Simultaneous but not independent anisomycin infusions in insular cortex and amygdala hinder stabilization of taste memory when updated

Abstract

Reconsolidation has been described as a process where a consolidated memory returns to a labile state when retrieved. Growing evidence suggests that reconsolidation is, in fact, a destabilization/stabilization process that incorporates updated information to a previously consolidated memory. We used the conditioned taste aversion (CTA) task in order to test this theory. On the first trial, the conditioned stimulus (CS) (saccharin) was associated to the unconditioned stimulus (US) (LiCl injection), and as a result, aversion to saccharin was obtained. The following day, animals were injected with anisomycin in either the insular cortex (IC), central amygdala (CeA), basolateral amygdala (BLA), or simultaneously in IC and CeA or IC and BLA, and a second CTA trial was carried out in which updated information was acquired. Animals were tested 24 h later. When protein synthesis was inhibited in either the IC or CeA, consolidation was affected and previously consolidated memory was unimpaired. However, when both the IC and CeA were simultaneously anisomycin injected, the previously consolidated memory was affected. After repeated association trials, protein synthesis inhibition in the IC and CeA did not have an effect on taste memory. These results suggest that the IC and the CeA are necessary for taste-aversion consolidation, and that both share the previously consolidated memory trace. In addition, our data demonstrated that protein synthesis in either the IC or the CeA suffices to stabilize previously consolidated taste memory when destabilized by incorporation of updated information.