Biomarker of Lateralization Index for Stress Calculated from Hemodynamic Responses of fNIRS for Subdividing between Eustress and Distress

We develop a potential biomarker to subdivide the stress groups into eustress and distress groups using hemodynamic responses offunctional near-infrared spectroscopy (fNIRS).We stimulate two stress groups divided by saliva alpha-amylase (sAA) with an international affective picture system (IAPS) inducing positive or negative emotions and measure hemodynamic responses at the same time. As a result, we have developed a newlydesignedbiomarker using fNIRS. To the best of our knowledge, for the first time in the field of brain imaging, it is possible to distinguish differences in brain activation between the three groups (control vs. eustress vs. distress groups).