High-synchronization wearable fNIRS-EEG system for investigating neurovascular coupling dynamics at millisecond temporal resolution

Here, we report a wearable functional near-infrared spectroscopy-electroencephalogram (fNIRS-EEG) system to overcome the temporal resolution mismatch between the two modalities, enabling precise investigation of neurovascular coupling dynamics (NVC). By implementing an orthogonal encoding and cyclic decoding scheme, the system achieves fNIRS acquisition at up to 1,000 Hz simultaneously with EEG, while maintaining high signal fidelity across 52 optical and 32 electrical channels. Systematic validation through phantom experiments, physiological tests, and auditory-evoked response measurements confirms the system's ability to concurrently capture fast neural activity and hemodynamic correlates. Feature-level correlation analysis further reveals strong links between optical neuronal signals and event-related potentials. This technological advance provides a powerful platform for studying rapid neuronal signals, with broad implications for cognitive neuroscience, clinical diagnostics, and brain-computer interfaces.