Can Rat Ultrasonic Vocalizations Communicate Information On Food?

International audience

anglais. Rats share information through vocalizations. Rat ultrasonic vocalizations (USVs) convey information e.g., on danger (alarm calls emitted at a frequency around 22 kHz) and sex (calls during post-ejaculatory intervals in males, also around 22 kHz). Calls around 50 kHz are associated with positive experiences such as play and tickling and… sex. To date, we don’t know if rats use vocalizations to communicate about food, its nutritional quality, and whether this may influence their own and others' food choices. In the present experiment, we searched for such information, and we recorded rats USVs before and during a meal. Male Wistar rats (n=16) were fasted overnight. We recorded the USVs they emitted for 10 minutes before (anticipation) and for 10 minutes during a meal (feeding), and we video recorded rats’ behaviour at the same time. Calls were classified according to their frequency, duration and profile. Behaviours were also classified using ethograms (e.g., exploration, sniffing, grooming, feeding). Rats emitted USVs before and during feeding. Difference between anticipation and feeding was not in the total amount of USVs emitted, but in the in the subtypes of USVs produced. Feeding was characterized by more “flat USVs” around 40 kHz. Our results reinforce the observation that rats talk while eating. We provide more accurate correlation between behaviour and USVs production. We expect that our results inform us on rat feeding behaviour. Future directions are: comparison of rats ‘talk while they eat different foods, comparison of their speech on food when they eat alone vs. in groups, and improvements of data recording and analysis. Although we are far from having provided a clear demonstration, we propose that, by emitting USVs, rats communicate with others about the nutritional quality of food sources. This share of information could play a role in influencing the feeding choices and behaviours of other rats within their social group. Studying these vocalizations offers a unique opportunity to examine the social dynamics and social influence related to nutritional preferences and needs, drawing intriguing parallels to the study of social influence in human eating behaviour.