Constrained ICA based ballistocardiogram and electro-oculogram artifacts removal from visual evoked potential EEG signals measured inside MRI

In the simultaneous acquisition of EEG and fMRI, analysis of EEG signals is a difficult task due to ballistocardiogram (BCG) and electro-oculogram (EOG) artifacts. It gets worse if evoked potentials are measured inside MRI for their minute responses in comparison to the spontaneous brain responses. In this paper, we propose a new method for removing both artifacts simultaneously from the evoked EEG signals acquired inside MRI using constrained Independent component analysis (cICA). With properly designed reference functions for the BCG and EOG artifacts as constraints, cICA identifies the independent components (ICs) corresponding to the artifacts. Then artifact-removed EEG signals are reconstructed after removing the identified ICs to obtain evoked potentials. To evaluate our proposed technique, we have removed the artifacts with cICA and the standard template subtraction technique and generated visual evoked potentials (VEPs) respectively which are compared to the VEPs obtained from EEG signals measured outside MRI. Our results indicate that our cICA technique performs better than the standard BCG artifact removal methods with some efficient features.