-Development of a retrieval-induced forgetting paradigm in rodents to model adaptive forgetting in the mammalian brain

GALLO FRANCISCO; MORICI FACUNDO; MAGDALENA MIRANDA; MICHAEL ANDERSON; NOELIA V WEISSTAUB; BEKINSCHTEIN, PEDRO

Mar del Plata

Congreso; XXX Reunion Anual de la Sociedad Argentina de Investigaciones en Neurociencias; 2015

Sociedad Argentina de Investigaciones en Neurociencias

Over a century of memory studies have presumed that forgetting was the product ofpassive mechanisms such as decay and interference. In the last two decades, however,studies on Retrieval-Induced Forgetting (RIF) have demonstrated the existence of activemechanisms of adaptive forgetting, such as the inhibitory control. Despite this, the lack ofanimal models precluded the understanding of the neurobiological mechanisms underlyingthese processes. Using spontaneous object recognition, we developed a paradigm thatallowed us to observe retrieval-induced forgetting in rats. We have shown that forgettingan item associated with a particular context occurs under conditions which causecompetition between memory traces (two pairs of objects that share a context as anevocation cue). We used local pharmacological inactivation to show that this kind offorgetting requires the activity of the medial prefrontal cortex (mPFC) in rats; structurehomologous to the human dorsolateral prefrontal cortex (DLPFC). By using c-Fos imaging,we also observed that mPFC activation by retrieval practice occurs only during the firstpractice sessions, providing evidence that, as for humans, forgetting is adaptive also forrats. These results are consistent with the idea that the RIF occurs via a top-downinhibitory control mechanism exerted by the mPFC on structures where memory tracesmay be stored.