1Advanced MRI Section, Laboratory of Functional and Molecular Imaging, NINDS, National Institutes of Health, Bethesda, MD, United States
We propose a subspace method to analyze simultaneous EEG and fMRI at rest. It is based on the notion that the neuro-electrical activity underlying the fMRI signal may have EEG spectral features that report on regional neuronal dynamics and inter-regional interactions. We found characteristic spectral signatures in the EEG correlates of spontaneous fMRI signals at individual regions as well as the temporal correlation among regions. These spectral signatures not only allowed us to parcel the brain into clusters that resembled the established functional subdivisions, but also offered important clues for disentangling the involvement of individual regions in fMRI network activity.