Cross-correlation Analysis of the Correspondence between Magnetoencephalographic and Near-infrared Cortical Signals

Summary

Objectives : The study of neurovascular coupling greatly benefits from combined measurements of neuronal and vascular signals. Two-step signal processing is developed to extract parameters describing the coupling.

Methods : Using a magnetometer in an extremely well shielded room a broadband magnetoencephalogram was simultaneously measured with time-resolved nearinfrared spectroscopy during a motor activity paradigm. The raw MEG and NIRS data were denoised separately using independent component analysis.

Results : After averaging the resulting signals showed motor activity-related changes. The temporal correspondence between MEG and NIRS was assessed plotting a combined trajectory and calculating a crosscorrelation. Compared to the MEG signal, at movement onset the NIRS signal showed an onsetdelay in the range of seconds.

Conclusions : Multi-variate signal pre-processing followed by temporal delay estimates demonstrated the extraction of neurovascular coupling parameters.

Keywords

Direct current magnetoencephalography - near-infrared spectroscopy - independent component analysis - cross-correlation - neurovascular coupling

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