title: Phase-Locked Inhibition, but Not Excitation, Underlies Hippocampal Ripple Oscillations in Awake Mice In Vivo.
abstract: Sharp wave-ripple (SWR) oscillations play a key role in memory consolidation during non-rapid eye movement sleep, immobility, and consummatory behavior. However, whether temporally modulated synaptic excitation or inhibition underlies the ripples is controversial. To address this question, we performed simultaneous recordings of excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) and local field potentials (LFPs) in the CA1 region of awake mice in vivo. During SWRs, inhibition dominated over excitation, with a peak conductance ratio of 4.1 ± 0.5. Furthermore, the amplitude of SWR-associated IPSCs was positively correlated with SWR magnitude, whereas that of EPSCs was not. Finally, phase analysis indicated that IPSCs were phase-locked to individual ripple cycles, whereas EPSCs were uniformly distributed in phase space. Optogenetic inhibition indicated that PV+interneurons provided a major contribution to SWR-associated IPSCs. Thus, phasic inhibition, but not excitation, shapes SWR oscillations in the hippocampal CA1 region in vivo.
authors.affiliation: IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
authors.forename: Jian
authors.initials: J
authors.lastname: Gan
authors.affiliation: IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Weng
authors.affiliation: IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Pernía-Andrade
authors.affiliation: IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
authors.forename: Jozsef
authors.initials: J
authors.lastname: Csicsvari
authors.affiliation: IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria. Electronic address: peter.jonas@ist.ac.at.
authors.forename: Peter
authors.initials: P
authors.lastname: Jonas
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000502:physiology*; D058407:Electroencephalography Phase Synchronization; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology*; D007395:Interneurons / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D009433:Neural Inhibition; D062308:Optogenetics; D010320:Parvalbumins / Q000378:metabolism; D014851:Wakefulness
chemical_list: D010320:Parvalbumins
keywords: CA1 region; EPSCs; GABAergic synapses; IPSCs; PV(+) interneurons; hippocampus; in vivo recording; in vivo voltage clamp; network oscillations; sharp wave-ripples