title: Hippocampal theta rhythm and its coupling with gamma oscillations require fast inhibition onto parvalbumin-positive interneurons.
abstract: Hippocampal theta (5-10 Hz) and gamma (35-85 Hz) oscillations depend on an inhibitory network of GABAergic interneurons. However, the lack of methods for direct and cell-type-specific interference with inhibition has prevented better insights that help link synaptic and cellular properties with network function. Here, we generated genetically modified mice (PV-Deltagamma(2)) in which synaptic inhibition was ablated in parvalbumin-positive (PV+) interneurons. Hippocampal local field potential and unit recordings in the CA1 area of freely behaving mice revealed that theta rhythm was strongly reduced in these mice. The characteristic coupling of theta and gamma oscillations was strongly altered in PV-Deltagamma(2) mice more than could be accounted for by the reduction in theta rhythm only. Surprisingly, gamma oscillations were not altered. These data indicate that synaptic inhibition onto PV+ interneurons is indispensable for theta- and its coupling to gamma oscillations but not for rhythmic gamma-activity in the hippocampus. Similar alterations in rhythmic activity were obtained in a computational hippocampal network model mimicking the genetic modification, suggesting that intrahippocampal networks might contribute to these effects.
authors.affiliation: Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom.
authors.forename: Peer
authors.initials: P
authors.lastname: Wulff
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Ponomarenko
authors.forename: Marlene
authors.initials: M
authors.lastname: Bartos
authors.forename: Tatiana M
authors.initials: TM
authors.lastname: Korotkova
authors.forename: Elke C
authors.initials: EC
authors.lastname: Fuchs
authors.forename: Florian
authors.initials: F
authors.lastname: Bähner
authors.forename: Martin
authors.initials: M
authors.lastname: Both
authors.forename: Adriano B L
authors.initials: AB
authors.lastname: Tort
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Kopell
authors.forename: William
authors.initials: W
authors.lastname: Wisden
authors.forename: Hannah
authors.initials: H
authors.lastname: Monyer
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D004594:Electrophysiology; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D007395:Interneurons / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008959:Models, Neurological; D010320:Parvalbumins / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D021122:Protein Subunits / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism; D013826:Theta Rhythm; D013997:Time Factors
chemical_list: D010320:Parvalbumins; D021122:Protein Subunits; D011963:Receptors, GABA-A