Rationale

While the EEG has excellent temporal resolutions, relying on intracranial EEGs may result in so-called cortical myopia, since subcortical and white matter potentials are rarely recorded or analyzed. fMRI and, while limited in temporal resolutions, provide excellent insight into subcortical structures. As the floating sensation cannot be perceived naturally at the bedside—we relied on the analysis of seed-based functional connectivity. The cortical evoked potentials represent multisynaptic local field connectivity uniquely beyond anatomical (bundles) or functional (co-activation) measures. Some view it as a more accurate representation of common-sense connectivity or effective connectivity, but it requires current injection. Hence, we believe our multimodal mapping approach provides together an incomparable spatial and temporal view of networks underlying observed phenomena.

Other methodological details are available in Additional file 3.