title: Memory of occasional events in rats: individual episodic memory profiles, flexibility, and neural substrate.
abstract: In search for the mechanisms underlying complex forms of human memory, such as episodic recollection, a primary challenge is to develop adequate animal models amenable to neurobiological investigation. Here, we proposed a novel framework and paradigm that provides means to quantitatively evaluate the ability of rats to form and recollect a combined knowledge of what happened, where it happened, and when or in which context it happened (referred to as episodic-like memory) after a few specific episodes in situations as close as possible to a paradigm we recently developed to study episodic memory in humans. In this task, rats have to remember two odor-drink associations (what happened) encountered in distinct locations (where it happened) within two different multisensory enriched environments (in which context/occasion it happened), each characterized by a particular combination of odors and places. By analyzing licking behavior on each drinking port, we characterized quantitatively individual recollection profiles and showed that rats are able to incidentally form and recollect an accurate, long-term integrated episodic-like memory that can last ≥ 24 d after limited exposure to the episodes. Placing rats in a contextually challenging recollection situation at recall reveals the ability for flexible use of episodic memory as described in humans. We further report that reversible inactivation of the dorsal hippocampus during recall disrupts the animal's capacity to recollect the complete episodic memory. Cellular imaging of c-Fos and Zif268 brain activation reveals that episodic memory recollection recruits a specific, distributed network of hippocampal-prefrontal cortex structures that correlates with the accuracy of the integrated recollection performance.
authors.affiliation: Centre National de la Recherche Scientifique, Centre de Neurosciences Paris-Sud, Université Paris-Sud, Unité Mixte de Recherche 8195, F-91405 Orsay, France, Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Veyrac
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Marina
authors.initials: M
authors.lastname: Allerborn
authors.affiliation: Centre National de la Recherche Scientifique, Centre de Neurosciences Paris-Sud, Université Paris-Sud, Unité Mixte de Recherche 8195, F-91405 Orsay, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Gros
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Frederic
authors.identifier: http://orcid.org/0000-0003-1289-2133
authors.initials: F
authors.lastname: Michon
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Louise
authors.initials: L
authors.lastname: Raguet
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Jana
authors.initials: J
authors.lastname: Kenney
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Florette
authors.initials: F
authors.lastname: Godinot
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Thevenet
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Garcia
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France.
authors.forename: Belkacem
authors.initials: B
authors.lastname: Messaoudi
authors.affiliation: Centre National de la Recherche Scientifique, Centre de Neurosciences Paris-Sud, Université Paris-Sud, Unité Mixte de Recherche 8195, F-91405 Orsay, France, nadine.ravel@cnrs.fr serge.laroche@u-psud.fr.
authors.forename: Serge
authors.initials: S
authors.lastname: Laroche
authors.affiliation: Unité Mixte de Recherche 5292, Centre National de la Recherche Scientifique, Institute national de la santé et de la recherche médicale U1028, University Lyon 1, Lyon Neuroscience Research Center, F-69366 Lyon, France nadine.ravel@cnrs.fr serge.laroche@u-psud.fr.
authors.forename: Nadine
authors.identifier: http://orcid.org/0000-0002-0666-4559
authors.initials: N
authors.lastname: Ravel
mesh_terms: D000818:Animals; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping; D004327:Drinking Behavior; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology; D009812:Odorants; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D018709:Statistics, Nonparametric; D014868:Water Deprivation
chemical_list: D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D058785:GABA-A Receptor Agonists; D016760:Proto-Oncogene Proteins c-fos; D009118:Muscimol
keywords: episodic-like memory; hippocampus; olfactory memory; prefrontal cortex; recollection; rodent