Comparison of fMRI activation and EEG source localization using beamformers during motor response in the Stroop task: Preliminary results

The simultaneous measurement of neuro-functional MRI and EEG provides the opportunity to investigate both haemodynamic and electrical activity in the human brain non-invasively. This multimodal technique makes it possible to combine the advantages of EEG (millisecond temporal resolution) with those of fMRI (millimeter spatial accuracy). However, the combination of EEG and fMRI suffers also from their limitations: there is no clear relationship between neuronal activity, the EEG and the fMRI signals; mismatches are observed between EEG and fMRI analyses and there are experimental limitations. In this study we present a qualitative analysis of simultaneous acquired EEG/fMRI data from a single subject performing the Stroop task. The EEG data and the fMRI time series are processed separately focused on the motor responses. We apply a beamformer spatial filter to the EEG data to localize the electrical activity corresponding to the motor responses of the right and the left hand. The areas of maximum electrical activation are compared with the fMRI activation clusters. Both analyses show activation around the primary motor cortex. These results are an indication to start with a more sophisticated and integrated analysis of simultaneous acquired EEG/fMRI data during the Stroop task.