Interaction of endogenous cortisol and noradrenaline in the human amygdala

Animal studies show that glucocorticoid effects on memory depend on noradrenergic activation within an intact amygdala. Testing this model in humans is the subject of the present fMRI study. Healthy subjects watched emotional and neutral stimuli after having received a betablocker or placebo. Cortisol levels of all subjects were determined and served as a marker of the subject’s (endogenous) cortisol level during the experiment. Viewing emotional pictures resulted in increased amygdala activation compared to neutral pictures and this effect was enhanced in subjects with a high versus low cortisol level under placebo condition. Betablockade with propranolol, lowering the noradrenergic level in the amygdala, disrupted this effect and apparently the interaction with cortisol. These data support the hypothesis that high endogenous cortisol levels at the time of encoding interact with noradrenergic activation in the amygdala in man.