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

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

Mar del Plata

Congreso; Reunion Anual de la Sociedad Argentina de Investigacion en Neurociencias; 2015

SAN

Over a century of memory studies have presumedthat forgetting was the product of passive mechanisms such as decay andinterference. In the last two decades, however, studies on Retrieval-InducedForgetting (RIF) have demonstrated the existence of active mechanisms ofadaptive forgetting, such as the inhibitory control. Despite this, the lack ofanimal models precluded the understanding of the neurobiological mechanismsunderlying these processes. Using spontaneous object recognition, we developeda paradigm that allowed us to observe retrieval-induced forgetting in rats. Wehave shown that forgetting an item associated with a particular context occursunder conditions which cause competition between memory traces (two pairs ofobjects that share a context as an evocation cue). We used localpharmacological inativation to show that this kind of forgetting requires theactivity of the medial prefrontal cortex (mPFC) in rats; structure homologousto the human dorsolateral prefrontal cortex (DLPFC). By using c-Fos imaging, wealso observed that mPFC activation by retrieval practice occurs only during thefirst practice sessions, providing evidence that, as for humans, forgetting isadaptive also for rats. These results are consistent with the idea that the RIFoccurs via a top-down inhibitory control mechanism exerted by the mPFC onstructures where memory tracesmay be stored.