Prefrontal Cortical Connectivity and Coupling of Infraslow Oscillation in the Resting Human Brain: A Two-Channel Broadband NIRS Study

Abstract The resting-state infra-slow oscillation (ISO) of the cerebral cortex reflects the neurophysiological state of the human brain. ISO results from distinct vasomotion with endogenic (E), neurogenic (N), and myogenic (M) frequency bands. Quantification of prefrontal ISO in cortical haemodynamics and metabolism in the resting human brain may facilitate the identification of objective features characteristic of certain brain disorders. The goal of this study was to explore and quantify the prefrontal ISO of the cortical concentrations of oxygenated hemoglobin (Δ[HbO]) and redox-state cytochrome-c-oxidase (Δ[CCO]) as hemodynamic and metabolic activity metrics in all three E/N/M bands. Two-channel broadband near-infrared spectroscopy (2-bbNIRS) enabled measurements of the forehead of 26 healthy young participants in a resting state once a week for five weeks. After quantifying the ISO spectral amplitude (SA) and coherence at each E/N/M band, several key and statistically reliable metrics were obtained as key features: (1) SA of Δ[HbO] at all E/N/M bands, (2) SA of Δ[CCO] in the M band, (3) bilateral connectivity of hemodynamics and metabolism across the E and N bands, and (4) unilateral hemodynamic-metabolic coupling at both E and M bands. These features have promising potential to be developed as objective biomarkers for clinical applications in the future.