A modified oddball paradigm for investigation of neural correlates of attention: a simultaneous ERP-fMRI study

The objective of the presented study was to develop and evaluate a P300 experimental protocol for simultaneous registration of event-related potentials (ERPs) and functional MRI (fMRI) data with continuous imaging. It may be useful for investigating attention and working memory processes in specific populations, such as children and neuropsychiatric patients. Eleven children were investigated with simultaneous ERP-fMRI. To fulfill requirements of both BOLD and electroencephalographic signal registration, a modified oddball task was used. To verify the ERP-fMRI protocol we also performed a study outside the scanner using a typical two-stimuli oddball paradigm. Localization of the P300 component of ERPs partially corresponded with fMRI results in the frontal and parietal brain regions. FMRI activations were found in: middle frontal gyrus, insula, SMA, parietal lobule, thalamus, and cerebellum. Our modified oddball task provided ERP-fMRI results with high level of significance (EEG SNR = 35, fMRI p < 0.05-Bonf.). ERPs obtained in the scanner were comparable with those registered outside the scanner, although some differences in the amplitude were noticed, mainly in the N100 component. In our opinion the presented paradigm may be successfully applied for simultaneous ERP-fMRI registration of neural correlates of attention in vulnerable populations.