1
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Pomi A, Lin J, Mizraji E. A memory access gate controlled by dynamic contexts. Biosystems 2024; 241:105232. [PMID: 38754622 DOI: 10.1016/j.biosystems.2024.105232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/18/2024]
Abstract
Temporary difficulties in accessing the contents of memories are a common experience in everyday life, for example, when we try to recognize a known person in an unusual context. In addition, recent experiments seem to indicate that retrograde amnesia in the early stages of Alzheimer's disease is due to disorders in accessing memories that were installed normally. These facts suggest the existence of an intermediate step between the stimulus arrival and the associative recognition. In this work, a multimodular neurocomputational model is presented postulating the existence of a neural gate that controls the access of the stimulus with its context to the consolidated memory. If recognition is not achieved, a random search is initiated in a contextual network aroused by the initial context. The search continues until the appropriate context that allows for recognition is found or until the process is turned off because the initial stimulus is no longer maintained in the working memory. The model is based on vector patterns of neural activity and context-dependent matrix memories. Simple Markov chain simulations are presented to exemplify possible search scenarios in the contextual network. Finally, we discuss some of the characteristics of the model and the phenomenon under study.
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Affiliation(s)
- Andrés Pomi
- Group of Cognitive Systems Modeling, Biophysics and Systems Biology Section, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay.
| | - Juan Lin
- Group of Cognitive Systems Modeling, Biophysics and Systems Biology Section, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay; Physics Department, Washington College, Chestertown, MD, 21620, USA
| | - Eduardo Mizraji
- Group of Cognitive Systems Modeling, Biophysics and Systems Biology Section, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay
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2
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Hildebrandt H, Eling P. Comments on energy conservation treatments for MS-related fatigue and a new proposal. J Neurol Sci 2024; 461:123040. [PMID: 38735103 DOI: 10.1016/j.jns.2024.123040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/11/2024] [Accepted: 05/07/2024] [Indexed: 05/14/2024]
Abstract
Psychological treatments of MS-related fatigue mostly depend on energy conservation programs. We argue that the evidence for energy conservation training is weak - in contrast to some reviews on this topic. The reasons for our concerns are the use of informed passive control groups allowing negative placebo effects, the lack of predefined primary outcome parameter, statistically rather than clinically significant effects, and the use of insensitive fatigue questionnaires. We propose to base psychological interventions not on a view of fatigue as a constant loss of mental energy but as a subjective representation ("feeling") of an inflammatory state, which draws away attentional capacity. This conceptualization allows to develop a three-step treatment approach: Getting short-term control on fatigue, extinction to reduce fatigue-related avoidance behavior, and a systematic increase of activities by pacing. Our proposal depends on the techniques, that can interrupt ongoing feelings of fatigue and can serve as a basis for extinction. We propose that Progressive Muscle Relaxation might be such a technique. The advantage of our model is that it shares similarities with well-established treatments for phobias and chronic pain and we discuss the shared set of assumptions. Hopefully, this will help to improve the treatment of fatigue in future.
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Affiliation(s)
- Helmut Hildebrandt
- Klinikum Bremen-Ost, Department of Neurology, Bremen, Germany; Institute of Psychology, University of Oldenburg, Oldenburg, Germany.
| | - Paul Eling
- Donders Institute for Brain, Cognition and Behavior, Radboud University, Nijmegen, the Netherlands
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3
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Wang CM, Wu CY, Lin CE, Hsu MC, Lin JC, Huang CC, Lien TY, Lin HK, Chang TW, Chiang HC. Forgotten memory storage and retrieval in Drosophila. Nat Commun 2023; 14:7153. [PMID: 37935667 PMCID: PMC10630420 DOI: 10.1038/s41467-023-42753-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 10/20/2023] [Indexed: 11/09/2023] Open
Abstract
Inaccessibility of stored memory in ensemble cells through the forgetting process causes animals to be unable to respond to natural recalling cues. While accumulating evidence has demonstrated that reactivating memory-stored cells can switch cells from an inaccessible state to an accessible form and lead to recall of previously learned information, the underlying cellular and molecular mechanisms remain elusive. The current study used Drosophila as a model to demonstrate that the memory of one-trial aversive olfactory conditioning, although inaccessible within a few hours after learning, is stored in KCαβ and retrievable after mild retraining. One-trial aversive conditioning triggers protein synthesis to form a long-lasting cellular memory trace, approximately 20 days, via creb in KCαβ, and a transient cellular memory trace, approximately one day, via orb in MBON-α3. PPL1-α3 negatively regulates forgotten one-trial conditioning memory retrieval. The current study demonstrated that KCαβ, PPL1-α3, and MBON-α3 collaboratively regulate the formation of forgotten one-cycle aversive conditioning memory formation and retrieval.
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Affiliation(s)
- Chih-Ming Wang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
- Brain Research Center, National Tsing Hua University, Hsinchu, Taiwan, ROC
| | - Chun-Yuan Wu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Chen-En Lin
- Department of Medicine, National Cheng-Kung University, Tainan, Taiwan, ROC
| | - Ming-Chi Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
- Brain Research Center, National Tsing Hua University, Hsinchu, Taiwan, ROC
| | - Jing-Chun Lin
- Department of Medicine, National Cheng-Kung University, Tainan, Taiwan, ROC
| | - Chuan-Chin Huang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
- Brain Research Center, National Tsing Hua University, Hsinchu, Taiwan, ROC
| | - Ting-Yu Lien
- Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan, ROC
| | - Hsin-Kai Lin
- Department of Medicine, National Cheng-Kung University, Tainan, Taiwan, ROC
| | - Ting-Wei Chang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
- Brain Research Center, National Tsing Hua University, Hsinchu, Taiwan, ROC
| | - Hsueh-Cheng Chiang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC.
- Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan, ROC.
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4
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Autore L, O'Leary JD, Ortega-de San Luis C, Ryan TJ. Adaptive expression of engrams by retroactive interference. Cell Rep 2023; 42:112999. [PMID: 37590145 DOI: 10.1016/j.celrep.2023.112999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/17/2023] [Accepted: 08/01/2023] [Indexed: 08/19/2023] Open
Abstract
Long-term memories are stored as configurations of neuronal ensembles, termed engrams. Although investigation of engram cell properties and functionality in memory recall has been extensive, less is known about how engram cells are affected by forgetting. We describe a form of interference-based forgetting using an object memory behavioral paradigm. By using activity-dependent cell labeling, we show that although retroactive interference results in decreased engram cell reactivation during recall trials, optogenetic stimulation of the labeled engram cells is sufficient to induce memory retrieval. Forgotten engrams may be reinstated via the presentation of similar or related environmental information. Furthermore, we demonstrate that engram activity is necessary for interference to occur. Taken together, these findings indicate that retroactive interference modules engram expression in a manner that is both reversible and updatable. Inference may constitute a form of adaptive forgetting where, in everyday life, new perceptual and environmental inputs modulate the natural forgetting process.
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Affiliation(s)
- Livia Autore
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - James D O'Leary
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Clara Ortega-de San Luis
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Tomás J Ryan
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland; Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Melbourne, VIC, Australia; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON, Canada.
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5
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Miller RR. The Illusion of Pure Reason in Science: A Cautionary Note. Behav Processes 2023; 207:104863. [PMID: 36965606 DOI: 10.1016/j.beproc.2023.104863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 03/27/2023]
Abstract
Introspection tells people that their behavior is both consciously reasoned and functional (i.e., rational), at least based on the evidence available to them. In contrast, research has found that much human behavior reported to be consciously determined, is strongly influenced by heuristics and the mechanistic principles of associative learning that usually function unconsciously and are sometimes sub-optimal. Scientists are trained to base their conclusions on a rational analysis of evidence, which enhances the scientific validity of their conclusions. But scientific training appears to do little to constrain the role of unconscious heuristics. The present point is that scientists are humans and, as such, they are subject to the influence of heuristics in their scientific conclusions just as laypeople are in their everyday behavior. As an example, the availability heuristic and how it seemingly feeds the repetition-induced truth effect are described. One consequence of this is that failures to replicate frequently cited papers do little to devalue the irreplicable reports. Although unconscious heuristics influence the scientific thinking of researchers, scientists are typically unaware of the role of these heuristics due to their operating below the horizon of introspection. This appears to explain the persistence, in light of overwhelming evidence to the contrary, of the views by many researchers that 'a prediction error is necessary for learning' and that 'reactivated memories have to be reconsolidated to be retained for future access.'
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Zhao J, Zhang X, Zhao B, Hu W, Diao T, Wang L, Zhong Y, Li Q. Genetic dissection of mutual interference between two consecutive learning tasks in Drosophila. eLife 2023; 12:83516. [PMID: 36897069 PMCID: PMC10030115 DOI: 10.7554/elife.83516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 03/09/2023] [Indexed: 03/11/2023] Open
Abstract
Animals can continuously learn different tasks to adapt to changing environments and, therefore, have strategies to effectively cope with inter-task interference, including both proactive interference (Pro-I) and retroactive interference (Retro-I). Many biological mechanisms are known to contribute to learning, memory, and forgetting for a single task, however, mechanisms involved only when learning sequential different tasks are relatively poorly understood. Here, we dissect the respective molecular mechanisms of Pro-I and Retro-I between two consecutive associative learning tasks in Drosophila. Pro-I is more sensitive to an inter-task interval (ITI) than Retro-I. They occur together at short ITI (<20 min), while only Retro-I remains significant at ITI beyond 20 min. Acutely overexpressing Corkscrew (CSW), an evolutionarily conserved protein tyrosine phosphatase SHP2, in mushroom body (MB) neurons reduces Pro-I, whereas acute knockdown of CSW exacerbates Pro-I. Such function of CSW is further found to rely on the γ subset of MB neurons and the downstream Raf/MAPK pathway. In contrast, manipulating CSW does not affect Retro-I as well as a single learning task. Interestingly, manipulation of Rac1, a molecule that regulates Retro-I, does not affect Pro-I. Thus, our findings suggest that learning different tasks consecutively triggers distinct molecular mechanisms to tune proactive and retroactive interference.
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Affiliation(s)
- Jianjian Zhao
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Xuchen Zhang
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Bohan Zhao
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Wantong Hu
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Tongxin Diao
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Liyuan Wang
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Yi Zhong
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Qian Li
- School of Life Sciences, IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
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7
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Pacozzi L, Knüsel L, Ruch S, Henke K. Inverse forgetting in unconscious episodic memory. Sci Rep 2022; 12:20595. [PMID: 36446829 PMCID: PMC9709067 DOI: 10.1038/s41598-022-25100-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Forming memories of experienced episodes calls upon the episodic memory system. Episodic encoding may proceed with and without awareness of episodes. While up to 60% of consciously encoded episodes are forgotten after 10 h, the fate of unconsciously encoded episodes is unknown. Here we track over 10 h, which are filled with sleep or daytime activities, the retention of unconsciously and consciously experienced episodes. The episodes were displayed in cartoon clips that were presented weakly and strongly masked for conscious and unconscious encoding, respectively. Clip retention was tested for distinct clips directly after encoding, 3 min and 10 h after encoding using a forced-choice test that demands deliberate responses in both consciousness conditions. When encoding was conscious, retrieval accuracy decreased by 25% from 3 min to 10 h, irrespective of sleep or wakefulness. When encoding was unconscious, retrieval accuracy increased from 3 min to 10 h and depended on sleep. Hence, opposite to the classic forgetting curve, unconsciously acquired episodic memories strengthen over time and hinge on sleep on the day of learning to gain influence over human behavior.
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Affiliation(s)
- Luca Pacozzi
- grid.5734.50000 0001 0726 5157Institute of Psychology, University of Bern, 3012 Bern, Switzerland
| | - Leona Knüsel
- grid.5734.50000 0001 0726 5157Institute of Psychology, University of Bern, 3012 Bern, Switzerland
| | - Simon Ruch
- grid.10392.390000 0001 2190 1447Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, University Hospital and University of Tuebingen, 72076 Tübingen, Germany
| | - Katharina Henke
- grid.5734.50000 0001 0726 5157Institute of Psychology, University of Bern, 3012 Bern, Switzerland
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8
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Appraising reconsolidation theory and its empirical validation. Psychon Bull Rev 2022; 30:450-463. [PMID: 36085236 PMCID: PMC7614440 DOI: 10.3758/s13423-022-02173-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2022] [Indexed: 11/08/2022]
Abstract
Re-exposure to elements of prior experiences can create opportunities for inducing amnesia for those events. The dominant theoretical framework posits that such re-exposure can result in memory destabilization, making the memory representation temporarily sensitive to disruption while it awaits reconsolidation. If true, such a mechanism that allows for memories to be permanently changed could have important implications for the treatment of several forms of psychopathology. However, there have been contradictory findings and elusive occurrences of replication failures within the "reconsolidation" field. Considering its potential relevance for clinical applications, the fact that this "hot" research area is being dominated by a single mechanistic theory, and the presence of unexplainable contradictory findings, we believe that it is both useful and timely to critically evaluate the reconsolidation framework. We discuss potential issues that may arise from how reconsolidation interference has typically been deducted from behavioral observations, and provide a principled assessment of reconsolidation theory that illustrates that the theory and its proposed boundary conditions are vaguely defined, which has made it close to impossible to refute reconsolidation theory. We advocate for caution, encouraging researchers not to blindly assume that a reconsolidation process must underlie their findings, and pointing out the risks of doing so. Finally, we suggest concrete theoretical and methodological advances that can promote a fruitful translation of reminder-dependent amnesia into clinical treatment.
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9
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Gisquet-Verrier P. Can Forgetting Be Due to Changes in Engram Cell Plasticity? Front Behav Neurosci 2022; 16:945985. [PMID: 35874646 PMCID: PMC9302596 DOI: 10.3389/fnbeh.2022.945985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
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10
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Vivian K, Strodl E, Kitamura H, Johnson L. Memory reconsolidation therapy for comorbid bulimia nervosa and traumatic memories: a case series study. CLIN PSYCHOL-UK 2022. [DOI: 10.1080/13284207.2022.2065913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Katie Vivian
- School of Psychology and Counselling, Queensland University of Technology, Queensland, Australia
| | - Esben Strodl
- School of Psychology and Counselling, Queensland University of Technology, Queensland, Australia
| | - Haruka Kitamura
- School of Psychology and Counselling, Queensland University of Technology, Queensland, Australia
| | - Luke Johnson
- School of Medicine/Division of Psychology, University of Tasmania, Tasmania, Australia
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11
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Ortega-de San Luis C, Ryan TJ. Understanding the physical basis of memory: Molecular mechanisms of the engram. J Biol Chem 2022; 298:101866. [PMID: 35346687 PMCID: PMC9065729 DOI: 10.1016/j.jbc.2022.101866] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/08/2022] [Accepted: 03/11/2022] [Indexed: 12/18/2022] Open
Abstract
Memory, defined as the storage and use of learned information in the brain, is necessary to modulate behavior and critical for animals to adapt to their environments and survive. Despite being a cornerstone of brain function, questions surrounding the molecular and cellular mechanisms of how information is encoded, stored, and recalled remain largely unanswered. One widely held theory is that an engram is formed by a group of neurons that are active during learning, which undergoes biochemical and physical changes to store information in a stable state, and that are later reactivated during recall of the memory. In the past decade, the development of engram labeling methodologies has proven useful to investigate the biology of memory at the molecular and cellular levels. Engram technology allows the study of individual memories associated with particular experiences and their evolution over time, with enough experimental resolution to discriminate between different memory processes: learning (encoding), consolidation (the passage from short-term to long-term memories), and storage (the maintenance of memory in the brain). Here, we review the current understanding of memory formation at a molecular and cellular level by focusing on insights provided using engram technology.
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Affiliation(s)
- Clara Ortega-de San Luis
- School of Biochemistry and Immunology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland.
| | - Tomás J Ryan
- School of Biochemistry and Immunology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland; Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, Victoria, Australia; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, Canada.
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12
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Beisel JMS, Maza FJ, Justel N, Larrosa PNF, Delorenzi A. Embodiment of an Emotional State Concurs with a Stress-Induced Reconsolidation Impairment Effect on an Auditory Verbal Word-List Memory. Neuroscience 2022; 497:239-256. [PMID: 35472504 DOI: 10.1016/j.neuroscience.2022.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 04/12/2022] [Accepted: 04/13/2022] [Indexed: 12/12/2022]
Abstract
Stress alters memory. Understanding how and when acute stress improves or impairs memory is a challenge. Stressors can affect memory depending on a combination of factors. Typically, mild stressors and stress hormones might promote consolidation of memory processing and impair memory retrieval. However, studies have shown that during reconsolidation, stressors may either enhance or impair recalled memory. We propose that a function of reconsolidation is to induce changes in the behavioral expression of memory. Here, we adapted the Rey Auditory Verbal Learning Test (RAVLT) to evaluate the effect of cold pressor stress (CPS) during the reconsolidation of this declarative memory. A decay in memory performance attributable to forgetting was found at the time of memory reactivation 5 d after training (day 6). Contrary to our initial predictions, the administration of CPS after memory reactivation impaired long-term memory expression (day 7), an effect dependent on the presence of a mismatch during Reactivation Session. No differences in recognition tests were found. To assess putative sources of the negative memory modulation effects induced during reconsolidation, current emotional state was evaluated immediately after Testing Session (day 7). An increase in arousal was revealed only when CPS was administered concurrently with memory reactivation-labilization. The possibility of integration during reconsolidation of independent associations of these emotive components in the trace is a critical factor in modulating neutral memories during reconsolidation by stressors.
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Affiliation(s)
- Jessica Mariel Sánchez Beisel
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Pabellón IFIBYNE, Argentina
| | - Francisco Javier Maza
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Pabellón IFIBYNE, Argentina
| | - Nadia Justel
- Lab. Interdisciplinario de Neurociencia Cognitiva (LINC), CEMSC3, ICIFI, UNSAM CONICET, Argentina
| | - Pablo Nicolas Fernandez Larrosa
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Pabellón IFIBYNE, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Argentina.
| | - Alejandro Delorenzi
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Pabellón IFIBYNE, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Argentina.
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13
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Ryan TJ, Frankland PW. Forgetting as a form of adaptive engram cell plasticity. Nat Rev Neurosci 2022; 23:173-186. [PMID: 35027710 DOI: 10.1038/s41583-021-00548-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2021] [Indexed: 12/30/2022]
Abstract
One leading hypothesis suggests that memories are stored in ensembles of neurons (or 'engram cells') and that successful recall involves reactivation of these ensembles. A logical extension of this idea is that forgetting occurs when engram cells cannot be reactivated. Forms of 'natural forgetting' vary considerably in terms of their underlying mechanisms, time course and reversibility. However, we suggest that all forms of forgetting involve circuit remodelling that switches engram cells from an accessible state (where they can be reactivated by natural recall cues) to an inaccessible state (where they cannot). In many cases, forgetting rates are modulated by environmental conditions and we therefore propose that forgetting is a form of neuroplasticity that alters engram cell accessibility in a manner that is sensitive to mismatches between expectations and the environment. Moreover, we hypothesize that disease states associated with forgetting may hijack natural forgetting mechanisms, resulting in reduced engram cell accessibility and memory loss.
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Affiliation(s)
- Tomás J Ryan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland. .,Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland. .,Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Melbourne, Victoria, Australia. .,Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, Canada.
| | - Paul W Frankland
- Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, Canada. .,Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada. .,Department of Psychology, University of Toronto, Toronto, Ontario, Canada. .,Department of Physiology, University of Toronto, Toronto, Ontario, Canada. .,Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.
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14
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Abstract
This article reviews recent findings from the author’s laboratory that may provide new insights into how habits are made and broken. Habits are extensively practiced behaviors that are automatically evoked by antecedent cues and performed without their goal (or reinforcer) “in mind.” Goal-directed actions, in contrast, are instrumental behaviors that are performed because their goal is remembered and valued. New results suggest that actions may transition to habit after extended practice when conditions encourage reduced attention to the behavior. Consistent with theories of attention and learning, a behavior may command less attention (and become habitual) as its reinforcer becomes well-predicted by cues in the environment; habit learning is prevented if presentation of the reinforcer is uncertain. Other results suggest that habits are not permanent, and that goal-direction can be restored by several environmental manipulations, including exposure to unexpected reinforcers or context change. Habits are more context-dependent than goal-directed actions are. Habit learning causes retroactive interference in a way that is reminiscent of extinction: It inhibits, but does not erase, goal-direction in a context-dependent way. The findings have implications for the understanding of habitual and goal-directed control of behavior as well as disordered behaviors like addictions.
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