Long-term effects of interference on short-term memory performance in the rat
PLoS ONE. 2017-03-13; 12(3): e0173834
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1. PLoS One. 2017 Mar 13;12(3):e0173834. doi: 10.1371/journal.pone.0173834.
Long-term effects of interference on short-term memory performance in the rat.
Missaire M(1), Fraize N(1), Joseph MA(1), Hamieh AM(1), Parmentier R(1)(2)(3),
Marighetto A(4), Salin PA(1)(2)(3), Malleret G(1)(2)(3).
(1)Forgetting and Cortical Dynamics Team, Lyon Neuroscience Research Center
(CRNL), University Lyon 1, Lyon, France.
(2)Centre National de la Recherche Scientifique (CNRS), Lyon, France.
(3)Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon,
(4)Neurocentre Magendie, INSERM U1215, Université de Bordeaux, Bordeaux, France.
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.
PMID: 28288205 [Indexed for MEDLINE]