Although the optode arrangement (52 channels) of ETG-4000 can cover the whole PFC, part of temporal cortex and part of motor cortex. In this study, the resting-state brain functional analysis between male and female groups was only focused in PFC region that consist of 34 channels of yellow diamonds in the Fig. 1. Figure 2 shows the flowchart of resting-state fOT data analysis. Here, the gender-specific effects of hemispheric asymmetry of PFC in the resting-state were investigated with time series and spectrum analysis of optical signals at low frequency because the low-frequency band (< 0.1 Hz) were used in the numerous fMRI and fNIRS studies for functional connectivity study in resting-state. In order to obtain the relatively steady signals and reduce the potential effects of unstable signals for further data analysis, the first 2 minutes data was discarded for each participant. This process is employed in previous studies of fNIRS field [21, 23]. The band-passed optical signal analysis avoids the physiological noise of low and high frequency such as respiratory (0.1-0.3 Hz) and cardiac-related fluctuations (0.75-1 Hz) in oxygen supply
