Hemoglobin phase of oxygenation and deoxygenation in adults: an fNIRS study

Abstract

Functional Near-Infrared Spectroscopy (fNIRS)is a neuroimaging technique to measure cortical hemodynamics related to functional activation. fNIRS was used to obtain time-averaged phase differences between spontaneous low-frequency oscillatory changes in oxygenated hemoglobin(oxy-Hb)and deoxygenated hemoglobin(deoxy-Hb). This phase difference was referred to as hemoglobin phase of oxygenation and deoxygenation(hPod). Recent study(Watanabe et.al, 2017)in infants demonstrated that hPod is sensitive to the development of the cortex in different behavioral states and stimulus. However, hPod in adults during resting and active state are still uncertain. Therefore, this study aims to validate dynamic changes of hPod in frontal and occipital cortex of adults during resting-state, presence of visual stimuli and verbal WM task by using NIRS. Results showed that hPod during resting-state were (3.57,3.12[rad]), visual stimuli (3.96,3.37[rad]) and verbal WM task (3.69,3.29[rad]) in frontal and occipital cortex, respectively. This study suggests that hPod in adults are in stable antiphase pattern in both resting and active state.