title: Retrieval under stress decreases the long-term expression of a human declarative memory via reconsolidation.
abstract: Acute stress impairs memory retrieval of several types of memories. An increase in glucocorticoids, several minutes after stressful events, is described as essential to the impairing retrieval-effects of stressors. Moreover, memory retrieval under stress can have long-term consequences. Through what process does the reactivated memory under stress, despite the disrupting retrieval effects, modify long-term memories? The reconsolidation hypothesis proposes that a previously consolidated memory reactivated by a reminder enters a vulnerability phase (labilization) during which it is transiently sensitive to modulation, followed by a re-stabilization phase. However, previous studies show that the expression of memories during reminder sessions is not a condition to trigger the reconsolidation process since unexpressed memories can be reactivated and labilized. Here we evaluate whether it is possible to reactivate-labilize a memory under the impairing-effects of a mild stressor. We used a paradigm of human declarative memory whose reminder structure allows us to differentiate between a reactivated-labile memory state and a reactivated but non-labile state. Subjects memorized a list of five cue-syllables associated with their respective response-syllables. Seventy-two hours later, results showed that the retrieval of the paired-associate memory was impaired when tested 20min after a mild stressor (cold pressor stress (CPS)) administration, coincident with cortisol levels increase. Then, we investigated the long-term effects of CPS administration prior to the reminder session. Under conditions where the reminder initiates the reconsolidation process, CPS impaired the long-term memory expression tested 24h later. In contrast, CPS did not show effects when administered before a reminder session that does not trigger reconsolidation. Results showed that memory reactivation-labilization occurs even when retrieval was impaired. Memory reactivation under stress could hinder -via reconsolidation- the probability of the traces to be expressed in the long term.
authors.affiliation: Laboratorio de Neurobiología de la Memoria, Departamento de Fisiología y Biología Molecular y Celular, IFIByNE-CONICET, Pabellón II, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria C1428EHA, Argentina.
authors.forename: Pablo Nicolás Fernández
authors.initials: PNF
authors.lastname: Larrosa
authors.affiliation: Laboratorio de Neurobiología de la Memoria, Departamento de Fisiología y Biología Molecular y Celular, IFIByNE-CONICET, Pabellón II, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria C1428EHA, Argentina.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Ojea
authors.affiliation: Departamento de Matemática, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires - Inst. de Investigaciones Matemáticas "Luis A. Santalo ́", CONICET-UBA, Argentina. Electronic address: iojea@dm.uba.ar.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Ojea
authors.affiliation: Departamento de Farmacología, Facultad de Ciencias Químicas, IFEC-CONICET-Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina. Electronic address: vmolina@fcq.unc.edu.ar.
authors.forename: Victor Alejandro
authors.initials: VA
authors.lastname: Molina
authors.affiliation: Centro de Estudios Farmacológicos y Botánicos (CEFYBO - CONICET), Departamento de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Argentina. Electronic address: zorrilla@fmed.uba.ar.
authors.forename: María Aurelia
authors.initials: MA
authors.lastname: Zorrilla-Zubilete
authors.affiliation: Laboratorio de Neurobiología de la Memoria, Departamento de Fisiología y Biología Molecular y Celular, IFIByNE-CONICET, Pabellón II, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria C1428EHA, Argentina. Electronic address: delorenzi@fbmc.fcen.uba.ar.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Delorenzi
mesh_terms: D001245:Association Learning / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D003080:Cold Temperature; D003463:Cues; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D008297:Male; D000069077:Memory Consolidation / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology*; D009483:Neuropsychological Tests; D012463:Saliva / Q000737:chemistry; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D006854:Hydrocortisone
keywords: Memory; Memory expression; Reactivation; Reconsolidation; Retrieval