Cerebral resting state oscillations study with TD fNIRS

This work aims to show the possibility to perform in- vivo acquisitions with high sampling rate (20 Hz) with Time Domain functional Near-Infrared Spectroscopy (TD fNIRS) for studying brain resting state oscillations. Based on numerical simulations, a protocol was designed for acquiring hemodynamics parameters on 13 healthy volunteers during normal and forced respiration. Both the experiments had a length of 15 minutes and during the forced respiration one, subjects were ask to breath at 5 breaths per minute (0.083 Hz) following a metronome. Systemic (UP) and cortical (DW) oxy- (O(2)Hb) and deoxy- (HHb) hemoglobin concentrations (absolute values) were successfully retrieved with a single measure on the frontal lobe. Temporal series and Power Spectral Density (PSD) were calculated for: physiological signals (electrocardiogram, breath signal, blood volume pulse, skin conductance and temperature), total counts at the two wavelengths (RED = 689.5 +/- 0.5 nm and IR=828.5 +/- 0.5 nm), counts in temporal gates for RED and IR, absolute values of O(2)Hb_UP, O(2)Hb_DW, HHb_UP and HHb_DW. Specific characteristic peaks were evaluated in the cardiac, respiratory, low, and very low frequency bands. The behavior among the subjects was uniform and differences between the two experiments were found.