title: Long-term effects of interference on short-term memory performance in the rat.
abstract: A distinction has always been made between long-term and short-term memory (also now called working memory, WM). The obvious difference between these two kinds of memory concerns the duration of information storage: information is supposedly transiently stored in WM while it is considered durably consolidated into long-term memory. It is well acknowledged that the content of WM is erased and reset after a short time, to prevent irrelevant information from proactively interfering with newly stored information. In the present study, we used typical WM radial maze tasks to question the brief lifespan of spatial WM content in rodents. Groups of rats were submitted to one of two different WM tasks in a radial maze: a WM task involving the repetitive presentation of a same pair of arms expected to induce a high level of proactive interference (PI) (HIWM task), or a task using a different pair in each trial expected to induce a low level of PI (LIWM task). Performance was effectively lower in the HIWM group than in LIWM in the final trial of each training session, indicative of a "within-session/short-term" PI effect. However, we also observed a different "between-session/long-term" PI effect between the two groups: while performance of LIWM trained rats remained stable over days, the performance of HIWM rats dropped after 10 days of training, and this impairment was visible from the very first trial of the day, hence not attributable to within-session PI. We also showed that a 24 hour-gap across training sessions known to allow consolidation processes to unfold, was a necessary and sufficient condition for the long-term PI effect to occur. These findings suggest that in the HIWM task, WM content was not entirely reset between training sessions and that, in specific conditions, WM content can outlast its purpose by being stored more permanently, generating a long-term deleterious effect of PI. The alternative explanation is that WM content could be transferred and stored more permanently in an intermediary form or memory between WM and long-term memory.
authors.affiliation: Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center (CRNL), University Lyon 1, Lyon, France.
authors.forename: Mégane
authors.initials: M
authors.lastname: Missaire
authors.affiliation: Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center (CRNL), University Lyon 1, Lyon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Fraize
authors.affiliation: Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center (CRNL), University Lyon 1, Lyon, France.
authors.forename: Mickaël Antoine
authors.initials: MA
authors.lastname: Joseph
authors.affiliation: Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center (CRNL), University Lyon 1, Lyon, France.
authors.forename: Al Mahdy
authors.initials: AM
authors.lastname: Hamieh
authors.affiliation: Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center (CRNL), University Lyon 1, Lyon, France.|Centre National de la Recherche Scientifique (CNRS), Lyon, France.|Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon, France.
authors.forename: Régis
authors.initials: R
authors.lastname: Parmentier
authors.affiliation: Neurocentre Magendie, INSERM U1215, Université de Bordeaux, Bordeaux, France.
authors.forename: Aline
authors.initials: A
authors.lastname: Marighetto
authors.affiliation: Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center (CRNL), University Lyon 1, Lyon, France.|Centre National de la Recherche Scientifique (CNRS), Lyon, France.|Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon, France.
authors.forename: Paul Antoine
authors.initials: PA
authors.lastname: Salin
authors.affiliation: Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center (CRNL), University Lyon 1, Lyon, France.|Centre National de la Recherche Scientifique (CNRS), Lyon, France.|Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon, France.
authors.forename: Gaël
authors.initials: G
authors.lastname: Malleret
mesh_terms: D000818:Animals; D057567:Memory, Long-Term; D008570:Memory, Short-Term; D011334:Proactive Inhibition; D051381:Rats