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Merlo SA, Belluscio MA, Pedreira ME, Merlo E. Memory persistence: from fundamental mechanisms to translational opportunities. Transl Psychiatry 2024; 14:98. [PMID: 38355584 PMCID: PMC10867010 DOI: 10.1038/s41398-024-02808-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 01/05/2024] [Accepted: 01/25/2024] [Indexed: 02/16/2024] Open
Abstract
Memory persistence is a double edge sword. Persistence of adaptive memories is essential for survival and even determines who we are. Neurodegenerative conditions with significant memory loss such as Alzheimer's disease, testify how defects of memory persistence have severe and irreversible effects on personality, among other symptoms. Yet, maintenance of overly strong maladaptive memories underlies highly debilitating psychiatric conditions including post-traumatic stress disorder, specific phobia, substance dependence and binge eating disorder. Here we review the neurobiological mechanisms supporting memory formation, persistence, inhibition and forgetting. We then shift the focus to how such mechanisms have been exploited to alter the persistence of laboratory-generated memories in human healthy volunteers as a proof of concept. Finally, we review the effect of behavioural and pharmacological interventions in anxiety and addiction disorder patients, highlighting key findings, gaps, and future directions for basic and translational research.
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Affiliation(s)
- Santiago Abel Merlo
- Instituto de Fisiología, Biología Molecular y Neurociencias, Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Fisiología y Biofísica Bernardo Houssay, Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad de Buenos Aires, Buenos Aires, Argentina
- Laboratorio Bases Neuronales del Comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mariano Andrés Belluscio
- Instituto de Fisiología y Biofísica Bernardo Houssay, Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad de Buenos Aires, Buenos Aires, Argentina
- Laboratorio Bases Neuronales del Comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Maria Eugenia Pedreira
- Instituto de Fisiología, Biología Molecular y Neurociencias, Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad de Buenos Aires, Buenos Aires, Argentina
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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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Arkell D, Groves I, Wood ER, Hardt O. The Black Box effect: sensory stimulation after learning interferes with the retention of long-term object location memory in rats. ACTA ACUST UNITED AC 2021; 28:390-399. [PMID: 34526383 PMCID: PMC8456983 DOI: 10.1101/lm.053256.120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 07/06/2021] [Indexed: 11/29/2022]
Abstract
Reducing sensory experiences during the period that immediately follows learning improves long-term memory retention in healthy humans, and even preserves memory in patients with amnesia. To date, it is entirely unclear why this is the case, and identifying the neurobiological mechanisms underpinning this effect requires suitable animal models, which are currently lacking. Here, we describe a straightforward experimental procedure in rats that future studies can use to directly address this issue. Using this method, we replicated the central findings on quiet wakefulness obtained in humans: We show that rats that spent 1 h alone in a familiar dark and quiet chamber (the Black Box) after exploring two objects in an open field expressed long-term memory for the object locations 6 h later, while rats that instead directly went back into their home cage with their cage mates did not. We discovered that both visual stimulation and being together with conspecifics contributed to the memory loss in the home cage, as exposing rats either to light or to a cage mate in the Black Box was sufficient to disrupt memory for object locations. Our results suggest that in both rats and humans, everyday sensory experiences that normally follow learning in natural settings can interfere with processes that promote long-term memory retention, thereby causing forgetting in form of retroactive interference. The processes involved in this effect are not sleep-dependent because we prevented sleep in periods of reduced sensory experience. Our findings, which also have implications for research practices, describe a potentially useful method to study the neurobiological mechanisms that might explain why normal sensory processing after learning impairs memory both in healthy humans and in patients suffering from amnesia.
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Affiliation(s)
- Daisy Arkell
- Centre for Discovery Brain Science, School of Medicine, The University of Edinburgh, Edingurgh, Scotland EH8 9XD, United Kingdom.,The Simons Initiative for the Developing Brain, The Patrick Wild Centre, The University of Edinburgh, Edingurgh, Scotland EH8 9XD, United Kingdom
| | - Isabelle Groves
- Department of Psychology, McGill University, Montréal, Quebec H3A 1G1, Canada
| | - Emma R Wood
- Centre for Discovery Brain Science, School of Medicine, The University of Edinburgh, Edingurgh, Scotland EH8 9XD, United Kingdom.,The Simons Initiative for the Developing Brain, The Patrick Wild Centre, The University of Edinburgh, Edingurgh, Scotland EH8 9XD, United Kingdom
| | - Oliver Hardt
- Centre for Discovery Brain Science, School of Medicine, The University of Edinburgh, Edingurgh, Scotland EH8 9XD, United Kingdom.,The Simons Initiative for the Developing Brain, The Patrick Wild Centre, The University of Edinburgh, Edingurgh, Scotland EH8 9XD, United Kingdom.,Department of Psychology, McGill University, Montréal, Quebec H3A 1G1, Canada
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Aggleton JP, Nelson AJD. Distributed interactive brain circuits for object-in-place memory: A place for time? Brain Neurosci Adv 2020; 4:2398212820933471. [PMID: 32954003 PMCID: PMC7479857 DOI: 10.1177/2398212820933471] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/15/2020] [Indexed: 12/23/2022] Open
Abstract
Rodents will spontaneously learn the location of an individual object, an
ability captured by the object-in-place test. This review considers
the network of structures supporting this behavioural test, as well as
some potential confounds that may affect interpretation. A
hierarchical approach is adopted, as we first consider those brain
regions necessary for two simpler, ‘precursor’ tests (object
recognition and object location). It is evident that performing the
object-in-place test requires an array of areas additional to those
required for object recognition or object location. These additional
areas include the rodent medial prefrontal cortex and two thalamic
nuclei (nucleus reuniens and the medial dorsal nucleus), both densely
interconnected with prefrontal areas. Consequently, despite the need
for object and location information to be integrated for the
object-in-place test, for example, via the hippocampus, other
contributions are necessary. These contributions stem from how
object-in-place is a test of associative recognition, as none of the
individual elements in the test phase are novel. Parallels between the
structures required for object-in-place and for recency
discriminations, along with a re-examination of the demands of the
object-in-place test, signal the integration of temporal information
within what is usually regarded as a spatial-object test.
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Affiliation(s)
- John P Aggleton
- School of Psychology, Cardiff University, Cardiff, Wales, UK
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Moreno A. Molecular mechanisms of forgetting. Eur J Neurosci 2020; 54:6912-6932. [DOI: 10.1111/ejn.14839] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 04/23/2020] [Accepted: 05/18/2020] [Indexed: 11/30/2022]
Affiliation(s)
- Andrea Moreno
- Danish Institute of Translational Neuroscience (DANDRITE) Aarhus University Aarhus C Denmark
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