Exploration of cerebral activation using hemodynamic modality separation method in high-density multichannel fNIRS

Area of Science:

• Neuroscience
• Biomedical Engineering
• Physiology

Background:

• Functional near-infrared spectroscopy (fNIRS) measures brain activity via hemodynamic responses.
• fNIRS signals can be contaminated by systemic physiological changes, complicating the interpretation of neural activation.
• Distinguishing cerebral functional signals from systemic physiological noise is crucial for accurate brain imaging.

Purpose of the Study:

• To apply the Hemodynamic Modality Separation (HMS) method to high-density multichannel (HDM) fNIRS data.
• To investigate the effectiveness of HMS in separating cerebral functional components from physiological noise.
• To explore cerebral activation in the parietal area during a motor task using HMS.

Main Methods:

• Hemodynamic Modality Separation (HMS) was employed, leveraging the differential correlation patterns of oxyhemoglobin (ΔHbO) and deoxyhemoglobin (ΔHbR) changes.
• Negative correlation of ΔHbO and ΔHbR indicates cerebral functional activity, while positive correlation suggests systemic physiological changes.
• The HMS method was applied to high-density multichannel (HDM) fNIRS measurements during a single-sided finger-tapping task in human adults.

Main Results:

• Conventional fNIRS analysis of the parietal area showed unclear signal laterality during the finger-tapping task.
• The functional components separated by the HMS method demonstrated clear localization to the contralateral parietal area.
• HMS successfully enhanced the detection and localization of cerebral activation in the parietal cortex.

Conclusions:

• Hemodynamic Modality Separation (HMS) is an effective technique for isolating neural activity from physiological artifacts in fNIRS data.
• HMS significantly improves the spatial localization of brain activity, particularly in challenging exploratory detection scenarios.
• This study represents the first report of utilizing the HMS method for exploratory cerebral activity detection with HDM NIRS.