Pharmacological dissociation of memory expression and reactivation

BARREIRO K; LYNCH VM; SUAREZ LD; FELD M; CLEMENTE J; MOLINA VA; DELORENZI A

Congreso; Reunión de la Sociedad Argentina de Investigación en Neurociencias; 2012

Sociedad Argentina de Investigación en Neurociencias

It was proposed by Tulving in 1983 that memories must be reactivated first, and then a subsequent process would determine whether they can or cannot be expressed. Reconsolidation approaches open the opportunity to explore whether mechanisms mediating memory reactivation and those that underlie behavioral expression of memory can be dissociated. In the crab Chasmagnathus memory model, animals associate the training context with a visual danger stimulus passing overhead. After a strong training protocol crabs exhibit long term memory 24?96 h later. In this model, a brief exposure (5 minutes) to the training context (reminder) induces labilization and reconsolidation. We studied the effect of pre-reminder administration of glutamate receptors AMPA and NMDA antagonist, CNQX and APV respectively. We found that CNQX (1µg/g) did not impair the behavioral expression of the memory but it did impair reconsolidation. Therefore, as expected, the expressed memory became labile. In contrast, APV (1.5 µg/g) impaired behavioral expression of the memory but did not impair its ability to be reactivated. Hence, these findings suggest that NMDA receptor activation is required for memory expression but not for memory reactivation-labilization. Our findings show that when a memory is retrieved, the respective neuronal trace is reactivated although this trace may not take control over behavior.