title: Synchronized spike waves in immature dentate gyrus networks.
abstract: At early developmental stages, immature neuronal networks of the neocortex and hippocampus spontaneously exhibit synchronously oscillating activities, which are believed to play roles in normal circuit maturation. The tissue development of the dentate gyrus (DG) in the hippocampal formation is exceptionally late compared with other brain regions and persists until postnatal periods. Using patch-clamp recording and functional multineuron calcium imaging, we found that the DG networks of postnatal day (P)3-7 mice spontaneously generated traveling waves of action potentials, which were initiated at the upper blade of the granule cell layer and propagated to the lower blade. The propagation was dependent on glutamatergic and electrical synapses, but not on GABAergic receptor activity. Remarkably, the DG waves were almost completely abolished in offspring born to female rats exposed to restraint stress during pregnancy. In the prenatally stressed offspring, DG granule cell dendrites developed normally until P3 and showed atrophy by P9. Thus, the DG waves may be required for the maturation of DG granule cells.
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Seki
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kobayashi
authors.forename: Naoya
authors.initials: N
authors.lastname: Takahashi
authors.forename: Norio
authors.initials: N
authors.lastname: Matsuki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ikegaya
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D020013:Calcium Signaling / Q000502:physiology*; D003344:Cortical Synchronization / Q000502:physiology*; D018891:Dentate Gyrus / Q000254:growth & development*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009415:Nerve Net / Q000254:growth & development*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000503:physiopathology / Q000523:psychology; D013315:Stress, Psychological / Q000503:physiopathology / Q000523:psychology