Study on mental stress using near-infrared spectroscopy, electroencephalography, and peripheral arterial tonometry.

In this research, we used near-infrared spectroscopy (NIRS) as an alternative technique for mental state analysis, and compared its performance with other conventional techniques such as electroencephalography (EEG) and peripheral arterial tonometry (PAT) during stress and healing tasks. We measured biological signals simultaneously in our experiments using these techniques for comparison. NIRS results showed that the level of total hemoglobin in the frontal cortex increased during a stress task and decreased during a healing task for all subjects whose blood volume change was properly recorded. EEG, however, showed inconsistent results due to task variation. Only PAT gave consistent results in many of the subjects. Taken together, the results suggest that NIRS might be suitable for mental state evaluation, with PAT as an alternative.