Reminder effects: the molecular cascade following a reminder in young chicks does not recapitulate that following training on a passive avoidance task

Memory traces, once established, are no longer sensitive to disruption by metabolic inhibitors. However, memories reactivated by reminder are once again vulnerable, in a time-dependent manner, to amnestic treatment. To determine whether the metabolic events following a reminder recapitulate those following initial training we examined the temporal dynamics of amnesia induced by the protein synthesis inhibitor anisomycin and the glycosylation inhibitor 2-deoxygalactose. The effects of both were transient and dependent on time of reminder post-training and time of injection relative to reminder, and differed from those following initial training. 2-[C-14]-deoxyglucose uptake increased in two brain regions, the intermediate medial hyperstriatum ventrale (IMHV) and lobus parolfactorius (LPO) following reminder as it did following training, but the increase was bilateral rather than confined to the left hemisphere and was more marked in LPO than IMHV. C-fos expression after reminder was increased only in the LPO, the chick brain region associated with a late phase of memory processing and recall. Thus although, like initial consolidation, memory processing after reminder is sensitive to inhibitors of protein synthesis and glycosylation, the temporal and pharmacological dynamics indicate differences between these two processes.