Functional connectivity and plasticity changes in focal epileptogenic zones

Abstract-Text (inklusive Referenzen und Bildunterschriften)

Resective surgery is a highly effective treatment option for selected patients with refractory focal epilepsy. However, the efficacy of epilepsy surgery requires the complete resection of the epileptogenic zone (EZ) defined as the region indispensable for generating seizures. In current clinical practice, the identification of the EZ relies on scalp EEG, intraoperative electrocorticography, and long-term intracranial recordings providing sensitive, yet unspecific biomarkers for epileptogenic brain activity. Currently epileptiform potentials (EP) and high frequency oscillations (HFO) are used for delineating the EZ during epilepsy surgery. However, since both these biomarkers can be recorded beyond the seizure onset zone (SOZ), they might yield misleading results regarding the borders of the EZ. We therefore, set out to find properties inherent to the local microcircuitry in the EZ. As a first step we developed computational models inferring functional connectivity and synaptic plasticity between single neurons. Using data from single unit activity in intracranially recorded epilepsy patients, in a second step we now aim at defining properties of microcircuitry connectivity in EZ versus healthy tissue. With this study we widen our understanding of the basic functional changes leading to epileptogenicity on a microscale level and provide further objective electrophysiological biomarkers to distinguish epileptogenic tissue from heathy brain.