Most prior research examined differences in the EEG frequency bands between eyes-closed and eyesopen conditions at the resting state as a baseline; without counter checking on the mental health state of the subjects; the depressive symptoms were often not assessed or controlled during the experiment. We examined EEGs of euthymic participants (who were free from the psychiaric symptoms) for the above two conditions at the resting state. A population of participants with healthy levels of depression, anxiety, and stress symptoms (n = 50) has been examined with the Patient Health Questionnaire-9 (PHQ-9) and Depression Anxiety Stress Scale-21 (DASS-21). The powers of the alpha rhythm, interpreted as relaxation waves, were higher during eyes-closed compared to eyes-open condition (P = 0.0…) in all brain regions (32 EEG channels). The prefrontal cortex was characterized by higher delta, theta, and beta powers during eyes-open periods at the resting state, as compared with eyes-closed ones.

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