Gradient artefact correction in the EEG signal recorded within the fMRI scanner

In recent years, combined EEG-fMRI has become a powerful brain imaging technique which is largely employed in clinical and neuroscience research. Parallel to the achievements reached in this area, a number of challenges remain to be overcome in order to consolidate such technique as an independent and effective method for brain imaging. In particular, the occurrence of gradient artefacts in the EEG signal due to the magnetic field of the fMRI magnetic scanner. This paper presents a proposal for modelling the variability of the gradient artefact template which makes use of the standard deviation and the slope differentiator between consecutive samples of the signals. Combination of such a model with the average artefact subtraction method achieves a reasonable elimination of the gradient artefact from EEG recordings.