Techniques employing this strategy are particularly useful in stimulus- or task-free experimental conditions. Perhaps the most typical example is the interictal spike-related fMRI mapping, in which the interictal epilepiform events manifest themselves as spike-like discharges in EEG [143, 144]. Some other examples have been witnessed in studies exploring the neural substrates underlying the rhythmic modulations in the resting or pathological brain [145–149]. In these studies, predictors for the fMRI regression analysis are derived from frequency-specific EEG modulations. By assessing the correlation between the fMRI signals and the EEG-defined predictors, one may localize the neural regions responsible for the generation of the rhythmic modulations of interest.
