Figure 2.

Results of Experiment 1 (5 sessions of extinction). (A) During the footshock stress session, freezing behavior increased as a function of the 4 shock presentations. (B) During extinction training, freezing declined in Group Stress-Ext but modestly increased in Group NoStress-Ext. (C) Prior footshock stress suppressed open field exploration. This effect was completely reversed by extinction training. (D) Freezing behavior during the test session in the stress context (Context A). Extinction training reduced freezing behavior in stressed mice to the levels of mice that did not receive footshock stress. (E) Prior footshock stress potentiated unconditioned fear of a novel tone. This effect of stress was not attenuated by extinction training. (F) Prior footshock stress increased freezing during contextual fear conditioning in a novel context (Context C). There was no significant effect of extinction training. (G) In the Context C test session, context-elicited fear was enhanced in mice that received prior footshock stress. This effect was not reduced by extinction training. NoStress-NoExt (n=18); NoStress-Ext (n=17); Stress-NoExt (n=18); Stress-Ext (n=17). *p<0.05, **p<0.01, ***p<0.001