Modulación de la memoria y osmorregulación en chasmagnathus : relación funcional y papel del sistema angiotensinérgico

Fil:Delorenzi, Alejandro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Retrieval under stress decreases the long-term expression of a human declarative memory via reconsolidation

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 20 min 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 24 h 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.Fil: Fernández Larrosa, Pablo Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular. Laboratorio de Fisiología y Biología Molecular; ArgentinaFil: Ojea, Alejandro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular. Laboratorio de Fisiología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Ojea, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Matemática; ArgentinaFil: Molina, Víctor Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Farmacología Experimental de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Farmacología Experimental de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacología; ArgentinaFil: Zorrilla Zubilete, María Aurelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Departamento de Farmacología; ArgentinaFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; Argentin

Choline reverses scopolamine-induced memory impairment by improving memory reconsolidation

It is widely known that pre-training systemic administration of the muscarinic antagonist scopolamine (SCP) (0.5 mg/kg, i.p.) leads to anterograde memory impairment in retention tests. The administration of the α7-nicotinic receptor agonist choline (Ch) in the dorsal hippocampus (0.8 μg/hippocampus) immediately after memory reactivation allowed recovery from scopolamine-induced memory impairment. This effect of Ch was time-dependent, and retention performance was not affected in drug-treated mice that were not subjected to memory reactivation, suggesting that the performance effects are not due to non-specific effects of the drug. The effects of Ch also depended on the age of the reactivated memory. Altogether, our results suggest that Ch exerts its effects by modulating memory reconsolidation, and that the memory impairment induced by low doses of SCP is a memory expression failure and not a storage deficit. Therefore, reconsolidation, among other functions, might serve to change memory expression in later tests. Summarizing, our results open new avenues about the behavioral significance and the physiological functions of memory reconsolidation, providing new strategies for recovering memories from some types of amnesia.Fil: Blake, Mariano Guillermo. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Boccia, Mariano Martin. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Krawczyk, Maria del Carmen. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Delorenzi, Alejandro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Baratti, Carlos Maria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Enhancement of long-term memory expression by a single trial during consolidation

Before the memory trace is stored long term, it must undergo a phase of consolidation during which it remains susceptible to modifications. It has previously been proposed that during consolidation, memories are kept from being stored long term, and can therefore be modified with additional information resulting from ongoing behavior. The Chasmagnathus associative memory model is used here to test whether it is possible during consolidation to modify the long-term expression of a memory generated by a weak training procedure. In this memory model, long-term memory expression is achieved after strong training protocols, a 15-spaced trial procedure. After a weak training protocol (WTP, six spaced trials), crabs do not show memory retention when tested in the long term. Nevertheless, the WTP builds a long-term memory that it is indeed consolidated, but remains unexpressed. Here we show that memory can be modified by experience during this short period after learning: memory expression can be enhanced by a Single Trial Session, on the condition that this session takes place contingent upon the consolidation period. We also found that during this time, the memory built by the WTP is behaviorally expressed, in contrast with what occurs at long term. Our results support the idea that during consolidation memories can be evaluated in the background of concurrent experiences. In particular, we propose that during the consolidation period it is possible for crabs to assess which experiences, among those stored long term, will be expressed long term.Fil: Smal, Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Suárez, Luis Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Updating contextual information during consolidation as result of a new memory trace

Reconsolidation studies have led to the hypothesis that memory, when labile, would be modified in order to incorporate new information. This view has reinstated original propositions suggesting that short-term memory provides the organism with an opportunity to evaluate and rearrange information before storing it, since it is concurrent with the labile state of consolidation. The Chasmagnathus associative memory model is used here to test whether during consolidation it is possible to change some attribute of recently acquired memories. In addition, it is tested whether these changes in behavioral memory features can be explained as modifications on the consolidating memory trace or as a consequence of a new memory trace. We show that short-term memory is, unlike long-term memory, not context specific. During this short period after learning, behavioral memory can be updated in order to incorporate new contextual information. We found that, during this period, the cycloheximide retrograde amnesic effect can be reverted by a single trial in a new context. Finally, by means of memory sensitivity to cycloheximide during consolidation and reconsolidation, we show that the learning of a new context (CS) during this short-term memory period builds up a new memory trace that sustains the behavioral memory update.Fil: Suárez, Luis Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Smal, Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Dissociation between memory reactivation and its behavioral expression: Scopolamine interferes with memory expression without disrupting long-term storage

The reconsolidation hypothesis has challenged the traditional view of fixed memories after consolidation. Reconsolidation studies have disclosed that the mechanisms mediating memory retrieval and the mechanisms that underlie the behavioral expression of memory can be dissociated, offering a new prospect for understanding the nature of experimental amnesia. The muscarinic antagonist scopolamine has been used for decades to induce experimental amnesias The goal of the present study is to determine whether the amnesic effects of scopolamine are due to storage (or retrieval) deficits or, alternatively, to a decrease in the long-term memory expression of a consolidated long-term memory. In the crab Chasmagnathus memory model, we found that scopolamine-induced amnesia can be reverted by facilitation after reminder presentation. This recovery of memory expression was reconsolidation specific since a reminder that does not triggers reconsolidation process did not allow the recovery. A higher dose (5 μg/g) of scopolamine induced an amnesic effect that could not be reverted through reconsolidation, and thus it can be explained as an interference with memory storage and/or retrieval mechanisms. These results, showing that an effective amnesic dose of scopolamine (100. ng/g) negatively modulates long-term memory expression but not memory storage in the crab Chasmagnathus, are consistent with the concept that dissociable processes underlie the mechanisms mediating memory reactivation and the behavioral expression of memory. © 2012 Elsevier Inc.Fil: Caffaro, Pedro Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Suárez, Luis Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Blake, Mariano Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología; ArgentinaFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Neural correlates of expression-independent memories in the crab Neohelice

The neural correlates of memory have been usually examined considering that memory retrieval and memory expression are interchangeable concepts. However, our studies in the crab Neohelice (Chasmagnathus) granulata and in other memory models have shown that memory expression is not necessary for memory to be re-activated and become labile. In order to examine putative neural correlates of memory in the crab Neohelice, we contrast changes induced by training in both animal's behavior and neuronal responses in the medulla terminalis using in vivo Ca2+ imaging. Disruption of long-term memory by the amnesic agents MK-801 or scopolamine (5 μg/g) blocks the learning-induced changes in the Ca2+ responses in the medulla terminalis. Conversely, treatments that lead to an unexpressed but persistent memory (weak training protocol or scopolamine 0.1 μg/g) do not block these learning-induced neural changes. The present results reveal a set of changes in the neural activity induced by training that correlates with memory persistence but not with the probability of this memory to be expressed in the long-term. In addition, the study constitutes the first in vivo evidence in favor of a role of the medulla terminalis in learning and memory in crustaceans, and provides a physiological evidence indicating that memory persistence and the probability of memory to be expressed might involve separate components of memory traces.Fil: Maza, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Locatelli, Fernando Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Angiotensin modulates long-term memory expression but not long-term memory storage in the crab Chasmagnathus

Memory reconsolidation is a dynamic process in which a previously consolidated memory becomes labile following reactivation by a reminder. In a previous study in the crab Chasmagnathus memory model, we showed that a water-shortage episode, via angiotensin modulation during reconsolidation, could reveal a memory that otherwise remains unexpressed: weakly trained animals cannot reveal long-term memory (LTM) except when an episode of noticeable ethological meaning, water deprivation, is contingent upon reconsolidation. However, these results are at variance with two of our previous interpretations: weak training protocols do not build LTM and angiotensin II modulates the strength of the information storing process. A parsimonious hypothesis is that in Chasmagnathus angiotensins regulate LTM expression, but not LTM storage. Here, we tested three predictions of this hypothesis. First, the well-known retrograde amnesic effect of the angiotensin II antagonist saralasin is not due to interference on memory storage, but to modulation of memory expression. Second, the recovery of the LTM memory expression of the apparently amnesic retrograde effect produced by saralasin, through the water-shortage episode contingent upon reconsolidation, must be reconsolidation specific. Consequently, summation-like effects and retrieval deficits cannot explain these results because of the parametric conditions of reconsolidation. Third, weak training protocols build an unexpressed LTM that requires mRNA transcription and translation, a diagnostic characteristic of LTM. Results show that angiotensin modulates LTM expression but not LTM memory storage in the crab Chasmagnathus. The results lead us to suggest that, in Chasmagnathus, LTM expression - the process of gaining appreciable control over behavior of the reactivated trace in the retrieval session - may be considered a distinct attribute of its long-term storage. This strategy, a positive modulation during reconsolidation, is proposed to distinguish between memories that can be reactivated, labilized and are not expressed, and memories that are not stored long term, obliterated or altered in other retrieval mechanisms.Fil: Frenkel, Lia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; ArgentinaFil: Suárez, Luis Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Maldonado, Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

The temporal dynamics of enhancing a human declarative memory during reconsolidation

When a consolidated memory is reactivated, it can become labile and prone to enhancement or disruption, a process known as reconsolidation. The reconsolidation hypothesis has challenged the traditional view that memories after consolidation are fixed and unchangeable. Recent studies suggest that the mechanisms mediating memory retrieval and the mechanisms that underlie the behavioral expression of memory can be dissociated, offering a new promise for the understanding of human memory persistence. Although reconsolidation studies typically use amnesic agents, it has also been shown that memory can be enhanced by pharmacological agents and real-life events during reconsolidation. Recently, we demonstrated that a mild stressor, cold pressor stress (CPS), can enhance human declarative memory during reconsolidation in a cued-recall test. Here we evaluate whether the recollection of 7- or 20-day-old long-term memories can be improved by exposure to two different neuromodulators: a mild stressor and glucose during reconsolidation. As expected, poor and very poor memory performance was found at the time of memory reactivation (days 6 and 20 after training). CPS during reconsolidation improved the long-term expression of a declarative memory 6 -but not 20-days after training. However, the administration of an oral source of glucose (juice), but not a diet juice, can enhance memory during reconsolidation even 20. days after training. Interestingly, when a recognition test was applied instead of a cued-recall test, memory performance was still robust at both 1 and 3. weeks after training. Here we show that the period in which this memory can be reactivated and become labile largely exceeds the period in which that memory is recalled, proving evidence that conscious access is not needed for reconsolidation. Present results are consistent with dissociation between the mechanisms mediating memory labilization and the mechanisms that underlie the behavioral expression of memory.Fil: Coccoz, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Villalón Sandoval, Adolfo. Universidad Andrés Bello; ChileFil: Stehberg, Jimmy. Universidad Andrés Bello; ChileFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Aversive memory conditioning induces fluoxetine-dependent anxiety-like states in the crab Neohelice granulata

The interactions between memory processes and emotions are complex. Our previous investigations in the crab Neohelice led to an adaptation of the affective extension of sometimes opponent processes (AESOP) model. The model proposes that emotions generate separate emotive memory traces, and that the unfolding of emotional responses is a crucial component of the behavioral expression of reactivated memories. Here, we show that an aversive conditioning, that used changes in an innate escape response to an aversive visual stimulus, induced an emotional behavior that endured beyond the stimuli: the aversive memory training built an anxiety-like state evaluated in a dark/light plus-maze. We found that, after the training session, crabs displayed aversion to maze light areas, and an increased time immobilized in the dark zones of the maze, an anxiety-like behavior induced by stressors or physiological conditions in other crustaceans. The training-dependent anxiety-like behavior was blocked by pretraining administration of fluoxetine, suggesting an underlying serotonin-dependent phenomenon. We hypothesize that this training-induced anxiety-like state generates a separate emotive memory trace that is reinstated and crucial for the modulation of memory expression once the memory is reactivated.Fil: Maza, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Urbano Suarez, Francisco Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Delorenzi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin