Epilepsy is a neurological disorder characterized by recurrent epileptic seizures. In about 30% to 40% of the patients with epilepsy, the seizures are not sufficiently controlled with anti-epileptic drugs (AEDs). Currently, it is still very difficult to predict which patients will respond to AEDs or deep brain stimulation (DBS), another treatment possibility. Research has shown that abnormal functional brain networks could be involved in the development of epilepsy and in the generation and spread of seizures. Gaining more insight into these networks will be useful for the development of new epilepsy therapies and could help to find biomarkers to predict which patients will respond to treatment with AEDs or DBS. In this project, we will combine functional magnetic resonance imaging and intracranial electroencephalography to investigate how functional brain networks change during the development of epilepsy. We will also use new neuromodulation techniques to obtain more information about the epileptic brain network. Then we will investigate whether the severity of epilepsy and the therapeutic effect of AEDs and DBS are related to specific epilepsy-related changes in the brain network and use these relationships to find biomarkers for the development of epilepsy and for responsiveness to treatment with AEDs or DBS.