TY - JOUR T1 - Abnormal UP/DOWN membrane potential dynamics coupled with the neocortical slow oscillation in dentate granule cells during the latent phase of temporal lobe epilepsy JF - eneuro JO - eneuro DO - 10.1523/ENEURO.0017-16.2016 SP - ENEURO.0017-16.2016 AU - David W. Ouedraogo AU - Pierre-Pascal Lenck-Santini AU - Geoffrey Marti AU - David Robbe AU - Valérie Crépel AU - Jérôme Epsztein Y1 - 2016/05/06 UR - http://www.eneuro.org/content/early/2016/05/09/ENEURO.0017-16.2016.abstract N2 - The dentate gyrus, a major entry point to the hippocampus, gates (or filters) incoming information from the cortex. During sleep or anesthesia, the slow wave oscillation (SWO) orchestrates hippocampo-neocortical communication, which is important for memory formation. The dentate gate is altered in temporal lobe epilepsy (TLE) early during epileptogenesis, which favors the propagation of pathological activities. Yet whether the gating of physiological SWO by dentate granule cells (DGCs) is altered in TLE has remained unexplored. We combined intracellular recordings of DGCs’ membrane potential (Vm) and local field potential recordings of the SWO in parietal cortex in anesthetized rats early during epileptogenesis (post-SE rats). As expected, in control rats, DGCs’ Vm weakly and rarely oscillated in the SWO frequency range. In contrast, in post-SE rats, DGCs’ Vm displayed strong and long-lasting SWO. In these cells, clear UP and DOWN states, in phase with the neocortical SWO, led to a bimodal Vm distribution. In post-SE rats, DGCs’ firing was increased and more temporally modulated by the neocortical SWO. We conclude that UP/DOWN state dynamics dominate DGCs’ Vm and firing early during epileptogenesis. This abnormally strong neocortical influence on DGCs’ dynamics may profoundly modify the hippocampo-neocortical dialogue during sleep and associated cognitive functions.Significance statement: Communication between cortex and hippocampus during sleep, orchestrated by neocortical slow wave oscillation (SWO), is important for memory consolidation. Whether this communication is affected in temporal lobe epilepsy, a disease with profound memory impairments, is not known. In control rats, dentate granule cells (DGCs), at the gate of the hippocampus, filter incoming information from the cortex. This relative independence of hippocampal neurons from SWO allows the replay of hippocampal specific information independently from the neocortex. Here using in vivo whole-cell patch-clamp recordings of DGCs and field recordings in the neocortex we report an abnormally strong influence of neocortical SWO on DGCs’ membrane potential and firing in post-SE rats. This could profoundly alter hippocampo-neocortical dialogue during sleep and associated cognitive functions. ER -