title: Awake hippocampal reactivations project onto orthogonal neuronal assemblies.
abstract: The chained activation of neuronal assemblies is thought to support major cognitive processes, including memory. In the hippocampus, this is observed during population bursts often associated with sharp-wave ripples, in the form of an ordered reactivation of neurons. However, the organization and lifetime of these assemblies remain unknown. We used calcium imaging to map patterns of synchronous neuronal activation in the CA1 region of awake mice during runs on a treadmill. The patterns were composed of the recurring activation of anatomically intermingled, but functionally orthogonal, assemblies. These assemblies reactivated discrete temporal segments of neuronal sequences observed during runs and could be stable across consecutive days. A binding of these assemblies into longer chains revealed temporally ordered replay. These modules may represent the default building blocks for encoding or retrieving experience.
authors.affiliation: INMED, INSERM U901, Aix-Marseille Université, Marseille, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Malvache
authors.affiliation: INMED, INSERM U901, Aix-Marseille Université, Marseille, France.
authors.forename: Susanne
authors.initials: S
authors.lastname: Reichinnek
authors.affiliation: INMED, INSERM U901, Aix-Marseille Université, Marseille, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Villette
authors.affiliation: INMED, INSERM U901, Aix-Marseille Université, Marseille, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Haimerl
authors.affiliation: INMED, INSERM U901, Aix-Marseille Université, Marseille, France. rosa.cossart@inserm.fr.
authors.forename: Rosa
authors.initials: R
authors.lastname: Cossart
mesh_terms: D000818:Animals; D001931:Brain Mapping; D056547:CA1 Region, Hippocampal / Q000737:chemistry / Q000166:cytology* / Q000502:physiology*; D020013:Calcium Signaling; D005080:Exercise Test; D008297:Male; D051379:Mice; D009415:Nerve Net / Q000166:cytology* / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology; D012420:Running; D014851:Wakefulness / Q000502:physiology*