The Emotional Meaning and Measurement of Ultrasonic Vocalizations in Laboratory Rats

Abstract: Rats are widely used in experimental research in biology, medicine, and psychology, and many studies need the measurement of rats’ emotional states. Ultrasonic vocalizations (USVs) of rats are means to express and transmit emotions: among them FM-50 kHz USVs are for positive emotions such as pleasure, flat-50 kHz USVs are for social communication, and 22 kHz USVs are for negative emotions such as anxiety and disgust. Collecting and analyzing the USVs of rats provides researchers a possible way to quantify the emotional states of rats during experimental manipulations. This paper discusses the emotional meaning of USVs in rats and provides suggestions for measuring and analyzing USVs in rats.