title: Coherent phasic excitation during hippocampal ripples.
abstract: High-frequency hippocampal network oscillations, or "ripples," are thought to be involved in episodic memory. According to current theories, memory traces are represented by assemblies of principal neurons that are activated during ripple-associated network states. Here we performed in vivo and in vitro experiments to investigate the synaptic mechanisms during ripples. We discovered postsynaptic currents that are phase-locked to ripples and coherent among even distant CA1 pyramidal neurons. These fast currents are consistent with excitatory postsynaptic currents (EPSCs) as they are observed at the equilibrium potential of Cl(-), and they display kinetics characteristic of EPSCs. Furthermore, they survived after intracellular blockade of GABAergic transmission and are effective to regulate the timing of action potentials. In addition, our data show a progressive synchronization of phasic excitation and inhibition during the course of ripples. Together, our results demonstrate the presence of phasic excitation during ripples reflecting an exquisite temporal coordination of assemblies of active pyramidal cells.
authors: Neurowissenschaftliches Forschungszentrum, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
authors: Nikolaus
authors: N
authors: Maier
authors: Alvaro
authors: A
authors: Tejero-Cantero
authors: Anja L
authors: AL
authors: Dorrn
authors: Jochen
authors: J
authors: Winterer
authors: Prateep S
authors: PS
authors: Beed
authors: Genela
authors: G
authors: Morris
authors: Richard
authors: R
authors: Kempter
authors: James F A
authors: JF
authors: Poulet
authors: Christian
authors: C
authors: Leibold
authors: Dietmar
authors: D
authors: Schmitz
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D058256:Brain Waves / Q000187:drug effects / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018756:GABA Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009433:Neural Inhibition / Q000502:physiology; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D018756:GABA Antagonists; D005680:gamma-Aminobutyric Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid