RESUMEN
It is generally thought that the effect of acute stress on higher-order functions such as working memory is, for an important part, mediated by central catecholamine activity. However, little is known about the association between neuroendocrine stress responses and catecholamine-dependent working memory-related brain function in the absence of stress. Here, we investigate for the first time in healthy humans (n = 18) how neuroendocrine responses to stress (cortisol and alpha-amylase) relate to fronto-parietal working memory activity changes in response to atomoxetine, a noradrenaline transporter inhibitor that selectively increases extracellular cortical dopamine and noradrenaline. We observed positive correlations between stress-induced cortisol (Pearson's r = 0.75, P < 0.001) and alpha amylase (r = 0.69, P = 0.02) increases and catecholamine-dependent working memory-related activity in dorsolateral prefrontal cortex. Stress-induced cortisol increases furthermore correlated with supramarginal gyrus working memory-related activity (r = 0.79, P < 0.001). Comparing high vs low stress responders revealed that these correlations were driven by decreased working memory activity on placebo and greater working memory activity increases following atomoxetine in high stress responders. These results further corroborate the notion that neuroendocrine responses to stress are an informative proxy of catecholamine function relevant to higher order functions and provide novel hints on the complex relationship between acute stress, catecholamine function and working memory.