title: Superficial layers of the medial entorhinal cortex replay independently of the hippocampus.
abstract: The hippocampus is thought to initiate systems-wide mnemonic processes through the reactivation of previously acquired spatial and episodic memory traces, which can recruit the entorhinal cortex as a first stage of memory redistribution to other brain areas. Hippocampal reactivation occurs during sharp wave-ripples, in which synchronous network firing encodes sequences of places. We investigated the coordination of this replay by recording assembly activity simultaneously in the CA1 region of the hippocampus and superficial layers of the medial entorhinal cortex. We found that entorhinal cell assemblies can replay trajectories independently of the hippocampus and sharp wave-ripples. This suggests that the hippocampus is not the sole initiator of spatial and episodic memory trace reactivation. Memory systems involved in these processes may include nonhierarchical, parallel components.
authors.affiliation: Institute of Science and Technology Austria (IST Austria), Am Campus 1, A-3400 Klosterneuburg, Austria. jozsef.csicsvari@ist.ac.at joneill@ist.ac.at.
authors.forename: J
authors.initials: J
authors.lastname: O'Neill
authors.affiliation: Institute of Science and Technology Austria (IST Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
authors.forename: C N
authors.initials: CN
authors.lastname: Boccara
authors.affiliation: Institute of Science and Technology Austria (IST Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Stella
authors.affiliation: Institute of Science and Technology Austria (IST Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Schoenenberger
authors.affiliation: Institute of Science and Technology Austria (IST Austria), Am Campus 1, A-3400 Klosterneuburg, Austria. jozsef.csicsvari@ist.ac.at joneill@ist.ac.at.
authors.forename: J
authors.initials: J
authors.lastname: Csicsvari
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000502:physiology*; D018728:Entorhinal Cortex / Q000166:cytology / Q000502:physiology*; D005071:Evoked Potentials; D008297:Male; D051381:Rats; D065852:Spatial Memory / Q000502:physiology*