The analysis of ultrasonic vocalizations
Although rats do make audible sounds, most communication, particularly between rats takes places at a frequency beyond our human hearing. These so-called ultrasonic vocalizations (USVs) in rats range from roughly 22 to 90 kHz. Traditionally, USV research has shown that rat calls in the 20 – 25 kHz range are typically associated with negative affect, while calls in the 40 – 90 kHz range are typically associated with positive affect. Rat pups, when separated from their mothers usually make calls in the 30 – 45 kHz range.
While this subdivision in three bands is still largely correct, recent research focusses more on the classification of individual calls within each of these ranges. We aim to investigate the specific language rats use to communicate their emotional state. For that purpose, we expose rats to different conditions (play behaviour, anticipatory pleasure, social interaction, tickling) and record USV. Using Deepsqueak we categorize these calls into different types to see whether rats use different types of calls under different circumstances. Additionally, we will investigate whether pharmacological and/or genetic manipulations alter the USV characteristics. In the long run, we expect that this will give us a better understanding of the emotional state of rats.