This Privat Docent thesis presents three of my recent studies that explore the development and the mechanisms of large-scale epileptic networks in the kainate mouse model of TLE using high density EEG combined to multiple intracerebral recordings. We reveal that a large-scale epileptic network develops and invade both hemispheres, generating epileptic patterns and altering functional connectivity at the whole brain level. We further show that low frequency synchronization and cross frequency coupling are key mechanisms at works in these large-scale pathologic networks. To introduce these works, I first discuss the fundamental, clinical and translational scientific contributions summarizing current knowledge and providing new insight on the large-scale aspects of focal epilepsies, with a particular focus on mesial temporal lobe epilepsies.