Multimodal Imaging in Epilepsy: Combining EEG and fMRI

This chapter introduces a multimodal imaging approach to “epileptic networks”. It is explained why electroencephalography (EEG) in combination with functional magnetic resonance imaging (fMRI) is an ideal tool to study spontaneous brain activity such as spontaneously occurring interictal epileptic discharges, typical sleep graphoelements, or characteristic EEG oscillations. This is closely related to resting state brain activity in healthy subjects and has been studied via analysis of spontaneous neuronal oscillations and their fMRI correlates. The application of EEG/fMRI to disease, with epilepsy as the primary example, is reviewed. It starts from the original goal, the identification of the region of the brain in which interictal epileptic activity arises, moves on to studies not in line with this idea but introducing the new concept that fMRI maps may reflect entire epileptic networks, and finally to the clinical applicability of EEG/fMRI patient studies and publications suggesting the method may provide insight into the neurobiology of epilepsy. The chapter concludes with a look into the future: intracranial EEG/fMRI.

Keywords: Resting network, epilepsy, inter-ictal, temporal lobe, methodology, conscious states, epileptogenic zone.