How cognitive performance-induced stress can influence right VLPFC activation: an fMRI study in healthy subjects and in patients with social phobia.

The neural bases of interactions between anxiety and cognitive control are not fully understood. We conducted an fMRI study in healthy participants and in patients with an anxiety disorder (social phobia) to determine the impact of stress on the brain network involved in cognitive control. Participants performed two working memory tasks that differed in their level of performance-induced stress. In both groups, the cognitive tasks activated a frontoparietal network, involved in working memory tasks. A supplementary activation was observed in the right ventrolateral prefrontal cortex (VLPFC) in patients during the more stressful cognitive task. Region of interest analyses showed that activation in the right VLPFC decreased in the more stressful condition as compared to the less stressful one in healthy subjects and remain at a similar level in the two cognitive tasks in patients. This pattern was specific to the right when compared to the left VLPFC activation. Anxiety was positively correlated with right VLPFC activation across groups. Finally, left dorsolateral prefrontal cortex (DLPFC) activation was higher in healthy subjects than in patients in the more stressful task. These findings demonstrate that in healthy subjects, stress induces an increased activation in left DLPFC, a critical region for cognitive control, and a decreased activation in the right VLPFC, an area associated with anxiety. In patients, the differential modulation between these dorsal and ventral PFC regions disappears. This absence of modulation may limit anxious patients' ability to adapt to demanding cognitive control tasks.