Investigating Brain Connectivity and Information Flow in Mental Workload Using EEG and fNIRS Integration

TL;DR

This study combines EEG and fNIRS to analyze brain connectivity during mental workload, revealing increased frontal connectivity and directional neural influence, advancing understanding of neurovascular coupling under cognitive load.

Contribution

It introduces an integrated EEG-fNIRS approach to assess functional and effective brain connectivity during mental workload, highlighting directional information flow and neurovascular interactions.

Findings

Increased frontal connectivity during high MWL

Significant directional influence from EEG to fNIRS signals

Connectivity patterns differ between low and high MWL states

Abstract

This study investigates brain connectivity and information flow during mental workload (MWL) by integrating electroencephalogram (EEG) and functional near-infrared spectroscopy (fNIRS) signals. Utilizing the N-back task to induce varying levels of MWL in 26 participants, we analyzed both functional and effective connectivity across 25 cortical regions derived from combined EEG and fNIRS signals. Functional connectivity was assessed using Pearson Correlation Coefficient (PCC), Phase Locking Value (PLV), and Magnitude Squared Coherence (MSC), while effective connectivity was evaluated using directed Directed Transfer Function (dDTF) and generalized Partial Directed Coherence (gPDC). Our findings reveal increased functional connectivity in frontal regions during higher MWL conditions (3-back compared to 0-back). Furthermore, effective connectivity analysis demonstrates a significant directional information flow from EEG to fNIRS, indicating a dominant influence of neural activity on hemodynamic responses. Statistical tests confirm significant differences in connectivity patterns between low and high MWL states. These results underscore the utility of EEG-fNIRS integration for characterizing brain network dynamics under varying cognitive demands and provide insights into neurovascular coupling mechanisms during mental workload.