Retrieval is not necessary to trigger reconsolidation of object recognition memory in the perirhinal cortex

Memory retrieval has been considered as requisite to initiate memory reconsolidation; however, some studies indicate that blocking retrieval does not prevent memory from undergoing reconsolidation. Since N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors in the perirhinal cortex have been involved in object recognition memory formation, the present study evaluated whether retrieval and reconsolidation are independent processes by manipulating these glutamate receptors. The results showed that AMPA receptor antagonist infusions in the perirhinal cortex blocked retrieval, but did not affect memory reconsolidation, although NMDA receptor antagonist infusions disrupted reconsolidation even if retrieval was blocked. Importantly, neither of these antagonists disrupted short-term memory. These data suggest that memory underwent reconsolidation even in the absence of retrieval.