An appetitive experience after fear memory destabilization attenuates fear retention: involvement GluN2B-NMDA receptors in the Basolateral Amygdala Complex

FERRER MONTI, ROQUE I.; GIACHERO, MARCELO; ALFEI, JOAQUÍN M.; BUENO, ADRIÁN M.; CUADRA, GABRIEL; MOLINA, VICTOR A.

Learning & Memory

Cold Spring Harbor Laboratory Press

Año: 2016 vol. 23 p. 465 - 478

It is known that a well-consolidated memory can return to a labile state and be- come susceptible to interference following reactivation. This instability is followed by a re-stabilization phase termed reconsolidation. In the present study we explored whether an unrelated appetitive experience (voluntary consumption of diluted sucrose) can affect a consolidated contextual fear memory in rats during the retrieval-induced destabilization phase. Our findings show that exposure to an appetitive experience following reactivation interferes with fear memory re-consolidation. This effect was present even after one week. Importantly, this interference was achieved only under reactivation conditions that induced fear memory destabilization. This result could not be explained as a potentiated extinction, because sucrose was unable to deepen extinction or impede reinstatement. Since GluN2B-containing NMDA receptors in the Basolateral Amygdala complex (BLA) had been implicated in triggering fear memory destabilization, we decided to block pharmacologically such receptors in an attempt to explore the neurobiological bases of the observed effect. Intra-basolateral amygdala complex (BLA) infusion with ifenprodil, a GluN2B-NMDA antagonist, prevented the interference caused by the appetitive experience. Hence, the fact that a consolidated fear memory can be dampened by an unrelated emotional experience with opposite valence could be a promising path for an effective and non-invasive treatment of pathological memories.