1
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Papenberg G, Karalija N, Johansson J, Andersson M, Axelsson J, Riklund K, Lindenberger U, Nyberg L, Bäckman L. The influence of hippocampal dopamine D2 receptor losses on episodic-memory decline across 5 years is moderated by BDNF and KIBRA polymorphisms. Cortex 2024; 176:53-61. [PMID: 38749085 DOI: 10.1016/j.cortex.2024.01.014] [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: 12/27/2022] [Revised: 12/01/2023] [Accepted: 01/16/2024] [Indexed: 06/11/2024]
Abstract
Losses in dopamine (DA) functioning may contribute to aging-related decline in cognition. Hippocampal DA is necessary for successful episodic memory formation. Previously, we reported that higher DA D2 receptor (D2DR) availability in hippocampus is beneficial for episodic memory only in older carriers of more advantageous genotypes of well-established plasticity-related genetic variations, the brain-derived neurotrophic factor (BDNF, rs6265) and the kidney and brain expressed protein (KIBRA, rs17070145) polymorphisms. Extending our observations to the longitudinal level, the current data show that individuals with one or no beneficial BDNF and KIBRA genotype (n = 80) decline more in episodic memory across five years, without any contribution of losses in hippocampal D2DR availability to memory decline. Although carriers of two beneficial genotypes (n = 39) did not decline overall in episodic memory, losses of hippocampal D2DR availability were predictive of episodic-memory decline among these individuals. Our findings have implications for interventions targeting DA modulation to enhance episodic memory in aging, which may not benefit all older individuals.
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Affiliation(s)
- Goran Papenberg
- Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
| | - Nina Karalija
- Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden; Department of Medical and Translational Biology, Umeå University, Umeå, Sweden
| | - Jarkko Johansson
- Department of Diagnostics and Intervention, Umeå University, Umeå, Sweden; Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden
| | - Micael Andersson
- Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden; Department of Medical and Translational Biology, Umeå University, Umeå, Sweden
| | - Jan Axelsson
- Department of Diagnostics and Intervention, Umeå University, Umeå, Sweden; Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden
| | - Katrine Riklund
- Department of Diagnostics and Intervention, Umeå University, Umeå, Sweden; Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden
| | - Ulman Lindenberger
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany; Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin, Germany
| | - Lars Nyberg
- Department of Diagnostics and Intervention, Umeå University, Umeå, Sweden; Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden; Department of Medical and Translational Biology, Umeå University, Umeå, Sweden
| | - Lars Bäckman
- Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden
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2
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Sayegh FJP, Mouledous L, Macri C, Pi Macedo J, Lejards C, Rampon C, Verret L, Dahan L. Ventral tegmental area dopamine projections to the hippocampus trigger long-term potentiation and contextual learning. Nat Commun 2024; 15:4100. [PMID: 38773091 PMCID: PMC11109191 DOI: 10.1038/s41467-024-47481-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 03/28/2024] [Indexed: 05/23/2024] Open
Abstract
In most models of neuronal plasticity and memory, dopamine is thought to promote the long-term maintenance of Long-Term Potentiation (LTP) underlying memory processes, but not the initiation of plasticity or new information storage. Here, we used optogenetic manipulation of midbrain dopamine neurons in male DAT::Cre mice, and discovered that stimulating the Schaffer collaterals - the glutamatergic axons connecting CA3 and CA1 regions - of the dorsal hippocampus concomitantly with midbrain dopamine terminals within a 200 millisecond time-window triggers LTP at glutamatergic synapses. Moreover, we showed that the stimulation of this dopaminergic pathway facilitates contextual learning in awake behaving mice, while its inhibition hinders it. Thus, activation of midbrain dopamine can operate as a teaching signal that triggers NeoHebbian LTP and promotes supervised learning.
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Affiliation(s)
- Fares J P Sayegh
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France.
| | - Lionel Mouledous
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France
| | - Catherine Macri
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France
| | - Juliana Pi Macedo
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France
| | - Camille Lejards
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France
| | - Claire Rampon
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France
| | - Laure Verret
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France
| | - Lionel Dahan
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse, France.
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3
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Tse D, Privitera L, Norton AC, Gobbo F, Spooner P, Takeuchi T, Martin SJ, Morris RGM. Cell-type-specific optogenetic stimulation of the locus coeruleus induces slow-onset potentiation and enhances everyday memory in rats. Proc Natl Acad Sci U S A 2023; 120:e2307275120. [PMID: 37931094 PMCID: PMC10655220 DOI: 10.1073/pnas.2307275120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 09/12/2023] [Indexed: 11/08/2023] Open
Abstract
Memory formation is typically divided into phases associated with encoding, storage, consolidation, and retrieval. The neural determinants of these phases are thought to differ. This study first investigated the impact of the experience of novelty in rats incurred at a different time, before or after, the precise moment of memory encoding. Memory retention was enhanced. Optogenetic activation of the locus coeruleus mimicked this enhancement induced by novelty, both when given before and after the moment of encoding. Optogenetic activation of the locus coeruleus also induced a slow-onset potentiation of field potentials in area CA1 of the hippocampus evoked by CA3 stimulation. Despite the locus coeruleus being considered a primarily noradrenergic area, both effects of such stimulation were blocked by the dopamine D1/D5 receptor antagonist SCH 23390. These findings substantiate and enrich the evidence implicating the locus coeruleus in cellular aspects of memory consolidation in hippocampus.
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Affiliation(s)
- Dorothy Tse
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
- Department of Psychology, Edge Hill University, OmskirkL39 4QP, United Kingdom
| | - Lucia Privitera
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
- School of Systems Medicine, University of Dundee, DundeeDD1 4HN, United Kingdom
- Barts and the London School of Medicine, Institute of Health Sciences Education, Queen Mary University of London Malta Campus, VictoriaVCT 2570, Malta
| | - Anna C. Norton
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
| | - Francesco Gobbo
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
| | - Patrick Spooner
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
| | - Tomonori Takeuchi
- Danish Research Institute of Translational Neuroscience, Nordic-European Molecular Biology Laboratory Partnership for Molecular Medicine, Aarhus University, Aarhus8000, Denmark
- Center for Proteins in Memory, Danish National Research Foundation, Department of Biomedicine, Aarhus University, Aarhus8000, Denmark
| | - Stephen J. Martin
- School of Systems Medicine, University of Dundee, DundeeDD1 4HN, United Kingdom
| | - Richard G. M. Morris
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
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4
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de Sousa AF, Chowdhury A, Silva AJ. Dimensions and mechanisms of memory organization. Neuron 2021; 109:2649-2662. [PMID: 34242564 PMCID: PMC8416710 DOI: 10.1016/j.neuron.2021.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/17/2021] [Accepted: 06/11/2021] [Indexed: 12/31/2022]
Abstract
Memory formation is dynamic in nature, and acquisition of new information is often influenced by previous experiences. Memories sharing certain attributes are known to interact so that retrieval of one increases the likelihood of retrieving the other, raising the possibility that related memories are organized into associative mnemonic structures of interconnected representations. Although the formation and retrieval of single memories have been studied extensively, very little is known about the brain mechanisms that organize and link related memories. Here we review studies that suggest the existence of mnemonic structures in humans and animal models. These studies suggest three main dimensions of experience that can serve to organize related memories: time, space, and perceptual/conceptual similarities. We propose potential molecular, cellular, and systems mechanisms that might support organization of memories according to these dimensions.
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Affiliation(s)
- André F de Sousa
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ananya Chowdhury
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Alcino J Silva
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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5
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Bin Ibrahim MZ, Benoy A, Sajikumar S. Long-term plasticity in the hippocampus: maintaining within and 'tagging' between synapses. FEBS J 2021; 289:2176-2201. [PMID: 34109726 DOI: 10.1111/febs.16065] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/15/2021] [Accepted: 06/01/2021] [Indexed: 12/11/2022]
Abstract
Synapses between neurons are malleable biochemical structures, strengthening and diminishing over time dependent on the type of information they receive. This phenomenon known as synaptic plasticity underlies learning and memory, and its different forms, long-term potentiation (LTP) and long-term depression (LTD), perform varied cognitive roles in reinforcement, relearning and associating memories. Moreover, both LTP and LTD can exist in an early transient form (early-LTP/LTD) or a late persistent form (late-LTP/LTD), which are triggered by different induction protocols, and also differ in their dependence on protein synthesis and the involvement of key molecular players. Beyond homosynaptic modifications, synapses can also interact with one another. This is encapsulated in the synaptic tagging and capture hypothesis (STC), where synapses expressing early-LTP/LTD present a 'tag' that can capture the protein synthesis products generated during a temporally proximal late-LTP/LTD induction. This 'tagging' phenomenon forms the framework of synaptic interactions in various conditions and accounts for the cellular basis of the time-dependent associativity of short-lasting and long-lasting memories. All these synaptic modifications take place under controlled neuronal conditions, regulated by subcellular elements such as epigenetic regulation, proteasomal degradation and neuromodulatory signals. Here, we review current understanding of the different forms of synaptic plasticity and its regulatory mechanisms in the hippocampus, a brain region critical for memory formation. We also discuss expression of plasticity in hippocampal CA2 area, a long-overlooked narrow hippocampal subfield and the behavioural correlate of STC. Lastly, we put forth perspectives for an integrated view of memory representation in synapses.
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Affiliation(s)
- Mohammad Zaki Bin Ibrahim
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Life Sciences Institute Neurobiology Programme, National University of Singapore, Singapore
| | - Amrita Benoy
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Life Sciences Institute Neurobiology Programme, National University of Singapore, Singapore
| | - Sreedharan Sajikumar
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Life Sciences Institute Neurobiology Programme, National University of Singapore, Singapore.,Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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6
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Okuda K, Højgaard K, Privitera L, Bayraktar G, Takeuchi T. Initial memory consolidation and the synaptic tagging and capture hypothesis. Eur J Neurosci 2020; 54:6826-6849. [PMID: 32649022 DOI: 10.1111/ejn.14902] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 06/17/2020] [Accepted: 06/29/2020] [Indexed: 01/05/2023]
Abstract
Everyday memories are retained automatically in the hippocampus and then decay very rapidly. Memory retention can be boosted when novel experiences occur shortly before or shortly after the time of memory encoding via a memory stabilization process called "initial memory consolidation." The dopamine release and new protein synthesis in the hippocampus during a novel experience are crucial for this novelty-induced memory boost. The mechanisms underlying initial memory consolidation are not well-understood, but the synaptic tagging and capture (STC) hypothesis provides a conceptual basis of synaptic plasticity events occurring during initial memory consolidation. In this review, we provide an overview of the STC hypothesis and its relevance to dopaminergic signalling, in order to explore the cellular and molecular mechanisms underlying initial memory consolidation in the hippocampus. We summarize electrophysiological STC processes based on the evidence from two-pathway experiments and a behavioural tagging hypothesis, which translates the STC hypothesis into a related behavioural hypothesis. We also discuss the function of two types of molecules, "synaptic tags" and "plasticity-related proteins," which have a crucial role in the STC process and initial memory consolidation. We describe candidate molecules for the roles of synaptic tag and plasticity-related proteins and interpret their candidacy based on evidence from two-pathway experiments ex vivo, behavioural tagging experiments in vivo and recent cutting-edge optical imaging experiments. Lastly, we discuss the direction of future studies to advance our understanding of molecular mechanisms underlying the STC process, which are critical for initial memory consolidation in the hippocampus.
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Affiliation(s)
- Kosuke Okuda
- Department of Biomedicine, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark
| | - Kristoffer Højgaard
- Department of Biomedicine, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark.,Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus C, Denmark
| | - Lucia Privitera
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,School of Medicine, Ninewells Hospital, University of Dundee, Dundee, UK
| | - Gülberk Bayraktar
- Department of Biomedicine, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark.,Institut für Klinische Neurobiologie, Universitätsklinikum Würzburg, Würzburg, Germany
| | - Tomonori Takeuchi
- Department of Biomedicine, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark
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7
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Haubrich J, Bernabo M, Baker AG, Nader K. Impairments to Consolidation, Reconsolidation, and Long-Term Memory Maintenance Lead to Memory Erasure. Annu Rev Neurosci 2020; 43:297-314. [PMID: 32097575 DOI: 10.1146/annurev-neuro-091319-024636] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An enduring problem in neuroscience is determining whether cases of amnesia result from eradication of the memory trace (storage impairment) or if the trace is present but inaccessible (retrieval impairment). The most direct approach to resolving this question is to quantify changes in the brain mechanisms of long-term memory (BM-LTM). This approach argues that if the amnesia is due to a retrieval failure, BM-LTM should remain at levels comparable to trained, unimpaired animals. Conversely, if memories are erased, BM-LTM should be reduced to resemble untrained levels. Here we review the use of BM-LTM in a number of studies that induced amnesia by targeting memory maintenance or reconsolidation. The literature strongly suggests that such amnesia is due to storage rather than retrieval impairments. We also describe the shortcomings of the purely behavioral protocol that purports to show recovery from amnesia as a method of understanding the nature of amnesia.
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Affiliation(s)
- Josué Haubrich
- Department of Psychology, McGill University, Montreal, Quebec H3A 1B1, Canada;
| | - Matteo Bernabo
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Andrew G Baker
- Department of Psychology, McGill University, Montreal, Quebec H3A 1B1, Canada;
| | - Karim Nader
- Department of Psychology, McGill University, Montreal, Quebec H3A 1B1, Canada;
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8
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Papenberg G, Karalija N, Salami A, Andersson M, Axelsson J, Riklund K, Lindenberger U, Nyberg L, Bäckman L. The Influence of Hippocampal Dopamine D2 Receptors on Episodic Memory Is Modulated by BDNF and KIBRA Polymorphisms. J Cogn Neurosci 2019; 31:1422-1429. [PMID: 31112471 DOI: 10.1162/jocn_a_01429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Episodic memory is a polygenic trait influenced by different molecular mechanisms. We used PET and a candidate gene approach to investigate how individual differences at the molecular level translate into between-person differences in episodic memory performance of elderly persons. Specifically, we examined the interactive effects between hippocampal dopamine D2 receptor (D2DR) availability and candidate genes relevant for hippocampus-related memory functioning. We show that the positive effects of high D2DR availability in the hippocampus on episodic memory are confined to carriers of advantageous genotypes of the brain-derived neurotrophic factor (BDNF, rs6265) and the kidney and brain expressed protein (KIBRA, rs17070145) polymorphisms. By contrast, these polymorphisms did not modulate the positive relationship between caudate D2DR availability and episodic memory.
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Affiliation(s)
| | | | - Alireza Salami
- Karolinska Institute and Stockholm University.,Umeå University
| | | | | | | | - Ulman Lindenberger
- Max Planck Institute for Human Development, Berlin.,Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin and London
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9
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Behavioral tagging: Plausible involvement of PKMζ, Arc and role of neurotransmitter receptor systems. Neurosci Biobehav Rev 2018; 94:210-218. [DOI: 10.1016/j.neubiorev.2018.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 07/13/2018] [Accepted: 07/13/2018] [Indexed: 12/21/2022]
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10
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Recording Field Potentials and Synaptic Plasticity From Freely Behaving Rodents. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2018. [DOI: 10.1016/b978-0-12-812028-6.00001-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Substance P induces plasticity and synaptic tagging/capture in rat hippocampal area CA2. Proc Natl Acad Sci U S A 2017; 114:E8741-E8749. [PMID: 28973908 DOI: 10.1073/pnas.1711267114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The hippocampal area Cornu Ammonis (CA) CA2 is important for social interaction and is innervated by Substance P (SP)-expressing supramammillary (SuM) nucleus neurons. SP exerts neuromodulatory effects on pain processing and central synaptic transmission. Here we provide evidence that SP can induce a slowly developing NMDA receptor- and protein synthesis-dependent potentiation of synaptic transmission that can be induced not only at entorhinal cortical (EC)-CA2 synapses but also at long-term potentiation (LTP)-resistant Schaffer collateral (SC)-CA2 synapses. In addition, SP-induced potentiation of SC-CA2 synapses transforms a short-term potentiation of EC-CA2 synaptic transmission into LTP, consistent with the synaptic tagging and capture hypothesis. Interestingly, this SP-induced potentiation and associative interaction between the EC and SC inputs of CA2 neurons is independent of the GABAergic system. In addition, CaMKIV and PKMζ play a critical role in the SP-induced effects on SC-CA2 and EC-CA2 synapses. Thus, afferents from SuM neurons are ideally situated to prime CA2 synapses for the formation of long-lasting plasticity and associativity.
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12
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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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13
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Leibold C, Monsalve-Mercado MM. Asymmetry of Neuronal Combinatorial Codes Arises from Minimizing Synaptic Weight Change. Neural Comput 2016; 28:1527-52. [PMID: 27348595 DOI: 10.1162/neco_a_00854] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Synaptic change is a costly resource, particularly for brain structures that have a high demand of synaptic plasticity. For example, building memories of object positions requires efficient use of plasticity resources since objects can easily change their location in space and yet we can memorize object locations. But how should a neural circuit ideally be set up to integrate two input streams (object location and identity) in case the overall synaptic changes should be minimized during ongoing learning? This letter provides a theoretical framework on how the two input pathways should ideally be specified. Generally the model predicts that the information-rich pathway should be plastic and encoded sparsely, whereas the pathway conveying less information should be encoded densely and undergo learning only if a neuronal representation of a novel object has to be established. As an example, we consider hippocampal area CA1, which combines place and object information. The model thereby provides a normative account of hippocampal rate remapping, that is, modulations of place field activity by changes of local cues. It may as well be applicable to other brain areas (such as neocortical layer V) that learn combinatorial codes from multiple input streams.
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Affiliation(s)
- Christian Leibold
- Department Biology II, Ludwig-Maximilians-Universität München, and Bernstein Center for Computational Neuroscience Munich, 82152 Martisreid, Germany
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14
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Tsokas P, Hsieh C, Yao Y, Lesburguères E, Wallace EJC, Tcherepanov A, Jothianandan D, Hartley BR, Pan L, Rivard B, Farese RV, Sajan MP, Bergold PJ, Hernández AI, Cottrell JE, Shouval HZ, Fenton AA, Sacktor TC. Compensation for PKMζ in long-term potentiation and spatial long-term memory in mutant mice. eLife 2016; 5. [PMID: 27187150 PMCID: PMC4869915 DOI: 10.7554/elife.14846] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/23/2016] [Indexed: 02/07/2023] Open
Abstract
PKMζ is a persistently active PKC isoform proposed to maintain late-LTP and long-term memory. But late-LTP and memory are maintained without PKMζ in PKMζ-null mice. Two hypotheses can account for these findings. First, PKMζ is unimportant for LTP or memory. Second, PKMζ is essential for late-LTP and long-term memory in wild-type mice, and PKMζ-null mice recruit compensatory mechanisms. We find that whereas PKMζ persistently increases in LTP maintenance in wild-type mice, PKCι/λ, a gene-product closely related to PKMζ, persistently increases in LTP maintenance in PKMζ-null mice. Using a pharmacogenetic approach, we find PKMζ-antisense in hippocampus blocks late-LTP and spatial long-term memory in wild-type mice, but not in PKMζ-null mice without the target mRNA. Conversely, a PKCι/λ-antagonist disrupts late-LTP and spatial memory in PKMζ-null mice but not in wild-type mice. Thus, whereas PKMζ is essential for wild-type LTP and long-term memory, persistent PKCι/λ activation compensates for PKMζ loss in PKMζ-null mice. DOI:http://dx.doi.org/10.7554/eLife.14846.001 How are long-term memories stored in the brain? The formation of memories is believed to depend on the strengthening of connections between neurons. During learning, neurons produce an enzyme called PKMzeta (or PKMζ), which is thought to be responsible for maintaining the newly strengthened connections. Inhibitors of PKMzeta, such as a drug called ZIP, disrupt long-term memories. This suggests that the brain may be like a computer hard disc in that its stored information — its memories — could be erased. However, recent experiments on genetically engineered mice have thrown the role of PKMzeta into question. Knockout mice that lack the gene for PKMzeta can still strengthen connections between neurons and can still learn and remember. Moreover, ZIP still works to reverse the strengthening and to erase long-term memories. This indicates that ZIP can act on something other than the PKMzeta enzyme. These results have led many neuroscientists to doubt that PKMzeta has anything to do with memory. Yet there are two possible explanations for the normal memory in PKMzeta knockout mice. First, PKMzeta is not required for memory, so getting rid of it has no effect. Second, PKMzeta is essential for long-term memory in normal mice. However, knockout mice recruit a back-up mechanism for long-term memory storage, which is also sensitive to the effects of ZIP. To test these possibilities, Tsokas et al. used a modified piece of DNA that prevents neurons with the gene for PKMzeta from producing the enzyme. The DNA blocked memory formation in normal mice, consistent with a role for PKMzeta in memory. However, it had no effect in knockout mice — the DNA had nothing to work on. This suggests that another molecule does indeed act as a back-up for PKMzeta in these animals. Further experiments revealed that an enzyme closely related to PKMzeta, called PKCiota/lambda (PKCι/λ), substitutes for PKMzeta during memory storage in the knockout mice. These findings restore PKMzeta to its early promise. They show that PKMzeta is crucial for long-term memory in normal mice, but that something as important as memory storage has a back-up mechanism should PKMzeta fail. Future work may reveal when and how this back-up becomes engaged. DOI:http://dx.doi.org/10.7554/eLife.14846.002
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Affiliation(s)
- Panayiotis Tsokas
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States.,Department of Anesthesiology, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Changchi Hsieh
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Yudong Yao
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | | | - Emma Jane Claire Wallace
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Andrew Tcherepanov
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Desingarao Jothianandan
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Benjamin Rush Hartley
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Ling Pan
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Bruno Rivard
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Robert V Farese
- Department of Internal Medicine, James A Haley Veterans Hospital, University of South Florida, Tampa, United States
| | - Mini P Sajan
- Department of Internal Medicine, James A Haley Veterans Hospital, University of South Florida, Tampa, United States
| | - Peter John Bergold
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Alejandro Iván Hernández
- Department of Pathology, State University of New York Downstate Medical Center, Brooklyn, United States
| | - James E Cottrell
- Department of Anesthesiology, State University of New York Downstate Medical Center, Brooklyn, United States
| | - Harel Z Shouval
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, United States
| | - André Antonio Fenton
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States.,Center for Neural Science, New York University, New York, United States
| | - Todd Charlton Sacktor
- Department of Physiology and Pharmacology, The Robert F Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, United States.,Department of Anesthesiology, State University of New York Downstate Medical Center, Brooklyn, United States.,Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, United States
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15
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Shivarama Shetty M, Gopinadhan S, Sajikumar S. Dopamine D1/D5 receptor signaling regulates synaptic cooperation and competition in hippocampal CA1 pyramidal neurons via sustained ERK1/2 activation. Hippocampus 2015; 26:137-50. [PMID: 26194339 PMCID: PMC5054950 DOI: 10.1002/hipo.22497] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/16/2015] [Indexed: 12/30/2022]
Abstract
Synaptic cooperation and competition are important components of synaptic plasticity that tune synapses for the formation of associative long‐term plasticity, a cellular correlate of associative long‐term memory. We have recently reported that coincidental activation of weak synapses within the vicinity of potentiated synapses will alter the cooperative state of synapses to a competitive state thus leading to the slow decay of long‐term plasticity, but the molecular mechanism underlying this is still unknown. Here, using acute hippocampal slices of rats, we have examined how increasing extracellular dopamine concentrations interact and/or affect electrically induced long‐term potentiation (LTP) in the neighboring synapses. We demonstrate that D1/D5‐receptor‐mediated potentiation at the CA1 Schaffer collateral synapses differentially regulates synaptic co‐operation and competition. Further investigating the molecular players involved, we reveal an important role for extracellular signal‐regulated kinases‐1 and 2 (ERK1/2) as signal integrators and dose‐sensors. Interestingly, a sustained activation of ERK1/2 pathway seems to be involved in the differential regulation of synaptic associativity. The concentration‐dependent effects of the modulatory transmitter, as demonstrated for dopaminergic signaling in the present study, might offer additional computational power by fine tuning synaptic associativity processes for establishing long‐term associative memory in neural networks. © 2015 The Authors Hippocampus Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Mahesh Shivarama Shetty
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Neurobiology/Aging Program, Life Sciences Institute (LSI), National University of Singapore, Singapore
| | - Suma Gopinadhan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Sreedharan Sajikumar
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Neurobiology/Aging Program, Life Sciences Institute (LSI), National University of Singapore, Singapore
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16
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O'Dell TJ, Connor SA, Guglietta R, Nguyen PV. β-Adrenergic receptor signaling and modulation of long-term potentiation in the mammalian hippocampus. ACTA ACUST UNITED AC 2015; 22:461-71. [PMID: 26286656 PMCID: PMC4561407 DOI: 10.1101/lm.031088.113] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/02/2015] [Indexed: 02/06/2023]
Abstract
Encoding new information in the brain requires changes in synaptic strength. Neuromodulatory transmitters can facilitate synaptic plasticity by modifying the actions and expression of specific signaling cascades, transmitter receptors and their associated signaling complexes, genes, and effector proteins. One critical neuromodulator in the mammalian brain is norepinephrine (NE), which regulates multiple brain functions such as attention, perception, arousal, sleep, learning, and memory. The mammalian hippocampus receives noradrenergic innervation and hippocampal neurons express β-adrenergic receptors, which are known to play important roles in gating the induction of long-lasting forms of synaptic potentiation. These forms of long-term potentiation (LTP) are believed to importantly contribute to long-term storage of spatial and contextual memories in the brain. In this review, we highlight the contributions of noradrenergic signaling in general and β-adrenergic receptors in particular, toward modulating hippocampal LTP. We focus on the roles of NE and β-adrenergic receptors in altering the efficacies of specific signaling molecules such as NMDA and AMPA receptors, protein phosphatases, and translation initiation factors. Also, the roles of β-adrenergic receptors in regulating synaptic "tagging" and "capture" of LTP within synaptic networks of the hippocampus are reviewed. Understanding the molecular and cellular bases of noradrenergic signaling will enrich our grasp of how the brain makes new, enduring memories, and may shed light on credible strategies for improving mental health through treatment of specific disorders linked to perturbed memory processing and dysfunctional noradrenergic synaptic transmission.
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Affiliation(s)
- Thomas J O'Dell
- Department of Physiology, David Geffen School of Medicine and Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Steven A Connor
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
| | - Ryan Guglietta
- Interdepartmental Ph.D. Program for Neuroscience, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Peter V Nguyen
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada Department of Psychiatry, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada Department of Neuroscience & Mental Health Institute, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
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17
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David O, Barrera I, Chinnakkaruppan A, Kaphzan H, Nakazawa T, Yamamoto T, Rosenblum K. Dopamine-induced tyrosine phosphorylation of NR2B (Tyr1472) is essential for ERK1/2 activation and processing of novel taste information. Front Mol Neurosci 2014; 7:66. [PMID: 25100942 PMCID: PMC4103512 DOI: 10.3389/fnmol.2014.00066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/02/2014] [Indexed: 01/14/2023] Open
Abstract
Understanding the heterosynaptic interaction between glutamatergic and neuromodulatory synapses is highly important for revealing brain function in health and disease. For instance, the interaction between dopamine and glutamate neurotransmission is vital for memory and synaptic plasticity consolidation, and it is known to converge on extracellular signal-regulated kinase (ERK)-MAPK signaling in neurons. Previous studies suggest that dopamine induces N-methyl-D-aspartate (NMDA) receptor phosphorylation at the NR2B Y1472 subunit, influencing receptor internalization at the synaptic plasma membrane. However, it is unclear whether this phosphorylation is upstream to and/or necessary for ERK1/2 activation, which is known to be crucial for synaptic plasticity and memory consolidation. Here, we tested the hypothesis that tyrosine phosphorylation of NR2B at Y1472 is correlated with ERK1/2 activation by dopamine and necessary for it as well. We find that dopamine receptor D1, but not D2, activates ERK1/2 and leads to NR2BY1472 phosphorylation in the mature hippocampus and cortex. Moreover, our results indicate that NR2B Y1472 phosphorylation is necessary for ERK1/2 activation. Importantly, application of dopamine or the D1 receptor agonist SKF38393 to hippocampal slices from NR2B F1472 mutant mice did not result in ERK1/2 activation, suggesting this site is not only correlated with ERK1/2 activation by dopamine stimulation, but also necessary for it. In addition, NR2B F1472 mice show impairment in learning of attenuation of taste neophobia but not associative taste learning. Our study shows that the dopaminergic and glutamatergic transmission converge on the NMDA receptor itself, at the Y1472 site of the NR2B subunit, and that this convergence is essential for ERK1/2 activation in the mature brain and for processing new sensory information in the cortex.
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Affiliation(s)
- Orit David
- Sagol Department of Neurobiology, University of Haifa Haifa, Israel
| | - Iliana Barrera
- Sagol Department of Neurobiology, University of Haifa Haifa, Israel
| | | | - Hanoch Kaphzan
- Sagol Department of Neurobiology, University of Haifa Haifa, Israel
| | - Takanobu Nakazawa
- Division of Oncology, Institute of Medical Science, University of Tokyo Tokyo, Japan
| | - Tadashi Yamamoto
- Division of Oncology, Institute of Medical Science, University of Tokyo Tokyo, Japan
| | - Kobi Rosenblum
- Sagol Department of Neurobiology, University of Haifa Haifa, Israel ; Center for Gene Manipulation in the Brain, University of Haifa Haifa, Israel
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18
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Up-regulation of PKMζ expression in the anterior cingulate cortex following experimental tooth movement in rats. Arch Oral Biol 2014; 59:749-55. [DOI: 10.1016/j.archoralbio.2014.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 02/27/2014] [Accepted: 04/08/2014] [Indexed: 01/11/2023]
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19
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Hansen N, Manahan-Vaughan D. Dopamine D1/D5 receptors mediate informational saliency that promotes persistent hippocampal long-term plasticity. Cereb Cortex 2014; 24:845-58. [PMID: 23183712 PMCID: PMC3948488 DOI: 10.1093/cercor/bhs362] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Dopamine (DA) plays an essential role in the enablement of cognition. It adds color to experience-dependent information storage, conferring salience to the memories that result. At the synaptic level, experience-dependent information storage is enabled by synaptic plasticity, and given its importance for memory formation, it is not surprising that DA comprises a key neuromodulator in the enablement of synaptic plasticity, and particularly of plasticity that persists for longer periods of time: Analogous to long-term memory. The hippocampus, that is a critical structure for the synaptic processing of semantic, episodic, spatial, and declarative memories, is specifically affected by DA, with the D1/D5 receptor proving crucial for hippocampus-dependent memory. Furthermore, D1/D5 receptors are pivotal in conferring the properties of novelty and reward to information being processed by the hippocampus. They also facilitate the expression of persistent forms of synaptic plasticity, and given reports that both long-term potentiation and long-term depression encode different aspects of spatial representations, this suggests that D1/D5 receptors can drive the nature and qualitative content of stored information in the hippocampus. In light of these observations, we propose that D1/D5 receptors gate hippocampal long-term plasticity and memory and are pivotal in conferring the properties of novelty and reward to information being processed by the hippocampus.
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Affiliation(s)
| | - Denise Manahan-Vaughan
- Department of Neurophysiology, Medical Faculty,Ruhr University Bochum, 44780 Bochum, Germany
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20
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Navakkode S, Korte M. Pharmacological activation of CB1 receptor modulates long term potentiation by interfering with protein synthesis. Neuropharmacology 2014; 79:525-33. [PMID: 24412673 DOI: 10.1016/j.neuropharm.2013.11.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 11/04/2013] [Accepted: 11/21/2013] [Indexed: 12/30/2022]
Abstract
Cognitive impairment is one of the most important side effects associated with cannabis drug abuse, as well as the serious issue concerning the therapeutic use of cannabinoids. Cognitive impairments and neuropsychiatric symptoms are caused by early synaptic dysfunctions, such as loss of synaptic connections in different brain structures including the hippocampus, a region that is believed to play an important role in certain forms of learning and memory. We report here that metaplastic priming of synapses with a cannabinoid type 1 receptor (CB1 receptor) agonist, WIN55,212-2 (WIN55), significantly impaired long-term potentiation in the apical dendrites of CA1 pyramidal neurons. Interestingly, the CB1 receptor exerts its effect by altering the balance of protein synthesis machinery towards higher protein production. Therefore the activation of CB1 receptor, prior to strong tetanization, increased the propensity to produce new proteins. In addition, WIN55 priming resulted in the expression of late-LTP in a synaptic input that would have normally expressed early-LTP, thus confirming that WIN55 priming of LTP induces new synthesis of plasticity-related proteins. Furthermore, in addition to the effects on protein translation, WIN55 also induced synaptic deficits due to the ability of CB1 receptors to inhibit the release of acetylcholine, mediated by both muscarinic and nicotinic acetylcholine receptors. Taken together this supports the notion that the modulation of cholinergic activity by CB1 receptor activation is one mechanism that regulates the synthesis of plasticity-related proteins.
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Affiliation(s)
- Sheeja Navakkode
- Zoology Institute, Division of Cellular Neurobiology, TU, Braunschweig D-38106 Germany
| | - Martin Korte
- Zoology Institute, Division of Cellular Neurobiology, TU, Braunschweig D-38106 Germany.
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21
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Zhang H, Chen G, Kuang H, Tsien JZ. Mapping and deciphering neural codes of NMDA receptor-dependent fear memory engrams in the hippocampus. PLoS One 2013; 8:e79454. [PMID: 24302990 PMCID: PMC3841182 DOI: 10.1371/journal.pone.0079454] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 10/01/2013] [Indexed: 11/27/2022] Open
Abstract
Mapping and decoding brain activity patterns underlying learning and memory represents both great interest and immense challenge. At present, very little is known regarding many of the very basic questions regarding the neural codes of memory: are fear memories retrieved during the freezing state or non-freezing state of the animals? How do individual memory traces give arise to a holistic, real-time associative memory engram? How are memory codes regulated by synaptic plasticity? Here, by applying high-density electrode arrays and dimensionality-reduction decoding algorithms, we investigate hippocampal CA1 activity patterns of trace fear conditioning memory code in inducible NMDA receptor knockout mice and their control littermates. Our analyses showed that the conditioned tone (CS) and unconditioned foot-shock (US) can evoke hippocampal ensemble responses in control and mutant mice. Yet, temporal formats and contents of CA1 fear memory engrams differ significantly between the genotypes. The mutant mice with disabled NMDA receptor plasticity failed to generate CS-to-US or US-to-CS associative memory traces. Moreover, the mutant CA1 region lacked memory traces for “what at when” information that predicts the timing relationship between the conditioned tone and the foot shock. The degraded associative fear memory engram is further manifested in its lack of intertwined and alternating temporal association between CS and US memory traces that are characteristic to the holistic memory recall in the wild-type animals. Therefore, our study has decoded real-time memory contents, timing relationship between CS and US, and temporal organizing patterns of fear memory engrams and demonstrated how hippocampal memory codes are regulated by NMDA receptor synaptic plasticity.
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Affiliation(s)
- Hongmiao Zhang
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Georgia Regents University, Augusta, Georgia, United States of America
| | - Guifen Chen
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Georgia Regents University, Augusta, Georgia, United States of America
| | - Hui Kuang
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Georgia Regents University, Augusta, Georgia, United States of America
- Brain Decoding Center, Banna Biomedical Research Institute, Xi-Shuang-Ban-Na Prefecture, Yunnan Province, China
| | - Joe Z. Tsien
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Georgia Regents University, Augusta, Georgia, United States of America
- * E-mail:
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22
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Hawkins RD. Possible contributions of a novel form of synaptic plasticity in Aplysia to reward, memory, and their dysfunctions in mammalian brain. Learn Mem 2013; 20:580-91. [PMID: 24049187 PMCID: PMC3768196 DOI: 10.1101/lm.031237.113] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Recent studies in Aplysia have identified a new variation of synaptic plasticity in which modulatory transmitters enhance spontaneous release of glutamate, which then acts on postsynaptic receptors to recruit mechanisms of intermediate- and long-term plasticity. In this review I suggest the hypothesis that similar plasticity occurs in mammals, where it may contribute to reward, memory, and their dysfunctions in several psychiatric disorders. In Aplysia, spontaneous release is enhanced by activation of presynaptic serotonin receptors, but presynaptic D1 dopamine receptors or nicotinic acetylcholine receptors could play a similar role in mammals. Those receptors enhance spontaneous release of glutamate in hippocampus, entorhinal cortex, prefrontal cortex, ventral tegmental area, and nucleus accumbens. In all of those brain areas, glutamate can activate postsynaptic receptors to elevate Ca2+ and engage mechanisms of early-phase long-term potentiation (LTP), including AMPA receptor insertion, and of late-phase LTP, including protein synthesis and growth. Thus, presynaptic receptors and spontaneous release may contribute to postsynaptic mechanisms of plasticity in brain regions involved in reward and memory, and could play roles in disorders that affect plasticity in those regions, including addiction, Alzheimer’s disease, schizophrenia, and attention deficit hyperactivity disorder (ADHD).
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Affiliation(s)
- Robert D Hawkins
- Department of Neuroscience, Columbia University, New York, New York 10032, USA
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23
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Abstract
Over more than a century of research has established the fact that sleep benefits the retention of memory. In this review we aim to comprehensively cover the field of "sleep and memory" research by providing a historical perspective on concepts and a discussion of more recent key findings. Whereas initial theories posed a passive role for sleep enhancing memories by protecting them from interfering stimuli, current theories highlight an active role for sleep in which memories undergo a process of system consolidation during sleep. Whereas older research concentrated on the role of rapid-eye-movement (REM) sleep, recent work has revealed the importance of slow-wave sleep (SWS) for memory consolidation and also enlightened some of the underlying electrophysiological, neurochemical, and genetic mechanisms, as well as developmental aspects in these processes. Specifically, newer findings characterize sleep as a brain state optimizing memory consolidation, in opposition to the waking brain being optimized for encoding of memories. Consolidation originates from reactivation of recently encoded neuronal memory representations, which occur during SWS and transform respective representations for integration into long-term memory. Ensuing REM sleep may stabilize transformed memories. While elaborated with respect to hippocampus-dependent memories, the concept of an active redistribution of memory representations from networks serving as temporary store into long-term stores might hold also for non-hippocampus-dependent memory, and even for nonneuronal, i.e., immunological memories, giving rise to the idea that the offline consolidation of memory during sleep represents a principle of long-term memory formation established in quite different physiological systems.
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Affiliation(s)
- Björn Rasch
- Division of Biopsychology, Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland.
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24
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Long-lasting LTP requires neither repeated trains for its induction nor protein synthesis for its development. PLoS One 2012; 7:e40823. [PMID: 22792408 PMCID: PMC3394721 DOI: 10.1371/journal.pone.0040823] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 06/13/2012] [Indexed: 12/29/2022] Open
Abstract
Current thinking about LTP triggered in the area CA1 of hippocampal slices is ruled by two “dogmas”: (1) A single train of high-frequency stimulation is sufficient to trigger short-lasting LTP (1 – 3 h), whereas multiple trains are required to induce long-lasting LTP (L-LTP, more than 4 h). (2) The development of the late phase of L-LTP requires the synthesis of new proteins. In this study, we found that a single high-frequency train could trigger an LTP lasting more than 8 h that was not affected by either anisomycin or cycloheximide (two inhibitors of protein synthesis). We ascertained that the induction of this L-LTP made use of the same mechanisms as those usually reported to be involved in LTP induction: it was dependent on NMDA receptors and on the activation of two “core” kinases, CaMKII and PI3K. These findings call into question the two “dogmas” about LTP.
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25
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Navakkode S, Sajikumar S, Korte M, Soong TW. Dopamine induces LTP differentially in apical and basal dendrites through BDNF and voltage-dependent calcium channels. Learn Mem 2012; 19:294-9. [DOI: 10.1101/lm.026203.112] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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26
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Kandaswamy R, McQuillin A, Curtis D, Gurling H. Tests of linkage and allelic association between markers in the 1p36 PRKCZ (protein kinase C zeta) gene region and bipolar affective disorder. Am J Med Genet B Neuropsychiatr Genet 2012; 159B:201-9. [PMID: 22231931 DOI: 10.1002/ajmg.b.32014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 12/05/2011] [Indexed: 01/11/2023]
Abstract
Three linkage studies of families with multiple cases of bipolar disorder and/or unipolar affective disorder have confirmed the involvement of the chromosome 1p36 region in the etiology of affective disorders with LOD scores of 2.7, 3.6, and 3.97. We investigated the protein kinase C zeta gene (PRKCZ) as a susceptibility locus for bipolar disorder because it is highly brain expressed and is localized close to the marker D1S243 which was linked to affective disorder in a single large UCL bipolar disorder family with a LOD of 3.1. PRKCZ encodes an unusual type of protein kinase which affects axonal differentiation through Wnt-signaling. We genotyped four microsatellite markers and nine single nucleotide polymorphism (SNP) markers within or near the PRKCZ gene in the UCL case-control sample of 600 bipolar disorder patients and up to 605 supernormal controls. Markers D1S243 and rs3128396 were significantly associated with bipolar disorder (empirical P = 0.037 and P = 0.040, respectively). We also included data from eight SNPs which were genotyped as part of our GWA study on bipolar disorder for association analysis. Tests of haplotypic association found that a haplotype block comprising markers rs3128296, rs2503706, and rs3128309 was associated with bipolar disorder (empirical P = 0.004). A previous linkage study had shown greater evidence for linkage within female cases compared to males. Therefore, to assess if the association was sex-specific, we performed a female-only allelic-association analysis, which resulted in SNPs rs3128296 and rs3128309 becoming associated with bipolar disorder (P = 0.004 and P = 0.016, respectively). PRKCZ may play a role in susceptibility to bipolar affective disorder.
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Affiliation(s)
- Radhika Kandaswamy
- Molecular Psychiatry Laboratory, Research Department of Mental Health Sciences, University College London, UK
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27
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Impairment of catecholamine systems during induction of long-term potentiation at hippocampal CA1 synapses in HPC-1/syntaxin 1A knock-out mice. J Neurosci 2012; 32:381-9. [PMID: 22219298 DOI: 10.1523/jneurosci.2911-11.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The membrane protein HPC-1/syntaxin 1A is believed to play a key role in synaptic vesicle exocytosis, and it was recently suggested to be required for synaptic plasticity. Despite evidence for the function of HPC-1/syntaxin 1A in synaptic plasticity, the underlying cellular mechanism is unclear. We found that although fast synaptic transmission and long-term depression were unaffected, HPC-1/syntaxin 1A knock-out (STX1A(-/-)) mice showed impaired long-term potentiation (LTP) in response to theta-burst stimulation in CA1 hippocampal slices. The impairment in LTP was rescued by the application of forskolin, an adenylyl cyclase activator, or more robust stimulation, suggesting that cAMP/protein kinase A signaling was suppressed in these mice. In addition, catecholamine release from the hippocampus was significantly reduced in STX1A(-/-) mice. Because HPC-1/syntaxin 1A regulates exocytosis of dense-core synaptic vesicles, which contain neuromodulatory transmitters such as noradrenaline, dopamine and 5-HT, we examined the effect of neuromodulatory transmitters on LTP induction. Noradrenaline and dopamine enhanced LTP induction in STX1A(-/-) mice, whereas catecholamine depletion reduced LTP induction in wild-type mice. Theses results suggest that HPC-1/syntaxin 1A regulates catecholaminergic systems via exocytosis of dense-core synaptic vesicles, and that deletion of HPC-1/syntaxin 1A causes impairment of LTP induction.
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Gal-Ben-Ari S, Rosenblum K. Molecular mechanisms underlying memory consolidation of taste information in the cortex. Front Behav Neurosci 2012; 5:87. [PMID: 22319481 PMCID: PMC3251832 DOI: 10.3389/fnbeh.2011.00087] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 12/12/2011] [Indexed: 12/22/2022] Open
Abstract
The senses of taste and odor are both chemical senses. However, whereas an organism can detect an odor at a relatively long distance from its source, taste serves as the ultimate proximate gatekeeper of food intake: it helps in avoiding poisons and consuming beneficial substances. The automatic reaction to a given taste has been developed during evolution and is well adapted to conditions that may occur with high probability during the lifetime of an organism. However, in addition to this automatic reaction, animals can learn and remember tastes, together with their positive or negative values, with high precision and in light of minimal experience. This ability of mammalians to learn and remember tastes has been studied extensively in rodents through application of reasonably simple and well defined behavioral paradigms. The learning process follows a temporal continuum similar to those of other memories: acquisition, consolidation, retrieval, relearning, and reconsolidation. Moreover, inhibiting protein synthesis in the gustatory cortex (GC) specifically affects the consolidation phase of taste memory, i.e., the transformation of short- to long-term memory, in keeping with the general biochemical definition of memory consolidation. This review aims to present a general background of taste learning, and to focus on recent findings regarding the molecular mechanisms underlying taste–memory consolidation in the GC. Specifically, the roles of neurotransmitters, neuromodulators, immediate early genes, and translation regulation are addressed.
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