However, this is not meant to guarantee the success of multimodal neuroimaging. Existing theories fail to explain every aspect of the explosively expanding imaging datasets documented in thousands of research articles. To date, the primary bottleneck is still more fundamental than technical. Methodologies that rest on an assumed or modeled physiological linkage between fMRI and EEG/MEG, almost certainly fail under particular circumstances when the linkage is invalid. On one hand, theoretical modeling and experimental investigation need to be performed across microscopic, mesoscopic and macroscopic scales, and proceed in parallel to further solidify the physiological and physical basis for the multimodal integration. On the other hand, careful considerations should be taken in experimental designs to justify the rationale of combining different modalities, regardless of whatever algorithms are used to fuse the multimodal datasets. Cautions have to be taken as well in the interpretation of the imaging results.
