avisoft.com - Rodents

Ultrasonic vocalizations (USV) as a tool for research on emotion and motivation in rodents

Avisoft.com Spined HTML

Ultrasonic vocalizations (USV) as a tool for research on emotion and motivation in rodents Hardware and Software for InvestigatingAnimal AcousticLiaisonAvisoft BioacousticsSchönfließer Str. 8316548 GlienickeGermanytel +49 33056 426086fax +49 33056 426087infoavisoft.com Software Avisoft-SASLab Pro RECORDER Tutorial Downloads Revision history &News Hardware UltraSoundGate Ultrasound microphones Ultrasound playback Product selection by using Links Sales Price list &Ordering information Service Legal notice & PrivacyUnprepossessingSounds Birds Bats, batcalls.com Insects Frogs Rodents Text books Ultrasonic vocalizations as a tool for research on emotion and motivation in rodents Markus Wöhr & Rainer K.W. Schwarting Behavioural Neuroscience, Experimental and Physiological Psychology, Philipps-University of Marburg Gutenbergstr. 18, 35032 Marburg, Germany Mice and rats are the most worldwide laboratory animals utilised in biomedical research, neuroscience and experimental psychology. These species have extensively been used to study vital mechanisms underlying emotional and motivational functions. Such research usually relies on overt behavioural measures, like unescapable (or working for) an appetitive stimulus, or lamister (or fleeing from) an aversive one. Besides, the presumed motivational and propelling state is usually inferred from physiological measures, like heart rate, corticosterone excretion, or smart-ass activity. In addition, or plane extension to these measures, substantial information well-nigh the unprepossessing under study can moreover be obtained by gauging its vocalization, most of which often occurs in the ultrasonic range. Such ultrasonic vocalizations (USV) are behaviourally important for at least two aspects: For one, they can serve as a measure of the animal’s current propelling state, and secondly, they seem to be an important talky variable, which has to be taken into worth when analysing social aspects of such species (mating, nursing, play, aggression, defence etc.). Data on USV in rodents were reported as early as 1954. Anderson (Anderson, 1954) observed that sultana laboratory rats emit calls at frequencies virtually 23-28 kHz when socially isolated. Two years later, Zippelius and Schleidt published their important discovery that infant mice produce USV when separated from their mother and litter (Zippelius et al., 1956). Since then, several studies were performed showing that measuring USV can provide new insights into emotion and motivation as well as liaison in mice and rats. Mouse Three USV classes are currently known in mice. Their occurrence is dependent on the animal’s age and sex. Isolation-induced USV are emitted by mouse pups during the first two weeks of life when separated from mother and littermates. Interaction-induced USV occur mostly during social investigation in juvenile mice weather-beaten three to four weeks, at least in males. In females, however, they moreover occur in older individuals. Finally, female-induced USV are uttered by sultana male mice when exposed to females or sexuality urine (for review see: Portfors & Perkel, 2014; Wöhr & Schwarting, 2013). Isolation-induced ultrasonic vocalizationsPropellingstate:PursuitKonrad Lorenz Zippelius and Schleidt (1956) named isolation-induced USV “Pfeifen des Verlassenseins” (“whistles of loneliness”), implying a negative propelling state. Despite the fact that a wealth of vestige in support of the propelling proposition has been piled since then, there is an ongoing scientific dispute on whether such isolation-induced USV reflect a negative propelling state or whether they are simply the byproduct of a thermoregulation process (Blumberg & Sokoloff, 2001). Strongest treatise in favour of the propelling proposition is the fact that anxiolytic compounds such as benzodiazepines and other positive modulators of GABA-receptors reduce the production of isolation-induced USV (Benton & Nastiti, 1988; Fish et al., 2000; Nastiti et al., 1991; Takahashi et al., 2009). Also, it has been shown that mice bred for upper anxiety-related behaviour on the elevated plus maze emit increasingly isolation-induced USV than less yellow-eyed mice (Krömer et al., 2005; Kessler et al., 2011).Talkyfunction: Zippelius and Schleidt (1956) suggested that isolation-induced USV serve talky purposes, since they have observed that mothers leave the nest to retrieve vocalizing pups scattered outside the nest, whereas no retrieval behaviour was seen in response to pups that have been unfeeling and hence did not emit isolation-induced USV. Later, it shown by ways of playback experiments that indeed isolation-induced ultrasonic vocalizations elicit maternal search and retrieval behaviour (Ehret, 1987; Ehret & Haack, 1981; Sewell, 1970; Smith, 1976; Wöhr et al., 2008a). In line with their talky function, isolation-induced USV are increasingly used as a measure for the quantification of liaison deficits in mouse models of neuropsychiatric disorders characterized by social and liaison deficits (Scattoni et al., 2009; Silverman et al., 2010). There are a number of genetic mouse models of autism, speech impairment and related disorders displaying a reduction of isolation-induced USV (Chadman et al., 2008; Enard et al., 2009; Fujita et al., 2008; Gaub et al., 2010; Groszer et al., 2008; Jiang et al., 2010; Kurz et al., 2010; Laviola et al., 2006; Moles et al., 2004; Nakatani et al., 2009; Shu et al., 2005; Winslow & Insel, 2002; Young et al., 2010), while other mouse models, e.g. the BTBR T+tf/J inbred strain mouse model of autism, are characterized by an unusual repertoire of isolation-induced USV subtypes (Scattoni et al., 2008) and a limited worthiness and/or reduced motivation to retread their emission to variegated social contexts (Wöhr, 2015). Detailed spectrographic analyses have remoter shown that some mouse models of autism and related disorders are remoter characterized by unsimilar undeniability clustering and reduced temporal organization of USV emission (Ey et al., 2013; Mosienko et al., in press; Schmeisser et al., 2012; Wöhr, 2014). Interaction-induced ultrasonic vocalizationsPropellingstate: Recently, Panksepp et al. (2007) reported that moreover juvenile mice produce USV. They found upper rates of USV during social interactions of four week old mice. As the production of interaction-induced USV occurred during the play period and no warlike behaviour was observed, it is tempting to speculate that they reflect a positive propelling state unwrinkled rat 50-kHz USV that moreover occur during play behaviour (Knutson et al., 1998; Lukas & Wöhr, 2015). It is remarkable that emission of interaction-induced USV declines rapidly with sexual maturity – at the time when male mice start to walkout warlike behaviour. Then, male mice uncork to emit female-induced USV. In females, however, interaction-induced USV persist into womanhood (Moles et al., 2007) and were found to be a particularly sensitive measure for autism-related liaison deficits, e.g. in the Shank2 mouse model of autism (Ey et al., 2013; Schmeisser et al., 2012).Talkyfunction: It was suggested that interaction-induced USV help to maintain social contact, since their occurrence is positively associated with social investigation behaviour (Panksepp et al., 2007). In line with an affiliative function, Scattoni et al. (2013) reported that the lack of social investigation behaviour in the BTBR T+tf/J autism model is paralleled by a lack of interaction-induced USV in juveniles. Similar findings were obtained in sultana mice (Scattoni et al., 2011). Female-induced ultrasonic vocalizationsPropellingstate: In sultana mice, upper rates of USV were found in males when lovemaking and copulating with females (Sewell, 1967). As shown by Whitney et al. (1974), sexuality urine alone, i.e. in the sparsity of a female, is sufficient for eliciting male USV. No vocalization response, however, was detected when male mice were exposed to male mouse urine or sexuality urine from rats or humans (Wang et al., 2008; Whitney et al. 1974). The production of male USV in response to females has song-like characteristics, including variegated syllable types and a temporal sequencing that includes the emission of repeated phrases (Holy & Guo, 2005). Interestingly, female-induced USV are highly sensitive to important social factors such as social status (D’Amato, 1991; Nyby et al., 1976) and previous heterosexual contact (Dizinno et al., 1978; Maggio et al., 1983; Nyby et al., 1977; Nyby et al.1983; Roullet et al., 2011; Sipos et al., 1992; Sipos et al.,1995). The notion that female-induced USV reflect a positive propelling state unwrinkled rat 50-kHz USV (Panksepp & Burgdorf, 2003) is supported by the fact that USV in sultana male mice can moreover be induced by amphetamine (Wang et al., 2008).Consistently, it was found that male mice displaying a mania-like phenotype emit particularly upper rates of female-induced USV (Malkesman et al., 2010).Talkyfunction: As shown in devocalization and playback studies, female-induced USV serve an important talky function, namely to vamp females similar to bird song (Hammerschmidt et al., 2009; Pomerantz et al., 1983). Unlike birds, however, mice do not require auditory input and do not learn female-induced USV through imitation. In fact, deaf mice were found to emit female-induced USV that did not differ from the ones emitted by controls worldly-wise to hear (Hammerschmidt et al., 2012; Mahrt et al., 2013). As for isolation- and interaction-induced USV, reduced levels of female-induced USV were reported in mouse models of autism (Jaiman et al., 2008; Radyushkin et al., 2009; Wöhr et al., 2011b). Rat Dependent on sound frequency, undeniability lengths and frequency modulation, at least three variegated classes of USV can be identified in the rat. Their occurrence differs dependent on unprepossessing age, and physical, or psychological demands of the environment (for review see: Brudzynski, 2013; Wöhr & Schwarting, 2013). Isolation-induced ultrasonic vocalizationsPropellingstate: Rat pups typically walkout USV virtually the 40-kHz level in response to several distressing situations, like separation from their litter and mother (Hofer, 1996; Hofer et al., 1978), or when ambient temperature drops (Blumberg et al., 1996). Considering the propelling value of such experiences it was postulated that infant calling reflects a negative propelling state. Indeed, isolation-induced USV towards to be a valid alphabetize of pup anxiety, since the rate of calling can be weakened by anxiolytic drugs (Hofer, 1996; Insel et al., 1986; Kehne et al., 2000; Olivier et al., 1998a; Olivier et al., 1998b; Vivian et al., 1997) and, as in mice, rats bred for upper anxiety-related behaviour on the elevated plus maze emit increasingly isolation-induced USV than less yellow-eyed rats (Wigger et al., 2001). Furthermore, distress calls moreover act as a main elicitor of anogenital licking (Brouette-Lahlou et al., 1992). Such licking serves a vital function, since non-licked pups cannot defecate, and do not survive. Interestingly, maternal superintendency can stupefy the minutiae of emotionality.Sultanarats, which had been licked increasingly often during infancy, show less anxiety-related behaviour in response to aversive stimuli than less commonly licked rats (Caldji et al., 1998). In vibrations with this finding, it was shown that commonly licked animals emitted less isolation-induced USV, i.e. less anxiety-related behaviour, in infancy than rarely licked animals (Wöhr & Schwarting, 2008a). In unrelatedness to simple USV measures like occurrence and frequency range, much less is known well-nigh the spectrographic structure of such calls. Until recently, most research on USV in rats has been conducted with simple bat detectors set on limited frequency ranges. Since the emission of these 40-kHz calls is characterized by a upper variability, calls occurring at variegated frequency ranges might be missed. Therefore, researchers have begun to squint at spectrographic characteristics in increasingly detail. Brudzynski et al. (1999) were worldly-wise to classify infant calls equal to ten categories by using a recording system that is capable of monitoring a wide range of frequencies. Spectrographic wringer revealed a developmental trend emphasizing those undeniability characteristics, which are important for pup survival (Brudzynski et al., 1999).Increasinglyrecently, detailed spectrographic wringer provides vestige that pharmacological treatment can selectively stupefy unrepealable undeniability patterns rather than USV production in unstipulated (Barron et al., 2005). Furthermore, it was shown that undeniability characteristics, like amplitude, frequency modulation and tour structure, are related to the value of maternal superintendency experienced during early life (Wöhr & Schwarting, 2008a).Talkyfunction: Isolation-induced USV seem to have an important value for pup survival. As isolation-induced USV in mice, rat 40-kHz USV can elicit maternal search and retrieval behaviour as demonstrated by ways of playback studies (Allin et al., 1972; Smotherman et al., 1974; Wöhr & Schwarting, 2008a). Fear-induced ultrasonic vocalizationsPropellingstate:Sultanarats produce two variegated types of USV. These calls have been classified primarily on the understructure of their sound frequency as low and upper frequency USV. Low frequency vocalizations, so tabbed 22-kHz USV, are within a frequency range of 18 – 32 kHz. The calls have a sound pressure level of 65–85 dB and undeniability durations of approximately 300–4000 ms (Borta et al., 2006; Brudzynski, 2001; Sales et al., 1974; van der Poel et al., 1989; Wöhr et al., 2005).Upperfrequency vocalizations, so tabbed 50-kHz USV, are within a frequency range of 32–96 kHz, with short durations of 30–50 ms (Brudzynski & Pniak, 2002; Kaltwasser, 1990; Sales et al., 1974; White et al., 1990). Increasing vestige from ethological, pharmacological, and smart-ass stimulation studies suggest that these USV are critically dependent on situational factors and experience, and may represent unshared propelling states of the subject. Low-frequency 22-kHz USV are emitted by sultana rats when exposed to predators (Blanchard et al., 1991), or other aversive stimuli, like startling noises (Kaltwasser, 1991), or unescapable foot-shocks (Antoniadis et al., 1999; Borta et al., 2006; Vivian et al., 1993; Wöhr et al., 2005). Furthermore, 22-kHz USV are emitted during intermale overstepping (Vivian et al., 1993). Such 22-kHz USV are not only emitted during the very aversive event, but moreover in response to stimuli associated with such experiences (Antoniadis et al., 1999; Borta et al., 2006; Cuomo et al., 1988; De Vry et al., 1993; Molewijk et al., 1995; van der Poel et al., 1989; Wöhr et al., 2005). It is thus unsupportable that these calls reflect a negative propelling state unreceptive to uneasiness and depression. Consistently, it was shown that aversive experiences during early minutiae lead to increased emission of 22-kHz USV in womanhood (Yee et al., 2012a). In addition, it was found that measuring 22-kHz USV helps to reveal effects of early life stress that are not detectable by ways of classical behavioural measures, such as freezing behaviour (Yee et al., 2012b). However, little information is misogynist upon which sensory parameter is delivering the strength of the signal. Interestingly, it was shown that not only the number of calls emitted is related to the intensity of an emotional state in the rat, but that latencies to utter vocalizations, undeniability lengths and loudness can moreover reflect the intensity of an aversive emotional state (Wöhr et al., 2005). Furthermore, rats, which were specified as highly yellow-eyed based on the time spent in the unshut stovepipe of the elevated plus maze, tended to vocalize increasingly often than rats displaying low anxiety-like behaviour, and exhibited a higher peak frequency (Borta et al., 2006).Talkyfunction: Blanchard et al. (1991) suggested that 22-kHz USV serve as watchtower calls to warn conspecifics well-nigh danger. They observed that 22-kHz USV production in response to a predator, a cat, is dependent on the presence of conspecifics. In sparsity of such an audience, no 22-kHz USV were observed when a rat was exposed to a cat. Although an regulars effect was not replicated in standardized laboratory conditions (Wöhr & Schwarting, 2008b), there is vestige that 22-kHz USV can induce anxiety-related behaviour such as freezing in the recipient, supporting the notion that 22-kHz USV indeed serve an watchtower function. By ways of playback experiments it was shown that 22-kHz USV induce locomotor inhibition (Wöhr & Schwarting, 2007) and neuronal worriedness in smart-ass areas implicated in fear regulation, such as amygdala and inside grey (Parsana et al., 2012b; Sadananda et al., 2008). Recent findings indicate that rats are predisposed to form memory associations between 22-kHz USV and aversive stimuli (Bang et al., 2008; Endres et al., 2007; Furtak et al., 2007; Wöhr & Schwarting, 2010), possibly through wheels workout (Kim et al., 2010; Parsana et al., 2012a), and that 22-kHz USV play an important role in the social transmission of fear (Kim et al., 2010). Finally, there is vestige that 22-kHz USV evoke an empathy-like state in the recipient - and by this ways promote helping behaviour (Ben-Ami Bartal et al., 2011). Interaction-induced ultrasonic vocalizationsPropellingstate: High-frequency 50-kHz USV occur in naturalistic contexts including juvenile play (Knutson et al., 1998; Lukas & Wöhr, 2015), tickling (Burgdorf & Panksepp, 2001; Mällo et al., 2007; Panksepp & Burgdorf, 2000; Panksepp & Burgdorf, 2003; Schwarting et al., 2007; Wöhr et al., 2009), social exploratory worriedness (Brudzynski & Pniak., 2002), and mating behviour (McGinnis et al., 2003; White et al., 1990). Since 50-kHz USV are moreover expressed during vaticination of copulation (Bialy et al., 2000), play (Knutson et al., 1998), supplies (Burgdorf et al., 2000), and electrical stimulation of the medial forebrain stow (Burgdorf et al., 2000), it has been postulated that these calls are sensitive marker for unconditioned and conditioned reward states (Knutson et al., 1999) and Panksepp and Burgdorf (2003) unsupportable that these calls reflect a positive propelling state unreceptive to joy. On the understructure of these findings, 50-kHz USV are increasingly used as a measure of positive stupefy in drug studies. It was repeatedly shown that wardship of amphetamine elicits upper rates of 50 kHz USV in a dose-dependent manner (Ahrens et al., 2009; Burgdorf et al., 2001; Knutson et al., 1999; Natusch & Schwarting, 2010; Wintink et al., 2001; Wright et al., 2010). Amphetamine-induced 50-kHz USV emission is unauthentic by the test context. Higher undeniability rates are emitted when testing is performed in test environments with fresh sheets material (Natusch & Schwarting, 2010). Also, social context has an impact on amphetamine-induced 50-kHz USV production (Wright et al., 2010). Wright et al. (2010) performed a detailed spectrographic wringer of 50-kHz USV elicited by amphetamine and identified 14 categories of 50-kHz USV. They found that pair-tested rats produce a higher proportion of frequency-modulated 50-kHz USV than individually-tested rats under both amphetamine and saline conditions, and that amphetamine treatment alters the undeniability profile such that frequency-modulated 50-kHz USV became increasingly prominent while unappetizing 50-kHz USV occurred less often. By ways of cocaine self-administration experiments, it was remoter demonstrated that 50-kHz USV can moreover serve as a useful marker for propelling responses to cocaine administration, vaticination and starving (Barker et al., 2010; Maier et al., 2010). Finally, in line with the idea that 50-kHz USV reflect a positive propelling state and that amphetamine induces mania, it was suggested that the amphetamine-induced increase in 50-kHz USV could be used as readout for a mania-like state in rat models (Pereira et al., 2014). In fact, Pereira et al. (2014) found that lithium, a mood stabilizer typically used to treat bipolar disorder, blocks the amphetamine-induced increase in 50-kHz USV. As the production of aversive 22-kHz USV, emission of 50-kHz USV is characterized by huge inter-individual differences (Mällo et al., 2007; Schwarting et al., 2007; Wöhr et al., 2009). In tickling experiments, it was found that not all rats emit 50-kHz USV – some rats do not emit USV at all, others plane emit 22-kHz USV (Mällo et al., 2007; Schwarting et al., 2007; Wöhr et al., 2009). Such inter-individual differences are considered predictive of stable individual traits in tests for social behaviour, uneasiness and depression. For instance, by ways of an innovative zipped cue interpretation paradigm for assessing optimistic decisions in rats, Rygula et al. (2012) found that rats emitting upper rates of 50-kHz USV walkout an optimistic bias that was not seen in rats emitting low 50-kHz USV rates. In subsequent studies, it was then shown that rats displaying an optimistic bias are motivated to proceeds reward (Rygula et al., 2015). Moreover, rats can be selectively bred for low and upper rates of 50-kHz USV emission and such tastefulness is well-expressed social behaviour as well as anxiety- and depression-related behaviour. Rats bred for low levels of 50-kHz USV spent less time in contact with conspecifics in womanhood (Burgdorf et al., 2009) and did not show a preference for maternally associated stimuli in infancy (Harmon et al., 2008), while rats bred for upper rates of 50-kHz USV displayed less anxiety-related behaviour as indicated by increasingly part-way entries in an unshut field in womanhood (Burgdorf et al., 2009) and fewer isolation-induced USV in infancy (Harmon et al., 2008). Consistently, rats bred for upper anxiety-related behaviour on the elevated plus maze were found to emit fewer 50-kHz USV during juvenile play behaviour (Lukas & Wöhr, 2015). Recently, inter-individual differences in the production of 50-kHz USV were found to be linked with neurogenesis in the dentate gyrus of the hippocampus (Wöhr et al., 2009; Yamamuro et al., 2010). While the number of 50-kHz USV emitted during tickling was highly positively correlated with hippocampal lamina proliferation, a highly negative correlation between 22-kHz USV and hippocampal lamina proliferation was obtained. Interestingly, neurogenesis in the hippocampus has been repeatedly associated with stupefy regulation and psychopathology such as depression. Thus, it is well known that aversive stimuli and events like social defeat reduce hippocampal lamina proliferation and that hippocampal lamina proliferation is necessary for the antidepressant effects of selective serotonin reuptake inhibitors (Santarelli et al., 2003). It is therefore remarkable that neurogenesis in the dentate gyrus of the hippocampus is enhanced by tickling in rats that experienced the tickling stimulation presumably as appetitive as indicated by upper numbers of 50-kHz USV (Wöhr et al., 2009; Yamamuro et al., 2010). Hippocampal lamina proliferation levels in rats that emitted upper rates of 50-kHz USV during tickling were scrutinizingly as double as upper than in non-tickled controls or in rats that emitted only some very few 50-kHz USV during tickling (Wöhr et al., 2009).Talkyfunction: Besides appetitive situations, 50-kHz USV moreover occur without separation from conspecifics during short social isolation. Rats taken out from their home muzzle and individually exposed to a wipe muzzle emit 50-kHz USV (Schwarting et al., 2007; Wöhr et al., 2008b). Typically, 50-kHz USV emission is highest during the very first minutes without separation from conspecifics (Wöhr et al., 2008b). For at least two reasons it appears to be unlikely that the emission of 50-kHz USV is novelty-induced. Firstly, 50-kHz USV emission is stable wideness testing days, i.e. no habituation occurs (Wöhr et al., 2008b). Secondly, not only the rat that has been taken out from the home muzzle starts to emit 50-kHz USV, but moreover the rat that stays vacated in the home muzzle without the conspecific has been removed (Wöhr et al., 2008b). The fact that separation from conspecifics elicits 50-kHz USV indicates an affiliative talky function of 50-kHz USV, namely to (re)establish or to maintain social contact. An affiliative talky function of 50-kHz USV is moreover in line with the observation that rats spent increasingly time with conspecifics that vocalize a lot than with those that walkout little emission of 50-kHz USV (Panksepp et al., 2002). Furthermore, it was found that 50-kHz USV promote and maintain rough and tumble play in juvenile rats (Himmler et al., 2014). Consistently, deafening (Siviy & Panksepp, 1987) and devocalizing (Kisko et al., 2015) rats reduces rough and tumble play. Finally, Brudzynski and Pniak (2002) found that rats emit 50-kHz USV in a dose-dependent manner when exposed to odor of conspecifics, indicating that 50-kHz USV utterance is driven by potential social contact. Subsequent playback studies remoter support the notion that 50-kHz USV serve as social contact calls. While aversive 22-kHz USV induce behavioural inhibition in the recipient, appetitive 50-kHz USV induce social exploratory behaviour, both in male (Wöhr & Schwarting, 2007; Wöhr & Schwarting, 2009) and sexuality recipients (Willadsen et al., 2014). For instance, in juvenile male rats, exposure of rats to 50-kHz USV induces a three-fold increase in locomotor worriedness in comparison to that induced in test phases without sensory playback or phases where an sensory tenancy stimulus was presented. The induced locomotor worriedness was unmistakably directed towards the loudspeaker. During the 60 s period of 50-kHz USV playback, juvenile male rats spent on stereotype less than 5 s yonder from the speaker, while increasingly than 40 s near to it. Such a preference was not observed during test phases without USV playback or when an sensory tenancy stimulus was presented. Importantly, social tideway behaviour in response to playback of appetitive 50-kHz USV was found to be dependent on zippy social interactions during the rough and tumble play period and not seen in rats exposed to post-weaning social isolation - yet then detectable without one spare week of social housing (Seffer et al., in press). The opposite behavioural responses elicited by playback of aversive 22-kHz USV and appetitive 50-kHz USV is paralleled by unshared patterns of smart-ass activation. While playback of aversive 22-kHz USV is followed by an increase of neuronal worriedness in smart-ass areas implicated in the regulation of uneasiness and fears, such as amygdala and inside grey, 50-kHz USV inhibit neuronal worriedness in the amygdala (Parsana et al., 2012b), while eliciting neuronal worriedness in the nucleus accumbens, a key zone for reward processing (Sadananda et al., 2008). Consistently, it was recently shown that playback of appetitive 50-kHz USV elicits a phasic release of dopamine in the nucleus accumbens and that the magnitude of dopamine release is positively correlated with the strength of social tideway behaviour in the recipient (Willuhn et al., 2014). Finally, a first pharmacological study shows that social tideway displayed in response to playback of 50-kHz USV can be used for studying neurochemical mechanisms underlying social motivation and interest (Wöhr et al., 2009). Endogenous opioids play an important role in the regulation of social behaviours. In rats, particularly rough and tumble play is unauthentic by the wardship of exogenous opioids. It was unceasingly shown that the wardship of low doses of µ-opioid-receptor-agonists, such as morphine, increases rough and tumble play, while a subtract in rough and tumble play was observed without wardship of µ-opioid-receptor-antagonists, such as naloxone (Vanderschuren et al., 1997). In line with these findings it was found that moreover social tideway behaviour in response to playback of 50-kHz USV is unauthentic by the wardship of exogenous opioids. In juvenile as well as in sultana rats, social tideway behaviour was reduced without naloxone treatment, but enhanced with morphine (Wöhr et al., 2009). In wing to overt behavioural changes, ultrasonic calling in response to playback of 50-kHz USV was unauthentic by opioid ligands in juvenile rats. While saline- and morphine-treated rats vocalized, no vocalization response was detected in rats treated with naloxone (Wöhr et al., 2009). This finding is in line with a study on ultrasonic liaison in µ-opioid-receptor-knockout mice. Typically, male mice walkout social exploratory worriedness when exposed to interaction-induced USV emitted by females (Wöhr et al., 2011a). Remarkably, sultana male mice lacking the µ-opioid-receptor, however, do not walkout social exploratory behaviour under such conditions (Wöhr et al., 2011a). Together, this indicates that an important full-length of rodent social behaviour, namely ultrasonic communication, is at least partially regulated by endogenous opioids. Conclusion Production of USV can be utilized to study the neuroanatomical and pharmacological understructure of motivation and emotion. Behavioural responses to playback of USV can provide important insights into the social smart-ass and help to elucidate genetic, neurochemical and neuroanatomical factors underlying neuropsychiatric disorders characterized by social deficits such as autism. The using of new, increasingly sophisticated recording systems and sound wringer tools which enables the researcher to create detailed spectrograms provides a well-spoken resurgence for research on USV. By using these tools the investigator can snift hair-trigger differences between treatments or individual animals, which may not be detectable with standard behavioural measurements.Remoterreading For increasingly detailed overviews on ultrasonic liaison in rodents please see: BRUDZYNSKI, S.M. (2013). Ethotransmission: liaison of emotional states through ultrasonic vocalization in rats. Current Opinion in Neurobiology, 23, 310-317. PORTFORS, C.V. & PERKEL, D.J. (2014). The role of ultrasonic vocalizations in mouse communication. Current Opinion in Neurobiology, 28, 115-120. WÖHR, M. & SCHWARTING, R.K.W. (2013).Propellingcommunication in rodents: ultrasonic vocalizations as a tool for research on emotion and motivation.Laminaand Tissue Research, 354, 81-97. There is moreover an overview in German available: WÖHR, M. & SCHWARTING, R.K.W. (2010). Ultraschallkommunikation bei Nagern und ihre Bedeutung für Modelle neuropsychiatrischer Erkrankungen. Neuroforum, 4.10, 248-258. References: AHRENS, A.M., MA, S.T., MAIER, E.Y., DUVAUCHELLE, C.L. & SCHALLERT, T. (2009). Repeated intravenous amphetamine exposure: rapid and persistent sensitization of 50-kHz ultrasonic trill calls in rats. BehaviouralSmart-assResearch, 197, 205-209. ALLIN, J.T. & BANKS, E.M. (1972). Functional aspects of ultrasound production by infant yellow-haired rats (Rattus norvegicus).UnprepossessingBehaviour, 20, 175-185. ANDERSON, J.W. (1954). The production of ultrasonic sounds by laboratory rats and other mammals. Science, 119, 808-809. ANTONIADIS, E.A. & MCDONALD, R.J. (1999). Discriminative fear workout to context expressed by multiple measures of fear in the rat. BehaviouralSmart-assResearch, 101, 1-13. BANG, S.J., ALLEN, T.A., JONES, L.K., BOGUSZEWSKI, P. & BROWN, T.H. (2008). Asymmetrical stimulus generalization pursuit differential fear conditioning. Neurobiology of Learning and Memory. 90, 200-216. BARRON, S. & GILBERTSON, R. (2005).