Local driving and global interactions in the progression of seizure dynamics

The dynamics underlying epileptic seizures are well understood. We present a novel analysis of seizure-like events (SLEs) in an \textit{ex vivo} whole hippocampus, as well as a modeling study that sheds light on the underlying network dynamics. We show that every SLE can be divided into two phases. During the first, SLE dynamics are driven by the intra-network interaction of a network exhibiting high internal synchrony. The second phase is characterized by lead switching, with the leading region exhibiting low internal synchrony. We show that the second phase dynamics are driven by inter-network feedback among multiple regions of the hippocampus.