Relationship between fluctuations in the cerebral hemoglobin oxygenation state and neuronal activity under resting conditions in man.

Simultaneous measurements by near-infrared spectroscopy and electroencephalography were performed during 15-min resting periods in nine healthy adult brains. The peak frequencies of the frontal and occipital rhythms varied with the time course like the hemoglobin oxygenation state. Changes in the amount of oxygenated hemoglobin in the frontal region by more than 50% of the maximum resting variation range were accompanied by changes in peak frequency at the electrode position between two optodes. The results suggest that spontaneous neuronal activity is responsible for fluctuations in the hemoglobin oxygenation state in the resting state.