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Chater TE, Eggl MF, Goda Y, Tchumatchenko T. Competitive processes shape multi-synapse plasticity along dendritic segments. Nat Commun 2024; 15:7572. [PMID: 39217140 PMCID: PMC11365941 DOI: 10.1038/s41467-024-51919-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 08/21/2024] [Indexed: 09/04/2024] Open
Abstract
Neurons receive thousands of inputs onto their dendritic arbour, where individual synapses undergo activity-dependent plasticity. Long-lasting changes in postsynaptic strengths correlate with changes in spine head volume. The magnitude and direction of such structural plasticity - potentiation (sLTP) and depression (sLTD) - depend upon the number and spatial distribution of stimulated synapses. However, how neurons allocate resources to implement synaptic strength changes across space and time amongst neighbouring synapses remains unclear. Here we combined experimental and modelling approaches to explore the elementary processes underlying multi-spine plasticity. We used glutamate uncaging to induce sLTP at varying number of synapses sharing the same dendritic branch, and we built a model incorporating a dual role Ca2+-dependent component that induces spine growth or shrinkage. Our results suggest that competition among spines for molecular resources is a key driver of multi-spine plasticity and that spatial distance between simultaneously stimulated spines impacts the resulting spine dynamics.
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Affiliation(s)
- Thomas E Chater
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Maximilian F Eggl
- Institute of Experimental Epileptology and Cognition Research, University of Bonn Medical Center, Venusberg-Campus 1, 53127, Bonn, Germany
- Institute of Neuroscience, CSIC-UMH, Alicante, Spain
| | - Yukiko Goda
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako-shi, Saitama, Japan.
- Synapse Biology Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami-gun, Okinawa, Japan.
| | - Tatjana Tchumatchenko
- Institute of Experimental Epileptology and Cognition Research, University of Bonn Medical Center, Venusberg-Campus 1, 53127, Bonn, Germany.
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2
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Rasetto NB, Giacomini D, Berardino AA, Waichman TV, Beckel MS, Di Bella DJ, Brown J, Davies-Sala MG, Gerhardinger C, Lie DC, Arlotta P, Chernomoretz A, Schinder AF. Transcriptional dynamics orchestrating the development and integration of neurons born in the adult hippocampus. SCIENCE ADVANCES 2024; 10:eadp6039. [PMID: 39028813 PMCID: PMC11259177 DOI: 10.1126/sciadv.adp6039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Accepted: 06/13/2024] [Indexed: 07/21/2024]
Abstract
The adult hippocampus generates new granule cells (aGCs) with functional capabilities that convey unique forms of plasticity to the preexisting circuits. While early differentiation of adult radial glia-like cells (RGLs) has been studied extensively, the molecular mechanisms guiding the maturation of postmitotic neurons remain unknown. Here, we used a precise birthdating strategy to study aGC differentiation using single-nuclei RNA sequencing. Transcriptional profiling revealed a continuous trajectory from RGLs to mature aGCs, with multiple immature stages bearing increasing levels of effector genes supporting growth, excitability, and synaptogenesis. Analysis of differential gene expression, pseudo-time trajectory, and transcription factors (TFs) revealed critical transitions defining four cellular states: quiescent RGLs, proliferative progenitors, immature aGCs, and mature aGCs. Becoming mature aGCs involved a transcriptional switch that shuts down pathways promoting cell growth, such SoxC TFs, to activate programs that likely control neuronal homeostasis. aGCs overexpressing Sox4 or Sox11 remained immature. Our results unveil precise molecular mechanisms driving adult RGLs through the pathway of neuronal differentiation.
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Affiliation(s)
- Natalí B. Rasetto
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Neuronal Plasticity, Leloir Institute, Buenos Aires, Argentina
| | - Damiana Giacomini
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Neuronal Plasticity, Leloir Institute, Buenos Aires, Argentina
| | - Ariel A. Berardino
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Integrative Systems Biology, Leloir Institute, Buenos Aires, Argentina
| | - Tomás Vega Waichman
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Integrative Systems Biology, Leloir Institute, Buenos Aires, Argentina
| | - Maximiliano S. Beckel
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Integrative Systems Biology, Leloir Institute, Buenos Aires, Argentina
| | - Daniela J. Di Bella
- Department of Stem Cells and Regenerative Biology, Harvard University and Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Juliana Brown
- Department of Stem Cells and Regenerative Biology, Harvard University and Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - M. Georgina Davies-Sala
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Neuronal Plasticity, Leloir Institute, Buenos Aires, Argentina
| | - Chiara Gerhardinger
- Department of Stem Cells and Regenerative Biology, Harvard University and Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Dieter Chichung Lie
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Paola Arlotta
- Department of Stem Cells and Regenerative Biology, Harvard University and Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Ariel Chernomoretz
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Integrative Systems Biology, Leloir Institute, Buenos Aires, Argentina
- University of Buenos Aires, School of Science, Phys Dept and INFINA (CONICET-UBA), Buenos Aires, Argentina
| | - Alejandro F. Schinder
- Instituto de Investigaciones Biomédicas de Buenos Aires (IIBBA) – CONICET, Buenos Aires, Argentina
- Laboratory of Neuronal Plasticity, Leloir Institute, Buenos Aires, Argentina
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3
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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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4
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Bird AD, Cuntz H, Jedlicka P. Robust and consistent measures of pattern separation based on information theory and demonstrated in the dentate gyrus. PLoS Comput Biol 2024; 20:e1010706. [PMID: 38377108 PMCID: PMC10906873 DOI: 10.1371/journal.pcbi.1010706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/01/2024] [Accepted: 12/13/2023] [Indexed: 02/22/2024] Open
Abstract
Pattern separation is a valuable computational function performed by neuronal circuits, such as the dentate gyrus, where dissimilarity between inputs is increased, reducing noise and increasing the storage capacity of downstream networks. Pattern separation is studied from both in vivo experimental and computational perspectives and, a number of different measures (such as orthogonalisation, decorrelation, or spike train distance) have been applied to quantify the process of pattern separation. However, these are known to give conclusions that can differ qualitatively depending on the choice of measure and the parameters used to calculate it. We here demonstrate that arbitrarily increasing sparsity, a noticeable feature of dentate granule cell firing and one that is believed to be key to pattern separation, typically leads to improved classical measures for pattern separation even, inappropriately, up to the point where almost all information about the inputs is lost. Standard measures therefore both cannot differentiate between pattern separation and pattern destruction, and give results that may depend on arbitrary parameter choices. We propose that techniques from information theory, in particular mutual information, transfer entropy, and redundancy, should be applied to penalise the potential for lost information (often due to increased sparsity) that is neglected by existing measures. We compare five commonly-used measures of pattern separation with three novel techniques based on information theory, showing that the latter can be applied in a principled way and provide a robust and reliable measure for comparing the pattern separation performance of different neurons and networks. We demonstrate our new measures on detailed compartmental models of individual dentate granule cells and a dentate microcircuit, and show how structural changes associated with epilepsy affect pattern separation performance. We also demonstrate how our measures of pattern separation can predict pattern completion accuracy. Overall, our measures solve a widely acknowledged problem in assessing the pattern separation of neural circuits such as the dentate gyrus, as well as the cerebellum and mushroom body. Finally we provide a publicly available toolbox allowing for easy analysis of pattern separation in spike train ensembles.
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Affiliation(s)
- Alexander D. Bird
- Computer-Based Modelling in the field of 3R Animal Protection, ICAR3R, Faculty of Medicine, Justus Liebig University, Giessen, Germany
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with the Max Planck Society, Frankfurt-am-Main, Germany
- Frankfurt Institute for Advanced Studies, Frankfurt-am-Main, Germany
- Translational Neuroscience Network Giessen, Germany
| | - Hermann Cuntz
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with the Max Planck Society, Frankfurt-am-Main, Germany
- Frankfurt Institute for Advanced Studies, Frankfurt-am-Main, Germany
- Translational Neuroscience Network Giessen, Germany
| | - Peter Jedlicka
- Computer-Based Modelling in the field of 3R Animal Protection, ICAR3R, Faculty of Medicine, Justus Liebig University, Giessen, Germany
- Translational Neuroscience Network Giessen, Germany
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5
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Rasetto NB, Giacomini D, Berardino AA, Waichman TV, Beckel MS, Di Bella DJ, Brown J, Davies-Sala MG, Gerhardinger C, Lie DC, Arlotta P, Chernomoretz A, Schinder AF. Transcriptional dynamics orchestrating the development and integration of neurons born in the adult hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.03.565477. [PMID: 38260428 PMCID: PMC10802403 DOI: 10.1101/2023.11.03.565477] [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
The adult hippocampus generates new granule cells (aGCs) that exhibit distinct functional capabilities along development, conveying a unique form of plasticity to the preexisting circuits. While early differentiation of adult radial glia-like neural stem cells (RGL) has been studied extensively, the molecular mechanisms guiding the maturation of postmitotic neurons remain unknown. Here, we used a precise birthdating strategy to follow newborn aGCs along differentiation using single-nuclei RNA sequencing (snRNA-seq). Transcriptional profiling revealed a continuous trajectory from RGLs to mature aGCs, with multiple sequential immature stages bearing increasing levels of effector genes supporting growth, excitability and synaptogenesis. Remarkably, four discrete cellular states were defined by the expression of distinct sets of transcription factors (TFs): quiescent neural stem cells, proliferative progenitors, postmitotic immature aGCs, and mature aGCs. The transition from immature to mature aCGs involved a transcriptional switch that shutdown molecular cascades promoting cell growth, such as the SoxC family of TFs, to activate programs controlling neuronal homeostasis. Indeed, aGCs overexpressing Sox4 or Sox11 remained stalled at the immature state. Our results unveil precise molecular mechanisms driving adult neural stem cells through the pathway of neuronal differentiation.
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6
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Cao YY, Wu LL, Li XN, Yuan YL, Zhao WW, Qi JX, Zhao XY, Ward N, Wang J. Molecular Mechanisms of AMPA Receptor Trafficking in the Nervous System. Int J Mol Sci 2023; 25:111. [PMID: 38203282 PMCID: PMC10779435 DOI: 10.3390/ijms25010111] [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: 11/24/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024] Open
Abstract
Synaptic plasticity enhances or reduces connections between neurons, affecting learning and memory. Postsynaptic AMPARs mediate greater than 90% of the rapid excitatory synaptic transmission in glutamatergic neurons. The number and subunit composition of AMPARs are fundamental to synaptic plasticity and the formation of entire neural networks. Accordingly, the insertion and functionalization of AMPARs at the postsynaptic membrane have become a core issue related to neural circuit formation and information processing in the central nervous system. In this review, we summarize current knowledge regarding the related mechanisms of AMPAR expression and trafficking. The proteins related to AMPAR trafficking are discussed in detail, including vesicle-related proteins, cytoskeletal proteins, synaptic proteins, and protein kinases. Furthermore, significant emphasis was placed on the pivotal role of the actin cytoskeleton, which spans throughout the entire transport process in AMPAR transport, indicating that the actin cytoskeleton may serve as a fundamental basis for AMPAR trafficking. Additionally, we summarize the proteases involved in AMPAR post-translational modifications. Moreover, we provide an overview of AMPAR transport and localization to the postsynaptic membrane. Understanding the assembly, trafficking, and dynamic synaptic expression mechanisms of AMPAR may provide valuable insights into the cognitive decline associated with neurodegenerative diseases.
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Affiliation(s)
- Yi-Yang Cao
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Ling-Ling Wu
- School of Medicine, Shanghai University, Shanghai 200444, China;
| | - Xiao-Nan Li
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Yu-Lian Yuan
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Wan-Wei Zhao
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Jing-Xuan Qi
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Xu-Yu Zhao
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Natalie Ward
- Medical Laboratory, Exceptional Community Hospital, 19060 N John Wayne Pkwy, Maricopa, AZ 85139, USA;
| | - Jiao Wang
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
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7
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Kourosh-Arami M, Komaki A, Gholami M, Marashi SH, Hejazi S. Heterosynaptic plasticity-induced modulation of synapses. J Physiol Sci 2023; 73:33. [PMID: 38057729 DOI: 10.1186/s12576-023-00893-1] [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: 06/17/2023] [Accepted: 11/27/2023] [Indexed: 12/08/2023]
Abstract
Plasticity is a common feature of synapses that is stated in different ways and occurs through several mechanisms. The regular action of the brain needs to be balanced in several neuronal and synaptic features, one of which is synaptic plasticity. The different homeostatic processes, including the balance between excitation/inhibition or homeostasis of synaptic weights at the single-neuron level, may obtain this. Homosynaptic Hebbian-type plasticity causes associative alterations of synapses. Both homosynaptic and heterosynaptic plasticity characterize the corresponding aspects of adjustable synapses, and both are essential for the regular action of neural systems and their plastic synapses.In this review, we will compare homo- and heterosynaptic plasticity and the main factors affecting the direction of plastic changes. This review paper will also discuss the diverse functions of the different kinds of heterosynaptic plasticity and their properties. We argue that a complementary system of heterosynaptic plasticity demonstrates an essential cellular constituent for homeostatic modulation of synaptic weights and neuronal activity.
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Affiliation(s)
- Masoumeh Kourosh-Arami
- Department of Neuroscience, School of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Alireza Komaki
- Department of Neuroscience, School of Science and Advanced Technologies in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Masoumeh Gholami
- Department of Physiology, Medical College, Arak University of Medical Sciences, Arak, Iran
| | | | - Sara Hejazi
- Department of Industrial Engineering & Management Systems, University of Central Florida, Orlando, USA
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8
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Kastellakis G, Tasciotti S, Pandi I, Poirazi P. The dendritic engram. Front Behav Neurosci 2023; 17:1212139. [PMID: 37576932 PMCID: PMC10412934 DOI: 10.3389/fnbeh.2023.1212139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/11/2023] [Indexed: 08/15/2023] Open
Abstract
Accumulating evidence from a wide range of studies, including behavioral, cellular, molecular and computational findings, support a key role of dendrites in the encoding and recall of new memories. Dendrites can integrate synaptic inputs in non-linear ways, provide the substrate for local protein synthesis and facilitate the orchestration of signaling pathways that regulate local synaptic plasticity. These capabilities allow them to act as a second layer of computation within the neuron and serve as the fundamental unit of plasticity. As such, dendrites are integral parts of the memory engram, namely the physical representation of memories in the brain and are increasingly studied during learning tasks. Here, we review experimental and computational studies that support a novel, dendritic view of the memory engram that is centered on non-linear dendritic branches as elementary memory units. We highlight the potential implications of dendritic engrams for the learning and memory field and discuss future research directions.
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Affiliation(s)
- George Kastellakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Greece
| | - Simone Tasciotti
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Greece
| | - Ioanna Pandi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Greece
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Greece
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9
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Ye L, Shu S, Jia J, Sun M, Xu S, Bao X, Bian H, Liu Y, Zhang M, Zhu X, Bai F, Xu Y. Absent in melanoma 2 mediates aging-related cognitive dysfunction by acting on complement-dependent microglial phagocytosis. Aging Cell 2023; 22:e13860. [PMID: 37177836 PMCID: PMC10352562 DOI: 10.1111/acel.13860] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/27/2023] [Accepted: 04/03/2023] [Indexed: 05/15/2023] Open
Abstract
Pattern separation (PS) dysfunction is a type of cognitive impairment that presents early during the aging process, and this deficit has been attributed to structural and functional alterations in the dentate gyrus (DG) of the hippocampus. Absent in melanoma 2 (AIM2) is an essential component of the inflammasome. However, whether AIM2 plays a role in aging-associated cognitive dysfunction remains unclear. Here, we found that PS function was impaired in aging mice and was accompanied by marked synaptic loss and increased expression of AIM2 in the DG. Subsequently, we used an AIM2 overexpression virus and mice with AIM2 deletion to investigate the role of AIM2 in regulating PS function and synaptic plasticity and the mechanisms involved. Our study revealed that AIM2 regulates microglial activation during synaptic pruning in the DG region via the complement pathway, leading to impaired synaptic plasticity and PS function in aging mice. These results suggest a critical role for AIM2 in regulating synaptic plasticity and PS function and provide a new direction for ameliorating aging-associated cognitive dysfunction.
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Affiliation(s)
- Lei Ye
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Shu Shu
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Junqiu Jia
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Min Sun
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Siyi Xu
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Xinyu Bao
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Huijie Bian
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Yi Liu
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Meijuan Zhang
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Xiaolei Zhu
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Feng Bai
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
| | - Yun Xu
- Department of Neurology, Nanjing Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Institute of Translational Medicine for Brain Critical Diseases, Medical SchoolNanjing UniversityNanjingChina
- Jiangsu Key Laboratory for Molecular MedicineMedical School of Nanjing UniversityNanjingChina
- Jiangsu Provincial Key Discipline of NeurologyNanjingChina
- Nanjing Neurology Medical CenterNanjingChina
- Nanjing Neuropsychiatry Clinic Medical CenterNanjingChina
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10
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Jungenitz T, Bird A, Engelhardt M, Jedlicka P, Schwarzacher SW, Deller T. Structural plasticity of the axon initial segment in rat hippocampal granule cells following high frequency stimulation and LTP induction. Front Neuroanat 2023; 17:1125623. [PMID: 37090138 PMCID: PMC10113456 DOI: 10.3389/fnana.2023.1125623] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/20/2023] [Indexed: 04/25/2023] Open
Abstract
The axon initial segment (AIS) is the site of action potential initiation and important for the integration of synaptic input. Length and localization of the AIS are dynamic, modulated by afferent activity and contribute to the homeostatic control of neuronal excitability. Synaptopodin is a plasticity-related protein expressed by the majority of telencephalic neurons. It is required for the formation of cisternal organelles within the AIS and an excellent marker to identify these enigmatic organelles at the light microscopic level. Here we applied 2 h of high frequency stimulation of the medial perforant path in rats in vivo to induce a strong long-term potentiation of dentate gyrus granule cells. Immunolabeling for βIV-spectrin and synaptopodin were performed to study structural changes of the AIS and its cisternal organelles. Three-dimensional analysis of the AIS revealed a shortening of the AIS and a corresponding reduction of the number of synaptopodin clusters. These data demonstrate a rapid structural plasticity of the AIS and its cisternal organelles to strong stimulation, indicating a homeostatic response of the entire AIS compartment.
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Affiliation(s)
- Tassilo Jungenitz
- Institute of Clinical Neuroanatomy, Goethe University Frankfurt, Frankfurt am Main, Germany
- *Correspondence: Tassilo Jungenitz,
| | - Alexander Bird
- Interdisciplinary Centre for 3Rs in Animal Research, Justus Liebig University Giessen, Giessen, Germany
| | - Maren Engelhardt
- Institute of Anatomy and Cell Biology, Johannes Kepler University Linz, Linz, Austria
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Goethe University Frankfurt, Frankfurt am Main, Germany
- Interdisciplinary Centre for 3Rs in Animal Research, Justus Liebig University Giessen, Giessen, Germany
| | | | - Thomas Deller
- Institute of Clinical Neuroanatomy, Goethe University Frankfurt, Frankfurt am Main, Germany
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11
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Fölsz O, Trouche S, Croset V. Adult-born neurons add flexibility to hippocampal memories. Front Neurosci 2023; 17:1128623. [PMID: 36875670 PMCID: PMC9975346 DOI: 10.3389/fnins.2023.1128623] [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: 12/20/2022] [Accepted: 01/30/2023] [Indexed: 02/17/2023] Open
Abstract
Although most neurons are generated embryonically, neurogenesis is maintained at low rates in specific brain areas throughout adulthood, including the dentate gyrus of the mammalian hippocampus. Episodic-like memories encoded in the hippocampus require the dentate gyrus to decorrelate similar experiences by generating distinct neuronal representations from overlapping inputs (pattern separation). Adult-born neurons integrating into the dentate gyrus circuit compete with resident mature cells for neuronal inputs and outputs, and recruit inhibitory circuits to limit hippocampal activity. They display transient hyperexcitability and hyperplasticity during maturation, making them more likely to be recruited by any given experience. Behavioral evidence suggests that adult-born neurons support pattern separation in the rodent dentate gyrus during encoding, and they have been proposed to provide a temporal stamp to memories encoded in close succession. The constant addition of neurons gradually degrades old connections, promoting generalization and ultimately forgetting of remote memories in the hippocampus. This makes space for new memories, preventing saturation and interference. Overall, a small population of adult-born neurons appears to make a unique contribution to hippocampal information encoding and removal. Although several inconsistencies regarding the functional relevance of neurogenesis remain, in this review we argue that immature neurons confer a unique form of transience on the dentate gyrus that complements synaptic plasticity to help animals flexibly adapt to changing environments.
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Affiliation(s)
- Orsolya Fölsz
- Department of Biosciences, Durham University, Durham, United Kingdom.,MSc in Neuroscience Programme, University of Oxford, Oxford, United Kingdom
| | - Stéphanie Trouche
- Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Vincent Croset
- Department of Biosciences, Durham University, Durham, United Kingdom
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12
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Vicencio-Jimenez S, Villalobos M, Maldonado PE, Vergara RC. The Energy Homeostasis Principle: A Naturalistic Approach to Explain the Emergence of Behavior. Front Syst Neurosci 2022; 15:782781. [PMID: 35069133 PMCID: PMC8770284 DOI: 10.3389/fnsys.2021.782781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
It is still elusive to explain the emergence of behavior and understanding based on its neural mechanisms. One renowned proposal is the Free Energy Principle (FEP), which uses an information-theoretic framework derived from thermodynamic considerations to describe how behavior and understanding emerge. FEP starts from a whole-organism approach, based on mental states and phenomena, mapping them into the neuronal substrate. An alternative approach, the Energy Homeostasis Principle (EHP), initiates a similar explanatory effort but starts from single-neuron phenomena and builds up to whole-organism behavior and understanding. In this work, we further develop the EHP as a distinct but complementary vision to FEP and try to explain how behavior and understanding would emerge from the local requirements of the neurons. Based on EHP and a strict naturalist approach that sees living beings as physical and deterministic systems, we explain scenarios where learning would emerge without the need for volition or goals. Given these starting points, we state several considerations of how we see the nervous system, particularly the role of the function, purpose, and conception of goal-oriented behavior. We problematize these conceptions, giving an alternative teleology-free framework in which behavior and, ultimately, understanding would still emerge. We reinterpret neural processing by explaining basic learning scenarios up to simple anticipatory behavior. Finally, we end the article with an evolutionary perspective of how this non-goal-oriented behavior appeared. We acknowledge that our proposal, in its current form, is still far from explaining the emergence of understanding. Nonetheless, we set the ground for an alternative neuron-based framework to ultimately explain understanding.
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Affiliation(s)
- Sergio Vicencio-Jimenez
- The Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Mario Villalobos
- Escuela de Psicología y Filosofía, Universidad de Tarapacá, Arica, Chile
| | - Pedro E. Maldonado
- Laboratorio de Neurosistemas, Departamento de Neurociencia & BNI, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Rodrigo C. Vergara
- Departamento de Kinesiología, Facultad de Artes y Educación Física, Universidad Metropolitana de las Ciencias de la Educación, Ñuñoa, Chile
- *Correspondence: Rodrigo C. Vergara
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13
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Jenks KR, Tsimring K, Ip JPK, Zepeda JC, Sur M. Heterosynaptic Plasticity and the Experience-Dependent Refinement of Developing Neuronal Circuits. Front Neural Circuits 2021; 15:803401. [PMID: 34949992 PMCID: PMC8689143 DOI: 10.3389/fncir.2021.803401] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/15/2021] [Indexed: 01/01/2023] Open
Abstract
Neurons remodel the structure and strength of their synapses during critical periods of development in order to optimize both perception and cognition. Many of these developmental synaptic changes are thought to occur through synapse-specific homosynaptic forms of experience-dependent plasticity. However, homosynaptic plasticity can also induce or contribute to the plasticity of neighboring synapses through heterosynaptic interactions. Decades of research in vitro have uncovered many of the molecular mechanisms of heterosynaptic plasticity that mediate local compensation for homosynaptic plasticity, facilitation of further bouts of plasticity in nearby synapses, and cooperative induction of plasticity by neighboring synapses acting in concert. These discoveries greatly benefited from new tools and technologies that permitted single synapse imaging and manipulation of structure, function, and protein dynamics in living neurons. With the recent advent and application of similar tools for in vivo research, it is now feasible to explore how heterosynaptic plasticity contribute to critical periods and the development of neuronal circuits. In this review, we will first define the forms heterosynaptic plasticity can take and describe our current understanding of their molecular mechanisms. Then, we will outline how heterosynaptic plasticity may lead to meaningful refinement of neuronal responses and observations that suggest such mechanisms are indeed at work in vivo. Finally, we will use a well-studied model of cortical plasticity—ocular dominance plasticity during a critical period of visual cortex development—to highlight the molecular overlap between heterosynaptic and developmental forms of plasticity, and suggest potential avenues of future research.
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Affiliation(s)
- Kyle R Jenks
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Katya Tsimring
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Jacque Pak Kan Ip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Jose C Zepeda
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Mriganka Sur
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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14
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Kourosh-Arami M, Hosseini N, Komaki A. Brain is modulated by neuronal plasticity during postnatal development. J Physiol Sci 2021; 71:34. [PMID: 34789147 PMCID: PMC10716960 DOI: 10.1186/s12576-021-00819-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 10/27/2021] [Indexed: 11/10/2022]
Abstract
Neuroplasticity is referred to the ability of the nervous system to change its structure or functions as a result of former stimuli. It is a plausible mechanism underlying a dynamic brain through adaptation processes of neural structure and activity patterns. Nevertheless, it is still unclear how the plastic neural systems achieve and maintain their equilibrium. Additionally, the alterations of balanced brain dynamics under different plasticity rules have not been explored either. Therefore, the present article primarily aims to review recent research studies regarding homosynaptic and heterosynaptic neuroplasticity characterized by the manipulation of excitatory and inhibitory synaptic inputs. Moreover, it attempts to understand different mechanisms related to the main forms of synaptic plasticity at the excitatory and inhibitory synapses during the brain development processes. Hence, this study comprised surveying those articles published since 1988 and available through PubMed, Google Scholar and science direct databases on a keyword-based search paradigm. All in all, the study results presented extensive and corroborative pieces of evidence for the main types of plasticity, including the long-term potentiation (LTP) and long-term depression (LTD) of the excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs).
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Affiliation(s)
- Masoumeh Kourosh-Arami
- Department of Neuroscience, School of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Nasrin Hosseini
- Neuroscience Research Center, Iran University of Medical Sciences, Tehran, Iran.
| | - Alireza Komaki
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
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15
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Domínguez-Rivas E, Ávila-Muñoz E, Schwarzacher SW, Zepeda A. Adult hippocampal neurogenesis in the context of lipopolysaccharide-induced neuroinflammation: A molecular, cellular and behavioral review. Brain Behav Immun 2021; 97:286-302. [PMID: 34174334 DOI: 10.1016/j.bbi.2021.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 06/17/2021] [Accepted: 06/19/2021] [Indexed: 12/17/2022] Open
Abstract
The continuous generation of new neurons occurs in at least two well-defined niches in the adult rodent brain. One of these areas is the subgranular zone of the dentate gyrus (DG) in the hippocampus. While the DG is associated with contextual and spatial learning and memory, hippocampal neurogenesis is necessary for pattern separation. Hippocampal neurogenesis begins with the activation of neural stem cells and culminates with the maturation and functional integration of a portion of the newly generated glutamatergic neurons into the hippocampal circuits. The neurogenic process is continuously modulated by intrinsic factors, one of which is neuroinflammation. The administration of lipopolysaccharide (LPS) has been widely used as a model of neuroinflammation and has yielded a body of evidence for unveiling the detrimental impact of inflammation upon the neurogenic process. This work aims to provide a comprehensive overview of the current knowledge on the effects of the systemic and central administration of LPS upon the different stages of neurogenesis and discuss their effects at the molecular, cellular, and behavioral levels.
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Affiliation(s)
- Eduardo Domínguez-Rivas
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Evangelina Ávila-Muñoz
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Stephan W Schwarzacher
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Angélica Zepeda
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico; Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt am Main, Germany.
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16
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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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17
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Bird AD, Jedlicka P, Cuntz H. Dendritic normalisation improves learning in sparsely connected artificial neural networks. PLoS Comput Biol 2021; 17:e1009202. [PMID: 34370727 PMCID: PMC8407571 DOI: 10.1371/journal.pcbi.1009202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 08/31/2021] [Accepted: 06/19/2021] [Indexed: 11/25/2022] Open
Abstract
Artificial neural networks, taking inspiration from biological neurons, have become an invaluable tool for machine learning applications. Recent studies have developed techniques to effectively tune the connectivity of sparsely-connected artificial neural networks, which have the potential to be more computationally efficient than their fully-connected counterparts and more closely resemble the architectures of biological systems. We here present a normalisation, based on the biophysical behaviour of neuronal dendrites receiving distributed synaptic inputs, that divides the weight of an artificial neuron's afferent contacts by their number. We apply this dendritic normalisation to various sparsely-connected feedforward network architectures, as well as simple recurrent and self-organised networks with spatially extended units. The learning performance is significantly increased, providing an improvement over other widely-used normalisations in sparse networks. The results are two-fold, being both a practical advance in machine learning and an insight into how the structure of neuronal dendritic arbours may contribute to computation.
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Affiliation(s)
- Alex D. Bird
- Ernst Strüngmann Institute for Neuroscience (ESI) in co-operation with Max Planck Society, Frankfurt, Germany
- Frankfurt Institute for Advanced Studies (FIAS), Frankfurt, Germany
- ICAR3R-Interdisciplinary Centre for 3Rs in Animal Research, Faculty of Medicine, Justus Liebig University Giessen, Giessen, Germany
| | - Peter Jedlicka
- Frankfurt Institute for Advanced Studies (FIAS), Frankfurt, Germany
- ICAR3R-Interdisciplinary Centre for 3Rs in Animal Research, Faculty of Medicine, Justus Liebig University Giessen, Giessen, Germany
| | - Hermann Cuntz
- Ernst Strüngmann Institute for Neuroscience (ESI) in co-operation with Max Planck Society, Frankfurt, Germany
- Frankfurt Institute for Advanced Studies (FIAS), Frankfurt, Germany
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18
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Formation and integration of new neurons in the adult hippocampus. Nat Rev Neurosci 2021; 22:223-236. [PMID: 33633402 DOI: 10.1038/s41583-021-00433-z] [Citation(s) in RCA: 131] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2021] [Indexed: 01/31/2023]
Abstract
Neural stem cells (NSCs) generate new neurons throughout life in the mammalian brain. Adult-born neurons shape brain function, and endogenous NSCs could potentially be harnessed for brain repair. In this Review, focused on hippocampal neurogenesis in rodents, we highlight recent advances in the field based on novel technologies (including single-cell RNA sequencing, intravital imaging and functional observation of newborn cells in behaving mice) and characterize the distinct developmental steps from stem cell activation to the integration of newborn neurons into pre-existing circuits. Further, we review current knowledge of how levels of neurogenesis are regulated, discuss findings regarding survival and maturation of adult-born cells and describe how newborn neurons affect brain function. The evidence arguing for (and against) lifelong neurogenesis in the human hippocampus is briefly summarized. Finally, we provide an outlook of what is needed to improve our understanding of the mechanisms and functional consequences of adult neurogenesis and how the field may move towards more translational relevance in the context of acute and chronic neural injury and stem cell-based brain repair.
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19
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Huckleberry KA, Shansky RM. The unique plasticity of hippocampal adult-born neurons: Contributing to a heterogeneous dentate. Hippocampus 2021; 31:543-556. [PMID: 33638581 DOI: 10.1002/hipo.23318] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/15/2021] [Accepted: 02/09/2021] [Indexed: 12/14/2022]
Abstract
The dentate gyrus (DG) of the hippocampus is evolutionarily conserved as one of the few sites of adult neurogenesis in mammals. Although there is clear evidence that neurogenesis is necessary for healthy hippocampal function, whether adult-born neurons are simply integrated into existing hippocampal networks to serve a similar purpose to that of developmentally born neurons or whether they represent a discrete cell population with unique functions remains less clear. In this review, we consider evidence for discrete cellular, synaptic, and structural features of adult-born DG neurons, suggesting that neurogenesis contributes to the formation of a heterogeneous DG. We therefore propose that hippocampal neurogenesis creates a specialized neuronal subpopulation that may play a key role in hippocampal functions like episodic memory. We note critical gaps in this extensive body of work, including a general failure to include female animals in relevant research and a need for more precise consideration of intrahippocampal neuroanatomy.
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Affiliation(s)
- Kylie A Huckleberry
- Behavioral Neuroscience Program, Department of Psychology, Northeastern University, Boston, Massachusetts, USA
| | - Rebecca M Shansky
- Behavioral Neuroscience Program, Department of Psychology, Northeastern University, Boston, Massachusetts, USA
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20
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Hildebrandt-Einfeldt L, Yap K, Paul MH, Stoffer C, Zahn N, Drakew A, Lenz M, Vlachos A, Deller T. Crossed Entorhino-Dentate Projections Form and Terminate With Correct Layer-Specificity in Organotypic Slice Cultures of the Mouse Hippocampus. Front Neuroanat 2021; 15:637036. [PMID: 33643001 PMCID: PMC7904698 DOI: 10.3389/fnana.2021.637036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/12/2021] [Indexed: 11/13/2022] Open
Abstract
The entorhino-dentate projection, i.e., the perforant pathway, terminates in a highly ordered and laminated fashion in the rodent dentate gyrus (DG): fibers arising from the medial entorhinal cortex (MEC) terminate in the middle molecular layer, whereas fibers arising from the lateral entorhinal cortex (LEC) terminate in the outer molecular layer of the DG. In rats and rabbits, a crossed entorhino-dentate projection exists, which originates from the entorhinal cortex (EC) and terminates in the contralateral DG. In contrast, in mice, such a crossed projection is reportedly absent. Using single and double mouse organotypic entorhino-hippocampal slice cultures, we studied the ipsi- and crossed entorhino-dentate projections. Viral tracing revealed that entorhino-dentate projections terminate with a high degree of lamina-specificity in single as well as in double cultures. Furthermore, in double cultures, entorhinal axons arising from one slice freely intermingled with entorhinal axons originating from the other slice. In single as well as in double cultures, entorhinal axons exhibited a correct topographical projection to the DG: medial entorhinal axons terminated in the middle and lateral entorhinal axons terminated in the outer molecular layer. Finally, entorhinal neurons were virally transduced with Channelrhodopsin2-YFP and stimulated with light, revealing functional connections between the EC and dentate granule cells. We conclude from our findings that entorhino-dentate projections form bilaterally in the mouse hippocampus in vitro and that the mouse DG provides a permissive environment for crossed entorhinal fibers.
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Affiliation(s)
- Lars Hildebrandt-Einfeldt
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Kenrick Yap
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Mandy H Paul
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Carolin Stoffer
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Nadine Zahn
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Alexander Drakew
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Maximilian Lenz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Center Brain Links Brain Tools, University of Freiburg, Freiburg, Germany.,Center for Basics in Neuro Modulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
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21
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Structural and Functional Synaptic Plasticity Induced by Convergent Synapse Loss in the Drosophila Neuromuscular Circuit. J Neurosci 2021; 41:1401-1417. [PMID: 33402422 DOI: 10.1523/jneurosci.1492-20.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/28/2020] [Accepted: 12/17/2020] [Indexed: 12/22/2022] Open
Abstract
Throughout the nervous system, the convergence of two or more presynaptic inputs on a target cell is commonly observed. The question we ask here is to what extent converging inputs influence each other's structural and functional synaptic plasticity. In complex circuits, isolating individual inputs is difficult because postsynaptic cells can receive thousands of inputs. An ideal model to address this question is the Drosophila larval neuromuscular junction (NMJ) where each postsynaptic muscle cell receives inputs from two glutamatergic types of motor neurons (MNs), known as 1b and 1s MNs. Notably, each muscle is unique and receives input from a different combination of 1b and 1s MNs; we surveyed multiple muscles for this reason. Here, we identified a cell-specific promoter that allows ablation of 1s MNs postinnervation and measured structural and functional responses of convergent 1b NMJs using microscopy and electrophysiology. For all muscles examined in both sexes, ablation of 1s MNs resulted in NMJ expansion and increased spontaneous neurotransmitter release at corresponding 1b NMJs. This demonstrates that 1b NMJs can compensate for the loss of convergent 1s MNs. However, only a subset of 1b NMJs showed compensatory evoked neurotransmission, suggesting target-specific plasticity. Silencing 1s MNs led to similar plasticity at 1b NMJs, suggesting that evoked neurotransmission from 1s MNs contributes to 1b synaptic plasticity. Finally, we genetically blocked 1s innervation in male larvae and robust 1b synaptic plasticity was eliminated, raising the possibility that 1s NMJ formation is required to set up a reference for subsequent synaptic perturbations.SIGNIFICANCE STATEMENT In complex neural circuits, multiple convergent inputs contribute to the activity of the target cell, but whether synaptic plasticity exists among these inputs has not been thoroughly explored. In this study, we examined synaptic plasticity in the structurally and functionally tractable Drosophila larval neuromuscular system. In this convergent circuit, each muscle is innervated by a unique pair of motor neurons. Removal of one neuron after innervation causes the adjacent neuron to increase neuromuscular junction outgrowth and functional output. However, this is not a general feature as each motor neuron differentially compensates. Further, robust compensation requires initial coinnervation by both neurons. Understanding how neurons respond to perturbations in adjacent neurons will provide insight into nervous system plasticity in both healthy and disease states.
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22
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Gustus K, Li L, Newville J, Cunningham LA. Functional and Structural Correlates of Impaired Enrichment-Mediated Adult Hippocampal Neurogenesis in a Mouse Model of Prenatal Alcohol Exposure. Brain Plast 2020; 6:67-82. [PMID: 33680847 PMCID: PMC7902980 DOI: 10.3233/bpl-200112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background: Fetal alcohol spectrum disorders (FASDs) are associated with a wide range of cognitive deficiencies. Objective: We previously
found that gestational exposure to moderate levels of alcohol in mice throughout the 1st-2nd human trimester-equivalents
for brain development results in profound impairment of the hippocampal neurogenic response to enriched environment
(EE) in adulthood, without altering baseline neurogenesis rate under standard housing (SH). However, the functional and
structural consequences of impaired EE-mediated neurogenesis in the context of prenatal alcohol exposure (PAE) have
not been determined. Results: Here, we demonstrate that PAE-EE mice display impaired performance on a neurogenesis-dependent
pattern discrimination task, broadened behavioral activation of the dentate gyrus, as assessed by expression of the immediate
early gene, c-Fos, and impaired dendritic branching of adult-generated dentate granule cells (aDGCs). Conclusions: These studies further underscore the impact of moderate gestational alcohol exposure on adult hippocampal plasticity and support adult hippocampal neurogenesis as a potential therapeutic target to remediate certain neurological outcomes in FASD.
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Affiliation(s)
- Kymberly Gustus
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Lu Li
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Jessie Newville
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Lee Anna Cunningham
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
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23
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Chater TE, Goda Y. My Neighbour Hetero-deconstructing the mechanisms underlying heterosynaptic plasticity. Curr Opin Neurobiol 2020; 67:106-114. [PMID: 33160201 DOI: 10.1016/j.conb.2020.10.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/05/2020] [Accepted: 10/11/2020] [Indexed: 02/06/2023]
Abstract
Synapses change in strength following patterns of activity, but in many cases seemingly inactive neighbouring synapses also undergo changes in strength. These heterosynaptic changes occur across developmental time-points in various brain circuits in different species, but their precise molecular mechanisms are not well understood. Additionally, heterosynaptic changes can mirror homosynaptic plasticity or occur in opposition to homosynaptic changes. In this review we consider what useful functionality heterosynaptic dynamics could potentially endow the circuit with, and the underlying signalling events that implement heterosynaptic changes. We discuss what unanswered questions remain, and what the future looks like for understanding the logic of synaptic plasticity.
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Affiliation(s)
- Thomas E Chater
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Yukiko Goda
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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Ebner C, Clopath C, Jedlicka P, Cuntz H. Unifying Long-Term Plasticity Rules for Excitatory Synapses by Modeling Dendrites of Cortical Pyramidal Neurons. Cell Rep 2020; 29:4295-4307.e6. [PMID: 31875541 PMCID: PMC6941234 DOI: 10.1016/j.celrep.2019.11.068] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 05/02/2019] [Accepted: 11/15/2019] [Indexed: 11/30/2022] Open
Abstract
A large number of experiments have indicated that precise spike times, firing rates, and synapse locations crucially determine the dynamics of long-term plasticity induction in excitatory synapses. However, it remains unknown how plasticity mechanisms of synapses distributed along dendritic trees cooperate to produce the wide spectrum of outcomes for various plasticity protocols. Here, we propose a four-pathway plasticity framework that is well grounded in experimental evidence and apply it to a biophysically realistic cortical pyramidal neuron model. We show in computer simulations that several seemingly contradictory experimental landmark studies are consistent with one unifying set of mechanisms when considering the effects of signal propagation in dendritic trees with respect to synapse location. Our model identifies specific spatiotemporal contributions of dendritic and axo-somatic spikes as well as of subthreshold activation of synaptic clusters, providing a unified parsimonious explanation not only for rate and timing dependence but also for location dependence of synaptic changes. A phenomenological synaptic plasticity rule is applied to a pyramidal neuron model Model reproduces rate-, timing-, and location-dependent plasticity results Active dendrites allow plasticity via dendritic spikes and subthreshold events Cooperative plasticity exists across the dendritic tree and within single branches
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Affiliation(s)
- Christian Ebner
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany; Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, 60528 Frankfurt am Main, Germany; NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; Institute for Biology, Humboldt-Universität zu Berlin, 10117 Berlin, Germany.
| | - Claudia Clopath
- Computational Neuroscience Laboratory, Bioengineering Department, Imperial College London, London SW7 2AZ, UK
| | - Peter Jedlicka
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany; Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60528 Frankfurt am Main, Germany; ICAR3R-Interdisciplinary Centre for 3Rs in Animal Research, Faculty of Medicine, Justus-Liebig-University, 35392 Giessen, Germany
| | - Hermann Cuntz
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany; Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, 60528 Frankfurt am Main, Germany
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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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Adult-Born Hippocampal Neurons Undergo Extended Development and Are Morphologically Distinct from Neonatally-Born Neurons. J Neurosci 2020; 40:5740-5756. [PMID: 32571837 DOI: 10.1523/jneurosci.1665-19.2020] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 02/28/2020] [Accepted: 05/04/2020] [Indexed: 11/21/2022] Open
Abstract
During immature stages, adult-born neurons pass through critical periods for survival and plasticity. It is generally assumed that by 2 months of age adult-born neurons are mature and equivalent to the broader neuronal population, raising questions of how they might contribute to hippocampal function in old age when neurogenesis has declined. However, few have examined adult-born neurons beyond the critical period or directly compared them to neurons born in infancy. Here, we used a retrovirus to visualize functionally relevant morphological features of 2- to 24-week-old adult-born neurons in male rats. From 2 to 7 weeks, neurons grew and attained a relatively mature phenotype. However, several features of 7-week-old neurons suggested a later wave of growth: these neurons had larger nuclei, thicker dendrites, and more dendritic filopodia than all other groups. Indeed, between 7 and 24 weeks, adult-born neurons gained additional dendritic branches, formed a second primary dendrite, acquired more mushroom spines, and had enlarged mossy fiber presynaptic terminals. Compared with neonatal-born neurons, old adult-born neurons had greater spine density, larger presynaptic terminals, and more putative efferent filopodial contacts onto inhibitory neurons. By integrating rates of cell birth and growth across the life span, we estimate that adult neurogenesis ultimately produces half of the cells and the majority of spines in the dentate gyrus. Critically, protracted development contributes to the plasticity of the hippocampus through to the end of life, even after cell production declines. Persistent differences from neonatal-born neurons may additionally endow adult-born neurons with unique functions even after they have matured.SIGNIFICANCE STATEMENT Neurogenesis occurs in the hippocampus throughout adult life and contributes to memory and emotion. It is generally assumed that new neurons have the greatest impact on behavior when they are immature and plastic. However, since neurogenesis declines dramatically with age, it is unclear how they might contribute to behavior later in life when cell proliferation has slowed. Here we find that newborn neurons mature over many months in rats and may end up with distinct morphological features compared with neurons born in infancy. Using a mathematical model, we estimate that a large fraction of neurons is added in adulthood. Moreover, their extended growth produces a reserve of plasticity that persists even after neurogenesis has declined to low rates.
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27
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Rathour RK, Narayanan R. Degeneracy in hippocampal physiology and plasticity. Hippocampus 2019; 29:980-1022. [PMID: 31301166 PMCID: PMC6771840 DOI: 10.1002/hipo.23139] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 05/27/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022]
Abstract
Degeneracy, defined as the ability of structurally disparate elements to perform analogous function, has largely been assessed from the perspective of maintaining robustness of physiology or plasticity. How does the framework of degeneracy assimilate into an encoding system where the ability to change is an essential ingredient for storing new incoming information? Could degeneracy maintain the balance between the apparently contradictory goals of the need to change for encoding and the need to resist change towards maintaining homeostasis? In this review, we explore these fundamental questions with the mammalian hippocampus as an example encoding system. We systematically catalog lines of evidence, spanning multiple scales of analysis that point to the expression of degeneracy in hippocampal physiology and plasticity. We assess the potential of degeneracy as a framework to achieve the conjoint goals of encoding and homeostasis without cross-interferences. We postulate that biological complexity, involving interactions among the numerous parameters spanning different scales of analysis, could establish disparate routes towards accomplishing these conjoint goals. These disparate routes then provide several degrees of freedom to the encoding-homeostasis system in accomplishing its tasks in an input- and state-dependent manner. Finally, the expression of degeneracy spanning multiple scales offers an ideal reconciliation to several outstanding controversies, through the recognition that the seemingly contradictory disparate observations are merely alternate routes that the system might recruit towards accomplishment of its goals.
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Affiliation(s)
- Rahul K. Rathour
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
| | - Rishikesh Narayanan
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
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28
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Quinn DP, Kolar A, Harris SA, Wigerius M, Fawcett JP, Krueger SR. The Stability of Glutamatergic Synapses Is Independent of Activity Level, but Predicted by Synapse Size. Front Cell Neurosci 2019; 13:291. [PMID: 31316356 PMCID: PMC6609312 DOI: 10.3389/fncel.2019.00291] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 06/14/2019] [Indexed: 01/23/2023] Open
Abstract
Neuronal activity is thought to drive the remodeling of circuits in the mammalian cerebral cortex. However, its precise function in the underlying formation and elimination of glutamatergic synapses has remained controversial. To clarify the role of activity in synapse turnover, we have assessed the effects of inhibition of glutamate release from a sparse subset of cultured hippocampal neurons on synapse turnover. Sustained chemogenetic attenuation of release through presynaptic expression of a designer receptor exclusively activated by designer drugs (DREADD) had no effect on the formation or elimination of glutamatergic synapses. Sparse expression of tetanus neurotoxin light chain (TeNT-LC), a synaptobrevin-cleaving protease that completely abolishes neurotransmitter release, likewise did not lead to changes in the rate of synapse elimination, although it reduced the rate of synapse formation. The stability of active and silenced synapses correlated with measures of synapse size. While not excluding a modulatory role in synapse elimination, our findings show that synaptic activity is neither required for the removal nor the maintenance of glutamatergic synapses between hippocampal neurons. Our results also demonstrate that the stability of glutamatergic synapses scales with their size irrespective of their activity.
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Affiliation(s)
- Dylan P Quinn
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada.,Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Annette Kolar
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Sydney A Harris
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Michael Wigerius
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - James P Fawcett
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Stefan R Krueger
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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29
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Mishra P, Narayanan R. Disparate forms of heterogeneities and interactions among them drive channel decorrelation in the dentate gyrus: Degeneracy and dominance. Hippocampus 2019; 29:378-403. [PMID: 30260063 PMCID: PMC6420062 DOI: 10.1002/hipo.23035] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 09/05/2018] [Accepted: 09/20/2018] [Indexed: 12/29/2022]
Abstract
The ability of a neuronal population to effectuate channel decorrelation, which is one form of response decorrelation, has been identified as an essential prelude to efficient neural encoding. To what extent are diverse forms of local and afferent heterogeneities essential in accomplishing channel decorrelation in the dentate gyrus (DG)? Here, we incrementally incorporated four distinct forms of biological heterogeneities into conductance-based network models of the DG and systematically delineate their relative contributions to channel decorrelation. First, to effectively incorporate intrinsic heterogeneities, we built physiologically validated heterogeneous populations of granule (GC) and basket cells (BC) through independent stochastic search algorithms spanning exhaustive parametric spaces. These stochastic search algorithms, which were independently constrained by experimentally determined ion channels and by neurophysiological signatures, revealed cellular-scale degeneracy in the DG. Specifically, in GC and BC populations, disparate parametric combinations yielded similar physiological signatures, with underlying parameters exhibiting significant variability and weak pair-wise correlations. Second, we introduced synaptic heterogeneities through randomization of local synaptic strengths. Third, in including adult neurogenesis, we subjected the valid model populations to randomized structural plasticity and matched neuronal excitability to electrophysiological data. We assessed networks comprising different combinations of these three local heterogeneities with identical or heterogeneous afferent inputs from the entorhinal cortex. We found that the three forms of local heterogeneities were independently and synergistically capable of mediating significant channel decorrelation when the network was driven by identical afferent inputs. However, when we incorporated afferent heterogeneities into the network to account for the divergence in DG afferent connectivity, the impact of all three forms of local heterogeneities was significantly suppressed by the dominant role of afferent heterogeneities in mediating channel decorrelation. Our results unveil a unique convergence of cellular- and network-scale degeneracy in the emergence of channel decorrelation in the DG, whereby disparate forms of local and afferent heterogeneities could synergistically drive input discriminability.
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Affiliation(s)
- Poonam Mishra
- Cellular Neurophysiology Laboratory, Molecular Biophysics UnitIndian Institute of ScienceBangaloreIndia
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics UnitIndian Institute of ScienceBangaloreIndia
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30
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Augusto-Oliveira M, Arrifano GPF, Malva JO, Crespo-Lopez ME. Adult Hippocampal Neurogenesis in Different Taxonomic Groups: Possible Functional Similarities and Striking Controversies. Cells 2019; 8:cells8020125. [PMID: 30764477 PMCID: PMC6406791 DOI: 10.3390/cells8020125] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 12/13/2022] Open
Abstract
Adult neurogenesis occurs in many species, from fish to mammals, with an apparent reduction in the number of both neurogenic zones and new neurons inserted into established circuits with increasing brain complexity. Although the absolute number of new neurons is high in some species, the ratio of these cells to those already existing in the circuit is low. Continuous replacement/addition plays a role in spatial navigation (migration) and other cognitive processes in birds and rodents, but none of the literature relates adult neurogenesis to spatial navigation and memory in primates and humans. Some models developed by computational neuroscience attribute a high weight to hippocampal adult neurogenesis in learning and memory processes, with greater relevance to pattern separation. In contrast to theories involving neurogenesis in cognitive processes, absence/rarity of neurogenesis in the hippocampus of primates and adult humans was recently suggested and is under intense debate. Although the learning process is supported by plasticity, the retention of memories requires a certain degree of consolidated circuitry structures, otherwise the consolidation process would be hampered. Here, we compare and discuss hippocampal adult neurogenesis in different species and the inherent paradoxical aspects.
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Affiliation(s)
- Marcus Augusto-Oliveira
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil.
- Laboratory of Research on Neurodegeneration and Infection, University Hospital João de Barros Barreto, Federal University of Pará, Belém 66073-005, Brazil.
- Laboratory of Experimental Neuropathology, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
| | - Gabriela P F Arrifano
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil.
- Laboratory of Experimental Neuropathology, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
| | - João O Malva
- Coimbra Institute for Clinical and Biomedical Research (iCBR), and Center for Neuroscience and Cell Biology and Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, Coimbra 3000-548, Portugal.
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil.
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31
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Balta EA, Schäffner I, Wittmann MT, Sock E, von Zweydorf F, von Wittgenstein J, Steib K, Heim B, Kremmer E, Häberle BM, Ueffing M, Lie DC, Gloeckner CJ. Phosphorylation of the neurogenic transcription factor SOX11 on serine 133 modulates neuronal morphogenesis. Sci Rep 2018; 8:16196. [PMID: 30385877 PMCID: PMC6212486 DOI: 10.1038/s41598-018-34480-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/25/2018] [Indexed: 02/07/2023] Open
Abstract
The intellectual disability gene, Sox11, encodes for a critical neurodevelopmental transcription factor with functions in precursor survival, neuronal fate determination, migration and morphogenesis. The mechanisms regulating SOX11’s activity remain largely unknown. Mass spectrometric analysis uncovered that SOX11 can be post-translationally modified by phosphorylation. Here, we report that phosphorylatable serines surrounding the high-mobility group box modulate SOX11’s transcriptional activity. Through Mass Spectrometry (MS), co-immunoprecipitation assays and in vitro phosphorylation assays followed by MS we verified that protein kinase A (PKA) interacts with SOX11 and phosphorylates it on S133. In vivo replacement of SoxC factors in developing adult-generated hippocampal neurons with SOX11 S133 phospho-mutants indicated that phosphorylation on S133 modulates dendrite development of adult-born dentate granule neurons, while reporter assays suggested that S133 phosphorylation fine-tunes the activation of select target genes. These data provide novel insight into the control of the critical neurodevelopmental regulator SOX11 and imply SOX11 as a mediator of PKA-regulated neuronal development.
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Affiliation(s)
- Elli-Anna Balta
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Iris Schäffner
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Marie-Theres Wittmann
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Elisabeth Sock
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Felix von Zweydorf
- DZNE-German Center for Neurodegenerative Diseases, 72076, Tübingen, Germany
| | - Julia von Wittgenstein
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Kathrin Steib
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764, Neuherberg, Germany
| | - Birgit Heim
- University of Tübingen, Institute for Ophthalmic Research, Center for Ophthalmology, 72076, Tübingen, Germany
| | - Elisabeth Kremmer
- Monoclonal Antibody Core Facility, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764, Neuherberg, Germany
| | - Benjamin Martin Häberle
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Marius Ueffing
- University of Tübingen, Institute for Ophthalmic Research, Center for Ophthalmology, 72076, Tübingen, Germany
| | - Dieter Chichung Lie
- Institute of Biochemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054, Erlangen, Germany.
| | - Christian Johannes Gloeckner
- DZNE-German Center for Neurodegenerative Diseases, 72076, Tübingen, Germany. .,University of Tübingen, Institute for Ophthalmic Research, Center for Ophthalmology, 72076, Tübingen, Germany.
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