For the validation of the method, we analyzed data collected in a visual oddball task. In a previous study, the same data had been used to investigate the trial-to-trial changes of P300 intensity [Mantini et al., 2009], without taking into account the latency of the P300 component. Conversely, the intensity changes across trials are cancelled out by averaging with the proposed EEG-fMRI method, whereas the difference in latency of the different ERP components is investigated. The application of the method to visual oddball data provided a high-resolution spatio-temporal characterization of the P300 neuronal activations across distinct cortical networks. We observed that the detection of rare targets stimulated a complex limbic-parieto-frontal system, involving the visual, the core and the ventral attention networks. The differences found in the activation timing across their areas confirm that different brain functions could be dynamically engaged, and can be related to the different ERP components elicited by the oddball task.
