Fig. 1.

Effects of stress on trace eyeblink conditioning in young adult and middle-aged male and female rats. The graph depicts the mean (± S.E.M.) percentage of CRs averaged in six blocks (100 trials each) for a total of 600 trials of trace eyeblink conditioning for stressed and unstressed subjects. (A) Adult male rats were exposed to the stressful event and trained 24 h later. They emitted a greater percentage of CRs across the blocks of training trials. (B) In contrast, middle-aged males that were exposed to the same stressor did not express any change in the percentage of conditioned responses. (C) Adult females were exposed to the stressful event and trained 24 h later. As shown, they emitted a smaller percentage of conditioned responses when compared to females that were not exposed to the stressor. (D) Exposure to the stressful event did not alter the percentage of conditioned responses in middle-aged females.