title: Dynamics of high-frequency synchronization during seizures.
abstract: Pathological synchronization of neuronal firing is considered to be an inherent property of epileptic seizures. However, it remains unclear whether the synchrony increases for the high-frequency multiunit activity as well as for the local field potentials (LFPs). We present spatio-temporal analysis of synchronization during epileptiform activity using wide-band (up to 2,000 Hz) spectral analysis of multielectrode array recordings at up to 60 locations throughout the mouse hippocampus in vitro. Our study revealed a prominent structure of LFP profiles during epileptiform discharges, triggered by elevated extracellular potassium, with characteristic distribution of current sinks and sources with respect to anatomical structure. The cross-coherence of high-frequency activity (500-2,000 Hz) across channels was reduced during epileptic bursts compared with baseline activity and showed the opposite trend for lower frequencies. Furthermore, the magnitude of cross-coherence during epileptiform activity was dependent on distance: electrodes closer to the epileptic foci showed increased cross-coherence and electrodes further away showed reduced cross-coherence for high-frequency activity. These experimental observations were re-created and supported in a computational model. Our study suggests that different intrinsic and synaptic processes can mediate paroxysmal synchronization at low, medium, and high frequencies.
authors: Department of Cell Biology and Neuroscience, University of California, Riverside, California 92521, USA.
authors: Giri P
authors: GP
authors: Krishnan
authors: Gregory
authors: G
authors: Filatov
authors: Maxim
authors: M
authors: Bazhenov
mesh_terms: D000818:Animals; D058256:Brain Waves; D058407:Electroencephalography Phase Synchronization; D006624:Hippocampus / Q000503:physiopathology; D051379:Mice; D011188:Potassium / Q000378:metabolism; D012640:Seizures / Q000503:physiopathology*
chemical_list: D011188:Potassium
keywords: epilepsy; high-frequency activity; seizure; synchrony