Acute stress induces coordinated reorganization across interacting brain networks

Stress initiates alterations in electrophysiological brain activity that are correlated with increases in muscle sympathetic nerve activity (MSNA), heart rate (HR) and blood pressure (BP). However, we do not know if changes in brain activity occur solely in regions comprising the central autonomic network, or if other large-scale brain networks are involved in the stress-induced pressor response. To answer this question, this study measured connectivity between different brain regions at rest and during acute stress, using magnetoencephalography in 29 healthy individuals. Whole head and regions of interest analyses were performed using phase-lag indices as a connectivity metric. Regions of interest were confined to the central autonomic, sensorimotor, salience, default and central executive networks. Functional connectivity was calculated on magnetoencephalography recordings that were filtered into delta (1-4Hz), theta (4-8Hz), alpha (8-13Hz), beta (13-30Hz), low gamma (30-80Hz) and high gamma (80-120Hz) bands. Substantial reductions in connectivity were observed during cognitive stress. These were largely characterized by reduced parahippocampal-sensorimotor connectivity in beta and high gamma bands. Moreover, reduced connectivity within the central autonomic, sensorimotor, and default mode networks was noted, specifically as a reduction in the alpha band between the precuneus and hippocampus. We observed a salience directed switching between the default and executive networks, driven by reduced right anterior cingulate-right insula connectivity. Furthermore, we observed reduced right medial prefrontal cortex-brainstem connectivity in beta band. Our results indicate that stress influences the functional connectivity of several key brain regions that interact with multiple large-scale brain networks linked to mental and physical states.