| It is well accepted that stressful life events can affect the acquisition of new information. However, less is known about the structures necessary for the modulation of learning by stress. Previously we have shown that exposure to an acute stressor affects the acquisition of eyeblink conditioning in male and female rats. In males, stressor exposure enhances subsequent conditioning whereas in females, stressor exposure impairs conditioning. The present experiments were designed to identify brain regions necessary for the modulation of eyeblink conditioning by stressful experience. The first area examined was the hippocampus, which has been associated with stress and learning. In both male and female rats, hippocampal lesions prevented the stress effect on conditioning. This suggests that positive and negative effects of stress on learning can be mediated by the hippocampus. The goal of the second and third experiments was to determine whether structures that have previously been shown to be critical for the stress effect on conditioning in males, namely the basolateral amygdala (BLA) and the bed nucleus of the stria terminalis (BNST), are also necessary in females. We found that, as in males, the BLA is critically involved during stressor exposure for the stress effect on conditioning in females. However, unlike in males, the BNST is not necessary after stressor exposure during training for the stress-induced impairment of conditioning in females. The possibility that sexual dimorphia within the BNST contributes to difference is discussed. Additionally, the potential interaction of these structures with stress hormones, the eyeblink circuitry, and each other is described. |
