Repeated social defeat stress induces avoidance behavior in susceptible mice. (a) Repeated social defeat stress results in a spectrum of avoidance behavior, divided between susceptible and resilient phenotypes as a function of their social interaction (SI) ratio score. This is the ratio of time a mouse spends in the interaction zone in the presence of a target CD-1 compared with the absence of a target CD-1. (b,c) Susceptible mice spend significantly more time in the corner zone than in the interaction zone, whereas resilient mice spend comparable amounts of time in the interaction zone to control mice that have never undergone a defeat procedure. Both control and resilient mice spend significantly more time in the interaction zone when a target is present. (d,e) Social avoidance behavior can also be expressed as a social interaction ratio. In this panel, the same data are shown in both manners, for comparison. Error bars represent means ± s.e.m. *P < 0.05, multivariate ANOVA/ANOVA. All data shown were collected while conforming to governmental and institutional guidelines for care and use of laboratory animals.