EXPRESSION: ONE OF THE POSSIBLE FATES OF REACTIVATED LONG-TERM MEMORIES

A. DELORENZI; F. MAZA; V. MOLINA; J. STEHBERG; P. N. FERNÁNDEZ LARROSA; A. OJEA

montevideo

Congreso; XII International Congress of Neuroethology.; 2016

The idea that memories are variable after the consolidation process has led to new perspectives about the memory processes. In this framework, our numerous studies (reviewed in Delorenzi et al, J Physiol Paris. 2014) in the crab Neohelice (Chasmagnathus) granulata and humans allow us to propose that during both memory consolidation and reconsolidation, neuromodulators can determine the probability of the memory trace to guide behavior, without affecting the potential of persistent memories to be activated and become labile. Our hypothesis is based on the findings that positive modulation of memory expression during reconsolidation occurs even if memories are behaviorally unexpressed.Based on experimental data, here we presented a different way of thinking about persistent but unexpressed long-term memories following either weak trainings or some experimental amnesia. The hypothesis includes the view that memory expression during retrievals sessions can be dissociatedfrom memory reactivation. Furthermore, the strategy presented here allowed us to show in human declarative memory that the periods in which long-term memory can be activated and become labile during reconsolidation exceeds the periods in which that memory is expressed, providing direct evidence that the expression of memory is not needed for reconsolidation. Specific controls based on the constraints of reminders to trigger reconsolidation allow us to distinguish between obliterated and unexpressed but activated long-term memories after amnesic treatments, weak trainings and forgetting. In the hypothesis discussed, memory expressibility--the outcome of experience-dependent changes in the potential to behave--is considered as a flexible and modulable attribute of long-term memories.