CONICET | Buscador de Institutos y Recursos Humanos

The idea that memories are not invariable after the consolidation process has led to new perspectivesabout several mnemonic processes. In this framework, we review our studies on the modulation ofmemory expression during reconsolidation. We propose that during both memory consolidation andreconsolidation, neuromodulators can determine the probability of the memory trace to guide behavior,i.e. they can either increase or decrease its behavioral expressibility without affecting the potential ofpersistent memories to be activated and become labile. Our hypothesis is based on the findings that positivemodulation of memory expression during reconsolidation occurs even if memories are behaviorallyunexpressed. This review discusses the original approach taken in the studies of the crab Neohelice(Chasmagnathus) granulata, which was then successfully applied to test the hypothesis in rodent fearmemory. Data presented offers a new way of thinking about both weak trainings and experimental amnesia:memory retrieval can be dissociated from memory expression. Furthermore, the strategy presentedhere allowed us to show in human declarative memory that the periods in which long-term memorycan be activated and become labile during reconsolidation exceeds the periods in which that memory isexpressed, providing direct evidence that conscious access to memory is not needed for reconsolidation.Specific controls based on the constraints of reminders to trigger reconsolidation allow us to distinguishbetween obliterated and unexpressed but activated long-term memories after amnesic treatments, weaktrainings and forgetting. In the hypothesis discussed, memory expressibility ? the outcome of experiencedependentchanges in the potential to behave ? is considered as a flexible and modulable attribute of longtermmemories. Expression seems to be just one of the possible fates of re-activated memories.