The secret to stress adaptation lies in the brain "one hour later"!

[Key Points]

・ World-first discovery through simultaneous fMRI (functional Magnetic Resonance Imaging) and EEG (electroencephalography) measurements that brain activity related to psychological resilience (the mind's ability to adapt to stress) appears most strongly "approximately 60 minutes after" receiving stress, rather than immediately after.

・ Identified that the key to recovery is the silencing of the brain's "alarm" (salience network) and the switch to "introspection mode" (default mode network).

・ By confirming the optimal state and timing for intervention to enhance resilience, more effective stress management is expected in mental health and educational settings.

[Overview]

A research group led by Assistant Professor Noriya Watanabe (currently Associate Professor at the Faculty of Informatics, Shizuoka Institute of Science and Technology) and Professor Masaki Takeda of the Brain Communication Research Center, Research Institute, Kochi University of Technology, has elucidated for the first time in the world the brain mechanism involved when humans exercise psychological resilience (*1), the ability to adapt to stressful environments.

Using an advanced measurement method that simultaneously employs fMRI (functional Magnetic Resonance Imaging) (*2), which has excellent spatial resolution, and EEG (electroencephalography) (*3), which has excellent temporal resolution, the research group recorded detailed brain activity over a long period starting immediately after acute stress. As a result, they discovered that while conventional resilience research has focused primarily on reactions immediately after stress, human-specific resilience appears in the brain after a significant time lag of approximately 60 minutes following stress (see Figure 1).

These research results present a new intervention timing (time window) for mental health care and educational support in a stressful society and were published in the internationally influential multidisciplinary scientific journal PNAS (Proceedings of the National Academy of Sciences).

Figure 1. Temporal changes in brain networks related to psychological resilience. The upper row shows functional network changes via fMRI. Each band on the outer circumference of the circle represents a brain region, and lines indicate regions that are active in synchronization. Approximately 60 minutes later, in individuals with high resilience, activity in the introspection mode network (centered on the posterior cingulate cortex, etc.) reached its peak, while in those with low resilience, strong activity was observed in the network related to the brain's alarm. The lower row shows changes in the intensity of high-beta components (associated with stress and tension) via EEG. Immediately after stress, no significant difference was observed between high and low resilience individuals, but approximately 60 minutes later, high-beta components appeared strongly over a wide area in low-resilience individuals.

[Research Content and Results]

Previous resilience research has focused mainly on animal experiments, evaluating resilience through simple behavioral indicators such as whether "depressive-like behavior" is shown under strong stress. However, human resilience is not merely insensitivity to stress; it involves a complex interplay of advanced psychological processes such as past experiences, self-efficacy, and a positive attitude. This research group has delved into this "human-specific stress adaptation mechanism," which had previously been a black box.

In this study, changes following acute stress induced by cold stimulation were observed for approximately 90 minutes in about 100 participants...