Cross-correlation analysis of the correspondence between magnetoencephalographic and near-infrared cortical signals

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 magnetoencephalogrom was simultaneously measured with time-resolved near-infrared 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 NIBS signal showed an onset delay in the range of seconds. Conclusions: Multi-variate signal pre-processing followed by temporal delay estimates demonstrated the extraction of neurovascular coupling parameters.