Frequency-specific functional connectivity in the brain during resting state revealed by NIRS

Area of Science:

• Neuroscience
• Biomedical Engineering
• Physiology

Background:

• Resting-state functional connectivity, identified via fMRI, shows temporal correlations in brain signals.
• Near-infrared spectroscopy (NIRS) also detects these correlations, but frequency-specific characteristics remain unclear.

Purpose of the Study:

• Investigate the frequency dependency of functional connectivity using multichannel NIRS.
• Examine oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) signal fluctuations across different frequency bands.

Main Methods:

• Analyzed spontaneous hemodynamic fluctuations using multichannel NIRS.
• Decomposed oxy-Hb and deoxy-Hb signals into various frequency bands (0.009-0.1Hz).
• Calculated coherence values to assess functional connectivity between cortical regions.

Main Results:

• Both oxy-Hb and deoxy-Hb showed functional connectivity within local and contralateral regions across a wide frequency range.
• Oxy-Hb signals exhibited frequency-specific functional connectivity between frontal and occipital regions (0.04-0.1Hz).
• Homologous connectivity showed high coherence across a wide frequency range, while fronto-posterior connectivity was specific to a narrow band.

Conclusions:

• NIRS is a powerful tool for studying resting-state cortical network properties.
• Frequency-specific connectivity patterns may reflect different underlying neural synchronization mechanisms.