Memory Reconsolidation after Training of Different Intensities Depends on the Duration of the Reminder Interval

Two series of experiments were run on formation of a conditioned reflex to context in terrestrial snails using two training protocols with different numbers of unconditioned stimuli. In each experimental series, memory reconsolidation was initiated using a “reminder” of the training context at different times – 3 and 6 days after training – with subsequent blockade of protein synthesis with anisomycin. The training context reminder procedure combined with anisomycin injection on post-training day 3 in both protocols led to derangement of memory reconsolidation (forgetting). However, reminding of the training context with protein synthesis blockade on post-training day 6 was followed by retention of the memory in animals given fewer reinforcements during training, indicating that the memory reconsolidation process was not triggered. At the same time, reminders with protein synthesis blockade on post-training day 6 in animals receiving significantly more reinforcements during training led to forgetting, i.e., derangement of normal memory reconsolidation. Thus, these studies showed that reconsolidation of a contextual memory in terrestrial snails depends on training intensity, which is linked with selection of training protocols with different numbers of unconditioned stimuli. It is suggested that consolidation and reconsolidation processes are mediated by different neural pathways.