Epileptogenic systems: from neocortical sources to scalp EEG signals

In this study, we modelled the EEG signals recorded from the scalp when rapid discharges (in the gamma band) are generated in the neocortex. Using computer simulations, we examined the `observability′ of these rapid discharges: under what conditions (related to the spatiotemporal configuration of the underlying cortical sources) and to what extent are they visible in simulated signals? We could identify some of the factors that may facilitate or impair the recording of rapid discharges in scalp EEG, which constitute an essential marker of brain regions involved at the onset of seizures in partial epilepsies.