Alteration of Brain Functional Network and Cortisol Level During Induction and Release of Stress: An EEG Study in Young Male Adults

Acute stress in a long period of time could drastically influence one's behavioral and cognitive performances. Therefore, it is important to control the stressful situation and release it after a stressful event. In this regard, understanding of brain mechanism of the stress release will help to introduce new practical approaches. In this study, we hypothesized that induction and release of stress will change the brain functional connectivity pattern. Therefore, by recruiting 20 healthy-subjects and exposing them to stressful events using the trier social stress paradigm, we aimed to investigate patterns of these changes. In a session consist of 23 minutes of psychological stress induction and 20 minutes of recovery, subjects' stress was scored by visual analogue scale (VAS). In addition, salivary cortisol level and EEG data of the subjects were also recorded. Subsequently, brain functional connectivity (FC) maps were calculated in a frequency-specific manner. Then, the effects of inducing and release of stress on the changes of VAS, cortisol level, and FC maps were assessed. Our results revealed that inter-hemispheric FCs of the right frontal regions with other regions of the brain decrease; while it increases at the left frontal regions during inducing of mental stress. Interestingly, the release of stress presented a recovery pattern of inter-hemispheric FCs and meaningful FC changes significantly correlate with changes in the cortisol level. our findings highlight important roles of bihemispheric associations in adaptation and coping with stressful conditions.