Source modeling of the P300 event-related response using magnetoencephalography and electroencephalography measurements

This study aimed to measure the event-related potential P300 with electroencephalography (EEG) and the event-related field P300m with magnetoencephalography (MEG), and to locate the equivalent current sources related to attentional brain function. Multiple equivalent current dipoles were estimated from the P300 and P300m waveforms obtained from visual and somatosensory oddball paradigm tasks. Estimated sources from P300m were located on both sides of the occipito-temporal gyrus for visual stimuli and on the post central gyrus for somatosensory stimuli. The sources of P300m were modality specific. The equivalent current dipoles of P300 were located on the cingulate gyrus and the thalamus in addition to the locations estimated from P300m. However, the dipoles of P300m in MEG were not located on the cingulate gyrus and the thalamus. The discrepancy between EEG and MEG was due to the difficulty to measure radially oriented dipoles in MEG.