Male mice exhibited greater exploration of the center square when given ketamine after UCS in the open field test. Behavior (24 hours post-injection) was automatically scored in EthoVision and parsed into: A, total distance traveled; B, center square distance; C, center square frequency; D, center square duration. Females were more active than males in all four measures. UCS-exposed males exhibited a significant, or trending, behavioral modulation after ketamine for measures B-D (see Table 1). Abbreviations: no stress saline (No str-sal), no stress ketamine (No str-ket), unpredictable chronic stress saline (UCS-sal), unpredictable chronic stress ketamine (UCS-ket). Error bars: ± standard error of mean (SEM). Three-way ANOVA, main effect of sex: ** p < 0.01, Two-way ANOVA, main effect of drug: * p < 0.05.