An analysis of MEG artifacts caused by heartbeat

Magnetoencephalography (MEG) directly measures the magnetic field caused by neural current activity, with a high temporal resolution. However, its amplitude is very weak and contaminated by various artifacts. One of the such an artifact is caused by heartbeat. In this study, we measured MEG and electrocardiogram (ECG) simultaneously. MEG was averaged with respect to an onset of ECG, that is, the peak of R-wave. Then, we applied equivalent current dipole (ECD) method to estimate current sources of artifacts caused by heartbeat. In addition, we propose a probabilistic model to remove such artifacts and applied to artificial data in order to confirm the efficiency of the method.