Chapter 4.2 - Activation of limbic system structures by replay of ultrasonic vocalization in rats

Abstract

Abstract Since the first observation of ultrasonic vocalizations in rats, several hypotheses have been proposed regarding a possible function of such calls as echolocation, temperature regulation and others. Today, however, it is well-established that ultrasonic vocalizations in rats serve as important social signals. Rat behavioral and neuronal responses to 22 kHz calls indicate that this call type serves as an alarm call. Although 22 kHz calls are not innately recognized as alarm calls, they can reach alarm signal value as a consequence of associative learning, which is facilitated by a biological preparedness to associate 22 kHz calls with aversive events. The perirhinal cortex might be at least part of the “neural template” responsible for such a biological preparedness. On the other hand, behavioral and neuronal responses to 50 kHz calls indicate that this call type serves as a contact call. Social approach displayed in response to 50 kHz calls is paralleled by an activation of frontal cortex and the nucleus accumbens, which might be related to the appetitive value of 50 kHz calls.