The Added Value of EEG-fMRI in Imaging Neuroscience

The main objective of functional neuroimaging is to detect and characterize in space and time neurophysiologically relevant changes of brain states. Functional MRI (fMRI) and electro-encephalography (EEG) assume that a given brain state can be decoded from the precise anatomical localization and the detailed temporal evolution of neuro-electrical brain signals, respectively. Mapping brain states with fMRI at a spatial resolution in the millimeter range allows imaging neuroscientists to test diverse neurophysiological and neuropathological hypotheses in the normal and clinical populations. Simultaneously recorded EEG offers the possibility to greatly enrich topological results by tracking subjects’ state-representative patterns over time at the millisecond temporal scale. The main purpose of this chapter is to illustrate how the imaging neuroscientist can integrate detailed temporal information provided by simultaneously recorded EEG signals into fMRI spatio-temporal modeling. We discuss the problem of optimizing a common source space for fMRI and EEG signal projection through the use of anatomical and functional MRI models and EEG distributed inverse models, thereby gathering a fully integrated framework for the comparative analysis of simultaneously acquired EEG-fMRI data sets.