1
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Ingram R, Volianskis A. Promiscuous involvement of metabotropic glutamate receptors in the storage of N-methyl-d-aspartate receptor-dependent short-term potentiation. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230445. [PMID: 38853548 DOI: 10.1098/rstb.2023.0445] [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: 01/14/2024] [Accepted: 04/04/2024] [Indexed: 06/11/2024] Open
Abstract
Short- and long-term forms of N-methyl-d-aspartate receptor (NMDAR)-dependent potentiation (most commonly termed short-term potentiation (STP) and long-term potentiation (LTP)) are co-induced in hippocampal slices by theta-burst stimulation, which mimics naturally occurring patterns of neuronal activity. While NMDAR-dependent LTP (NMDAR-LTP) is said to be the cellular correlate of long-term memory storage, NMDAR-dependent STP (NMDAR-STP) is thought to underlie the encoding of shorter-lasting memories. The mechanisms of NMDAR-LTP have been researched much more extensively than those of NMDAR-STP, which is characterized by its extreme stimulation dependence. Thus, in the absence of low-frequency test stimulation, which is used to test the magnitude of potentiation, NMDAR-STP does not decline until the stimulation is resumed. NMDAR-STP represents, therefore, an inverse variant of Hebbian synaptic plasticity, illustrating that inactive synapses can retain their strength unchanged until they become active again. The mechanisms, by which NMDAR-STP is stored in synapses without a decrement, are unknown and we report here that activation of metabotropic glutamate receptors may be critical in maintaining the potentiated state of synaptic transmission. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Rachael Ingram
- Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London , London E1 2AT, UK
| | - Arturas Volianskis
- Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London , London E1 2AT, UK
- School of Biosciences, Cardiff University, Museum Avenue , Cardiff CF10 3AX, UK
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2
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Rice CA, Stackman RW. The small conductance Ca 2+-activated K + channel activator GW542573X impairs hippocampal memory in C57BL/6J mice. Neuropharmacology 2024; 252:109960. [PMID: 38631563 DOI: 10.1016/j.neuropharm.2024.109960] [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: 01/30/2024] [Revised: 03/22/2024] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
Small conductance Ca2+-activated K+ (SK) channels, expressed throughout the CNS, are comprised of SK1, SK2 and SK3 subunits, assembled as homotetrameric or heterotetrameric proteins. SK channels expressed somatically modulate the excitability of neurons by mediating the medium component of the afterhyperpolarization. Synaptic SK channels shape excitatory postsynaptic potentials and synaptic plasticity. Such SK-mediated effects on neuronal excitability and activity-dependent synaptic strength likely underlie the modulatory influence of SK channels on memory encoding. Converging evidence indicates that several forms of long-term memory are facilitated by administration of the SK channel blocker, apamin, and impaired by administration of the pan-SK channel activator, 1-EBIO, or by overexpression of the SK2 subunit. The selective knockdown of dendritic SK2 subunits facilitates memory to a similar extent as that observed after systemic apamin. SK1 subunits co-assemble with SK2; yet the functional significance of SK1 has not been clearly defined. Here, we examined the effects of GW542573X, a drug that activates SK1 containing SK channels, as well as SK2/3, on several forms of long-term memory in male C57BL/6J mice. Our results indicate that pre-training, but not post-training, systemic GW542573X impaired object memory and fear memory in mice tested 24 h after training. Pre-training direct bilateral infusion of GW542573X into the CA1 of hippocampus impaired object memory encoding. These data suggest that systemic GW542573X impairs long-term memory. These results add to growing evidence that SK2 subunit-, and SK1 subunit-, containing SK channels can regulate behaviorally triggered synaptic plasticity necessary for encoding hippocampal-dependent memory.
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Affiliation(s)
- Claire A Rice
- Department of Psychology, Jupiter Life Science Initiative and the Stiles-Nicholson Brain Institute, Florida Atlantic University, 5353 Parkside Drive, Jupiter, FL, 33458, USA
| | - Robert W Stackman
- Department of Psychology, Jupiter Life Science Initiative and the Stiles-Nicholson Brain Institute, Florida Atlantic University, 5353 Parkside Drive, Jupiter, FL, 33458, USA.
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3
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Iacobucci GJ, Popescu GK. Calcium- and calmodulin-dependent inhibition of NMDA receptor currents. Biophys J 2024; 123:277-293. [PMID: 38140727 PMCID: PMC10870176 DOI: 10.1016/j.bpj.2023.12.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/05/2023] [Accepted: 12/19/2023] [Indexed: 12/24/2023] Open
Abstract
Calcium ions (Ca2+) reduce NMDA receptor currents through several distinct mechanisms. Among these, calmodulin (CaM)-dependent inhibition (CDI) accomplishes rapid, reversible, and incomplete reduction of the NMDA receptor currents in response to elevations in intracellular Ca2+. Quantitative and mechanistic descriptions of CDI of NMDA receptor-mediated signals have been marred by variability originating, in part, from differences in the conditions and metrics used to evaluate this process across laboratories. Recent ratiometric approaches to measure the magnitude and kinetics of NMDA receptor CDI have facilitated rapid insights into this phenomenon. Notably, the kinetics and magnitude of NMDA receptor CDI depend on the degree of saturation of its CaM binding sites, which represent the bona fide calcium sensor for this type of inhibition, the kinetics and magnitude of the Ca2+ signal, which depends on the biophysical properties of the NMDA receptor or of adjacent Ca2+ sources, and on the relative distribution of Ca2+ sources and CaM molecules. Given that all these factors vary widely during development, across cell types, and with physiological and pathological states, it is important to understand how NMDA receptor CDI develops and how it contributes to signaling in the central nervous system. Here, we review briefly these recent advances and highlight remaining questions about the structural and kinetic mechanisms of NMDA receptor CDI. Given that pathologies can arise from several sources, including mutations in the NMDA receptor and in CaM, understanding how CaM responds to intracellular Ca2+ signals to initiate conformational changes in NMDA receptors, and mapping the structural domains responsible will help to envision novel therapeutic strategies to neuropsychiatric diseases, which presently have limited available treatments.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York.
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4
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Pham T, Hussein T, Calis D, Bischof H, Skrabak D, Cruz Santos M, Maier S, Spähn D, Kalina D, Simonsig S, Ehinger R, Groschup B, Knipper M, Plesnila N, Ruth P, Lukowski R, Matt L. BK channels sustain neuronal Ca 2+ oscillations to support hippocampal long-term potentiation and memory formation. Cell Mol Life Sci 2023; 80:369. [PMID: 37989805 PMCID: PMC10663188 DOI: 10.1007/s00018-023-05016-y] [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: 05/15/2023] [Revised: 09/25/2023] [Accepted: 10/24/2023] [Indexed: 11/23/2023]
Abstract
Mutations of large conductance Ca2+- and voltage-activated K+ channels (BK) are associated with cognitive impairment. Here we report that CA1 pyramidal neuron-specific conditional BK knock-out (cKO) mice display normal locomotor and anxiety behavior. They do, however, exhibit impaired memory acquisition and retrieval in the Morris Water Maze (MWM) when compared to littermate controls (CTRL). In line with cognitive impairment in vivo, electrical and chemical long-term potentiation (LTP) in cKO brain slices were impaired in vitro. We further used a genetically encoded fluorescent K+ biosensor and a Ca2+-sensitive probe to observe cultured hippocampal neurons during chemical LTP (cLTP) induction. cLTP massively reduced intracellular K+ concentration ([K+]i) while elevating L-Type Ca2+ channel- and NMDA receptor-dependent Ca2+ oscillation frequencies. Both, [K+]i decrease and Ca2+ oscillation frequency increase were absent after pharmacological BK inhibition or in cells lacking BK. Our data suggest that L-Type- and NMDAR-dependent BK-mediated K+ outflow significantly contributes to hippocampal LTP, as well as learning and memory.
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Affiliation(s)
- Thomas Pham
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Tamara Hussein
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Dila Calis
- Department of Otolaryngology, Head and Neck Surgery, Molecular Physiology of Hearing, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Helmut Bischof
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - David Skrabak
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Melanie Cruz Santos
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Selina Maier
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - David Spähn
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Daniel Kalina
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Stefanie Simonsig
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Rebekka Ehinger
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Bernhard Groschup
- Laboratory of Experimental Stroke Research, Institute for Stroke and Dementia Research (ISD), University Hospital, Ludwig-Maximilians-University Munich (LMU), Munich, Germany
| | - Marlies Knipper
- Department of Otolaryngology, Head and Neck Surgery, Molecular Physiology of Hearing, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Nikolaus Plesnila
- Laboratory of Experimental Stroke Research, Institute for Stroke and Dementia Research (ISD), University Hospital, Ludwig-Maximilians-University Munich (LMU), Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Lucas Matt
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany.
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5
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O'Donnell C. Nonlinear slow-timescale mechanisms in synaptic plasticity. Curr Opin Neurobiol 2023; 82:102778. [PMID: 37657186 DOI: 10.1016/j.conb.2023.102778] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 09/03/2023]
Abstract
Learning and memory rely on synapses changing their strengths in response to neural activity. However, there is a substantial gap between the timescales of neural electrical dynamics (1-100 ms) and organism behaviour during learning (seconds-minutes). What mechanisms bridge this timescale gap? What are the implications for theories of brain learning? Here I first cover experimental evidence for slow-timescale factors in plasticity induction. Then I review possible underlying cellular and synaptic mechanisms, and insights from recent computational models that incorporate such slow-timescale variables. I conclude that future progress in understanding brain learning across timescales will require both experimental and computational modelling studies that map out the nonlinearities implemented by both fast and slow plasticity mechanisms at synapses, and crucially, their joint interactions.
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Affiliation(s)
- Cian O'Donnell
- School of Computing, Engineering, and Intelligent Systems, Magee Campus, Ulster University, Derry/Londonderry, UK; School of Computer Science, Electrical and Electronic Engineering, and Engineering Maths, University of Bristol, Bristol, UK.
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6
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Rodrigues YE, Tigaret CM, Marie H, O'Donnell C, Veltz R. A stochastic model of hippocampal synaptic plasticity with geometrical readout of enzyme dynamics. eLife 2023; 12:e80152. [PMID: 37589251 PMCID: PMC10435238 DOI: 10.7554/elife.80152] [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: 05/10/2022] [Accepted: 03/22/2023] [Indexed: 08/18/2023] Open
Abstract
Discovering the rules of synaptic plasticity is an important step for understanding brain learning. Existing plasticity models are either (1) top-down and interpretable, but not flexible enough to account for experimental data, or (2) bottom-up and biologically realistic, but too intricate to interpret and hard to fit to data. To avoid the shortcomings of these approaches, we present a new plasticity rule based on a geometrical readout mechanism that flexibly maps synaptic enzyme dynamics to predict plasticity outcomes. We apply this readout to a multi-timescale model of hippocampal synaptic plasticity induction that includes electrical dynamics, calcium, CaMKII and calcineurin, and accurate representation of intrinsic noise sources. Using a single set of model parameters, we demonstrate the robustness of this plasticity rule by reproducing nine published ex vivo experiments covering various spike-timing and frequency-dependent plasticity induction protocols, animal ages, and experimental conditions. Our model also predicts that in vivo-like spike timing irregularity strongly shapes plasticity outcome. This geometrical readout modelling approach can be readily applied to other excitatory or inhibitory synapses to discover their synaptic plasticity rules.
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Affiliation(s)
- Yuri Elias Rodrigues
- Université Côte d’AzurNiceFrance
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRSValbonneFrance
- Inria Center of University Côte d’Azur (Inria)Sophia AntipolisFrance
| | - Cezar M Tigaret
- Neuroscience and Mental Health Research Innovation Institute, Division of Psychological Medicine and Clinical Neurosciences,School of Medicine, Cardiff UniversityCardiffUnited Kingdom
| | - Hélène Marie
- Université Côte d’AzurNiceFrance
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRSValbonneFrance
| | - Cian O'Donnell
- School of Computing, Engineering, and Intelligent Systems, Magee Campus, Ulster UniversityLondonderryUnited Kingdom
- School of Computer Science, Electrical and Electronic Engineering, and Engineering Mathematics, University of BristolBristolUnited Kingdom
| | - Romain Veltz
- Inria Center of University Côte d’Azur (Inria)Sophia AntipolisFrance
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7
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Moldwin T, Kalmenson M, Segev I. Asymmetric Voltage Attenuation in Dendrites Can Enable Hierarchical Heterosynaptic Plasticity. eNeuro 2023; 10:ENEURO.0014-23.2023. [PMID: 37414554 PMCID: PMC10354808 DOI: 10.1523/eneuro.0014-23.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 05/16/2023] [Accepted: 06/14/2023] [Indexed: 07/08/2023] Open
Abstract
Long-term synaptic plasticity is mediated via cytosolic calcium concentrations ([Ca2+]). Using a synaptic model that implements calcium-based long-term plasticity via two sources of Ca2+ - NMDA receptors and voltage-gated calcium channels (VGCCs) - we show in dendritic cable simulations that the interplay between these two calcium sources can result in a diverse array of heterosynaptic effects. When spatially clustered synaptic input produces a local NMDA spike, the resulting dendritic depolarization can activate VGCCs at nonactivated spines, resulting in heterosynaptic plasticity. NMDA spike activation at a given dendritic location will tend to depolarize dendritic regions that are located distally to the input site more than dendritic sites that are proximal to it. This asymmetry can produce a hierarchical effect in branching dendrites, where an NMDA spike at a proximal branch can induce heterosynaptic plasticity primarily at branches that are distal to it. We also explored how simultaneously activated synaptic clusters located at different dendritic locations synergistically affect the plasticity at the active synapses, as well as the heterosynaptic plasticity of an inactive synapse "sandwiched" between them. We conclude that the inherent electrical asymmetry of dendritic trees enables sophisticated schemes for spatially targeted supervision of heterosynaptic plasticity.
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Affiliation(s)
| | - Menachem Kalmenson
- Department of Neurobiology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Idan Segev
- Edmond and Lily Safra Center for Brain Sciences
- Department of Neurobiology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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8
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Ferber SG, Weller A, Soreq H. Control systems theory revisited: new insights on the brain clocks of time-to-action. Front Neurosci 2023; 17:1171765. [PMID: 37378011 PMCID: PMC10292755 DOI: 10.3389/fnins.2023.1171765] [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: 02/22/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
To outline the complex biological rhythms underlying the time-to-action of goal-oriented behavior in the adult brain, we employed a Boolean Algebra model based on Control Systems Theory. This suggested that "timers" of the brain reflect a metabolic excitation-inhibition balance and that healthy clocks underlying goal-oriented behavior (optimal range of signal variability) are maintained by XOR logic gates in parallel sequences between cerebral levels. Using truth tables, we found that XOR logic gates reflect healthy, regulated time-to-action events between levels. We argue that the brain clocks of time-to-action are active within multileveled, parallel-sequence complexes shaped by experience. We show the metabolic components of time-to-action in levels ranging from the atom level through molecular, cellular, network and inter-regional levels, operating as parallel sequences. We employ a thermodynamic perspective, suggest that clock genes calculate free energy versus entropy and derived time-to-action level-wise as a master controller, and show that they are receivers, as well as transmitters of information. We argue that regulated multileveled time-to-action processes correspond to Boltzmann's thermodynamic theorem of micro- and macro-states, and that the available metabolic free-energy-entropy matrix determines the brain's reversible states for its age-appropriate chrono-properties at given moments. Thus, healthy timescales are not a precise number of nano- or milliseconds of activity nor a simple phenotypic distinction between slow vs. quick time-to-action, but rather encompass a range of variability, which depends on the molecules' size and dynamics with the composition of receptors, protein and RNA isoforms.
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Affiliation(s)
- Sari Goldstein Ferber
- Department of Psychology, Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
- Department of Psychology and Brain Sciences, University of Delaware, Newark, DE, United States
| | - Aron Weller
- Department of Psychology, Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Hermona Soreq
- The Edmond and Lily Safra Center for Brain Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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9
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Spike timing-dependent plasticity and memory. Curr Opin Neurobiol 2023; 80:102707. [PMID: 36924615 DOI: 10.1016/j.conb.2023.102707] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 01/18/2023] [Accepted: 02/15/2023] [Indexed: 03/16/2023]
Abstract
Spike timing-dependent plasticity (STDP) is a bidirectional form of synaptic plasticity discovered about 30 years ago and based on the relative timing of pre- and post-synaptic spiking activity with a millisecond precision. STDP is thought to be involved in the formation of memory but the millisecond-precision spike-timing required for STDP is difficult to reconcile with the much slower timescales of behavioral learning. This review therefore aims to expose and discuss recent findings about i) the multiple STDP learning rules at both excitatory and inhibitory synapses in vitro, ii) the contribution of STDP-like synaptic plasticity in the formation of memory in vivo and iii) the implementation of STDP rules in artificial neural networks and memristive devices.
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10
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Griesius S, O'Donnell C, Waldron S, Thomas KL, Dwyer DM, Wilkinson LS, Hall J, Robinson ESJ, Mellor JR. Reduced expression of the psychiatric risk gene DLG2 (PSD93) impairs hippocampal synaptic integration and plasticity. Neuropsychopharmacology 2022; 47:1367-1378. [PMID: 35115661 PMCID: PMC9117295 DOI: 10.1038/s41386-022-01277-6] [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: 10/28/2021] [Revised: 01/04/2022] [Accepted: 01/12/2022] [Indexed: 11/15/2022]
Abstract
Copy number variants indicating loss of function in the DLG2 gene have been associated with markedly increased risk for schizophrenia, autism spectrum disorder, and intellectual disability. DLG2 encodes the postsynaptic scaffolding protein DLG2 (PSD93) that interacts with NMDA receptors, potassium channels, and cytoskeletal regulators but the net impact of these interactions on synaptic plasticity, likely underpinning cognitive impairments associated with these conditions, remains unclear. Here, hippocampal CA1 neuronal excitability and synaptic function were investigated in a novel clinically relevant heterozygous Dlg2+/- rat model using ex vivo patch-clamp electrophysiology, pharmacology, and computational modelling. Dlg2+/- rats had reduced supra-linear dendritic integration of synaptic inputs resulting in impaired associative long-term potentiation. This impairment was not caused by a change in synaptic input since NMDA receptor-mediated synaptic currents were, conversely, increased and AMPA receptor-mediated currents were unaffected. Instead, the impairment in associative long-term potentiation resulted from an increase in potassium channel function leading to a decrease in input resistance, which reduced supra-linear dendritic integration. Enhancement of dendritic excitability by blockade of potassium channels or activation of muscarinic M1 receptors with selective allosteric agonist 77-LH-28-1 reduced the threshold for dendritic integration and 77-LH-28-1 rescued the associative long-term potentiation impairment in the Dlg2+/- rats. These findings demonstrate a biological phenotype that can be reversed by compound classes used clinically, such as muscarinic M1 receptor agonists, and is therefore a potential target for therapeutic intervention.
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Affiliation(s)
- Simonas Griesius
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Cian O'Donnell
- Computational Neuroscience Unit, School of Computer Science, Electrical and Electronic Engineering, and Engineering Mathematics, University of Bristol, Bristol, BS8 1UB, UK
| | - Sophie Waldron
- Neuroscience and Mental Health Research Institute, Cardiff, CF24 4HQ, UK
- School of Psychology, Cardiff, CF24 4HQ, UK
| | - Kerrie L Thomas
- Neuroscience and Mental Health Research Institute, Cardiff, CF24 4HQ, UK
- School of Medicine, Cardiff, CF24 4HQ, UK
| | - Dominic M Dwyer
- Neuroscience and Mental Health Research Institute, Cardiff, CF24 4HQ, UK
- School of Psychology, Cardiff, CF24 4HQ, UK
| | - Lawrence S Wilkinson
- Neuroscience and Mental Health Research Institute, Cardiff, CF24 4HQ, UK
- School of Psychology, Cardiff, CF24 4HQ, UK
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff, CF24 4HQ, UK
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, Cardiff, CF24 4HQ, UK
- School of Medicine, Cardiff, CF24 4HQ, UK
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff, CF24 4HQ, UK
| | - Emma S J Robinson
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Jack R Mellor
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, BS8 1TD, UK.
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11
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Anisimova M, van Bommel B, Wang R, Mikhaylova M, Wiegert JS, Oertner TG, Gee CE. Spike-timing-dependent plasticity rewards synchrony rather than causality. Cereb Cortex 2022; 33:23-34. [PMID: 35203089 PMCID: PMC9758582 DOI: 10.1093/cercor/bhac050] [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: 04/17/2021] [Revised: 12/22/2021] [Accepted: 01/24/2022] [Indexed: 11/14/2022] Open
Abstract
Spike-timing-dependent plasticity (STDP) is a candidate mechanism for information storage in the brain, but the whole-cell recordings required for the experimental induction of STDP are typically limited to 1 h. This mismatch of time scales is a long-standing weakness in synaptic theories of memory. Here we use spectrally separated optogenetic stimulation to fire precisely timed action potentials (spikes) in CA3 and CA1 pyramidal cells. Twenty minutes after optogenetic induction of STDP (oSTDP), we observed timing-dependent depression (tLTD) and timing-dependent potentiation (tLTP), depending on the sequence of spiking. As oSTDP does not require electrodes, we could also assess the strength of these paired connections three days later. At this late time point, late tLTP was observed for both causal (CA3 before CA1) and anticausal (CA1 before CA3) timing, but not for asynchronous activity patterns (Δt = 50 ms). Blocking activity after induction of oSTDP prevented stable potentiation. Our results confirm that neurons wire together if they fire together, but suggest that synaptic depression after anticausal activation (tLTD) is a transient phenomenon.
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Affiliation(s)
- Margarita Anisimova
- Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Falkenried 94, D-20251 Hamburg, Germany
| | - Bas van Bommel
- Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Falkenried 94, D-20251 Hamburg, Germany,Institute for Chemistry and Biochemistry, Feie Universität Berlin, Berlin, Germany
| | - Rui Wang
- Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Falkenried 94, D-20251 Hamburg, Germany
| | - Marina Mikhaylova
- Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Falkenried 94, D-20251 Hamburg, Germany,Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jörn Simon Wiegert
- Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Falkenried 94, D-20251 Hamburg, Germany
| | | | - Christine E Gee
- Corresponding author: Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251 Hamburg, Germany.
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12
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Membrane trafficking and positioning of mGluRs at presynaptic and postsynaptic sites of excitatory synapses. Neuropharmacology 2021; 200:108799. [PMID: 34592242 DOI: 10.1016/j.neuropharm.2021.108799] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 08/31/2021] [Accepted: 09/17/2021] [Indexed: 01/21/2023]
Abstract
The plethora of functions of glutamate in the brain are mediated by the complementary actions of ionotropic and metabotropic glutamate receptors (mGluRs). The ionotropic glutamate receptors carry most of the fast excitatory transmission, while mGluRs modulate transmission on longer timescales by triggering multiple intracellular signaling pathways. As such, mGluRs mediate critical aspects of synaptic transmission and plasticity. Interestingly, at synapses, mGluRs operate at both sides of the cleft, and thus bidirectionally exert the effects of glutamate. At postsynaptic sites, group I mGluRs act to modulate excitability and plasticity. At presynaptic sites, group II and III mGluRs act as auto-receptors, modulating release properties in an activity-dependent manner. Thus, synaptic mGluRs are essential signal integrators that functionally couple presynaptic and postsynaptic mechanisms of transmission and plasticity. Understanding how these receptors reach the membrane and are positioned relative to the presynaptic glutamate release site are therefore important aspects of synapse biology. In this review, we will discuss the currently known mechanisms underlying the trafficking and positioning of mGluRs at and around synapses, and how these mechanisms contribute to synaptic functioning. We will highlight outstanding questions and present an outlook on how recent technological developments will move this exciting research field forward.
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13
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Cepeda-Prado EA, Khodaie B, Quiceno GD, Beythien S, Edelmann E, Lessmann V. Calcium-Permeable AMPA Receptors Mediate Timing-Dependent LTP Elicited by Low Repeat Coincident Pre- and Postsynaptic Activity at Schaffer Collateral-CA1 Synapses. Cereb Cortex 2021; 32:1682-1703. [PMID: 34498663 DOI: 10.1093/cercor/bhab306] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 12/26/2022] Open
Abstract
High-frequency stimulation induced long-term potentiation (LTP) and low-frequency stimulation induced LTD are considered as cellular models of memory formation. Interestingly, spike timing-dependent plasticity (STDP) can induce equally robust timing-dependent LTP (t-LTP) and t-LTD in response to low frequency repeats of coincident action potential (AP) firing in presynaptic and postsynaptic cells. Commonly, STDP paradigms relying on 25-100 repeats of coincident AP firing are used to elicit t-LTP or t-LTD, but the minimum number of repeats required for successful STDP is barely explored. However, systematic investigation of physiologically relevant low repeat STDP paradigms is of utmost importance to explain learning mechanisms in vivo. Here, we examined low repeat STDP at Schaffer collateral-CA1 synapses by pairing one presynaptic AP with either one postsynaptic AP (1:1 t-LTP), or a burst of 4 APs (1:4 t-LTP) and found 3-6 repeats to be sufficient to elicit t-LTP. 6× 1:1 t-LTP required postsynaptic Ca2+ influx via NMDARs and L-type VGCCs and was mediated by increased presynaptic glutamate release. In contrast, 1:4 t-LTP depended on postsynaptic metabotropic GluRs and ryanodine receptor signaling and was mediated by postsynaptic insertion of AMPA receptors. Unexpectedly, both 6× t-LTP variants were strictly dependent on activation of postsynaptic Ca2+-permeable AMPARs but were differentially regulated by dopamine receptor signaling. Our data show that synaptic changes induced by only 3-6 repeats of mild STDP stimulation occurring in ≤10 s can take place on time scales observed also during single trial learning.
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Affiliation(s)
- Efrain A Cepeda-Prado
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany
| | - Babak Khodaie
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany.,OVGU International ESF-funded Graduate School ABINEP, Magdeburg 39104, Germany
| | - Gloria D Quiceno
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany
| | - Swantje Beythien
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany
| | - Elke Edelmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany.,OVGU International ESF-funded Graduate School ABINEP, Magdeburg 39104, Germany.,Center for Behavioral Brain Sciences, Magdeburg 39104, Germany
| | - Volkmar Lessmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany.,OVGU International ESF-funded Graduate School ABINEP, Magdeburg 39104, Germany.,Center for Behavioral Brain Sciences, Magdeburg 39104, Germany
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14
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Lipshutz D, Bahroun Y, Golkar S, Sengupta AM, Chklovskii DB. A Biologically Plausible Neural Network for Multichannel Canonical Correlation Analysis. Neural Comput 2021; 33:2309-2352. [PMID: 34412114 DOI: 10.1162/neco_a_01414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/23/2021] [Indexed: 11/04/2022]
Abstract
Cortical pyramidal neurons receive inputs from multiple distinct neural populations and integrate these inputs in separate dendritic compartments. We explore the possibility that cortical microcircuits implement canonical correlation analysis (CCA), an unsupervised learning method that projects the inputs onto a common subspace so as to maximize the correlations between the projections. To this end, we seek a multichannel CCA algorithm that can be implemented in a biologically plausible neural network. For biological plausibility, we require that the network operates in the online setting and its synaptic update rules are local. Starting from a novel CCA objective function, we derive an online optimization algorithm whose optimization steps can be implemented in a single-layer neural network with multicompartmental neurons and local non-Hebbian learning rules. We also derive an extension of our online CCA algorithm with adaptive output rank and output whitening. Interestingly, the extension maps onto a neural network whose neural architecture and synaptic updates resemble neural circuitry and non-Hebbian plasticity observed in the cortex.
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Affiliation(s)
- David Lipshutz
- Center for Computational Neuroscience, Flatiron Institute, New York, NY 10010, U.S.A.
| | - Yanis Bahroun
- Center for Computational Neuroscience, Flatiron Institute, New York, NY 10010, U.S.A.
| | - Siavash Golkar
- Center for Computational Neuroscience, Flatiron Institute, New York, NY 10010, U.S.A.
| | - Anirvan M Sengupta
- Center for Computational Neuroscience, Flatiron Institute, New York, NY 10010, U.S.A., and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 U.S.A.
| | - Dmitri B Chklovskii
- Center for Computational Neuroscience, Flatiron Institute, New York, NY 10010, U.S.A., and Neuroscience Institute, NYU Medical Center, New York, NY 10016, U.S.A.
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15
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Watkins JC, Evans RH, Bayés À, Booker SA, Gibb A, Mabb AM, Mayer M, Mellor JR, Molnár E, Niu L, Ortega A, Pankratov Y, Ramos-Vicente D, Rodríguez-Campuzano A, Rodríguez-Moreno A, Wang LY, Wang YT, Wollmuth L, Wyllie DJA, Zhuo M, Frenguelli BG. 21st century excitatory amino acid research: A Q & A with Jeff Watkins and Dick Evans. Neuropharmacology 2021; 198:108743. [PMID: 34363811 DOI: 10.1016/j.neuropharm.2021.108743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In 1981 Jeff Watkins and Dick Evans wrote what was to become a seminal review on excitatory amino acids (EAAs) and their receptors (Watkins and Evans, 1981). Bringing together various lines of evidence dating back over several decades on: the distribution in the nervous system of putative amino acid neurotransmitters; enzymes involved in their production and metabolism; the uptake and release of amino acids; binding of EAAs to membranes; the pharmacological action of endogenous excitatory amino acids and their synthetic analogues, and notably the actions of antagonists for the excitations caused by both nerve stimulation and exogenous agonists, often using pharmacological tools developed by Jeff and his colleagues, they provided a compelling account for EAAs, especially l-glutamate, as a bona fide neurotransmitter in the nervous system. The rest, as they say, is history, but far from being consigned to history, EAA research is in rude health well into the 21st Century as this series of Special Issues of Neuropharmacology exemplifies. With EAAs and their receptors flourishing across a wide range of disciplines and clinical conditions, we enter into a dialogue with two of the most prominent and influential figures in the early days of EAA research: Jeff Watkins and Dick Evans.
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Affiliation(s)
| | | | - Àlex Bayés
- Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau, Barcelona, Spain and Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Sam A Booker
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Alasdair Gibb
- Research Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Angela M Mabb
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Mark Mayer
- Bldg 35A, Room 3D-904, 35A Convent Drive, NINDS, NIH, Bethesda, MD, 20892, USA
| | - Jack R Mellor
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Elek Molnár
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Li Niu
- Chemistry Department, University at Albany, SUNY, 1400 Washington Ave, Albany, NY, 12222, USA
| | - Arturo Ortega
- Department of Toxicology, Cinvestav, Mexico City, Mexico
| | - Yuriy Pankratov
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - David Ramos-Vicente
- Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau, Barcelona, Spain and Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | | | - Lu-Yang Wang
- Program in Neurosciences & Mental Health, SickKids Research Institute and Department of Physiology, University of Toronto, 555 University Ave, Toronto, Ontario, M5G 1X8, Canada
| | - Yu Tian Wang
- Department of Medicine, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Lonnie Wollmuth
- Depts. of Neurobiology & Behavior and Biochemistry & Cell Biology, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - David J A Wyllie
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Min Zhuo
- Institute of Brain Research, Qingdao International Academician Park, Qingdao, 266000, China
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16
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Tigaret CM, Lin TCE, Morrell ER, Sykes L, Moon AL, O’Donovan MC, Owen MJ, Wilkinson LS, Jones MW, Thomas KL, Hall J. Neurotrophin receptor activation rescues cognitive and synaptic abnormalities caused by hemizygosity of the psychiatric risk gene Cacna1c. Mol Psychiatry 2021; 26:1748-1760. [PMID: 33597718 PMCID: PMC8440217 DOI: 10.1038/s41380-020-01001-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 12/02/2020] [Accepted: 12/10/2020] [Indexed: 02/08/2023]
Abstract
Genetic variation in CACNA1C, which encodes the alpha-1 subunit of CaV1.2 L-type voltage-gated calcium channels, is strongly linked to risk for psychiatric disorders including schizophrenia and bipolar disorder. To translate genetics to neurobiological mechanisms and rational therapeutic targets, we investigated the impact of mutations of one copy of Cacna1c on rat cognitive, synaptic and circuit phenotypes implicated by patient studies. We show that rats hemizygous for Cacna1c harbour marked impairments in learning to disregard non-salient stimuli, a behavioural change previously associated with psychosis. This behavioural deficit is accompanied by dys-coordinated network oscillations during learning, pathway-selective disruption of hippocampal synaptic plasticity, attenuated Ca2+ signalling in dendritic spines and decreased signalling through the Extracellular-signal Regulated Kinase (ERK) pathway. Activation of the ERK pathway by a small-molecule agonist of TrkB/TrkC neurotrophin receptors rescued both behavioural and synaptic plasticity deficits in Cacna1c+/- rats. These results map a route through which genetic variation in CACNA1C can disrupt experience-dependent synaptic signalling and circuit activity, culminating in cognitive alterations associated with psychiatric disorders. Our findings highlight targeted activation of neurotrophin signalling pathways with BDNF mimetic drugs as a genetically informed therapeutic approach for rescuing behavioural abnormalities in psychiatric disorder.
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Affiliation(s)
- Cezar M. Tigaret
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK
| | - Tzu-Ching E. Lin
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK
| | - Edward R. Morrell
- grid.5600.30000 0001 0807 5670School of Psychology, Cardiff University, Cardiff, UK ,grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Lucy Sykes
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK ,Present Address: Neem Biotech, Abertillery, Blaenau Gwent UK
| | - Anna L. Moon
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK ,grid.5600.30000 0001 0807 5670MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical NeurosciencesSchool of Medicine, Cardiff University, Cardiff, UK
| | - Michael C. O’Donovan
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK ,grid.5600.30000 0001 0807 5670MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical NeurosciencesSchool of Medicine, Cardiff University, Cardiff, UK
| | - Michael J. Owen
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK ,grid.5600.30000 0001 0807 5670MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical NeurosciencesSchool of Medicine, Cardiff University, Cardiff, UK
| | - Lawrence S. Wilkinson
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK ,grid.5600.30000 0001 0807 5670School of Psychology, Cardiff University, Cardiff, UK ,grid.5600.30000 0001 0807 5670MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical NeurosciencesSchool of Medicine, Cardiff University, Cardiff, UK
| | - Matthew W. Jones
- grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Kerrie L. Thomas
- grid.5600.30000 0001 0807 5670Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK ,grid.5600.30000 0001 0807 5670School of Bioscience, Cardiff University, Cardiff, UK
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK. .,MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical NeurosciencesSchool of Medicine, Cardiff University, Cardiff, UK.
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17
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Sun J, Liu Y, Baudry M, Bi X. SK2 channel regulation of neuronal excitability, synaptic transmission, and brain rhythmic activity in health and diseases. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118834. [PMID: 32860835 PMCID: PMC7541745 DOI: 10.1016/j.bbamcr.2020.118834] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 08/13/2020] [Accepted: 08/19/2020] [Indexed: 11/20/2022]
Abstract
Small conductance calcium-activated potassium channels (SKs) are solely activated by intracellular Ca2+ and their activation leads to potassium efflux, thereby repolarizing/hyperpolarizing membrane potential. Thus, these channels play a critical role in synaptic transmission, and consequently in information transmission along the neuronal circuits expressing them. SKs are widely but not homogeneously distributed in the central nervous system (CNS). Activation of SKs requires submicromolar cytoplasmic Ca2+ concentrations, which are reached following either Ca2+ release from intracellular Ca2+ stores or influx through Ca2+ permeable membrane channels. Both Ca2+ sensitivity and synaptic levels of SKs are regulated by protein kinases and phosphatases, and degradation pathways. SKs in turn control the activity of multiple Ca2+ channels. They are therefore critically involved in coordinating diverse Ca2+ signaling pathways and controlling Ca2+ signal amplitude and duration. This review highlights recent advances in our understanding of the regulation of SK2 channels and of their roles in normal brain functions, including synaptic plasticity, learning and memory, and rhythmic activities. It will also discuss how alterations in their expression and regulation might contribute to various brain disorders such as Angelman Syndrome, Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Jiandong Sun
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Yan Liu
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Michel Baudry
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Xiaoning Bi
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America.
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18
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Interneuron-specific plasticity at parvalbumin and somatostatin inhibitory synapses onto CA1 pyramidal neurons shapes hippocampal output. Nat Commun 2020; 11:4395. [PMID: 32879322 PMCID: PMC7467931 DOI: 10.1038/s41467-020-18074-8] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 07/31/2020] [Indexed: 12/22/2022] Open
Abstract
The formation and maintenance of spatial representations within hippocampal cell assemblies is strongly dictated by patterns of inhibition from diverse interneuron populations. Although it is known that inhibitory synaptic strength is malleable, induction of long-term plasticity at distinct inhibitory synapses and its regulation of hippocampal network activity is not well understood. Here, we show that inhibitory synapses from parvalbumin and somatostatin expressing interneurons undergo long-term depression and potentiation respectively (PV-iLTD and SST-iLTP) during physiological activity patterns. Both forms of plasticity rely on T-type calcium channel activation to confer synapse specificity but otherwise employ distinct mechanisms. Since parvalbumin and somatostatin interneurons preferentially target perisomatic and distal dendritic regions respectively of CA1 pyramidal cells, PV-iLTD and SST-iLTP coordinate a reprioritisation of excitatory inputs from entorhinal cortex and CA3. Furthermore, circuit-level modelling reveals that PV-iLTD and SST-iLTP cooperate to stabilise place cells while facilitating representation of multiple unique environments within the hippocampal network. Inhibitory interneuron subtypes differentially control place cell representations in CA1. Here, the authors show that parvalbumin and somatostatin interneuron synapses onto CA1 pyramidal neurons exhibit distinct plasticity mechanisms and incorporating this insight into circuit-level modeling leads to stable place cell representations.
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19
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Fernández-Fernández D, Lamas JA. Metabotropic Modulation of Potassium Channels During Synaptic Plasticity. Neuroscience 2020; 456:4-16. [PMID: 32114098 DOI: 10.1016/j.neuroscience.2020.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 02/14/2020] [Accepted: 02/18/2020] [Indexed: 01/06/2023]
Abstract
Besides their primary function mediating the repolarization phase of action potentials, potassium channels exquisitely and ubiquitously regulate the resting membrane potential of neurons and therefore have a key role establishing their intrinsic excitability. This group of proteins is composed of a very diverse collection of voltage-dependent and -independent ion channels, whose specific distribution is finely tuned at the level of the synapse. Both at the presynaptic and postsynaptic membranes, different types of potassium channels are subjected to modulation by second messenger signaling cascades triggered by metabotropic receptors, which in this way serve as a link between neurotransmitter actions and changes in the neuron membrane excitability. On the one hand, by regulating the resting membrane potential of the postsynaptic membrane, potassium channels appear to be critical towards setting the threshold for the induction of long-term potentiation and depression. On the other hand, these channels maintain the presynaptic membrane potential under control, therefore influencing the probability of neurotransmitter release underlying different forms of short-term plasticity. In the present review, we examine in detail the role of metabotropic receptors translating their activation by different neurotransmitters into a final effect modulating several types of potassium channels. Furthermore, we evaluate the consequences that this interplay has on the induction and maintenance of different forms of synaptic plasticity.
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Affiliation(s)
- D Fernández-Fernández
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, Vigo, Galicia, Spain.
| | - J A Lamas
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, Vigo, Galicia, Spain
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20
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Synaptic Plasticity Depends on the Fine-Scale Input Pattern in Thin Dendrites of CA1 Pyramidal Neurons. J Neurosci 2020; 40:2593-2605. [PMID: 32047054 PMCID: PMC7096145 DOI: 10.1523/jneurosci.2071-19.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 01/16/2020] [Accepted: 01/23/2020] [Indexed: 12/19/2022] Open
Abstract
Coordinated long-term plasticity of nearby excitatory synaptic inputs has been proposed to shape experience-related neuronal information processing. To elucidate the induction rules leading to spatially structured forms of synaptic potentiation in dendrites, we explored plasticity of glutamate uncaging-evoked excitatory input patterns with various spatial distributions in perisomatic dendrites of CA1 pyramidal neurons in slices from adult male rats. Coordinated long-term plasticity of nearby excitatory synaptic inputs has been proposed to shape experience-related neuronal information processing. To elucidate the induction rules leading to spatially structured forms of synaptic potentiation in dendrites, we explored plasticity of glutamate uncaging-evoked excitatory input patterns with various spatial distributions in perisomatic dendrites of CA1 pyramidal neurons in slices from adult male rats. We show that (1) the cooperativity rules governing the induction of synaptic LTP depend on dendritic location; (2) LTP of input patterns that are subthreshold or suprathreshold to evoke local dendritic spikes (d-spikes) requires different spatial organization; and (3) input patterns evoking d-spikes can strengthen nearby, nonsynchronous synapses by local heterosynaptic plasticity crosstalk mediated by NMDAR-dependent MEK/ERK signaling. These results suggest that multiple mechanisms can trigger spatially organized synaptic plasticity on various spatial and temporal scales, enriching the ability of neurons to use synaptic clustering for information processing. SIGNIFICANCE STATEMENT A fundamental question in neuroscience is how neuronal feature selectivity is established via the combination of dendritic processing of synaptic input patterns with long-term synaptic plasticity. As these processes have been mostly studied separately, the relationship between the rules of integration and rules of plasticity remained elusive. Here we explore how the fine-grained spatial pattern and the form of voltage integration determine plasticity of different excitatory synaptic input patterns in perisomatic dendrites of CA1 pyramidal cells. We demonstrate that the plasticity rules depend highly on three factors: (1) the location of the input within the dendritic branch (proximal vs distal), (2) the strength of the input pattern (subthreshold or suprathreshold for dendritic spikes), and (3) the stimulation of neighboring synapses.
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21
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Iacobucci GJ, Popescu GK. Spatial Coupling Tunes NMDA Receptor Responses via Ca 2+ Diffusion. J Neurosci 2019; 39:8831-8844. [PMID: 31519826 PMCID: PMC6832682 DOI: 10.1523/jneurosci.0901-19.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 08/11/2019] [Accepted: 09/03/2019] [Indexed: 12/11/2022] Open
Abstract
In the CNS, NMDA receptors generate large and highly regulated Ca2+ signals, which are critical for synaptic development and plasticity. They are highly clustered at postsynaptic sites and along dendritic arbors, but whether this spatial arrangement affects their output is unknown. Synaptic NMDA receptor currents are subject to Ca2+-dependent inactivation (CDI), a type of activity-dependent inhibition that requires intracellular Ca2+ and calmodulin (CaM). We asked whether Ca2+ influx through a single NMDA receptor influences the activity of nearby NMDA receptors, as a possible coupling mechanism. Using cell-attached unitary current recordings from GluN1-2a/GluN2A receptors expressed in human HEK293 cells and from NMDA receptors native to hippocampal neurons from male and female rats, we recorded unitary currents from multichannel patches and used a coupled Markov model to determine the extent of signal coupling (κ). In the absence of extracellular Ca2+, we observed no cooperativity (κ < 0.1), whereas in 1.8 mm external Ca2+, both recombinant and native channels showed substantial negative cooperativity (κ = 0.27). Intracellular Ca2+ chelation or overexpression of a Ca2+-insensitive CaM mutant, reduced coupling, which is consistent with CDI representing the coupling mechanism. In contrast, cooperativity increased substantially (κ = 0.68) when overexpressing the postsynaptic scaffolding protein PSD-95, which increased receptor clustering. Together, these new results demonstrate that NMDA receptor currents are negatively coupled through CDI, and the degree of coupling can be tuned by the distance between receptors. Therefore, channel clustering can influence the activity-dependent reduction in NMDA receptor currents.SIGNIFICANCE STATEMENT At central synapses, NMDA receptors are a major class of excitatory glutamate-gated channels and a source of activity-dependent Ca2+ influx. In turn, fluxed Ca2+ ions bind to calmodulin-primed receptors and reduce further entry, through an autoinhibitory mechanism known as Ca2+ -dependent inactivation (CDI). Here, we show that the diffusion of fluxed Ca2+ between active channels situated within submicroscopic distances amplified receptor inactivation. Thus, calmodulin-mediated gating modulation, an evolutionarily conserved regulatory mechanism, endows synapses with sensitivity to both the temporal sequence and spatial distribution of Ca2+ signals. Perturbations in this mechanism, which coordinates the activity of NMDA receptors within a cluster, may cause signaling alterations that contribute to neuropsychiatric conditions.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14206
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14206
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22
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Huang Y, Hu L, Li H, Huang Y, Li Y, Yang J, Gu J, Xu H. PKA-mediated phosphorylation of CREB and NMDA receptor 2B in the hippocampus of offspring rats is involved in transmission of mental disorders across a generation. Psychiatry Res 2019; 280:112497. [PMID: 31419724 DOI: 10.1016/j.psychres.2019.112497] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 07/28/2019] [Accepted: 07/28/2019] [Indexed: 02/05/2023]
Abstract
This study is aimed at the mechanism of transmission of mental disorders across a generation. We used 10 different stressors to establish an animal model of chronic unpredictable stress (CUS) before pregnancy. Forced swimming test (FST) and open field test (OFT) were used to analyze the behavior of 30-day-old adolescent offspring rats born to stress mothers. Magnetic resonance spectroscopy was used to measure glutamate, gamma-aminobutyric acid (GABA), and glutamine. Phosphate-activated glutaminase (PAG), glutamate decarboxylase (GAD), GABA-transaminase (GABA-T), protein kinase A (PKA), cAMP response element-binding protein (CREB), and N-methyl-D-aspartate (NMDA) receptor 2B (NR2B) were detected by western blot. Adolescent offspring rats in the CUS group exhibited depressive-like behavior in the FST and anxious behavior in the OFT. GAD was increased and GABA-T was decreased, which resulted in an increase in GABA levels and decrease of the glutamate/GABA ratio in the hippocampus of CUS offspring rats. Disruption of the glutamate/GABA-glutamine cycle was related to decrease PKA-mediated phosphorylation of CREB and NR2B in the hippocampus. These findings highlight the importance of mental health of females before pregnancy and suggest that CUS before pregnancy reduces p-CREB and p-NR2B in the offspring hippocampus, which could be responsible for behavioral disorders in the adolescent offspring.
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Affiliation(s)
- Yuejun Huang
- Department of Pediatrics, Second Affiliated Hospital of Shantou University Medical College, North Dongxia Road, Shantou 515041, Guangdong, China
| | - Liu Hu
- Department of Pediatrics, Second Affiliated Hospital of Shantou University Medical College, North Dongxia Road, Shantou 515041, Guangdong, China
| | - Hui Li
- Department of Psychiatry and Psychology, Mental Health Center of Shantou University, Taishan Road, Shantou 515041, Guangdong, China
| | - Yanhong Huang
- Department of Psychiatry and Psychology, Mental Health Center of Shantou University, Taishan Road, Shantou 515041, Guangdong, China
| | - Yuewa Li
- Department of Pediatrics, Second Affiliated Hospital of Shantou University Medical College, North Dongxia Road, Shantou 515041, Guangdong, China
| | - Jianhui Yang
- Department of Pediatrics, Second Affiliated Hospital of Shantou University Medical College, North Dongxia Road, Shantou 515041, Guangdong, China
| | - Jiajie Gu
- Department of Neurosurgery, First Affiliated Hospital of Shantou University Medical College, Changping Road, Shantou 515041, Guangdong, China
| | - Hongwu Xu
- Department of Neurosurgery, First Affiliated Hospital of Shantou University Medical College, Changping Road, Shantou 515041, Guangdong, China.
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23
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Sanderson TM, Georgiou J, Tidball P, Collingridge GL. The Hippocampus Is the Place to Be: Opioid Receptors and LTP. Cell Rep 2019; 28:1117-1118. [PMID: 31365856 DOI: 10.1016/j.celrep.2019.07.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Nam et al. (2019) genetically modulate the expression of astrocytic μ-opioid receptors to reveal they are necessary for drug-induced conditioned place preference. These receptors trigger a mechanism involving metabotropic glutamate receptors to enhance hippocampal long-term potentiation, linking the conditioning to the location.
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Affiliation(s)
- Thomas M Sanderson
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Patrick Tidball
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Graham L Collingridge
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada; Department of Physiology and Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Canada
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24
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Mahajan G, Nadkarni S. Intracellular calcium stores mediate metaplasticity at hippocampal dendritic spines. J Physiol 2019; 597:3473-3502. [PMID: 31099020 PMCID: PMC6636706 DOI: 10.1113/jp277726] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 05/16/2019] [Indexed: 12/21/2022] Open
Abstract
Key points Calcium (Ca2+) entry mediated by NMDA receptors is considered central to the induction of activity‐dependent synaptic plasticity in hippocampal area CA1; this description does not, however, take into account the potential contribution of endoplasmic reticulum (ER) Ca2+ stores. The ER has a heterogeneous distribution in CA1 dendritic spines, and may introduce localized functional differences in Ca2+ signalling between synapses, as suggested by experiments on metabotropic receptor‐dependent long‐term depression. A physiologically detailed computational model of Ca2+ dynamics at a CA3–CA1 excitatory synapse characterizes the contribution of spine ER via metabotropic signalling during plasticity induction protocols. ER Ca2+ release via IP3 receptors modulates NMDA receptor‐dependent plasticity in a graded manner, to selectively promote synaptic depression with relatively diminished effect on LTP induction; this may temper further strengthening at the stronger synapses which are preferentially associated with ER‐containing spines. Acquisition of spine ER may thus represent a local, biophysically plausible ‘metaplastic switch’ at potentiated CA1 synapses, contributing to the plasticity–stability balance in neural circuits.
Abstract Long‐term plasticity mediated by NMDA receptors supports input‐specific, Hebbian forms of learning at excitatory CA3–CA1 connections in the hippocampus. There exists an additional layer of stabilizing mechanisms that act globally as well as locally over multiple time scales to ensure that plasticity occurs in a constrained manner. Here, we investigated the role of calcium (Ca2+) stores associated with the endoplasmic reticulum (ER) in the local regulation of plasticity at individual CA1 synapses. Our study was spurred by (1) the curious observation that ER is sparsely distributed in dendritic spines, but over‐represented in larger spines that are likely to have undergone activity‐dependent strengthening, and (2) evidence suggesting that ER motility at synapses can be rapid, and accompany activity‐regulated spine remodelling. We constructed a physiologically realistic computational model of an ER‐bearing CA1 spine, and examined how IP3‐sensitive Ca2+ stores affect spine Ca2+ dynamics during activity patterns mimicking the induction of long‐term potentiation and long‐term depression (LTD). Our results suggest that the presence of ER modulates NMDA receptor‐dependent plasticity in a graded manner that selectively enhances LTD induction. We propose that ER may locally tune Ca2+‐based plasticity, providing a braking mechanism to mitigate runaway strengthening at potentiated synapses. Our study provides a biophysically accurate description of postsynaptic Ca2+ regulation, and suggests that ER in the spine may promote the re‐use of hippocampal synapses with saturated strengths. Calcium (Ca2+) entry mediated by NMDA receptors is considered central to the induction of activity‐dependent synaptic plasticity in hippocampal area CA1; this description does not, however, take into account the potential contribution of endoplasmic reticulum (ER) Ca2+ stores. The ER has a heterogeneous distribution in CA1 dendritic spines, and may introduce localized functional differences in Ca2+ signalling between synapses, as suggested by experiments on metabotropic receptor‐dependent long‐term depression. A physiologically detailed computational model of Ca2+ dynamics at a CA3–CA1 excitatory synapse characterizes the contribution of spine ER via metabotropic signalling during plasticity induction protocols. ER Ca2+ release via IP3 receptors modulates NMDA receptor‐dependent plasticity in a graded manner, to selectively promote synaptic depression with relatively diminished effect on LTP induction; this may temper further strengthening at the stronger synapses which are preferentially associated with ER‐containing spines. Acquisition of spine ER may thus represent a local, biophysically plausible ‘metaplastic switch’ at potentiated CA1 synapses, contributing to the plasticity–stability balance in neural circuits.
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Affiliation(s)
- Gaurang Mahajan
- Indian Institute of Science Education and Research, Pune, 411 008, India
| | - Suhita Nadkarni
- Indian Institute of Science Education and Research, Pune, 411 008, India
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25
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Madeo G, Bonci A. Rewiring the Addicted Brain: Circuits-Based Treatment for Addiction. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2019; 83:173-184. [PMID: 31097615 DOI: 10.1101/sqb.2018.83.038158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The advent of the noninvasive brain stimulation (NIBS) technique has paved the way for neural circuit-based treatments for addiction. Recently, evidence from both preclinical and clinical studies has evaluated the use of transcranial magnetic stimulation (TMS) as a safe and cost-effective therapeutic tool for substance use disorders (SUDs). Indeed, repetitive TMS impacts on neural activity inducing short- and long-term effects involving neuroplasticity mechanisms locally within the target area of stimulation and the network level throughout the brain. Here, we provide an integrated view of evidence highlighting the mechanisms of TMS-induced effects on modulating the maladaptive brain circuitry of addiction. We then review the preclinical and clinical findings suggesting rTMS as an effective interventional tool for the treatment of SUDs.
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Affiliation(s)
- Graziella Madeo
- Novella Fronda Foundation, Human Science and Brain Research Piazza Castello, 16-35141 Padua, Italy.,Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - Antonello Bonci
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.,Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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26
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Repetitive transcranial magnetic stimulation: Re-wiring the alcoholic human brain. Alcohol 2019; 74:113-124. [PMID: 30420113 DOI: 10.1016/j.alcohol.2018.05.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 05/15/2018] [Accepted: 05/28/2018] [Indexed: 12/28/2022]
Abstract
Alcohol use disorders (AUDs) are one of the leading causes of mortality and morbidity worldwide. In spite of significant advances in understanding the neural underpinnings of AUDs, therapeutic options remain limited. Recent studies have highlighted the potential of repetitive transcranial magnetic stimulation (rTMS) as an innovative, safe, and cost-effective treatment for AUDs. Here, we summarize the fundamental principles of rTMS and its putative mechanisms of action via neurocircuitries related to alcohol addiction. We will also discuss advantages and limitations of rTMS, and argue that Hebbian plasticity and connectivity changes, as well as state-dependency, play a role in shaping some of the long-term effects of rTMS. Visual imaging studies will be linked to recent clinical pilot studies describing the effect of rTMS on alcohol craving and intake, pinpointing new advances, and highlighting conceptual gaps to be filled by future controlled studies.
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27
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Foster WJ, Taylor HBC, Padamsey Z, Jeans AF, Galione A, Emptage NJ. Hippocampal mGluR1-dependent long-term potentiation requires NAADP-mediated acidic store Ca 2+ signaling. Sci Signal 2018; 11:11/558/eaat9093. [PMID: 30482851 DOI: 10.1126/scisignal.aat9093] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Acidic organelles, such as endosomes and lysosomes, store Ca2+ that is released in response to intracellular increases in the second messenger nicotinic acid adenine dinucleotide phosphate (NAADP). In neurons, NAADP and Ca2+ signaling contribute to synaptic plasticity, a process of activity-dependent long-term potentiation (LTP) [or, alternatively, long-term depression (LTD)] of synaptic strength and neuronal transmission that is critical for neuronal function and memory formation. We explored the function of and mechanisms regulating acidic Ca2+ store signaling in murine hippocampal neurons. We found that metabotropic glutamate receptor 1 (mGluR1) was coupled to NAADP signaling that elicited Ca2+ release from acidic stores. In turn, this released Ca2+-mediated mGluR1-dependent LTP by transiently inhibiting SK-type K+ channels, possibly through the activation of protein phosphatase 2A. Genetically removing two-pore channels (TPCs), which are endolysosomal-specific ion channels, switched the polarity of plasticity from LTP to LTD, indicating the importance of specific receptor store coupling and providing mechanistic insight into how mGluR1 can produce both synaptic potentiation and synaptic depression.
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Affiliation(s)
- William J Foster
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Henry B C Taylor
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Zahid Padamsey
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Alexander F Jeans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Nigel J Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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28
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Patel S, Brailoiu E. Thinking through acidic Ca 2+ stores. Sci Signal 2018; 11:11/558/eaau3342. [PMID: 30482848 DOI: 10.1126/scisignal.aau3342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Glutamate signaling regulates neuronal activity and synaptic plasticity, which underlies learning and memory. In this issue of Science Signaling, Foster et al found that metabotropic glutamate receptors mediate long-term potentiation in hippocampal neurons by mobilizing acidic endolysosomal Ca2+ stores through the intracellular messenger NAADP.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK.
| | - Eugen Brailoiu
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
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29
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Park P, Kang H, Sanderson TM, Bortolotto ZA, Georgiou J, Zhuo M, Kaang BK, Collingridge GL. The Role of Calcium-Permeable AMPARs in Long-Term Potentiation at Principal Neurons in the Rodent Hippocampus. Front Synaptic Neurosci 2018; 10:42. [PMID: 30524263 PMCID: PMC6262052 DOI: 10.3389/fnsyn.2018.00042] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Accepted: 11/05/2018] [Indexed: 11/25/2022] Open
Abstract
Long-term potentiation (LTP) at hippocampal CA1 synapses is classically triggered by the synaptic activation of NMDA receptors (NMDARs). More recently, it has been shown that calcium-permeable (CP) AMPA receptors (AMPARs) can also trigger synaptic plasticity at these synapses. Here, we review this literature with a focus on recent evidence that CP-AMPARs are critical for the induction of the protein kinase A (PKA)- and protein synthesis-dependent component of LTP.
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Affiliation(s)
- Pojeong Park
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Heather Kang
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Thomas M Sanderson
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea.,Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Zuner A Bortolotto
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Min Zhuo
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Bong-Kiun Kaang
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea
| | - Graham L Collingridge
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
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30
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Neuhofer D, Kalivas P. Metaplasticity at the addicted tetrapartite synapse: A common denominator of drug induced adaptations and potential treatment target for addiction. Neurobiol Learn Mem 2018; 154:97-111. [PMID: 29428364 PMCID: PMC6112115 DOI: 10.1016/j.nlm.2018.02.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 01/26/2018] [Accepted: 02/07/2018] [Indexed: 11/22/2022]
Abstract
In light of the current worldwide addiction epidemic, the need for successful therapies is more urgent than ever. Although we made substantial progress in our basic understanding of addiction, reliable therapies are lacking. Since 40-60% of patients treated for substance use disorder return to active substance use within a year following treatment discharge, alleviating the vulnerability to relapse is regarded as the most promising avenue for addiction therapy. Preclinical addiction research often focuses on maladaptive synaptic plasticity within the reward pathway. However, drug induced neuroadaptations do not only lead to a strengthening of distinct drug associated cues and drug conditioned behaviors, but also seem to increase plasticity thresholds for environmental stimuli that are not associated with the drug. This form of higher order plasticity, or synaptic metaplasticity, is not expressed as a change in the efficacy of synaptic transmission but as a change in the direction or degree of plasticity induced by a distinct stimulation pattern. Experimental addiction research has demonstrated metaplasticity after exposure to multiple classes of addictive drugs. In this review we will focus on the concept of synaptic metaplasticity in the context of preclinical addiction research. We will take a closer look at the tetrapartite glutamatergic synapse and outline forms of metaplasticity that have been described at the addicted synapse. Finally we will discuss the different potential avenues for pharmacotherapies that target glutamatergic synaptic plasticity and metaplasticity. Here we will argue that aberrant metaplasticity renders the reward seeking circuitry more rigid and hence less able to adapt to changing environmental contingencies. An understanding of the molecular mechanisms that underlie this metaplasticity is crucial for the development of new strategies for addiction therapy. The correction of drug-induced metaplasticity could be used to support behavioral and pharmacotherapies for the treatment of addiction.
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Affiliation(s)
- Daniela Neuhofer
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, United States.
| | - Peter Kalivas
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, United States
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31
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Tambasco N, Romoli M, Calabresi P. Selective basal ganglia vulnerability to energy deprivation: Experimental and clinical evidences. Prog Neurobiol 2018; 169:55-75. [DOI: 10.1016/j.pneurobio.2018.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 07/24/2018] [Accepted: 07/27/2018] [Indexed: 02/07/2023]
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32
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Convergent Metabotropic Signaling Pathways Inhibit SK Channels to Promote Synaptic Plasticity in the Hippocampus. J Neurosci 2018; 38:9252-9262. [PMID: 30242046 PMCID: PMC6199408 DOI: 10.1523/jneurosci.1160-18.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/16/2018] [Accepted: 08/09/2018] [Indexed: 12/27/2022] Open
Abstract
Hebbian synaptic plasticity at hippocampal Schaffer collateral synapses is tightly regulated by postsynaptic small conductance (SK) channels that restrict NMDA receptor activity. SK channels are themselves modulated by G-protein-coupled signaling pathways, but it is not clear under what conditions these are activated to enable synaptic plasticity. Here, we show that muscarinic M1 receptor (M1R) and type 1 metabotropic glutamate receptor (mGluR1) signaling pathways, which are known to inhibit SK channels and thereby disinhibit NMDA receptors, converge to facilitate spine calcium transients during the induction of long-term potentiation (LTP) at hippocampal Schaffer collateral synapses onto CA1 pyramidal neurons of male rats. Furthermore, mGluR1 activation is required for LTP induced by reactivated place-cell firing patterns that occur in sharp-wave ripple events during rest or sleep. In contrast, M1R activation is required for LTP induced by place-cell firing patterns during exploration. Thus, we describe a common mechanism that enables synaptic plasticity during both encoding and consolidation of memories within hippocampal circuits.SIGNIFICANCE STATEMENT Memory ensembles in the hippocampus are formed during active exploration and consolidated during rest or sleep. These two distinct phases each require strengthening of synaptic connections by long-term potentiation (LTP). The neuronal activity patterns in each phase are very different, which makes it hard to map generalized rules for LTP induction onto both formation and consolidation phases. In this study, we show that inhibition of postsynaptic SK channels is a common necessary feature of LTP induction and that SK channel inhibition is achieved by separate but convergent metabotropic signaling pathways. Thus, we reveal a common mechanism for enabling LTP under distinct behavioral conditions.
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33
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Palacios-Filardo J, Mellor JR. Neuromodulation of hippocampal long-term synaptic plasticity. Curr Opin Neurobiol 2018; 54:37-43. [PMID: 30212713 PMCID: PMC6367596 DOI: 10.1016/j.conb.2018.08.009] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 07/26/2018] [Accepted: 08/15/2018] [Indexed: 12/31/2022]
Abstract
Acetylcholine, noradrenaline, dopamine and serotonin all facilitate long-term synaptic plasticity. Neuromodulators facilitate long-term synaptic plasticity by common and divergent mechanisms. Common mechanisms include NMDA receptor facilitation by potassium channel inhibition, gliotransmission and disinhibition. Divergent mechanisms include diversity of disinhibition and temporal and spatial neuromodulator release.
Multiple neuromodulators including acetylcholine, noradrenaline, dopamine and serotonin are released in response to uncertainty to focus attention on events where the predicted outcome does not match observed reality. In these situations, internal representations need to be updated, a process that requires long-term synaptic plasticity. Through a variety of common and divergent mechanisms, it is recently shown that all these neuromodulators facilitate the induction and/or expression of long-term synaptic plasticity within the hippocampus. Under physiological conditions, this may be critical for suprathreshold induction of plasticity endowing neuromodulators with a gating function and providing a mechanism by which neuromodulators enable the targeted updating of memory with relevant information to improve the accuracy of future predictions.
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Affiliation(s)
- Jon Palacios-Filardo
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Jack R Mellor
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK.
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34
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Rongala UB, Spanne A, Mazzoni A, Bengtsson F, Oddo CM, Jörntell H. Intracellular Dynamics in Cuneate Nucleus Neurons Support Self-Stabilizing Learning of Generalizable Tactile Representations. Front Cell Neurosci 2018; 12:210. [PMID: 30108485 PMCID: PMC6079306 DOI: 10.3389/fncel.2018.00210] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/26/2018] [Indexed: 12/12/2022] Open
Abstract
How the brain represents the external world is an unresolved issue for neuroscience, which could provide fundamental insights into brain circuitry operation and solutions for artificial intelligence and robotics. The neurons of the cuneate nucleus form the first interface for the sense of touch in the brain. They were previously shown to have a highly skewed synaptic weight distribution for tactile primary afferent inputs, suggesting that their connectivity is strongly shaped by learning. Here we first characterized the intracellular dynamics and inhibitory synaptic inputs of cuneate neurons in vivo and modeled their integration of tactile sensory inputs. We then replaced the tactile inputs with input from a sensorized bionic fingertip and modeled the learning-induced representations that emerged from varied sensory experiences. The model reproduced both the intrinsic membrane dynamics and the synaptic weight distributions observed in cuneate neurons in vivo. In terms of higher level model properties, individual cuneate neurons learnt to identify specific sets of correlated sensors, which at the population level resulted in a decomposition of the sensor space into its recurring high-dimensional components. Such vector components could be applied to identify both past and novel sensory experiences and likely correspond to the fundamental haptic input features these neurons encode in vivo. In addition, we show that the cuneate learning architecture is robust to a wide range of intrinsic parameter settings due to the neuronal intrinsic dynamics. Therefore, the architecture is a potentially generic solution for forming versatile representations of the external world in different sensor systems.
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Affiliation(s)
- Udaya B Rongala
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Anton Spanne
- Section for Neurobiology, Department of Experimental Medical Sciences, Biomedical Center, Lund University, Lund, Sweden
| | - Alberto Mazzoni
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Fredrik Bengtsson
- Section for Neurobiology, Department of Experimental Medical Sciences, Biomedical Center, Lund University, Lund, Sweden
| | - Calogero M Oddo
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Henrik Jörntell
- Section for Neurobiology, Department of Experimental Medical Sciences, Biomedical Center, Lund University, Lund, Sweden
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35
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Theis AK, Rózsa B, Katona G, Schmitz D, Johenning FW. Voltage Gated Calcium Channel Activation by Backpropagating Action Potentials Downregulates NMDAR Function. Front Cell Neurosci 2018; 12:109. [PMID: 29755321 PMCID: PMC5932410 DOI: 10.3389/fncel.2018.00109] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 04/03/2018] [Indexed: 12/20/2022] Open
Abstract
The majority of excitatory synapses are located on dendritic spines of cortical glutamatergic neurons. In spines, compartmentalized Ca2+ signals transduce electrical activity into specific long-term biochemical and structural changes. Action potentials (APs) propagate back into the dendritic tree and activate voltage gated Ca2+ channels (VGCCs). For spines, this global mode of spine Ca2+ signaling is a direct biochemical feedback of suprathreshold neuronal activity. We previously demonstrated that backpropagating action potentials (bAPs) result in long-term enhancement of spine VGCCs. This activity-dependent VGCC plasticity results in a large interspine variability of VGCC Ca2+ influx. Here, we investigate how spine VGCCs affect glutamatergic synaptic transmission. We combined electrophysiology, two-photon Ca2+ imaging and two-photon glutamate uncaging in acute brain slices from rats. T- and R-type VGCCs were the dominant depolarization-associated Ca2+conductances in dendritic spines of excitatory layer 2 neurons and do not affect synaptic excitatory postsynaptic potentials (EPSPs) measured at the soma. Using two-photon glutamate uncaging, we compared the properties of glutamatergic synapses of single spines that express different levels of VGCCs. While VGCCs contributed to EPSP mediated Ca2+ influx, the amount of EPSP mediated Ca2+ influx is not determined by spine VGCC expression. On a longer timescale, the activation of VGCCs by bAP bursts results in downregulation of spine NMDAR function.
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Affiliation(s)
- Anne-Kathrin Theis
- Neuroscience Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Balázs Rózsa
- Laboratory of 3D Functional Network and Dendritic Imaging, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter University, Budapest, Hungary
| | - Gergely Katona
- Faculty of Information Technology and Bionics, Pázmány Péter University, Budapest, Hungary
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany.,Einstein Center for Neuroscience, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany.,Cluster of Excellence "Neurocure", Berlin, Germany.,DZNE-German Center for Neurodegenerative Disease, Berlin, Germany
| | - Friedrich W Johenning
- Neuroscience Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany.,Einstein Center for Neuroscience, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
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36
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O'Riordan KJ, Hu NW, Rowan MJ. Physiological activation of mGlu5 receptors supports the ion channel function of NMDA receptors in hippocampal LTD induction in vivo. Sci Rep 2018. [PMID: 29535352 PMCID: PMC5849730 DOI: 10.1038/s41598-018-22768-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Synaptic long-term depression (LTD) is believed to underlie critical mnemonic processes in the adult hippocampus. The roles of the metabotropic and ionotropic actions of glutamate in the induction of synaptic LTD by electrical low-frequency stimulation (LFS) in the living adult animal is poorly understood. Here we examined the requirement for metabotropic glutamate (mGlu) and NMDA receptors in LTD induction in anaesthetized adult rats. LTD induction was primarily dependent on NMDA receptors and required the involvement of both the ion channel function and GluN2B subunit of the receptor. Endogenous mGlu5 receptor activation necessitated the local application of relatively high doses of either competitive or non-competitive NMDA receptor antagonists to block LTD induction. Moreover, boosting endogenous glutamate activation of mGlu5 receptors with a positive allosteric modulator lowered the threshold for NMDA receptor-dependent LTD induction by weak LFS. The present data provide support in the living animal that NMDA receptor-dependent LTD is boosted by endogenously released glutamate activation of mGlu5 receptors. Given the predominant perisynaptic location of mGlu5 receptors, the present findings emphasize the need to further evaluate the contribution and mechanisms of these receptors in NMDA receptor-dependent synaptic plasticity in the adult hippocampus in vivo.
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Affiliation(s)
- Kenneth J O'Riordan
- Department of Pharmacology and Therapeutics and Institute of Neuroscience, Watts Building, Trinity College, Dublin, 2, Ireland
| | - Neng-Wei Hu
- Department of Pharmacology and Therapeutics and Institute of Neuroscience, Watts Building, Trinity College, Dublin, 2, Ireland. .,Department of Gerontology, Yijishan Hospital, Wannan Medical College, Wuhu, China. .,Department of Physiology and Neurobiology, Zhengzhou University School of Medicine, Zhengzhou, 450001, China.
| | - Michael J Rowan
- Department of Pharmacology and Therapeutics and Institute of Neuroscience, Watts Building, Trinity College, Dublin, 2, Ireland.
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Jones SL, To MS, Stuart GJ. Dendritic small conductance calcium-activated potassium channels activated by action potentials suppress EPSPs and gate spike-timing dependent synaptic plasticity. eLife 2017; 6:30333. [PMID: 29058675 PMCID: PMC5679750 DOI: 10.7554/elife.30333] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 10/22/2017] [Indexed: 11/24/2022] Open
Abstract
Small conductance calcium-activated potassium channels (SK channels) are present in spines and can be activated by backpropagating action potentials (APs). This suggests they may play a critical role in spike-timing dependent synaptic plasticity (STDP). Consistent with this idea, EPSPs in both cortical and hippocampal pyramidal neurons were suppressed by preceding APs in an SK-dependent manner. In cortical pyramidal neurons EPSP suppression by preceding APs depended on their precise timing as well as the distance of activated synapses from the soma, was dendritic in origin, and involved SK-dependent suppression of NMDA receptor activation. As a result SK channel activation by backpropagating APs gated STDP induction during low-frequency AP-EPSP pairing, with both LTP and LTD absent under control conditions but present after SK channel block. These findings indicate that activation of SK channels in spines by backpropagating APs plays a key role in regulating both EPSP amplitude and STDP induction.
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Affiliation(s)
- Scott L Jones
- Eccles Institute of Neuroscience and Australian Research Council Centre of Excellence for Integrative Brain Function, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Minh-Son To
- Eccles Institute of Neuroscience and Australian Research Council Centre of Excellence for Integrative Brain Function, John Curtin School of Medical Research, Australian National University, Canberra, Australia.,Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia
| | - Greg J Stuart
- Eccles Institute of Neuroscience and Australian Research Council Centre of Excellence for Integrative Brain Function, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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Increased Prevalence of Calcium Transients across the Dendritic Arbor during Place Field Formation. Neuron 2017; 96:490-504.e5. [PMID: 29024668 DOI: 10.1016/j.neuron.2017.09.029] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/09/2017] [Accepted: 09/19/2017] [Indexed: 12/31/2022]
Abstract
Hippocampal place cell ensembles form a cognitive map of space during exposure to novel environments. However, surprisingly little evidence exists to support the idea that synaptic plasticity in place cells is involved in forming new place fields. Here we used high-resolution functional imaging to determine the signaling patterns in CA1 soma, dendrites, and axons associated with place field formation when mice are exposed to novel virtual environments. We found that putative local dendritic spikes often occur prior to somatic place field firing. Subsequently, the first occurrence of somatic place field firing was associated with widespread regenerative dendritic events, which decreased in prevalence with increased novel environment experience. This transient increase in regenerative events was likely facilitated by a reduction in dendritic inhibition. Since regenerative dendritic events can provide the depolarization necessary for Hebbian potentiation, these results suggest that activity-dependent synaptic plasticity underlies the formation of many CA1 place fields.
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Diana M, Raij T, Melis M, Nummenmaa A, Leggio L, Bonci A. Rehabilitating the addicted brain with transcranial magnetic stimulation. Nat Rev Neurosci 2017; 18:685-693. [PMID: 28951609 DOI: 10.1038/nrn.2017.113] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Substance use disorders (SUDs) are one of the leading causes of morbidity and mortality worldwide. In spite of considerable advances in understanding the neural underpinnings of SUDs, therapeutic options remain limited. Recent studies have highlighted the potential of transcranial magnetic stimulation (TMS) as an innovative, safe and cost-effective treatment for some SUDs. Repetitive TMS (rTMS) influences neural activity in the short and long term by mechanisms involving neuroplasticity both locally, under the stimulating coil, and at the network level, throughout the brain. The long-term neurophysiological changes induced by rTMS have the potential to affect behaviours relating to drug craving, intake and relapse. Here, we review TMS mechanisms and evidence that rTMS is opening new avenues in addiction treatments.
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Affiliation(s)
- Marco Diana
- 'G. Minardi' Laboratory for Cognitive Neuroscience, Department of Chemistry and Pharmacy, University of Sassari, 07100 Sassari, Italy
| | - Tommi Raij
- Shirley Ryan AbilityLab, Center for Brain Stimulation, the Department of Physical Medicine and Rehabilitation and the Department of Neurobiology, Northwestern University, Chicago, Illinois 60611, USA
| | - Miriam Melis
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy
| | - Aapo Nummenmaa
- Massachusetts General Hospital (MGH)/Massachusetts Institute of Technology (MIT)/Harvard Medical School (HMS) Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Boston, Massachusetts 02129, USA
| | - Lorenzo Leggio
- Section on Clinical Psychoneuroendocrinology and Neuropsychopharmacology, US National Institute on Alcohol Abuse and Alcoholism Division of Intramural Clinical and Biological Research (NIAAA DICBR) and US National Institute on Drug Abuse Intramural Research Program (NIDA IRP), NIH (National Institutes of Health), Bethesda, Maryland 20892, USA; and at the Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island 02912, USA
| | - Antonello Bonci
- US National Institute on Drug Abuse Intramural Research Program (NIDA IRP); and at the Departments of Neuroscience and Psychiatry, Johns Hopkins University, Baltimore, Maryland 21224, USA
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Activation of Group II Metabotropic Glutamate Receptors Promotes LTP Induction at Schaffer Collateral-CA1 Pyramidal Cell Synapses by Priming NMDA Receptors. J Neurosci 2017; 36:11521-11531. [PMID: 27911756 DOI: 10.1523/jneurosci.1519-16.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 09/20/2016] [Accepted: 09/23/2016] [Indexed: 12/31/2022] Open
Abstract
It is well established that selective activation of group I metabotropic glutamate (mGlu) receptors induces LTD of synaptic transmission at Schaffer collateral-CA1 synapses. In contrast, application of 1S,3R-ACPD, a mixed agonist at group I and group II mGlu receptors, induces LTP. Using whole-cell recordings from CA1 pyramidal cells and field recordings in the hippocampal CA1 region, we investigated the specific contribution of group II mGlu receptors to synaptic plasticity at Schaffer collateral-CA1 synapses in acute slices of adult mice. Pharmacological activation of group II mGlu receptors (mGlu2 and mGlu3 receptors) with the specific agonist LY354740 in conjunction with electrical stimulation induced postsynaptic LTP. This form of plasticity requires coactivation of NMDA receptors (NMDARs). Group II mGlu receptor activation led to PKC-dependent phosphorylation of the GluN1 subunit. We found that both synaptic and extrasynaptic NMDARs, which are differentially modulated by mGlu2 and mGlu3 receptors, contribute to LTP induction. Furthermore, LTP initiated by activation of group II mGlu receptors was not occluded by LTP induced with high-frequency trains of stimuli. However, the phosphorylation of NMDARs mediated by group II mGlu receptor activation led to a priming effect that enhanced subsequent high-frequency stimulation-induced LTP. These findings reveal a novel metaplastic mechanism through which group II mGlu receptors modulate synaptic function at the Schaffer collateral input to CA1 pyramidal cells, thereby lowering the threshold to induce plasticity. SIGNIFICANCE STATEMENT The group II metabotropic glutamate (mGlu II) receptors exert a well characterized action on presynaptic neuron terminals to modulate neurotransmitter release. Here, we show that these receptors also have postsynaptic effects in promoting the induction of synaptic plasticity. Using an electrophysiological approach including field and whole-cell patch recording in hippocampi from wild-type and transgenic mice, we show that activation of group II mGlu receptors enhances NMDA receptor (NMDAR)-mediated currents through PKC-dependent phosphorylation. This priming of NMDARs lowers the threshold for the induction of LTP of synaptic transmission. These findings may also provide new insights into the mechanisms through which drugs targeting mGlu II receptors alleviate hypoglutamatergic conditions such as those occurring in certain brain disorders such as schizophrenia.
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Cannady R, McGonigal JT, Newsom RJ, Woodward JJ, Mulholland PJ, Gass JT. Prefrontal Cortex K Ca2 Channels Regulate mGlu 5-Dependent Plasticity and Extinction of Alcohol-Seeking Behavior. J Neurosci 2017; 37:4359-4369. [PMID: 28320841 PMCID: PMC5413180 DOI: 10.1523/jneurosci.2873-16.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 12/17/2022] Open
Abstract
Identifying novel treatments that facilitate extinction learning could enhance cue-exposure therapy and reduce high relapse rates in alcoholics. Activation of mGlu5 receptors in the infralimbic prefrontal cortex (IL-PFC) facilitates learning during extinction of cue-conditioned alcohol-seeking behavior. Small-conductance calcium-activated potassium (KCa2) channels have also been implicated in extinction learning of fear memories, and mGlu5 receptor activation can reduce KCa2 channel function. Using a combination of electrophysiological, pharmacological, and behavioral approaches, this study examined KCa2 channels as a novel target to facilitate extinction of alcohol-seeking behavior in rats. This study also explored related neuronal and synaptic mechanisms within the IL-PFC that underlie mGlu5-dependent enhancement of extinction learning. Using whole-cell patch-clamp electrophysiology, activation of mGlu5 in ex vivo slices significantly reduced KCa2 channel currents in layer V IL-PFC pyramidal neurons, confirming functional downregulation of KCa2 channel activity by mGlu5 receptors. Additionally, positive modulation of KCa2 channels prevented mGlu5 receptor-dependent facilitation of long-term potentiation in the IL-PFC. Systemic and intra-IL-PFC treatment with apamin (KCa2 channel allosteric inhibitor) significantly enhanced extinction of alcohol-seeking behavior across multiple extinction sessions, an effect that persisted for 3 weeks, but was not observed after apamin microinfusions into the prelimbic PFC. Positive modulation of IL-PFC KCa2 channels significantly attenuated mGlu5-dependent facilitation of alcohol cue-conditioned extinction learning. These data suggest that mGlu5-dependent facilitation of extinction learning and synaptic plasticity in the IL-PFC involves functional inhibition of KCa2 channels. Moreover, these findings demonstrate that KCa2 channels are a novel target to facilitate long-lasting extinction of alcohol-seeking behavior.SIGNIFICANCE STATEMENT Alcohol use disorder is a chronic relapsing disorder that is associated with compulsive alcohol-seeking behavior. One of the main causes of alcohol relapse is the craving caused by environmental cues that are associated with alcohol. These cues are formed by normal learning and memory principles, and the understanding of the brain mechanisms that help form these associations can lead to the development of drugs and/or behavior therapies that reduce the impact that these cues have on relapse in alcoholics.
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Affiliation(s)
- Reginald Cannady
- Department of Neuroscience
- Department of Psychiatry & Behavioral Sciences, and
| | | | | | - John J Woodward
- Department of Neuroscience
- Department of Psychiatry & Behavioral Sciences, and
| | | | - Justin T Gass
- Department of Neuroscience,
- Department of Psychiatry & Behavioral Sciences, and
- Charleston Alcohol Research Center, Addiction Sciences Division, College of Health Professions, Medical University of South Carolina, Charleston, South Carolina 29425
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Jaramillo J, Kempter R. Phase precession: a neural code underlying episodic memory? Curr Opin Neurobiol 2017; 43:130-138. [PMID: 28390862 DOI: 10.1016/j.conb.2017.02.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 01/25/2017] [Accepted: 02/08/2017] [Indexed: 11/29/2022]
Abstract
In the hippocampal formation, the sequential activation of place-specific cells represents a conceptual model for the spatio-temporal events that assemble episodic memories. The imprinting of behavioral sequences in hippocampal networks might be achieved via spike-timing-dependent plasticity and phase precession of the spiking activity of neurons. It is unclear, however, whether phase precession plays an active role by enabling sequence learning via synaptic plasticity or whether phase precession passively reflects retrieval dynamics. Here we examine these possibilities in the context of potential mechanisms generating phase precession. Knowledge of these mechanisms would allow to selectively alter phase precession and test its role in episodic memory. We finally review the few successful approaches to degrade phase precession and the resulting impact on behavior.
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Affiliation(s)
- Jorge Jaramillo
- Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Philippstr. 13, 10115 Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, Philippstr. 13, 10115 Berlin, Germany
| | - Richard Kempter
- Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Philippstr. 13, 10115 Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, Philippstr. 13, 10115 Berlin, Germany.
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Edelmann E, Cepeda-Prado E, Leßmann V. Coexistence of Multiple Types of Synaptic Plasticity in Individual Hippocampal CA1 Pyramidal Neurons. Front Synaptic Neurosci 2017; 9:7. [PMID: 28352224 PMCID: PMC5348504 DOI: 10.3389/fnsyn.2017.00007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/20/2017] [Indexed: 02/05/2023] Open
Abstract
Understanding learning and memory mechanisms is an important goal in neuroscience. To gain insights into the underlying cellular mechanisms for memory formation, synaptic plasticity processes are studied with various techniques in different brain regions. A valid model to scrutinize different ways to enhance or decrease synaptic transmission is recording of long-term potentiation (LTP) or long-term depression (LTD). At the single cell level, spike timing-dependent plasticity (STDP) protocols have emerged as a powerful tool to investigate synaptic plasticity with stimulation paradigms that also likely occur during memory formation in vivo. Such kind of plasticity can be induced by different STDP paradigms with multiple repeat numbers and stimulation patterns. They subsequently recruit or activate different molecular pathways and neuromodulators for induction and expression of STDP. Dopamine (DA) and brain-derived neurotrophic factor (BDNF) have been recently shown to be important modulators for hippocampal STDP at Schaffer collateral (SC)-CA1 synapses and are activated exclusively by distinguishable STDP paradigms. Distinct types of parallel synaptic plasticity in a given neuron depend on specific subcellular molecular prerequisites. Since the basal and apical dendrites of CA1 pyramidal neurons are known to be heterogeneous, and distance-dependent dendritic gradients for specific receptors and ion channels are described, the dendrites might provide domain specific locations for multiple types of synaptic plasticity in the same neuron. In addition to the distinct signaling and expression mechanisms of various types of LTP and LTD, activation of these different types of plasticity might depend on background brain activity states. In this article, we will discuss some ideas why multiple forms of synaptic plasticity can simultaneously and independently coexist and can contribute so effectively to increasing the efficacy of memory storage and processing capacity of the brain. We hypothesize that resolving the subcellular location of t-LTP and t-LTD mechanisms that are regulated by distinct neuromodulator systems will be essential to reach a more cohesive understanding of synaptic plasticity in memory formation.
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Affiliation(s)
- Elke Edelmann
- Institute of Physiology, Otto-von-Guericke UniversityMagdeburg, Germany; Center for Behavioral Brain Sciences, Otto-von-Guericke UniversityMagdeburg, Germany
| | | | - Volkmar Leßmann
- Institute of Physiology, Otto-von-Guericke UniversityMagdeburg, Germany; Center for Behavioral Brain Sciences, Otto-von-Guericke UniversityMagdeburg, Germany
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44
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Díez-García A, Barros-Zulaica N, Núñez Á, Buño W, Fernández de Sevilla D. Bidirectional Hebbian Plasticity Induced by Low-Frequency Stimulation in Basal Dendrites of Rat Barrel Cortex Layer 5 Pyramidal Neurons. Front Cell Neurosci 2017; 11:8. [PMID: 28203145 PMCID: PMC5285403 DOI: 10.3389/fncel.2017.00008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/12/2017] [Indexed: 11/15/2022] Open
Abstract
According to Hebb's original hypothesis (Hebb, 1949), synapses are reinforced when presynaptic activity triggers postsynaptic firing, resulting in long-term potentiation (LTP) of synaptic efficacy. Long-term depression (LTD) is a use-dependent decrease in synaptic strength that is thought to be due to synaptic input causing a weak postsynaptic effect. Although the mechanisms that mediate long-term synaptic plasticity have been investigated for at least three decades not all question have as yet been answered. Therefore, we aimed at determining the mechanisms that generate LTP or LTD with the simplest possible protocol. Low-frequency stimulation of basal dendrite inputs in Layer 5 pyramidal neurons of the rat barrel cortex induces LTP. This stimulation triggered an EPSP, an action potential (AP) burst, and a Ca2+ spike. The same stimulation induced LTD following manipulations that reduced the Ca2+ spike and Ca2+ signal or the AP burst. Low-frequency whisker deflections induced similar bidirectional plasticity of action potential evoked responses in anesthetized rats. These results suggest that both in vitro and in vivo similar mechanisms regulate the balance between LTP and LTD. This simple induction form of bidirectional hebbian plasticity could be present in the natural conditions to regulate the detection, flow, and storage of sensorimotor information.
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Affiliation(s)
- Andrea Díez-García
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain
| | - Natali Barros-Zulaica
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain
| | - Ángel Núñez
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain
| | - Washington Buño
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC) Madrid, Spain
| | - David Fernández de Sevilla
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de MadridMadrid, Spain; Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)Madrid, Spain
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45
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Differential Regulation of NMDA Receptor-Mediated Transmission by SK Channels Underlies Dorsal-Ventral Differences in Dynamics of Schaffer Collateral Synaptic Function. J Neurosci 2017; 37:1950-1964. [PMID: 28093473 DOI: 10.1523/jneurosci.3196-16.2017] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/27/2016] [Accepted: 01/07/2017] [Indexed: 11/21/2022] Open
Abstract
Behavioral, physiological, and anatomical evidence indicates that the dorsal and ventral zones of the hippocampus have distinct roles in cognition. How the unique functions of these zones might depend on differences in synaptic and neuronal function arising from the strikingly different gene expression profiles exhibited by dorsal and ventral CA1 pyramidal cells is unclear. To begin to address this question, we investigated the mechanisms underlying differences in synaptic transmission and plasticity at dorsal and ventral Schaffer collateral (SC) synapses in the mouse hippocampus. We find that, although basal synaptic transmission is similar, SC synapses in the dorsal and ventral hippocampus exhibit markedly different responses to θ frequency patterns of stimulation. In contrast to dorsal hippocampus, θ frequency stimulation fails to elicit postsynaptic complex-spike bursting and does not induce LTP at ventral SC synapses. Moreover, EPSP-spike coupling, a process that strongly influences information transfer at synapses, is weaker in ventral pyramidal cells. Our results indicate that all these differences in postsynaptic function are due to an enhanced activation of SK-type K+ channels that suppresses NMDAR-dependent EPSP amplification at ventral SC synapses. Consistent with this, mRNA levels for the SK3 subunit of SK channels are significantly higher in ventral CA1 pyramidal cells. Together, our findings indicate that a dorsal-ventral difference in SK channel regulation of NMDAR activation has a profound effect on the transmission, processing, and storage of information at SC synapses and thus likely contributes to the distinct roles of the dorsal and ventral hippocampus in different behaviors.SIGNIFICANCE STATEMENT Differences in short- and long-term plasticity at Schaffer collateral (SC) synapses in the dorsal and ventral hippocampus likely contribute importantly to the distinct roles of these regions in cognition and behavior. Although dorsal and ventral CA1 pyramidal cells exhibit markedly different gene expression profiles, how these differences influence plasticity at SC synapses is unclear. Here we report that increased mRNA levels for the SK3 subunit of SK-type K+ channels in ventral pyramidal cells is associated with an enhanced activation of SK channels that strongly suppresses NMDAR activation at ventral SC synapses. This leads to striking differences in multiple aspects of synaptic transmission at dorsal and ventral SC synapses and underlies the reduced ability of ventral SC synapses to undergo LTP.
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46
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Prince LY, Bacon TJ, Tigaret CM, Mellor JR. Neuromodulation of the Feedforward Dentate Gyrus-CA3 Microcircuit. Front Synaptic Neurosci 2016; 8:32. [PMID: 27799909 PMCID: PMC5065980 DOI: 10.3389/fnsyn.2016.00032] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 09/20/2016] [Indexed: 12/16/2022] Open
Abstract
The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on the processes of episodic memory encoding and retrieval.
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Affiliation(s)
- Luke Y Prince
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol Bristol, UK
| | - Travis J Bacon
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol Bristol, UK
| | - Cezar M Tigaret
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol Bristol, UK
| | - Jack R Mellor
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol Bristol, UK
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47
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Jones OD. Do group I metabotropic glutamate receptors mediate LTD? Neurobiol Learn Mem 2016; 138:85-97. [PMID: 27545442 DOI: 10.1016/j.nlm.2016.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/01/2016] [Accepted: 08/17/2016] [Indexed: 01/31/2023]
Abstract
Synapses undergo significant structural and functional reorganization in response to varying patterns of stimulation. These forms of plasticity are considered fundamental to cognition and neuronal homeostasis. An increasing number of reports highlight the importance of activity-dependent synaptic strengthening (long term potentiation: LTP) for learning. However, the functional significance of activity-dependent weakening of synapses (long term depression: LTD) remains relatively poorly understood. One form of synaptic weakening, induced by group I metabotropic glutamate receptors (mGluRs), has received significant attention from a mechanistic point of view and because of its augmentation in a murine model of Fragile X Syndrome. Yet, studies of this form of plasticity often yield confusing, contradictory results. These conflicting findings are likely attributable to the bulk stimulation and recording techniques often used to study synaptic plasticity (typically involving evoked extracellular recordings, which represent the summed activity of many synapses). Such studies inherently blur the identity of the synapses undergoing change, thus giving the illusion that synapses per se are being modified when in fact this may only be true of a specific subset of synapses. Indeed, studies employing minimal synaptic activation paint a fundamentally different picture of what is commonly called "mGluR-LTD". Here, I review the evidence in favour of group I mGluRs as mediators of various forms of synaptic downregulation and attempt to explain discrepancies in the literature. I argue that, while multiple forms of synaptic weakening may be triggered by these receptors, the canonical form of group I mGluR-mediated depression, mGluR-LTD, is in fact not a depression of basal synaptic responses. Rather, it is a reversal of established LTP and thus a form of depotentiation. Far from being arbitrary, this distinction has significant implications for the role of group I mGluRs in cognition, both in the healthy brain and in pathological conditions. Further, the differential actions of group I mGluRs at naïve and potentiated synapses suggest these receptors signal in a state-dependent manner to regulate various stages of the learning process.
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Affiliation(s)
- Owen D Jones
- Department of Psychology, Brain Health Research Centre & Brain Research New Zealand, University of Otago, Dunedin, New Zealand.
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48
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Luu P, Essaki Arumugam EM, Anderson E, Gunn A, Rech D, Turovets S, Tucker DM. Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling. Front Hum Neurosci 2016. [PMID: 27531976 DOI: 10.3339/fnhum.2016.00377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual's cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling.
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Affiliation(s)
- Phan Luu
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
| | | | | | | | | | - Sergei Turovets
- Electrical Geodesics, Inc., EugeneOR, USA; NeuroInformatics Center, University of Oregon, EugeneOR, USA
| | - Don M Tucker
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
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49
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Luu P, Essaki Arumugam EM, Anderson E, Gunn A, Rech D, Turovets S, Tucker DM. Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling. Front Hum Neurosci 2016; 10:377. [PMID: 27531976 PMCID: PMC4969286 DOI: 10.3389/fnhum.2016.00377] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 07/12/2016] [Indexed: 12/16/2022] Open
Abstract
In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual's cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling.
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Affiliation(s)
- Phan Luu
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
| | | | | | | | | | - Sergei Turovets
- Electrical Geodesics, Inc., EugeneOR, USA; NeuroInformatics Center, University of Oregon, EugeneOR, USA
| | - Don M Tucker
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
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Jedlicka P, Deller T. Understanding the role of synaptopodin and the spine apparatus in Hebbian synaptic plasticity - New perspectives and the need for computational modeling. Neurobiol Learn Mem 2016; 138:21-30. [PMID: 27470091 DOI: 10.1016/j.nlm.2016.07.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/15/2016] [Accepted: 07/23/2016] [Indexed: 12/17/2022]
Abstract
Synaptopodin (SP) is a proline-rich actin-associated protein essential for the formation of a spine apparatus (SA) in dendritic spines. The SA consists of stacks of smooth endoplasmic reticulum (sER) contiguous with the meshwork of somatodendritic ER. Spines of SP-deficient mice contain sER but no SA, demonstrating that SP is necessary for the assembly of ER cisterns into the more complex SA organelle. Although the SA was described decades ago, its function was difficult to investigate and remained elusive, in part because reliable markers for the SA were missing. After SP was identified as an essential component and a reliable marker of the SA, a role of SP/SA in hippocampal synaptic plasticity could be firmly established using loss-of-function approaches. Further studies revealed that SP/SA participate in the regulation of Ca2+-dependent spine-specific Hebbian plasticity and in activity-dependent changes in the spine actin cytoskeleton. In this review we are summarizing recent progress made on SP/SA in Hebbian plasticity and discuss open questions such as causality, spatiotemporal dynamics and complementarity of SP/SA-dependent mechanisms. We are proposing that computational modeling of spine Ca2+-signaling and actin remodeling pathways could address some of these issues and could indicate future research directions. Moreover, reaction-diffusion simulations could help to identify key feedforward and feedback regulatory motifs regulating the switch between an LTP and an LTD signaling module in SP/SA-containing spines, thus helping to find a unified view of SP/SA action in Hebbian plasticity.
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Affiliation(s)
- Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, D-60590 Frankfurt/Main, Germany.
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, D-60590 Frankfurt/Main, Germany.
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