Fig. 1

Acute traumatic stress increases anxious behaviors and fear responses. a A schematic of the behavioral test. Restraint and tail shock stresses are used as the traumatic stressor. 7 days later, anxiety levels are examined with an EPM test. Fear conditioning, fear generalization, fear extinction, and fear recall after memory extinction are then assessed sequentially. b Freezing responses of unstressed control (n = 26) and stressed (n = 79) mice during fear conditioning (two-way repeated measures ANOVA). c-d Fear generalization test. c Stressed mice show significantly enhanced freezing responses to a novel cue (left) and a CS (right) compared with those of unstressed control mice. d Generalization indices, calculated as the ratios of freezing responses to the novel cue and to the CS, are significantly higher in stressed mice than in control mice. **P < 0.01 (unpaired t test). e Freezing responses during extinction training are comparable between the two groups (two way repeated measures ANOVA). f Stressed mice show significantly increased freezing after extinction training. ****P < 0.0001 (unpaired t test). g EPM data from stressed and unstressed control mice. Stressed mice spend significantly less time in the open arms than control mice (left). Stressed mice make significantly fewer entries into open arms than controls (middle). Travel distances significantly differ between two groups (right). *P < 0.05; ns, not significant (unpaired t tests). Plots show means ± SEMs