Ultrasonic Vocalizations and Memory Dynamics

Many vertebrates use species-specific vocalizations to communicate information regarding identity, social status or mood, likely future behavior, environmental conditions, and to facilitate social interactions and spatial perception. It is intriguing to consider whether the emission of different types of information could reflect cognitive processing. However, little is known about the role of vocalizations in the dynamics of memory. Long-Evans rats have long been used as an animal model for studying spatial memory in laboratory mazes. They are social animals, and vocal communication is a regular feature of their social interactions and emotional states. They can emit audible sounds, but they mainly communicate in the ultrasonic frequency range. However, few studies have characterized rat ultrasonic vocalizations (USVs) in individual rats performing a behavioral task. One study reported USVs between 30 and 80 kHz associated with rat speed (Laplagne D. A. and Costa M. E., 2016), while another group found 50-kHz calls during spontaneous spatial exploration (Costa G. et al., 2021). Therefore, we began characterizing USVs in an X-maze while the rat learns and memorize the location of a reward. Preliminary results show an increase in the number and diversity of calls during spatial learning, particularly after reward consumption. We believe that this study could contribute to the field of neuroscience by introducing vocalizations as a potential form of memory externalization.