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Yelhekar TD, Meng M, Doupe J, Lin Y. All IEGs Are Not Created Equal-Molecular Sorting Within the Memory Engram. ADVANCES IN NEUROBIOLOGY 2024; 38:81-109. [PMID: 39008012 DOI: 10.1007/978-3-031-62983-9_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
When neurons are recruited to form the memory engram, they are driven to activate the expression of a series of immediate-early genes (IEGs). While these IEGs have been used relatively indiscriminately to identify the so-called engram neurons, recent research has demonstrated that different IEG ensembles can be physically and functionally distinct within the memory engram. This inherent heterogeneity of the memory engram is driven by the diversity in the functions and distributions of different IEGs. This process, which we call molecular sorting, is analogous to sorting the entire population of engram neurons into different sub-engrams molecularly defined by different IEGs. In this chapter, we will describe the molecular sorting process by systematically reviewing published work on engram ensemble cells defined by the following four major IEGs: Fos, Npas4, Arc, and Egr1. By comparing and contrasting these likely different components of the memory engram, we hope to gain a better understanding of the logic and significance behind the molecular sorting process for memory functions.
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Affiliation(s)
- Tushar D Yelhekar
- Department of Psychiatry, O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Meizhen Meng
- Department of Psychiatry, O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Neuroscience Graduate Program, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joslyn Doupe
- Neuroscience Graduate Program, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Yingxi Lin
- Department of Psychiatry, O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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2
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Brosens N, Lesuis SL, Rao-Ruiz P, van den Oever MC, Krugers HJ. Shaping Memories Via Stress: A Synaptic Engram Perspective. Biol Psychiatry 2023:S0006-3223(23)01720-1. [PMID: 37977215 DOI: 10.1016/j.biopsych.2023.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 10/09/2023] [Accepted: 11/05/2023] [Indexed: 11/19/2023]
Abstract
Stress modulates the activity of various memory systems and can thereby guide behavioral interaction with the environment in an adaptive or maladaptive manner. At the cellular level, a large body of evidence indicates that (nor)adrenaline and glucocorticoid release induced by acute stress exposure affects synapse function and synaptic plasticity, which are critical substrates for learning and memory. Recent evidence suggests that memories are supported in the brain by sparsely distributed neurons within networks, termed engram cell ensembles. While the physiological and molecular effects of stress on the synapse are increasingly well characterized, how these synaptic modifications shape the multiscale dynamics of engram cell ensembles is still poorly understood. In this review, we discuss and integrate recent information on how acute stress affects synapse function and how this may alter engram cell ensembles and their synaptic connectivity to shape memory strength and memory precision. We provide a mechanistic framework of a synaptic engram under stress and put forward outstanding questions that address knowledge gaps in our understanding of the mechanisms that underlie stress-induced memory modulation.
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Affiliation(s)
- Niek Brosens
- Brain Plasticity Group, Swammerdam Institute for Life Sciences-Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands.
| | - Sylvie L Lesuis
- Brain Plasticity Group, Swammerdam Institute for Life Sciences-Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands; Cellular and Cognitive Neuroscience group, Swammerdam Institute for Life Sciences-Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands
| | - Priyanka Rao-Ruiz
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Michel C van den Oever
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Harm J Krugers
- Brain Plasticity Group, Swammerdam Institute for Life Sciences-Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands.
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3
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Berndt M, Trusel M, Roberts TF, Pfeiffer BE, Volk LJ. Bidirectional synaptic changes in deep and superficial hippocampal neurons following in vivo activity. Neuron 2023; 111:2984-2994.e4. [PMID: 37689058 PMCID: PMC10958998 DOI: 10.1016/j.neuron.2023.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 07/06/2023] [Accepted: 08/15/2023] [Indexed: 09/11/2023]
Abstract
Neuronal activity during experience is thought to induce plastic changes within the hippocampal network that underlie memory formation, although the extent and details of such changes in vivo remain unclear. Here, we employed a temporally precise marker of neuronal activity, CaMPARI2, to label active CA1 hippocampal neurons in vivo, followed by immediate acute slice preparation and electrophysiological quantification of synaptic properties. Recently active neurons in the superficial sublayer of stratum pyramidale displayed larger post-synaptic responses at excitatory synapses from area CA3, with no change in pre-synaptic release probability. In contrast, in vivo activity correlated with weaker pre- and post-synaptic excitatory weights onto pyramidal cells in the deep sublayer. In vivo activity of deep and superficial neurons within sharp-wave/ripples was bidirectionally changed across experience, consistent with the observed changes in synaptic weights. These findings reveal novel, fundamental mechanisms through which the hippocampal network is modified by experience to store information.
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Affiliation(s)
- Marcus Berndt
- UT Southwestern Medical Center Neuroscience Graduate Program, Dallas, TX 75390, USA; UT Southwestern Medical Center Department of Neuroscience, Dallas, TX 75390, USA
| | - Massimo Trusel
- UT Southwestern Medical Center Department of Neuroscience, Dallas, TX 75390, USA
| | - Todd F Roberts
- UT Southwestern Medical Center Neuroscience Graduate Program, Dallas, TX 75390, USA; UT Southwestern Medical Center Department of Neuroscience, Dallas, TX 75390, USA; Peter O'Donnell Brain Institute, Dallas, TX 75390, USA
| | - Brad E Pfeiffer
- UT Southwestern Medical Center Neuroscience Graduate Program, Dallas, TX 75390, USA; UT Southwestern Medical Center Department of Neuroscience, Dallas, TX 75390, USA; Peter O'Donnell Brain Institute, Dallas, TX 75390, USA.
| | - Lenora J Volk
- UT Southwestern Medical Center Neuroscience Graduate Program, Dallas, TX 75390, USA; UT Southwestern Medical Center Department of Neuroscience, Dallas, TX 75390, USA; UT Southwestern Medical Center Department of Psychiatry, Dallas, TX 75390, USA; Peter O'Donnell Brain Institute, Dallas, TX 75390, USA.
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4
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Murthy BKB, Somatakis S, Ulivi AF, Klimmt H, Castello-Waldow TP, Haynes N, Huettl RE, Chen A, Attardo A. Arc-driven mGRASP highlights CA1 to CA3 synaptic engrams. Front Behav Neurosci 2023; 16:1072571. [PMID: 36793796 PMCID: PMC9924068 DOI: 10.3389/fnbeh.2022.1072571] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/29/2022] [Indexed: 02/03/2023] Open
Abstract
Subpopulations of neurons display increased activity during memory encoding and manipulating the activity of these neurons can induce artificial formation or erasure of memories. Thus, these neurons are thought to be cellular engrams. Moreover, correlated activity between pre- and postsynaptic engram neurons is thought to lead to strengthening of their synaptic connections, thus increasing the probability of neural activity patterns occurring during encoding to reoccur at recall. Therefore, synapses between engram neurons can also be considered as a substrate of memory, or a synaptic engram. One can label synaptic engrams by targeting two complementary, non-fluorescent, synapse-targeted GFP fragments separately to the pre- and postsynaptic compartment of engram neurons; the two GFP fragments reconstitute a fluorescent GFP at the synaptic cleft between the engram neurons, thereby highlighting synaptic engrams. In this work we explored a transsynaptic GFP reconstitution system (mGRASP) to label synaptic engrams between hippocampal CA1 and CA3 engram neurons identified by different Immediate-Early Genes: cFos and Arc. We characterized the expression of the cellular and synaptic labels of the mGRASP system upon exposure to a novel environment or learning of a hippocampal-dependent memory task. We found that mGRASP under the control of transgenic ArcCreERT2 labeled synaptic engrams more efficiently than when controlled by viral cFostTA, possibly due to differences in the genetic systems rather than the specific IEG promoters.
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Affiliation(s)
- B. K. B. Murthy
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany
| | - S. Somatakis
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A. F. Ulivi
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Max Planck Institute of Psychiatry, Munich, Germany
| | - H. Klimmt
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany
| | | | - N. Haynes
- Max Planck Institute of Psychiatry, Munich, Germany
| | - R. E. Huettl
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A. Chen
- Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany,Weizmann Institute of Science, Rehovot, Israel
| | - Alessio Attardo
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany,*Correspondence: Alessio Attardo,
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5
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Chenani A, Weston G, Ulivi AF, Castello-Waldow TP, Huettl RE, Chen A, Attardo A. Repeated stress exposure leads to structural synaptic instability prior to disorganization of hippocampal coding and impairments in learning. Transl Psychiatry 2022; 12:381. [PMID: 36096987 PMCID: PMC9468341 DOI: 10.1038/s41398-022-02107-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/15/2022] [Accepted: 08/05/2022] [Indexed: 12/30/2022] Open
Abstract
Stress exposure impairs brain structure and function, resulting in cognitive deficits and increased risk for psychiatric disorders such as depression, schizophrenia, anxiety and post-traumatic stress disorder. In particular, stress exposure affects function and structure of hippocampal CA1 leading to impairments in episodic memory. Here, we applied longitudinal deep-brain optical imaging to investigate the link between changes in activity patterns and structural plasticity of dorsal CA1 pyramidal neurons and hippocampal-dependent learning and memory in mice exposed to stress. We found that several days of repeated stress led to a substantial increase in neuronal activity followed by disruption of the temporal structure of this activity and spatial coding. We then tracked dynamics of structural excitatory connectivity as a potential underlying cause of the changes in activity induced by repeated stress. We thus discovered that exposure to repeated stress leads to an immediate decrease in spinogenesis followed by decrease in spine stability. By comparison, acute stress led to stabilization of the spines born in temporal proximity to the stressful event. Importantly, the temporal relationship between changes in activity levels, structural connectivity and activity patterns, suggests that loss of structural connectivity mediates the transition between increased activity and impairment of temporal organization and spatial information content in dorsal CA1 upon repeated stress exposure.
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Affiliation(s)
| | - Ghabiba Weston
- Max Planck Institute of Psychiatry, 80804, Munich, Germany
- Graduate School of Systemic Neurosciences GSN-LMU, 82152, Munich, Germany
| | - Alessandro F Ulivi
- Max Planck Institute of Psychiatry, 80804, Munich, Germany
- Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany
| | | | | | - Alon Chen
- Max Planck Institute of Psychiatry, 80804, Munich, Germany
- Graduate School of Systemic Neurosciences GSN-LMU, 82152, Munich, Germany
- Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Alessio Attardo
- Max Planck Institute of Psychiatry, 80804, Munich, Germany.
- Graduate School of Systemic Neurosciences GSN-LMU, 82152, Munich, Germany.
- Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany.
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6
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Redman WT, Wolcott NS, Montelisciani L, Luna G, Marks TD, Sit KK, Yu CH, Smith S, Goard MJ. Long-term transverse imaging of the hippocampus with glass microperiscopes. eLife 2022; 11:75391. [PMID: 35775393 PMCID: PMC9249394 DOI: 10.7554/elife.75391] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 06/12/2022] [Indexed: 11/19/2022] Open
Abstract
The hippocampus consists of a stereotyped neuronal circuit repeated along the septal-temporal axis. This transverse circuit contains distinct subfields with stereotyped connectivity that support crucial cognitive processes, including episodic and spatial memory. However, comprehensive measurements across the transverse hippocampal circuit in vivo are intractable with existing techniques. Here, we developed an approach for two-photon imaging of the transverse hippocampal plane in awake mice via implanted glass microperiscopes, allowing optical access to the major hippocampal subfields and to the dendritic arbor of pyramidal neurons. Using this approach, we tracked dendritic morphological dynamics on CA1 apical dendrites and characterized spine turnover. We then used calcium imaging to quantify the prevalence of place and speed cells across subfields. Finally, we measured the anatomical distribution of spatial information, finding a non-uniform distribution of spatial selectivity along the DG-to-CA1 axis. This approach extends the existing toolbox for structural and functional measurements of hippocampal circuitry.
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Affiliation(s)
- William T Redman
- Interdepartmental Graduate Program in Dynamical Neuroscience, University of California, Santa Barbara, United States
| | - Nora S Wolcott
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, United States
| | - Luca Montelisciani
- Cognitive and Systems Neuroscience Group, University of Amsterdam, Amsterdam, Netherlands
| | - Gabriel Luna
- Neuroscience Research Institute, University of California, Santa Barbara, United States
| | - Tyler D Marks
- Neuroscience Research Institute, University of California, Santa Barbara, United States
| | - Kevin K Sit
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, United States
| | - Che-Hang Yu
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, United States
| | - Spencer Smith
- Neuroscience Research Institute, University of California, Santa Barbara, United States.,Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, United States
| | - Michael J Goard
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, United States.,Neuroscience Research Institute, University of California, Santa Barbara, United States.,Department of Psychological and Brain Sciences, University of California, Santa Barbara, United States
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7
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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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8
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Gonzalez KC, Losonczy A, Negrean A. Dendritic Excitability and Synaptic Plasticity In Vitro and In Vivo. Neuroscience 2022; 489:165-175. [PMID: 34998890 PMCID: PMC9392867 DOI: 10.1016/j.neuroscience.2021.12.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 02/06/2023]
Abstract
Much of our understanding of dendritic and synaptic physiology comes from in vitro experimentation, where the afforded mechanical stability and convenience of applying drugs allowed patch-clamping based recording techniques to investigate ion channel distributions, their gating kinetics, and to uncover dendritic integrative and synaptic plasticity rules. However, with current efforts to study these questions in vivo, there is a great need to translate existing knowledge between in vitro and in vivo experimental conditions. In this review, we identify discrepancies between in vitro and in vivo ionic composition of extracellular media and discuss how changes in ionic composition alter dendritic excitability and plasticity induction. Here, we argue that under physiological in vivo ionic conditions, dendrites are expected to be more excitable and the threshold for synaptic plasticity induction to be lowered. Consequently, the plasticity rules described in vitro vary significantly from those implemented in vivo.
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Affiliation(s)
- Kevin C Gonzalez
- Department of Neuroscience, Columbia University, New York, NY, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, New York, NY, USA.
| | - Attila Losonczy
- Department of Neuroscience, Columbia University, New York, NY, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, New York, NY, USA; Kavli Institute for Brain Science, New York, NY, USA.
| | - Adrian Negrean
- Department of Neuroscience, Columbia University, New York, NY, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, New York, NY, USA.
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9
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Sità L, Brondi M, Lagomarsino de Leon Roig P, Curreli S, Panniello M, Vecchia D, Fellin T. A deep-learning approach for online cell identification and trace extraction in functional two-photon calcium imaging. Nat Commun 2022; 13:1529. [PMID: 35318335 PMCID: PMC8940911 DOI: 10.1038/s41467-022-29180-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/24/2022] [Indexed: 12/11/2022] Open
Abstract
In vivo two-photon calcium imaging is a powerful approach in neuroscience. However, processing two-photon calcium imaging data is computationally intensive and time-consuming, making online frame-by-frame analysis challenging. This is especially true for large field-of-view (FOV) imaging. Here, we present CITE-On (Cell Identification and Trace Extraction Online), a convolutional neural network-based algorithm for fast automatic cell identification, segmentation, identity tracking, and trace extraction in two-photon calcium imaging data. CITE-On processes thousands of cells online, including during mesoscopic two-photon imaging, and extracts functional measurements from most neurons in the FOV. Applied to publicly available datasets, the offline version of CITE-On achieves performance similar to that of state-of-the-art methods for offline analysis. Moreover, CITE-On generalizes across calcium indicators, brain regions, and acquisition parameters in anesthetized and awake head-fixed mice. CITE-On represents a powerful tool to speed up image analysis and facilitate closed-loop approaches, for example in combined all-optical imaging and manipulation experiments.
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Affiliation(s)
- Luca Sità
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy.
| | - Marco Brondi
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy.
| | - Pedro Lagomarsino de Leon Roig
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- University of Genova, Genova, Italy
| | - Sebastiano Curreli
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Mariangela Panniello
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Dania Vecchia
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy.
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10
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Zieglgänsberger W, Brenneisen R, Berthele A, Wotjak CT, Bandelow B, Tölle TR, Lutz B. Chronic Pain and the Endocannabinoid System: Smart Lipids - A Novel Therapeutic Option? Med Cannabis Cannabinoids 2022; 5:61-75. [PMID: 35702403 PMCID: PMC9149512 DOI: 10.1159/000522432] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 01/21/2022] [Indexed: 08/05/2023] Open
Abstract
The development of a high-end cannabinoid-based therapy is the result of intense translational research, aiming to convert recent discoveries in the laboratory into better treatments for patients. Novel compounds and new regimes for drug treatment are emerging. Given that previously unreported signaling mechanisms for cannabinoids have been uncovered, clinical studies detailing their high therapeutic potential are mandatory. The advent of novel genomic, optogenetic, and viral tracing and imaging techniques will help to further detail therapeutically relevant functional and structural features. An evolutionarily highly conserved group of neuromodulatory lipids, their receptors, and anabolic and catabolic enzymes are involved in a remarkable variety of physiological and pathological processes and has been termed the endocannabinoid system (ECS). A large body of data has emerged in recent years, pointing to a crucial role of this system in the regulation of the behavioral domains of acquired fear, anxiety, and stress-coping. Besides neurons, also glia cells and components of the immune system can differentially fine-tune patterns of neuronal activity. Dysregulation of ECS signaling can lead to a lowering of stress resilience and increased incidence of psychiatric disorders. Chronic pain may be understood as a disease process evoked by fear-conditioned nociceptive input and appears as the dark side of neuronal plasticity. By taking a toll on every part of your life, this abnormal persistent memory of an aversive state can be more damaging than its initial experience. All strategies for the treatment of chronic pain conditions must consider stress-related comorbid conditions since cognitive factors such as beliefs, expectations, and prior experience (memory of pain) are key modulators of the perception of pain. The anxiolytic and anti-stress effects of medical cannabinoids can substantially modulate the efficacy and tolerability of therapeutic interventions and will help to pave the way to a successful multimodal therapy. Why some individuals are more susceptible to the effects of stress remains to be uncovered. The development of personalized prevention or treatment strategies for anxiety and depression related to chronic pain must also consider gender differences. An emotional basis of chronic pain opens a new horizon of opportunities for developing treatment strategies beyond the repeated sole use of acutely acting analgesics. A phase I trial to determine the pharmacokinetics, psychotropic effects, and safety profile of a novel nanoparticle-based cannabinoid spray for oromucosal delivery highlights a remarkable innovation in galenic technology and urges clinical studies further detailing the huge therapeutic potential of medical cannabis (Lorenzl et al.; this issue).
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Affiliation(s)
| | | | | | | | - Borwin Bandelow
- Department of Psychiatry and Psychotherapy, University Medical Center, Göttingen, Germany
| | | | - Beat Lutz
- Institute of Physiological Chemistry, University Medical Center Mainz, Mainz, Germany
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11
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Gros A, Lim AWH, Hohendorf V, White N, Eckert M, McHugh TJ, Wang SH. Behavioral and Cellular Tagging in Young and in Early Cognitive Aging. Front Aging Neurosci 2022; 14:809879. [PMID: 35283750 PMCID: PMC8907879 DOI: 10.3389/fnagi.2022.809879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 01/06/2022] [Indexed: 11/17/2022] Open
Abstract
The ability to maintain relevant information on a daily basis is negatively impacted by aging. However, the neuronal mechanism manifesting memory persistence in young animals and memory decline in early aging is not fully understood. A novel event, when introduced around encoding of an everyday memory task, can facilitate memory persistence in young age but not in early aging. Here, we investigated in male rats how sub-regions of the hippocampus are involved in memory representation in behavioral tagging and how early aging affects such representation by combining behavioral training in appetitive delayed-matching-to-place tasks with the “cellular compartment analysis of temporal activity by fluorescence in situ hybridization” technique. We show that neuronal assemblies activated by memory encoding were also partially activated by novelty, particularly in the distal CA1 and proximal CA3 subregions in young male rats. In early aging, both encoding- and novelty-triggered neuronal populations were significantly reduced with a more profound effect in encoding neurons. Thus, memory persistence through novelty facilitation engages overlapping hippocampal assemblies as a key cellular signature, and cognitive aging is associated with underlying reduction in neuronal activation.
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Affiliation(s)
- Alexandra Gros
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Amos W. H. Lim
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Victoria Hohendorf
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Nicole White
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Michael Eckert
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - Thomas John McHugh
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Saitama, Japan
| | - Szu-Han Wang
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
- *Correspondence: Szu-Han Wang,
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12
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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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Wu W, Cao X, Wang Y. The role of miRNA-624-5p in congenital hypothyroidism and its molecular mechanism by targeting SIRT1. Genes Genomics 2021; 44:1137-1147. [PMID: 34609722 DOI: 10.1007/s13258-021-01171-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 09/23/2021] [Indexed: 11/25/2022]
Abstract
BACKGROUND Accumulating reports evidenced that congenital hypothyroidism (CH) is a kind of endocrine diseases caused by thyroid hormone imperfection. MicroRNAs (miRNAs) were confirmed to exhibit protective functions in CH progression. However, the functions and latent mechanism of microRNA-624-5p (miR-624-5p) in CH remains unknown. OBJECTIVE This report was designed to illustrate the potential molecular mechanisms of miR-624-5p on CH. METHODS Rats were induced by 50 mg/day propylthiouracil to conduct CH models. Free thyroxine (fT4) and thyroid-Stimulating hormone (TSH) concentrations were measured to confirm CH model conduction. The direct target of miR-624-5p was predicted and verified by Starbase and dual luciferase reporter assay. Besides, the levels of miR-624-5p and sirtuin1 (SIRT1) in hippocampus or hippocampal neuronal cells were assessed using quantitative real-time polymerase chain reaction (qRT-PCR) or Western blot assays. Then CH rat behaviors were evaluated using open field test (OFT) and forced swim test (FST). Furthermore, neuronal cells viability and apoptosis were checked using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and flow cytometry. RESULTS qRT-PCR assay suggested that miR-624-5p was up-regulated and SIRT1 was low-expressed in hippocampus tissues of CH rats. SIRT1 was a direct target of miR-624-5p. MiR-624-5p inhibitor signally enhanced fT4 levels and reduced TSH levels in the plasma of CH rats, and improved CH rat depressive behaviors by targeting SIRT1. Moreover, our data also revealed that miR-624-5p inhibitor increased cell viability and reduced apoptotic neuronal cells, which was reversed by silencing of SIRT1. CONCLUSIONS Taken together, this research demonstrated that miR-624-5p serves as a promising target for CH treatment.
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Affiliation(s)
- Wanli Wu
- Department of Pediatrics, Yiwu Maternity and Children Hospital, No. C100 Xinke Road, Yiwu, 322000, China
| | - Xuying Cao
- Department of Pediatrics, Yiwu Maternity and Children Hospital, No. C100 Xinke Road, Yiwu, 322000, China
| | - Yuhong Wang
- Department of Pediatrics, Yiwu Maternity and Children Hospital, No. C100 Xinke Road, Yiwu, 322000, China.
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Ko SY, Frankland PW. Neurogenesis-dependent transformation of hippocampal engrams. Neurosci Lett 2021; 762:136176. [PMID: 34400284 DOI: 10.1016/j.neulet.2021.136176] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/29/2021] [Accepted: 08/11/2021] [Indexed: 11/29/2022]
Abstract
In humans and other mammals, memories of events are encoded by neuronal ensembles (or engrams) in the hippocampus. The mnemonic information stored in these engrams can then be used to guide future behavior, including prediction- and decision-making in dynamic environments. While some hippocampal engrams may be persistently stored, others are modified over time, suggesting that the represented memories may also be transformed. How might hippocampal engrams be modified through time? Adult hippocampal neurogenesis represents one process that continuously rewires hippocampal circuitry, presumably including stored hippocampal engrams. At intermediate stages, we propose that neurogenesis-mediated rewiring of hippocampal engram circuitry induces forgetting of specific stimulus attributes, and this less precise engram allows for generalization. At more advanced stages, we propose that neurogenesis-mediated rewiring of hippocampal engram circuitry leads to silencing of hippocampal engrams, rendering them no longer accessible by natural retrieval cues.
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Affiliation(s)
- Sangyoon Y Ko
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Temerty Centre for AI Research and Education in Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Paul W Frankland
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5S 3G3, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada; Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1, Canada.
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Ryan TJ, Ortega-de San Luis C, Pezzoli M, Sen S. Engram cell connectivity: an evolving substrate for information storage. Curr Opin Neurobiol 2021; 67:215-225. [PMID: 33812274 DOI: 10.1016/j.conb.2021.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/15/2021] [Accepted: 01/16/2021] [Indexed: 01/02/2023]
Abstract
Understanding memory requires an explanation for how information can be stored in the brain in a stable state. The change in the brain that accounts for a given memory is referred to as an engram. In recent years, the term engram has been operationalized as the cells that are activated by a learning experience, undergoes plasticity, and are sufficient and necessary for memory recall. Using this framework, and a growing toolbox of related experimental techniques, engram manipulation has become a central topic in behavioral, systems, and molecular neuroscience. Recent research on the topic has provided novel insights into the mechanisms of long-term memory storage, and its overlap with instinct. We propose that memory and instinct may be embodied as isomorphic topological structures within the brain's microanatomical circuitry.
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Affiliation(s)
- Tomás J Ryan
- School of Biochemistry and Immunology and Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland; Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3052, Australia; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1M1, Canada.
| | - Clara Ortega-de San Luis
- School of Biochemistry and Immunology and Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Maurizio Pezzoli
- School of Biochemistry and Immunology and Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Siddhartha Sen
- Centre for Research on Adaptive Nanostructures and Nanodevices and School of Physics, Trinity College Dublin, D02 PN40, Ireland
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Mau W, Hasselmo ME, Cai DJ. The brain in motion: How ensemble fluidity drives memory-updating and flexibility. eLife 2020; 9:e63550. [PMID: 33372892 PMCID: PMC7771967 DOI: 10.7554/elife.63550] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/12/2020] [Indexed: 12/18/2022] Open
Abstract
While memories are often thought of as flashbacks to a previous experience, they do not simply conserve veridical representations of the past but must continually integrate new information to ensure survival in dynamic environments. Therefore, 'drift' in neural firing patterns, typically construed as disruptive 'instability' or an undesirable consequence of noise, may actually be useful for updating memories. In our view, continual modifications in memory representations reconcile classical theories of stable memory traces with neural drift. Here we review how memory representations are updated through dynamic recruitment of neuronal ensembles on the basis of excitability and functional connectivity at the time of learning. Overall, we emphasize the importance of considering memories not as static entities, but instead as flexible network states that reactivate and evolve across time and experience.
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Affiliation(s)
- William Mau
- Neuroscience Department, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | | | - Denise J Cai
- Neuroscience Department, Icahn School of Medicine at Mount SinaiNew YorkUnited States
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