Resting brain activity: differences between genders.

This study investigated electrophysiological (EEG) and hemodynamic (near infrared spectroscopy - NIRS) measures as a function of gender in normal adult individuals. The EEG data analysis was based on the resting eyes closed brain activity of 300 respondents (160 females). The NIRS analyses was based on 155 respondents (88 females). The total power, coherence and approximate entropy measures were calculated for the EEG recordings in the δ, θ, lower-1 α, lower-2 α, upper α, β and γ bands. Based on the filtered NIRS data the concentration, the peak frequency and the Hurst exponent (H) of oxi-Hb and deoxi-Hb were determined. Higher power values in females as compared with males were observed in the β and γ bands. In the lower-1 α, lower-2 α and upper α bands this difference was only pronounced in the parieto-occipital areas. Higher coherences in the δ band in females as compared to males was observed, whereas a reverse pattern of differences was present in the β and γ bands. A similar pattern of differences was also observed for the ApEn measures. Males showed a higher percentage of oxygen saturation of hemoglobin, more irregular and faster spontaneous fluctuations in oxi-Hb and deoxi-Hb as compared with females. It can be concluded that males and females differ in the local as well as long range coding of information - the binding of distributed responses - as well as in the excitability dynamics of their cortical network.