title: Hub GABA neurons mediate gamma-frequency oscillations at ictal-like event onset in the immature hippocampus.
abstract: Gamma-frequency oscillations (GFOs, >40 Hz) are a general network signature at seizure onset at all stages of development, with possible deleterious consequences in the immature brain. At early developmental stages, the simultaneous occurrence of GFOs in different brain regions suggests the existence of a long-ranging synchronizing mechanism at seizure onset. Here, we show that hippocamposeptal (HS) neurons, which are GABA long-range projection neurons, are mandatory to drive the firing of hippocampal interneurons in a high-frequency regime at the onset of epileptiform discharges in the intact, immature septohippocampal formation. The synchronized firing of interneurons in turn produces GFOs, which are abolished after the elimination of a small number of HS neurons. Because they provide the necessary fast conduit for pacing large neuronal populations and display intra- and extrahippocampal long-range projections, HS neurons appear to belong to the class of hub cells that play a crucial role in the synchronization of developing networks.
authors.affiliation: Institut de Neurosciences des Systèmes, INSERM UMR1106, Faculté de Médecine La Timone, 27 Boulevard Jean Moulin, 13005 Marseille, France.
authors.forename: Pascale P
authors.initials: PP
authors.lastname: Quilichini
authors.forename: Michel
authors.initials: M
authors.lastname: Le Van Quyen
authors.forename: Anton
authors.initials: A
authors.lastname: Ivanov
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Turner
authors.forename: Aurélie
authors.initials: A
authors.lastname: Carabalona
authors.forename: Henri
authors.initials: H
authors.lastname: Gozlan
authors.forename: Monique
authors.initials: M
authors.lastname: Esclapez
authors.forename: Christophe
authors.initials: C
authors.lastname: Bernard
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000367:Age Factors; D000818:Animals; D003344:Cortical Synchronization / Q000502:physiology*; D004827:Epilepsy / Q000503:physiopathology*; D059330:GABAergic Neurons / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development* / Q000502:physiology; D066298:In Vitro Techniques; D007395:Interneurons / Q000502:physiology; D051379:Mice; D009415:Nerve Net / Q000166:cytology / Q000502:physiology; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D020665:Septum of Brain / Q000166:cytology / Q000254:growth & development / Q000502:physiology