title: Phase-dependent molecular requirements for memory reconsolidation: differential roles for protein synthesis and protein kinase A activity.
abstract: After consolidation, a process that requires gene expression and protein synthesis, memories are stable and highly resistant to disruption by amnestic influences. Recently, consolidated memory has been shown to become labile again after retrieval and to require a phase of reconsolidation to be preserved. New findings, showing that the dependence of reconsolidation on protein synthesis decreases with the age of memory, point to changing molecular requirements for reconsolidation during memory maturation. We examined this possibility by comparing the roles of protein synthesis (a general molecular requirement for memory consolidation) and the activation of protein kinase A (PKA) (a specific molecular requirement for memory consolidation), in memory reconsolidation at two time points after training. Using associative learning in Lymnaea, we show that reconsolidation after the retrieval of consolidated memory at both 6 and 24 h requires protein synthesis. In contrast, only reconsolidation at 6 h after training, but not at 24 h, requires PKA activity, which is in agreement with the measured retrieval-induced PKA activation at 6 h. This phase-dependent differential molecular requirement for reconsolidation supports the notion that even seemingly consolidated memories undergo further selective molecular maturation processes, which may only be detected by analyzing the role of specific pathways in memory reconsolidation after retrieval.
authors.affiliation: Sussex Centre for Neuroscience, Department of Biology and Environmental Sciences, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom. G.Kemenes@sussex.ac.uk
authors.forename: György
authors.initials: G
authors.lastname: Kemenes
authors.forename: Ildikó
authors.initials: I
authors.lastname: Kemenes
authors.forename: Maximilian
authors.initials: M
authors.lastname: Michel
authors.forename: Andrea
authors.initials: A
authors.lastname: Papp
authors.forename: Uli
authors.initials: U
authors.lastname: Müller
mesh_terms: D000818:Animals; D001245:Association Learning; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D008195:Lymnaea; D008568:Memory / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D013997:Time Factors
chemical_list: D009419:Nerve Tissue Proteins; D017868:Cyclic AMP-Dependent Protein Kinases