Frontiers in Systems Neuroscience Systems Neuroscience

Abstract

Electroencephalography is the technique most suited to capture the dynamical properties of a seizure. In some specialized Epilepsy Surgery Units, direct exploration of brain regions using intracerebral depth-electrodes is performed These depth-EEG recordings have long been considered as the " gold standard " for EZ identification. Although they allow for better definition of the EZ, the complete delineation of the EZ may remain elusive, such that suppression of seizures is not always obtained. The reason is that in most of the cases the organization of the EZ is quite complex. This organization corresponds to that of a network of neuronal populations (showing " hyperexcitabilty " and " hypersynchronization " properties) distributed in distinct and distant brain structures. This network is often referred to as the epileptogenic network (Spencer, 2002; Bartolomei et al., 2008b). Accurate identification of epileptogenic networks is the thus the central problem in drug-resistant epilepsies and novel methods have to be proposed to achieve this goal (Wendling et al., 2009). In particular, the demand is high for diagnostic methods allowing for better characterization and interpretation of depth-EEG signals, in terms of underlying neuronal networks and pathophysiological mechanisms taking place in these networks (Rampp and Stefan, 2006).