Stress affects the brain at a network level: the salience network is supposedly upregulated, while at the same time the executive control network is downregulated. While theoretically described, the effects in the aftermath of stress have thus far not been tested empirically. Here, we compared for the first time resting-state functional connectivity in a large sample of healthy volunteers before and after a mild social stressor. Following the theoretical prediction, we focused on connectivity of the salience network (SN), the executive control network (ECN) and the default mode network (DMN). The DMN exhibited increased resting-state functional connectivity following the cyberball task to the key nodes of the SN, namely the dorsal anterior cingulate cortex (dACC) and the anterior insula, as well as sensorimotor regions and higher-order visual areas. We conclude that this increased connectivity of the DMN with key nodes of the SN and regions responsible for preparatory motor activity and visual motion processing indicates a shift towards an ‘alerted default mode’ in the aftermath of stress. This brain response may be triggered or aggravated by (social) stress induced by the cyberball task, enabling individuals to better reorient attention, detect salient external stimuli, and deal with the emotional and affective consequences of stress.

Social stress has a major detrimental impact on subjective well-being. Previous research mainly focused on two methods to induce and measure social stress: social exclusion and performance evaluation. For social exclusion researchers frequently focused on the Cyberball task, which in contrast to many psychosocial stress paradigms does not include a performance component. The aim of the current study was to establish an optimized psychosocial stress paradigm by combining both, social exclusion as well as performance evaluation within a single fMRI paradigm. We implemented a modification of the Cyberball task including a performance game (with exclusion and inclusion periods) in addition to the already established exclusion and inclusion periods. This indeed resulted in increased subjective stress in the performance game. Hence, the modified Cyberball version seems to be superior in mapping relevant neural social stress correlates more pronounced and reliably. Exclusion within the performance-related context contrasted to the unmodified exclusion was associated with higher activation in the dorsal anterior cingulate cortex and the anterior insula. Moreover, the modified exclusion reflected greater social processing in the precuneus, several temporo-parietal and medial prefrontal areas, as suggested by the additional task aspects of social evaluation and social perspective taking. The findings emphasize that public negative evaluation is effective in substantially enlarging and potentiating the distressing effect of exclusion on a subjective as well as on a neural level. This may have a great potential for further experimental research on social stress.

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