title: Functional Diversity of Subicular Principal Cells during Hippocampal Ripples.
abstract: Cortical and hippocampal oscillations play a crucial role in the encoding, consolidation, and retrieval of memory. Sharp-wave associated ripples have been shown to be necessary for the consolidation of memory. During consolidation, information is transferred from the hippocampus to the neocortex. One of the structures at the interface between hippocampus and neocortex is the subiculum. It is therefore well suited to mediate the transfer and distribution of information from the hippocampus to other areas. By juxtacellular and whole-cell-recordings in awake mice, we show here that in the subiculum a subset of pyramidal cells is activated, whereas another subset is inhibited during ripples. We demonstrate that these functionally different subgroups are predetermined by their cell subtype. Bursting cells are selectively used to transmit information during ripples, whereas the firing probability in regular firing cells is reduced. With multiple patch-clamp recordings in vitro, we show that the cell subtype-specific differences extend into the local network topology. This is reflected in an asymmetric wiring scheme where bursting cells and regular firing cells are recurrently connected among themselves but connections between subtypes exclusively exist from regular to bursting cells. Furthermore, inhibitory connections are more numerous onto regular firing cells than onto bursting cells. We conclude that the network topology contributes to the observed functional diversity of subicular pyramidal cells during sharp-wave associated ripples.
  
  
  CONCLUSIONS
  Memory consolidation is dependent on hippocampal activity patterns, so called hippocampal ripples. During these fast oscillations, memory traces are transferred from the hippocampus to the neocortex via the subiculum. We investigated the role of single cells in the subiculum during ripples and found that, dependent on their subtype, they are preferentially activated or inhibited. In addition, these two subtypes, the bursting and regular firing type, are differentially integrated into the local network: inhibitory cells are more densely connected to regular firing cells, and communication between regular and bursting cells is unidirectional. Together with earlier findings on different preferential target regions of these subtypes, we conclude that memory traces are guided to target regions of the activated cell type.
authors.affiliation: Neuroscience Research Center and dietmar.schmitz@charite.de boehmc@janelia.hhmi.org.
authors.forename: Claudia
authors.initials: C
authors.lastname: Böhm
authors.affiliation: Institute of Neurophysiology, Charité Universitätsmedizin Berlin, 10117 Berlin, Germany.
authors.forename: Yangfan
authors.identifier: http://orcid.org/0000-0002-0317-1353
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Neuroscience Research Center and.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Maier
authors.affiliation: Neuroscience Research Center and.
authors.forename: Jochen
authors.initials: J
authors.lastname: Winterer
authors.affiliation: Neuroscience Research Center and Max-Delbrück Center for Molecular Medicine, 13092 Berlin, Germany, Cluster of Excellence NeuroCure, 10117 Berlin, Germany.
authors.forename: James F A
authors.initials: JF
authors.lastname: Poulet
authors.affiliation: Institute of Neurophysiology, Charité Universitätsmedizin Berlin, 10117 Berlin, Germany, Cluster of Excellence NeuroCure, 10117 Berlin, Germany.
authors.forename: Jörg R P
authors.initials: JR
authors.lastname: Geiger
authors.affiliation: Neuroscience Research Center and Max-Delbrück Center for Molecular Medicine, 13092 Berlin, Germany, Cluster of Excellence NeuroCure, 10117 Berlin, Germany, Bernstein Center for Computational Neuroscience, 10115 Berlin, Germany, and Center for Neurodegenerative Diseases Berlin, 10117 Berlin, Germany dietmar.schmitz@charite.de boehmc@janelia.hhmi.org.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Schmitz
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000367:Age Factors; D000818:Animals; D004558:Electric Stimulation; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology* / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009415:Nerve Net / Q000502:physiology; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology*; D018709:Statistics, Nonparametric
chemical_list: D049452:Green Fluorescent Proteins; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1
keywords: connectivity; hippocampus; in vivo; multiple recordings; oscillation; subiculum