Fig. 1: Acute social defeat results in social avoidance of a novel mouse.

a In the acute social defeat model (aSD) a male subject mouse (C57BL/6 J, 11–25 weeks of age) was placed in the home cage of an adult male CD1 for a five-minute bout of defeat then returned to the home cage. Twenty-four hours later the subject mouse was allowed five-minutes to explore a novel environment containing a littermate of the CD1 aggressor housed within a wire cup. Warm colors represent more time spent. b Heatmap illustrating a non-defeated subject’s preference investigation of the novel CD1 mouse. c Heatmap illustrating a defeated subject’s preference for the “far zone” opposite the location of the CD1. d Defeated mice spent significantly more time in the “far zone” of the arena when compared to non-defeat mice 24 h after aSD (No Defeat: 97.98 ± 3.6 s vs. Defeat: 190.49 ± 25.0 s, N = 6 & 12 mice, respectively, unpaired t-test p = 0.02). e Non-defeated control mice interacted with the CD1 mouse at a significantly higher frequency, measured as discrete entries into the interaction zone, than the defeated mice 24 h after aSD (No Defeat: 91.17 ± 16.1 entries vs. Defeat: 40.25 ± 9.4 entries, N = 6 & 12 mice, respectively, unpaired t-test p = 0.01). f One month following a single bout of defeat the two groups, as a whole, no longer exhibited significantly different measures of avoidance (No Defeat: 127.80 ± 20.6 s vs. Defeat: 180.75 ± 30.5 s, N = 6 & 11 mice, respectively, unpaired t-test p = 0.25). Notably, though, a more avoidant subpopulation ( >200 s spent in the far zone) of defeated mice emerged as distinct from the more investigative mice (Defeat-Avoidant: 265.81 ± 14.2 s vs. Defeat-Investigative: 78.68 ± 6.7 s, N = 6 & 5 mice, respectively, unpaired t-test p < 0.0001). *p < 0.05, **p < 0.01.