Using cellular resolution recording techniques, we address fundamental questions concerned with the formation, initiation, and progression of epileptic seizures in the intact brain. Epileptic seizures likely arise through the aberrant interaction of local neural populations whose underlying circuitry is not well understood. Despite >100 years of research, even the most basic aspects of epilepsy have escaped our understanding, and up to 30% of patients remain unresponsive to pharmacotherapy. No clear answer exists as to how an epileptic network forms over time, how individual seizures start or terminate, why seizures remain focal in one case, or spread in another. One reason for this persistent lack of understanding has been the technical difficulty to study densely packed epileptic networks at sufficient temporal and spatial resolution. We combine cutting edge cellular scale chronic in vivo calcium imaging with electrophysiology, optogenetics, and behavioral assessment in various models of chronic epilepsy in mice. The core goal of the group is the identification of basic local circuit elements of chronically seizure producing networks that in the best case are shared across different types of epilepsy. At the therapeutic level, we develop novel light-based, targeted therapeutic interventions in close collaboration with other research groups to contain local epileptic activity in the intact brain.