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Onimus O, Arrivet F, Souza INDO, Bertrand B, Castel J, Luquet S, Mothet JP, Heck N, Gangarossa G. The gut-brain vagal axis scales hippocampal memory processes and plasticity. Neurobiol Dis 2024; 199:106569. [PMID: 38885849 DOI: 10.1016/j.nbd.2024.106569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 06/05/2024] [Accepted: 06/13/2024] [Indexed: 06/20/2024] Open
Abstract
The vagus nerve serves as an interoceptive relay between the body and the brain. Despite its well-established role in feeding behaviors, energy metabolism, and cognitive functions, the intricate functional processes linking the vagus nerve to the hippocampus and its contribution to learning and memory dynamics remain still elusive. Here, we investigated whether and how the gut-brain vagal axis contributes to hippocampal learning and memory processes at behavioral, functional, cellular, and molecular levels. Our results indicate that the integrity of the vagal axis is essential for long-term recognition memories, while sparing other forms of memory. In addition, by combing multi-scale approaches, our findings show that the gut-brain vagal tone exerts a permissive role in scaling intracellular signaling events, gene expressions, hippocampal dendritic spines density as well as functional long-term plasticities (LTD and LTP). These results highlight the critical role of the gut-brain vagal axis in maintaining the spontaneous and homeostatic functions of hippocampal ensembles and in regulating their learning and memory functions. In conclusion, our study provides comprehensive insights into the multifaceted involvement of the gut-brain vagal axis in shaping time-dependent hippocampal learning and memory dynamics. Understanding the mechanisms underlying this interoceptive body-brain neuronal communication may pave the way for novel therapeutic approaches in conditions associated with cognitive decline, including neurodegenerative disorders.
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Affiliation(s)
- Oriane Onimus
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | - Faustine Arrivet
- Sorbonne Université, CNRS, INSERM, Neurosciences Paris Seine, Institut de Biologie Paris Seine, F-75005 Paris, France
| | - Isis Nem de Oliveira Souza
- Biophotonics and Synapse Physiopathology Team, Laboratoire LuMIn UMR9024 Université Paris-Saclay, ENS Paris-Saclay, CNRS, CentraleSupelec, 91190 Gif-sur-Yvette, France; Laboratory of Molecular Pharmacology, Institute of Biomedical Sciences, Universidade Federal do Rio de Janeiro, Brazil
| | - Benoit Bertrand
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | - Julien Castel
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | - Serge Luquet
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | - Jean-Pierre Mothet
- Biophotonics and Synapse Physiopathology Team, Laboratoire LuMIn UMR9024 Université Paris-Saclay, ENS Paris-Saclay, CNRS, CentraleSupelec, 91190 Gif-sur-Yvette, France
| | - Nicolas Heck
- Sorbonne Université, CNRS, INSERM, Neurosciences Paris Seine, Institut de Biologie Paris Seine, F-75005 Paris, France
| | - Giuseppe Gangarossa
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France; Institut Universitaire de France, France.
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2
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Harris KM, Kuwajima M, Flores JC, Zito K. Synapse-specific structural plasticity that protects and refines local circuits during LTP and LTD. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230224. [PMID: 38853547 DOI: 10.1098/rstb.2023.0224] [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: 10/17/2023] [Accepted: 01/05/2024] [Indexed: 06/11/2024] Open
Abstract
Synapses form trillions of connections in the brain. Long-term potentiation (LTP) and long-term depression (LTD) are cellular mechanisms vital for learning that modify the strength and structure of synapses. Three-dimensional reconstruction from serial section electron microscopy reveals three distinct pre- to post-synaptic arrangements: strong active zones (AZs) with tightly docked vesicles, weak AZs with loose or non-docked vesicles, and nascent zones (NZs) with a postsynaptic density but no presynaptic vesicles. Importantly, LTP can be temporarily saturated preventing further increases in synaptic strength. At the onset of LTP, vesicles are recruited to NZs, converting them to AZs. During recovery of LTP from saturation (1-4 h), new NZs form, especially on spines where AZs are most enlarged by LTP. Sentinel spines contain smooth endoplasmic reticulum (SER), have the largest synapses and form clusters with smaller spines lacking SER after LTP recovers. We propose a model whereby NZ plasticity provides synapse-specific AZ expansion during LTP and loss of weak AZs that drive synapse shrinkage during LTD. Spine clusters become functionally engaged during LTP or disassembled during LTD. Saturation of LTP or LTD probably acts to protect recently formed memories from ongoing plasticity and may account for the advantage of spaced over massed learning. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Kristen M Harris
- Department of Neuroscience and Center for Learning and Memory, The University of Texas at Austin , Austin, TX 78712, USA
| | - Masaaki Kuwajima
- Department of Neuroscience and Center for Learning and Memory, The University of Texas at Austin , Austin, TX 78712, USA
| | - Juan C Flores
- Center for Neuroscience, University of California , Davis, CA 95618, USA
| | - Karen Zito
- Center for Neuroscience, University of California , Davis, CA 95618, USA
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3
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Hedrick NG, Wright WJ, Komiyama T. Local and global predictors of synapse elimination during motor learning. SCIENCE ADVANCES 2024; 10:eadk0540. [PMID: 38489360 PMCID: PMC10942101 DOI: 10.1126/sciadv.adk0540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 02/12/2024] [Indexed: 03/17/2024]
Abstract
During learning, synaptic connections between excitatory neurons in the brain display considerable dynamism, with new connections being added and old connections eliminated. Synapse elimination offers an opportunity to understand the features of synapses that the brain deems dispensable. However, with limited observations of synaptic activity and plasticity in vivo, the features of synapses subjected to elimination remain poorly understood. Here, we examined the functional basis of synapse elimination in the apical dendrites of L2/3 neurons in the primary motor cortex throughout motor learning. We found no evidence that synapse elimination is facilitated by a lack of activity or other local forms of plasticity. Instead, eliminated synapses display asynchronous activity with nearby synapses, suggesting that functional synaptic clustering is a critical component of synapse survival. In addition, eliminated synapses show delayed activity timing with respect to postsynaptic output. Thus, synaptic inputs that fail to be co-active with their neighboring synapses or are mistimed with neuronal output are targeted for elimination.
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Affiliation(s)
- Nathan G. Hedrick
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
- Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA, USA
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
- Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA, USA
| | - William J. Wright
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
- Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA, USA
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
- Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA, USA
| | - Takaki Komiyama
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
- Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA, USA
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
- Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA, USA
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4
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Prengel TM, Brunne B, Habiballa M, Rune GM. Sexually differentiated microglia and CA1 hippocampal synaptic connectivity. J Neuroendocrinol 2023; 35:e13276. [PMID: 37170708 DOI: 10.1111/jne.13276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/14/2023] [Accepted: 03/31/2023] [Indexed: 05/13/2023]
Abstract
Microglia have been shown to sculpt postnatal circuitry from birth up to adulthood due to their role in both synapse formation, synaptic pruning, and the elimination of weak, redundant synapses. Microglia are differentiated in a sex-dependent manner. In this study, we tested whether sexual differentiation of microglia results in sex-dependent postnatal reorganization of CA1 synaptic connectivity in the hippocampus. The stereological counting of synapses in mice using electron microscopy showed a continuous rise in synapse density until the fourth week, followed by a plateau phase and loss of synapses from the eighth week onwards, with no difference between sexes. This course of alteration in synapse numbers did not differ between sexes. However, selectively, on postnatal day (P) 14 the density of synapses was significantly higher in the female than in the male hippocampus. Higher synapse density in females was paralleled by higher activity of microglia, as indicated by morphological changes, CD68 expression, and proximity of microglia to synaptic sites. In Thy1-GFP mice, consistent with increased synapse numbers, bouton density was also clearly increased in females at P14. At this time point, CD47 expression, the "don't eat me" signal of neurons, was similar in males and females. The decrease in bouton density thereafter in conjunction with increased synapse numbers argues for a role of microglia in the formation of multispine boutons (MSB). Our data in females at P14 support the regulatory role of microglia in synapse density. Sexual differentiation of microglia, however, does not substantially affect long-term synaptic reorganization in the hippocampus.
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Affiliation(s)
- Tim M Prengel
- Institute of Neuroanatomy, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Bianka Brunne
- Institute of Neuroanatomy, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Moataz Habiballa
- Institute of Neuroanatomy, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Gabriele M Rune
- Institute of Cell Biology and Neurobiology, Charité Universitätsmedizin Berlin, Berlin, Germany
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5
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Alpha7 nicotinic acetylcholine receptor agonist PHA-543613 improves memory deficits in presenilin 1 and presenilin 2 conditional double knockout mice. Exp Neurol 2023; 359:114271. [PMID: 36370840 DOI: 10.1016/j.expneurol.2022.114271] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/18/2022] [Accepted: 11/06/2022] [Indexed: 11/11/2022]
Abstract
Cholinergic system dysfunction has been considered as a critical feature of neurodegenerative progression in Alzheimer's disease (AD). The α7 nicotinic acetylcholine receptors (α7-nAChRs) are widely expressed in the hippocampus cortex and play an important role in memory formation, considered as potential therapeutic agents targets. However, underlying mechanisms have not been fully elucidated. Here, we combine behavioral, molecular biological methods with in vitro slice and in vivo multichannel electrophysiological recording techniques to investigate the molecular, cellular synaptic and neuronal mechanisms of activating α7-nAChR by PHA-543613 (a selective α7-nAChR agonist), which influences the impaired cognitive function using presenilin 1 (PS1) and presenilin 2 (PS2) conditional double knockout (cDKO) mice. Our results demonstrated that PHA-543613 treatment significantly improved the impaired hippocampus-related memory via recovering the reduced the hippocampal synaptic protein levels of α7-nAChR, NMADAR and AMPAR, thereby restoring the impaired post-tetanic potentiation (PTP), long-term potentiation (LTP), activation of molecular signaling pathway for neuronal protection, theta power and strength of theta-gamma phase-amplitude coupling (PAC) at hippocampus in 6-month-old cDKO mice. For the first time, we systematically reveal the mechanisms by which PHA-543613 improves memory deficits at different levels. Therefore, our findings may be significant for the development of therapeutic strategies for AD.
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6
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Kim YK, Jung YS, Song J. Transcriptome Profile in the Mouse Brain of Hepatic Encephalopathy and Alzheimer's Disease. Int J Mol Sci 2022; 24:ijms24010675. [PMID: 36614117 PMCID: PMC9821016 DOI: 10.3390/ijms24010675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/13/2022] [Accepted: 12/18/2022] [Indexed: 01/03/2023] Open
Abstract
Hepatic encephalopathy (HE) is a chronic metabolic disease accompanied by neuropathological and neuropsychiatric features, including memory deficits, psychomotor dysfunction, depression, and anxiety. Alzheimer's disease (AD), the most common neurodegenerative disease, is characterized by tau hyperphosphorylation, excessive amyloid beta (Aβ) accumulation, the formation of fibrillary tangles, hippocampus atrophy, and neuroinflammation. Recent studies have suggested a positive correlation between HE and AD. Some studies reported that an impaired cholesterol pathway, abnormal bile acid secretion, excessive ammonia level, impaired Aβ clearance, astrocytic dysfunction, and abnormal γ-aminobutyric acid GABAergic neuronal signaling in HE may also be involved in AD pathology. However, the mechanisms and related genes involved in AD-like pathology in the HE brain are unclear. Thus, we compared the cortical transcriptome profile between an HE mouse model, bile duct ligation (BDL), and an AD mouse model, the 5×FAD. Our study showed that the expression of many genes implicated in HE is associated with neuronal dysfunction in AD mice. We found changes in various protein-coding RNAs, implicated in synapses, neurogenesis, neuron projection, neuron differentiation, and neurite outgrowth, and non-coding RNAs possibly associated with neuropathology. Our data provide an important resource for further studies to elucidate AD-like pathophysiology in HE patients.
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Affiliation(s)
- Young-Kook Kim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Republic of Korea
| | - Yoon Seok Jung
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Republic of Korea
| | - Juhyun Song
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Republic of Korea
- Correspondence: ; Tel.: +82-61-379-2706; Fax: +82-61-375-5834
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7
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Meng L, Zou L, Xiong M, Chen J, Zhang X, Yu T, Li Y, Liu C, Chen G, Wang Z, Ye K, Zhang Z. A synapsin Ⅰ cleavage fragment contributes to synaptic dysfunction in Alzheimer's disease. Aging Cell 2022; 21:e13619. [PMID: 35443102 PMCID: PMC9124304 DOI: 10.1111/acel.13619] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 02/24/2022] [Accepted: 04/04/2022] [Indexed: 12/02/2022] Open
Abstract
Synaptic dysfunction is a key feature of Alzheimer's disease (AD). However, the molecular mechanisms underlying synaptic dysfunction remain unclear. Here, we show that synapsin Ⅰ, one of the most important synaptic proteins, is fragmented by the cysteine proteinase asparagine endopeptidase (AEP). AEP cleaves synapsin at N82 in the brains of AD patients and generates the C‐terminal synapsin Ⅰ (83–705) fragment. This fragment is abnormally distributed in neurons and induces synaptic dysfunction. Overexpression of AEP in the hippocampus of wild‐type mice results in the production of the synapsin Ⅰ (83–705) fragment and induces synaptic dysfunction and cognitive deficits. Moreover, overexpression of the AEP‐generated synapsin Ⅰ (83–705) fragment in the hippocampus of tau P301S transgenic mice and wild‐type mice promotes synaptic dysfunction and cognitive deficits. These findings suggest a novel mechanism of synaptic dysfunction in AD.
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Affiliation(s)
- Lanxia Meng
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Li Zou
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
- Department of Neurology Zhongnan Hospital of Wuhan University Wuhan China
| | - Min Xiong
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Jiehui Chen
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Xingyu Zhang
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Ting Yu
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Yiming Li
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Congcong Liu
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Guiqin Chen
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
- Department of Pathology and Laboratory Medicine Emory University School of Medicine Atlanta Georgia USA
| | - Zhihao Wang
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine Emory University School of Medicine Atlanta Georgia USA
| | - Zhentao Zhang
- Department of Neurology Renmin Hospital of Wuhan University Wuhan China
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8
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Stacho M, Manahan-Vaughan D. The Intriguing Contribution of Hippocampal Long-Term Depression to Spatial Learning and Long-Term Memory. Front Behav Neurosci 2022; 16:806356. [PMID: 35548697 PMCID: PMC9084281 DOI: 10.3389/fnbeh.2022.806356] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 03/10/2022] [Indexed: 01/03/2023] Open
Abstract
Long-term potentiation (LTP) and long-term depression (LTD) comprise the principal cellular mechanisms that fulfill established criteria for the physiological correlates of learning and memory. Traditionally LTP, that increases synaptic weights, has been ascribed a prominent role in learning and memory whereas LTD, that decreases them, has often been relegated to the category of "counterpart to LTP" that serves to prevent saturation of synapses. In contradiction of these assumptions, studies over the last several years have provided functional evidence for distinct roles of LTD in specific aspects of hippocampus-dependent associative learning and information encoding. Furthermore, evidence of the experience-dependent "pruning" of excitatory synapses, the majority of which are located on dendritic spines, by means of LTD has been provided. In addition, reports exist of the temporal and physical restriction of LTP in dendritic compartments by means of LTD. Here, we discuss the role of LTD and LTP in experience-dependent information encoding based on empirical evidence derived from conjoint behavioral and electrophysiological studies conducted in behaving rodents. We pinpoint the close interrelation between structural modifications of dendritic spines and the occurrence of LTP and LTD. We report on findings that support that whereas LTP serves to acquire the general scheme of a spatial representation, LTD enables retention of content details. We argue that LTD contributes to learning by engaging in a functional interplay with LTP, rather than serving as its simple counterpart, or negator. We propose that similar spatial experiences that share elements of neuronal representations can be modified by means of LTD to enable pattern separation. Therewith, LTD plays a crucial role in the disambiguation of similar spatial representations and the prevention of generalization.
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9
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Wichmann C, Kuner T. Heterogeneity of glutamatergic synapses: cellular mechanisms and network consequences. Physiol Rev 2022; 102:269-318. [PMID: 34727002 DOI: 10.1152/physrev.00039.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chemical synapses are commonly known as a structurally and functionally highly diverse class of cell-cell contacts specialized to mediate communication between neurons. They represent the smallest "computational" unit of the brain and are typically divided into excitatory and inhibitory as well as modulatory categories. These categories are subdivided into diverse types, each representing a different structure-function repertoire that in turn are thought to endow neuronal networks with distinct computational properties. The diversity of structure and function found among a given category of synapses is referred to as heterogeneity. The main building blocks for this heterogeneity are synaptic vesicles, the active zone, the synaptic cleft, the postsynaptic density, and glial processes associated with the synapse. Each of these five structural modules entails a distinct repertoire of functions, and their combination specifies the range of functional heterogeneity at mammalian excitatory synapses, which are the focus of this review. We describe synapse heterogeneity that is manifested on different levels of complexity ranging from the cellular morphology of the pre- and postsynaptic cells toward the expression of different protein isoforms at individual release sites. We attempt to define the range of structural building blocks that are used to vary the basic functional repertoire of excitatory synaptic contacts and discuss sources and general mechanisms of synapse heterogeneity. Finally, we explore the possible impact of synapse heterogeneity on neuronal network function.
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Affiliation(s)
- Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Institute for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg, Germany
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10
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Venkadesh S, Van Horn JD. Integrative Models of Brain Structure and Dynamics: Concepts, Challenges, and Methods. Front Neurosci 2021; 15:752332. [PMID: 34776853 PMCID: PMC8585845 DOI: 10.3389/fnins.2021.752332] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/13/2021] [Indexed: 11/24/2022] Open
Abstract
The anatomical architecture of the brain constrains the dynamics of interactions between various regions. On a microscopic scale, neural plasticity regulates the connections between individual neurons. This microstructural adaptation facilitates coordinated dynamics of populations of neurons (mesoscopic scale) and brain regions (macroscopic scale). However, the mechanisms acting on multiple timescales that govern the reciprocal relationship between neural network structure and its intrinsic dynamics are not well understood. Studies empirically investigating such relationships on the whole-brain level rely on macroscopic measurements of structural and functional connectivity estimated from various neuroimaging modalities such as Diffusion-weighted Magnetic Resonance Imaging (dMRI), Electroencephalography (EEG), Magnetoencephalography (MEG), and functional Magnetic Resonance Imaging (fMRI). dMRI measures the anisotropy of water diffusion along axonal fibers, from which structural connections are estimated. EEG and MEG signals measure electrical activity and magnetic fields induced by the electrical activity, respectively, from various brain regions with a high temporal resolution (but limited spatial coverage), whereas fMRI measures regional activations indirectly via blood oxygen level-dependent (BOLD) signals with a high spatial resolution (but limited temporal resolution). There are several studies in the neuroimaging literature reporting statistical associations between macroscopic structural and functional connectivity. On the other hand, models of large-scale oscillatory dynamics conditioned on network structure (such as the one estimated from dMRI connectivity) provide a platform to probe into the structure-dynamics relationship at the mesoscopic level. Such investigations promise to uncover the theoretical underpinnings of the interplay between network structure and dynamics and could be complementary to the macroscopic level inquiries. In this article, we review theoretical and empirical studies that attempt to elucidate the coupling between brain structure and dynamics. Special attention is given to various clinically relevant dimensions of brain connectivity such as the topological features and neural synchronization, and their applicability for a given modality, spatial or temporal scale of analysis is discussed. Our review provides a summary of the progress made along this line of research and identifies challenges and promising future directions for multi-modal neuroimaging analyses.
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Affiliation(s)
- Siva Venkadesh
- Department of Psychology, University of Virginia, Charlottesville, VA, United States
| | - John Darrell Van Horn
- Department of Psychology, University of Virginia, Charlottesville, VA, United States.,School of Data Science, University of Virginia, Charlottesville, VA, United States
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11
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Soteros BM, Sia GM. Complement and microglia dependent synapse elimination in brain development. WIREs Mech Dis 2021; 14:e1545. [PMID: 34738335 PMCID: PMC9066608 DOI: 10.1002/wsbm.1545] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 10/10/2021] [Accepted: 10/12/2021] [Indexed: 01/31/2023]
Abstract
Synapse elimination, also known as synaptic pruning, is a critical step in the maturation of neural circuits during brain development. Mounting evidence indicates that the complement cascade of the innate immune system plays an important role in synapse elimination. Studies indicate that excess synapses during development are opsonized by complement proteins and subsequently phagocytosed by microglia which expresses complement receptors. The process is regulated by diverse molecular signals, including complement inhibitors that affect the activation of complement, as well as signals that affect microglial recruitment and activation. These signals may promote or inhibit the removal of specific sets of synapses during development. The complement-microglia system has also been implicated in the pathogenesis of several developmental brain disorders, suggesting that the dysregulation of mechanisms of synapse pruning may underlie the specific circuitry defects in these diseases. Here, we review the latest evidence on the molecular and cellular mechanisms of complement-dependent and microglia-dependent synapse elimination during brain development, and highlight the potential of this system as a therapeutic target for developmental brain disorders. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology Neurological Diseases > Stem Cells and Development Immune System Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Breeanne M Soteros
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Gek Ming Sia
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
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12
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Albarran E, Raissi A, Jáidar O, Shatz CJ, Ding JB. Enhancing motor learning by increasing the stability of newly formed dendritic spines in the motor cortex. Neuron 2021; 109:3298-3311.e4. [PMID: 34437845 DOI: 10.1016/j.neuron.2021.07.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 07/10/2021] [Accepted: 07/30/2021] [Indexed: 12/18/2022]
Abstract
Dendritic spine dynamics are thought to be substrates for motor learning and memory, and altered spine dynamics often lead to impaired performance. Here, we describe an exception to this rule by studying mice lacking paired immunoglobulin receptor B (PirB-/-). Pyramidal neuron dendrites in PirB-/- mice have increased spine formation rates and density. Surprisingly, PirB-/- mice learn a skilled reaching task faster than wild-type (WT) littermates. Furthermore, stabilization of learning-induced spines is elevated in PirB-/- mice. Mechanistically, single-spine uncaging experiments suggest that PirB is required for NMDA receptor (NMDAR)-dependent spine shrinkage. The degree of survival of newly formed spines correlates with performance, suggesting that increased spine stability is advantageous for learning. Acute inhibition of PirB function in M1 of adult WT mice increases the survival of learning-induced spines and enhances motor learning. These results demonstrate that there are limits on motor learning that can be lifted by manipulating PirB, even in adulthood.
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Affiliation(s)
- Eddy Albarran
- Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Aram Raissi
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Omar Jáidar
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Carla J Shatz
- Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Neurobiology, Stanford University, Stanford, CA 94305, USA; Stanford Bio-X, Stanford University, Stanford, CA 94305, USA.
| | - Jun B Ding
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA; Stanford Bio-X, Stanford University, Stanford, CA 94305, USA.
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13
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Takeuchi H, Maruyama T, Taki Y, Motoki K, Jeong H, Kotozaki Y, Shinada T, Nakagawa S, Nouchi R, Iizuka K, Yokoyama R, Yamamoto Y, Hanawa S, Araki T, Sakaki K, Sasaki Y, Magistro D, Kawashima R. Effects of training of shadowing and reading aloud of second language on working memory and neural systems. Brain Imaging Behav 2021; 15:1253-1269. [PMID: 32705465 PMCID: PMC8286220 DOI: 10.1007/s11682-020-00324-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Shadowing and reading aloud both involve multiple complex cognitive processes, and both are considered effective methods for second-language learning. The working memory system, particularly the phonological loop, has been suggested to be involved in shadowing and reading aloud. The purpose of this study was to investigate the effects of a 4-week intensive adaptive training including shadowing and reading aloud of second language on working-memory capacity, regional gray matter volume (rGMV), and functional activation related to the n-back working-memory task in young adults. The results showed that compared with the training groups without speaking (listening to compressed speech and active control involving the second language), the training groups with speaking (shadowing and reading aloud) showed a tendency for greater test-retest increases in digit-span scores, and significantly greater test-retest decreases in N-back task reaction time (increase in working memory performance). Imaging analyses revealed compared with the active control group, shadowing group exhibited decreases in rGMV and brain activity during the working memory task (2-back task), in the left cerebellum and reading group exhibited decreases in them in the right anterior insula. These regions are parts of the phonological loop, suggesting the presence of training-induced neural plasticity in these neurocognitive mechanisms.
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Affiliation(s)
- Hikaru Takeuchi
- Division of Developmental Cognitive Neuroscience, Institute of Development, Aging and Cancer, Tohoku University, 4 - 1 Seiryo-cho, Aoba-ku, Sendai, 980-8575, Japan.
| | | | - Yasuyuki Taki
- Division of Developmental Cognitive Neuroscience, Institute of Development, Aging and Cancer, Tohoku University, 4 - 1 Seiryo-cho, Aoba-ku, Sendai, 980-8575, Japan
- Department of Community Medical Supports, Tohoku Medical Megabank Organization, Division of Medical Neuroimaging Analysis, Tohoku University, Sendai, Japan
- Department of Nuclear Medicine and Radiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Kosuke Motoki
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
| | - Hyeonjeong Jeong
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Yuka Kotozaki
- Division of Clinical research, Medical-Industry Translational Research Center, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Takamitsu Shinada
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
| | - Seishu Nakagawa
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
- Division of Psychiatry, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Rui Nouchi
- Human and Social Response Research Division, International Research Institute of Disaster Science, Tohoku University, Sendai, Japan
- Smart Ageing International Research Center, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Kunio Iizuka
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
- Department of Psychiatry, Tohoku University Graduate School of Medicine, Sendai, Japan
| | | | - Yuki Yamamoto
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
| | - Sugiko Hanawa
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
| | - Tsuyoshi Araki
- Smart Ageing International Research Center, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Kohei Sakaki
- Advanced Brain Science, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Yukako Sasaki
- Advanced Brain Science, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Daniele Magistro
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Ryuta Kawashima
- Faculty of Medicine, Tohoku University, Sendai, Japan
- Graduate School of International Cultural Studies, Tohoku University, Sendai, Japan
- Smart Ageing International Research Center, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
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14
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Ueta Y, Miyata M. Brainstem local microglia induce whisker map plasticity in the thalamus after peripheral nerve injury. Cell Rep 2021; 34:108823. [PMID: 33691115 DOI: 10.1016/j.celrep.2021.108823] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 01/13/2021] [Accepted: 02/12/2021] [Indexed: 12/18/2022] Open
Abstract
Whisker deafferentation in mice disrupts topographic connectivity from the brainstem to the thalamic ventral posteromedial nucleus (VPM), which represents whisker map, by recruiting "ectopic" axons carrying non-whisker information in VPM. However, mechanisms inducing this plasticity remain largely unknown. Here, we show the role of region-specific microglia in the brainstem principal trigeminal nucleus (Pr5), a whisker sensory-recipient region, in VPM whisker map plasticity. Systemic or local manipulation of microglial activity reveals that microglia in Pr5, but not in VPM, are necessary and sufficient for recruiting ectopic axons in VPM. Deafferentation causes membrane hyperexcitability of Pr5 neurons dependent on microglia. Inactivation of Pr5 neurons abolishes this somatotopic reorganization in VPM. Additionally, microglial depletion prevents deafferentation-induced ectopic mechanical hypersensitivity. Our results indicate that local microglia in the brainstem induce peripheral nerve injury-induced plasticity of map organization in the thalamus and suggest that microglia are potential therapeutic targets for peripheral nerve injury-induced mechanical hypersensitivity.
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Affiliation(s)
- Yoshifumi Ueta
- Division of Neurophysiology, Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo 162-8666, Japan.
| | - Mariko Miyata
- Division of Neurophysiology, Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo 162-8666, Japan.
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15
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Mojtahedi S, Shabkhiz F, Ravasi AA, Rosenkranz S, Soori R, Soleimani M, Tavakoli R. Voluntary wheel running promotes improvements in biomarkers associated with neurogenic activity in adult male rats. Biochem Biophys Res Commun 2020; 533:1505-1511. [PMID: 33139016 DOI: 10.1016/j.bbrc.2020.09.110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/24/2020] [Indexed: 01/01/2023]
Abstract
In rodents, hippocampal neurogenesis and synaptogenesis phenomena are affected by exercise. However, the role of exercise parameters such as intensity, duration, and mode on molecular mechanisms involved in these processes has not been elucidated. In this study, we evaluated the effects of different intensities and modes of running on the expression of genes contributing to neuronal differentiation and synapse formation in the hippocampus of adult male rats. Adult male Wistar rats (n = 24) were randomly divided into control, low-intensity running (LIR), high-intensity running (HIR), and the voluntary wheel running (WR) conditions. Changes in the expression of microRNA-124 (miR-124), microRNA-132 (miR-132), and their respective targets, were analyzed using quantitative RT-PCR and Western blotting techniques. Our results showed that WR compared to treadmill running increased miR-124 and miR-132 expression, while reducing the expression of their respective targets, glucocorticoid receptor (GR), SRY-Box 9 (SOX9), and GTP-activated protein P250 (P250GAP). Differences in expression levels were statistically significant (ps < 0.05), except for the expression of GR in HIR (P = 0.09). Moreover, the expression level of gene coding for the transcription factor cAMP-response element binding protein (CREB) was significantly higher in the WR group compared to the treadmill running groups (P = 0.001). Western blotting techniques indicated that the level of the CREB protein was higher in WR compared to the other groups qualitatively. These findings demonstrated a more dramatic effect for voluntary running on biomarkers that are associated with stimulating neurogenesis and synapse formation in the hippocampus of male rats compared with forced treadmill running. In addition, greater positive effects were observed for lower-intensity treadmill running as compared with high-intensity running.
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Affiliation(s)
- Shima Mojtahedi
- Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran.
| | - Fatemeh Shabkhiz
- Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran
| | - Ali Asghar Ravasi
- Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran
| | - Sara Rosenkranz
- School of Science and Health, University of Western Sydney, Sydney, Australia; Department of Food, Nutrition, Dietetics and Health, Kansas State University, Manhattan, KS, USA
| | - Rahman Soori
- Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran
| | | | - Rezvan Tavakoli
- Molecular Department, Pasteur Institute of Iran, Tehran, Iran
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16
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Salvadores N, Gerónimo-Olvera C, Court FA. Axonal Degeneration in AD: The Contribution of Aβ and Tau. Front Aging Neurosci 2020; 12:581767. [PMID: 33192476 PMCID: PMC7593241 DOI: 10.3389/fnagi.2020.581767] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/09/2020] [Indexed: 12/25/2022] Open
Abstract
Alzheimer's disease (AD) represents the most common age-related neurodegenerative disorder, affecting around 35 million people worldwide. Despite enormous efforts dedicated to AD research over decades, there is still no cure for the disease. Misfolding and accumulation of Aβ and tau proteins in the brain constitute a defining signature of AD neuropathology, and mounting evidence has documented a link between aggregation of these proteins and neuronal dysfunction. In this context, progressive axonal degeneration has been associated with early stages of AD and linked to Aβ and tau accumulation. As the axonal degeneration mechanism has been starting to be unveiled, it constitutes a promising target for neuroprotection in AD. A comprehensive understanding of the mechanism of axonal destruction in neurodegenerative conditions is therefore critical for the development of new therapies aimed to prevent axonal loss before irreversible neuronal death occurs in AD. Here, we review current evidence of the involvement of Aβ and tau pathologies in the activation of signaling cascades that can promote axonal demise.
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Affiliation(s)
- Natalia Salvadores
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile.,Fondap Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Cristian Gerónimo-Olvera
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile.,Fondap Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Felipe A Court
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile.,Fondap Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,Buck Institute for Research on Aging, Novato, CA, United States
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17
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Huang M, de Koning TJ, Tijssen MAJ, Verbeek DS. Cross-disease analysis of depression, ataxia and dystonia highlights a role for synaptic plasticity and the cerebellum in the pathophysiology of these comorbid diseases. Biochim Biophys Acta Mol Basis Dis 2020; 1867:165976. [PMID: 33011198 DOI: 10.1016/j.bbadis.2020.165976] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/15/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND There is growing evidence that the neuropsychiatric and neurological disorders depression, ataxia and dystonia share common biological pathways. We therefore aimed to increase our understanding of their shared pathophysiology by investigating their shared biological pathways and molecular networks. METHODS We constructed gene sets for depression, ataxia, and dystonia using the Human Phenotype Ontology database and genome-wide association studies, and identified shared genes between the three diseases. We then assessed shared genes in terms of functional enrichment, pathway analysis, molecular connectivity, expression profiles and brain-tissue-specific gene co-expression networks. RESULTS The 33 genes shared by depression, ataxia and dystonia are enriched in shared biological pathways and connected through molecular complexes in protein-protein interaction networks. Biological processes common/shared to all three diseases were identified across different brain tissues, highlighting roles for synaptic transmission, synaptic plasticity and nervous system development. The average expression of shared genes was significantly higher in the cerebellum compared to other brain regions, suggesting these genes have distinct cerebellar functions. Several shared genes also showed high expression in the cerebellum during prenatal stages, pointing to a functional role during development. CONCLUSIONS The shared pathophysiology of depression, ataxia and dystonia seems to converge onto the cerebellum that maybe particularly vulnerable to changes in synaptic transmission, regulation of synaptic plasticity and nervous system development. Consequently, in addition to regulating motor coordination and motor function, the cerebellum may likely play a role in mood processing.
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Affiliation(s)
- Miaozhen Huang
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Tom J de Koning
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; Pediatrics, Department of Clinical Sciences, Lund University, Sweden
| | - Marina A J Tijssen
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Dineke S Verbeek
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
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18
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Dahan L, Rampon C, Florian C. Age-related memory decline, dysfunction of the hippocampus and therapeutic opportunities. Prog Neuropsychopharmacol Biol Psychiatry 2020; 102:109943. [PMID: 32298784 DOI: 10.1016/j.pnpbp.2020.109943] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 04/01/2020] [Accepted: 04/01/2020] [Indexed: 12/13/2022]
Abstract
While the aging of the population is a sign of progress for societies, it also carries its load of negative aspects. Among them, cognitive decline and in particular memory loss is a common feature of non-pathological aging. Autobiographical memories, which rely on the hippocampus, are a primary target of age-related cognitive decline. Here, focusing on the neurobiological mechanisms of memory formation and storage, we describe how hippocampal functions are altered across time in non-pathological mammalian brains. Several hallmarks of aging have been well described over the last decades; among them, we consider altered synaptic communication and plasticity, reduction of adult neurogenesis and epigenetic alterations. Building on the neurobiological processes of cognitive aging that have been identified to date, we review some of the strategies based on lifestyle manupulation allowing to address age-related cognitive deficits.
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Affiliation(s)
- Lionel Dahan
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse Cedex 9, France
| | - Claire Rampon
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse Cedex 9, France
| | - Cédrick Florian
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse Cedex 9, France.
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19
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Fontaine CJ, Gräfe EL, Pinar C, Bonilla-Del Río I, Grandes P, Christie BR. Endocannabinoid receptors contribute significantly to multiple forms of long-term depression in the rat dentate gyrus. LEARNING & MEMORY (COLD SPRING HARBOR, N.Y.) 2020; 27:380-389. [PMID: 32817304 PMCID: PMC7433656 DOI: 10.1101/lm.050666.119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/02/2020] [Indexed: 12/12/2022]
Abstract
Cannabinoid receptors are widely expressed throughout the hippocampal formation, but are particularly dense in the dentate gyrus (DG) subregion. We, and others, have shown in mice that cannabinoid type 1 receptors (CB1Rs) are involved in a long-term depression (LTD) that can be induced by prolonged 10 Hz stimulation of the medial perforant path (MPP)-granule cell synaptic input to the DG. Here, we extend this work to examine the involvement of CB1Rs in other common forms of LTD in the hippocampus of juvenile male and female Sprague–Dawley rats (Rattus norvegicus). We found, as in mice, that prolonged 10 Hz stimulation (6000 pulses) could reliably induce a form of LTD that was dependent upon CB1R activation. In addition, we also discovered a role for both CB1R and mGluR proteins in LTD induced with 1 Hz low-frequency stimulation (1 Hz-LTD; 900 pulses) and in LTD induced by bath application of the group I mGluR agonist (RS)-3,5-Dihydroxyphenylglycine (DHPG; DHPG-LTD). This study elucidates an essential role for endocannabinoid receptors in a number of forms of LTD in the rat DG, and identifies a novel role for CB1Rs as potential therapeutic targets for conditions that involve impaired LTD in the DG.
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Affiliation(s)
- Christine J Fontaine
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
| | - Erin L Gräfe
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
| | - Cristina Pinar
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
| | - Itziar Bonilla-Del Río
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, E-48940 Leioa, Spain.,Achucarro Basque Center for Neuroscience, Science Park of the University of the Basque Country UPV/EHU, E-48940 Leioa, Spain
| | - Pedro Grandes
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada.,Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, E-48940 Leioa, Spain.,Achucarro Basque Center for Neuroscience, Science Park of the University of the Basque Country UPV/EHU, E-48940 Leioa, Spain
| | - Brian R Christie
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada.,Island Medical Program and Department of Cellular and Physiological Sciences, University of British Columbia, Victoria, British Columbia, USA
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20
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Allene C, Kalalou K, Durand F, Thomas F, Januel D. Acute and Post-Traumatic Stress Disorders: A biased nervous system. Rev Neurol (Paris) 2020; 177:23-38. [PMID: 32800536 DOI: 10.1016/j.neurol.2020.05.010] [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: 05/09/2019] [Revised: 05/15/2020] [Accepted: 05/20/2020] [Indexed: 11/24/2022]
Abstract
Acute stress disorder and post-traumatic stress disorder are generally triggered by an exceptionally intense threat. The consequences of this traumatogenic situation are explored here in chronological order, from exposure to the threat to development of symptoms. Such a situation may disrupt the equilibrium between two fundamental brain circuits, referred to as the "defensive" and "cognitive". The defensive circuit triggers the stress response as well as the formation of implicit memory. The cognitive circuit triggers the voluntary response and the formation of explicit autobiographical memory. During a traumatogenic situation, the defensive circuit could be over-activated while cognitive circuit is under-activated. In the most severe cases, overactivation of the defensive circuit may cause its brutal deactivation, resulting in dissociation. Here, we address the underlying neurobiological mechanisms at every scale: from neurons to behaviors, providing a detailed explanatory model of trauma.
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Affiliation(s)
- C Allene
- Unité de recherche clinique, établissement public de santé Ville-Evrard, 202, avenue Jean-Jaurès, 93332 Neuilly-sur-Marne, France; Centre de psychothérapie, établissement public de santé Ville-Evrard, 5, rue du Docteur-Delafontaine, 93200 Saint-Denis, France.
| | - K Kalalou
- Unité de recherche clinique, établissement public de santé Ville-Evrard, 202, avenue Jean-Jaurès, 93332 Neuilly-sur-Marne, France; Centre de psychothérapie, établissement public de santé Ville-Evrard, 5, rue du Docteur-Delafontaine, 93200 Saint-Denis, France.
| | - F Durand
- Unité de recherche clinique, établissement public de santé Ville-Evrard, 202, avenue Jean-Jaurès, 93332 Neuilly-sur-Marne, France; Centre de psychothérapie, établissement public de santé Ville-Evrard, 5, rue du Docteur-Delafontaine, 93200 Saint-Denis, France.
| | - F Thomas
- Unité de recherche clinique, établissement public de santé Ville-Evrard, 202, avenue Jean-Jaurès, 93332 Neuilly-sur-Marne, France.
| | - D Januel
- Unité de recherche clinique, établissement public de santé Ville-Evrard, 202, avenue Jean-Jaurès, 93332 Neuilly-sur-Marne, France.
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21
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Najm R, Zalocusky KA, Zilberter M, Yoon SY, Hao Y, Koutsodendris N, Nelson M, Rao A, Taubes A, Jones EA, Huang Y. In Vivo Chimeric Alzheimer's Disease Modeling of Apolipoprotein E4 Toxicity in Human Neurons. Cell Rep 2020; 32:107962. [PMID: 32726626 PMCID: PMC7430173 DOI: 10.1016/j.celrep.2020.107962] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/15/2020] [Accepted: 07/03/2020] [Indexed: 02/08/2023] Open
Abstract
Despite its clear impact on Alzheimer's disease (AD) risk, apolipoprotein (apo) E4's contributions to AD etiology remain poorly understood. Progress in answering this and other questions in AD research has been limited by an inability to model human-specific phenotypes in an in vivo environment. Here we transplant human induced pluripotent stem cell (hiPSC)-derived neurons carrying normal apoE3 or pathogenic apoE4 into human apoE3 or apoE4 knockin mouse hippocampi, enabling us to disentangle the effects of apoE4 produced in human neurons and in the brain environment. Using single-nucleus RNA sequencing (snRNA-seq), we identify key transcriptional changes specific to human neuron subtypes in response to endogenous or exogenous apoE4. We also find that Aβ from transplanted human neurons forms plaque-like aggregates, with differences in localization and interaction with microglia depending on the transplant and host apoE genotype. These findings highlight the power of in vivo chimeric disease modeling for studying AD.
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Affiliation(s)
- Ramsey Najm
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Developmental and Stem Cell Biology Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Kelly A Zalocusky
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Gladstone Center for Translational Advancement, San Francisco, CA 94158, USA
| | - Misha Zilberter
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Seo Yeon Yoon
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Yanxia Hao
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Gladstone Center for Translational Advancement, San Francisco, CA 94158, USA
| | - Nicole Koutsodendris
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Developmental and Stem Cell Biology Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Maxine Nelson
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Antara Rao
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Developmental and Stem Cell Biology Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Alice Taubes
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Emily A Jones
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Yadong Huang
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Developmental and Stem Cell Biology Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA; Gladstone Center for Translational Advancement, San Francisco, CA 94158, USA; Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA; Departments of Neurology and Pathology, University of California, San Francisco, San Francisco, CA 94143, USA.
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22
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Chen SH, Papaneri A, Walker M, Scappini E, Keys RD, Martin NP. A Simple, Two-Step, Small-Scale Purification of Recombinant Adeno-Associated Viruses. J Virol Methods 2020; 281:113863. [PMID: 32371233 DOI: 10.1016/j.jviromet.2020.113863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/22/2020] [Accepted: 04/03/2020] [Indexed: 10/24/2022]
Abstract
Recombinant adeno-associated viruses (rAAVs) are robust and versatile tools for in vivo gene delivery. Natural and designer capsid variations in rAAVs allow for targeted gene delivery to specific cell types. Low immunogenicity and lack of pathogenesis also add to the popularity of this virus as an innocuous gene delivery vector for gene therapy. rAAVs are routinely used to express recombinases, sensors, detectors, CRISPR-Cas9 components, or to simply overexpress a gene of interest for functional studies. High production demand has given rise to multiple platforms for the production and purification of rAAVs. However, most platforms rely heavily on large amounts of starting material and multiple purification steps to produce highly purified viral particles. Often, researchers require several small-scale purified rAAVs. Here, we describe a simple and efficient technique for purification of recombinant rAAVs from small amounts of starting material in a two-step purification method. In this method, rAAVs are released into the packaging cell medium using high salt concentration, pelleted by ultracentrifugation to remove soluble impurities. Then, the resuspended pellet is purified using a protein spin-concentrator. In this protocol, we modify the conventional rAAV purification methods to eliminate the need for fraction collection and the labor-intensive steps for evaluating the titer and purity of individual fractions. The resulting rAAV preparations are comparable in titer and purity to commercially available samples. This simplified process can be used to generate highly purified rAAV particles on a small scale, thereby saving resources, generating less waste, and reducing a laboratory's environmental footprint.
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Affiliation(s)
- Shih-Heng Chen
- Neurobiology Laboratory, U.S.A; Viral Vector Core, U.S.A
| | | | - Mitzie Walker
- Neurobiology Laboratory, U.S.A; Viral Vector Core, U.S.A
| | | | - Robert D Keys
- Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences, NIH/DHHS, 111 T.W. Alexander Drive, Research Triangle Park, N.C. 27709, U.S.A
| | - Negin P Martin
- Neurobiology Laboratory, U.S.A; Viral Vector Core, U.S.A.
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23
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Rochford AE, Carnicer-Lombarte A, Curto VF, Malliaras GG, Barone DG. When Bio Meets Technology: Biohybrid Neural Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903182. [PMID: 31517403 DOI: 10.1002/adma.201903182] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/06/2019] [Indexed: 06/10/2023]
Abstract
The development of electronics capable of interfacing with the nervous system is a rapidly advancing field with applications in basic science and clinical translation. Devices containing arrays of electrodes can be used in the study of cells grown in culture or can be implanted into damaged or dysfunctional tissue to restore normal function. While devices are typically designed and used exclusively for one of these two purposes, there have been increasing efforts in developing implantable electrode arrays capable of housing cultured cells, referred to as biohybrid implants. Once implanted, the cells within these implants integrate into the tissue, serving as a mediator of the electrode-tissue interface. This biological component offers unique advantages to these implant designs, providing better tissue integration and potentially long-term stability. Herein, an overview of current research into biohybrid devices, as well as the historical background that led to their development are provided, based on the host anatomical location for which they are designed (CNS, PNS, or special senses). Finally, a summary of the key challenges of this technology and potential future research directions are presented.
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Affiliation(s)
- Amy E Rochford
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | | | - Vincenzo F Curto
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | - George G Malliaras
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | - Damiano G Barone
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
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Cardozo PL, de Lima IBQ, Maciel EMA, Silva NC, Dobransky T, Ribeiro FM. Synaptic Elimination in Neurological Disorders. Curr Neuropharmacol 2020; 17:1071-1095. [PMID: 31161981 PMCID: PMC7052824 DOI: 10.2174/1570159x17666190603170511] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/23/2019] [Accepted: 05/31/2019] [Indexed: 12/12/2022] Open
Abstract
Synapses are well known as the main structures responsible for transmitting information through the release and recognition of neurotransmitters by pre- and post-synaptic neurons. These structures are widely formed and eliminated throughout the whole lifespan via processes termed synaptogenesis and synaptic pruning, respectively. Whilst the first pro-cess is needed for ensuring proper connectivity between brain regions and also with the periphery, the second phenomenon is important for their refinement by eliminating weaker and unnecessary synapses and, at the same time, maintaining and fa-voring the stronger ones, thus ensuring proper synaptic transmission. It is well-known that synaptic elimination is modulated by neuronal activity. However, only recently the role of the classical complement cascade in promoting this phenomenon has been demonstrated. Specifically, microglial cells recognize activated complement component 3 (C3) bound to synapses tar-geted for elimination, triggering their engulfment. As this is a highly relevant process for adequate neuronal functioning, dis-ruptions or exacerbations in synaptic pruning could lead to severe circuitry alterations that could underlie neuropathological alterations typical of neurological and neuropsychiatric disorders. In this review, we focus on discussing the possible in-volvement of excessive synaptic elimination in Alzheimer’s disease, as it has already been reported dendritic spine loss in post-synaptic neurons, increased association of complement proteins with its synapses and, hence, augmented microglia-mediated pruning in animal models of this disorder. In addition, we briefly discuss how this phenomenon could be related to other neurological disorders, including multiple sclerosis and schizophrenia.
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Affiliation(s)
- Pablo L Cardozo
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Izabella B Q de Lima
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Esther M A Maciel
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Nathália C Silva
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Fabíola M Ribeiro
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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25
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Hajszan T. Stress and remodeling of hippocampal spine synapses. VITAMINS AND HORMONES 2020; 114:257-279. [DOI: 10.1016/bs.vh.2020.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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26
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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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Chidambaram SB, Rathipriya AG, Bolla SR, Bhat A, Ray B, Mahalakshmi AM, Manivasagam T, Thenmozhi AJ, Essa MM, Guillemin GJ, Chandra R, Sakharkar MK. Dendritic spines: Revisiting the physiological role. Prog Neuropsychopharmacol Biol Psychiatry 2019; 92:161-193. [PMID: 30654089 DOI: 10.1016/j.pnpbp.2019.01.005] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 01/04/2019] [Accepted: 01/12/2019] [Indexed: 12/11/2022]
Abstract
Dendritic spines are small, thin, specialized protrusions from neuronal dendrites, primarily localized in the excitatory synapses. Sophisticated imaging techniques revealed that dendritic spines are complex structures consisting of a dense network of cytoskeletal, transmembrane and scaffolding molecules, and numerous surface receptors. Molecular signaling pathways, mainly Rho and Ras family small GTPases pathways that converge on actin cytoskeleton, regulate the spine morphology and dynamics bi-directionally during synaptic activity. During synaptic plasticity the number and shapes of dendritic spines undergo radical reorganizations. Long-term potentiation (LTP) induction promote spine head enlargement and the formation and stabilization of new spines. Long-term depression (LTD) results in their shrinkage and retraction. Reports indicate increased spine density in the pyramidal neurons of autism and Fragile X syndrome patients and reduced density in the temporal gyrus loci of schizophrenic patients. Post-mortem reports of Alzheimer's brains showed reduced spine number in the hippocampus and cortex. This review highlights the spine morphogenesis process, the activity-dependent structural plasticity and mechanisms by which synaptic activity sculpts the dendritic spines, the structural and functional changes in spines during learning and memory using LTP and LTD processes. It also discusses on spine status in neurodegenerative diseases and the impact of nootropics and neuroprotective agents on the functional restoration of dendritic spines.
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Affiliation(s)
- Saravana Babu Chidambaram
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India.
| | - A G Rathipriya
- Food and Brain Research Foundation, Chennai, Tamil Nadu, India
| | - Srinivasa Rao Bolla
- Department of Anatomy, College of Medicine, Imam Abdulrahman Bin Faisal University, Damam, Saudi Arabia
| | - Abid Bhat
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Bipul Ray
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Arehally Marappa Mahalakshmi
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Thamilarasan Manivasagam
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamilnadu, India
| | - Arokiasamy Justin Thenmozhi
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamilnadu, India
| | - Musthafa Mohamed Essa
- Department of Food Science and Nutrition, CAMS, Sultan Qaboos University, Muscat, Oman
| | - Gilles J Guillemin
- Neuropharmacology Group, Faculty of Medicine and Health Sciences, Deb Bailey MND Research Laboratory, Macquarie University, Sydney, NSW 2109, Australia
| | - Ramesh Chandra
- Department of Chemistry, Ambedkar Centre for BioMedical Research, Delhi University, Delhi 110007, India
| | - Meena Kishore Sakharkar
- College of Pharmacy and Nutrition, University of Saskatchewan, 107, Wiggins Road, Saskatoon, SK S7N 5C9, Canada.
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28
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Synapse loss and progress of Alzheimer's disease -A network model. Sci Rep 2019; 9:6555. [PMID: 31024073 PMCID: PMC6484103 DOI: 10.1038/s41598-019-43076-y] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 04/08/2019] [Indexed: 12/27/2022] Open
Abstract
We present observational evidence from studies on primary cortical cultures from AD transgenic mice, APPSwe/PS1ΔE9 (APP/PS1) mice, for significant decrease in total spine density at DIV-15 and onward. This indicates reduction in potential healthy synapses and strength of connections among neurons. Based on this, a network model of neurons is developed, that explains the consequent loss of coordinated activity and transmission efficiency among neurons that manifests over time. The critical time when structural connectivity in the brain undergoes a phase-transition, from initial robustness to irreparable breakdown, is estimated from this model. We also show how the global efficiency of signal transmission in the network decreases over time. Moreover, the number of multiple paths of high efficiency decreases rapidly as the disease progresses, indicating loss of structural plasticity and inefficiency in choosing alternate paths or desired paths for any pattern of activity. Thus loss of spines caused by β-Amyloid (Aβ) peptide results in disintegration of the neuronal network over time with consequent cognitive dysfunctions in Alzheimer’s Disease (AD).
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Lee K, Vyas Y, Garner CC, Montgomery JM. Autism‐associated
Shank3
mutations alter mGluR expression and mGluR‐dependent but not NMDA receptor‐dependent long‐term depression. Synapse 2019; 73:e22097. [DOI: 10.1002/syn.22097] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/20/2019] [Accepted: 03/10/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Kevin Lee
- Department of Physiology, Centre for Brain Research University of Auckland Auckland New Zealand
| | - Yukti Vyas
- Department of Physiology, Centre for Brain Research University of Auckland Auckland New Zealand
| | - Craig C. Garner
- German Center for Neurodegenerative Disorders Charité – Universitätsmedizin Berlin Berlin Germany
| | - Johanna M. Montgomery
- Department of Physiology, Centre for Brain Research University of Auckland Auckland New Zealand
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30
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Chen SH, Haam J, Walker M, Scappini E, Naughton J, Martin NP. Production of Viral Constructs for Neuroanatomy, Calcium Imaging, and Optogenetics. ACTA ACUST UNITED AC 2019; 87:e66. [PMID: 30883041 DOI: 10.1002/cpns.66] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Advances in design and use of light-sensitive and light-emitting sensors have facilitated observation, measurement, and control of neuronal activities. Viruses are effective vectors for delivery of these valuable research tools to mammalian brains. Recombinant viruses are optimized to mediate regulatable, long-term, and cell-specific gene expression. Here, we describe production methods for three of the most commonly used types of recombinant viruses in neurobiology research: adeno-associated virus (AAV), retrovirus/lentivirus, and glycoprotein-deleted rabies virus. These viral constructs are frequently used for calcium imaging or to deliver neural tracers and optogenetic tools. Popular constructs are readily obtained commercially; however, customized virus production through commercial sources is time consuming and costly. This article aims to provide readers with detailed technical information for rapid production and validation of high-quality viral particles in a laboratory setting while highlighting advantages and limitations of each viral type. © 2019 by John Wiley & Sons, Inc.
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Affiliation(s)
- Shih-Heng Chen
- Viral Vector Core, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
| | - Juhee Haam
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
| | - Mitzie Walker
- Viral Vector Core, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
| | - Erica Scappini
- Signal Transduction Laboratory, Fluorescence Microscopy and Imaging Center, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
| | - John Naughton
- Gene Transfer, Targeting and Therapeutics (GT3) Core, Salk Institute for Biological Studies, La Jolla, California
| | - Negin P Martin
- Viral Vector Core, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, NIH/DHHS, Research Triangle Park, North Carolina
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31
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Djurisic M, Brott BK, Saw NL, Shamloo M, Shatz CJ. Activity-dependent modulation of hippocampal synaptic plasticity via PirB and endocannabinoids. Mol Psychiatry 2019; 24:1206-1219. [PMID: 29670176 PMCID: PMC6372352 DOI: 10.1038/s41380-018-0034-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 01/21/2018] [Accepted: 01/31/2018] [Indexed: 12/18/2022]
Abstract
The threshold for Hebbian synaptic plasticity in the CNS is modulated by prior synaptic activity. At adult CA3-CA1 synapses, endocannabinoids play a role in this process, but how activity engages and maintains this retrograde signaling system is not well understood. Here we show that conditional deletion of Paired Immunoglobulin-like receptor B (PirB) from pyramidal neurons in adult mouse hippocampus results in deficient LTD at CA3-CA1 synapses over a range of stimulation frequencies, accompanied by an increase in LTP. This finding can be fully explained by the disengagement of retrograde endocannabinoid signaling selectively at excitatory synapses. In the absence of PirB, the NMDAR-dependent regulation of endocannabinoid signaling is lost, while CB1R-dependent and group I mGluR-dependent regulation are intact. Moreover, mEPSC frequency in mutant CA1 pyramidal cells is elevated, consistent with a higher density of excitatory synapses and altered synapse pruning. Mice lacking PirB also perform better than WT in learning and memory tasks. These observations suggest that PirB is an integral part of an NMDA receptor-mediated synaptic mechanism that maintains bidirectional Hebbian plasticity and learning via activity-dependent endocannabinoid signaling.
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Affiliation(s)
- Maja Djurisic
- Departments of Biology and Neurobiology, and Bio-X, Stanford University, Stanford, CA, 94305, USA.
| | - Barbara K. Brott
- 0000000419368956grid.168010.eDepartments of Biology and Neurobiology, and Bio-X, Stanford University, Stanford, CA 94305 USA
| | - Nay L. Saw
- 0000000419368956grid.168010.eBehavioral and Functional Neuroscience Laboratory, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Mehrdad Shamloo
- 0000000419368956grid.168010.eBehavioral and Functional Neuroscience Laboratory, Stanford University School of Medicine, Stanford, CA 94305 USA ,0000000419368956grid.168010.eBehavioral and Functional Neuroscience Laboratory and Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Carla J. Shatz
- 0000000419368956grid.168010.eDepartments of Biology and Neurobiology, and Bio-X, Stanford University, Stanford, CA 94305 USA
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Li S, Jin M, Liu L, Dang Y, Ostaszewski BL, Selkoe DJ. Decoding the synaptic dysfunction of bioactive human AD brain soluble Aβ to inspire novel therapeutic avenues for Alzheimer's disease. Acta Neuropathol Commun 2018; 6:121. [PMID: 30409172 PMCID: PMC6225562 DOI: 10.1186/s40478-018-0626-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 10/29/2018] [Indexed: 12/31/2022] Open
Abstract
Pathologic, biochemical and genetic evidence indicates that accumulation and aggregation of amyloid β-proteins (Aβ) is a critical factor in the pathogenesis of Alzheimer's disease (AD). Several therapeutic interventions attempting to lower Aβ have failed to ameliorate cognitive decline in patients with clinical AD significantly, but most such approaches target only one or two facets of Aβ production/clearance/toxicity and do not consider the heterogeneity of human Aβ species. As synaptic dysfunction may be among the earliest deficits in AD, we used hippocampal long-term potentiation (LTP) as a sensitive indicator of the early neurotoxic effects of Aβ species. Here we confirmed prior findings that soluble Aβ oligomers, much more than fibrillar amyloid plaque cores or Aβ monomers, disrupt synaptic function. Interestingly, not all (84%) human AD brain extracts are able to inhibit LTP and the degree of LTP impairment by AD brain extracts does not correlate with Aβ levels detected by standard ELISAs. Bioactive AD brain extracts also induce neurotoxicity in iPSC-derived human neurons. Shorter forms of Aβ (including Aβ1-37, Aβ1-38, Aβ1-39), pre-Aβ APP fragments (- 30 to - 1) and N-terminally extended Aβs (- 30 to + 40) each showed much less synaptotoxicity than longer Aβs (Aβ1-42 - Aβ1-46). We found that antibodies which target the N-terminus, not the C-terminus, efficiently rescued Aβ oligomer-impaired LTP and oligomer-facilitated LTD. Our data suggest that preventing soluble Aβ oligomer formation and targeting their N-terminal residues with antibodies could be an attractive combined therapeutic approach.
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Wiegert JS, Pulin M, Gee CE, Oertner TG. The fate of hippocampal synapses depends on the sequence of plasticity-inducing events. eLife 2018; 7:39151. [PMID: 30311904 PMCID: PMC6205809 DOI: 10.7554/elife.39151] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 10/11/2018] [Indexed: 01/31/2023] Open
Abstract
Synapses change their strength in response to specific activity patterns. This functional plasticity is assumed to be the brain’s primary mechanism for information storage. We used optogenetic stimulation of rat hippocampal slice cultures to induce long-term potentiation (LTP), long-term depression (LTD), or both forms of plasticity in sequence. Two-photon imaging of spine calcium signals allowed us to identify stimulated synapses and to follow their fate for the next 7 days. We found that plasticity-inducing protocols affected the synapse’s chance for survival: LTP increased synaptic stability, LTD destabilized synapses, and the effect of the last stimulation protocol was dominant over earlier stimulations. Interestingly, most potentiated synapses were resistant to depression-inducing protocols delivered 24 hr later. Our findings suggest that activity-dependent changes in the transmission strength of individual synapses are transient, but have long-lasting consequences for synaptic lifetime.
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Affiliation(s)
- J Simon Wiegert
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mauro Pulin
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christine Elizabeth Gee
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas G Oertner
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Abstract
Dynamic modification of synaptic connectivity in response to sensory experience is a vital step in the refinement of brain circuits as they are established during development and modified during learning. In addition to the well-established role for new spine growth and stabilization in the experience-dependent plasticity of neural circuits, dendritic spine elimination has been linked to improvements in learning, and dysregulation of spine elimination has been associated with intellectual disability and behavioral impairment. Proper brain function requires a tightly regulated balance between spine formation and spine elimination. Although most studies have focused on the mechanisms of spine formation, considerable progress has been made recently in delineating the neural activity patterns and downstream molecular mechanisms that drive dendritic spine elimination. Here, we review the current state of knowledge concerning the signaling pathways that drive dendritic spine shrinkage and elimination in the cerebral cortex and we discuss their implication in neuropsychiatric and neurodegenerative disease.
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Affiliation(s)
- Ivar S Stein
- 1 Center for Neuroscience, University of California, Davis, CA, USA
| | - Karen Zito
- 1 Center for Neuroscience, University of California, Davis, CA, USA
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35
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Suresh A, Dunaevsky A. Relationship Between Synaptic AMPAR and Spine Dynamics: Impairments in the FXS Mouse. Cereb Cortex 2018; 27:4244-4256. [PMID: 28541473 PMCID: PMC6057510 DOI: 10.1093/cercor/bhx128] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 05/04/2017] [Indexed: 12/26/2022] Open
Abstract
Structural dynamics of dendritic spines are important for memory and learning and are impaired in neurodevelopmental disorders such as fragile X syndrome. Spine dynamics are regulated by activity-dependent mechanisms that involve modulation of AMPA receptors (AMPAR); however, the relationship between AMPAR and spine dynamics in vivo and how these are altered in FXS mouse model is not known. Here, we tracked AMPAR and spines over multiple days in vivo in the cortex and found that dendritic spines in the fmr1 KO mouse were denser, smaller, had higher turnover rates and contained less sGluA2 compared to littermate controls. Although, KO spines maintained the relationship between AMPAR and spine stability, AMPAR levels in the KO were more dynamic with larger proportion of spines showing multiple dynamic events of AMPAR. Directional changes in sGluA2 were also observed in newly formed and eliminated spines, with KO spines displaying greater loss of AMPAR before elimination. Thus, we demonstrate that AMPAR levels within spines not are only continuously dynamic, but are also predictive of spine behavior, with impairments observed in the fmr1 KO mice.
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Affiliation(s)
| | - Anna Dunaevsky
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, 985960 Nebraska Medical Center, Omaha, NE 68198-5960, USA
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36
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Wilkerson JR, Albanesi JP, Huber KM. Roles for Arc in metabotropic glutamate receptor-dependent LTD and synapse elimination: Implications in health and disease. Semin Cell Dev Biol 2017; 77:51-62. [PMID: 28969983 DOI: 10.1016/j.semcdb.2017.09.035] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/21/2017] [Accepted: 09/26/2017] [Indexed: 10/18/2022]
Abstract
The Arc gene is robustly transcribed in specific neural ensembles in response to experience-driven activity. Upon induction, Arc mRNA is transported to dendrites, where it can be rapidly and locally translated by activation of metabotropic glutamate receptors (mGluR1/5). mGluR-induced dendritic synthesis of Arc is implicated in weakening or elimination of excitatory synapses by triggering endocytosis of postsynaptic AMPARs in both hippocampal CA1 and cerebellar Purkinje neurons. Importantly, CA1 neurons with experience-induced Arc mRNA are susceptible, or primed for mGluR-induced long-term synaptic depression (mGluR-LTD). Here we review mechanisms and function of Arc in mGluR-LTD and synapse elimination and propose roles for these forms of plasticity in Arc-dependent formation of sparse neural representations of learned experience. We also discuss accumulating evidence linking dysregulation of Arc and mGluR-LTD in human cognitive disorders such as intellectual disability, autism and Alzheimer's disease.
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Affiliation(s)
- Julia R Wilkerson
- Departments of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Joseph P Albanesi
- Departments of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Kimberly M Huber
- Departments of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States.
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Experience-Dependent Synaptic Plasticity in V1 Occurs without Microglial CX3CR1. J Neurosci 2017; 37:10541-10553. [PMID: 28951447 DOI: 10.1523/jneurosci.2679-16.2017] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/15/2017] [Accepted: 09/19/2017] [Indexed: 01/23/2023] Open
Abstract
Brief monocular deprivation (MD) shifts ocular dominance and reduces the density of thalamic synapses in layer 4 of the mouse primary visual cortex (V1). We found that microglial lysosome content is also increased as a result of MD. Previous studies have shown that the microglial fractalkine receptor CX3CR1 is involved in synaptic development and hippocampal plasticity. We therefore tested the hypothesis that neuron-to-microglial communication via CX3CR1 is an essential component of visual cortical development and plasticity in male mice. Our data show that CX3CR1 is not required for normal development of V1 responses to visual stimulation, multiple forms of experience-dependent plasticity, or the synapse loss that accompanies MD in layer 4. By ruling out an essential role for fractalkine signaling, our study narrows the search for understanding how microglia respond to active synapse modification in the visual cortex.SIGNIFICANCE STATEMENT Microglia in the visual cortex respond to monocular deprivation with increased lysosome content, but signaling through the fractalkine receptor CX3CR1 is not an essential component in the mechanisms of visual cortical development or experience-dependent synaptic plasticity.
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Strobl MTJ, Freeman D, Patel J, Poulsen R, Wendler CC, Rivkees SA, Coleman JE. Opposing Effects of Maternal Hypo- and Hyperthyroidism on the Stability of Thalamocortical Synapses in the Visual Cortex of Adult Offspring. Cereb Cortex 2017; 27:3015-3027. [PMID: 27235101 PMCID: PMC6059113 DOI: 10.1093/cercor/bhw096] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Insufficient or excessive thyroid hormone (TH) levels during fetal development can cause long-term neurological and cognitive problems. Studies in animal models of perinatal hypo- and hyperthyroidism suggest that these problems may be a consequence of the formation of maladaptive circuitry in the cerebral cortex, which can persist into adulthood. Here we used mouse models of maternal hypo- and hyperthyroidism to investigate the long-term effects of altering thyroxine (T4) levels during pregnancy (corresponding to embryonic days 6.5-18.5) on thalamocortical (TC) axon dynamics in adult offspring. Because perinatal hypothyroidism has been linked to visual processing deficits in humans, we performed chronic two-photon imaging of TC axons and boutons in primary visual cortex (V1). We found that a decrease or increase in maternal serum T4 levels was associated with atypical steady-state dynamics of TC axons and boutons in V1 of adult offspring. Hypothyroid offspring exhibited axonal branch and bouton dynamics indicative of an abnormal increase in TC connectivity, whereas changes in hyperthyroid offspring were indicative of an abnormal decrease in TC connectivity. Collectively, our data suggest that alterations to prenatal T4 levels can cause long-term synaptic instability in TC circuits, which could impair early stages of visual processing.
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Affiliation(s)
- Marie-Therese J. Strobl
- Department of Pediatrics, Child Health Research Institute,University of Florida College of Medicine, Gainesville, FL 32610, USA
- Department of Nuclear Medicine, University Medical Center, University RWTH Aachen, 52074 Aachen, Germany
| | - Daniel Freeman
- Department of Pediatrics, Child Health Research Institute,University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Jenica Patel
- Department of Pediatrics, Child Health Research Institute,University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Ryan Poulsen
- Department of Pediatrics, Child Health Research Institute,University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Christopher C. Wendler
- Department of Pediatrics, Child Health Research Institute,University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Scott A. Rivkees
- Department of Pediatrics, Child Health Research Institute,University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Jason E. Coleman
- Department of Pediatrics, Child Health Research Institute,University of Florida College of Medicine, Gainesville, FL 32610, USA
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Kondo Y, Yada Y, Haga T, Takayama Y, Isomura T, Jimbo Y, Fukayama O, Hoshino T, Mabuchi K. Temporal relation between neural activity and neurite pruning on a numerical model and a microchannel device with micro electrode array. Biochem Biophys Res Commun 2017; 486:539-544. [PMID: 28322793 DOI: 10.1016/j.bbrc.2017.03.082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 03/17/2017] [Indexed: 11/27/2022]
Abstract
Synapse elimination and neurite pruning are essential processes for the formation of neuronal circuits. These regressive events depend on neural activity and occur in the early postnatal days known as the critical period, but what makes this temporal specificity is not well understood. One possibility is that the neural activities during the developmentally regulated shift of action of GABA inhibitory transmission lead to the critical period. Moreover, it has been reported that the shifting action of the inhibitory transmission on immature neurons overlaps with synapse elimination and neurite pruning and that increased inhibitory transmission by drug treatment could induce temporal shift of the critical period. However, the relationship among these phenomena remains unclear because it is difficult to experimentally show how the developmental shift of inhibitory transmission influences neural activities and whether the activities promote synapse elimination and neurite pruning. In this study, we modeled synapse elimination in neuronal circuits using the modified Izhikevich's model with functional shifting of GABAergic transmission. The simulation results show that synaptic pruning within a specified period like the critical period is spontaneously generated as a function of the developmentally shifting inhibitory transmission and that the specific firing rate and increasing synchronization of neural circuits are seen at the initial stage of the critical period. This temporal relationship was experimentally supported by an in vitro primary culture of rat cortical neurons in a microchannel on a multi-electrode array (MEA). The firing rate decreased remarkably between the 18-25 days in vitro (DIV), and following these changes in the firing rate, the neurite density was slightly reduced. Our simulation and experimental results suggest that decreasing neural activity due to developing inhibitory synaptic transmission could induce synapse elimination and neurite pruning at particular time such as the critical period. Additionally, these findings indicate that we can estimate the maturity level of inhibitory transmission and the critical period by measuring the firing rate and the degree of synchronization in engineered neural networks.
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Affiliation(s)
- Yohei Kondo
- Department of Information Physics and Computing, The University of Tokyo, Tokyo 113-8656, Japan
| | - Yuichiro Yada
- Department of Mechano-Informatics, The University of Tokyo, Tokyo 113-8656, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan
| | - Tatsuya Haga
- Brain Science Institute, RIKEN, Saitama 351-0198, Japan
| | - Yuzo Takayama
- Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan
| | - Takuya Isomura
- Department of Human and Engineered Environmental Studies, The University of Tokyo, Tokyo 113-8656, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan
| | - Yasuhiko Jimbo
- Department of Precision Engineering, The University of Tokyo, Tokyo 113-8656, Japan; Department of Human and Engineered Environmental Studies, The University of Tokyo, Tokyo 113-8656, Japan
| | - Osamu Fukayama
- Department of Information Physics and Computing, The University of Tokyo, Tokyo 113-8656, Japan
| | - Takayuki Hoshino
- Department of Information Physics and Computing, The University of Tokyo, Tokyo 113-8656, Japan.
| | - Kunihiko Mabuchi
- Department of Information Physics and Computing, The University of Tokyo, Tokyo 113-8656, Japan
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Superresolution imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity. Proc Natl Acad Sci U S A 2017; 114:1401-1406. [PMID: 28115721 DOI: 10.1073/pnas.1607541114] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Axons convey information to nearby and distant cells, and the time it takes for action potentials (APs) to reach their targets governs the timing of information transfer in neural circuits. In the unmyelinated axons of hippocampus, the conduction speed of APs depends crucially on axon diameters, which vary widely. However, it is not known whether axon diameters are dynamic and regulated by activity-dependent mechanisms. Using time-lapse superresolution microscopy in brain slices, we report that axons grow wider after high-frequency AP firing: synaptic boutons undergo a rapid enlargement, which is mostly transient, whereas axon shafts show a more delayed and progressive increase in diameter. Simulations of AP propagation incorporating these morphological dynamics predicted bidirectional effects on AP conduction speed. The predictions were confirmed by electrophysiological experiments, revealing a phase of slowed down AP conduction, which is linked to the transient enlargement of the synaptic boutons, followed by a sustained increase in conduction speed that accompanies the axon shaft widening induced by high-frequency AP firing. Taken together, our study outlines a morphological plasticity mechanism for dynamically fine-tuning AP conduction velocity, which potentially has wide implications for the temporal transfer of information in the brain.
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GSK3β Hyperactivity during an Early Critical Period Impairs Prefrontal Synaptic Plasticity and Induces Lasting Deficits in Spine Morphology and Working Memory. Neuropsychopharmacology 2016; 41:3003-3015. [PMID: 27353310 PMCID: PMC5101547 DOI: 10.1038/npp.2016.110] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 06/16/2016] [Accepted: 06/21/2016] [Indexed: 12/22/2022]
Abstract
Schizophrenia (SZ) is a neurodevelopmental disorder in which the emergence of cognitive symptoms occurs during early adolescence. Glycogen synthase kinase-3β (GSK3β) plays a critical role in synaptic plasticity during development and is highly implicated in the etiology of SZ. However, how GSK3β activity affects synaptic plasticity and working memory function in the prefrontal cortex (PFC) during development remains unknown. Here we show a GSK3β hyperactivity during the early postnatal period in a neurodevelopmental rat SZ model that receives gestational exposure (E17) to the neurotoxin methylazoxymethanol (MAM). Accompanied with this change, adult MAM rats exhibited a significant decrease in spine density as well as impaired working memory, which was rescued by treatment with a GSK3β inhibitor during the juvenile period. Furthermore, the age-dependent hyperactive GSK3β caused a significant deficit in long-term potentiation (LTP) and facilitated long-term depression (LTD) in PFC pyramidal neurons. Notably, these changes in synaptic plasticity occurred only during the late juvenile period and were efficiently reversed by application of GSK3β inhibitors. Because the balance of LTP and LTD plays a critical role in activity-dependent synaptic stabilization and elimination during cortical development, the transient hyperactive GSK3β likely accounts for the cortical spine loss and PFC-dependent cognitive deficits in adulthood. These results highlight the importance of the postnatal trajectory of GSK3β for spine development and PFC function, and may shed light on the prophylactic treatment of cognitive symptoms in the SZ.
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Long-term depression-associated signaling is required for an in vitro model of NMDA receptor-dependent synapse pruning. Neurobiol Learn Mem 2016; 138:39-53. [PMID: 27794462 DOI: 10.1016/j.nlm.2016.10.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 09/20/2016] [Accepted: 10/25/2016] [Indexed: 02/06/2023]
Abstract
Activity-dependent pruning of synaptic contacts plays a critical role in shaping neuronal circuitry in response to the environment during postnatal brain development. Although there is compelling evidence that shrinkage of dendritic spines coincides with synaptic long-term depression (LTD), and that LTD is accompanied by synapse loss, whether NMDA receptor (NMDAR)-dependent LTD is a required step in the progression toward synapse pruning is still unknown. Using repeated applications of NMDA to induce LTD in dissociated rat neuronal cultures, we found that synapse density, as measured by colocalization of fluorescent markers for pre- and postsynaptic structures, was decreased irrespective of the presynaptic marker used, post-treatment recovery time, and the dendritic location of synapses. Consistent with previous studies, we found that synapse loss could occur without apparent net spine loss or cell death. Furthermore, synapse loss was unlikely to require direct contact with microglia, as the number of these cells was minimal in our culture preparations. Supporting a model by which NMDAR-LTD is required for synapse loss, the effect of NMDA on fluorescence colocalization was prevented by phosphatase and caspase inhibitors. In addition, gene transcription and protein translation also appeared to be required for loss of putative synapses. These data support the idea that NMDAR-dependent LTD is a required step in synapse pruning and contribute to our understanding of the basic mechanisms of this developmental process.
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Pérez-Otaño I, Larsen RS, Wesseling JF. Emerging roles of GluN3-containing NMDA receptors in the CNS. Nat Rev Neurosci 2016; 17:623-35. [DOI: 10.1038/nrn.2016.92] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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44
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Jones OD. Do group I metabotropic glutamate receptors mediate LTD? Neurobiol Learn Mem 2016; 138:85-97. [PMID: 27545442 DOI: 10.1016/j.nlm.2016.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/01/2016] [Accepted: 08/17/2016] [Indexed: 01/31/2023]
Abstract
Synapses undergo significant structural and functional reorganization in response to varying patterns of stimulation. These forms of plasticity are considered fundamental to cognition and neuronal homeostasis. An increasing number of reports highlight the importance of activity-dependent synaptic strengthening (long term potentiation: LTP) for learning. However, the functional significance of activity-dependent weakening of synapses (long term depression: LTD) remains relatively poorly understood. One form of synaptic weakening, induced by group I metabotropic glutamate receptors (mGluRs), has received significant attention from a mechanistic point of view and because of its augmentation in a murine model of Fragile X Syndrome. Yet, studies of this form of plasticity often yield confusing, contradictory results. These conflicting findings are likely attributable to the bulk stimulation and recording techniques often used to study synaptic plasticity (typically involving evoked extracellular recordings, which represent the summed activity of many synapses). Such studies inherently blur the identity of the synapses undergoing change, thus giving the illusion that synapses per se are being modified when in fact this may only be true of a specific subset of synapses. Indeed, studies employing minimal synaptic activation paint a fundamentally different picture of what is commonly called "mGluR-LTD". Here, I review the evidence in favour of group I mGluRs as mediators of various forms of synaptic downregulation and attempt to explain discrepancies in the literature. I argue that, while multiple forms of synaptic weakening may be triggered by these receptors, the canonical form of group I mGluR-mediated depression, mGluR-LTD, is in fact not a depression of basal synaptic responses. Rather, it is a reversal of established LTP and thus a form of depotentiation. Far from being arbitrary, this distinction has significant implications for the role of group I mGluRs in cognition, both in the healthy brain and in pathological conditions. Further, the differential actions of group I mGluRs at naïve and potentiated synapses suggest these receptors signal in a state-dependent manner to regulate various stages of the learning process.
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Affiliation(s)
- Owen D Jones
- Department of Psychology, Brain Health Research Centre & Brain Research New Zealand, University of Otago, Dunedin, New Zealand.
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Fauth M, Tetzlaff C. Opposing Effects of Neuronal Activity on Structural Plasticity. Front Neuroanat 2016; 10:75. [PMID: 27445713 PMCID: PMC4923203 DOI: 10.3389/fnana.2016.00075] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 06/16/2016] [Indexed: 12/21/2022] Open
Abstract
The connectivity of the brain is continuously adjusted to new environmental influences by several activity-dependent adaptive processes. The most investigated adaptive mechanism is activity-dependent functional or synaptic plasticity regulating the transmission efficacy of existing synapses. Another important but less prominently discussed adaptive process is structural plasticity, which changes the connectivity by the formation and deletion of synapses. In this review, we show, based on experimental evidence, that structural plasticity can be classified similar to synaptic plasticity into two categories: (i) Hebbian structural plasticity, which leads to an increase (decrease) of the number of synapses during phases of high (low) neuronal activity and (ii) homeostatic structural plasticity, which balances these changes by removing and adding synapses. Furthermore, based on experimental and theoretical insights, we argue that each type of structural plasticity fulfills a different function. While Hebbian structural changes enhance memory lifetime, storage capacity, and memory robustness, homeostatic structural plasticity self-organizes the connectivity of the neural network to assure stability. However, the link between functional synaptic and structural plasticity as well as the detailed interactions between Hebbian and homeostatic structural plasticity are more complex. This implies even richer dynamics requiring further experimental and theoretical investigations.
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Affiliation(s)
- Michael Fauth
- Department of Computational Neuroscience, Third Institute of Physics - Biophysics, Georg-August UniversityGöttingen, Germany; Bernstein Center for Computational NeuroscienceGöttingen, Germany
| | - Christian Tetzlaff
- Bernstein Center for Computational NeuroscienceGöttingen, Germany; Max Planck Institute for Dynamics and Self-OrganizationGöttingen, Germany
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46
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Yang J, Yang H, Liu Y, Li X, Qin L, Lou H, Duan S, Wang H. Astrocytes contribute to synapse elimination via type 2 inositol 1,4,5-trisphosphate receptor-dependent release of ATP. eLife 2016; 5:e15043. [PMID: 27067238 PMCID: PMC4829431 DOI: 10.7554/elife.15043] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 03/15/2016] [Indexed: 01/08/2023] Open
Abstract
Selective elimination of unwanted synapses is vital for the precise formation of neuronal circuits during development, but the underlying mechanisms remain unclear. Using inositol 1,4,5-trisphosphate receptor type 2 knockout (Itpr2−/−) mice to specifically disturb somatic Ca2+ signaling in astrocytes, we showed that developmental elimination of the ventral posteromedial nucleus relay synapse was impaired. Interestingly, intracerebroventricular injection of ATP, but not adenosine, rescued the deficit in synapse elimination in Itpr2−/− mice. Further studies showed that developmental synapse elimination was also impaired in P2ry1−/− mice and was not rescued by ATP, indicating a possible role of purinergic signaling. This hypothesis was confirmed by MRS-2365, a selective P2Y1 agonist, could also rescue the deficient of synapse elimination in Itpr2−/− mice. Our results uncovered a novel mechanism suggesting that astrocytes release ATP in an IP3R2-dependent manner to regulate synapse elimination. DOI:http://dx.doi.org/10.7554/eLife.15043.001 Neighbouring neurons connect to each other and share information through structures known as synapses. As the brain develops, many synapses turn out to be redundant. Just like trees in a garden that need to be trimmed, these redundant synapses must be pruned in order to form the right pattern of connections between different neurons. Brain cells called astrocytes play a key role in synaptic pruning, but it is unclear exactly how astrocytes coordinate this process. One important way in which astrocytes communicate with neurons is through a process called calcium signaling, in which the movement of calcium ions into or out of the cell sets off a cascade of activity inside the astrocytes. Yang et al. have now studied developing mice that lacked a gene that is essential for calcium signaling in astrocytes. Two weeks after they were born, these mice still had redundant synapses that are normally lost after birth. However, injecting the developing brain with a substance called ATP prevented this defect and allowed synapses to be correctly pruned. This is likely to be because astrocytes also use ATP to communicate with neurons, and ATP compensated for the missing calcium signaling. The experiments also uncovered the specific structure – called the P2Y1 receptor – on the outer surface of a neuron that ATP latches on to in order to help remove synapses. Further work is now needed to reveal how activating the P2Y1 receptor coordinates synaptic removal. DOI:http://dx.doi.org/10.7554/eLife.15043.002
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Affiliation(s)
- Junhua Yang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Hongbin Yang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Yali Liu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Xia Li
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Liming Qin
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Huifang Lou
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Shumin Duan
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Hao Wang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
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Seizure-Induced Regulations of Amyloid-β, STEP61, and STEP61 Substrates Involved in Hippocampal Synaptic Plasticity. Neural Plast 2016; 2016:2123748. [PMID: 27127657 PMCID: PMC4835651 DOI: 10.1155/2016/2123748] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 03/08/2016] [Indexed: 12/27/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline. Pathologic accumulation of soluble amyloid-β (Aβ) oligomers impairs synaptic plasticity and causes epileptic seizures, both of which contribute to cognitive dysfunction in AD. However, whether seizures could regulate Aβ-induced synaptic weakening remains unclear. Here we show that a single episode of electroconvulsive seizures (ECS) increased protein expression of membrane-associated STriatal-Enriched protein tyrosine Phosphatase (STEP61) and decreased tyrosine-phosphorylation of its substrates N-methyl D-aspartate receptor (NMDAR) subunit GluN2B and extracellular signal regulated kinase 1/2 (ERK1/2) in the rat hippocampus at 2 days following a single ECS. Interestingly, a significant decrease in ERK1/2 expression and an increase in APP and Aβ levels were observed at 3-4 days following a single ECS when STEP61 level returned to the baseline. Given that pathologic levels of Aβ increase STEP61 activity and STEP61-mediated dephosphorylation of GluN2B and ERK1/2 leads to NMDAR internalization and ERK1/2 inactivation, we propose that upregulation of STEP61 and downregulation of GluN2B and ERK1/2 phosphorylation mediate compensatory weakening of synaptic strength in response to acute enhancement of hippocampal network activity, whereas delayed decrease in ERK1/2 expression and increase in APP and Aβ expression may contribute to the maintenance of this synaptic weakening.
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48
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Emerging Link between Alzheimer's Disease and Homeostatic Synaptic Plasticity. Neural Plast 2016; 2016:7969272. [PMID: 27019755 PMCID: PMC4785275 DOI: 10.1155/2016/7969272] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 01/31/2016] [Indexed: 01/14/2023] Open
Abstract
Alzheimer's disease (AD) is an irreversible brain disorder characterized by progressive cognitive decline and neurodegeneration of brain regions that are crucial for learning and memory. Although intracellular neurofibrillary tangles and extracellular senile plaques, composed of insoluble amyloid-β (Aβ) peptides, have been the hallmarks of postmortem AD brains, memory impairment in early AD correlates better with pathological accumulation of soluble Aβ oligomers and persistent weakening of excitatory synaptic strength, which is demonstrated by inhibition of long-term potentiation, enhancement of long-term depression, and loss of synapses. However, current, approved interventions aiming to reduce Aβ levels have failed to retard disease progression; this has led to a pressing need to identify and target alternative pathogenic mechanisms of AD. Recently, it has been suggested that the disruption of Hebbian synaptic plasticity in AD is due to aberrant metaplasticity, which is a form of homeostatic plasticity that tunes the magnitude and direction of future synaptic plasticity based on previous neuronal or synaptic activity. This review examines emerging evidence for aberrant metaplasticity in AD. Putative mechanisms underlying aberrant metaplasticity in AD will also be discussed. We hope this review inspires future studies to test the extent to which these mechanisms contribute to the etiology of AD and offer therapeutic targets.
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49
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In Sickness and in Health: Perineuronal Nets and Synaptic Plasticity in Psychiatric Disorders. Neural Plast 2015; 2016:9847696. [PMID: 26839720 PMCID: PMC4709762 DOI: 10.1155/2016/9847696] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 09/27/2015] [Indexed: 12/25/2022] Open
Abstract
Rapidly emerging evidence implicates perineuronal nets (PNNs) and extracellular matrix (ECM) molecules that compose or interact with PNNs, in the pathophysiology of several psychiatric disorders. Studies on schizophrenia, autism spectrum disorders, mood disorders, Alzheimer's disease, and epilepsy point to the involvement of ECM molecules such as chondroitin sulfate proteoglycans, Reelin, and matrix metalloproteases, as well as their cell surface receptors. In many of these disorders, PNN abnormalities have also been reported. In the context of the “quadripartite” synapse concept, that is, the functional unit composed of the pre- and postsynaptic terminals, glial processes, and ECM, and of the role that PNNs and ECM molecules play in regulating synaptic functions and plasticity, these findings resonate with one of the most well-replicated aspects of the pathology of psychiatric disorders, that is, synaptic abnormalities. Here we review the evidence for PNN/ECM-related pathology in these disorders, with particular emphasis on schizophrenia, and discuss the hypothesis that such pathology may significantly contribute to synaptic dysfunction.
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50
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Viggiano D, Srivastava DP, Speranza L, Perrone-Capano C, Bellenchi GC, di Porzio U, Buckley NJ. Quantifying barcodes of dendritic spines using entropy-based metrics. Sci Rep 2015; 5:14622. [PMID: 26419702 PMCID: PMC4588562 DOI: 10.1038/srep14622] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/18/2015] [Indexed: 11/09/2022] Open
Abstract
Spine motility analysis has become the mainstay for investigating synaptic plasticity but is limited in its versatility requiring complex, non automatized instrumentations. We describe an entropy-based method for determining the spatial distribution of dendritic spines that allows successful estimation of spine motility from still images. This method has the potential to extend the applicability of spine motility analysis to ex vivo preparations.
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Affiliation(s)
- D Viggiano
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy.,Department of Medicine and Health Sciences, Univ. Molise, Campobasso, 86100, Italy
| | - D P Srivastava
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE5 8AF, United Kingdom.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - L Speranza
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy
| | - C Perrone-Capano
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy.,Department of Pharmacy, University of Naples "Federico II", Naples, 80131, Italy
| | - G C Bellenchi
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy
| | - U di Porzio
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy
| | - N J Buckley
- Department of Psychiatry, University of Oxford, Oxford, OX3 7JX, United Kingdom
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