes in an Individual Analyzed Profile.

Wiktor Bogacki-Rychlik,Michal Bialy,Mateusz Rolf

doi:10.3389/fnbeh.2021.722456

Wiktor Bogacki-Rychlik, Michal Bialy + Show 1 more

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https://doi.org/10.3389/fnbeh.2021.722456

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Abstract

We verified the hypothesis of the existence of forms of individual-specific differences in the emission of anticipatory precontact vocalization (PVs) indicating individualization related to sexual experience and motivation in male rats. Long-Evans males were individually placed in a chamber and 50-kHz ultrasounds were recorded during 5-min periods. In experiment 1, PVs were recorded before the introduction of a female in four consecutive sessions during the acquisition of sexual experience. In experiment 2, PVs were analyzed in three groups of sexually experienced males: with the highest, moderate, and the lowest sexual motivation based on previous copulatory activity. In both experiments, the total number of ultrasounds, as well as 14 different specific subtypes, was measured. The ultrasound profiles for each male were created by analyzing the proportions of specific dominant subtypes of so-called 50-kHz calls. We decided that the dominant ultrasounds were those that represented more than 10% of the total recorded signals in a particular session. The number of PVs was positively correlated with the acquisition of sexual experience and previous copulatory efficiency (measured as the number of sessions with ejaculation). Furthermore, PVs showed domination of the frequency modulated signals (complex and composite) as well as flat and short with upward ramp ultrasounds with some individual differences, regardless of the level of sexual motivation. The results show a characteristic pattern of PVs and confirm the hypothesis that the number of PVs is a parameter reflecting the level of sexual motivation.

Highlights

Ultrasonic vocalization is one of the most intensively studied components of social behavior in rodents
The rats emit 50-kHz ultrasonic vocalization (USV) during different elements of behavior related to their high arousal states (Bell, 1974; Berz et al, 2021) such as: socio-sexual interactions including copulation (Barfield et al, 1979; Bialy et al, 2000; Burgdorf et al, 2008), fighting (Sales, 1972; Burke et al, 2017), playing (Reinhold et al, 2019), and even tickling by the experimenter (Burgdorf et al, 2005; Panksepp, 2005)
Pharmacologically induced high levels of general arousal [related to movement activity and sensory sensitization associated with increased level of wakefulness during activation of the gigantocellular reticular nucleus and associated structures (Pfaff, 2017)] result in the expression of 50-kHz vocalizations with a strong positive correlation between the number of 50-kHz ultrasounds emitted and the level of activation of the dopaminergic and noradrenergic pathways (Brudzynski, 2007, 2015; Wright et al, 2012; Simola, 2015; Hamed et al, 2016; Simola and Costa, 2018; Kuchniak et al, 2019)

Summary

Introduction

Ultrasonic vocalization is one of the most intensively studied components of social behavior in rodents. In the frustration state (situation of the absence of expected appetitive reinforcement), these calls can Anticipatory Ultrasonic Vocalization and Sexual Motivation be frequency modulated (20–35 kHz) with the preceding element at a frequency of about 45-kHz (Geyer et al, 1978; Bialy et al, 2019b). The rats emit 50-kHz USV during different elements of behavior related to their high arousal states (Bell, 1974; Berz et al, 2021) such as: socio-sexual interactions including copulation (Barfield et al, 1979; Bialy et al, 2000; Burgdorf et al, 2008), fighting (Sales, 1972; Burke et al, 2017), playing (Reinhold et al, 2019), and even tickling by the experimenter (Burgdorf et al, 2005; Panksepp, 2005). Pharmacologically induced high levels of general arousal [related to movement activity and sensory sensitization associated with increased level of wakefulness during activation of the gigantocellular reticular nucleus and associated structures (Pfaff, 2017)] result in the expression of 50-kHz vocalizations with a strong positive correlation between the number of 50-kHz ultrasounds emitted and the level of activation of the dopaminergic and noradrenergic pathways (Brudzynski, 2007, 2015; Wright et al, 2012; Simola, 2015; Hamed et al, 2016; Simola and Costa, 2018; Kuchniak et al, 2019)

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