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Hagena H, Manahan-Vaughan D. Interplay of hippocampal long-term potentiation and long-term depression in enabling memory representations. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230229. [PMID: 38853558 DOI: 10.1098/rstb.2023.0229] [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: 01/08/2024] [Accepted: 05/07/2024] [Indexed: 06/11/2024] Open
Abstract
Hippocampal long-term potentiation (LTP) and long-term depression (LTD) are Hebbian forms of synaptic plasticity that are widely believed to comprise the physiological correlates of associative learning. They comprise a persistent, input-specific increase or decrease, respectively, in synaptic efficacy that, in rodents, can be followed for days and weeks in vivo. Persistent (>24 h) LTP and LTD exhibit distinct frequency-dependencies and molecular profiles in the hippocampal subfields. Moreover, causal and genetic studies in behaving rodents indicate that both LTP and LTD fulfil specific and complementary roles in the acquisition and retention of spatial memory. LTP is likely to be responsible for the generation of a record of spatial experience, which may serve as an associative schema that can be re-used to expedite or facilitate subsequent learning. In contrast, LTD may enable modification and dynamic updating of this representation, such that detailed spatial content information is included and the schema is rendered unique and distinguishable from other similar representations. Together, LTP and LTD engage in a dynamic interplay that supports the generation of complex associative memories that are resistant to generalization. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Hardy Hagena
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum , Bochum 44780, Germany
| | - Denise Manahan-Vaughan
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum , Bochum 44780, Germany
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2
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Rößler N, Smilovic D, Vuksic M, Jedlicka P, Deller T. Maintenance of Lognormal-Like Skewed Dendritic Spine Size Distributions in Dentate Granule Cells of TNF, TNF-R1, TNF-R2, and TNF-R1/2-Deficient Mice. J Comp Neurol 2024; 532:e25645. [PMID: 38943486 DOI: 10.1002/cne.25645] [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: 10/19/2023] [Revised: 03/25/2024] [Accepted: 05/30/2024] [Indexed: 07/01/2024]
Abstract
Dendritic spines are sites of synaptic plasticity and their head size correlates with the strength of the corresponding synapse. We recently showed that the distribution of spine head sizes follows a lognormal-like distribution even after blockage of activity or plasticity induction. As the cytokine tumor necrosis factor (TNF) influences synaptic transmission and constitutive TNF and receptor (TNF-R)-deficiencies cause changes in spine head size distributions, we tested whether these genetic alterations disrupt the lognormality of spine head sizes. Furthermore, we distinguished between spines containing the actin-modulating protein synaptopodin (SP-positive), which is present in large, strong and stable spines and those lacking it (SP-negative). Our analysis revealed that neither TNF-deficiency nor the absence of TNF-R1, TNF-R2 or TNF-R 1 and 2 (TNF-R1/R2) degrades the general lognormal-like, skewed distribution of spine head sizes (all spines, SP-positive spines, SP-negative spines). However, TNF, TNF-R1 and TNF-R2-deficiency affected the width of the lognormal distribution, and TNF-R1/2-deficiency shifted the distribution to the left. Our findings demonstrate the robustness of the lognormal-like, skewed distribution, which is maintained even in the face of genetic manipulations that alter the distribution of spine head sizes. Our observations are in line with homeostatic adaptation mechanisms of neurons regulating the distribution of spines and their head sizes.
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MESH Headings
- Animals
- Dendritic Spines/metabolism
- Mice
- Receptors, Tumor Necrosis Factor, Type I/deficiency
- Receptors, Tumor Necrosis Factor, Type I/metabolism
- Receptors, Tumor Necrosis Factor, Type I/genetics
- Mice, Knockout
- Dentate Gyrus/metabolism
- Dentate Gyrus/cytology
- Tumor Necrosis Factor-alpha/metabolism
- Mice, Inbred C57BL
- Receptors, Tumor Necrosis Factor, Type II/deficiency
- Receptors, Tumor Necrosis Factor, Type II/metabolism
- Receptors, Tumor Necrosis Factor, Type II/genetics
- Neurons/metabolism
- Male
- Microfilament Proteins/metabolism
- Microfilament Proteins/genetics
- Microfilament Proteins/deficiency
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Affiliation(s)
- Nina Rößler
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt, Germany
- ICAR3R - Interdisciplinary Centre for 3Rs in Animal Research, Computer-Based Modelling, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Dinko Smilovic
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt, Germany
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Mario Vuksic
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt, Germany
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt, Germany
- ICAR3R - Interdisciplinary Centre for 3Rs in Animal Research, Computer-Based Modelling, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt, Germany
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3
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Samavat M, Bartol TM, Harris KM, Sejnowski TJ. Synaptic Information Storage Capacity Measured With Information Theory. Neural Comput 2024; 36:781-802. [PMID: 38658027 DOI: 10.1162/neco_a_01659] [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: 07/31/2023] [Accepted: 01/02/2024] [Indexed: 04/26/2024]
Abstract
Variation in the strength of synapses can be quantified by measuring the anatomical properties of synapses. Quantifying precision of synaptic plasticity is fundamental to understanding information storage and retrieval in neural circuits. Synapses from the same axon onto the same dendrite have a common history of coactivation, making them ideal candidates for determining the precision of synaptic plasticity based on the similarity of their physical dimensions. Here, the precision and amount of information stored in synapse dimensions were quantified with Shannon information theory, expanding prior analysis that used signal detection theory (Bartol et al., 2015). The two methods were compared using dendritic spine head volumes in the middle of the stratum radiatum of hippocampal area CA1 as well-defined measures of synaptic strength. Information theory delineated the number of distinguishable synaptic strengths based on nonoverlapping bins of dendritic spine head volumes. Shannon entropy was applied to measure synaptic information storage capacity (SISC) and resulted in a lower bound of 4.1 bits and upper bound of 4.59 bits of information based on 24 distinguishable sizes. We further compared the distribution of distinguishable sizes and a uniform distribution using Kullback-Leibler divergence and discovered that there was a nearly uniform distribution of spine head volumes across the sizes, suggesting optimal use of the distinguishable values. Thus, SISC provides a new analytical measure that can be generalized to probe synaptic strengths and capacity for plasticity in different brain regions of different species and among animals raised in different conditions or during learning. How brain diseases and disorders affect the precision of synaptic plasticity can also be probed.
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Affiliation(s)
- Mohammad Samavat
- Department of Electrical and Computer Engineering, Jacobs School of Engineering, University of California, San Diego
- Computational Neurobiology Laboratory, Salk Institute for Biological Sciences, La Jolla, CA 92037, U.S.A.
| | - Thomas M Bartol
- Computational Neurobiology Laboratory, Salk Institute for Biological Sciences, La Jolla, CA 92037, U.S.A.
| | - Kristen M Harris
- Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, U.S.A.
| | - Terrence J Sejnowski
- Computational Neurobiology Laboratory, Salk Institute for Biological Sciences, La Jolla, CA 92037, U.S.A
- Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, U.S.A.
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4
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Cano-Astorga N, Plaza-Alonso S, Turegano-Lopez M, Rodrigo-Rodríguez J, Merchan-Perez A, DeFelipe J. Unambiguous identification of asymmetric and symmetric synapses using volume electron microscopy. Front Neuroanat 2024; 18:1348032. [PMID: 38645671 PMCID: PMC11026665 DOI: 10.3389/fnana.2024.1348032] [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: 12/01/2023] [Accepted: 03/08/2024] [Indexed: 04/23/2024] Open
Abstract
The brain contains thousands of millions of synapses, exhibiting diverse structural, molecular, and functional characteristics. However, synapses can be classified into two primary morphological types: Gray's type I and type II, corresponding to Colonnier's asymmetric (AS) and symmetric (SS) synapses, respectively. AS and SS have a thick and thin postsynaptic density, respectively. In the cerebral cortex, since most AS are excitatory (glutamatergic), and SS are inhibitory (GABAergic), determining the distribution, size, density, and proportion of the two major cortical types of synapses is critical, not only to better understand synaptic organization in terms of connectivity, but also from a functional perspective. However, several technical challenges complicate the study of synapses. Potassium ferrocyanide has been utilized in recent volume electron microscope studies to enhance electron density in cellular membranes. However, identifying synaptic junctions, especially SS, becomes more challenging as the postsynaptic densities become thinner with increasing concentrations of potassium ferrocyanide. Here we describe a protocol employing Focused Ion Beam Milling and Scanning Electron Microscopy for studying brain tissue. The focus is on the unequivocal identification of AS and SS types. To validate SS observed using this protocol as GABAergic, experiments with immunocytochemistry for the vesicular GABA transporter were conducted on fixed mouse brain tissue sections. This material was processed with different concentrations of potassium ferrocyanide, aiming to determine its optimal concentration. We demonstrate that using a low concentration of potassium ferrocyanide (0.1%) improves membrane visualization while allowing unequivocal identification of synapses as AS or SS.
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Affiliation(s)
- Nicolás Cano-Astorga
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- PhD Program in Neuroscience, Autonoma de Madrid University-Cajal Institute, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Sergio Plaza-Alonso
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Turegano-Lopez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - José Rodrigo-Rodríguez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Angel Merchan-Perez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Universidad Politécnica de Madrid, Madrid, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
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5
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Sierra C, Sabariego-Navarro M, Fernández-Blanco Á, Cruciani S, Zamora-Moratalla A, Novoa EM, Dierssen M. The lncRNA Snhg11, a new candidate contributing to neurogenesis, plasticity, and memory deficits in Down syndrome. Mol Psychiatry 2024:10.1038/s41380-024-02440-9. [PMID: 38409595 DOI: 10.1038/s41380-024-02440-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 02/28/2024]
Abstract
Down syndrome (DS) stands as the prevalent genetic cause of intellectual disability, yet comprehensive understanding of its cellular and molecular underpinnings remains limited. In this study, we explore the cellular landscape of the hippocampus in a DS mouse model, the Ts65Dn, through single-nuclei transcriptional profiling. Our findings demonstrate that trisomy manifests as a highly specific modification of the transcriptome within distinct cell types. Remarkably, we observed a significant shift in the transcriptomic profile of granule cells in the dentate gyrus (DG) associated with trisomy. We identified the downregulation of a specific small nucleolar RNA host gene, Snhg11, as the primary driver behind this observed shift in the trisomic DG. Notably, reduced levels of Snhg11 in this region were also observed in a distinct DS mouse model, the Dp(16)1Yey, as well as in human postmortem brain tissue, indicating its relevance in Down syndrome. To elucidate the function of this long non-coding RNA (lncRNA), we knocked down Snhg11 in the DG of wild-type mice. Intriguingly, this intervention alone was sufficient to impair synaptic plasticity and adult neurogenesis, resembling the cognitive phenotypes associated with trisomy in the hippocampus. Our study uncovers the functional role of Snhg11 in the DG and underscores the significance of this lncRNA in intellectual disability. Furthermore, our findings highlight the importance of DG in the memory deficits observed in Down syndrome.
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Affiliation(s)
- Cesar Sierra
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, 08003, Spain.
| | - Miguel Sabariego-Navarro
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, 08003, Spain
- Universitat Pompeu Fabra (UPF), Dr Aiguader 88, Barcelona, 08003, Spain
| | - Álvaro Fernández-Blanco
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, 08003, Spain
| | - Sonia Cruciani
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, 08003, Spain
- Universitat Pompeu Fabra (UPF), Dr Aiguader 88, Barcelona, 08003, Spain
| | - Alfonsa Zamora-Moratalla
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, 08003, Spain
| | - Eva Maria Novoa
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, 08003, Spain
- Universitat Pompeu Fabra (UPF), Dr Aiguader 88, Barcelona, 08003, Spain
| | - Mara Dierssen
- Universitat Pompeu Fabra (UPF), Dr Aiguader 88, Barcelona, 08003, Spain.
- Biomedical Research Networking Center for Rare Diseases (CIBERER), Barcelona, Spain.
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6
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Jiang SZ, Shahoha M, Zhang HY, Brancaleone W, Elkahloun A, Tejeda HA, Ashery U, Eiden LE. The guanine nucleotide exchange factor RapGEF2 is required for ERK-dependent immediate-early gene (Egr1) activation during fear memory formation. Cell Mol Life Sci 2024; 81:48. [PMID: 38236296 PMCID: PMC11071968 DOI: 10.1007/s00018-023-04999-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: 04/24/2023] [Revised: 09/16/2023] [Accepted: 10/04/2023] [Indexed: 01/19/2024]
Abstract
The MAP kinase ERK is important for neuronal plasticity underlying associative learning, yet specific molecular pathways for neuronal ERK activation are undetermined. RapGEF2 is a neuron-specific cAMP sensor that mediates ERK activation. We investigated whether it is required for cAMP-dependent ERK activation leading to other downstream neuronal signaling events occurring during associative learning, and if RapGEF2-dependent signaling impairments affect learned behavior. Camk2α-cre+/-::RapGEF2fl/fl mice with depletion of RapGEF2 in hippocampus and amygdala exhibit impairments in context- and cue-dependent fear conditioning linked to corresponding impairment in Egr1 induction in these two brain regions. Camk2α-cre+/-::RapGEF2fl/fl mice show decreased RapGEF2 expression in CA1 and dentate gyrus associated with abolition of pERK and Egr1, but not of c-Fos induction, following fear conditioning, impaired freezing to context after fear conditioning, and impaired cAMP-dependent long-term potentiation at perforant pathway and Schaffer collateral synapses in hippocampal slices ex vivo. RapGEF2 expression is largely eliminated in basolateral amygdala, also involved in fear memory, in Camk2α-cre+/-::RapGEF2fl/fl mice. Neither Egr1 nor c-fos induction in BLA after fear conditioning, nor cue-dependent fear learning, are affected by ablation of RapGEF2 in BLA. However, Egr1 induction (but not that of c-fos) in BLA is reduced after restraint stress-augmented fear conditioning, as is freezing to cue after restraint stress-augmented fear conditioning, in Camk2α-cre+/-::RapGEF2fl/fl mice. Cyclic AMP-dependent GEFs have been genetically associated as risk factors for schizophrenia, a disorder associated with cognitive deficits. Here we show a functional link between one of them, RapGEF2, and cognitive processes involved in associative learning in amygdala and hippocampus.
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Affiliation(s)
- Sunny Zhihong Jiang
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | - Meishar Shahoha
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, and Sagol School of Neuroscience, Tel Aviv University, Sherman Building Rm 719, Ramat Aviv, 69978, Tel Aviv, Israel
| | - Hai-Ying Zhang
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | - William Brancaleone
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | | | - Hugo A Tejeda
- Unit on Neuromodulation and Synaptic Integration, NIMH-IRP, Bethesda, MD, USA
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, and Sagol School of Neuroscience, Tel Aviv University, Sherman Building Rm 719, Ramat Aviv, 69978, Tel Aviv, Israel.
| | - Lee E Eiden
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA.
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Samavat M, Bartol TM, Bromer C, Hubbard DD, Hanka DC, Kuwajima M, Mendenhall JM, Parker PH, Bowden JB, Abraham WC, Sejnowski TJ, Harris KM. Long-Term Potentiation Produces a Sustained Expansion of Synaptic Information Storage Capacity in Adult Rat Hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.574766. [PMID: 38260636 PMCID: PMC10802612 DOI: 10.1101/2024.01.12.574766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Long-term potentiation (LTP) has become a standard model for investigating synaptic mechanisms of learning and memory. Increasingly, it is of interest to understand how LTP affects the synaptic information storage capacity of the targeted population of synapses. Here, structural synaptic plasticity during LTP was explored using three-dimensional reconstruction from serial section electron microscopy. Storage capacity was assessed by applying a new analytical approach, Shannon information theory, to delineate the number of functionally distinguishable synaptic strengths. LTP was induced by delta-burst stimulation of perforant pathway inputs to the middle molecular layer of hippocampal dentate granule cells in adult rats. Spine head volumes were measured as predictors of synaptic strength and compared between LTP and control hemispheres at 30 min and 2 hr after the induction of LTP. Synapses from the same axon onto the same dendrite were used to determine the precision of synaptic plasticity based on the similarity of their physical dimensions. Shannon entropy was measured by exploiting the frequency of spine heads in functionally distinguishable sizes to assess the degree to which LTP altered the number of bits of information storage. Outcomes from these analyses reveal that LTP expanded storage capacity; the distribution of spine head volumes was increased from 2 bits in controls to 3 bits at 30 min and 2.7 bits at 2 hr after the induction of LTP. Furthermore, the distribution of spine head volumes was more uniform across the increased number of functionally distinguishable sizes following LTP, thus achieving more efficient use of coding space across the population of synapses.
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Affiliation(s)
- Mohammad Samavat
- Department of Electrical and Computer Engineering, Jacobs School of Engineering, UC San Diego
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
| | - Thomas M Bartol
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
| | - Cailey Bromer
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
| | - Dusten D Hubbard
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Dakota C Hanka
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Masaaki Kuwajima
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - John M Mendenhall
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Patrick H Parker
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Jared B Bowden
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712
| | - Wickliffe C Abraham
- Department of Psychology and Brain Health Research Centre, University of Otago, Dunedin, 9016, New Zealand
| | - Terrence J Sejnowski
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Kristen M Harris
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712
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8
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Karbowski J, Urban P. Information encoded in volumes and areas of dendritic spines is nearly maximal across mammalian brains. Sci Rep 2023; 13:22207. [PMID: 38097675 PMCID: PMC10721930 DOI: 10.1038/s41598-023-49321-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 12/06/2023] [Indexed: 12/17/2023] Open
Abstract
Many experiments suggest that long-term information associated with neuronal memory resides collectively in dendritic spines. However, spines can have a limited size due to metabolic and neuroanatomical constraints, which should effectively limit the amount of encoded information in excitatory synapses. This study investigates how much information can be stored in the population of sizes of dendritic spines, and whether it is optimal in any sense. It is shown here, using empirical data for several mammalian brains across different regions and physiological conditions, that dendritic spines nearly maximize entropy contained in their volumes and surface areas for a given mean size in cortical and hippocampal regions. Although both short- and heavy-tailed fitting distributions approach [Formula: see text] of maximal entropy in the majority of cases, the best maximization is obtained primarily for short-tailed gamma distribution. We find that most empirical ratios of standard deviation to mean for spine volumes and areas are in the range [Formula: see text], which is close to the theoretical optimal ratios coming from entropy maximization for gamma and lognormal distributions. On average, the highest entropy is contained in spine length ([Formula: see text] bits per spine), and the lowest in spine volume and area ([Formula: see text] bits), although the latter two are closer to optimality. In contrast, we find that entropy density (entropy per spine size) is always suboptimal. Our results suggest that spine sizes are almost as random as possible given the constraint on their size, and moreover the general principle of entropy maximization is applicable and potentially useful to information and memory storing in the population of cortical and hippocampal excitatory synapses, and to predicting their morphological properties.
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Affiliation(s)
- Jan Karbowski
- Institute of Applied Mathematics and Mechanics, University of Warsaw, Warsaw, Poland.
| | - Paulina Urban
- Laboratory of Functional and Structural Genomics, Centre of New Technologies, University of Warsaw, Warsaw, Poland
- College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw, Poland
- Laboratory of Databases and Business Analytics, National Information Processing Institute, National Research Institute, Warsaw, Poland
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9
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Sierra C, Sabariego-Navarro M, Fernández-Blanco Á, Cruciani S, Zamora-Moratalla A, Novoa EM, Dierssen M. The lncRNA Snhg11, a new candidate contributing to neurogenesis, plasticity and memory deficits in Down syndrome. RESEARCH SQUARE 2023:rs.3.rs-3184329. [PMID: 37841843 PMCID: PMC10571621 DOI: 10.21203/rs.3.rs-3184329/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Down syndrome (DS) stands as the prevalent genetic cause of intellectual disability, yet comprehensive understanding of its cellular and molecular underpinnings remains limited. In this study, we explore the cellular landscape of the hippocampus in a DS mouse model through single-nuclei transcriptional profiling. Our findings demonstrate that trisomy manifests as a highly specific modification of the transcriptome within distinct cell types. Remarkably, we observed a significant shift in the transcriptomic profile of granule cells in the dentate gyrus (DG) associated with trisomy. We identified the downregulation of a specific small nucleolar RNA host gene, Snhg11, as the primary driver behind this observed shift in the trisomic DG. Notably, reduced levels of Snhg11 in this region were also observed in a distinct DS mouse model, the Dp(16)1Yey, as well as in human postmortem tissue, indicating its relevance in Down syndrome. To elucidate the function of this long non-coding RNA (lncRNA), we knocked down Snhg11 in the DG of wild-type mice. Intriguingly, this intervention alone was sufficient to impair synaptic plasticity and adult neurogenesis, resembling the cognitive phenotypes associated with trisomy in the hippocampus. Our study uncovers the functional role of Snhg11 in the DG and underscores the significance of this lncRNA in intellectual disability. Furthermore, our findings highlight the importance of the DG in the memory deficits observed in Down syndrome.
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Affiliation(s)
- Cesar Sierra
- Center for Genomic Regulation, The Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
| | - Miguel Sabariego-Navarro
- Center for Genomic Regulation, The Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
| | - Álvaro Fernández-Blanco
- Center for Genomic Regulation, The Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
| | - Sonia Cruciani
- Center for Genomic Regulation, The Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
| | - Alfonsa Zamora-Moratalla
- Center for Genomic Regulation, The Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
| | - Eva Maria Novoa
- Center for Genomic Regulation, The Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
- Department of Experimental and Health Sciences, University Pompeu Fabra, 08003 Barcelona, Spain
| | - Mara Dierssen
- Center for Genomic Regulation, The Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
- Department of Experimental and Health Sciences, University Pompeu Fabra, 08003 Barcelona, Spain
- Biomedical Research Networking Center for Rare Diseases (CIBERER), 08003 Barcelona, Spain
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10
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Südhof TC. Cerebellin-neurexin complexes instructing synapse properties. Curr Opin Neurobiol 2023; 81:102727. [PMID: 37209532 DOI: 10.1016/j.conb.2023.102727] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/22/2023]
Abstract
Cerebellins (Cbln1-4) are secreted adaptor proteins that connect presynaptic neurexins (Nrxn1-3) to postsynaptic ligands (GluD1/2 for Cbln1-3 vs. DCC and Neogenin-1 for Cbln4). Classical studies demonstrated that neurexin-Cbln1-GluD2 complexes organize cerebellar parallel-fiber synapses, but the role of cerebellins outside of the cerebellum has only recently been clarified. In synapses of the hippocampal subiculum and prefrontal cortex, Nrxn1-Cbln2-GluD1 complexes strikingly upregulate postsynaptic NMDA-receptors, whereas Nrxn3-Cbln2-GluD1 complexes conversely downregulate postsynaptic AMPA-receptors. At perforant-path synapses in the dentate gyrus, in contrast, neurexin/Cbln4/Neogenin-1 complexes are essential for LTP without affecting basal synaptic transmission or NMDA- or AMPA-receptors. None of these signaling pathways are required for synapse formation. Thus, outside of the cerebellum neurexin/cerebellin complexes regulate synapse properties by activating specific downstream receptors.
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Affiliation(s)
- Thomas C Südhof
- Dept. of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford CA 94305, USA.
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11
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Schmitt O, Eipert P, Wang Y, Kanoke A, Rabiller G, Liu J. Connectome-based prediction of functional impairment in experimental stroke models. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.05.539601. [PMID: 37205373 PMCID: PMC10187266 DOI: 10.1101/2023.05.05.539601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Experimental rat models of stroke and hemorrhage are important tools to investigate cerebrovascular disease pathophysiology mechanisms, yet how significant patterns of functional impairment induced in various models of stroke are related to changes in connectivity at the level of neuronal populations and mesoscopic parcellations of rat brains remain unresolved. To address this gap in knowledge, we employed two middle cerebral artery occlusion models and one intracerebral hemorrhage model with variant extent and location of neuronal dysfunction. Motor and spatial memory function was assessed and the level of hippocampal activation via Fos immunohistochemistry. Contribution of connectivity change to functional impairment was analyzed for connection similarities, graph distances and spatial distances as well as the importance of regions in terms of network architecture based on the neuroVIISAS rat connectome. We found that functional impairment correlated with not only the extent but also the locations of the injury among the models. In addition, via coactivation analysis in dynamic rat brain models, we found that lesioned regions led to stronger coactivations with motor function and spatial learning regions than with other unaffected regions of the connectome. Dynamic modeling with the weighted bilateral connectome detected changes in signal propagation in the remote hippocampus in all 3 stroke types, predicting the extent of hippocampal hypoactivation and impairment in spatial learning and memory function. Our study provides a comprehensive analytical framework in predictive identification of remote regions not directly altered by stroke events and their functional implication.
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Affiliation(s)
- Oliver Schmitt
- Medical School Hamburg - University of Applied Sciences, Department of Anatomy; University of Rostock, Institute of Anatomy
- SFVAMC, 1700 Owens Street, San Francisco, CA 94158
| | - Peter Eipert
- Medical School Hamburg - University of Applied Sciences, Department of Anatomy; University of Rostock, Institute of Anatomy
- SFVAMC, 1700 Owens Street, San Francisco, CA 94158
| | - Yonggang Wang
- Department of Neurological Surgery, UCSF
- SFVAMC, 1700 Owens Street, San Francisco, CA 94158
- Department of Neurological Surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, PR China, 100050
| | - Atsushi Kanoke
- Department of Neurological Surgery, UCSF
- SFVAMC, 1700 Owens Street, San Francisco, CA 94158
- Department of Neurosurgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Gratianne Rabiller
- Department of Neurological Surgery, UCSF
- SFVAMC, 1700 Owens Street, San Francisco, CA 94158
| | - Jialing Liu
- Department of Neurological Surgery, UCSF
- SFVAMC, 1700 Owens Street, San Francisco, CA 94158
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12
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Heidarli E, Vatanpour H, Nasri Nasrabadi N, Soltani M, Tahmasebi S, Faizi M. The Effects of the Fraction Isolated from Iranian Buthotus shach Scorpion Venom on Synaptic Plasticity, Learning, Memory, and Seizure Susceptibility. IRANIAN JOURNAL OF PHARMACEUTICAL RESEARCH : IJPR 2023; 22:e138273. [PMID: 38444716 PMCID: PMC10912865 DOI: 10.5812/ijpr-138273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/14/2023] [Accepted: 09/03/2023] [Indexed: 03/07/2024]
Abstract
Epilepsy, as a neurological disease, can be defined as frequent seizure attacks. Further, it affects many other aspects of patients' mental activities, such as learning and memory. Scorpion venoms have gained notice as compounds with potential antiepileptic properties. Among them, Buthotus schach (BS) is one of the Iranian scorpions studied by Aboutorabi et al., who fractionated, characterized, and tested this compound using electrophysiological techniques in brain slices (patch-clamp recording). In the present study, the fraction obtained from gel electrophoresis was investigated through behavioral and electrophysiological assays. At first, ventricular cannulation was performed in rats, and then the active fraction (i.e., F3), carbamazepine, and the vehicle were microinjected into the brain before seizure induction by the subcutaneous (SC) injection of pentylenetetrazol (PTZ). Seizure behaviors were scaled according to Racine stages. Memory and learning were evaluated using the Y-maze and passive avoidance tests. Other groups entered evoked field potential recording after microinjection and seizure induction. Population spike (PS) and field excitatory postsynaptic potential (fEPSP) were measured. The F3 fraction could prevent the fifth stage and postpone the third stage of seizure compared to the control (carbamazepine) group. There was no significant improvement in memory and learning in the group treated with the F3 fraction. Also, PS amplitude and fEPSP slope increased significantly, and long-term potentiation was successfully formed after the high-frequency stimulation of the performant pathway. Our results support the antiepileptic effects of the F3 fraction of BS venom, evidenced by behavioral and electrophysiological studies. However, the effects of this fraction on memory and learning were not in the same direction, suggesting the involvement of two different pathways.
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Affiliation(s)
- Elmira Heidarli
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Vatanpour
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Nafiseh Nasri Nasrabadi
- Pharmaceutical Sciences Research Centre, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maha Soltani
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Saeed Tahmasebi
- Department of Cognitive Science, Science and Research Branch, Islamic Azad University Tehran, Tehran, Iran
| | - Mehrdad Faizi
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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13
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Dorkenwald S, Turner NL, Macrina T, Lee K, Lu R, Wu J, Bodor AL, Bleckert AA, Brittain D, Kemnitz N, Silversmith WM, Ih D, Zung J, Zlateski A, Tartavull I, Yu SC, Popovych S, Wong W, Castro M, Jordan CS, Wilson AM, Froudarakis E, Buchanan J, Takeno MM, Torres R, Mahalingam G, Collman F, Schneider-Mizell CM, Bumbarger DJ, Li Y, Becker L, Suckow S, Reimer J, Tolias AS, Macarico da Costa N, Reid RC, Seung HS. Binary and analog variation of synapses between cortical pyramidal neurons. eLife 2022; 11:e76120. [PMID: 36382887 PMCID: PMC9704804 DOI: 10.7554/elife.76120] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 11/15/2022] [Indexed: 11/17/2022] Open
Abstract
Learning from experience depends at least in part on changes in neuronal connections. We present the largest map of connectivity to date between cortical neurons of a defined type (layer 2/3 [L2/3] pyramidal cells in mouse primary visual cortex), which was enabled by automated analysis of serial section electron microscopy images with improved handling of image defects (250 × 140 × 90 μm3 volume). We used the map to identify constraints on the learning algorithms employed by the cortex. Previous cortical studies modeled a continuum of synapse sizes by a log-normal distribution. A continuum is consistent with most neural network models of learning, in which synaptic strength is a continuously graded analog variable. Here, we show that synapse size, when restricted to synapses between L2/3 pyramidal cells, is well modeled by the sum of a binary variable and an analog variable drawn from a log-normal distribution. Two synapses sharing the same presynaptic and postsynaptic cells are known to be correlated in size. We show that the binary variables of the two synapses are highly correlated, while the analog variables are not. Binary variation could be the outcome of a Hebbian or other synaptic plasticity rule depending on activity signals that are relatively uniform across neuronal arbors, while analog variation may be dominated by other influences such as spontaneous dynamical fluctuations. We discuss the implications for the longstanding hypothesis that activity-dependent plasticity switches synapses between bistable states.
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Affiliation(s)
- Sven Dorkenwald
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - Nicholas L Turner
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - Thomas Macrina
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - Kisuk Lee
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Brain & Cognitive Sciences Department, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Ran Lu
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Jingpeng Wu
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Agnes L Bodor
- Allen Institute for Brain ScienceSeattleUnited States
| | | | | | - Nico Kemnitz
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | | | - Dodam Ih
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Jonathan Zung
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Aleksandar Zlateski
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Ignacio Tartavull
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Szi-Chieh Yu
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Sergiy Popovych
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - William Wong
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Manuel Castro
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Chris S Jordan
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Alyssa M Wilson
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Emmanouil Froudarakis
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Center for Neuroscience and Artificial Intelligence, Baylor College of MedicineHoustonUnited States
| | | | - Marc M Takeno
- Allen Institute for Brain ScienceSeattleUnited States
| | - Russel Torres
- Allen Institute for Brain ScienceSeattleUnited States
| | | | | | | | | | - Yang Li
- Allen Institute for Brain ScienceSeattleUnited States
| | - Lynne Becker
- Allen Institute for Brain ScienceSeattleUnited States
| | - Shelby Suckow
- Allen Institute for Brain ScienceSeattleUnited States
| | - Jacob Reimer
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Center for Neuroscience and Artificial Intelligence, Baylor College of MedicineHoustonUnited States
| | - Andreas S Tolias
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Center for Neuroscience and Artificial Intelligence, Baylor College of MedicineHoustonUnited States
- Department of Electrical and Computer Engineering, Rice UniversityHoustonUnited States
| | | | - R Clay Reid
- Allen Institute for Brain ScienceSeattleUnited States
| | - H Sebastian Seung
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
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14
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Martinez-Saito M. Discrete scaling and criticality in a chain of adaptive excitable integrators. CHAOS, SOLITONS & FRACTALS 2022; 163:112574. [DOI: 10.1016/j.chaos.2022.112574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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15
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Imoto Y, Raychaudhuri S, Ma Y, Fenske P, Sandoval E, Itoh K, Blumrich EM, Matsubayashi HT, Mamer L, Zarebidaki F, Söhl-Kielczynski B, Trimbuch T, Nayak S, Iwasa JH, Liu J, Wu B, Ha T, Inoue T, Jorgensen EM, Cousin MA, Rosenmund C, Watanabe S. Dynamin is primed at endocytic sites for ultrafast endocytosis. Neuron 2022; 110:2815-2835.e13. [PMID: 35809574 PMCID: PMC9464723 DOI: 10.1016/j.neuron.2022.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 03/24/2022] [Accepted: 06/09/2022] [Indexed: 02/06/2023]
Abstract
Dynamin mediates fission of vesicles from the plasma membrane during endocytosis. Typically, dynamin is recruited from the cytosol to endocytic sites, requiring seconds to tens of seconds. However, ultrafast endocytosis in neurons internalizes vesicles as quickly as 50 ms during synaptic vesicle recycling. Here, we demonstrate that Dynamin 1 is pre-recruited to endocytic sites for ultrafast endocytosis. Specifically, Dynamin 1xA, a splice variant of Dynamin 1, interacts with Syndapin 1 to form molecular condensates on the plasma membrane. Single-particle tracking of Dynamin 1xA molecules confirms the liquid-like property of condensates in vivo. When Dynamin 1xA is mutated to disrupt its interaction with Syndapin 1, the condensates do not form, and consequently, ultrafast endocytosis slows down by 100-fold. Mechanistically, Syndapin 1 acts as an adaptor by binding the plasma membrane and stores Dynamin 1xA at endocytic sites. This cache bypasses the recruitment step and accelerates endocytosis at synapses.
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Affiliation(s)
- Yuuta Imoto
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA.
| | - Sumana Raychaudhuri
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Ye Ma
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Pascal Fenske
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Eduardo Sandoval
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kie Itoh
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Eva-Maria Blumrich
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; The Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; Simons Initiatives for the Developing Brain, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK
| | - Hideaki T Matsubayashi
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Lauren Mamer
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Fereshteh Zarebidaki
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | | | - Thorsten Trimbuch
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Shraddha Nayak
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Janet H Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Jian Liu
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK
| | - Bin Wu
- The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Baltimore, MD 21205, USA
| | - Takanari Inoue
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Erik M Jorgensen
- HHMI, Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; The Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; Simons Initiatives for the Developing Brain, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK
| | - Christian Rosenmund
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany.
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA.
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16
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Harris KM, Hubbard DD, Kuwajima M, Abraham WC, Bourne JN, Bowden JB, Haessly A, Mendenhall JM, Parker PH, Shi B, Spacek J. Dendritic Spine Density Scales with Microtubule Number in Rat Hippocampal Dendrites. Neuroscience 2022; 489:84-97. [PMID: 35218884 PMCID: PMC9038701 DOI: 10.1016/j.neuroscience.2022.02.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 12/14/2022]
Abstract
Microtubules deliver essential resources to and from synapses. Three-dimensional reconstructions in rat hippocampus reveal a sampling bias regarding spine density that needs to be controlled for dendrite caliber and resource delivery based on microtubule number. The strength of this relationship varies across dendritic arbors, as illustrated for area CA1 and dentate gyrus. In both regions, proximal dendrites had more microtubules than distal dendrites. For CA1 pyramidal cells, spine density was greater on thicker than thinner dendrites in stratum radiatum, or on the more uniformly thin terminal dendrites in stratum lacunosum moleculare. In contrast, spine density was constant across the cone shaped arbor of tapering dendrites from dentate granule cells. These differences suggest that thicker dendrites supply microtubules to subsequent dendritic branches and local dendritic spines, whereas microtubules in thinner dendrites need only provide resources to local spines. Most microtubules ran parallel to dendrite length and associated with long, presumably stable mitochondria, which occasionally branched into lateral dendritic branches. Short, presumably mobile, mitochondria were tethered to microtubules that bent and appeared to direct them into a thin lateral branch. Prior work showed that dendritic segments with the same number of microtubules had elevated resources in subregions of their dendritic shafts where spine synapses had enlarged, and spine clusters had formed. Thus, additional microtubules were not required for redistribution of resources locally to growing spines or synapses. These results provide new understanding about the potential for microtubules to regulate resource delivery to and from dendritic branches and locally among dendritic spines.
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Affiliation(s)
- Kristen M Harris
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States.
| | - Dusten D Hubbard
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Masaaki Kuwajima
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Wickliffe C Abraham
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Jennifer N Bourne
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Jared B Bowden
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Andrea Haessly
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - John M Mendenhall
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Patrick H Parker
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Bitao Shi
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Josef Spacek
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
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17
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Chipman PH, Fung CCA, Pazo Fernandez A, Sawant A, Tedoldi A, Kawai A, Ghimire Gautam S, Kurosawa M, Abe M, Sakimura K, Fukai T, Goda Y. Astrocyte GluN2C NMDA receptors control basal synaptic strengths of hippocampal CA1 pyramidal neurons in the stratum radiatum. eLife 2021; 10:70818. [PMID: 34693906 PMCID: PMC8594917 DOI: 10.7554/elife.70818] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 10/22/2021] [Indexed: 12/12/2022] Open
Abstract
Experience-dependent plasticity is a key feature of brain synapses for which neuronal N-Methyl-D-Aspartate receptors (NMDARs) play a major role, from developmental circuit refinement to learning and memory. Astrocytes also express NMDARs, although their exact function has remained controversial. Here, we identify in mouse hippocampus, a circuit function for GluN2C NMDAR, a subtype highly expressed in astrocytes, in layer-specific tuning of synaptic strengths in CA1 pyramidal neurons. Interfering with astrocyte NMDAR or GluN2C NMDAR activity reduces the range of presynaptic strength distribution specifically in the stratum radiatum inputs without an appreciable change in the mean presynaptic strength. Mathematical modeling shows that narrowing of the width of presynaptic release probability distribution compromises the expression of long-term synaptic plasticity. Our findings suggest a novel feedback signaling system that uses astrocyte GluN2C NMDARs to adjust basal synaptic weight distribution of Schaffer collateral inputs, which in turn impacts computations performed by the CA1 pyramidal neuron.
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Affiliation(s)
| | - Chi Chung Alan Fung
- Neural Coding and Brain Computing Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | | | | | - Angelo Tedoldi
- RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
| | - Atsushi Kawai
- RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
| | | | | | - Manabu Abe
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata, Japan
| | - Kenji Sakimura
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata, Japan
| | - Tomoki Fukai
- Neural Coding and Brain Computing Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Yukiko Goda
- RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
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18
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Smilovic D, Rietsche M, Drakew A, Vuksic M, Deller T. Constitutive tumor necrosis factor (TNF)-deficiency causes a reduction in spine density in mouse dentate granule cells accompanied by homeostatic adaptations of spine head size. J Comp Neurol 2021; 530:656-669. [PMID: 34498735 DOI: 10.1002/cne.25237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 07/16/2021] [Accepted: 08/15/2021] [Indexed: 01/14/2023]
Abstract
The majority of excitatory synapses terminating on cortical neurons are found on dendritic spines. The geometry of spines, in particular the size of the spine head, tightly correlates with the strength of the excitatory synapse formed with the spine. Under conditions of synaptic plasticity, spine geometry may change, reflecting functional adaptations. Since the cytokine tumor necrosis factor (TNF) has been shown to influence synaptic transmission as well as Hebbian and homeostatic forms of synaptic plasticity, we speculated that TNF-deficiency may cause concomitant structural changes at the level of dendritic spines. To address this question, we analyzed spine density and spine head area of Alexa568-filled granule cells in the dentate gyrus of adult C57BL/6J and TNF-deficient (TNF-KO) mice. Tissue sections were double-stained for the actin-modulating and plasticity-related protein synaptopodin (SP), a molecular marker for strong and stable spines. Dendritic segments of TNF-deficient granule cells exhibited ∼20% fewer spines in the outer molecular layer of the dentate gyrus compared to controls, indicating a reduced afferent innervation. Of note, these segments also had larger spines containing larger SP-clusters. This pattern of changes is strikingly similar to the one seen after denervation-associated spine loss following experimental entorhinal denervation of granule cells: Denervated granule cells increase the SP-content and strength of their remaining spines to homeostatically compensate for those that were lost. Our data suggest a similar compensatory mechanism in TNF-deficient granule cells in response to a reduction in their afferent innervation.
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Affiliation(s)
- Dinko Smilovic
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt/Main, Germany.,Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Michael Rietsche
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt/Main, Germany
| | - Alexander Drakew
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt/Main, Germany
| | - Mario Vuksic
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt/Main, Germany.,Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt/Main, Germany
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19
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Seo S, Sizemore RJ, Reader KL, Smither RA, Wicky HE, Hughes SM, Bilkey DK, Parr-Brownlie LC, Oorschot DE. A schizophrenia risk factor induces marked anatomical deficits at GABAergic-dopaminergic synapses in the rat ventral tegmental area: Essential evidence for new targeted therapies. J Comp Neurol 2021; 529:3946-3973. [PMID: 34338311 DOI: 10.1002/cne.25225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/07/2021] [Accepted: 07/26/2021] [Indexed: 11/09/2022]
Abstract
To develop new therapies for schizophrenia, evidence accumulated over decades highlights the essential need to investigate the GABAergic synapses that presynaptically influence midbrain dopaminergic neurons. Since current technology restricts these studies to animals, and evidence accumulated in recent decades indicates a developmental origin of schizophrenia, we investigated synaptic changes in male rat offspring exposed to maternal immune activation (MIA), a schizophrenia risk factor. Using a novel combination of lentiviruses, peroxidase-immunogold double labeling, three-dimensional serial section transmission electron microscopy and stereology, we observed clear anatomical alterations in synaptic inputs on dopaminergic neurons in the midbrain posterior ventral tegmental area (pVTA). These changes relate directly to a characteristic feature of schizophrenia: increased dopamine release. In 3-month-old and 14-month-old MIA rats, we found a marked decrease in the volume of presynaptic GABAergic terminals from the rostromedial tegmental nucleus (RMTg) and in the length of the synapses they made, when innervating pVTA dopaminergic neurons. In MIA rats in the long-term, we also discovered a decrease in the volume of the postsynaptic density (PSD) and in the maximum thickness of the PSD at the same synapses. These marked deficits were evident in conventional GABA-dopamine synapses and in synaptic triads that we discovered involving asymmetric synapses that innervated RMTg GABAergic presynaptic terminals, which in turn innervated pVTA dopaminergic neurons. In triads, the PSD thickness of asymmetric synapses was significantly decreased in MIA rats in the long-term cohort. The extensive anatomical deficits provide a potential basis for new therapies targeted at synaptic inputs on midbrain pVTA dopaminergic neurons, in contrast to current striatum-targeted antipsychotic drugs.
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Affiliation(s)
- Steve Seo
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Rachel J Sizemore
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Karen L Reader
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Roseanna A Smither
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand
| | - Hollie E Wicky
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand.,Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Stephanie M Hughes
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand.,Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - David K Bilkey
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Louise C Parr-Brownlie
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand
| | - Dorothy E Oorschot
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
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20
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Goetz L, Roth A, Häusser M. Active dendrites enable strong but sparse inputs to determine orientation selectivity. Proc Natl Acad Sci U S A 2021; 118:e2017339118. [PMID: 34301882 PMCID: PMC8325157 DOI: 10.1073/pnas.2017339118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The dendrites of neocortical pyramidal neurons are excitable. However, it is unknown how synaptic inputs engage nonlinear dendritic mechanisms during sensory processing in vivo, and how they in turn influence action potential output. Here, we provide a quantitative account of the relationship between synaptic inputs, nonlinear dendritic events, and action potential output. We developed a detailed pyramidal neuron model constrained by in vivo dendritic recordings. We drive this model with realistic input patterns constrained by sensory responses measured in vivo and connectivity measured in vitro. We show mechanistically that under realistic conditions, dendritic Na+ and NMDA spikes are the major determinants of neuronal output in vivo. We demonstrate that these dendritic spikes can be triggered by a surprisingly small number of strong synaptic inputs, in some cases even by single synapses. We predict that dendritic excitability allows the 1% strongest synaptic inputs of a neuron to control the tuning of its output. Active dendrites therefore allow smaller subcircuits consisting of only a few strongly connected neurons to achieve selectivity for specific sensory features.
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Affiliation(s)
- Lea Goetz
- Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, United Kingdom
| | - Arnd Roth
- Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, United Kingdom
| | - Michael Häusser
- Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, United Kingdom
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21
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Collitti-Klausnitzer J, Hagena H, Dubovyk V, Manahan-Vaughan D. Preferential frequency-dependent induction of synaptic depression by the lateral perforant path and of synaptic potentiation by the medial perforant path inputs to the dentate gyrus. Hippocampus 2021; 31:957-981. [PMID: 34002905 DOI: 10.1002/hipo.23338] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 04/28/2021] [Accepted: 05/02/2021] [Indexed: 12/19/2022]
Abstract
The encoding of spatial representations is enabled by synaptic plasticity. The entorhinal cortex sends information to the hippocampus via the lateral (LPP) and medial perforant (MPP) paths that transfer egocentric item-related and allocentric spatial information, respectively. To what extent LPP and MPP information-relay results in different homosynaptic synaptic plasticity responses is unclear. We examined the frequency dependency (at 1, 5, 10, 50, 100, 200 Hz) of long-term potentiation (LTP) and long-term depression (LTD) at MPP and LPP synapses in the dentate gyrus (DG) of freely behaving adult rats. We report that whereas the MPP-DG synapses exhibit a predisposition toward the expression of LTP, LPP-DG synapses prefer to express synaptic depression. The divergence of synaptic plasticity responses is most prominent at afferent frequencies of 5, 100, Hz and 200 Hz. Priming with 10 or 50 Hz significantly modified the subsequent plasticity response in a frequency-dependent manner, but failed to change the preferred direction of change in synaptic strength of MPP and LPP synapses. Evaluation of the expression of GluN1, GluN2A, or GluN2B subunits of the NMDA receptor revealed equivalent expression in the outer and middle thirds of the molecular layer where LPP and MPP inputs convene, respectively, thus excluding NMDA receptors as a substrate for the frequency-dependent differences in bidirectional plasticity. These findings demonstrate that the LPP and MPP inputs to the DG enable differentiated and distinct forms of synaptic plasticity in response to the same afferent frequencies. Effects are extremely robust and resilient to metaplastic priming. These properties may support the functional differentiation of allocentric and item information provided to the DG by the MPP and LPP, respectively, that has been proposed by others. We propose that allocentric spatial information, conveyed by the MPP is encoded through hippocampal LTP in a designated synaptic network. This network is refined and optimized to include egocentric contextual information through LTD triggered by LPP inputs.
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Affiliation(s)
| | - Hardy Hagena
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Germany
| | - Valentyna Dubovyk
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Germany
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22
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Hoang TH, Böge J, Manahan-Vaughan D. Hippocampal subfield-specific Homer1a expression is triggered by learning-facilitated long-term potentiation and long-term depression at medial perforant path synapses. Hippocampus 2021; 31:897-915. [PMID: 33964041 DOI: 10.1002/hipo.23333] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 03/22/2021] [Accepted: 04/11/2021] [Indexed: 12/23/2022]
Abstract
Learning about general aspects, or content details, of space results in differentiated neuronal information encoding within the proximodistal axis of the hippocampus. These processes are tightly linked to long-term potentiation (LTP) and long-term depression (LTD). Here, we explored the precise sites of encoding of synaptic plasticity in the hippocampus that are mediated by information throughput from the perforant path. We assessed nuclear Homer1a-expression that was triggered by electrophysiological induction of short and long forms of hippocampal synaptic plasticity, and compared it to Homer1a-expression that was triggered by LTP and LTD enabled by different forms of spatial learning. Plasticity responses were induced by patterned stimulation of the perforant path and were recorded in the dentate gyrus (DG) of freely behaving rats. We used fluorescence in situ hybridization to detect experience-dependent nuclear encoding of Homer1a in proximodistal hippocampal subfields. Induction of neither STP nor STD resulted in immediate early gene (IEG) encoding. Electrophysiological induction of robust LTP, or LTD, resulted in highly significant and widespread induction of nuclear Homer1a in all hippocampal subfields. LTP that was facilitated by novel spatial exploration triggered similar widespread Homer1a-expression. The coupling of synaptic depression with the exploration of a novel configuration of landmarks resulted in localized IEG expression in the proximal CA3 region and the lower (infrapyramidal) blade of the DG. Our findings support that synaptic plasticity induction via perforant path inputs promotes widespread hippocampal information encoding. Furthermore, novel spatial exploration promotes the selection of a hippocampal neuronal network by means of LTP that is distributed in an experience-dependent manner across all hippocampus subfields. This network may be modified during spatial content learning by LTD in specific hippocampal subfields. Thus, long-term plasticity-inducing events result in IEG expression that supports establishment and/or restructuring of neuronal networks that are necessary for long-term information storage.
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Affiliation(s)
- Thu-Huong Hoang
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr University Bochum, Bochum, Germany
| | - Juliane Böge
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum, Bochum, Germany
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23
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Zhu Y, Uytiepo M, Bushong E, Haberl M, Beutter E, Scheiwe F, Zhang W, Chang L, Luu D, Chui B, Ellisman M, Maximov A. Nanoscale 3D EM reconstructions reveal intrinsic mechanisms of structural diversity of chemical synapses. Cell Rep 2021; 35:108953. [PMID: 33826888 PMCID: PMC8354523 DOI: 10.1016/j.celrep.2021.108953] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/21/2021] [Accepted: 03/15/2021] [Indexed: 10/25/2022] Open
Abstract
Chemical synapses of shared cellular origins have remarkably heterogeneous structures, but how this diversity is generated is unclear. Here, we use three-dimensional (3D) electron microscopy and artificial intelligence algorithms for image processing to reconstruct functional excitatory microcircuits in the mouse hippocampus and microcircuits in which neurotransmitter signaling is permanently suppressed with genetic tools throughout the lifespan. These nanoscale analyses reveal that experience is dispensable for morphogenesis of synapses with different geometric shapes and contents of membrane organelles and that arrangement of morphologically distinct connections in local networks is stochastic. Moreover, loss of activity increases the variability in sizes of opposed pre- and postsynaptic structures without disrupting their alignments, suggesting that inherently variable weights of naive connections become progressively matched with repetitive use. These results demonstrate that mechanisms for the structural diversity of neuronal synapses are intrinsic and provide insights into how circuits essential for memory storage assemble and integrate information.
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Affiliation(s)
- Yongchuan Zhu
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Marco Uytiepo
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Eric Bushong
- National Center for Microscopy and Imaging Research, University of California, San Diego, CA 92037, USA; Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, CA 92037, USA
| | - Matthias Haberl
- National Center for Microscopy and Imaging Research, University of California, San Diego, CA 92037, USA; Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, CA 92037, USA
| | - Elizabeth Beutter
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Frederieke Scheiwe
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Weiheng Zhang
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Lyanne Chang
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Danielle Luu
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Brandon Chui
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Mark Ellisman
- National Center for Microscopy and Imaging Research, University of California, San Diego, CA 92037, USA; Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, CA 92037, USA.
| | - Anton Maximov
- Department of Neuroscience, The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA.
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24
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Blazquez-Llorca L, Miguéns M, Montero-Crespo M, Selvas A, Gonzalez-Soriano J, Ambrosio E, DeFelipe J. 3D Synaptic Organization of the Rat CA1 and Alterations Induced by Cocaine Self-Administration. Cereb Cortex 2021; 31:1927-1952. [PMID: 33253368 PMCID: PMC7945021 DOI: 10.1093/cercor/bhaa331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 09/10/2020] [Accepted: 10/12/2020] [Indexed: 12/24/2022] Open
Abstract
The hippocampus plays a key role in contextual conditioning and has been proposed as an important component of the cocaine addiction brain circuit. To gain knowledge about cocaine-induced alterations in this circuit, we used focused ion beam milling/scanning electron microscopy to reveal and quantify the three-dimensional synaptic organization of the neuropil of the stratum radiatum of the rat CA1, under normal circumstances and after cocaine-self administration (SA). Most synapses are asymmetric (excitatory), macular-shaped, and in contact with dendritic spine heads. After cocaine-SA, the size and the complexity of the shape of both asymmetric and symmetric (inhibitory) synapses increased but no changes were observed in the synaptic density. This work constitutes the first detailed report on the 3D synaptic organization in the stratum radiatum of the CA1 field of cocaine-SA rats. Our data contribute to the elucidation of the normal and altered synaptic organization of the hippocampus, which is crucial for better understanding the neurobiological mechanisms underlying cocaine addiction.
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Affiliation(s)
- L Blazquez-Llorca
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid, Spain.,Sección Departamental de Anatomía y Embriología (Veterinaria), Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - M Miguéns
- Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain
| | - M Montero-Crespo
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
| | - A Selvas
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain
| | - J Gonzalez-Soriano
- Sección Departamental de Anatomía y Embriología (Veterinaria), Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - E Ambrosio
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain
| | - J DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
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25
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Zhang H, Bramham CR. Arc/Arg3.1 function in long-term synaptic plasticity: Emerging mechanisms and unresolved issues. Eur J Neurosci 2020; 54:6696-6712. [PMID: 32888346 DOI: 10.1111/ejn.14958] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 07/18/2020] [Accepted: 08/14/2020] [Indexed: 02/06/2023]
Abstract
Arc (activity-regulated cytoskeleton-associated protein) is posited as a critical regulator of long-term synaptic plasticity at excitatory synapses, including long-term potentiation, long-term depression, inverse synaptic tagging and homoeostatic scaling, with pivotal roles in memory and postnatal cortical development. However, the mechanisms underlying the bidirectional regulation of synaptic strength are poorly understood. Here we review evidence from different plasticity paradigms, highlight outstanding issues and discuss stimulus-specific mechanisms that dictate Arc function. We propose a model in which Arc bidirectionally controls synaptic strength by coordinate regulation of AMPA-type glutamate receptor (AMPAR) trafficking and actin cytoskeletal dynamics in dendritic spines. Key to this model, Arc is proposed to function as an activity-dependent regulator of AMPAR lateral membrane diffusion and trapping at synapses.
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Affiliation(s)
- Hongyu Zhang
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Clive R Bramham
- Department of Biomedicine, University of Bergen, Bergen, Norway
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26
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Montero-Crespo M, Dominguez-Alvaro M, Rondon-Carrillo P, Alonso-Nanclares L, DeFelipe J, Blazquez-Llorca L. Three-dimensional synaptic organization of the human hippocampal CA1 field. eLife 2020; 9:e57013. [PMID: 32690133 PMCID: PMC7375818 DOI: 10.7554/elife.57013] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 06/10/2020] [Indexed: 12/14/2022] Open
Abstract
The hippocampal CA1 field integrates a wide variety of subcortical and cortical inputs, but its synaptic organization in humans is still unknown due to the difficulties involved studying the human brain via electron microscope techniques. However, we have shown that the 3D reconstruction method using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) can be applied to study in detail the synaptic organization of the human brain obtained from autopsies, yielding excellent results. Using this technology, 24,752 synapses were fully reconstructed in CA1, revealing that most of them were excitatory, targeting dendritic spines and displaying a macular shape, regardless of the layer examined. However, remarkable differences were observed between layers. These data constitute the first extensive description of the synaptic organization of the neuropil of the human CA1 region.
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Affiliation(s)
- Marta Montero-Crespo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)MadridSpain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
| | - Marta Dominguez-Alvaro
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
| | - Patricia Rondon-Carrillo
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
| | - Lidia Alonso-Nanclares
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)MadridSpain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIIIMadridSpain
| | - Javier DeFelipe
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)MadridSpain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIIIMadridSpain
| | - Lidia Blazquez-Llorca
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED)MadridSpain
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27
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Harris KM. Structural LTP: from synaptogenesis to regulated synapse enlargement and clustering. Curr Opin Neurobiol 2020; 63:189-197. [PMID: 32659458 DOI: 10.1016/j.conb.2020.04.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/30/2020] [Indexed: 02/09/2023]
Abstract
Nature teaches us that form precedes function, yet structure and function are intertwined. Such is the case with synapse structure, function, and plasticity underlying learning, especially in the hippocampus, a crucial brain region for memory formation. As the hippocampus matures, enduring changes in synapse structure produced by long-term potentiation (LTP) shift from synaptogenesis to synapse enlargement that is homeostatically balanced by stalled spine outgrowth and local spine clustering. Production of LTP leads to silent spine outgrowth at P15, and silent synapse enlargement in adult hippocampus at 2hours, but not at 5 or 30min following induction. Here we consider structural LTP in the context of developmental stage and variation in the availability of local resources of endosomes, smooth endoplasmic reticulum and polyribosomes. The emerging evidence supports a need for more nuanced analysis of synaptic plasticity in the context of subcellular resource availability and developmental stage.
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28
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Lee CT, Laughlin JG, Moody JB, Amaro RE, McCammon JA, Holst M, Rangamani P. An Open-Source Mesh Generation Platform for Biophysical Modeling Using Realistic Cellular Geometries. Biophys J 2020; 118:1003-1008. [PMID: 32032503 PMCID: PMC7063475 DOI: 10.1016/j.bpj.2019.11.3400] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/08/2019] [Accepted: 11/27/2019] [Indexed: 11/16/2022] Open
Abstract
Advances in imaging methods such as electron microscopy, tomography, and other modalities are enabling high-resolution reconstructions of cellular and organelle geometries. Such advances pave the way for using these geometries for biophysical and mathematical modeling once these data can be represented as a geometric mesh, which, when carefully conditioned, enables the discretization and solution of partial differential equations. In this work, we outline the steps for a naïve user to approach the Geometry-preserving Adaptive MeshER software version 2, a mesh generation code written in C++ designed to convert structural data sets to realistic geometric meshes while preserving the underlying shapes. We present two example cases: 1) mesh generation at the subcellular scale as informed by electron tomography and 2) meshing a protein with a structure from x-ray crystallography. We further demonstrate that the meshes generated by the Geometry-preserving Adaptive MeshER software are suitable for use with numerical methods. Together, this collection of libraries and tools simplifies the process of constructing realistic geometric meshes from structural biology data.
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Affiliation(s)
- Christopher T Lee
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California.
| | - Justin G Laughlin
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
| | - John B Moody
- Department of Mathematics, University of California, San Diego, La Jolla, California
| | - Rommie E Amaro
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California
| | - J Andrew McCammon
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California
| | - Michael Holst
- Department of Mathematics, University of California, San Diego, La Jolla, California
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California.
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29
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Affiliation(s)
- Kristen M Harris
- Department of Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
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30
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Effects of Exercise on Long-Term Potentiation in Neuropsychiatric Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1228:439-451. [PMID: 32342476 DOI: 10.1007/978-981-15-1792-1_30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Various neuropsychiatric conditions, such as depression, Alzheimer's disease, and Parkinson's disease, demonstrate evidence of impaired long-term potentiation, a cellular correlate of episodic memory function. This chapter discusses the mechanistic effects of these neuropsychiatric conditions on long-term potentiation and how exercise may help to attenuate these detrimental effects.
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31
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Hippocampal Neurogenesis and Neural Circuit Formation in a Cuprizone-Induced Multiple Sclerosis Mouse Model. J Neurosci 2019; 40:447-458. [PMID: 31719166 DOI: 10.1523/jneurosci.0866-19.2019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 10/16/2019] [Accepted: 11/04/2019] [Indexed: 01/04/2023] Open
Abstract
Cognitive impairments are key features in multiple sclerosis (MS), a progressive disorder characterized by neuroinflammation-induced demyelination in the central nervous system. To understand the neural substrates that link demyelination to cognitive deficits in MS, we investigated hippocampal neurogenesis and synaptic connectivity of adult-born neurons, which play an essential role in cognitive function. The administration and withdrawal of the combination of cuprizone and rapamycin (Cup/Rap) in C57BL/6J male mice efficiently demyelinated and remyelinated the hippocampus, respectively. In the demyelinated hippocampus, neurogenesis was nearly absent in the dentate gyrus, which was due to inhibited proliferation of neural stem cells (NSCs). Specifically, radial glia-like type 1 NSCs were shifted from a proliferative state to a mitotically-quiescent state in the demyelinated hippocampus. In addition, dendritic spine densities of adult-born neurons were significantly decreased, indicating a reduction in synaptic connections between hippocampal newborn neurons and excitatory input neurons. Concomitant with hippocampal remyelination induced by withdrawal of Cup/Rap, proliferation of type 1 NSCs and dendritic spine densities of adult-born neurons reverted to normal in the hippocampus. Our study shows that proliferation of hippocampal NSCs and synaptic connectivity of adult-born neurons are inversely correlated with the level of demyelination, providing critical insight into hippocampal neurogenesis as a potential therapeutic target to treat cognitive deficits associated with MS.SIGNIFICANCE STATEMENT To identify the neural substrates that mediate cognitive dysfunctions associated with a majority of MS patients, we investigated hippocampal neurogenesis and structural development of adult-born neurons using a Cup/Rap model, which recapitulates the hippocampal demyelination that occurs in MS patients. A shift of NSCs from a proliferatively-active state to mitotically-quiescent state dramatically decreased neurogenesis in the demyelinated hippocampus. Formation of dendritic spines on newborn neurons was also impaired following demyelination. Interestingly, the altered neurogenesis and synaptic connectivity of newborn neurons were reversed to normal levels during remyelination. Thus, our study revealed reversible genesis and synaptic connectivity of adult-born neurons between the demyelinated and remyelinated hippocampus, suggesting hippocampal neurogenesis as a potential target to normalize cognitive impairments in MS patients.
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Sakimoto Y, Kida H, Mitsushima D. Temporal dynamics of learning-promoted synaptic diversity in CA1 pyramidal neurons. FASEB J 2019; 33:14382-14393. [PMID: 31689120 PMCID: PMC6894079 DOI: 10.1096/fj.201801893rrr] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although contextual learning requires plasticity at both excitatory and inhibitory (E/I) synapses in cornu ammonis 1 (CA1) neurons, the temporal dynamics across the neuronal population are poorly understood. Using an inhibitory avoidance task, we analyzed the dynamic changes in learning-induced E/I synaptic plasticity. The training strengthened GABAA receptor–mediated synapses within 1 min, peaked at 10 min, and lasted for over 60 min. The intracellular loop (Ser408−409) of GABAA receptor β3 subunit was also phosphorylated within 1 min of training. As the results of strengthening of α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptor–mediated synapses, CA1 pyramidal neurons exhibited broad diversity of E/I synaptic currents within 5 min. Moreover, presynaptic glutamate release probability at basal dendrites also increased within 5 min. To further quantify the diversified E/I synaptic currents, we calculated self-entropy (bit) for individual neurons. The neurons showed individual levels of the parameter, which rapidly increased within 1 min of training and maintained for over 60 min. These results suggest that learning-induced synaptic plasticity is critical immediately following encoding rather than during the retrieval phase of the learning. Understanding the temporal dynamics along with the quantification of synaptic diversity would be necessary to identify a failure point for learning-promoted plasticity in cognitive disorders.—Sakimoto, Y., Kida, H., Mitsushima, D. Temporal dynamics of learning-promoted synaptic diversity in CA1 pyramidal neurons.
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Affiliation(s)
- Yuya Sakimoto
- Department of Physiology, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Hiroyuki Kida
- Department of Physiology, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Dai Mitsushima
- Department of Physiology, Graduate School of Medicine, Yamaguchi University, Ube, Japan.,The Research Institute for Time Studies, Yamaguchi University, Yamaguchi, Japan
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Trotter JH, Hao J, Maxeiner S, Tsetsenis T, Liu Z, Zhuang X, Südhof TC. Synaptic neurexin-1 assembles into dynamically regulated active zone nanoclusters. J Cell Biol 2019; 218:2677-2698. [PMID: 31262725 PMCID: PMC6683742 DOI: 10.1083/jcb.201812076] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/10/2019] [Accepted: 05/30/2019] [Indexed: 12/04/2022] Open
Abstract
Neurexins are well-characterized presynaptic cell adhesion molecules that engage multifarious postsynaptic ligands and organize diverse synapse properties. However, the precise synaptic localization of neurexins remains enigmatic. Using super-resolution microscopy, we demonstrate that neurexin-1 forms discrete nanoclusters at excitatory synapses, revealing a novel organizational feature of synaptic architecture. Synapses generally contain a single nanocluster that comprises more than four neurexin-1 molecules and that also includes neurexin-2 and/or neurexin-3 isoforms. Moreover, we find that neurexin-1 is physiologically cleaved by ADAM10 similar to its ligand neuroligin-1, with ∼4-6% of neurexin-1 and ∼2-3% of neuroligin-1 present in the adult brain as soluble ectodomain proteins. Blocking ADAM10-mediated neurexin-1 cleavage dramatically increased the synaptic neurexin-1 content, thereby elevating the percentage of Homer1(+) excitatory synapses containing neurexin-1 nanoclusters from 40-50% to ∼80%, and doubling the number of neurexin-1 molecules per nanocluster. Taken together, our results reveal an unexpected nanodomain organization of synapses in which neurexin-1 is assembled into discrete presynaptic nanoclusters that are dynamically regulated via ectodomain cleavage.
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Affiliation(s)
- Justin H Trotter
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Junjie Hao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA
- Department of Physics, Harvard University, Cambridge, MA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA
| | - Stephan Maxeiner
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Theodoros Tsetsenis
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Zhihui Liu
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Xiaowei Zhuang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA
- Department of Physics, Harvard University, Cambridge, MA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
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Class IIa HDACs regulate learning and memory through dynamic experience-dependent repression of transcription. Nat Commun 2019; 10:3469. [PMID: 31375688 PMCID: PMC6677776 DOI: 10.1038/s41467-019-11409-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 07/13/2019] [Indexed: 01/08/2023] Open
Abstract
The formation of new memories requires transcription. However, the mechanisms that limit signaling of relevant gene programs in space and time for precision of information coding remain poorly understood. We found that, during learning, the cellular patterns of expression of early response genes (ERGs) are regulated by class IIa HDACs 4 and 5, transcriptional repressors that transiently enter neuronal nuclei from cytoplasm after sensory input. Mice lacking these repressors in the forebrain have abnormally broad experience-dependent expression of ERGs, altered synaptic architecture and function, elevated anxiety, and severely impaired memory. By acutely manipulating the nuclear activity of class IIa HDACs in behaving animals using a chemical-genetic technique, we further demonstrate that rapid induction of transcriptional programs is critical for memory acquisition but these programs may become dispensable when a stable memory is formed. These results provide new insights into the molecular basis of memory storage. The molecular mechanisms of memory storage remain poorly understood. In this study, authors describe a new mechanism that regulates the cellular patterns of early response gene signaling during learning via the recruitment of two functionally redundant nuclear repressors, class IIa histone deacetylases (HDACs) 4 and 5
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Sleep Deprivation by Exposure to Novel Objects Increases Synapse Density and Axon-Spine Interface in the Hippocampal CA1 Region of Adolescent Mice. J Neurosci 2019; 39:6613-6625. [PMID: 31263066 DOI: 10.1523/jneurosci.0380-19.2019] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/24/2019] [Accepted: 06/10/2019] [Indexed: 11/21/2022] Open
Abstract
Sleep has been hypothesized to rebalance overall synaptic strength after ongoing learning during waking leads to net synaptic potentiation. If so, because synaptic strength and size are correlated, synapses on average should be larger after wake and smaller after sleep. This prediction was recently confirmed in mouse cerebral cortex using serial block-face electron microscopy (SBEM). However, whether these findings extend to other brain regions is unknown. Moreover, sleep deprivation by gentle handling was reported to produce hippocampal spine loss, raising the question of whether synapse size and number are differentially affected by sleep and waking. Here we applied SBEM to measure axon-spine interface (ASI), the contact area between pre-synapse and post-synapse, and synapse density in CA1 stratum radiatum. Adolescent YFP-H mice were studied after 6-8 h of sleep (S = 6), spontaneous wake at night (W = 4) or wake enforced during the day by novelty exposure (EW = 4; males/females balanced). In each animal ≥425 ASIs were measured and synaptic vesicles were counted in ~100 synapses/mouse. Reconstructed dendrites included many small, nonperforated synapses and fewer large, perforated synapses. Relative to S, ASI sizes in perforated synapses shifted toward higher values after W and more so after EW. ASI sizes in nonperforated synapses grew after EW relative to S and W, and so did their density. ASI size correlated with presynaptic vesicle number but the proportion of readily available vesicles decreased after EW, suggesting presynaptic fatigue. Thus, CA1 synapses undergo changes consistent with sleep-dependent synaptic renormalization and their number increases after extended wake.SIGNIFICANCE STATEMENT Sleep benefits learning, memory consolidation, and the integration of new with old memories, but the underlying mechanisms remain highly debated. One hypothesis suggests that sleep's cognitive benefits stem from its ability to renormalize total synaptic strength, after ongoing learning during wake leads to net synaptic potentiation. Supporting evidence for this hypothesis mainly comes from the cerebral cortex, including the observation that cortical synapses are larger after wake and smaller after sleep. Using serial electron microscopy, we find here that sleep/wake synaptic changes consistent with sleep-dependent synaptic renormalization also occur in the CA1 region. Thus, the role of sleep in maintaining synaptic homeostasis may extend to the hippocampus, a key area for learning and synaptic plasticity.
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Letellier M, Levet F, Thoumine O, Goda Y. Differential role of pre- and postsynaptic neurons in the activity-dependent control of synaptic strengths across dendrites. PLoS Biol 2019; 17:e2006223. [PMID: 31166943 PMCID: PMC6576792 DOI: 10.1371/journal.pbio.2006223] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/17/2019] [Accepted: 05/17/2019] [Indexed: 01/07/2023] Open
Abstract
Neurons receive a large number of active synaptic inputs from their many presynaptic partners across their dendritic tree. However, little is known about how the strengths of individual synapses are controlled in balance with other synapses to effectively encode information while maintaining network homeostasis. This is in part due to the difficulty in assessing the activity of individual synapses with identified afferent and efferent connections for a synapse population in the brain. Here, to gain insights into the basic cellular rules that drive the activity-dependent spatial distribution of pre- and postsynaptic strengths across incoming axons and dendrites, we combine patch-clamp recordings with live-cell imaging of hippocampal pyramidal neurons in dissociated cultures and organotypic slices. Under basal conditions, both pre- and postsynaptic strengths cluster on single dendritic branches according to the identity of the presynaptic neurons, thus highlighting the ability of single dendritic branches to exhibit input specificity. Stimulating a single presynaptic neuron induces input-specific and dendritic branchwise spatial clustering of presynaptic strengths, which accompanies a widespread multiplicative scaling of postsynaptic strengths in dissociated cultures and heterosynaptic plasticity at distant synapses in organotypic slices. Our study provides evidence for a potential homeostatic mechanism by which the rapid changes in global or distant postsynaptic strengths compensate for input-specific presynaptic plasticity.
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Affiliation(s)
- Mathieu Letellier
- RIKEN Brain Science Institute, Wako, Saitama, Japan
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
- * E-mail: (ML); (YG)
| | - Florian Levet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
- Bordeaux Imaging Center, University of Bordeaux, Bordeaux, France
- Bordeaux Imaging Center, CNRS UMS 3420, Bordeaux, France
- Bordeaux Imaging Center, INSERM US04, Bordeaux, France
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
| | - Yukiko Goda
- RIKEN Center for Brain Science, Wako, Saitama, Japan
- * E-mail: (ML); (YG)
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Ryskamp D, Wu L, Wu J, Kim D, Rammes G, Geva M, Hayden M, Bezprozvanny I. Pridopidine stabilizes mushroom spines in mouse models of Alzheimer's disease by acting on the sigma-1 receptor. Neurobiol Dis 2019; 124:489-504. [PMID: 30594810 PMCID: PMC6363865 DOI: 10.1016/j.nbd.2018.12.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/12/2018] [Accepted: 12/26/2018] [Indexed: 12/19/2022] Open
Abstract
There is evidence that cognitive decline in Alzheimer's disease (AD) results from deficiencies in synaptic communication (e.g., loss of mushroom-shaped 'memory spines') and neurodegenerative processes. This might be treated with sigma-1 receptor (S1R) agonists, which are broadly neuroprotective and modulate synaptic plasticity. For example, we previously found that the mixed muscarinic/S1R agonist AF710B prevents mushroom spine loss in hippocampal cultures from APP knock-in (APP-KI) and presenilin-1-M146 V knock-in (PS1-KI) mice. We also found that the "dopaminergic stabilizer" pridopidine (structurally similar to the S1R agonist R(+)-3-PPP), is a high-affinity S1R agonist and is synaptoprotective in a mouse model of Huntington disease. Here we tested whether pridopidine and R(+)-3-PPP are synaptoprotective in models of AD and whether this requires S1R. We also examined the effects of pridopidine on long-term potentiation (LTP), endoplasmic reticulum calcium and neuronal store-operated calcium entry (nSOC) in spines, all of which are dysregulated in AD, contributing to synaptic pathology. We report here that pridopidine and 3-PPP protect mushroom spines from Aβ42 oligomer toxicity in primary WT hippocampal cultures from mice. Pridopidine also reversed LTP defects in hippocampal slices resulting from application of Aβ42 oligomers. Pridopidine and 3-PPP rescued mushroom spines in hippocampal cultures from APP-KI and PS1-KI mice. S1R knockdown from lenti-viral shRNA expression destabilized WT mushroom spines and prevented the synaptoprotective effects of pridopidine in PS1-KI cultures. Knockout of PS1/2 destabilized mushroom spines and pridopidine was unable to prevent this. Pridopidine lowered endoplasmic reticulum calcium levels in WT, PS1-KO, PS1-KI and PS2 KO neurons, but not in PS1/2 KO neurons. S1R was required for pridopidine to enhance spine nSOC in PS1-KI neurons. Pridopidine was unable to rescue PS1-KI mushroom spines during pharmacological or genetic inhibition of nSOC. Oral pridopidine treatment rescued mushroom spines in vivo in aged PS1-KI-GFP mice. Pridopidine stabilizes mushroom spines in mouse models of AD and this requires S1R, endoplasmic reticulum calcium leakage through PS1/2 and nSOC. Thus, pridopidine may be useful to explore for the treatment of AD.
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Affiliation(s)
- Daniel Ryskamp
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lili Wu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jun Wu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Dabin Kim
- Department of Anesthesiology and Intensive Care, Technische Universität München, Munich 81675, Germany
| | - Gerhard Rammes
- Department of Anesthesiology and Intensive Care, Technische Universität München, Munich 81675, Germany.
| | | | | | - Ilya Bezprozvanny
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.
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Chirillo MA, Waters MS, Lindsey LF, Bourne JN, Harris KM. Local resources of polyribosomes and SER promote synapse enlargement and spine clustering after long-term potentiation in adult rat hippocampus. Sci Rep 2019; 9:3861. [PMID: 30846859 PMCID: PMC6405867 DOI: 10.1038/s41598-019-40520-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 02/07/2019] [Indexed: 12/11/2022] Open
Abstract
Synapse clustering facilitates circuit integration, learning, and memory. Long-term potentiation (LTP) of mature neurons produces synapse enlargement balanced by fewer spines, raising the question of how clusters form despite this homeostatic regulation of total synaptic weight. Three-dimensional reconstruction from serial section electron microscopy (3DEM) revealed the shapes and distributions of smooth endoplasmic reticulum (SER) and polyribosomes, subcellular resources important for synapse enlargement and spine outgrowth. Compared to control stimulation, synapses were enlarged two hours after LTP on resource-rich spines containing polyribosomes (4% larger than control) or SER (15% larger). SER in spines shifted from a single tubule to complex spine apparatus after LTP. Negligible synapse enlargement (0.6%) occurred on resource-poor spines lacking SER and polyribosomes. Dendrites were divided into discrete synaptic clusters surrounded by asynaptic segments. Spine density was lowest in clusters having only resource-poor spines, especially following LTP. In contrast, resource-rich spines preserved neighboring resource-poor spines and formed larger clusters with elevated total synaptic weight following LTP. These clusters also had more shaft SER branches, which could sequester cargo locally to support synapse growth and spinogenesis. Thus, resources appear to be redistributed to synaptic clusters with LTP-related synapse enlargement while homeostatic regulation suppressed spine outgrowth in resource-poor synaptic clusters.
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Affiliation(s)
- Michael A Chirillo
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas, 78712, USA.,Fulbright U.S. Scholar Program, University of Belgrade, Studentski trg 1, Belgrade, 11000, Serbia
| | - Mikayla S Waters
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas, 78712, USA.,McGovern Medical School in Houston, 6431 Fannin St., Houston, TX, 77030, USA
| | - Laurence F Lindsey
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas, 78712, USA.,Google Seattle, Seattle, Washington, 98103, USA
| | - Jennifer N Bourne
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas, 78712, USA.,Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, 80045, USA
| | - Kristen M Harris
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas, 78712, USA.
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Zhang Y, He F, Hua T, Sun Q. Green tea polyphenols ameliorate ethanol-induced spatial learning and memory impairments by enhancing hippocampus NMDAR1 expression and CREB activity in rats. Neuroreport 2018; 29:1564-1570. [PMID: 30371539 DOI: 10.1097/wnr.0000000000001152] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The current research probed into the effects of green tea polyphenols (GTPs) on ethanol-induced spatial learning and memory impairments and inquired the potential molecular mechanism in rats. Thirty 8-week-old male Sprague-Dawley rats were randomly divided into three groups. The control group (control, n=10), ethanol group (ethanol, n=10), and GTPs intervention group (GTP, n=10) received gavage administration of saline, ethanol, and ethanol-GTP solution, respectively, for 8 weeks. Morris water maze was applied to assess the spatial learning and memory function of rats in each group at the last week of treatment. There was no dramatic change in body weight of rats in the different groups. Compared with rats in the control group, 8-week ethanol gavaged rats showed increased escape latency period and decreased time in the target quadrant. Moreover, 8-week ethanol gavage decreased the density of pyramidal layer neurons, expression of NMDAR1, and CREB phosphorylation in the hippocampus region. In contrast, GTP intervention decreased escape latency period and increased the time in the target quadrant, the density of pyramidal layer neurons, expression of NMDAR1, and CREB phosphorylation in the hippocampus region. The current findings indicated that GTP intervention can improve ethanol-induced spatial learning and memory impairments in rats after ethanol withdrawal, which is related to the upregulated density of pyramidal layer neurons, expression of NMDAR1, and CREB phosphorylation in the hippocampus region.
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Affiliation(s)
- Yong Zhang
- Physiology Laboratory of College of Life Sciences
| | - Fenfen He
- Physiology Laboratory of College of Life Sciences
| | - Tianmiao Hua
- Neurobiology Laboratory of College of Life Sciences, Anhui Normal University, Wuhu, People's Republic of China
| | - Qingyan Sun
- Physiology Laboratory of College of Life Sciences
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Kubota Y, Sohn J, Kawaguchi Y. Large Volume Electron Microscopy and Neural Microcircuit Analysis. Front Neural Circuits 2018; 12:98. [PMID: 30483066 PMCID: PMC6240581 DOI: 10.3389/fncir.2018.00098] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/17/2018] [Indexed: 12/23/2022] Open
Abstract
One recent technical innovation in neuroscience is microcircuit analysis using three-dimensional reconstructions of neural elements with a large volume Electron microscopy (EM) data set. Large-scale data sets are acquired with newly-developed electron microscope systems such as automated tape-collecting ultramicrotomy (ATUM) with scanning EM (SEM), serial block-face EM (SBEM) and focused ion beam-SEM (FIB-SEM). Currently, projects are also underway to develop computer applications for the registration and segmentation of the serially-captured electron micrographs that are suitable for analyzing large volume EM data sets thoroughly and efficiently. The analysis of large volume data sets can bring innovative research results. These recently available techniques promote our understanding of the functional architecture of the brain.
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Affiliation(s)
- Yoshiyuki Kubota
- Division of Cerebral Circuitry, National Institute for Physiological Sciences (NIPS), Okazaki, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Jaerin Sohn
- Division of Cerebral Circuitry, National Institute for Physiological Sciences (NIPS), Okazaki, Japan
- Research Fellow of Japan Society for the Promotion of Science (JSPS), Tokyo, Japan
| | - Yasuo Kawaguchi
- Division of Cerebral Circuitry, National Institute for Physiological Sciences (NIPS), Okazaki, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
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41
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Item-Place Encoding Through Hippocampal Long-Term Depression. HANDBOOK OF OBJECT NOVELTY RECOGNITION 2018. [DOI: 10.1016/b978-0-12-812012-5.00019-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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