Temporal Dynamics of Courtship Behavior and Vocal Communication in Freely Interacting Mice

• Alyssa Khusid, Neuroscience, University of Delaware

• Joshua Neunuebel, Neuroscience, University of Delaware

Mice emit ultrasonic vocalizations (USVs) during courtship behaviors. Although social behavior in mice has been extensively studied in dyads, it remains unclear how courtship behaviors and USVs emitted during them evolve when multiple animals freely interact with different potential partners. To address this, we analyzed five-hour recordings of freely interacting mixed-sex groups (n = 11 groups; two males and two females each; 13–21 weeks old; B6.CAST-Cdh23Ahl+/Kjn; Sangiamo et al., 2020). Using a supervised machine learning approach (Kabra et al., 2013), we extracted courtship chases, investigations, and approaches. First, we quantified their temporal profiles and compared the bouts during the first and the last 90 minutes of each session. Across all three behaviors, the number of bouts significantly declined from the first to the last 90 minutes of the sessions (paired t-tests, all p < 0.05). Because chase was the most frequent behavior and had the highest vocal rate, we further investigated temporal patterns of male and female vocal communication during chases. We found that the number of USVs for both sexes decreased over time (paired t-tests, both p < 0.05). We then characterized each chase bout into four categories and examined their temporal distributions, also recording their total proportions: male-only vocalizing (15.92 ± 2.95%), female-only vocalizing (1.24 ± 0.40%), both partners vocalizing (38.07 ± 5.50%), and silent (44.78 ± 6.32%). Finally, within the “both” category, we found that males vocalized 3.17 times more frequently than females. Overall, these results reveal that courtship behaviors and vocal communication during these behaviors in freely interacting mice are temporally structured. Future work will further investigate the temporal dynamics of bouts in which both partners vocalize by examining the order of male and female vocalizations within individual chase interactions.