Association between Novel Object Recognition/Spontaneous Alternation Behavior and Emission of Ultrasonic Vocalizations in Rats: Possible Relevance to the Study of Memory

Abstract

Rats emit ultrasonic vocalizations (USVs) in situations with emotional valence, and USVs have also been proposed as a marker for memories conditioned to those situations. This study investigated whether USV emissions can predict and/or be associated with the behavior of rats in tests that evaluate unconditioned memory. To this end, rats were subjected to “tickling”, a procedure of heterospecific play that has emotional valence and elicits the emission of USVs, and afterwards evaluated in the novel object recognition test (NOR) and in the single trial continuous spontaneous alternation behavior (SAB) test in a Y-maze. The number of 22-kHz USVs (aversive) and 50-kHz USVs (appetitive) emitted in response to tickling and during NOR and SAB tests were scored, and the correlations among them and with rats’ behavior evaluated. Rats emitted 50-kHz USVs, but not 22-kHz USVs, during the NOR and SAB tests, and such calling behavior was not linked with the behavioral readouts indicative of memory function in either test. However, rats that prevalently emitted 22-kHz USVs in response to tickling displayed an impaired NOR performance. These findings suggest that measuring the emission of USVs could be of interest in studies of unconditioned memory, at least with regard to 22-kHz USVs.

Mouse and rat ultrasonic vocalizations in neuroscience and neuropharmacology: State of the art and future applications

“…The hypothesis that rat 50‐kHz USVs mark the arousal associated with stimuli that possess positive affective valence and the presence of a positive emotional state is corroborated by the evidence that these USVs are emitted in response to and/or in expectation of stimuli that may be beneficial to an individual and/or its colony. The situations that trigger the emission of 50‐kHz USVs may have social valence, for example, non‐aggressive contacts with either conspecifics or familiar humans (Bialy et al, 2000; Burgdorf & Panksepp, 2001) but may also be devoid of social valence, for example, the administration of drugs with rewarding properties or the performance of behavioral tests that evaluate emotionality or memory (Burgdorf et al, 2001; Costa et al, 2021; Ma et al, 2010; Rao & Sadananda, 2015; Reyes et al, 2021; Simola et al, 2010, 2012). Rats may emit 50‐kHz USVs also in anticipation of appetitive stimuli of various nature, a response that is thought to mark the expectation of positive emotional states (Brudzynski & Pniak, 2002).…”

A Protocol for the Non-invasive Method of Ultrasound Separation During the Sociosexual Vocal-Non-contact Model in Rats

“…Ultrasonic vocalization (USV) emitted by rats has gained considerable acceptance in recent decades as an applicable parameter in neurobehavioral research ( Burgdorf and Panksepp, 2006 ; Taracha et al, 2012 ; Potasiewicz et al, 2019 ; Caruso et al, 2020 ; Costa et al, 2021 ). The frequency spectrum of the main emitted signals ranges from 20 kHz to about 70 kHz.…”