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Sample records for 3d dendritic spine

  1. Automated 3D dendritic spine detection and analysis from two-photon microscopy

    NASA Astrophysics Data System (ADS)

    Koh, Ingrid Y. Y.; Lindquist, W. Brent

    2001-04-01

    The functional significance of dendritic spines and their plasticity to a wide spectrum of developmental and pathological conditions has led to extensive studies based on spine morphology. The advances in image acquisition techniques and the associated generation of large 3D data sets of optical micrographs have not been accompanied by comparable advances in data analysis techniques. We present an automated 3D spine detection and quantification procedure suitable for images obtained by laser scanning microscopy. The image is first processed by deconvolution and the dendritic phase consisting of the neuronal cytoplasm is extracted by segmentation. Spines are detected as geometrical protrusions relative to the dendritic backbone. As very thin necks may not be imaged, some spine `heads' may be detached from the dendrite and are detected as detached components. These detected heads are merged with spine `bases' where appropriate. Morphological characterizations on spine length, volume, density and shape classifications are obtained. For time-lapse data, images are registered and individual spines are traced through the image sequence. Successful comparison results on spine lengths and densities with manual analysis are obtained. This method is highly automatic and allows detailed and objective quantification of the structure and dynamics of dendritic spines, which can be important predictors for the function of neural networks.

  2. 3-D confocal laser scanning microscopy used in morphometric analysis of rat Purkinje cell dendritic spines after chronic ethanol consumption.

    PubMed

    Wenisch, S; Fortmann, B; Steinmetz, T; Kriete, A; Leiser, R; Bitsch, I

    1998-12-01

    A confocal laser scanning microscope (with a 543 nm laser) was used for imaging rat Purkinje cell dendritic spines at high 3-D resolution. In a nutritionally controlled study of the rat, 5 months of ethanol consumption was demonstrated to alter the spines of Purkinje cell dendrites in rat cerebellum. Intact spines showed significant elongation after ethanol exposure, whereas this neuromorphological alteration could not be detected in controls. Spine elongation could be regarded as compensative growth of spines in search of new synaptic contacts due to alcohol induced cell loss.

  3. A surface-based 3-D dendritic spine detection approach from confocal microscopy images.

    PubMed

    Li, Qing; Deng, Zhigang

    2012-03-01

    Determining the relationship between the dendritic spine morphology and its functional properties is a fundamental challenge in neurobiology research. In particular, how to accurately and automatically analyse meaningful structural information from a large microscopy image data set is far away from being resolved. As pointed out in existing literature, one remaining challenge in spine detection and segmentation is how to automatically separate touching spines. In this paper, based on various global and local geometric features of the dendrite structure, we propose a novel approach to detect and segment neuronal spines, in particular, a breaking-down and stitching-up algorithm to accurately separate touching spines. Extensive performance comparisons show that our approach is more accurate and robust than two state-of-the-art spine detection and segmentation algorithms.

  4. Automated 3-D Detection of Dendritic Spines from In Vivo Two-Photon Image Stacks.

    PubMed

    Singh, P K; Hernandez-Herrera, P; Labate, D; Papadakis, M

    2017-07-14

    Despite the significant advances in the development of automated image analysis algorithms for the detection and extraction of neuronal structures, current software tools still have numerous limitations when it comes to the detection and analysis of dendritic spines. The problem is especially challenging in in vivo imaging, where the difficulty of extracting morphometric properties of spines is compounded by lower image resolution and contrast levels native to two-photon laser microscopy. To address this challenge, we introduce a new computational framework for the automated detection and quantitative analysis of dendritic spines in vivo multi-photon imaging. This framework includes: (i) a novel preprocessing algorithm enhancing spines in a way that they are included in the binarized volume produced during the segmentation of foreground from background; (ii) the mathematical foundation of this algorithm, and (iii) an algorithm for the detection of spine locations in reference to centerline trace and separating them from the branches to whom spines are attached to. This framework enables the computation of a wide range of geometric features such as spine length, spatial distribution and spine volume in a high-throughput fashion. We illustrate our approach for the automated extraction of dendritic spine features in time-series multi-photon images of layer 5 cortical excitatory neurons from the mouse visual cortex.

  5. MDL constrained 3-D grayscale skeletonization algorithm for automated extraction of dendrites and spines from fluorescence confocal images.

    PubMed

    Yuan, Xiaosong; Trachtenberg, Joshua T; Potter, Steve M; Roysam, Badrinath

    2009-12-01

    This paper presents a method for improved automatic delineation of dendrites and spines from three-dimensional (3-D) images of neurons acquired by confocal or multi-photon fluorescence microscopy. The core advance presented here is a direct grayscale skeletonization algorithm that is constrained by a structural complexity penalty using the minimum description length (MDL) principle, and additional neuroanatomy-specific constraints. The 3-D skeleton is extracted directly from the grayscale image data, avoiding errors introduced by image binarization. The MDL method achieves a practical tradeoff between the complexity of the skeleton and its coverage of the fluorescence signal. Additional advances include the use of 3-D spline smoothing of dendrites to improve spine detection, and graph-theoretic algorithms to explore and extract the dendritic structure from the grayscale skeleton using an intensity-weighted minimum spanning tree (IW-MST) algorithm. This algorithm was evaluated on 30 datasets organized in 8 groups from multiple laboratories. Spines were detected with false negative rates less than 10% on most datasets (the average is 7.1%), and the average false positive rate was 11.8%. The software is available in open source form.

  6. FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons

    PubMed Central

    Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M.; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X.; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2015-01-01

    The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3–4 and 8–9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner. PMID:26052271

  7. FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons.

    PubMed

    Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2015-01-01

    The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3-4 and 8-9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner.

  8. An Automated Pipeline for Dendrite Spine Detection and Tracking of 3D Optical Microscopy Neuron Images of In Vivo Mouse Models

    PubMed Central

    Fan, Jing; Zhou, Xiaobo; Dy, Jennifer G.; Zhang, Yong; Wong, Stephen T. C.

    2009-01-01

    The variations in dendritic branch morphology and spine density provide insightful information about the brain function and possible treatment to neurodegenerative disease, for example investigating structural plasticity during the course of Alzheimer's disease. Most automated image processing methods aiming at analyzing these problems are developed for in vitro data. However, in vivo neuron images provide real time information and direct observation of the dynamics of a disease process in a live animal model. This paper presents an automated approach for detecting spines and tracking spine evolution over time with in vivo image data in an animal model of Alzheimer's disease. We propose an automated pipeline starting with curvilinear structure detection to determine the medial axis of the dendritic backbone and spines connected to the backbone. We, then, propose the adaptive local binary fitting (aLBF) energy level set model to accurately locate the boundary of dendritic structures using the central line of curvilinear structure as initialization. To track the growth or loss of spines, we present a maximum likelihood based technique to find the graph homomorphism between two image graph structures at different time points. We employ dynamic programming to search for the optimum solution. The pipeline enables us to extract dynamically changing information from real time in vivo data. We validate our proposed approach by comparing with manual results generated by neurologists. In addition, we discuss the performance of 3D based segmentation and conclude that our method is more accurate in identifying weak spines. Experiments show that our approach can quickly and accurately detect and quantify spines of in vivo neuron images and is able to identify spine elimination and formation. PMID:19434521

  9. A deconvolution method to improve automated 3D-analysis of dendritic spines: application to a mouse model of Huntington's disease.

    PubMed

    Heck, Nicolas; Betuing, Sandrine; Vanhoutte, Peter; Caboche, Jocelyne

    2012-04-01

    Dendritic spines are postsynaptic structures the morphology of which correlates with the strength of synaptic efficacy. Measurements of spine density and spine morphology are achievable using recent imaging and bioinformatics tools. The three-dimensional automated analysis requires optimization of image acquisition and treatment. Here, we studied the critical steps for optimal confocal microscopy imaging of dendritic spines. We characterize the deconvolution process and show that it improves spine morphology analysis. With this method, images of dendritic spines from medium spiny neurons are automatically detected by the software Neuronstudio, which retrieves spine density as well as spine diameter and volume. This approach is illustrated with three-dimensional analysis of dendritic spines in a mouse model of Huntington's disease: the transgenic R6/2 mice. In symptomatic mutant mice, we confirm the decrease in spine density, and the method brings further information and show a decrease in spine volume and dendrite diameter. Moreover, we show a significant decrease in spine density at presymptomatic age which so far has gone unnoticed.

  10. Lipid dynamics at dendritic spines

    PubMed Central

    Dotti, Carlos Gerardo; Esteban, Jose Antonio; Ledesma, María Dolores

    2014-01-01

    Dynamic changes in the structure and composition of the membrane protrusions forming dendritic spines underlie memory and learning processes. In recent years a great effort has been made to characterize in detail the protein machinery that controls spine plasticity. However, we know much less about the involvement of lipids, despite being major membrane components and structure determinants. Moreover, protein complexes that regulate spine plasticity depend on specific interactions with membrane lipids for proper function and accurate intracellular signaling. In this review we gather information available on the lipid composition at dendritic spine membranes and on its dynamics. We pay particular attention to the influence that spine lipid dynamism has on glutamate receptors, which are key regulators of synaptic plasticity. PMID:25152717

  11. Lipid dynamics at dendritic spines.

    PubMed

    Dotti, Carlos Gerardo; Esteban, Jose Antonio; Ledesma, María Dolores

    2014-01-01

    Dynamic changes in the structure and composition of the membrane protrusions forming dendritic spines underlie memory and learning processes. In recent years a great effort has been made to characterize in detail the protein machinery that controls spine plasticity. However, we know much less about the involvement of lipids, despite being major membrane components and structure determinants. Moreover, protein complexes that regulate spine plasticity depend on specific interactions with membrane lipids for proper function and accurate intracellular signaling. In this review we gather information available on the lipid composition at dendritic spine membranes and on its dynamics. We pay particular attention to the influence that spine lipid dynamism has on glutamate receptors, which are key regulators of synaptic plasticity.

  12. Dendritic Spine Pathology in Schizophrenia

    PubMed Central

    Glausier, Jill R.; Lewis, David A.

    2012-01-01

    Schizophrenia is a neurodevelopmental disorder whose clinical features include impairments in perception, cognition and motivation. These impairments reflect alterations in neuronal circuitry within and across multiple brain regions that are due, at least in part, to deficits in dendritic spines, the site of most excitatory synaptic connections. Dendritic spine alterations have been identified in multiple brain regions in schizophrenia, but are best characterized in layer 3 of the neocortex, where pyramidal cell spine density is lower. These spine deficits appear to arise during development, and thus are likely the result of disturbances in the molecular mechanisms that underlie spine formation, pruning, and/or maintenance. Each of these mechanisms may provide insight into novel therapeutic targets for preventing or repairing the alterations in neural circuitry that mediate the debilitating symptoms of schizophrenia. PMID:22546337

  13. Intravital imaging of dendritic spine plasticity

    PubMed Central

    Sau Wan Lai, Cora

    2014-01-01

    Abstract Dendritic spines are the postsynaptic part of most excitatory synapses in the mammalian brain. Recent works have suggested that the structural and functional plasticity of dendritic spines have been associated with information coding and memories. Advances in imaging and labeling techniques enable the study of dendritic spine dynamics in vivo. This perspective focuses on intravital imaging studies of dendritic spine plasticity in the neocortex. I will introduce imaging tools for studying spine dynamics and will further review current findings on spine structure and function under various physiological and pathological conditions. PMID:28243511

  14. Non-synaptic dendritic spines in neocortex.

    PubMed

    Arellano, J I; Espinosa, A; Fairén, A; Yuste, R; DeFelipe, J

    2007-03-16

    A long-held assumption states that each dendritic spine in the cerebral cortex forms a synapse, although this issue has not been systematically investigated. We performed complete ultrastructural reconstructions of a large (n=144) population of identified spines in adult mouse neocortex finding that only 3.6% of the spines clearly lacked synapses. Nonsynaptic spines were small and had no clear head, resembling dendritic filopodia, and could represent a source of new synaptic connections in the adult cerebral cortex.

  15. Dendritic spine dysgenesis in neuropathic pain.

    PubMed

    Tan, Andrew M; Waxman, Stephen G

    2015-08-05

    Neuropathic pain is a significant unmet medical need in patients with variety of injury or disease insults to the nervous system. Neuropathic pain often presents as a painful sensation described as electrical, burning, or tingling. Currently available treatments have limited effectiveness and narrow therapeutic windows for safety. More powerful analgesics, e.g., opioids, carry a high risk for chemical dependence. Thus, a major challenge for pain research is the elucidation of the mechanisms that underlie neuropathic pain and developing targeted strategies to alleviate pathological pain. The mechanistic link between dendritic spine structure and circuit function could explain why neuropathic pain is difficult to treat, since nociceptive processing pathways are adversely "hard-wired" through the reorganization of dendritic spines. Several studies in animal models of neuropathic pain have begun to reveal the functional contribution of dendritic spine dysgenesis in neuropathic pain. Previous reports have demonstrated three primary changes in dendritic spine structure on nociceptive dorsal horn neurons following injury or disease, which accompany chronic intractable pain: (I) increased density of dendritic spines, particularly mature mushroom-spine spines, (II) redistribution of spines toward dendritic branch locations close to the cell body, and (III) enlargement of the spine head diameter, which generally presents as a mushroom-shaped spine. Given the important functional implications of spine distribution, density, and shape for synaptic and neuronal function, the study of dendritic spine abnormality may provide a new perspective for investigating pain, and the identification of specific molecular players that regulate spine morphology may guide the development of more effective and long-lasting therapies.

  16. Amyloid plaque formation precedes dendritic spine loss.

    PubMed

    Bittner, Tobias; Burgold, Steffen; Dorostkar, Mario M; Fuhrmann, Martin; Wegenast-Braun, Bettina M; Schmidt, Boris; Kretzschmar, Hans; Herms, Jochen

    2012-12-01

    Amyloid-beta plaque deposition represents a major neuropathological hallmark of Alzheimer's disease. While numerous studies have described dendritic spine loss in proximity to plaques, much less is known about the kinetics of these processes. In particular, the question as to whether synapse loss precedes or follows plaque formation remains unanswered. To address this question, and to learn more about the underlying kinetics, we simultaneously imaged amyloid plaque deposition and dendritic spine loss by applying two-photon in vivo microscopy through a cranial window in double transgenic APPPS1 mice. As a result, we first observed that the rate of dendritic spine loss in proximity to plaques is the same in both young and aged animals. However, plaque size only increased significantly in the young cohort, indicating that spine loss persists even many months after initial plaque appearance. Tracking the fate of individual spines revealed that net spine loss is caused by increased spine elimination, with the rate of spine formation remaining constant. Imaging of dendritic spines before and during plaque formation demonstrated that spine loss around plaques commences at least 4 weeks after initial plaque formation. In conclusion, spine loss occurs, shortly but with a significant time delay, after the birth of new plaques, and persists in the vicinity of amyloid plaques over many months. These findings hence give further hope to the possibility that there is a therapeutic window between initial amyloid plaque deposition and the onset of structural damage at spines.

  17. Dendritic spine dysgenesis in Autism Related Disorders

    PubMed Central

    Phillips, Mary; Pozzo-Miller, Lucas

    2015-01-01

    The activity-dependent structural and functional plasticity of dendritic spines has led to the long-standing belief that these neuronal compartments are the subcellular sites of learning and memory. Of relevance to human health, central neurons in several neuropsychiatric illnesses, including autism related disorders, have atypical numbers and morphologies of dendritic spines. These so-called dendritic spine dysgeneses found in individuals with autism related disorders are consistently replicated in experimental mouse models. Dendritic spine dysgenesis reflects the underlying synaptopathology that drives clinically relevant behavioral deficits in experimental mouse models, providing a platform for testing new therapeutic approaches. By examining molecular signaling pathways, synaptic deficits, and spine dysgenesis in experimental mouse models of autism related disorders we find strong evidence for mTOR to be a critical point of convergence and promising therapeutic target. PMID:25578949

  18. Intraoperative 3D Computed Tomography: Spine Surgery.

    PubMed

    Adamczak, Stephanie E; Bova, Frank J; Hoh, Daniel J

    2017-10-01

    Spinal instrumentation often involves placing implants without direct visualization of their trajectory or proximity to adjacent neurovascular structures. Two-dimensional fluoroscopy is commonly used to navigate implant placement, but with the advent of computed tomography, followed by the invention of a mobile scanner with an open gantry, three-dimensional (3D) navigation is now widely used. This article critically appraises the available literature to assess the influence of 3D navigation on radiation exposure, accuracy of instrumentation, operative time, and patient outcomes. Also explored is the latest technological advance in 3D neuronavigation: the manufacturing of, via 3D printers, patient-specific templates that direct implant placement. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Ultrastructure of Dendritic Spines: Correlation Between Synaptic and Spine Morphologies

    PubMed Central

    Arellano, Jon I.; Benavides-Piccione, Ruth; DeFelipe, Javier; Yuste, Rafael

    2007-01-01

    Dendritic spines are critical elements of cortical circuits, since they establish most excitatory synapses. Recent studies have reported correlations between morphological and functional parameters of spines. Specifically, the spine head volume is correlated with the area of the postsynaptic density (PSD), the number of postsynaptic receptors and the ready-releasable pool of transmitter, whereas the length of the spine neck is proportional to the degree of biochemical and electrical isolation of the spine from its parent dendrite. Therefore, the morphology of a spine could determine its synaptic strength and learning rules. To better understand the natural variability of neocortical spine morphologies, we used a combination of gold-toned Golgi impregnations and serial thin-section electron microscopy and performed three-dimensional reconstructions of spines from layer 2/3 pyramidal cells from mouse visual cortex. We characterized the structure and synaptic features of 144 completed reconstructed spines, and analyzed their morphologies according to their positions. For all morphological parameters analyzed, spines exhibited a continuum of variability, without clearly distinguishable subtypes of spines or clear dependence of their morphologies on their distance to the soma. On average, the spine head volume was correlated strongly with PSD area and weakly with neck diameter, but not with neck length. The large morphological diversity suggests an equally large variability of synaptic strength and learning rules. PMID:18982124

  20. Dendritic spine dysgenesis in Rett syndrome

    PubMed Central

    Xu, Xin; Miller, Eric C.; Pozzo-Miller, Lucas

    2014-01-01

    Spines are small cytoplasmic extensions of dendrites that form the postsynaptic compartment of the majority of excitatory synapses in the mammalian brain. Alterations in the numerical density, size, and shape of dendritic spines have been correlated with neuronal dysfunction in several neurological and neurodevelopmental disorders associated with intellectual disability, including Rett syndrome (RTT). RTT is a progressive neurodevelopmental disorder associated with intellectual disability that is caused by loss of function mutations in the transcriptional regulator methyl CpG-binding protein 2 (MECP2). Here, we review the evidence demonstrating that principal neurons in RTT individuals and Mecp2-based experimental models exhibit alterations in the number and morphology of dendritic spines. We also discuss the exciting possibility that signaling pathways downstream of brain-derived neurotrophic factor (BDNF), which is transcriptionally regulated by MeCP2, offer promising therapeutic options for modulating dendritic spine development and plasticity in RTT and other MECP2-associated neurodevelopmental disorders. PMID:25309341

  1. Dendritic spine abnormalities in mental retardation.

    PubMed

    von Bohlen Und Halbach, Oliver

    2010-12-01

    Abnormalities in dendritic spine morphologies are often associated with mental retardation. Since dendritic spines are thought to represent a morphological correlate of neuronal plasticity, altered spine morphologies may underlie or contribute to cognitive deficits seen in mental retardation. Signaling cascades that are important for cytoskeletal regulation may have an impact upon spine morphologies. The Rho GTPase signaling pathway has been shown to be involved in the regulation of the cytoskeleton and to play fundamental roles in the structural plasticity of dendritic spines. Moreover, alterations in the Rho GTPase signaling pathway have been shown to contribute to mental retardation. Recently, different mental retardation-associated genes have been identified that encode modulators of the Rho GTPases. Disturbances in these genes can lead to mental retardation and-on the morphological level-to alterations in dendritic spines. Thus, getting more insight into the Rho GTPase signaling pathways, and the molecules involved, would not only help in understanding the basic mechanisms by which the morphologies of dendritic spines are modulated but may also allow the development of therapeutic strategies to counteract some aspects of mental retardation.

  2. Learning rules and persistence of dendritic spines.

    PubMed

    Kasai, Haruo; Hayama, Tatsuya; Ishikawa, Motoko; Watanabe, Satoshi; Yagishita, Sho; Noguchi, Jun

    2010-07-01

    Structural plasticity of dendritic spines underlies learning, memory and cognition in the cerebral cortex. We here summarize fifteen rules of spine structural plasticity, or 'spine learning rules.' Together, they suggest how the spontaneous generation, selection and strengthening (SGSS) of spines represents the physical basis for learning and memory. This SGSS mechanism is consistent with Hebb's learning rule but suggests new relations between synaptic plasticity and memory. We describe the cellular and molecular bases of the spine learning rules, such as the persistence of spine structures and the fundamental role of actin, which polymerizes to form a 'memory gel' required for the selection and strengthening of spine synapses. We also discuss the possible link between transcriptional and translational regulation of structural plasticity. The SGSS mechanism and spine learning rules elucidate the integral nature of synaptic plasticity in neuronal network operations within the actual brain tissue.

  3. Postoperative 3D spine reconstruction by navigating partitioning manifolds

    SciTech Connect

    Kadoury, Samuel; Labelle, Hubert Parent, Stefan

    2016-03-15

    Purpose: The postoperative evaluation of scoliosis patients undergoing corrective treatment is an important task to assess the strategy of the spinal surgery. Using accurate 3D geometric models of the patient’s spine is essential to measure longitudinal changes in the patient’s anatomy. On the other hand, reconstructing the spine in 3D from postoperative radiographs is a challenging problem due to the presence of instrumentation (metallic rods and screws) occluding vertebrae on the spine. Methods: This paper describes the reconstruction problem by searching for the optimal model within a manifold space of articulated spines learned from a training dataset of pathological cases who underwent surgery. The manifold structure is implemented based on a multilevel manifold ensemble to structure the data, incorporating connections between nodes within a single manifold, in addition to connections between different multilevel manifolds, representing subregions with similar characteristics. Results: The reconstruction pipeline was evaluated on x-ray datasets from both preoperative patients and patients with spinal surgery. By comparing the method to ground-truth models, a 3D reconstruction accuracy of 2.24 ± 0.90 mm was obtained from 30 postoperative scoliotic patients, while handling patients with highly deformed spines. Conclusions: This paper illustrates how this manifold model can accurately identify similar spine models by navigating in the low-dimensional space, as well as computing nonlinear charts within local neighborhoods of the embedded space during the testing phase. This technique allows postoperative follow-ups of spinal surgery using personalized 3D spine models and assess surgical strategies for spinal deformities.

  4. Automated curved planar reformation of 3D spine images

    NASA Astrophysics Data System (ADS)

    Vrtovec, Tomaz; Likar, Bostjan; Pernus, Franjo

    2005-10-01

    Traditional techniques for visualizing anatomical structures are based on planar cross-sections from volume images, such as images obtained by computed tomography (CT) or magnetic resonance imaging (MRI). However, planar cross-sections taken in the coordinate system of the 3D image often do not provide sufficient or qualitative enough diagnostic information, because planar cross-sections cannot follow curved anatomical structures (e.g. arteries, colon, spine, etc). Therefore, not all of the important details can be shown simultaneously in any planar cross-section. To overcome this problem, reformatted images in the coordinate system of the inspected structure must be created. This operation is usually referred to as curved planar reformation (CPR). In this paper we propose an automated method for CPR of 3D spine images, which is based on the image transformation from the standard image-based to a novel spine-based coordinate system. The axes of the proposed spine-based coordinate system are determined on the curve that represents the vertebral column, and the rotation of the vertebrae around the spine curve, both of which are described by polynomial models. The optimal polynomial parameters are obtained in an image analysis based optimization framework. The proposed method was qualitatively and quantitatively evaluated on five CT spine images. The method performed well on both normal and pathological cases and was consistent with manually obtained ground truth data. The proposed spine-based CPR benefits from reduced structural complexity in favour of improved feature perception of the spine. The reformatted images are diagnostically valuable and enable easier navigation, manipulation and orientation in 3D space. Moreover, reformatted images may prove useful for segmentation and other image analysis tasks.

  5. The discovery of dendritic spines by Cajal

    PubMed Central

    Yuste, Rafael

    2015-01-01

    Dendritic spines were considered an artifact of the Golgi method until a brash Spanish histologist, Santiago Ramón y Cajal, bet his scientific career arguing that they were indeed real, correctly deducing their key role in mediating synaptic connectivity. This article reviews the historical context of the discovery of spines and the reasons behind Cajal's obsession with them, all the way till his deathbed. PMID:25954162

  6. The spine problem: finding a function for dendritic spines.

    PubMed

    Malanowski, Sarah; Craver, Carl F

    2014-01-01

    Why do neurons have dendritic spines? This question-the heart of what Yuste calls "the spine problem"-presupposes that why-questions of this sort have scientific answers: that empirical findings can favor or count against claims about why neurons have spines. Here we show how such questions can receive empirical answers. We construe such why-questions as questions about how spines make a difference to the behavior of some mechanism that we take to be significant. Why-questions are driven fundamentally by the effort to understand how some item, such as the dendritic spine, is situated in the causal structure of the world (the causal nexus). They ask for a filter on that busy world that allows us to see a part's individual contribution to a mechanism, independent of everything else going on. So understood, answers to why-questions can be assessed by testing the claims these answers make about the causal structure of a mechanism. We distinguish four ways of making a difference to a mechanism (necessary, modulatory, component, background condition), and we sketch their evidential requirements. One consequence of our analysis is that there are many spine problems and that any given spine problem might have many acceptable answers.

  7. Three-dimensional spatial modeling of spines along dendritic networks in human cortical pyramidal neurons

    PubMed Central

    Larrañaga, Pedro; Benavides-Piccione, Ruth; Fernaud-Espinosa, Isabel; DeFelipe, Javier; Bielza, Concha

    2017-01-01

    We modeled spine distribution along the dendritic networks of pyramidal neurons in both basal and apical dendrites. To do this, we applied network spatial analysis because spines can only lie on the dendritic shaft. We expanded the existing 2D computational techniques for spatial analysis along networks to perform a 3D network spatial analysis. We analyzed five detailed reconstructions of adult human pyramidal neurons of the temporal cortex with a total of more than 32,000 spines. We confirmed that there is a spatial variation in spine density that is dependent on the distance to the cell body in all dendrites. Considering the dendritic arborizations of each pyramidal cell as a group of instances of the same observation (the neuron), we used replicated point patterns together with network spatial analysis for the first time to search for significant differences in the spine distribution of basal dendrites between different cells and between all the basal and apical dendrites. To do this, we used a recent variant of Ripley’s K function defined to work along networks. The results showed that there were no significant differences in spine distribution along basal arbors of the same neuron and along basal arbors of different pyramidal neurons. This suggests that dendritic spine distribution in basal dendritic arbors adheres to common rules. However, we did find significant differences in spine distribution along basal versus apical networks. Therefore, not only do apical and basal dendritic arborizations have distinct morphologies but they also obey different rules of spine distribution. Specifically, the results suggested that spines are more clustered along apical than in basal dendrites. Collectively, the results further highlighted that synaptic input information processing is different between these two dendritic domains. PMID:28662210

  8. Three-dimensional spatial modeling of spines along dendritic networks in human cortical pyramidal neurons.

    PubMed

    Anton-Sanchez, Laura; Larrañaga, Pedro; Benavides-Piccione, Ruth; Fernaud-Espinosa, Isabel; DeFelipe, Javier; Bielza, Concha

    2017-01-01

    We modeled spine distribution along the dendritic networks of pyramidal neurons in both basal and apical dendrites. To do this, we applied network spatial analysis because spines can only lie on the dendritic shaft. We expanded the existing 2D computational techniques for spatial analysis along networks to perform a 3D network spatial analysis. We analyzed five detailed reconstructions of adult human pyramidal neurons of the temporal cortex with a total of more than 32,000 spines. We confirmed that there is a spatial variation in spine density that is dependent on the distance to the cell body in all dendrites. Considering the dendritic arborizations of each pyramidal cell as a group of instances of the same observation (the neuron), we used replicated point patterns together with network spatial analysis for the first time to search for significant differences in the spine distribution of basal dendrites between different cells and between all the basal and apical dendrites. To do this, we used a recent variant of Ripley's K function defined to work along networks. The results showed that there were no significant differences in spine distribution along basal arbors of the same neuron and along basal arbors of different pyramidal neurons. This suggests that dendritic spine distribution in basal dendritic arbors adheres to common rules. However, we did find significant differences in spine distribution along basal versus apical networks. Therefore, not only do apical and basal dendritic arborizations have distinct morphologies but they also obey different rules of spine distribution. Specifically, the results suggested that spines are more clustered along apical than in basal dendrites. Collectively, the results further highlighted that synaptic input information processing is different between these two dendritic domains.

  9. 3-D Display Of Magnetic Resonance Imaging Of The Spine

    NASA Astrophysics Data System (ADS)

    Nelson, Alan C.; Kim, Yongmin; Haralick, Robert M.; Anderson, Paul A.; Johnson, Roger H.; DeSoto, Larry A.

    1988-06-01

    The original data is produced through standard magnetic resonance imaging (MRI) procedures with a surface coil applied to the lower back of a normal human subject. The 3-D spine image data consists of twenty-six contiguous slices with 256 x 256 pixels per slice. Two methods for visualization of the 3-D spine are explored. One method utilizes a verifocal mirror system which creates a true 3-D virtual picture of the object. Another method uses a standard high resolution monitor to simultaneously show the three orthogonal sections which intersect at any user-selected point within the object volume. We discuss the application of these systems in assessment of low back pain.

  10. Automated 4D analysis of dendritic spine morphology: applications to stimulus-induced spine remodeling and pharmacological rescue in a disease model.

    PubMed

    Swanger, Sharon A; Yao, Xiaodi; Gross, Christina; Bassell, Gary J

    2011-10-07

    Uncovering the mechanisms that regulate dendritic spine morphology has been limited, in part, by the lack of efficient and unbiased methods for analyzing spines. Here, we describe an automated 3D spine morphometry method and its application to spine remodeling in live neurons and spine abnormalities in a disease model. We anticipate that this approach will advance studies of synapse structure and function in brain development, plasticity, and disease.

  11. Diffusion in a dendritic spine: The role of geometry

    NASA Astrophysics Data System (ADS)

    Biess, A.; Korkotian, E.; Holcman, D.

    2007-08-01

    Dendritic spines, the sites where excitatory synapses are made in most neurons, can dynamically regulate diffusing molecules by changing their shape. We present here a combination of theory, simulations, and experiments to quantify the diffusion time course in dendritic spines. We derive analytical formulas and compared them to Brownian simulations for the mean sojourn time a diffusing molecule stays inside a dendritic spine when either the molecule can reenter the spine head or not, once it is located in the spine neck. We show that the spine length is the fundamental regulatory geometrical parameter for the diffusion decay rate in the neck only. By changing the spine length, dendritic spines can be dynamically coupled or uncoupled to their parent dendrites, which regulates diffusion, and this property makes them unique structures, different from static dendrites.

  12. Levodopa treatment and dendritic spine pathology.

    PubMed

    Nishijima, Haruo; Ueno, Tatsuya; Funamizu, Yukihisa; Ueno, Shinya; Tomiyama, Masahiko

    2017-09-07

    Parkinson's disease (PD) is a neurodegenerative disorder associated with the progressive loss of nigrostriatal dopaminergic neurons. Levodopa is the most effective treatment for the motor symptoms of PD. However, chronic oral levodopa treatment can lead to various motor and nonmotor complications because of nonphysiological pulsatile dopaminergic stimulation in the brain. Examinations of autopsy cases with PD have revealed a decreased number of dendritic spines of striatal neurons. Animal models of PD have revealed altered density and morphology of dendritic spines of neurons in various brain regions after dopaminergic denervation or dopaminergic denervation plus levodopa treatment, indicating altered synaptic transmission. Recent studies using rodent models have reported dendritic spine head enlargement in the caudate-putamen, nucleus accumbens, primary motor cortex, and prefrontal cortex in cases where chronic levodopa treatment following dopaminergic denervation induced dyskinesia-like abnormal involuntary movement. Hypertrophy of spines results from insertion of alpha-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropanoic acid receptors into the postsynaptic membrane. Such spine enlargement indicates hypersensitivity of the synapse to excitatory inputs and is compatible with a lack of depotentiation, which is an electrophysiological hallmark of levodopa-induced dyskinesia found in the corticostriatal synapses of dyskinetic animals and the motor cortex of dyskinetic PD patients. This synaptic plasticity may be one of the mechanisms underlying the priming of levodopa-induced complications such as levodopa-induced dyskinesia and dopamine dysregulation syndrome. Drugs that could potentially prevent spine enlargement, such as calcium channel blockers, N-methyl-D-aspartate receptor antagonists, alpha-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropanoic acid receptor antagonists, and metabotropic glutamate receptor antagonists, are candidates for treatment of levodopa

  13. Random Positions of Dendritic Spines in Human Cerebral Cortex

    PubMed Central

    Morales, Juan; Benavides-Piccione, Ruth; Dar, Mor; Fernaud, Isabel; Rodríguez, Angel; Anton-Sanchez, Laura; Bielza, Concha; Larrañaga, Pedro; DeFelipe, Javier

    2014-01-01

    Dendritic spines establish most excitatory synapses in the brain and are located in Purkinje cell's dendrites along helical paths, perhaps maximizing the probability to contact different axons. To test whether spine helixes also occur in neocortex, we reconstructed >500 dendritic segments from adult human cortex obtained from autopsies. With Fourier analysis and spatial statistics, we analyzed spine position along apical and basal dendrites of layer 3 pyramidal neurons from frontal, temporal, and cingulate cortex. Although we occasionally detected helical positioning, for the great majority of dendrites we could not reject the null hypothesis of spatial randomness in spine locations, either in apical or basal dendrites, in neurons of different cortical areas or among spines of different volumes and lengths. We conclude that in adult human neocortex spine positions are mostly random. We discuss the relevance of these results for spine formation and plasticity and their functional impact for cortical circuits. PMID:25057209

  14. Synaptic amplification by dendritic spines enhances input cooperativity.

    PubMed

    Harnett, Mark T; Makara, Judit K; Spruston, Nelson; Kath, William L; Magee, Jeffrey C

    2012-11-22

    Dendritic spines are the nearly ubiquitous site of excitatory synaptic input onto neurons and as such are critically positioned to influence diverse aspects of neuronal signalling. Decades of theoretical studies have proposed that spines may function as highly effective and modifiable chemical and electrical compartments that regulate synaptic efficacy, integration and plasticity. Experimental studies have confirmed activity-dependent structural dynamics and biochemical compartmentalization by spines. However, there is a longstanding debate over the influence of spines on the electrical aspects of synaptic transmission and dendritic operation. Here we measure the amplitude ratio of spine head to parent dendrite voltage across a range of dendritic compartments and calculate the associated spine neck resistance (R(neck)) for spines at apical trunk dendrites in rat hippocampal CA1 pyramidal neurons. We find that R(neck) is large enough (~500 MΩ) to amplify substantially the spine head depolarization associated with a unitary synaptic input by ~1.5- to ~45-fold, depending on parent dendritic impedance. A morphologically realistic compartmental model capable of reproducing the observed spatial profile of the amplitude ratio indicates that spines provide a consistently high-impedance input structure throughout the dendritic arborization. Finally, we demonstrate that the amplification produced by spines encourages electrical interaction among coactive inputs through an R(neck)-dependent increase in spine head voltage-gated conductance activation. We conclude that the electrical properties of spines promote nonlinear dendritic processing and associated forms of plasticity and storage, thus fundamentally enhancing the computational capabilities of neurons.

  15. Age-Based Comparison of Human Dendritic Spine Structure Using Complete Three-Dimensional Reconstructions

    PubMed Central

    Benavides-Piccione, Ruth; Fernaud-Espinosa, Isabel; Robles, Victor; Yuste, Rafael; DeFelipe, Javier

    2013-01-01

    Dendritic spines of pyramidal neurons are targets of most excitatory synapses in the cerebral cortex. Recent evidence suggests that the morphology of the dendritic spine could determine its synaptic strength and learning rules. However, unfortunately, there are scant data available regarding the detailed morphology of these structures for the human cerebral cortex. In the present study, we analyzed over 8900 individual dendritic spines that were completely 3D reconstructed along the length of apical and basal dendrites of layer III pyramidal neurons in the cingulate cortex of 2 male humans (aged 40 and 85 years old), using intracellular injections of Lucifer Yellow in fixed tissue. We assembled a large, quantitative database, which revealed a major reduction in spine densities in the aged case. Specifically, small and short spines of basal dendrites and long spines of apical dendrites were lost, regardless of the distance from the soma. Given the age difference between the cases, our results suggest selective alterations in spines with aging in humans and indicate that the spine volume and length are regulated by different biological mechanisms. PMID:22710613

  16. ROCK1 and ROCK2 inhibition alters dendritic spine morphology in hippocampal neurons.

    PubMed

    Swanger, Sharon A; Mattheyses, Alexa L; Gentry, Erik G; Herskowitz, Jeremy H

    2015-01-01

    Communication among neurons is mediated through synaptic connections between axons and dendrites, and most excitatory synapses occur on actin-rich protrusions along dendrites called dendritic spines. Dendritic spines are structurally dynamic, and synapse strength is closely correlated with spine morphology. Abnormalities in the size, shape, and number of dendritic spines are prevalent in neurologic diseases, including autism spectrum disorders, schizophrenia, and Alzheimer disease. However, therapeutic targets that influence spine morphology are lacking. Rho-associated coiled-coil containing protein kinases (ROCK) 1 and ROCK2 are potent regulators of the actin cytoskeleton and highly promising drug targets for central nervous system disorders. In this report, we addressed how pharmacologic inhibition of ROCK1 and ROCK2 affects dendritic spine morphology. Hippocampal neurons were transfected with plasmids expressing fluorescently labeled Lifeact, a small actin binding peptide, and then incubated with or without Y-27632, an established pan-ROCK small molecule inhibitor. Using an automated 3D spine morphometry analysis method, we showed that inhibition of ROCK1 and ROCK2 significantly increased the mean protrusion density and significantly reduced the mean protrusion width. A trending increase in mean protrusion length was observed following Y-27632 treatment, and novel effects were observed among spine classes. Exposure to Y-27632 significantly increased the number of filopodia and thin spines, while the numbers of stubby and mushroom spines were similar to mock-treated samples. These findings support the hypothesis that pharmacologic inhibition of ROCK1 and ROCK2 may convey therapeutic benefit for neurologic disorders that feature dendritic spine loss or aberrant structural plasticity.

  17. Astrocytes refine cortical connectivity at dendritic spines

    PubMed Central

    Risher, W Christopher; Patel, Sagar; Kim, Il Hwan; Uezu, Akiyoshi; Bhagat, Srishti; Wilton, Daniel K; Pilaz, Louis-Jan; Singh Alvarado, Jonnathan; Calhan, Osman Y; Silver, Debra L; Stevens, Beth; Calakos, Nicole; Soderling, Scott H; Eroglu, Cagla

    2014-01-01

    During cortical synaptic development, thalamic axons must establish synaptic connections despite the presence of the more abundant intracortical projections. How thalamocortical synapses are formed and maintained in this competitive environment is unknown. Here, we show that astrocyte-secreted protein hevin is required for normal thalamocortical synaptic connectivity in the mouse cortex. Absence of hevin results in a profound, long-lasting reduction in thalamocortical synapses accompanied by a transient increase in intracortical excitatory connections. Three-dimensional reconstructions of cortical neurons from serial section electron microscopy (ssEM) revealed that, during early postnatal development, dendritic spines often receive multiple excitatory inputs. Immuno-EM and confocal analyses revealed that majority of the spines with multiple excitatory contacts (SMECs) receive simultaneous thalamic and cortical inputs. Proportion of SMECs diminishes as the brain develops, but SMECs remain abundant in Hevin-null mice. These findings reveal that, through secretion of hevin, astrocytes control an important developmental synaptic refinement process at dendritic spines. DOI: http://dx.doi.org/10.7554/eLife.04047.001 PMID:25517933

  18. Imaging dendritic spines of rat primary hippocampal neurons using structured illumination microscopy.

    PubMed

    Schouten, Marijn; De Luca, Giulia M R; Alatriste González, Diana K; de Jong, Babette E; Timmermans, Wendy; Xiong, Hui; Krugers, Harm; Manders, Erik M M; Fitzsimons, Carlos P

    2014-05-04

    protocol, dendritic spines can be reconstructed in 3D from series of SIM image stacks using specialized software.

  19. Dendritic spine actin dynamics in neuronal maturation and synaptic plasticity.

    PubMed

    Hlushchenko, Iryna; Koskinen, Mikko; Hotulainen, Pirta

    2016-09-01

    The majority of the postsynaptic terminals of excitatory synapses in the central nervous system exist on small bulbous structures on dendrites known as dendritic spines. The actin cytoskeleton is a structural element underlying the proper development and morphology of dendritic spines. Synaptic activity patterns rapidly change actin dynamics, leading to morphological changes in dendritic spines. In this mini-review, we will discuss recent findings on neuronal maturation and synaptic plasticity-induced changes in the dendritic spine actin cytoskeleton. We propose that actin dynamics in dendritic spines decrease through actin filament crosslinking during neuronal maturation. In long-term potentiation, we evaluate the model of fast breakdown of actin filaments through severing and rebuilding through polymerization and later stabilization through crosslinking. We will discuss the role of Ca(2+) in long-term depression, and suggest that actin filaments are dissolved through actin filament severing. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  20. Anomalous diffusion in Purkinje cell dendrites caused by spines

    PubMed Central

    Santamaria, Fidel; Wils, Stefan; De Schutter, Erik; Augustine, George J.

    2007-01-01

    We combined local photolysis of caged compounds with fluorescence imaging to visualize molecular diffusion within dendrites of cerebellar Purkinje cells. Diffusion of a volume marker, fluorescein dextran, within spiny dendrites was remarkably slow in comparison to its diffusion in smooth dendrites. Computer simulations indicate that this retardation is due to a transient trapping of molecules within dendritic spines, yielding anomalous diffusion. We considered the influence of spine trapping on the diffusion of calcium ions (Ca2+) and inositol-1,4,5-triphospate (IP3), two synaptic second messengers. Diffusion of IP3 was strongly influenced by the presence of dendritic spines while Ca2+ was removed so rapidly that it could not diffuse far enough to be trapped. We conclude that an important function of dendritic spines may be to trap chemical signals and thereby create slowed anomalous diffusion within dendrites. PMID:17114048

  1. Organization of TNIK in dendritic spines.

    PubMed

    Burette, Alain C; Phend, Kristen D; Burette, Susan; Lin, Qingcong; Liang, Musen; Foltz, Gretchen; Taylor, Noël; Wang, Qi; Brandon, Nicholas J; Bates, Brian; Ehlers, Michael D; Weinberg, Richard J

    2015-09-01

    Tumor necrosis factor receptor-associated factor 2 (TRAF2)- and noncatalytic region of tyrosine kinase (NCK)-interacting kinase (TNIK) has been identified as an interactor in the psychiatric risk factor, Disrupted in Schizophrenia 1 (DISC1). As a step toward deciphering its function in the brain, we performed high-resolution light and electron microscopic immunocytochemistry. We demonstrate here that TNIK is expressed in neurons throughout the adult mouse brain. In striatum and cerebral cortex, TNIK concentrates in dendritic spines, especially in the vicinity of the lateral edge of the synapse. Thus, TNIK is highly enriched at a microdomain critical for glutamatergic signaling.

  2. Rat-strain dependent changes of dendritic and spine morphology in the hippocampus after cocaine self-administration.

    PubMed

    Selvas, Abraham; Coria, Santiago M; Kastanauskaite, Asta; Fernaud-Espinosa, Isabel; DeFelipe, Javier; Ambrosio, Emilio; Miguéns, Miguel

    2017-01-01

    We previously showed that cocaine self-administration increases spine density in CA1 hippocampal neurons in Lewis (LEW) but not in Fischer 344 (F344) rats. Dendritic spine morphology is intimately related to its function. Thus, we conducted a 3D morphological analysis of CA1 dendrites and dendritic spines in these two strains of rats. Strain-specific differences were observed prior to cocaine self-administration: LEW rats had significantly larger dendritic diameters but lower spine density than the F344 strain. After cocaine self-administration, proximal dendritic volume, dendritic surface area and spine density were increased in LEW rats, where a higher percentage of larger spines were also observed. In addition, we found a strong positive correlation between dendritic volume and spine morphology, and a moderate correlation between dendritic volume and spine density in cocaine self-administered LEW rats, an effect that was not evident in any other condition. By contrast, after cocaine self-administration, F334 rats showed decreased spine head volumes. Our findings suggest that genetic differences could play a key role in the structural plasticity induced by cocaine in CA1 pyramidal neurons. These cocaine-induced alterations could be related to differences in the memory processing of drug reward cues that could potentially explain differential individual vulnerability to cocaine addiction. © 2015 Society for the Study of Addiction.

  3. Dendritic spine pathology and thrombospondin-1 deficits in Down syndrome.

    PubMed

    Torres, Maria D; Garcia, Octavio; Tang, Cindy; Busciglio, Jorge

    2017-09-28

    Abnormal dendritic spine structure and function is one of the most prominent features associated with neurodevelopmental disorders including Down syndrome (DS). Defects in both spine morphology and spine density may underlie alterations in neuronal and synaptic plasticity, ultimately affecting cognitive ability. Here we briefly examine the role of astrocytes in spine alterations and more specifically the involvement of astrocyte-secreted thrombospondin 1 (TSP-1) deficits in spine and synaptic pathology in DS. Copyright © 2017. Published by Elsevier Inc.

  4. Studies on the 3-dimensional architecture of dendritic spines and varicosities in human cortex by confocal laser scanning microscopy and Lucifer yellow microinjections.

    PubMed

    Belichenko, P V; Dahlström, A

    1995-03-01

    A method for 3-dimensional (3-D) visualization of dendritic spines and varicosities in human cortical neurons is described. Intracellular microinjection of Lucifer Yellow was used to display the morphology of dendrites on pyramidal and non-pyramidal neurons. Confocal laser scanning microscopy was used for imaging, and 3-D reconstructions and analysis of spines and varicosities were performed. The frontal, temporal, parietal and occipital cortices, and hippocampus in normal and pathological human brains were studied. Using this technique spines can be visualized from both sides of dendrites, which are 'hidden' in 2-D representations, and therefore not usually included in the extimation of dendritic spine density/total spine numbers. In patients with Rett's syndrome and some epilepsy patients, a regional loss of dendritic spines ('naked' dendrites) was found. These results will be included in the Human Brain Mapping Project.

  5. Cold-induced exodus of postsynaptic proteins from dendritic spines.

    PubMed

    Cheng, Hui-Hsuan; Huang, Zu-Han; Lin, Wei-Hsiang; Chow, Wei-Yuan; Chang, Yen-Chung

    2009-02-01

    Dendritic spines are small protrusions on neuronal dendrites and the major target of the excitatory inputs in mammalian brains. Cultured neurons and brain slices are important tools in studying the biochemical and cellular properties of dendritic spines. During the processes of immunocytochemical studies of neurons and the preparation of brain slices, neurons were often kept at temperatures lower than 37 degrees C for varied lengths of time. This study sought to investigate whether and how cold treatment would affect the protein composition of dendritic spines. The results indicated that upon cold treatment four postsynaptic proteins, namely, alpha,beta-tubulins, calcium, calmodulin-dependent protein kinase IIalpha, and cytoplasmic dynein heavy chain and microtubule-associated protein 2, but not PSD-95 or AMPA receptors, exited from the majority of dendritic spines of cultured rat hippocampal neurons in a Gd(3+)-sensitive manner. The cold-induced exit of tubulins from dendritic spines was further found to be an energy-dependent process involving the activation of Gd(3+)-sensitive calcium channels and ryanodine receptors. The results thus indicate that changes in temperature, calcium concentration, and energy supply of the medium surrounding neurons would affect the protein composition of the dendritic spines and conceivably the protein composition of the subcellular organizations, such as the postsynaptic density, in the cytoplasm of dendritic spines.

  6. Synaptic amplification by dendritic spines enhances input cooperativity

    PubMed Central

    Harnett, Mark T.; Makara, Judit K.; Spruston, Nelson; Kath, William L.; Magee, Jeffrey C.

    2012-01-01

    Dendritic spines are the nearly ubiquitous site of excitatory synaptic input onto neurons1–2 and as such are critically positioned to influence diverse aspects of neuronal signaling. Decades of theoretical studies have proposed that spines may function as highly effective and modifiable chemical and electrical compartments that regulate synaptic efficacy, integration, and plasticity3–8. Experimental studies have confirmed activity-dependent structural dynamics and biochemical compartmentalization by spines9–12. However, a longstanding debate remains over the influence of spines on the electrical aspects of synaptic transmission and dendritic operation3–8,13–18. Here, we measured the amplitude ratio (AR) of spine head to parent dendrite voltage across a range of dendritic compartments and calculated the associated Rneck for spines at apical trunk dendrites in hippocampal CA1 pyramidal neurons. We found that Rneck is large enough (~500 MΩ) to substantially amplify the spine head depolarization associated with a unitary synaptic input by ~1.5- to ~45-fold depending on parent dendritic impedance. A morphologically realistic compartmental model capable of reproducing the observed spatial profile of AR indicates that spines provide a consistently high impedance input structure throughout the dendritic arbor. Finally, we demonstrate that the amplification produced by spines encourages electrical interaction among coactive inputs through an Rneck-dependent increase in spine head voltage- dependent conductance activation. We conclude that the electrical properties of spines promote nonlinear dendritic processing and associated forms of plasticity and storage, thus fundamentally enhancing the computational capabilities of neurons19–21. PMID:23103868

  7. Castration alters the number and structure of dendritic spines in the male posterodorsal medial amygdala.

    PubMed

    Zancan, Mariana; Dall'Oglio, Aline; Quagliotto, Edson; Rasia-Filho, Alberto A

    2017-02-01

    The posterodorsal medial amygdala (MePD) is responsive to androgens and participates in the integration of olfactory/vomeronasal stimuli for the display of sexual behavior in rats. Adult gonadectomy (GDX) affects the MePD structural integrity at the same time that impairs male mating behavior. At the cellular level, dendritic spines modulate excitatory synaptic transmission, strength, and plasticity. Here, we describe the effect of GDX on the number and shape of dendritic spines in the right and left MePD using confocal microscopy and 3D image reconstruction. Age-matched adult rats were intact (n = 6), submitted to a sham procedure (n = 4) or castrated and studied 90 days after GDX (n = 5). The MePD neurons have a density of 1.1 spines/dendritic μm composed of thin, mushroom-like, stubby/wide, and few ramified or atypical spines. Irrespective of brain hemisphere, GDX decreased the dendritic spine density in the MePD, but induced different effects on each spine type. That is, compared to control groups, GDX reduced (i) the number (up to 50%) of thin, mushroom-like, and ramified spines, and (ii) the size and the neck length of thin spines as well as the head diameter of ramified spines. Besides, GDX increased the number of stubby/wide and atypical spines (up to 140% and 400%, respectively). These data show that GDX promotes a cellular and synaptic reorganization in a spine-specific manner in the MePD. By altering the number and shape of these connectional elements, GDX can affect the neural transmission and hinder the function of integrated brain circuitries in the male brain.

  8. Dendritic spine geometry can localize GTPase signaling in neurons

    PubMed Central

    Ramirez, Samuel A.; Raghavachari, Sridhar; Lew, Daniel J.

    2015-01-01

    Dendritic spines are the postsynaptic terminals of most excitatory synapses in the mammalian brain. Learning and memory are associated with long-lasting structural remodeling of dendritic spines through an actin-mediated process regulated by the Rho-family GTPases RhoA, Rac, and Cdc42. These GTPases undergo sustained activation after synaptic stimulation, but whereas Rho activity can spread from the stimulated spine, Cdc42 activity remains localized to the stimulated spine. Because Cdc42 itself diffuses rapidly in and out of the spine, the basis for the retention of Cdc42 activity in the stimulated spine long after synaptic stimulation has ceased is unclear. Here we model the spread of Cdc42 activation at dendritic spines by means of reaction-diffusion equations solved on spine-like geometries. Excitable behavior arising from positive feedback in Cdc42 activation leads to spreading waves of Cdc42 activity. However, because of the very narrow neck of the dendritic spine, wave propagation is halted through a phenomenon we term geometrical wave-pinning. We show that this can account for the localization of Cdc42 activity in the stimulated spine, and, of interest, retention is enhanced by high diffusivity of Cdc42. Our findings are broadly applicable to other instances of signaling in extreme geometries, including filopodia and primary cilia. PMID:26337387

  9. Random positions of dendritic spines in human cerebral cortex.

    PubMed

    Morales, Juan; Benavides-Piccione, Ruth; Dar, Mor; Fernaud, Isabel; Rodríguez, Angel; Anton-Sanchez, Laura; Bielza, Concha; Larrañaga, Pedro; DeFelipe, Javier; Yuste, Rafael

    2014-07-23

    Dendritic spines establish most excitatory synapses in the brain and are located in Purkinje cell's dendrites along helical paths, perhaps maximizing the probability to contact different axons. To test whether spine helixes also occur in neocortex, we reconstructed >500 dendritic segments from adult human cortex obtained from autopsies. With Fourier analysis and spatial statistics, we analyzed spine position along apical and basal dendrites of layer 3 pyramidal neurons from frontal, temporal, and cingulate cortex. Although we occasionally detected helical positioning, for the great majority of dendrites we could not reject the null hypothesis of spatial randomness in spine locations, either in apical or basal dendrites, in neurons of different cortical areas or among spines of different volumes and lengths. We conclude that in adult human neocortex spine positions are mostly random. We discuss the relevance of these results for spine formation and plasticity and their functional impact for cortical circuits. Copyright © 2014 the authors 0270-6474/14/3410078-07$15.00/0.

  10. Musical representation of dendritic spine distribution: a new exploratory tool.

    PubMed

    Toharia, Pablo; Morales, Juan; de Juan, Octavio; Fernaud, Isabel; Rodríguez, Angel; DeFelipe, Javier

    2014-04-01

    Dendritic spines are small protrusions along the dendrites of many types of neurons in the central nervous system and represent the major target of excitatory synapses. For this reason, numerous anatomical, physiological and computational studies have focused on these structures. In the cerebral cortex the most abundant and characteristic neuronal type are pyramidal cells (about 85 % of all neurons) and their dendritic spines are the main postsynaptic target of excitatory glutamatergic synapses. Thus, our understanding of the synaptic organization of the cerebral cortex largely depends on the knowledge regarding synaptic inputs to dendritic spines of pyramidal cells. Much of the structural data on dendritic spines produced by modern neuroscience involves the quantitative analysis of image stacks from light and electron microscopy, using standard statistical and mathematical tools and software developed to this end. Here, we present a new method with musical feedback for exploring dendritic spine morphology and distribution patterns in pyramidal neurons. We demonstrate that audio analysis of spiny dendrites with apparently similar morphology may "sound" quite different, revealing anatomical substrates that are not apparent from simple visual inspection. These morphological/music translations may serve as a guide for further mathematical analysis of the design of the pyramidal neurons and of spiny dendrites in general.

  11. Dendritic Spines as Tunable Regulators of Synaptic Signals

    PubMed Central

    Tønnesen, Jan; Nägerl, U. Valentin

    2016-01-01

    Neurons are perpetually receiving vast amounts of information in the form of synaptic input from surrounding cells. The majority of input occurs at thousands of dendritic spines, which mediate excitatory synaptic transmission in the brain, and is integrated by the dendritic and somatic compartments of the postsynaptic neuron. The functional role of dendritic spines in shaping biochemical and electrical signals transmitted via synapses has long been intensely studied. Yet, many basic questions remain unanswered, in particular regarding the impact of their nanoscale morphology on electrical signals. Here, we review our current understanding of the structure and function relationship of dendritic spines, focusing on the controversy of electrical compartmentalization and the potential role of spine structural changes in synaptic plasticity. PMID:27340393

  12. Electrical behaviour of dendritic spines as revealed by voltage imaging

    PubMed Central

    Popovic, Marko A.; Carnevale, Nicholas; Rozsa, Balazs; Zecevic, Dejan

    2015-01-01

    Thousands of dendritic spines on individual neurons process information and mediate plasticity by generating electrical input signals using a sophisticated assembly of transmitter receptors and voltage-sensitive ion channel molecules. Our understanding, however, of the electrical behaviour of spines is limited because it has not been possible to record input signals from these structures with adequate sensitivity and spatiotemporal resolution. Current interpretation of indirect data and speculations based on theoretical considerations are inconclusive. Here we use an electrochromic voltage-sensitive dye which acts as a transmembrane optical voltmeter with a linear scale to directly monitor electrical signals from individual spines on thin basal dendrites. The results show that synapses on these spines are not electrically isolated by the spine neck to a significant extent. Electrically, they behave as if they are located directly on dendrites. PMID:26436431

  13. Input transformation by dendritic spines of pyramidal neurons

    PubMed Central

    Araya, Roberto

    2014-01-01

    In the mammalian brain, most inputs received by a neuron are formed on the dendritic tree. In the neocortex, the dendrites of pyramidal neurons are covered by thousands of tiny protrusions known as dendritic spines, which are the major recipient sites for excitatory synaptic information in the brain. Their peculiar morphology, with a small head connected to the dendritic shaft by a slender neck, has inspired decades of theoretical and more recently experimental work in an attempt to understand how excitatory synaptic inputs are processed, stored and integrated in pyramidal neurons. Advances in electrophysiological, optical and genetic tools are now enabling us to unravel the biophysical and molecular mechanisms controlling spine function in health and disease. Here I highlight relevant findings, challenges and hypotheses on spine function, with an emphasis on the electrical properties of spines and on how these affect the storage and integration of excitatory synaptic inputs in pyramidal neurons. In an attempt to make sense of the published data, I propose that the raison d'etre for dendritic spines lies in their ability to undergo activity-dependent structural and molecular changes that can modify synaptic strength, and hence alter the gain of the linearly integrated sub-threshold depolarizations in pyramidal neuron dendrites before the generation of a dendritic spike. PMID:25520626

  14. Analysis of dendritic spine morphology in cultured CNS neurons.

    PubMed

    Srivastava, Deepak P; Woolfrey, Kevin M; Penzes, Peter

    2011-07-13

    Dendritic spines are the sites of the majority of excitatory connections within the brain, and form the post-synaptic compartment of synapses. These structures are rich in actin and have been shown to be highly dynamic. In response to classical Hebbian plasticity as well as neuromodulatory signals, dendritic spines can change shape and number, which is thought to be critical for the refinement of neural circuits and the processing and storage of information within the brain. Within dendritic spines, a complex network of proteins link extracellular signals with the actin cyctoskeleton allowing for control of dendritic spine morphology and number. Neuropathological studies have demonstrated that a number of disease states, ranging from schizophrenia to autism spectrum disorders, display abnormal dendritic spine morphology or numbers. Moreover, recent genetic studies have identified mutations in numerous genes that encode synaptic proteins, leading to suggestions that these proteins may contribute to aberrant spine plasticity that, in part, underlie the pathophysiology of these disorders. In order to study the potential role of these proteins in controlling dendritic spine morphologies/number, the use of cultured cortical neurons offers several advantages. Firstly, this system allows for high-resolution imaging of dendritic spines in fixed cells as well as time-lapse imaging of live cells. Secondly, this in vitro system allows for easy manipulation of protein function by expression of mutant proteins, knockdown by shRNA constructs, or pharmacological treatments. These techniques allow researchers to begin to dissect the role of disease-associated proteins and to predict how mutations of these proteins may function in vivo.

  15. Sodium pump organization in dendritic spines.

    PubMed

    Blom, Hans; Bernhem, Kristoffer; Brismar, Hjalmar

    2016-10-01

    Advancement in fluorescence imaging with the invention of several super-resolution microscopy modalities (e.g., PALM/STORM and STED) has opened up the possibility of deciphering molecular distributions on the nanoscale. In our quest to better elucidate postsynaptic protein distribution in dendritic spines, we have applied these nanoscopy methods, where generated results could help improve our understanding of neuronal functions. In particular, we have investigated the principal energy transformer in the brain, i.e., the [Formula: see text]-ATPase (or sodium pump), an essential protein responsible for maintaining resting membrane potential and a major controller of intracellular ion homeostasis. In these investigations, we have focused on estimates of protein amount, giving assessments of how variations may depend on labeling strategies, sample analysis, and choice of nanoscopic imaging method, concluding that all can be critical factors for quantification. We present a comparison of these results and discuss the influences this may have for homeostatic sodium regulation in neurons and energy consumption.

  16. Neurotensin promotes the dendrite elongation and the dendritic spine maturation of the cerebral cortex in vitro.

    PubMed

    Gandou, Chihiro; Ohtani, Akiko; Senzaki, Kouji; Shiga, Takashi

    2010-03-01

    We examined roles of neurotensin in the dendrite formation and the maturation of dendritic spines in the rat cerebral cortex. Embryonic day (E) 18 cortical neurons were cultured for 2 or 4 days in the presence of neurotensin. The chronic treatment of cortical neurons with neurotensin for 4 days increased the dendritic length of non-GABAergic neurons. In addition, the acute treatment of cortical neurons for 24h at 3 days in vitro also increased the dendritic length of non-GABAergic neurons similarly but more strongly than the chronic treatment. In contrast, the acute treatment for 4h had no effects on the dendrite formation. Next, we examined the effects of neurotensin on the maturation of dendritic spines. E16 cortical neurons were cultured for 10 or 14 days in a basal medium and then treated with neurotensin for 24h. At 11 days in vitro, neurotensin increased the postsynaptic density (PSD) 95-positive dendritic protrusions (filopodia, puncta and spines) together with the increase of spine density and the decrease of puncta density. At 15 days in vitro, neurotensin decreased the puncta density. In addition, the immunohistochemical localization of neurotensin type 1 and type 3 receptors in cultured neurons suggested the differential contribution of the receptors in these effects. These findings suggest that neurotensin promotes the dendrite outgrowth and the maturation of dendritic spines of cultured cortical neurons, although further studies are needed to conclude that these roles of neurotensin are also the case in vivo.

  17. Abl2/Arg controls dendritic spine and dendrite arbor stability via distinct cytoskeletal control pathways.

    PubMed

    Lin, Yu-Chih; Yeckel, Mark F; Koleske, Anthony J

    2013-01-30

    Rho family GTPases coordinate cytoskeletal rearrangements in neurons, and mutations in their regulators are associated with mental retardation and other neurodevelopmental disorders (Billuart et al., 1998; Kutsche et al., 2000; Newey et al., 2005; Benarroch, 2007). Chromosomal microdeletions encompassing p190RhoGAP or its upstream regulator, the Abl2/Arg tyrosine kinase, have been observed in cases of mental retardation associated with developmental defects (Scarbrough et al., 1988; James et al., 1996; Takano et al., 1997; Chaabouni et al., 2006; Leal et al., 2009). Genetic knock-out of Arg in mice leads to synapse, dendritic spine, and dendrite arbor loss accompanied by behavioral deficits (Moresco et al., 2005; Sfakianos et al., 2007). To elucidate the cell-autonomous mechanisms by which Arg regulates neuronal stability, we knocked down Arg in mouse hippocampal neuronal cultures. We find that Arg knockdown significantly destabilizes dendrite arbors and reduces dendritic spine density by compromising dendritic spine stability. Inhibiting RhoA prevents dendrite arbor loss following Arg knockdown in neurons, but does not block spine loss. Interestingly, Arg-deficient neurons exhibit increased miniature EPSC amplitudes, and their remaining spines exhibit larger heads deficient in the actin stabilizing protein cortactin. Spine destabilization in Arg knockdown neurons is prevented by blocking NMDA receptor-dependent relocalization of cortactin from spines, or by forcing cortactin into spines via fusion to an actin-binding region of Arg. Thus, Arg employs distinct mechanisms to selectively regulate spine and dendrite stability: Arg dampens activity-dependent disruption of cortactin localization to stabilize spines and attenuates Rho activity to stabilize dendrite arbors.

  18. MIM-Induced Membrane Bending Promotes Dendritic Spine Initiation.

    PubMed

    Saarikangas, Juha; Kourdougli, Nazim; Senju, Yosuke; Chazal, Genevieve; Segerstråle, Mikael; Minkeviciene, Rimante; Kuurne, Jaakko; Mattila, Pieta K; Garrett, Lillian; Hölter, Sabine M; Becker, Lore; Racz, Ildikó; Hans, Wolfgang; Klopstock, Thomas; Wurst, Wolfgang; Zimmer, Andreas; Fuchs, Helmut; Gailus-Durner, Valérie; Hrabě de Angelis, Martin; von Ossowski, Lotta; Taira, Tomi; Lappalainen, Pekka; Rivera, Claudio; Hotulainen, Pirta

    2015-06-22

    Proper morphogenesis of neuronal dendritic spines is essential for the formation of functional synaptic networks. However, it is not known how spines are initiated. Here, we identify the inverse-BAR (I-BAR) protein MIM/MTSS1 as a nucleator of dendritic spines. MIM accumulated to future spine initiation sites in a PIP2-dependent manner and deformed the plasma membrane outward into a proto-protrusion via its I-BAR domain. Unexpectedly, the initial protrusion formation did not involve actin polymerization. However, PIP2-dependent activation of Arp2/3-mediated actin assembly was required for protrusion elongation. Overexpression of MIM increased the density of dendritic protrusions and suppressed spine maturation. In contrast, MIM deficiency led to decreased density of dendritic protrusions and larger spine heads. Moreover, MIM-deficient mice displayed altered glutamatergic synaptic transmission and compatible behavioral defects. Collectively, our data identify an important morphogenetic pathway, which initiates spine protrusions by coupling phosphoinositide signaling, direct membrane bending, and actin assembly to ensure proper synaptogenesis. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Dendritic spine dysgenesis contributes to hyperreflexia after spinal cord injury

    PubMed Central

    Bandaru, Samira P.; Liu, Shujun; Waxman, Stephen G.

    2014-01-01

    Hyperreflexia and spasticity are chronic complications in spinal cord injury (SCI), with limited options for safe and effective treatment. A central mechanism in spasticity is hyperexcitability of the spinal stretch reflex, which presents symptomatically as a velocity-dependent increase in tonic stretch reflexes and exaggerated tendon jerks. In this study we tested the hypothesis that dendritic spine remodeling within motor reflex pathways in the spinal cord contributes to H-reflex dysfunction indicative of spasticity after contusion SCI. Six weeks after SCI in adult Sprague-Dawley rats, we observed changes in dendritic spine morphology on α-motor neurons below the level of injury, including increased density, altered spine shape, and redistribution along dendritic branches. These abnormal spine morphologies accompanied the loss of H-reflex rate-dependent depression (RDD) and increased ratio of H-reflex to M-wave responses (H/M ratio). Above the level of injury, spine density decreased compared with below-injury spine profiles and spine distributions were similar to those for uninjured controls. As expected, there was no H-reflex hyperexcitability above the level of injury in forelimb H-reflex testing. Treatment with NSC23766, a Rac1-specific inhibitor, decreased the presence of abnormal dendritic spine profiles below the level of injury, restored RDD of the H-reflex, and decreased H/M ratios in SCI animals. These findings provide evidence for a novel mechanistic relationship between abnormal dendritic spine remodeling in the spinal cord motor system and reflex dysfunction in SCI. PMID:25505110

  20. Altered dendritic spine plasticity in cocaine-withdrawn rats.

    PubMed

    Shen, Hao-wei; Toda, Shigenobu; Moussawi, Khaled; Bouknight, Ashley; Zahm, Daniel S; Kalivas, Peter W

    2009-03-04

    Chronic cocaine treatment is associated with changes in dendritic spines in the nucleus accumbens, but it is unknown whether this neuroplasticity alters the effect of a subsequent cocaine injection on spine morphology and protein content. Three weeks after daily cocaine or saline administration, neurons in the accumbens were filled with the lipophilic dye, DiI. Although daily cocaine pretreatment did not alter spine density compared with daily saline, there was a shift from smaller to larger diameter spines. During the first 2 h after an acute cocaine challenge, a bidirectional change in spine head diameter and increase in spine density was measured in daily cocaine-pretreated animals. In contrast, no change in spine diameter or density was elicited by a cocaine challenge in daily saline animals during the first 2 h after injection. However, spine density was elevated at 6 h after a cocaine challenge in daily saline-pretreated animals. The time-dependent profile of proteins in the postsynaptic density subfraction elicited by a cocaine challenge in daily cocaine-pretreated subjects indicated that the changes in spine diameter and density were associated with a deteriorating actin cytoskeleton and a reduction in glutamate signaling-related proteins. Correspondingly, the amplitude of field potentials in accumbens evoked by stimulating prefrontal cortex was reduced for up to 6 h after acute cocaine in daily cocaine-withdrawn animals. These data indicate that daily cocaine pretreatment dysregulates dendritic spine plasticity elicited by a subsequent cocaine injection.

  1. Dendritic spine formation and synaptic function require neurobeachin

    PubMed Central

    Niesmann, Katharina; Breuer, Dorothee; Brockhaus, Johannes; Born, Gesche; Wolff, Ilka; Reissner, Carsten; Kilimann, Manfred W.; Rohlmann, Astrid; Missler, Markus

    2011-01-01

    A challenge in neuroscience is to understand the mechanisms underlying synapse formation. Most excitatory synapses in the brain are built on spines, which are actin-rich protrusions from dendrites. Spines are a major substrate of brain plasticity, and spine pathologies are observed in various mental illnesses. Here we investigate the role of neurobeachin (Nbea), a multidomain protein previously linked to cases of autism, in synaptogenesis. We show that deletion of Nbea leads to reduced numbers of spinous synapses in cultured neurons from complete knockouts and in cortical tissue from heterozygous mice, accompanied by altered miniature postsynaptic currents. In addition, excitatory synapses terminate mostly at dendritic shafts instead of spine heads in Nbea mutants, and actin becomes less enriched synaptically. As actin and synaptopodin, a spine-associated protein with actin-bundling activity, accumulate ectopically near the Golgi apparatus of mutant neurons, a role emerges for Nbea in trafficking important cargo to pre- and postsynaptic compartments. PMID:22109531

  2. EPSPs Measured in Proximal Dendritic Spines of Cortical Pyramidal Neurons.

    PubMed

    Acker, Corey D; Hoyos, Erika; Loew, Leslie M

    2016-01-01

    EPSPs occur when the neurotransmitter glutamate binds to postsynaptic receptors located on small pleomorphic membrane protrusions called dendritic spines. To transmit the synaptic signal, these potentials must travel through the spine neck and the dendritic tree to reach the soma. Due to their small size, the electrical behavior of spines and their ability to compartmentalize electrical signals has been very difficult to assess experimentally. In this study, we developed a method to perform simultaneous two-photon voltage-sensitive dye recording with two-photon glutamate uncaging in order to measure the characteristics (amplitude and duration) of uncaging-evoked EPSPs in single spines on the basal dendrites of L5 pyramidal neurons in acute brain slices from CD1 control mice. We were able to record uncaging-evoked spine potentials that resembled miniature EPSPs at the soma from a wide range of spine morphologies. In proximal spines, these potentials averaged 13.0 mV (range, 6.5-30.8 mV; N = 20) for an average somatic EPSP of 0.59 mV, whereas the mean attenuation ratio (spine/soma) was found to be 25.3. Durations of spine EPSP waveforms were found to be 11.7 ms on average. Modeling studies demonstrate the important role that spine neck resistance (Rneck) plays in spine EPSP amplitudes. Simulations used to estimate Rneck by fits to voltage-sensitive dye measurements produced a mean of 179 MΩ (range, 23-420 MΩ; N = 19). Independent measurements based on fluorescence recovery after photobleaching of a cytosolic dye from spines of the same population of neurons produced a mean R eck estimate of 204 MΩ (range, 52-521 MΩ; N = 34).

  3. Dendritic Spines in Depression: What We Learned from Animal Models

    PubMed Central

    Qiao, Hui; Li, Ming-Xing; Xu, Chang; Chen, Hui-Bin; An, Shu-Cheng; Ma, Xin-Ming

    2016-01-01

    Depression, a severe psychiatric disorder, has been studied for decades, but the underlying mechanisms still remain largely unknown. Depression is closely associated with alterations in dendritic spine morphology and spine density. Therefore, understanding dendritic spines is vital for uncovering the mechanisms underlying depression. Several chronic stress models, including chronic restraint stress (CRS), chronic unpredictable mild stress (CUMS), and chronic social defeat stress (CSDS), have been used to recapitulate depression-like behaviors in rodents and study the underlying mechanisms. In comparison with CRS, CUMS overcomes the stress habituation and has been widely used to model depression-like behaviors. CSDS is one of the most frequently used models for depression, but it is limited to the study of male mice. Generally, chronic stress causes dendritic atrophy and spine loss in the neurons of the hippocampus and prefrontal cortex. Meanwhile, neurons of the amygdala and nucleus accumbens exhibit an increase in spine density. These alterations induced by chronic stress are often accompanied by depression-like behaviors. However, the underlying mechanisms are poorly understood. This review summarizes our current understanding of the chronic stress-induced remodeling of dendritic spines in the hippocampus, prefrontal cortex, orbitofrontal cortex, amygdala, and nucleus accumbens and also discusses the putative underlying mechanisms. PMID:26881133

  4. Dendritic spine instability leads to progressive neocortical spine loss in a mouse model of Huntington's disease.

    PubMed

    Murmu, Reena Prity; Li, Wen; Holtmaat, Anthony; Li, Jia-Yi

    2013-08-07

    In Huntington's disease (HD), cognitive symptoms and cellular dysfunction precede the onset of classical motor symptoms and neuronal death in the striatum and cortex by almost a decade. This suggests that the early cognitive deficits may be due to a cellular dysfunction rather than being a consequence of neuronal loss. Abnormalities in dendritic spines are described in HD patients and in HD animal models. Available evidence indicates that altered spine and synaptic plasticity could underlie the motor as well as cognitive symptoms in HD. However, the exact kinetics of spine alterations and plasticity in HD remain unknown. We used long-term two-photon imaging through a cranial window, to track individual dendritic spines in a mouse model of HD (R6/2) as the disease progressed. In vivo imaging over a period of 6 weeks revealed a steady decrease in the density and survival of dendritic spines on cortical neurons of R6/2 mice compared with control littermates. Interestingly, we also observed increased spine formation in R6/2 mice throughout the disease. However, the probability that newly formed spines stabilized and transformed into persistent spines was greatly reduced compared with controls. In cultured neurons we found that mutant huntingtin causes a loss, in particular of mature spines. Furthermore, in R6/2 mice, aggregates of mutant huntingtin associate with dendritic spines. Alterations in dendritic spine dynamics, survival, and density in R6/2 mice were evident before the onset of motor symptoms, suggesting that decreased stability of the cortical synaptic circuitry underlies the early symptoms in HD.

  5. Computational Approach to Dendritic Spine Taxonomy and Shape Transition Analysis

    PubMed Central

    Bokota, Grzegorz; Magnowska, Marta; Kuśmierczyk, Tomasz; Łukasik, Michał; Roszkowska, Matylda; Plewczynski, Dariusz

    2016-01-01

    The common approach in morphological analysis of dendritic spines of mammalian neuronal cells is to categorize spines into subpopulations based on whether they are stubby, mushroom, thin, or filopodia shaped. The corresponding cellular models of synaptic plasticity, long-term potentiation, and long-term depression associate the synaptic strength with either spine enlargement or spine shrinkage. Although a variety of automatic spine segmentation and feature extraction methods were developed recently, no approaches allowing for an automatic and unbiased distinction between dendritic spine subpopulations and detailed computational models of spine behavior exist. We propose an automatic and statistically based method for the unsupervised construction of spine shape taxonomy based on arbitrary features. The taxonomy is then utilized in the newly introduced computational model of behavior, which relies on transitions between shapes. Models of different populations are compared using supplied bootstrap-based statistical tests. We compared two populations of spines at two time points. The first population was stimulated with long-term potentiation, and the other in the resting state was used as a control. The comparison of shape transition characteristics allowed us to identify the differences between population behaviors. Although some extreme changes were observed in the stimulated population, statistically significant differences were found only when whole models were compared. The source code of our software is freely available for non-commercial use1. Contact: d.plewczynski@cent.uw.edu.pl. PMID:28066226

  6. Principles of Long-Term Dynamics of Dendritic Spines

    PubMed Central

    Yasumatsu, Nobuaki; Matsuzaki, Masanori; Miyazaki, Takashi; Noguchi, Jun; Kasai, Haruo

    2008-01-01

    Long-term potentiation (LTP) of synapse strength requires enlargement of dendritic spines on cerebral pyramidal neurons. Long-term depression (LTD) is linked to spine shrinkage. Indeed, spines are dynamic structures: they form, change their shapes and volumes or can disappear in the space of hours. Do all such changes result from synaptic activity, or do some changes result from intrinsic processes? How do enlargement and shrinkage of spines relate to elimination and generation of spines, and how do these processes contribute to the stationary distribution of spine volumes? To answer these questions, we recorded the volumes of many individual spines daily for several days using two-photon imaging of CA1 pyramidal neurons in cultured slices of rat hippocampus between postnatal day 17 to 23. With normal synaptic transmission, spines often changed volume or were created or eliminated, thereby showing activity-dependent plasticity. However, we found that spines changed volume even after we blocked synaptic activity, reflecting a native instability of these small structures over the long term. Such “intrinsic fluctuations” showed unique dependence on spine volume. A mathematical model constructed from these data and the theory of random fluctuations explains population behaviors of spines, such as rates of elimination and generation, stationary distribution of volumes and the long-term persistence of large spines. Our study finds that generation and elimination of spines are more prevalent than previously believed, and spine volume shows significant correlation with its age and life expectancy. The population dynamics of spines also predict key psychological features of memory. PMID:19074033

  7. Educational Material for 3D Visualization of Spine Procedures: Methods for Creation and Dissemination.

    PubMed

    Cramer, Justin; Quigley, Edward; Hutchins, Troy; Shah, Lubdha

    2017-06-01

    Spine anatomy can be difficult to master and is essential for performing spine procedures. We sought to utilize the rapidly expanding field of 3D technology to create freely available, interactive educational materials for spine procedures. Our secondary goal was to convey lessons learned about 3D modeling and printing. This project involved two parallel processes: the creation of 3D-printed physical models and interactive digital models. We segmented illustrative CT studies of the lumbar and cervical spine to create 3D models and then printed them using a consumer 3D printer and a professional 3D printing service. We also included downloadable versions of the models in an interactive eBook and platform-independent web viewer. We then provided these educational materials to residents with a pretest and posttest to assess efficacy. The "Spine Procedures in 3D" eBook has been downloaded 71 times as of October 5, 2016. All models used in the book are available for download and printing. Regarding test results, the mean exam score improved from 70 to 86%, with the most dramatic improvement seen in the least experienced trainees. Participants reported increased confidence in performing lumbar punctures after exposure to the material. We demonstrate the value of 3D models, both digital and printed, in learning spine procedures. Moreover, 3D printing and modeling is a rapidly expanding field with a large potential role for radiologists. We have detailed our process for creating and sharing 3D educational materials in the hopes of motivating and enabling similar projects.

  8. Mu-opioid receptors modulate the stability of dendritic spines

    PubMed Central

    Liao, Dezhi; Lin, Hang; Law, Ping Yee; Loh, Horace H.

    2005-01-01

    Opioids classically regulate the excitability of neurons by suppressing synaptic GABA release from inhibitory neurons. Here, we report a role for opioids in modulating excitatory synaptic transmission. By activating ubiquitously clustered μ-opioid receptor (MOR) in excitatory synapses, morphine caused collapse of preexisting dendritic spines and decreased synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. Meanwhile, the opioid antagonist naloxone increased the density of spines. Chronic treatment with morphine decreased the density of dendritic spines even in the presence of Tetrodotoxin, a sodium channel blocker, indicating that the morphine's effect was not caused by altered activity in neural network through suppression of GABA release. The effect of morphine on dendritic spines was absent in transgenic mice lacking MORs and was blocked by CTOP (D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-ThrNH2), a μ-receptor antagonist. These data together with others suggest that endogenous opioids and/or constitutive activity of MORs participate in maintaining normal morphology and function of spines, challenging the classical model of opioids. Abnormal alteration of spines may occur in drug addiction when opioid receptors are overactivated by exogenous opiates. PMID:15659552

  9. Paradoxical signaling regulates structural plasticity in dendritic spines

    PubMed Central

    Rangamani, Padmini; Levy, Michael G.; Khan, Shahid; Oster, George

    2016-01-01

    Transient spine enlargement (3- to 5-min timescale) is an important event associated with the structural plasticity of dendritic spines. Many of the molecular mechanisms associated with transient spine enlargement have been identified experimentally. Here, we use a systems biology approach to construct a mathematical model of biochemical signaling and actin-mediated transient spine expansion in response to calcium influx caused by NMDA receptor activation. We have identified that a key feature of this signaling network is the paradoxical signaling loop. Paradoxical components act bifunctionally in signaling networks, and their role is to control both the activation and the inhibition of a desired response function (protein activity or spine volume). Using ordinary differential equation (ODE)-based modeling, we show that the dynamics of different regulators of transient spine expansion, including calmodulin-dependent protein kinase II (CaMKII), RhoA, and Cdc42, and the spine volume can be described using paradoxical signaling loops. Our model is able to capture the experimentally observed dynamics of transient spine volume. Furthermore, we show that actin remodeling events provide a robustness to spine volume dynamics. We also generate experimentally testable predictions about the role of different components and parameters of the network on spine dynamics. PMID:27551076

  10. Paradoxical Signaling Regulates Structural Plasticity in Dendritic Spines

    NASA Astrophysics Data System (ADS)

    Rangamani, Padmini; Levy, Michael; Khan, Shahid; Oster, George

    2016-02-01

    Transient spine enlargement (3-5 min timescale) is an important event associated with the structural plasticity of dendritic spines. Many of the molecular mechanisms associated with transient spine enlargement have been identified experimentally. Here, we use a systems biology approach to construct a mathematical model of biochemical signaling and actin-mediated transient spine expansion in response to calcium-influx due to NMDA receptor activation. We have identified that a key feature of this signaling network is the paradoxical signaling loop. Paradoxical components act bifunctionally in signaling networks and their role is to control both the activation and inhibition of a desired response function (protein activity or spine volume). Using ordinary differential equation (ODE)-based modeling, we show that the dynamics of different regulators of transient spine expansion including CaMKII, RhoA, and Cdc42 and the spine volume can be described using paradoxical signaling loops. Our model is able to capture the experimentally observed dynamics of transient spine volume. Furthermore, we show that actin remodeling events provide a robustness to spine volume dynamics. We also generate experimentally testable predictions about the role of different components and parameters of the network on spine dynamics.

  11. 3D CT spine data segmentation and analysis of vertebrae bone lesions.

    PubMed

    Peter, R; Malinsky, M; Ourednicek, P; Jan, J

    2013-01-01

    A method is presented aiming at detecting and classifying bone lesions in 3D CT data of human spine, via Bayesian approach utilizing Markov random fields. A developed algorithm for necessary segmentation of individual possibly heavily distorted vertebrae based on 3D intensity modeling of vertebra types is presented as well.

  12. The spine in 3D. Computed tomographic reformation from 2D axial sections.

    PubMed

    Virapongse, C; Gmitro, A; Sarwar, M

    1986-01-01

    A new program (3D83, General Electric) was used to reformat three-dimensional (3D) images from two-dimensional (2D) computed tomographic axial scans in 18 patients who had routine scans of the spine. The 3D spine images were extremely true to life and could be rotated around all three principle axes (constituting a movie), so that an illusion of head-motion parallax was created. The benefit of 3D reformation with this program is primarily for preoperative planning. It appears that 3D can also effectively determine the patency of foraminal stenosis by reformatting in hemisections. Currently this program is subject to several drawbacks that require user interaction and long reconstruction time. With further improvement, 3D reformation will find increasing clinical applicability.

  13. Automated spatio-temporal analysis of dendritic spines and related protein dynamics.

    PubMed

    On, Vincent; Zahedi, Atena; Ethell, Iryna M; Bhanu, Bir

    2017-01-01

    Cofilin and other Actin-regulating proteins are essential in regulating the shape of dendritic spines, which are sites of neuronal communications in the brain, and their malfunctions are implicated in neurodegeneration related to aging. The analysis of cofilin motility in dendritic spines using fluorescence video-microscopy may allow for the discovery of its effects on synaptic functions. To date, the flow of cofilin has not been analyzed by automatic means. This paper presents Dendrite Protein Analysis (DendritePA), a novel automated pattern recognition software to analyze protein trafficking in neurons. Using spatiotemporal information present in multichannel fluorescence videos, the DendritePA generates a temporal maximum intensity projection that enhances the signal-to-noise ratio of important biological structures, segments and tracks dendritic spines, estimates the density of proteins in spines, and analyzes the flux of proteins through the dendrite/spine boundary. The motion of a dendritic spine is used to generate spine energy images, which are used to automatically classify the shape of common dendritic spines such as stubby, mushroom, or thin. By tracking dendritic spines over time and using their intensity profiles, the system can analyze the flux patterns of cofilin and other fluorescently stained proteins. The cofilin flux patterns are found to correlate with the dynamic changes in dendritic spine shapes. Our results also have shown that the activation of cofilin using genetic manipulations leads to immature spines while its inhibition results in an increase in mature spines.

  14. Neurogranin regulates CaM dynamics at dendritic spines

    PubMed Central

    Petersen, Amber; Gerges, Nashaat Z.

    2015-01-01

    Calmodulin (CaM) plays a key role in synaptic function and plasticity due to its ability to mediate Ca2+ signaling. Therefore, it is essential to understand the dynamics of CaM at dendritic spines. In this study we have explored CaM dynamics using live-cell confocal microscopy and fluorescence recovery after photobleaching (FRAP) to study CaM diffusion. We find that only a small fraction of CaM in dendritic spines is immobile. Furthermore, the diffusion rate of CaM was regulated by neurogranin (Ng), a CaM-binding protein enriched at dendritic spines. Interestingly, Ng did not influence the immobile fraction of CaM at recovery plateau. We have previously shown that Ng enhances synaptic strength in a CaM-dependent manner. Taken together, these data indicate that Ng-mediated enhancement of synaptic strength is due to its ability to target, rather than sequester, CaM within dendritic spines. PMID:26084473

  15. Single-Voxel Recording of Voltage Transients in Dendritic Spines

    PubMed Central

    Acker, Corey D.; Yan, Ping; Loew, Leslie M.

    2011-01-01

    We report sensitive recording of membrane potential in single dendritic spines in cortical neurons within a brain slice using two-photon excitation and a new, fluorinated, intracellularly loaded organic dye, di-2-AN(F)EPPTEA. With a two-photon excitation wavelength of 1060 nm, we achieve voltage sensitivity of >16% change in fluorescence per 100 mV. By targeting single spines in single-voxel recordings, we attain excellent single/noise quality, with back-propagating action potentials (bAPs) visible in single sweeps while recording at 10 kHz. This recording rate allows us to reliably assess fast bAP dynamics on single sweeps including bAP rise times of 0.5 ms. The amplitude and propagation delays of the bAPs are similar among different spines located within the same dendritic region, and this is true despite large differences in spine size. The interregion differences in bAP waveforms in spines vary in relation to their distance from the soma and the caliber of their parent dendrites. PMID:21767473

  16. Activity-dependent trafficking of lysosomes in dendrites and dendritic spines.

    PubMed

    Goo, Marisa S; Sancho, Laura; Slepak, Natalia; Boassa, Daniela; Deerinck, Thomas J; Ellisman, Mark H; Bloodgood, Brenda L; Patrick, Gentry N

    2017-08-07

    In neurons, lysosomes, which degrade membrane and cytoplasmic components, are thought to primarily reside in somatic and axonal compartments, but there is little understanding of their distribution and function in dendrites. Here, we used conventional and two-photon imaging and electron microscopy to show that lysosomes traffic bidirectionally in dendrites and are present in dendritic spines. We find that lysosome inhibition alters their mobility and also decreases dendritic spine number. Furthermore, perturbing microtubule and actin cytoskeletal dynamics has an inverse relationship on the distribution and motility of lysosomes in dendrites. We also find trafficking of lysosomes is correlated with synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors. Strikingly, lysosomes traffic to dendritic spines in an activity-dependent manner and can be recruited to individual spines in response to local activation. These data indicate the position of lysosomes is regulated by synaptic activity and thus plays an instructive role in the turnover of synaptic membrane proteins. © 2017 Goo et al.

  17. Reduced Purkinje cell dendritic arborization and loss of dendritic spines in essential tremor.

    PubMed

    Louis, Elan D; Lee, Michelle; Babij, Rachel; Ma, Karen; Cortés, Etty; Vonsattel, Jean-Paul G; Faust, Phyllis L

    2014-12-01

    Based on accumulating post-mortem evidence of abnormalities in Purkinje cell biology in essential tremor, we hypothesized that regressive changes in dendritic morphology would be apparent in the Purkinje cell population in essential tremor cases versus age-matched controls. Cerebellar cortical tissue from 27 cases with essential tremor and 27 age-matched control subjects was processed by the Golgi-Kopsch method. Purkinje cell dendritic anatomy was quantified using a Neurolucida microscopic system interfaced with a motorized stage. In all measures, essential tremor cases demonstrated significant reductions in dendritic complexity compared with controls. Median values in essential tremor cases versus controls were: 5712.1 versus 10 403.2 µm (total dendrite length, P=0.01), 465.9 versus 592.5 µm (branch length, P=0.01), 22.5 versus 29.0 (maximum branch order, P=0.001), and 165.3 versus 311.7 (number of terminations, P=0.008). Furthermore, the dendritic spine density was reduced in essential tremor cases (medians=0.82 versus 1.02 µm(-1), P=0.03). Our demonstration of regressive changes in Purkinje cell dendritic architecture and spines in essential tremor relative to control brains provides additional evidence of a pervasive abnormality of Purkinje cell biology in this disease, which affects multiple neuronal cellular compartments including their axon, cell body, dendrites and spines.

  18. Structure and diversity of human dendritic spines evidenced by a new three-dimensional reconstruction procedure for Golgi staining and light microscopy.

    PubMed

    Reberger, Roman; Dall'Oglio, Aline; Jung, Claudio R; Rasia-Filho, Alberto A

    2017-09-05

    Different approaches aim to unravel detailed morphological features of neural cells. Dendritic spines are multifunctional units that reflect cellular connectivity, synaptic strength and plasticity. A novel three-dimensional (3D) reconstruction procedure is introduced for visualization of dendritic spines from human postmortem brain tissue using brightfield microscopy. The segmentation model was based on thresholding the intensity values of the dendritic spine image along 'z' stacks. We used median filtering and removed false positives. Fine adjustments during image processing confirmed that the reconstructed image of the spines corresponded to the actual original data. Examples are shown for the cortical amygdaloid nucleus and the CA3 hippocampal area. Structure of spine heads and necks was evaluated at different angles. Our 3D reconstruction images display dendritic spines either isolated or in clusters, in a continuum of shapes and sizes, from simple to more elaborated forms, including the presence of spinule and complex 'thorny excrescences'. The procedure has the advantages already described for the adapted "single-section" Golgi method, since it provides suitable results using human brains fixed in formalin for long time, is relatively easy, requires minimal equipment, and uses an algorithm for 3D reconstruction that provides high quality images and more precise morphological data. The procedure described here allows the reliable visualization and study of human dendritic spines with broad applications for normal controls and pathological studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Rapid Loss of Dendritic Spines after Stress Involves Derangement of Spine Dynamics by Corticotropin-Releasing Hormone

    PubMed Central

    Chen, Yuncai; Dubé, Céline M.; Rice, Courtney J.; Baram, Tallie Z.

    2008-01-01

    Chronic stress causes dendritic regression and loss of dendritic spines in hippocampal neurons that is accompanied by deficits in synaptic plasticity and memory. However, the responsible mechanisms remain unresolved. Here, we found that within hours of the onset of stress, the density of dendritic spines declined in vulnerable dendritic domains. This rapid, stress-induced spine loss was abolished by blocking the receptor (CRFR1) of corticotropin-releasing hormone (CRH), a hippocampal neuropeptide released during stress. Exposure to CRH provoked spine loss and dendritic regression in hippocampal organotypic cultures, and selective blockade of the CRFR1 receptor had the opposite effect. Live, time-lapse imaging revealed that CRH reduced spine density by altering dendritic spine dynamics: the peptide selectively and reversibly accelerated spine retraction, and this mechanism involved destabilization of spine F-actin. In addition, mice lacking the CRFR1 receptor had augmented spine density. These findings support a mechanistic role for CRH–CRFR1 signaling in stress-evoked spine loss and dendritic remodeling. PMID:18337421

  20. Structural and functional plasticity of dendritic spines - root or result of behavior?

    PubMed

    Gipson, C D; Olive, M F

    2017-01-01

    Dendritic spines are multifunctional integrative units of the nervous system and are highly diverse and dynamic in nature. Both internal and external stimuli influence dendritic spine density and morphology on the order of minutes. It is clear that the structural plasticity of dendritic spines is related to changes in synaptic efficacy, learning and memory and other cognitive processes. However, it is currently unclear whether structural changes in dendritic spines are primary instigators of changes in specific behaviors, a consequence of behavioral changes, or both. In this review, we first examine the basic structure and function of dendritic spines in the brain, as well as laboratory methods to characterize and quantify morphological changes in dendritic spines. We then discuss the existing literature on the temporal and functional relationship between changes in dendritic spines in specific brain regions and changes in specific behaviors mediated by those regions. Although technological advancements have allowed us to better understand the functional relevance of structural changes in dendritic spines that are influenced by environmental stimuli, the role of spine dynamics as an underlying driver or consequence of behavior still remains elusive. We conclude that while it is likely that structural changes in dendritic spines are both instigators and results of behavioral changes, improved research tools and methods are needed to experimentally and directly manipulate spine dynamics in order to more empirically delineate the relationship between spine structure and behavior. © 2016 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

  1. The dendritic spine story: an intriguing process of discovery

    PubMed Central

    DeFelipe, Javier

    2015-01-01

    Dendritic spines are key components of a variety of microcircuits and they represent the majority of postsynaptic targets of glutamatergic axon terminals in the brain. The present article will focus on the discovery of dendritic spines, which was possible thanks to the application of the Golgi technique to the study of the nervous system, and will also explore the early interpretation of these elements. This discovery represents an interesting chapter in the history of neuroscience as it shows us that progress in the study of the structure of the nervous system is based not only on the emergence of new techniques but also on our ability to exploit the methods already available and correctly interpret their microscopic images. PMID:25798090

  2. The dendritic spine story: an intriguing process of discovery.

    PubMed

    DeFelipe, Javier

    2015-01-01

    Dendritic spines are key components of a variety of microcircuits and they represent the majority of postsynaptic targets of glutamatergic axon terminals in the brain. The present article will focus on the discovery of dendritic spines, which was possible thanks to the application of the Golgi technique to the study of the nervous system, and will also explore the early interpretation of these elements. This discovery represents an interesting chapter in the history of neuroscience as it shows us that progress in the study of the structure of the nervous system is based not only on the emergence of new techniques but also on our ability to exploit the methods already available and correctly interpret their microscopic images.

  3. High Actin Concentrations in Brain Dendritic Spines and Postsynaptic Densities

    NASA Astrophysics Data System (ADS)

    Matus, Andrew; Ackermann, Marcel; Pehling, Gundula; Randolph Byers, H.; Fujiwara, Keigi

    1982-12-01

    Antibodies against actin were used to corroborate the presence of actin as a major component protein of isolated brain postsynaptic densities. The same antibodies also were used as an immunohistochemical stain to study the distribution of actin in sections of intact brain tissue. This showed two major sites where actin is concentrated: smooth muscle cells around blood vessels and postsynaptic sites. In the postsynaptic area the highest concentration of actin occurs in postsynaptic densities and there also is intense staining in the surrounding cytoplasm, especially within dendritic spines. Antiactin staining was much weaker in other parts of neurons and in glial cells. The high concentration of actin in dendritic spines may be related to shape changes that these structures have been found to undergo in response to prolonged afferent stimulation.

  4. Polarity Determinants in Dendritic Spine Development and Plasticity.

    PubMed

    Zhang, Huaye

    2016-01-01

    The asymmetric distribution of various proteins and RNAs is essential for all stages of animal development, and establishment and maintenance of this cellular polarity are regulated by a group of conserved polarity determinants. Studies over the last 10 years highlight important functions for polarity proteins, including apical-basal polarity and planar cell polarity regulators, in dendritic spine development and plasticity. Remarkably, many of the conserved polarity machineries function in similar manners in the context of spine development as they do in epithelial morphogenesis. Interestingly, some polarity proteins also utilize neuronal-specific mechanisms. Although many questions remain unanswered in our understanding of how polarity proteins regulate spine development and plasticity, current and future research will undoubtedly shed more light on how this conserved group of proteins orchestrates different pathways to shape the neuronal circuitry.

  5. Extracting generalized cylinder models of dendritic trees from 3D image stacks

    NASA Astrophysics Data System (ADS)

    Xu, Fenglian; Lewis, Paul H.; Chad, John E.; Wheal, Howard V.

    1998-06-01

    The automatic reconstruction of 3D structures from stacks of 2D images is an important problem in medical image analysis. In neuroscience, in particular, the availability of explicit 3D models of the dendritic tree structure of a neuron can be a valuable tool for understanding the complexity of neuronal function and neuronal morphology In this work, the dendritic tree structure is imaged at different levels through the tissue using a laser scanning confocal microscope. The aim of the software is to deliver an explicit representation of the tree as a generalized cylinder model. Automatic techniques often fail to produce a continuous 3D model and manual or semi-automatic techniques can be particularly labor intensive.In this paper we describe algorithms which lead to a continuous 3D cylinder model representation of the dendritic tree with a minimum of user involvement. The initial stage of the approach involves the identification of voxels with a high probability of being on the center-lines of the dendritic structure. These points are linked to form a skeleton using cost minimization techniques. In the final stage the full 3D structure is extracted around the center- lines and represented by generalized cylinders. This paper provides details of the algorithms in each of the stages together with some of the results of using the method on both synthetic and real data sets.

  6. Reliability of 3D reconstruction of the spine of mild scoliotic patients.

    PubMed

    Gille, Olivier; Champain, Nicolas; Benchikh-El-Fegoun, Abdelkrim; Vital, Jean-Marc; Skalli, Wafa

    2007-03-01

    A reliability study was conducted in quantitative 3-dimensional (3D) measurements for mild scoliosis. To evaluate the intrarater and interrater reliability of a computer tool used for 3D reconstruction of the spine. No reliability study of spinal in vivo 3D medical imaging measurements has been performed in the literature. This study included 30 patients (mean age 13 years) with mild idiopathic scoliosis. Spinal 3D reconstruction was performed using a new technique called semiautomatic 3D reconstruction, which requires only the location of the corners of each vertebral body on 2 orthogonal views. Three raters performed the 3D reconstruction procedure on the 30 pairs of radiographs in random order. One of the raters repeated the procedure for the 30 patients 15 days later. Inter-reliability and intra-reliability were estimated for different parameters: thoracic kyphosis, lumbar lordosis, Cobb's angle, pelvic morphologic and positional parameters, and axial rotation. Intraclass correlation coefficient showed good or very good agreement for most of the measurements. The 95% prediction limits are approximately 4 degrees for the measurements of spinal curves, 2 degrees for pelvic parameters, and axial vertebral rotation. The reliability of 3D reconstruction of the spine is acceptable, and this technique can be used for clinical studies.

  7. Morphological analysis of dendrites and spines by hybridization of ridge detection with twin support vector machine.

    PubMed

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Shao, Ying; Zhang, Yudong; Du, Sidan; Wu, Jane

    2016-01-01

    Dendritic spines are described as neuronal protrusions. The morphology of dendritic spines and dendrites has a strong relationship to its function, as well as playing an important role in understanding brain function. Quantitative analysis of dendrites and dendritic spines is essential to an understanding of the formation and function of the nervous system. However, highly efficient tools for the quantitative analysis of dendrites and dendritic spines are currently undeveloped. In this paper we propose a novel three-step cascaded algorithm-RTSVM- which is composed of ridge detection as the curvature structure identifier for backbone extraction, boundary location based on differences in density, the Hu moment as features and Twin Support Vector Machine (TSVM) classifiers for spine classification. Our data demonstrates that this newly developed algorithm has performed better than other available techniques used to detect accuracy and false alarm rates. This algorithm will be used effectively in neuroscience research.

  8. Morphological analysis of dendrites and spines by hybridization of ridge detection with twin support vector machine

    PubMed Central

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Shao, Ying; Zhang, Yudong

    2016-01-01

    Dendritic spines are described as neuronal protrusions. The morphology of dendritic spines and dendrites has a strong relationship to its function, as well as playing an important role in understanding brain function. Quantitative analysis of dendrites and dendritic spines is essential to an understanding of the formation and function of the nervous system. However, highly efficient tools for the quantitative analysis of dendrites and dendritic spines are currently undeveloped. In this paper we propose a novel three-step cascaded algorithm–RTSVM— which is composed of ridge detection as the curvature structure identifier for backbone extraction, boundary location based on differences in density, the Hu moment as features and Twin Support Vector Machine (TSVM) classifiers for spine classification. Our data demonstrates that this newly developed algorithm has performed better than other available techniques used to detect accuracy and false alarm rates. This algorithm will be used effectively in neuroscience research. PMID:27547530

  9. Multi-Level 3D Printing Implant For Reconstructing Cervical Spine With Metastatic Papillary Thyroid Carcinoma.

    PubMed

    Li, Xiucan; Wang, Yiguo; Zhao, Yongfei; Liu, Jianheng; Xiao, Songhua; Mao, Keya

    2017-05-11

    A unique case report. A three-dimensional (3D) printing technology is proposed for reconstructing multi-level cervical spine (C2-C4) after resection of metastatic papillary thyroid carcinoma in a middle-age female patient. Papillary thyroid carcinoma is a malignant neoplasm with a relatively favorable prognosis. A metastatic lesion in multi-level cervical spine (C2-C4) destroys neurological functions and causes local instability. Radical excision of the metastasis and reconstruction of the cervical vertebrae sequence conforms with therapeutic principles, while the special-shaped multi-level upper-cervical spine requires personalized implants. 3D printing is an additive manufacturing technology that produces personalized products by accurately layering material under digital model control via a computer. Reporting of this recent technology for reconstructing multi-level cervical spine (C2-C4) is rare in the literature. Anterior-posterior surgery was performed in one stage. Radical resection of the metastatic lesion (C2-C4) and thyroid gland, along with insertion of a personalized implant manufactured by 3D printing technology, were performed to rebuild the cervical spine sequences. The porous implant was printed in Ti6AL4 V with perfect physicochemical properties and biological performance, such as biocompatibility and osteogenic activity. Finally, lateral mass screw fixation was performed via a posterior approach. Patient neurological function gradually improved after the surgery. The patient received 11/17 on the Japanese Orthopedic Association scale and ambulated with a personalized skull-neck-thorax orthosis on postoperative day 11. She received radioiodine I therapy. The plane X-rays and computed tomography revealed no implant displacement or subsidence at the 12-month follow-up mark. The presented case substantiates the use of 3D printing technology, which enables the personalization of products to solve unconventional problems in spinal surgery. 5.

  10. Resolving lubrication layers in immersed boundary method simulations of vesicular transport in dendritic spines

    NASA Astrophysics Data System (ADS)

    Fai, Thomas; Kusters, Remy; Rycroft, Chris

    2015-11-01

    Our understanding of how neuronal connections in the brain are maintained and reorganized is being revolutionized by new experimental and computational techniques. Existing high-resolution 3D images show that neuronal axons often terminate onto micron-sized structures known as dendritic spines, which are characterized by their thin necks and bulbous heads. Vesicles containing membrane receptors must deform significantly to squeeze into the bulbous heads of the spines, but more quantitative estimates of the force and energy required are still lacking. We have used three-dimensional immersed boundary method simulations to capture the fluid dynamics of vesicle transport into spines. We vary the applied force and neck geometry to identify the region in phase space in which the vesicle can squeeze into the spine. These results are compared to pass-stuck diagrams computed previously in the case of vesicles squeezing through open channels with rigid walls. The resulting force estimates are found to be consistent with the physiological density of motor proteins. Resolving the thin lubricating layers between the vesicles and spine poses significant numerical challenges, and we have used elements from lubrication theory to help resolve these boundary layers.

  11. CHMP2B mutants linked to frontotemporal dementia impair maturation of dendritic spines.

    PubMed

    Belly, Agnès; Bodon, Gilles; Blot, Béatrice; Bouron, Alexandre; Sadoul, Rémy; Goldberg, Yves

    2010-09-01

    The highly conserved ESCRT-III complex is responsible for deformation and cleavage of membranes during endosomal trafficking and other cellular activities. In humans, dominant mutations in the ESCRT-III subunit CHMP2B cause frontotemporal dementia (FTD). The decade-long process leading to this cortical degeneration is not well understood. One possibility is that, akin to other neurodegenerative diseases, the pathogenic protein affects the integrity of dendritic spines and synapses before any neuronal death. Using confocal microscopy and 3D reconstruction, we examined whether expressing the FTD-linked mutants CHMP2B(intron5) and CHMP2B(Delta10) in cultured hippocampal neurons modified the number or structure of spines. Both mutants induced a significant decrease in the proportion of large spines with mushroom morphology, without overt degeneration. Furthermore, CHMP2B(Delta10) induced a drop in frequency and amplitude of spontaneous excitatory postsynaptic currents, suggesting that the more potent synapses were lost. These effects seemed unrelated to changes in autophagy. Depletion of endogenous CHMP2B by RNAi resulted in morphological changes similar to those induced by mutant CHMP2B, consistent with dominant-negative activity of pathogenic mutants. Thus, CHMP2B is required for spine growth. Taken together, these results demonstrate that a mutant ESCRT-III subunit linked to a human neurodegenerative disease can disrupt the normal pattern of spine development.

  12. CHMP2B mutants linked to frontotemporal dementia impair maturation of dendritic spines

    PubMed Central

    Belly, Agnès; Bodon, Gilles; Blot, Béatrice; Bouron, Alexandre; Sadoul, Rémy; Goldberg, Yves

    2010-01-01

    Summary The highly conserved ESCRT-III complex is responsible for deformation and cleavage of membranes during endosomal trafficking and other cellular activities. In humans, dominant mutations in the ESCRT-III subunit CHMP2B cause fronto-temporal dementia (FTD). The decade-long process leading to this cortical degeneration is not well understood. One possibility is that, akin to other neurodegenerative diseases, the pathogenic protein affects the integrity of dendritic spines and synapses before any neuronal death. Using confocal microscopy and 3D reconstruction, we examined whether expressing the FTD-linked mutants CHMP2Bintron5 and CHMP2BΔ10 in cultured hippocampal neurones modified the number or structure of spines. Both mutants induced a significant decrease in the proportion of large spines with mushroom morphology, without overt degeneration. Furthermore, CHMP2BΔ10 induced a drop in frequency and amplitude of spontaneous excitatory post-synaptic currents, suggesting that the more potent synapses were lost. These effects seemed unrelated to changes in autophagy. Depletion of endogenous CHMP2B by RNAi resulted in morphological changes similar to those induced by mutant CHMP2B, consistent with dominant negative activity of pathogenic mutants. Thus, CHMP2B is required for spine growth. Taken together, these results demonstrate that a mutant ESCRT-III subunit linked to a human neurodegenerative disease can disrupt the normal pattern of spine development. PMID:20699355

  13. A Postsynaptic Role for Short-Term Neuronal Facilitation in Dendritic Spines

    PubMed Central

    Yang, Sunggu; Santos, Mariton D.; Tang, Cha-Min; Kim, Jae Geun; Yang, Sungchil

    2016-01-01

    Synaptic plasticity is a fundamental component of information processing in the brain. Presynaptic facilitation in response to repetitive stimuli, often referred to as paired-pulse facilitation (PPF), is a dominant form of short-term synaptic plasticity. Recently, an additional cellular mechanism for short-term facilitation, short-term postsynaptic plasticity (STPP), has been proposed. While a dendritic mechanism was described in hippocampus, its expression has not yet been demonstrated at the levels of the spine. Furthermore, it is unknown whether the mechanism can be expressed in other brain regions, such as sensory cortex. Here, we demonstrated that a postsynaptic response can be facilitated by prior spine excitation in both hippocampal and cortical neurons, using 3D digital holography and two-photon calcium imaging. The coordinated action of pre- and post-synaptic plasticity may provide a more thorough account of information processing in the brain. PMID:27746721

  14. Modeling and Measurement of 3D Deformation of Scoliotic Spine Using 2D X-ray Images

    NASA Astrophysics Data System (ADS)

    Li, Hao; Leow, Wee Kheng; Huang, Chao-Hui; Howe, Tet Sen

    Scoliosis causes deformations such as twisting and lateral bending of the spine. To correct scoliotic deformation, the extents of 3D spinal deformation need to be measured. This paper studies the modeling and measurement of scoliotic spine based on 3D curve model. Through modeling the spine as a 3D Cosserat rod, the 3D structure of a scoliotic spine can be recovered by obtaining the minimum potential energy registration of the rod to the scoliotic spine in the x-ray image. Test results show that it is possible to obtain accurate 3D reconstruction using only the landmarks in a single view, provided that appropriate boundary conditions and elastic properties are included as constraints.

  15. Models and simulation of 3D neuronal dendritic trees using Bayesian networks.

    PubMed

    López-Cruz, Pedro L; Bielza, Concha; Larrañaga, Pedro; Benavides-Piccione, Ruth; DeFelipe, Javier

    2011-12-01

    Neuron morphology is crucial for neuronal connectivity and brain information processing. Computational models are important tools for studying dendritic morphology and its role in brain function. We applied a class of probabilistic graphical models called Bayesian networks to generate virtual dendrites from layer III pyramidal neurons from three different regions of the neocortex of the mouse. A set of 41 morphological variables were measured from the 3D reconstructions of real dendrites and their probability distributions used in a machine learning algorithm to induce the model from the data. A simulation algorithm is also proposed to obtain new dendrites by sampling values from Bayesian networks. The main advantage of this approach is that it takes into account and automatically locates the relationships between variables in the data instead of using predefined dependencies. Therefore, the methodology can be applied to any neuronal class while at the same time exploiting class-specific properties. Also, a Bayesian network was defined for each part of the dendrite, allowing the relationships to change in the different sections and to model heterogeneous developmental factors or spatial influences. Several univariate statistical tests and a novel multivariate test based on Kullback-Leibler divergence estimation confirmed that virtual dendrites were similar to real ones. The analyses of the models showed relationships that conform to current neuroanatomical knowledge and support model correctness. At the same time, studying the relationships in the models can help to identify new interactions between variables related to dendritic morphology.

  16. Fast 3D spine reconstruction of postoperative patients using a multilevel statistical model.

    PubMed

    Lecron, Fabian; Boisvert, Jonathan; Mahmoudi, Saïd; Labelle, Hubert; Benjelloun, Mohammed

    2012-01-01

    Severe cases of spinal deformities such as scoliosis are usually treated by a surgery where instrumentation (hooks, screws and rods) is installed to the spine to correct deformities. Even if the purpose is to obtain a normal spine curve, the result is often straighter than normal. In this paper, we propose a fast statistical reconstruction algorithm based on a general model which can deal with such instrumented spines. To this end, we present the concept of multilevel statistical model where the data are decomposed into a within-group and a between-group component. The reconstruction procedure is formulated as a second-order cone program which can be solved very fast (few tenths of a second). Reconstruction errors were evaluated on real patient data and results showed that multilevel modeling allows better 3D reconstruction than classical models.

  17. Seeing the spine in 3D: how will it change what we do?

    PubMed

    Labelle, Hubert; Aubin, Carl-Eric; Jackson, Roger; Lenke, Larry; Newton, Peter; Parent, Stefan

    2011-01-01

    The Scoliosis Research Society (SRS) has appointed a committee to evaluate the clinical relevance and impact of 3D analysis on scoliotic deformities and to develop a 3D classification of adolescent idiopathic scoliosis (AIS). The goal of this article is to summarize and present the work done in recent years within this committee and show how 3D analysis of AIS has the potential to change our current methods to analyse and treat scoliosis. A database of 600 3D reconstructions of the spine of patients with AIS has been established using calibrated PA and lateral radiographs obtained from either digital radiographs or the EOS system. The 3D reconstructions were done using dedicated software and analyzed with the "da Vinci" view, a schematic top view representation of the 3D reconstructions, which summarizes the position of the End-Apex-End vertebrae planes (planes of maximum curvature). Preliminary work was done using 3D reconstructions in 409 patients with AIS. Fuzzy clustering techniques were used to show that the cohort could be segmented in 5 easily differentiated curve patterns similar to those of the Lenke and King classifications. Two subsequent articles have shown that 3D reconstructions can be divided in different groups based on the location of the plane of maximum curvature of their curves. One study of 66 cases has shown a consistent loss of kyphosis within the 5 thoracic apical vertebrae. Finally, a study of 172 Lenke 1 curves analyzed by ISO Data cluster analysis has confirmed the presence of 2 statistically different subtypes according to the planes passing through the End-Apex-End vertebrae of the main thoracic curve. The study presented suggests that a valid and clinically useful 3D classification of AIS is within reach. 3D analysis has the potential to improve our comprehension of AIS curve types and automatic 3D classification may help decrease the known variability of current 2D classifications. Level III, systematic review of retrospective

  18. The structure and function of actin cytoskeleton in mature glutamatergic dendritic spines.

    PubMed

    Bellot, Alba; Guivernau, Biuse; Tajes, Marta; Bosch-Morató, Mònica; Valls-Comamala, Victòria; Muñoz, Francisco J

    2014-07-21

    Dendritic spines are actin-rich protrusions from the dendritic shaft, considered to be the locus where most synapses occur, as they receive the vast majority of excitatory connections in the central nervous system (CNS). Interestingly, hippocampal spines are plastic structures that contain a dense array of molecules involved in postsynaptic signaling and synaptic plasticity. Since changes in spine shape and size are correlated with the strength of excitatory synapses, spine morphology directly reflects spine function. Therefore several neuropathologies are associated with defects in proteins located at the spines. The present work is focused on the spine actin cytoskeleton attending to its structure and function mainly in glutamatergic neurons. It addresses the study of the structural plasticity of dendritic spines associated with long-term potentiation (LTP) and the mechanisms that underlie learning and memory formation. We have integrated the current knowledge on synaptic proteins to relate this plethora of molecules with actin and actin-binding proteins. We further included recent findings that outline key uncharacterized proteins that would be useful to unveil the real ultrastructure and function of dendritic spines. Furthermore, this review is directed to understand how such spine diversity and interplay contributes to the regulation of spine morphogenesis and dynamics. It highlights their physiological relevance in the brain function, as well as it provides insights for pathological processes affecting dramatically dendritic spines, such as Alzheimer's disease. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. From Synaptic Transmission to Cognition: An Intermediary Role for Dendritic Spines

    ERIC Educational Resources Information Center

    Gonzalez-Burgos, Ignacio

    2012-01-01

    Dendritic spines are cytoplasmic protrusions that develop directly or indirectly from the filopodia of neurons. Dendritic spines mediate excitatory neurotransmission and they can isolate the electrical activity generated by synaptic impulses, enabling them to translate excitatory afferent information via several types of plastic changes, including…

  20. From Synaptic Transmission to Cognition: An Intermediary Role for Dendritic Spines

    ERIC Educational Resources Information Center

    Gonzalez-Burgos, Ignacio

    2012-01-01

    Dendritic spines are cytoplasmic protrusions that develop directly or indirectly from the filopodia of neurons. Dendritic spines mediate excitatory neurotransmission and they can isolate the electrical activity generated by synaptic impulses, enabling them to translate excitatory afferent information via several types of plastic changes, including…

  1. High speed two-photon imaging of calcium dynamics in dendritic spines: consequences for spine calcium kinetics and buffer capacity.

    PubMed

    Cornelisse, L Niels; van Elburg, Ronald A J; Meredith, Rhiannon M; Yuste, Rafael; Mansvelder, Huibert D

    2007-10-24

    Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action potentials (AP) are almost never measured due to technical limitations, but they could be crucial for synaptic plasticity. With high-speed, precisely-targeted, two-photon point imaging we measured both calcium rise and decay kinetics in spines and secondary dendrites in neocortical pyramidal neurons. We found that both rise and decay kinetics of changes in calcium-indicator fluorescence are about twice as fast in spines. During AP trains, spine calcium changes follow each AP, but not in dendrites. Apart from the higher surface-to-volume ratio (SVR), we observed that neocortical dendritic spines have a markedly smaller endogenous buffer capacity with respect to their parental dendrites. Calcium influx time course and calcium extrusion rate were both in the same range for spines and dendrites when fitted with a dynamic multi-compartment model that included calcium binding kinetics and diffusion. In a subsequent analysis we used this model to investigate which parameters are critical determinants in spine calcium dynamics. The model confirmed the experimental findings: a higher SVR is not sufficient by itself to explain the faster rise time kinetics in spines, but only when paired with a lower buffer capacity in spines. Simulations at zero calcium-dye conditions show that calmodulin is more efficiently activated in spines, which indicates that spine morphology and buffering conditions in neocortical spines favor synaptic plasticity.

  2. 3D visualization of the scoliotic spine: longitudinal studies, data acquisition, and radiation dosage constraints

    NASA Astrophysics Data System (ADS)

    Kalvin, Alan D.; Adler, Roy L.; Margulies, Joseph Y.; Tresser, Charles P.; Wu, Chai W.

    1999-05-01

    Decision making in the treatment of scoliosis is typically based on longitudinal studies that involve the imaging and visualization the progressive degeneration of a patient's spine over a period of years. Some patients will need surgery if their spinal deformation exceeds a certain degree of severity. Currently, surgeons rely on 2D measurements, obtained from x-rays, to quantify spinal deformation. Clearly working only with 2D measurements seriously limits the surgeon's ability to infer 3D spinal pathology. Standard CT scanning is not a practical solution for obtaining 3D spinal measurements of scoliotic patients. Because it would expose the patient to a prohibitively high dose of radiation. We have developed 2 new CT-based methods of 3D spinal visualization that produce 3D models of the spine by integrating a very small number of axial CT slices with data obtained from CT scout data. In the first method the scout data are converted to sinogram data, and then processed by a tomographic image reconstruction algorithm. In the second method, the vertebral boundaries are detected in the scout data, and these edges are then used as linear constraints to determine 2D convex hulls of the vertebrae.

  3. The ROR2 tyrosine kinase receptor regulates dendritic spine morphogenesis in hippocampal neurons.

    PubMed

    Alfaro, Iván E; Varela-Nallar, Lorena; Varas-Godoy, Manuel; Inestrosa, Nibaldo C

    2015-07-01

    Wnt signaling regulates synaptic development and function and contributes to the fine-tuning of the molecular and morphological differentiation of synapses. We have shown previously that Wnt5a activates non-canonical Wnt signaling to stimulate postsynaptic differentiation in excitatory hippocampal neurons promoting the clustering of the postsynaptic scaffold protein PSD-95 and the development of dendritic spines. At least three different kinds of Wnt receptors have been associated with Wnt5a signaling: seven trans-membrane Frizzled receptors and the tyrosine kinase receptors Ryk and ROR2. We report here that ROR2 is distributed in the dendrites of hippocampal neurons in close proximity to synaptic contacts and it is contained in dendritic spine protrusions. We demonstrate that ROR2 is necessary to maintain dendritic spine number and morphological distribution in cultured hippocampal neurons. ROR2 overexpression increased dendritic spine growth without affecting the density of dendritic spine protrusions in a form dependent on its extracellular Wnt binding cysteine rich domain (CRD) and kinase domain. Overexpression of dominant negative ROR2 lacking the extracellular CRD decreased spine density and the proportion of mushroom like spines, while ROR2 lacking the C-terminal and active kinase domains only affected spine morphology. Our results indicate a crucial role of the ROR2 in the formation and maturation of the postsynaptic dendritic spines in hippocampal neurons. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Periodic F-actin structures shape the neck of dendritic spines

    PubMed Central

    Bär, Julia; Kobler, Oliver; van Bommel, Bas; Mikhaylova, Marina

    2016-01-01

    Most of the excitatory synapses on principal neurons of the forebrain are located on specialized structures called dendritic spines. Their morphology, comprising a spine head connected to the dendritic branch via a thin neck, provides biochemical and electrical compartmentalization during signal transmission. Spine shape is defined and tightly controlled by the organization of the actin cytoskeleton. Alterations in synaptic strength correlate with changes in the morphological appearance of the spine head and neck. Therefore, it is important to get a better understanding of the nanoscale organization of the actin cytoskeleton in dendritic spines. A periodic organization of the actin/spectrin lattice was recently discovered in axons and a small fraction of dendrites using super-resolution microscopy. Here we use a small probe phalloidin-Atto647N, to label F-actin in mature hippocampal primary neurons and in living hippocampal slices. STED nanoscopy reveals that in contrast to β-II spectrin antibody labelling, phalloidin-Atto647N stains periodic actin structures in all dendrites and the neck of nearly all dendritic spines, including filopodia-like spines. These findings extend the current view on F-actin organization in dendritic spines and may provide new avenues for understanding the structural changes in the spine neck during induction of synaptic plasticity, active organelle transport or tethering. PMID:27841352

  5. Periodic F-actin structures shape the neck of dendritic spines.

    PubMed

    Bär, Julia; Kobler, Oliver; van Bommel, Bas; Mikhaylova, Marina

    2016-11-14

    Most of the excitatory synapses on principal neurons of the forebrain are located on specialized structures called dendritic spines. Their morphology, comprising a spine head connected to the dendritic branch via a thin neck, provides biochemical and electrical compartmentalization during signal transmission. Spine shape is defined and tightly controlled by the organization of the actin cytoskeleton. Alterations in synaptic strength correlate with changes in the morphological appearance of the spine head and neck. Therefore, it is important to get a better understanding of the nanoscale organization of the actin cytoskeleton in dendritic spines. A periodic organization of the actin/spectrin lattice was recently discovered in axons and a small fraction of dendrites using super-resolution microscopy. Here we use a small probe phalloidin-Atto647N, to label F-actin in mature hippocampal primary neurons and in living hippocampal slices. STED nanoscopy reveals that in contrast to β-II spectrin antibody labelling, phalloidin-Atto647N stains periodic actin structures in all dendrites and the neck of nearly all dendritic spines, including filopodia-like spines. These findings extend the current view on F-actin organization in dendritic spines and may provide new avenues for understanding the structural changes in the spine neck during induction of synaptic plasticity, active organelle transport or tethering.

  6. Reelin Regulates the Maturation of Dendritic Spines, Synaptogenesis and Glial Ensheathment of Newborn Granule Cells

    PubMed Central

    Bosch, Carles; Masachs, Nuria; Exposito-Alonso, David; Martínez, Albert; Teixeira, Cátia M.; Fernaud, Isabel; Pujadas, Lluís; Ulloa, Fausto; Comella, Joan X.; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2016-01-01

    The Reelin pathway is essential for both neural migration and for the development and maturation of synaptic connections. However, its role in adult synaptic formation and remodeling is still being investigated. Here, we investigated the impact of the Reelin/Dab1 pathway on the synaptogenesis of newborn granule cells (GCs) in the young-adult mouse hippocampus. We show that neither Reelin overexpression nor the inactivation of its intracellular adapter, Dab1, substantially alters dendritic spine numbers in these neurons. In contrast, 3D-electron microscopy (focused ion beam milling/scanning electron microscope) revealed that dysregulation of the Reelin/Dab1 pathway leads to both transient and permanent changes in the types and morphology of dendritic spines, mainly altering mushroom, filopodial, and branched GC spines. We also found that the Reelin/Dab1 pathway controls synaptic configuration of presynaptic boutons in the dentate gyrus, with its dysregulation leading to a substantial decrease in multi-synaptic bouton innervation. Lastly, we show that the Reelin/Dab1 pathway controls astroglial ensheathment of synapses. Thus, the Reelin pathway is a key regulator of adult-generated GC integration, by controlling dendritic spine types and shapes, their synaptic innervation patterns, and glial ensheathment. These findings may help to better understanding of hippocampal circuit alterations in neurological disorders in which the Reelin pathway is implicated. Significance Statement The extracellular protein Reelin has an important role in neurological diseases, including epilepsy, Alzheimer's disease and psychiatric diseases, targeting hippocampal circuits. Here we address the role of Reelin in the development of synaptic contacts in adult-generated granule cells (GCs), a neuronal population that is crucial for learning and memory and implicated in neurological and psychiatric diseases. We found that the Reelin pathway controls the shapes, sizes, and types of dendritic

  7. Superresolving dendritic spine morphology with STED microscopy under holographic photostimulation

    PubMed Central

    Lauterbach, Marcel Andreas; Guillon, Marc; Desnos, Claire; Khamsing, Dany; Jaffal, Zahra; Darchen, François; Emiliani, Valentina

    2016-01-01

    Abstract. Emerging all-optical methods provide unique possibilities for noninvasive studies of physiological processes at the cellular and subcellular scale. On the one hand, superresolution microscopy enables observation of living samples with nanometer resolution. On the other hand, light can be used to stimulate cells due to the advent of optogenetics and photolyzable neurotransmitters. To exploit the full potential of optical stimulation, light must be delivered to specific cells or even parts of cells such as dendritic spines. This can be achieved with computer generated holography (CGH), which shapes light to arbitrary patterns by phase-only modulation. We demonstrate here in detail how CGH can be incorporated into a stimulated emission depletion (STED) microscope for photostimulation of neurons and monitoring of nanoscale morphological changes. We implement an original optical system to allow simultaneous holographic photostimulation and superresolution STED imaging. We present how synapses can be clearly visualized in live cells using membrane stains either with lipophilic organic dyes or with fluorescent proteins. We demonstrate the capabilities of this microscope to precisely monitor morphological changes of dendritic spines after stimulation. These all-optical methods for cell stimulation and monitoring are expected to spread to various fields of biological research in neuroscience and beyond. PMID:27413766

  8. Optimization of spine surgery planning with 3D image templating tools

    NASA Astrophysics Data System (ADS)

    Augustine, Kurt E.; Huddleston, Paul M.; Holmes, David R., III; Shridharani, Shyam M.; Robb, Richard A.

    2008-03-01

    The current standard of care for patients with spinal disorders involves a thorough clinical history, physical exam, and imaging studies. Simple radiographs provide a valuable assessment but prove inadequate for surgery planning because of the complex 3-dimensional anatomy of the spinal column and the close proximity of the neural elements, large blood vessels, and viscera. Currently, clinicians still use primitive techniques such as paper cutouts, pencils, and markers in an attempt to analyze and plan surgical procedures. 3D imaging studies are routinely ordered prior to spine surgeries but are currently limited to generating simple, linear and angular measurements from 2D views orthogonal to the central axis of the patient. Complex spinal corrections require more accurate and precise calculation of 3D parameters such as oblique lengths, angles, levers, and pivot points within individual vertebra. We have developed a clinician friendly spine surgery planning tool which incorporates rapid oblique reformatting of each individual vertebra, followed by interactive templating for 3D placement of implants. The template placement is guided by the simultaneous representation of multiple 2D section views from reformatted orthogonal views and a 3D rendering of individual or multiple vertebrae enabling superimposition of virtual implants. These tools run efficiently on desktop PCs typically found in clinician offices or workrooms. A preliminary study conducted with Mayo Clinic spine surgeons using several actual cases suggests significantly improved accuracy of pre-operative measurements and implant localization, which is expected to increase spinal procedure efficiency and safety, and reduce time and cost of the operation.

  9. The Spread of Ras Activity Triggered by Activation of a Single Dendritic Spine

    PubMed Central

    Harvey, Christopher D.; Yasuda, Ryohei; Zhong, Haining; Svoboda, Karel

    2009-01-01

    In neurons, individual dendritic spines isolate NMDA receptor-mediated Ca2+ accumulations from the dendrite and other spines. However, it is not known to what extent spines compartmentalize signaling events downstream of Ca2+ influx. We combined two-photon fluorescence lifetime imaging (FLIM) with two-photon glutamate uncaging to image the activity of the small GTPase Ras following NMDA receptor activation at individual spines. Induction of long-term potentiation (LTP) triggered robust Ca2+-dependent Ras activation in single spines that decayed in approximately 5 minutes. Ras activity spread over approximately 10 micrometers of dendrite and invaded neighboring spines by diffusion. The spread of Ras-dependent signaling was necessary for the local regulation of the threshold for LTP induction. Thus Ca2+-dependent synaptic signals can spread to couple multiple synapses on short stretches of dendrite. PMID:18556515

  10. Individualized 3D printing navigation template for pedicle screw fixation in upper cervical spine

    PubMed Central

    Guo, Fei; Dai, Jianhao; Zhang, Junxiang; Ma, Yichuan; Zhu, Guanghui; Shen, Junjie; Niu, Guoqi

    2017-01-01

    Purpose Pedicle screw fixation in the upper cervical spine is a difficult and high-risk procedure. The screw is difficult to place rapidly and accurately, and can lead to serious injury of spinal cord or vertebral artery. The aim of this study was to design an individualized 3D printing navigation template for pedicle screw fixation in the upper cervical spine. Methods Using CT thin slices data, we employed computer software to design the navigation template for pedicle screw fixation in the upper cervical spine (atlas and axis). The upper cervical spine models and navigation templates were produced by 3D printer with equal proportion, two sets for each case. In one set (Test group), pedicle screws fixation were guided by the navigation template; in the second set (Control group), the screws were fixed under fluoroscopy. According to the degree of pedicle cortex perforation and whether the screw needed to be refitted, the fixation effects were divided into 3 types: Type I, screw is fully located within the vertebral pedicle; Type II, degree of pedicle cortex perforation is <1 mm, but with good internal fixation stability and no need to renovate; Type III, degree of pedicle cortex perforation is >1 mm or with the poor internal fixation stability and in need of renovation. Type I and Type II were acceptable placements; Type III placements were unacceptable. Results A total of 19 upper cervical spine and 19 navigation templates were printed, and 37 pedicle screws were fixed in each group. Type I screw-placements in the test group totaled 32; Type II totaled 3; and Type III totaled 2; with an acceptable rate of 94.60%. Type I screw placements in the control group totaled 23; Type II totaled 3; and Type III totaled 11, with an acceptable rate of 70.27%. The acceptability rate in test group was higher than the rate in control group. The operation time and fluoroscopic frequency for each screw were decreased, compared with control group. Conclusion The individualized 3D

  11. Remodeling the Dendritic Spines in the Hindlimb Representation of the Sensory Cortex after Spinal Cord Hemisection in Mice.

    PubMed

    Zhang, Kexue; Zhang, Jinhui; Zhou, Yanmei; Chen, Chao; Li, Wei; Ma, Lei; Zhang, Licheng; Zhao, Jingxin; Gan, Wenbiao; Zhang, Lihai; Tang, Peifu

    2015-01-01

    Spinal cord injury (SCI) can induce remodeling of multiple levels of the cerebral cortex system especially in the sensory cortex. The aim of this study was to assess, in vivo and bilaterally, the remodeling of dendritic spines in the hindlimb representation of the sensory cortex after spinal cord hemisection. Thy1-YFP transgenic mice were randomly divided into the control group and the SCI group, and the spinal vertebral plates (T11-T12) of all mice were excised. Next, the left hemisphere of the spinal cord (T12) was hemisected in the SCI group. The hindlimb representations of the sensory cortex in both groups were imaged bilaterally on the day before (0d), and three days (3d), two weeks (2w), and one month (1m) after the SCI. The rates of stable, newly formed, and eliminated spines were calculated by comparing images of individual dendritic spine in the same areas at different time points. In comparison to the control group, the rate of newly formed spines in the contralateral sensory cortex of the SCI group increased at three days and two weeks after injury. The rates of eliminated spines in the bilateral sensory cortices increased and the rate of stable spines in the bilateral cortices declined at two weeks and one month. From three days to two weeks, the stable rates of bilaterally stable spines in the SCI group decreased. In comparison to the control group and contralateral cortex in the SCI group, the re-emerging rate of eliminated spines in ipsilateral cortex of the SCI group decreased significantly. The stable rates of newly formed spines in bilateral cortices of the SCI group decreased from two weeks to one month. We found that the remodeling in the hindlimb representation of the sensory cortex after spinal cord hemisection occurred bilaterally. This remodeling included eliminating spines and forming new spines, as well as changing the reorganized regions of the brain cortex after the SCI over time. Soon after the SCI, the cortex was remodeled by

  12. Chronic Ethanol During Adolescence Impacts Corticolimbic Dendritic Spines and Behavior.

    PubMed

    Jury, Nicholas J; Pollack, Gabrielle A; Ward, Meredith J; Bezek, Jessica L; Ng, Alexandra J; Pinard, Courtney R; Bergstrom, Hadley C; Holmes, Andrew

    2017-07-01

    Risk for alcohol use disorders (AUDs) in adulthood is linked to alcohol drinking during adolescence, but understanding of the neural and behavioral consequences of alcohol exposure during adolescence remains incomplete. Here, we examined the neurobehavioral impact of adolescent chronic intermittent EtOH (CIE) vapor exposure in mice. C57BL/6J-background Thy1-EGFP mice were CIE-exposed during adolescence or adulthood and examined, as adults, for alterations in the density and morphology of dendritic spines in infralimbic (IL) cortex, prelimbic (PL) cortex, and basolateral amygdala (BLA). In parallel, adolescent- and adult-exposed C57BL/6J mice were tested as adults for 2-bottle EtOH drinking, sensitivity to EtOH intoxication (loss of righting reflex [LORR]), blood EtOH clearance, and measures of operant responding for food reward. CIE during adolescence decreased IL neuronal spine density and increased the head width of relatively wide-head IL and BLA spines, whereas CIE decreased head width of relatively narrow-head BLA spines. Adolescents had higher EtOH consumption prior to CIE than adults, while CIE during adulthood, but not adolescence, increased EtOH consumption relative to pre-CIE baseline. CIE produced a tolerance-like decrease in LORR sensitivity to EtOH challenge, irrespective of the age at which mice received CIE exposure. Mice exposed to CIE during adolescence, but not adulthood, required more sessions than AIR controls to reliably respond for food reward on a fixed-ratio (FR) 1, but not subsequent FR3, reinforcement schedule. On a progressive ratio reinforcement schedule, break point responding was higher in the adolescent- than the adult-exposed mice, regardless of CIE. Finally, footshock punishment markedly suppressed responding for reward in all groups. Exposure to CIE during adolescence altered dendritic spine density and morphology in IL and BLA neurons, in parallel with a limited set of behavioral alterations. Together, these data add to growing

  13. Study of protein and RNA in dendritic spines using multi-isotope imaging mass spectrometry (MIMS).

    PubMed

    Brismar, H; Aperia, A; Westin, L; Moy, J; Wang, M; Guillermier, C; Poczatek, C; Lechene, C

    2014-11-01

    The classical view of neuronal protein synthesis is that proteins are made in the cell body and then transported to their functional sites in the dendrites and the dendritic spines. Indirect evidence, however, suggests that protein synthesis can directly occur in the distal dendrites, far from the cell body. We are developing protocols for dual labeling of RNA and proteins using (15)N-uridine and (18)O- or (13)C-leucine pulse chase in cultured neurons to identify and localize both protein synthesis and fate of newly synthesized proteins. Pilot experiments show discrete localization of both RNA and newly synthesized proteins in dendrites, close to dendritic spines. We have for the first time directly imaged and measured the production of proteins at the subcellular level in the neuronal dendrites, close to the functional sites, the dendritic spines. This will open a powerful way to study neural growth and synapse plasticity in health and disease.

  14. 3D visualization of HIV transfer at the virological synapse between dendritic cells and T cells

    PubMed Central

    Felts, Richard L.; Narayan, Kedar; Estes, Jacob D.; Shi, Dan; Trubey, Charles M.; Fu, Jing; Hartnell, Lisa M.; Ruthel, Gordon T.; Schneider, Douglas K.; Nagashima, Kunio; Bess, Julian W.; Bavari, Sina; Lowekamp, Bradley C.; Bliss, Donald; Lifson, Jeffrey D.; Subramaniam, Sriram

    2010-01-01

    The efficiency of HIV infection is greatly enhanced when the virus is delivered at conjugates between CD4+ T cells and virus-bearing antigen-presenting cells such as macrophages or dendritic cells via specialized structures known as virological synapses. Using ion abrasion SEM, electron tomography, and superresolution light microscopy, we have analyzed the spatial architecture of cell-cell contacts and distribution of HIV virions at virological synapses formed between mature dendritic cells and T cells. We demonstrate the striking envelopment of T cells by sheet-like membrane extensions derived from mature dendritic cells, resulting in a shielded region for formation of virological synapses. Within the synapse, filopodial extensions emanating from CD4+ T cells make contact with HIV virions sequestered deep within a 3D network of surface-accessible compartments in the dendritic cell. Viruses are detected at the membrane surfaces of both dendritic cells and T cells, but virions are not released passively at the synapse; instead, virus transfer requires the engagement of T-cell CD4 receptors. The relative seclusion of T cells from the extracellular milieu, the burial of the site of HIV transfer, and the receptor-dependent initiation of virion transfer by T cells highlight unique aspects of cell-cell HIV transmission. PMID:20624966

  15. GABA promotes the competitive selection of dendritic spines by controlling local Ca2+ signaling.

    PubMed

    Hayama, Tatsuya; Noguchi, Jun; Watanabe, Satoshi; Takahashi, Noriko; Hayashi-Takagi, Akiko; Ellis-Davies, Graham C R; Matsuzaki, Masanori; Kasai, Haruo

    2013-10-01

    Activity-dependent competition of synapses plays a key role in neural organization and is often promoted by GABA; however, its cellular bases are poorly understood. Excitatory synapses of cortical pyramidal neurons are formed on small protrusions known as dendritic spines, which exhibit structural plasticity. We used two-color uncaging of glutamate and GABA in rat hippocampal CA1 pyramidal neurons and found that spine shrinkage and elimination were markedly promoted by the activation of GABAA receptors shortly before action potentials. GABAergic inhibition suppressed bulk increases in cytosolic Ca(2+) concentrations, whereas it preserved the Ca(2+) nanodomains generated by NMDA-type receptors, both of which were necessary for spine shrinkage. Unlike spine enlargement, spine shrinkage spread to neighboring spines (<15 μm) and competed with their enlargement, and this process involved the actin-depolymerizing factor ADF/cofilin. Thus, GABAergic inhibition directly suppresses local dendritic Ca(2+) transients and strongly promotes the competitive selection of dendritic spines.

  16. Cortical regulation of dopamine depletion-induced dendritic spine loss in striatal medium spiny neurons.

    PubMed

    Neely, M D; Schmidt, D E; Deutch, A Y

    2007-10-26

    The proximate cause of Parkinson's disease is striatal dopamine depletion. Although no overt toxicity to striatal neurons has been reported in Parkinson's disease, one of the consequences of striatal dopamine loss is a decrease in the number of dendritic spines on striatal medium spiny neurons (MSNs). Dendrites of these neurons receive cortical glutamatergic inputs onto the dendritic spine head and dopaminergic inputs from the substantia nigra onto the spine neck. This synaptic arrangement suggests that dopamine gates corticostriatal glutamatergic drive onto spines. Using triple organotypic slice cultures composed of ventral mesencephalon, striatum, and cortex of the neonatal rat, we examined the role of the cortex in dopamine depletion-induced dendritic spine loss in MSNs. The striatal dopamine innervation was lesioned by treatment of the cultures with the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium (MPP+) or by removing the mesencephalon. Both MPP+ and mesencephalic ablation decreased MSN dendritic spine density. Analysis of spine morphology revealed that thin spines were preferentially lost after dopamine depletion. Removal of the cortex completely prevented dopamine depletion-induced spine loss. These data indicate that the dendritic remodeling of MSNs seen in parkinsonism occurs secondary to increases in corticostriatal glutamatergic drive, and suggest that modulation of cortical activity may be a useful therapeutic strategy in Parkinson's disease.

  17. Cortical Regulation of Dopamine Depletion-Induced Dendritic Spine Loss in Striatal Medium Spiny Neurons

    PubMed Central

    Neely, M. Diana; Schmidt, Dennis E.; Deutch, Ariel Y.

    2007-01-01

    The proximate cause of Parkinson’s Disease is striatal dopamine depletion. Although no overt toxicity to striatal neurons has been reported in Parkinson’s Disease, one of the consequences of striatal dopamine loss is a decrease in the number of dendritic spines on striatal medium spiny neurons (MSNs). Dendrites of these neurons receive cortical glutamatergic inputs onto the dendritic spine head and dopaminergic inputs from the substantia nigra onto the spine neck. This synaptic arrangement suggests that dopamine gates corticostriatal glutamatergic drive onto spines. Using triple organotypic slice cultures comprised of ventral mesencephalon, striatum, and cortex, we examined the role of the cortex in dopamine depletion-induced dendritic spine loss in MSNs. The striatal dopamine innervation was lesioned by treatment of the cultures with the dopaminergic neurotoxin MPP+ or by removing the mesencephalon. Both MPP+ and mesencephalic ablation decreased MSN dendritic spine density. Analysis of spine morphology revealed that thin spines were preferentially lost after dopamine depletion. Removal of the cortex completely prevented dopamine depletion-induced spine loss. These data indicate that the dendritic remodeling of MSNs seen in parkinsonism occurs secondary to increases in corticostriatal glutamatergic drive, and suggest that modulation of cortical activity may be a useful therapeutic strategy in Parkinson’s Disease. PMID:17888581

  18. The Flatness of Bifurcations in 3D Dendritic Trees: An Optimal Design.

    PubMed

    van Pelt, Jaap; Uylings, Harry B M

    2011-01-01

    The geometry of natural branching systems generally reflects functional optimization. A common property is that their bifurcations are planar and that daughter segments do not turn back in the direction of the parent segment. The present study investigates whether this also applies to bifurcations in 3D dendritic arborizations. This question was earlier addressed in a first study of flatness of 3D dendritic bifurcations by Uylings and Smit (1975), who used the apex angle of the right circular cone as flatness measure. The present study was inspired by recent renewed interest in this measure. Because we encountered ourselves shortcomings of this cone angle measure, the search for an optimal measure for flatness of 3D bifurcation was the second aim of our study. Therefore, a number of measures has been developed in order to quantify flatness and orientation properties of spatial bifurcations. All these measures have been expressed mathematically in terms of the three bifurcation angles between the three pairs of segments in the bifurcation. The flatness measures have been applied and evaluated to bifurcations in rat cortical pyramidal cell basal and apical dendritic trees, and to random spatial bifurcations. Dendritic and random bifurcations show significant different flatness measure distributions, supporting the conclusion that dendritic bifurcations are significantly more flat than random bifurcations. Basal dendritic bifurcations also show the property that their parent segments are generally aligned oppositely to the bisector of the angle between their daughter segments, resulting in "symmetrical" configurations. Such geometries may arise when during neuronal development the segments at a newly formed bifurcation are subjected to elastic tensions, which force the bifurcation into an equilibrium planar shape. Apical bifurcations, however, have parent segments oppositely aligned with one of the daughter segments. These geometries arise in the case of side

  19. The Flatness of Bifurcations in 3D Dendritic Trees: An Optimal Design

    PubMed Central

    van Pelt, Jaap; Uylings, Harry B. M.

    2012-01-01

    The geometry of natural branching systems generally reflects functional optimization. A common property is that their bifurcations are planar and that daughter segments do not turn back in the direction of the parent segment. The present study investigates whether this also applies to bifurcations in 3D dendritic arborizations. This question was earlier addressed in a first study of flatness of 3D dendritic bifurcations by Uylings and Smit (1975), who used the apex angle of the right circular cone as flatness measure. The present study was inspired by recent renewed interest in this measure. Because we encountered ourselves shortcomings of this cone angle measure, the search for an optimal measure for flatness of 3D bifurcation was the second aim of our study. Therefore, a number of measures has been developed in order to quantify flatness and orientation properties of spatial bifurcations. All these measures have been expressed mathematically in terms of the three bifurcation angles between the three pairs of segments in the bifurcation. The flatness measures have been applied and evaluated to bifurcations in rat cortical pyramidal cell basal and apical dendritic trees, and to random spatial bifurcations. Dendritic and random bifurcations show significant different flatness measure distributions, supporting the conclusion that dendritic bifurcations are significantly more flat than random bifurcations. Basal dendritic bifurcations also show the property that their parent segments are generally aligned oppositely to the bisector of the angle between their daughter segments, resulting in “symmetrical” configurations. Such geometries may arise when during neuronal development the segments at a newly formed bifurcation are subjected to elastic tensions, which force the bifurcation into an equilibrium planar shape. Apical bifurcations, however, have parent segments oppositely aligned with one of the daughter segments. These geometries arise in the case of side

  20. Olfactory experiences dynamically regulate plasticity of dendritic spines in granule cells of Xenopus tadpoles in vivo

    PubMed Central

    Zhang, Li; Huang, Yubin; Hu, Bing

    2016-01-01

    Granule cells, rich in dendrites with densely punctated dendritic spines, are the most abundant inhibitory interneurons in the olfactory bulb. The dendritic spines of granule cells undergo remodeling during the development of the nervous system. The morphological plasticity of the spines’ response to different olfactory experiences in vivo is not fully known. In initial studies, a single granule cell in Xenopus tadpoles was labeled with GFP plasmids via cell electroporation; then, morphologic changes of the granule cell spines were visualized by in vivo confocal time-lapse imaging. With the help of long-term imaging, the total spine density, dynamics, and stability of four types of dendritic spines (mushroom, stubby, thin and filopodia) were obtained. Morphological analysis demonstrated that odor enrichment produced a remarkable increase in the spine density and stability of large mushroom spine. Then, with the help of short-term imaging, we analyzed the morphological transitions among different spines. We found that transitions between small spines (thin and filopodia) were more easily influenced by odor stimulation or olfactory deprivation. These results indicate that different olfactory experiences can regulate the morphological plasticity of different dendritic spines in the granule cell. PMID:27713557

  1. Activity-dependent dendritic spine neck changes are correlated with synaptic strength.

    PubMed

    Araya, Roberto; Vogels, Tim P; Yuste, Rafael

    2014-07-15

    Most excitatory inputs in the mammalian brain are made on dendritic spines, rather than on dendritic shafts. Spines compartmentalize calcium, and this biochemical isolation can underlie input-specific synaptic plasticity, providing a raison d'etre for spines. However, recent results indicate that the spine can experience a membrane potential different from that in the parent dendrite, as though the spine neck electrically isolated the spine. Here we use two-photon calcium imaging of mouse neocortical pyramidal neurons to analyze the correlation between the morphologies of spines activated under minimal synaptic stimulation and the excitatory postsynaptic potentials they generate. We find that excitatory postsynaptic potential amplitudes are inversely correlated with spine neck lengths. Furthermore, a spike timing-dependent plasticity protocol, in which two-photon glutamate uncaging over a spine is paired with postsynaptic spikes, produces rapid shrinkage of the spine neck and concomitant increases in the amplitude of the evoked spine potentials. Using numerical simulations, we explore the parameter regimes for the spine neck resistance and synaptic conductance changes necessary to explain our observations. Our data, directly correlating synaptic and morphological plasticity, imply that long-necked spines have small or negligible somatic voltage contributions, but that, upon synaptic stimulation paired with postsynaptic activity, they can shorten their necks and increase synaptic efficacy, thus changing the input/output gain of pyramidal neurons.

  2. Activity-dependent dendritic spine neck changes are correlated with synaptic strength

    PubMed Central

    Araya, Roberto; Vogels, Tim P.; Yuste, Rafael

    2014-01-01

    Most excitatory inputs in the mammalian brain are made on dendritic spines, rather than on dendritic shafts. Spines compartmentalize calcium, and this biochemical isolation can underlie input-specific synaptic plasticity, providing a raison d’etre for spines. However, recent results indicate that the spine can experience a membrane potential different from that in the parent dendrite, as though the spine neck electrically isolated the spine. Here we use two-photon calcium imaging of mouse neocortical pyramidal neurons to analyze the correlation between the morphologies of spines activated under minimal synaptic stimulation and the excitatory postsynaptic potentials they generate. We find that excitatory postsynaptic potential amplitudes are inversely correlated with spine neck lengths. Furthermore, a spike timing-dependent plasticity protocol, in which two-photon glutamate uncaging over a spine is paired with postsynaptic spikes, produces rapid shrinkage of the spine neck and concomitant increases in the amplitude of the evoked spine potentials. Using numerical simulations, we explore the parameter regimes for the spine neck resistance and synaptic conductance changes necessary to explain our observations. Our data, directly correlating synaptic and morphological plasticity, imply that long-necked spines have small or negligible somatic voltage contributions, but that, upon synaptic stimulation paired with postsynaptic activity, they can shorten their necks and increase synaptic efficacy, thus changing the input/output gain of pyramidal neurons. PMID:24982196

  3. Clustered Dynamics of Inhibitory Synapses and Dendritic Spines in the Adult Neocortex

    PubMed Central

    Chen, Jerry L.; Villa, Katherine L; Cha, Jae Won; So, Peter T.C.; Kubota, Yoshiyuki; Nedivi, Elly

    2012-01-01

    A key feature of the mammalian brain is its capacity to adapt in response to experience, in part by remodeling of synaptic connections between neurons. Excitatory synapse rearrangements have been monitored in vivo by observation of dendritic spine dynamics, but lack of a vital marker for inhibitory synapses has precluded their observation. Here, we simultaneously monitor in vivo inhibitory synapse and dendritic spine dynamics across the entire dendritic arbor of pyramidal neurons in the adult mammalian cortex using large volume high-resolution dual color two-photon microscopy. We find that inhibitory synapses on dendritic shafts and spines differ in their distribution across the arbor and in their remodeling kinetics during normal and altered sensory experience. Further, we find inhibitory synapse and dendritic spine remodeling to be spatially clustered, and that clustering is influenced by sensory input. Our findings provide in vivo evidence for local coordination of inhibitory and excitatory synaptic rearrangements. PMID:22542188

  4. Spines slow down dendritic chloride diffusion and affect short-term ionic plasticity of GABAergic inhibition

    NASA Astrophysics Data System (ADS)

    Mohapatra, Namrata; Tønnesen, Jan; Vlachos, Andreas; Kuner, Thomas; Deller, Thomas; Nägerl, U. Valentin; Santamaria, Fidel; Jedlicka, Peter

    2016-03-01

    Cl‑ plays a crucial role in neuronal function and synaptic inhibition. However, the impact of neuronal morphology on the diffusion and redistribution of intracellular Cl‑ is not well understood. The role of spines in Cl‑ diffusion along dendritic trees has not been addressed so far. Because measuring fast and spatially restricted Cl‑ changes within dendrites is not yet technically possible, we used computational approaches to predict the effects of spines on Cl‑ dynamics in morphologically complex dendrites. In all morphologies tested, including dendrites imaged by super-resolution STED microscopy in live brain tissue, spines slowed down longitudinal Cl‑ diffusion along dendrites. This effect was robust and could be observed in both deterministic as well as stochastic simulations. Cl‑ extrusion altered Cl‑ diffusion to a much lesser extent than the presence of spines. The spine-dependent slowing of Cl‑ diffusion affected the amount and spatial spread of changes in the GABA reversal potential thereby altering homosynaptic as well as heterosynaptic short-term ionic plasticity at GABAergic synapses in dendrites. Altogether, our results suggest a fundamental role of dendritic spines in shaping Cl‑ diffusion, which could be of relevance in the context of pathological conditions where spine densities and neural excitability are perturbed.

  5. Role of dendritic spines in action potential backpropagation: a numerical simulation study.

    PubMed

    Tsay, David; Yuste, Rafael

    2002-11-01

    Two remarkable aspects of pyramidal neurons are their complex dendritic morphologies and the abundant presence of spines, small structures that are the sites of excitatory input. Although the channel properties of the dendritic shaft membrane have been experimentally probed, the influence of spine properties in dendritic signaling and action potential propagation remains unclear. To explore this we have performed multi-compartmental numerical simulations investigating the degree of consistency between experimental data on dendritic channel densities and backpropagation behavior, as well as the necessity and degree of influence of excitable spines. Our results indicate that measured densities of Na(+) channels in dendritic shafts cannot support effective backpropagation observed in apical dendrites due to suprathreshold inactivation. We demonstrate as a potential solution that Na(+) channels in spines at higher densities than those measured in the dendritic shaft can support extensive backpropagation. In addition, clustering of Na(+) channels in spines appears to enhance their effect due to their unique morphology. Finally, we show that changes in spine morphology significantly influence backpropagation efficacy. These results suggest that, by clustering sodium channels, spines may serve to control backpropagation.

  6. Spines slow down dendritic chloride diffusion and affect short-term ionic plasticity of GABAergic inhibition

    PubMed Central

    Mohapatra, Namrata; Tønnesen, Jan; Vlachos, Andreas; Kuner, Thomas; Deller, Thomas; Nägerl, U. Valentin; Santamaria, Fidel; Jedlicka, Peter

    2016-01-01

    Cl− plays a crucial role in neuronal function and synaptic inhibition. However, the impact of neuronal morphology on the diffusion and redistribution of intracellular Cl− is not well understood. The role of spines in Cl− diffusion along dendritic trees has not been addressed so far. Because measuring fast and spatially restricted Cl− changes within dendrites is not yet technically possible, we used computational approaches to predict the effects of spines on Cl− dynamics in morphologically complex dendrites. In all morphologies tested, including dendrites imaged by super-resolution STED microscopy in live brain tissue, spines slowed down longitudinal Cl− diffusion along dendrites. This effect was robust and could be observed in both deterministic as well as stochastic simulations. Cl− extrusion altered Cl− diffusion to a much lesser extent than the presence of spines. The spine-dependent slowing of Cl− diffusion affected the amount and spatial spread of changes in the GABA reversal potential thereby altering homosynaptic as well as heterosynaptic short-term ionic plasticity at GABAergic synapses in dendrites. Altogether, our results suggest a fundamental role of dendritic spines in shaping Cl− diffusion, which could be of relevance in the context of pathological conditions where spine densities and neural excitability are perturbed. PMID:26987404

  7. Spines slow down dendritic chloride diffusion and affect short-term ionic plasticity of GABAergic inhibition.

    PubMed

    Mohapatra, Namrata; Tønnesen, Jan; Vlachos, Andreas; Kuner, Thomas; Deller, Thomas; Nägerl, U Valentin; Santamaria, Fidel; Jedlicka, Peter

    2016-03-18

    Cl(-) plays a crucial role in neuronal function and synaptic inhibition. However, the impact of neuronal morphology on the diffusion and redistribution of intracellular Cl(-) is not well understood. The role of spines in Cl(-) diffusion along dendritic trees has not been addressed so far. Because measuring fast and spatially restricted Cl(-) changes within dendrites is not yet technically possible, we used computational approaches to predict the effects of spines on Cl(-) dynamics in morphologically complex dendrites. In all morphologies tested, including dendrites imaged by super-resolution STED microscopy in live brain tissue, spines slowed down longitudinal Cl(-) diffusion along dendrites. This effect was robust and could be observed in both deterministic as well as stochastic simulations. Cl(-) extrusion altered Cl(-) diffusion to a much lesser extent than the presence of spines. The spine-dependent slowing of Cl(-) diffusion affected the amount and spatial spread of changes in the GABA reversal potential thereby altering homosynaptic as well as heterosynaptic short-term ionic plasticity at GABAergic synapses in dendrites. Altogether, our results suggest a fundamental role of dendritic spines in shaping Cl(-) diffusion, which could be of relevance in the context of pathological conditions where spine densities and neural excitability are perturbed.

  8. Ca2+ signalling in postsynaptic dendrites and spines of mammalian neurons in brain slice.

    PubMed

    Müller, W; Connor, J A

    1992-01-01

    Postsynaptic Ca2+ changes are involved in control of cellular excitability and induction of synaptic long-term changes. We monitored Ca2+ changes in dendrites and spines during synaptic and direct stimulation using high resolution microfluorometry of fura-2 injected into CA3 pyramidal neurons in guinea pig hippocampal slice. When driven by current injection from an intracellular electrode or with synaptic stimulation, postsynaptic Ca2+ accumulations were highest in the proximal dendrites with a pronounced fall-off towards the soma and some fall-off towards more distal dendrites. Muscarinic activation by low concentrations of carbachol strongly increased intradendritic Ca2+ accumulation during directly-evoked repetitive firing. This enhancement occurred in large part because muscarinic activation suppressed the normal Ca(2+)-dependent activation of K-channels that mediates adaptation of firing. Repetitive firing of cholinergic fibers in the slice reproduced the effects of carbachol. Inhibition of acetylcholine-esterase activity by eserine enhanced the effects of repetitive stimulation of chlolinergic fibers. All effects were reversible and were blocked by the muscarinic antagonist atropine. Ca2+ accumulations in postsynaptic spines might be the basis of specificity of synaptic plasticity. With selective stimulation of few associative/comissural fibers, Ca2+ accumulated in single postsynaptic spines but not in the parent dendrite. With strong stimulation, dendrite levels also increased but spine levels were considerably higher. The NMDA-receptor antagonist AP-5 blocked Ca(2+)-peaks in spines, but left Ca2+ changes in dendrite shafts largely unaffected. Sustained steep Ca2+ gradients between single spines and the parent dendrite, often lasting several minutes, developed with repeated stimulation. Our results demonstrate a spine entity that can act independent from the dendrite with respect to Ca(2+)-dependent processes. Muscarinic augmentation of dendritic Ca2+ levels

  9. Molecular architecture of synaptic actin cytoskeleton in hippocampal neurons reveals a mechanism of dendritic spine morphogenesis.

    PubMed

    Korobova, Farida; Svitkina, Tatyana

    2010-01-01

    Excitatory synapses in the brain play key roles in learning and memory. The formation and functions of postsynaptic mushroom-shaped structures, dendritic spines, and possibly of presynaptic terminals, rely on actin cytoskeleton remodeling. However, the cytoskeletal architecture of synapses remains unknown hindering the understanding of synapse morphogenesis. Using platinum replica electron microscopy, we characterized the cytoskeletal organization and molecular composition of dendritic spines, their precursors, dendritic filopodia, and presynaptic boutons. A branched actin filament network containing Arp2/3 complex and capping protein was a dominant feature of spine heads and presynaptic boutons. Surprisingly, the spine necks and bases, as well as dendritic filopodia, also contained a network, rather than a bundle, of branched and linear actin filaments that was immunopositive for Arp2/3 complex, capping protein, and myosin II, but not fascin. Thus, a tight actin filament bundle is not necessary for structural support of elongated filopodia-like protrusions. Dynamically, dendritic filopodia emerged from densities in the dendritic shaft, which by electron microscopy contained branched actin network associated with dendritic microtubules. We propose that dendritic spine morphogenesis begins from an actin patch elongating into a dendritic filopodium, which tip subsequently expands via Arp2/3 complex-dependent nucleation and which length is modulated by myosin II-dependent contractility.

  10. Biophysical model of the role of actin remodeling on dendritic spine morphology

    PubMed Central

    Miermans, C. A.; Kusters, R. P. T.; Hoogenraad, C. C.; Storm, C.

    2017-01-01

    Dendritic spines are small membranous structures that protrude from the neuronal dendrite. Each spine contains a synaptic contact site that may connect its parent dendrite to the axons of neighboring neurons. Dendritic spines are markedly distinct in shape and size, and certain types of stimulation prompt spines to evolve, in fairly predictable fashion, from thin nascent morphologies to the mushroom-like shapes associated with mature spines. It is well established that the remodeling of spines is strongly dependent upon the actin cytoskeleton inside the spine. A general framework that details the precise role of actin in directing the transitions between the various spine shapes is lacking. We address this issue, and present a quantitative, model-based scenario for spine plasticity validated using realistic and physiologically relevant parameters. Our model points to a crucial role for the actin cytoskeleton. In the early stages of spine formation, the interplay between the elastic properties of the spine membrane and the protrusive forces generated in the actin cytoskeleton propels the incipient spine. In the maturation stage, actin remodeling in the form of the combined dynamics of branched and bundled actin is required to form mature, mushroom-like spines. Importantly, our model shows that constricting the spine-neck aids in the stabilization of mature spines, thus pointing to a role in stabilization and maintenance for additional factors such as ring-like F-actin structures. Taken together, our model provides unique insights into the fundamental role of actin remodeling and polymerization forces during spine formation and maturation. PMID:28158194

  11. Postsynaptic PDLIM5 / Enigma Homolog binds SPAR and causes dendritic spine shrinkage

    PubMed Central

    Herrick, Scott; Evers, Danielle M.; Lee, Ji-Yun; Udagawa, Noriko; Pak, Daniel T.S.

    2009-01-01

    Dendritic spine morphology is thought to play important roles in synaptic development and plasticity, and morphological derangements in spines are correlated with several neurological disorders. Here, we identified an interaction between Spine-Associated RapGAP (SPAR), a postsynaptic protein that reorganizes actin cytoskeleton and drives dendritic spine head growth, and PDLIM5 / Enigma Homolog (ENH), a PDZ-LIM (postsynaptic density-95/Discs large/zona occludens 1-Lin11/Isl-1/Mec3) family member. PDLIM5 has been implicated in susceptibility to bipolar disorder, major depression and schizophrenia but its function in neurological disease is poorly understood. We show that PDLIM5 is present in the postsynaptic density, where it promotes decreased dendritic spine head size and longer, filopodia-like morphology. Conversely, RNA interference against PDLIM5 or loss of PDLIM5 interaction with SPAR caused increased spine head diameter. Furthermore, PKC activation promoted delivery of PDLIM5 into dendritic spines and increased its spine colocalization with SPAR. These data reveal new postsynaptic functions for PDLIM5 in shrinkage of dendritic spines that may be relevant to its association with psychiatric illness. PMID:19900557

  12. Hippocampal Dendritic Spines Modifications Induced by Perinatal Asphyxia

    PubMed Central

    Saraceno, G. E.; Castilla, R.; Barreto, G. E.; Gonzalez, J.; Kölliker-Frers, R. A.; Capani, F.

    2012-01-01

    Perinatal asphyxia (PA) affects the synaptic function and morphological organization. In previous works, we have shown neuronal and synaptic changes in rat neostriatum subjected to hypoxia leading to long-term ubi-protein accumulation. Since F-actin is highly concentrated in dendritic spines, modifications in its organization could be related with alterations induced by hypoxia in the central nervous system (CNS). In the present study, we investigate the effects of PA on the actin cytoskeleton of hippocampal postsynaptic densities (PSD) in 4-month-old rats. PSD showed an increment in their thickness and in the level of ubiquitination. Correlative fluorescence-electron microscopy photooxidation showed a decrease in the number of F-actin-stained spines in hippocampal excitatory synapses subjected to PA. Although Western Blot analysis also showed a slight decrease in β-actin in PSD in PA animals, the difference was not significant. Taken together, this data suggests that long-term actin cytoskeleton might have role in PSD alterations which would be a spread phenomenon induced by PA. PMID:22645692

  13. Hippocampal dendritic spines modifications induced by perinatal asphyxia.

    PubMed

    Saraceno, G E; Castilla, R; Barreto, G E; Gonzalez, J; Kölliker-Frers, R A; Capani, F

    2012-01-01

    Perinatal asphyxia (PA) affects the synaptic function and morphological organization. In previous works, we have shown neuronal and synaptic changes in rat neostriatum subjected to hypoxia leading to long-term ubi-protein accumulation. Since F-actin is highly concentrated in dendritic spines, modifications in its organization could be related with alterations induced by hypoxia in the central nervous system (CNS). In the present study, we investigate the effects of PA on the actin cytoskeleton of hippocampal postsynaptic densities (PSD) in 4-month-old rats. PSD showed an increment in their thickness and in the level of ubiquitination. Correlative fluorescence-electron microscopy photooxidation showed a decrease in the number of F-actin-stained spines in hippocampal excitatory synapses subjected to PA. Although western blot analysis also showed a slight decrease in β-actin in PSD in PA animals, the difference was not significant. Taken together, this data suggests that long-term actin cytoskeleton might have role in PSD alterations which would be a spread phenomenon induced by PA.

  14. Semiautomated 3D Spine Reconstruction from Biplanar Radiographic Images: Prediction of Intervertebral Loading in Scoliotic Subjects

    PubMed Central

    Bassani, Tito; Ottardi, Claudia; Costa, Francesco; Brayda-Bruno, Marco; Wilke, Hans-Joachim; Galbusera, Fabio

    2017-01-01

    The present study proposes a semiautomatic software approach to reconstruct 3D subject-specific musculoskeletal model of thoracolumbar spine from radiographic digitized images acquired with EOS system. The approach is applied to evaluate the intervertebral loads in 38 standing adolescents with mild idiopathic scoliosis. For each vertebra, a set of landmarks was manually identified on radiographic images. The landmark coordinates were processed to calculate the following vertebral geometrical properties in the 3D space (i) location (ii) dimensions; and (iii) rotations. Spherical joints simulated disks, ligaments, and facet joints. Body weight distribution, muscles forces, and insertion points were placed according to physiological–anatomical values. Inverse static analysis, calculating joints’ reactions in maintaining assigned spine configuration, was performed with AnyBody software. Reaction forces were computed to quantify intervertebral loads, and correlation with the patient anatomical parameters was then checked. Preliminary validation was performed comparing the model outcomes with that obtained from other authors in previous modeling works and from in vivo measurements. The comparison with previous modeling works and in vivo studies partially fulfilled the preliminary validation purpose. However, minor incongruities were pointed out that need further investigations. The subjects’ intervertebral loads were found significantly correlated with the anatomical parameters in the sagittal and axial planes. Despite preliminary encouraging results that support model suitability, future investigations to consolidate the proposed approach are necessary. Nonetheless, the present method appears to be a promising tool that once fully validated could allow the subject-specific non-invasive evaluation of a deformed spine, providing supplementary information to the routine clinical examination and surgical intervention planning. PMID:28164082

  15. Semiautomated 3D Spine Reconstruction from Biplanar Radiographic Images: Prediction of Intervertebral Loading in Scoliotic Subjects.

    PubMed

    Bassani, Tito; Ottardi, Claudia; Costa, Francesco; Brayda-Bruno, Marco; Wilke, Hans-Joachim; Galbusera, Fabio

    2017-01-01

    The present study proposes a semiautomatic software approach to reconstruct 3D subject-specific musculoskeletal model of thoracolumbar spine from radiographic digitized images acquired with EOS system. The approach is applied to evaluate the intervertebral loads in 38 standing adolescents with mild idiopathic scoliosis. For each vertebra, a set of landmarks was manually identified on radiographic images. The landmark coordinates were processed to calculate the following vertebral geometrical properties in the 3D space (i) location (ii) dimensions; and (iii) rotations. Spherical joints simulated disks, ligaments, and facet joints. Body weight distribution, muscles forces, and insertion points were placed according to physiological-anatomical values. Inverse static analysis, calculating joints' reactions in maintaining assigned spine configuration, was performed with AnyBody software. Reaction forces were computed to quantify intervertebral loads, and correlation with the patient anatomical parameters was then checked. Preliminary validation was performed comparing the model outcomes with that obtained from other authors in previous modeling works and from in vivo measurements. The comparison with previous modeling works and in vivo studies partially fulfilled the preliminary validation purpose. However, minor incongruities were pointed out that need further investigations. The subjects' intervertebral loads were found significantly correlated with the anatomical parameters in the sagittal and axial planes. Despite preliminary encouraging results that support model suitability, future investigations to consolidate the proposed approach are necessary. Nonetheless, the present method appears to be a promising tool that once fully validated could allow the subject-specific non-invasive evaluation of a deformed spine, providing supplementary information to the routine clinical examination and surgical intervention planning.

  16. Dendritic spines disappear with chilling but proliferate excessively upon rewarming of mature hippocampus.

    PubMed

    Kirov, S A; Petrak, L J; Fiala, J C; Harris, K M

    2004-01-01

    More dendritic spine synapses occur on mature neurons in hippocampal slices by 2 h of incubation in vitro, than in perfusion-fixed hippocampus. What conditions initiate this spinogenesis and how rapidly do the spines begin to proliferate on mature neurons? To address these questions, CA1 field of the hippocampus neurons expressing green fluorescent protein in living slices from mature mice were imaged with two-photon microscopy. Spines disappeared and dendrites were varicose immediately after slice preparation in ice-cold artificial cerebrospinal fluid (ACSF). Electron microscopy (EM) revealed disrupted dendritic cytoplasm, enlarged or free-floating postsynaptic densities, and excessive axonal endocytosis. Upon warming dendritic varicosities shrank and spines rapidly reappeared within a few minutes illustrating the remarkable resilience of mature hippocampal neurons in slices. When membrane impermeant sucrose was substituted for NaCl in ACSF dendrites remained spiny at ice-cold temperatures and EM revealed less disruption. Nevertheless, spine number and length increased within 30 min in warm ACSF even when the extracellular calcium concentration was zero and synaptic transmission was blocked. When slices were first recovered for several hours and then chilled in 6 degrees C ACSF many spines disappeared and the dendrites became varicose. Upon re-warming varicosities shrank and spines reemerged in the same position from which they disappeared. In addition, new spines formed and spines were longer suggesting that chilling, not the initial injury from slicing, caused the spines to disappear while re-warming triggered the spine proliferation on mature neurons. The new spines might be a substrate for neuronal recovery of function, when neurons have been chilled or exposed to other traumatic conditions that disrupt ionic homeostasis.

  17. The impacts of geometry and binding on CaMKII diffusion and retention in dendritic spines

    PubMed Central

    Byrne, Michael J.; Waxham, M. Neal

    2013-01-01

    We used a particle-based Monte Carlo simulation to dissect the regulatory mechanism of molecular translocation of CaMKII, a key regulator of neuronal synaptic function. Geometry was based upon measurements from EM reconstructions of dendrites in CA1 hippocampal pyramidal neurons. Three types of simulations were performed to investigate the effects of geometry and other mechanisms that control CaMKII translocation in and out of dendritic spines. First, the diffusional escape rate of CaMKII from model spines of varied morphologies was examined. Second, a postsynaptic density (PSD) was added to study the impact of binding sites on this escape rate. Third, translocation of CaMKII from dendrites and trapping in spines was investigated using a simulated dendrite. Based on diffusion alone, a spine of average dimensions had the ability to retain CaMKII for duration of ~4 s. However, binding sites mimicking those in the PSD controlled the residence time of CaMKII in a highly nonlinear manner. In addition, we observed that F-actin at the spine head/neck junction had a significant impact on CaMKII trapping in dendritic spines. We discuss these results in the context of possible mechanisms that may explain the experimental results that have shown extended accumulation of CaMKII in dendritic spines during synaptic plasticity and LTP induction. PMID:21104309

  18. The correlation comparison of vertebral axial rotation relative to curvature and torsion in scoliosis by simplified 3D spine model.

    PubMed

    Lin, Hong

    2006-01-01

    This paper reports a study on correlation comparison of the vertebral axial rotation relative to curvature and torsion of scoliotic spine. The goal of this study is to understand whether the vertebral axial rotation is more correlated to the curvature or to the torsion of the scoliosis spinal deformity. For this purpose, the simplified 3D spine models are constructed on the randomly chosen images of scoliosis patients. The 3D spine model is based on two orthogonal spinal radiographic images taken from coronal and sagittal planes. Superimposed on these two images, the 3D Bezier curves are fitted interactively onto the center of the spine on both coronal and sagittal images. Upon the 3D Bezier Curve fitting, a series of simplified 3D vertebrae are implemented onto the 3D Bezier Curve proportional in size to its axis. The curvature and torsion then are obtained by difference quotients algorithm. In determining the vertebral axial rotation, the measurements are conducted directly on the coronal spine images. The lateral margins and centers of pedicles are used as landmarks for the rotation calculation. The correlation coefficients are calculated from both vertebral axial rotation relative to the curvature and to the torsion found on each vertebra. The strength of correlations from both cases is compared in the table.

  19. The dendritic spines of interneurons are dynamic structures influenced by PSA-NCAM expression.

    PubMed

    Guirado, Ramon; Perez-Rando, Marta; Sanchez-Matarredona, David; Castillo-Gómez, Esther; Liberia, Teresa; Rovira-Esteban, Laura; Varea, Emilio; Crespo, Carlos; Blasco-Ibáñez, José Miguel; Nacher, Juan

    2014-11-01

    Excitatory neurons undergo dendritic spine remodeling in response to different stimuli. However, there is scarce information about this type of plasticity in interneurons. The polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is a good candidate to mediate this plasticity as it participates in neuronal remodeling and is expressed by some mature cortical interneurons, which have reduced dendritic arborization, spine density, and synaptic input. To study the connectivity of the dendritic spines of interneurons and the influence of PSA-NCAM on their dynamics, we have analyzed these structures in a subpopulation of fluorescent spiny interneurons in the hippocampus of glutamic acid decarboxylase-enhanced green fluorescent protein transgenic mice. Our results show that these spines receive excitatory synapses. The depletion of PSA in vivo using the enzyme Endo-Neuraminidase-N (Endo-N) increases spine density when analyzed 2 days after, but decreases it 7 days after. The dendritic spine turnover was also analyzed in real time using organotypic hippocampal cultures: 24 h after the addition of EndoN, we observed an increase in the apparition rate of spines. These results indicate that dendritic spines are important structures in the control of the synaptic input of hippocampal interneurons and suggest that PSA-NCAM is relevant in the regulation of their morphology and connectivity.

  20. BDNF over-expression increases olfactory bulb granule cell dendritic spine density in vivo

    PubMed Central

    McDole, Brittnee; Isgor, Ceylan; Pare, Christopher; Guthrie, Kathleen

    2015-01-01

    Olfactory bulb granule cells are axon-less, inhibitory interneurons that regulate the activity of the excitatory output neurons, the mitral and tufted cells, through reciprocal dendrodendritic synapses located on granule cell spines. These contacts are established in the distal apical dendritic compartment, while granule cell basal dendrites and more proximal apical segments bear spines that receive glutamatergic inputs from the olfactory cortices. This synaptic connectivity is vital to olfactory circuit function and is remodeled during development, and in response to changes in sensory activity and lifelong granule cell neurogenesis. Manipulations that alter levels of the neurotrophin brain-derived neurotrophic factor (BDNF) in vivo have significant effects on dendritic spine morphology, maintenance and activity-dependent plasticity for a variety of CNS neurons, yet little is known regarding BDNF effects on bulb granule cell spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF produces a marked increase in granule cell spine density that includes an increase in mature spines on their apical dendrites. Morphometric analysis demonstrated that changes in spine density were most notable in the distal and proximal apical domains, indicating that multiple excitatory inputs are potentially modified by BDNF. Our results indicate that increased levels of endogenous BDNF can promote the maturation and/or maintenance of dendritic spines on granule cells, suggesting a role for this factor in modulating granule cell functional connectivity within adult olfactory circuitry. PMID:26211445

  1. BDNF over-expression increases olfactory bulb granule cell dendritic spine density in vivo.

    PubMed

    McDole, B; Isgor, C; Pare, C; Guthrie, K

    2015-09-24

    Olfactory bulb granule cells (GCs) are axon-less, inhibitory interneurons that regulate the activity of the excitatory output neurons, the mitral and tufted cells, through reciprocal dendrodendritic synapses located on GC spines. These contacts are established in the distal apical dendritic compartment, while GC basal dendrites and more proximal apical segments bear spines that receive glutamatergic inputs from the olfactory cortices. This synaptic connectivity is vital to olfactory circuit function and is remodeled during development, and in response to changes in sensory activity and lifelong GC neurogenesis. Manipulations that alter levels of the neurotrophin brain-derived neurotrophic factor (BDNF) in vivo have significant effects on dendritic spine morphology, maintenance and activity-dependent plasticity for a variety of CNS neurons, yet little is known regarding BDNF effects on bulb GC spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF in transgenic mice produces a marked increase in GC spine density that includes an increase in mature spines on their apical dendrites. Morphometric analysis demonstrated that changes in spine density were most notable in the distal and proximal apical domains, indicating that multiple excitatory inputs are potentially modified by BDNF. Our results indicate that increased levels of endogenous BDNF can promote the maturation and/or maintenance of dendritic spines on GCs, suggesting a role for this factor in modulating GC functional connectivity within adult olfactory circuitry.

  2. Casting a Net on Dendritic Spines: The Extracellular Matrix and its Receptors

    PubMed Central

    Dansie, Lorraine E.; Ethell, Iryna M.

    2011-01-01

    Dendritic spines are dynamic structures that accommodate the majority of excitatory synapses in the brain and are influenced by extracellular signals from presynaptic neurons, glial cells and the extracellular matrix (ECM). The ECM surrounds dendritic spines and extends into the synaptic cleft, maintaining synapse integrity as well as mediating trans-synaptic communications between neurons. Several scaffolding proteins and glycans that compose the ECM form a lattice-like network, which serves as an attractive ground for various secreted glycoproteins, lectins, growth factors and enzymes. ECM components can control dendritic spines through the interactions with their specific receptors or by influencing the functions of other synaptic proteins. In this review, we focus on ECM components and their receptors that regulate dendritic spine development and plasticity in the normal and diseased brain. PMID:21834084

  3. Dendritic spines as individual neuronal compartments for synaptic Ca2+ responses.

    PubMed

    Müller, W; Connor, J A

    1991-11-07

    The possibility that postsynaptic spines on neuronal dendrites are discrete biochemical compartments for Ca(2+)-activated processes involved in synaptic plasticity is a widely proposed concept that has eluded experimental demonstration. Using microfluorometry on CA3 neurons in hippocampal slices, we show here that with weak presynaptic stimulation of associative/commissural fibres, Ca2+ accumulates in single postsynaptic spines but not in the parent dendrite. Stronger stimulation also promotes changes in dendrites. The NMDA-receptor antagonist AP-5 blocks changes in Ca2+ in spines. Sustained steep Ca2+ gradients between single spines and the parent dendrite, often lasting several minutes, develop with repeated stimulation. The observed compartmentalization allows for the specificity, cooperativity and associativity displayed by memory models such as long-term potentiation.

  4. Methods of dendritic spine detection: from Golgi to high-resolution optical imaging.

    PubMed

    Mancuso, J J; Chen, Y; Li, X; Xue, Z; Wong, S T C

    2013-10-22

    Dendritic spines, the bulbous protrusions that form the postsynaptic half of excitatory synapses, are one of the most prominent features of neurons and have been imaged and studied for over a century. In that time, changes in the number and morphology of dendritic spines have been correlated to the developmental process as well as the pathophysiology of a number of neurodegenerative diseases. Due to the sheer scale of synaptic connectivity in the brain, work to date has merely scratched the surface in the study of normal spine function and pathology. This review will highlight traditional approaches to the imaging of dendritic spines and newer approaches made possible by advances in microscopy, protein engineering, and image analysis. The review will also describe recent work that is leading researchers toward the possibility of a systematic and comprehensive study of spine anatomy throughout the brain.

  5. Methods of Dendritic Spine Detection: from Golgi to High Resolution Optical Imaging

    PubMed Central

    Mancuso, James J; Chen, Yuanxin; Li, Xuping; Xue, Zhong

    2012-01-01

    Dendritic spines, the bulbous protrusions that form the postsynaptic half of excitatory synapses, are one of the most prominent features of neurons and have been imaged and studied for over a century. In that time, changes in the number and morphology of dendritic spines have been correlated to the developmental process as well as the pathophysiology of a number of neurodegenerative diseases. Due to the sheer scale of synaptic connectivity in the brain, work to date has merely scratched the surface in the study of normal spine function and pathology. This review will highlight traditional approaches to the imaging of dendritic spines and newer approaches made possible by advances in microscopy, protein engineering, and image analysis. The review will also describe recent work that is leading researchers toward the possibility of a systematic and comprehensive study of spine anatomy throughout the brain. PMID:22522468

  6. Dendritic Arborization and Spine Dynamics Are Abnormal in the Mouse Model of MECP2 Duplication Syndrome

    PubMed Central

    Jiang, Minghui; Ash, Ryan T.; Baker, Steven A.; Suter, Bernhard; Ferguson, Andrew; Park, Jiyoung; Rudy, Jessica; Torsky, Sergey P.; Chao, Hsiao-Tuan; Zoghbi, Huda Y.

    2013-01-01

    MECP2 duplication syndrome is a childhood neurological disorder characterized by intellectual disability, autism, motor abnormalities, and epilepsy. The disorder is caused by duplications spanning the gene encoding methyl-CpG-binding protein-2 (MeCP2), a protein involved in the modulation of chromatin and gene expression. MeCP2 is thought to play a role in maintaining the structural integrity of neuronal circuits. Loss of MeCP2 function causes Rett syndrome and results in abnormal dendritic spine morphology and decreased pyramidal dendritic arbor complexity and spine density. The consequences of MeCP2 overexpression on dendritic pathophysiology remain unclear. We used in vivo two-photon microscopy to characterize layer 5 pyramidal neuron spine turnover and dendritic arborization as a function of age in transgenic mice expressing the human MECP2 gene at twice the normal levels of MeCP2 (Tg1; Collins et al., 2004). We found that spine density in terminal dendritic branches is initially higher in young Tg1 mice but falls below control levels after postnatal week 12, approximately correlating with the onset of behavioral symptoms. Spontaneous spine turnover rates remain high in older Tg1 animals compared with controls, reflecting the persistence of an immature state. Both spine gain and loss rates are higher, with a net bias in favor of spine elimination. Apical dendritic arbors in both simple- and complex-tufted layer 5 Tg1 pyramidal neurons have more branches of higher order, indicating that MeCP2 overexpression induces dendritic overgrowth. P70S6K was hyperphosphorylated in Tg1 somatosensory cortex, suggesting that elevated mTOR signaling may underlie the observed increase in spine turnover and dendritic growth. PMID:24336718

  7. Characterization of 3D printing techniques: Toward patient specific quality assurance spine-shaped phantom for stereotactic body radiation therapy.

    PubMed

    Kim, Min-Joo; Lee, Seu-Ran; Lee, Min-Young; Sohn, Jason W; Yun, Hyong Geon; Choi, Joon Yong; Jeon, Sang Won; Suh, Tae Suk

    2017-01-01

    Development and comparison of spine-shaped phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet has been purposed to utilize in patient-specific quality assurance (QA) of stereotactic body radiation treatment. The developed 3D-printed spine QA phantom consisted of an acrylic body phantom and a 3D-printed spine shaped object. DLP and Polyjet 3D printers using a high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield units (HUs) were measured based on each CT image. Two different intensity-modulated radiotherapy plans based on both CT phantom image sets from the two printed spine-shaped phantoms with acrylic body phantoms were designed to deliver 16 Gy dose to the planning target volume (PTV) and were compared for target coverage and normal organ-sparing. Image fusion demonstrated good reproducibility of the developed phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than that for the Polyjet-generated phantom. The organs at risk received a lower dose for the 3D printed spine-shaped phantom image using the DLP technique than for the phantom image using the Polyjet technique. Despite using the same material for printing the spine-shaped phantom, these phantoms generated by different 3D printing techniques, DLP and Polyjet, showed different HU values and these differently appearing HU values according to the printing technique could be an extra consideration for developing the 3D printed spine-shaped phantom depending on the patient's age and the density of the spinal bone. Therefore, the 3D printing technique and materials should be carefully chosen by taking into account the condition of the patient in order to accurately produce 3D printed patient-specific QA

  8. Characterization of 3D printing techniques: Toward patient specific quality assurance spine-shaped phantom for stereotactic body radiation therapy

    PubMed Central

    Lee, Min-Young; Sohn, Jason W.; Yun, Hyong Geon; Choi, Joon Yong; Jeon, Sang Won

    2017-01-01

    Development and comparison of spine-shaped phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet has been purposed to utilize in patient-specific quality assurance (QA) of stereotactic body radiation treatment. The developed 3D-printed spine QA phantom consisted of an acrylic body phantom and a 3D-printed spine shaped object. DLP and Polyjet 3D printers using a high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield units (HUs) were measured based on each CT image. Two different intensity-modulated radiotherapy plans based on both CT phantom image sets from the two printed spine-shaped phantoms with acrylic body phantoms were designed to deliver 16 Gy dose to the planning target volume (PTV) and were compared for target coverage and normal organ-sparing. Image fusion demonstrated good reproducibility of the developed phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than that for the Polyjet-generated phantom. The organs at risk received a lower dose for the 3D printed spine-shaped phantom image using the DLP technique than for the phantom image using the Polyjet technique. Despite using the same material for printing the spine-shaped phantom, these phantoms generated by different 3D printing techniques, DLP and Polyjet, showed different HU values and these differently appearing HU values according to the printing technique could be an extra consideration for developing the 3D printed spine-shaped phantom depending on the patient’s age and the density of the spinal bone. Therefore, the 3D printing technique and materials should be carefully chosen by taking into account the condition of the patient in order to accurately produce 3D printed patient-specific QA

  9. Dendritic spine dysgenesis in superficial dorsal horn sensory neurons after spinal cord injury.

    PubMed

    Cao, Xiaoyu C; Pappalardo, Laura W; Waxman, Stephen G; Tan, Andrew M

    2017-01-01

    Neuropathic pain is a major complication of spinal cord injury, and despite aggressive efforts, this type of pain is refractory to available clinical treatment. Our previous work has demonstrated a structure-function link between dendritic spine dysgenesis on nociceptive sensory neurons in the intermediate zone, laminae IV/V, and chronic pain in central nervous system and peripheral nervous system injury models of neuropathic pain. To extend these findings, we performed a follow-up structural analysis to assess whether dendritic spine remodeling occurs on superficial dorsal horn neurons located in lamina II after spinal cord injury. Lamina II neurons are responsible for relaying deep, delocalized, often thermally associated pain commonly experienced in spinal cord injury pathologies. We analyzed dendritic spine morphometry and localization in tissue obtained from adult rats exhibiting neuropathic pain one-month following spinal cord injury. Although the total density of dendritic spines on lamina II neurons did not change after spinal cord injury, we observed an inverse relationship between the densities of thin- and mushroom-shaped spines: thin-spine density decreased while mushroom-spine density increased. These structural changes were specifically noted along dendritic branches within 150 µm from the soma, suggesting a possible adverse contribution to nociceptive circuit function. Intrathecal treatment with NSC23766, a Rac1-GTPase inhibitor, significantly reduced spinal cord injury-induced changes in both thin- and mushroom-shaped dendritic spines. Overall, these observations demonstrate that dendritic spine remodeling occurs in lamina II, regulated in part by the Rac1-signaling pathway, and suggests that structural abnormalities in this spinal cord region may also contribute to abnormal nociception after spinal cord injury.

  10. Dendritic spine dysgenesis in superficial dorsal horn sensory neurons after spinal cord injury

    PubMed Central

    Cao, Xiaoyu C; Pappalardo, Laura W; Waxman, Stephen G

    2017-01-01

    Neuropathic pain is a major complication of spinal cord injury, and despite aggressive efforts, this type of pain is refractory to available clinical treatment. Our previous work has demonstrated a structure–function link between dendritic spine dysgenesis on nociceptive sensory neurons in the intermediate zone, laminae IV/V, and chronic pain in central nervous system and peripheral nervous system injury models of neuropathic pain. To extend these findings, we performed a follow-up structural analysis to assess whether dendritic spine remodeling occurs on superficial dorsal horn neurons located in lamina II after spinal cord injury. Lamina II neurons are responsible for relaying deep, delocalized, often thermally associated pain commonly experienced in spinal cord injury pathologies. We analyzed dendritic spine morphometry and localization in tissue obtained from adult rats exhibiting neuropathic pain one-month following spinal cord injury. Although the total density of dendritic spines on lamina II neurons did not change after spinal cord injury, we observed an inverse relationship between the densities of thin- and mushroom-shaped spines: thin-spine density decreased while mushroom-spine density increased. These structural changes were specifically noted along dendritic branches within 150 µm from the soma, suggesting a possible adverse contribution to nociceptive circuit function. Intrathecal treatment with NSC23766, a Rac1-GTPase inhibitor, significantly reduced spinal cord injury-induced changes in both thin- and mushroom-shaped dendritic spines. Overall, these observations demonstrate that dendritic spine remodeling occurs in lamina II, regulated in part by the Rac1-signaling pathway, and suggests that structural abnormalities in this spinal cord region may also contribute to abnormal nociception after spinal cord injury. PMID:28326929

  11. Ibuprofen Protects from Cypermethrin-Induced Changes in the Striatal Dendritic Length and Spine Density.

    PubMed

    Tripathi, Pratibha; Singh, Ashish; Bala, Lakshmi; Patel, Devendra Kumar; Singh, Mahendra Pratap

    2017-03-25

    Microgliosis and inflammation are major wrongdoers in cypermethrin-induced Parkinsonism along with oxidative stress, mitochondrial dysfunction and α-synuclein aggregation. Dopamine depletion could alter dendritic morphology, length and spine number in the striatum. Present study investigated the effect of ibuprofen on the dendritic morphology, length and spine density in cypermethrin PD model. Male pups were treated intraperitoneally with cypermethrin during postnatal days followed by adulthood to induce Parkinsonism using standard procedure along with controls. Subsets of animals were pre-treated with ibuprofen 2 h prior to cypermethrin treatment during adulthood. Standard methods were used to confirm Parkinsonism/neuroprotection. Striatal dendritic morphology, length, spine number and expression of synaptophysin and postsynaptic density protein-95 (PSD-95) along with the nigrostriatal pro-inflammatory and apoptotic proteins were measured. Cypermethrin induced Parkinsonian traits and attenuated the dendritic length, spine number and expression of synaptophysin and PSD-95. While cypermethrin increased the expression of interleukin-1β, interleukin-4, interferon-γ, inducible nitric oxide synthase, caspase-3, caspase-9 and B-cell lymphoma (Bcl)-xl proteins, it attenuated Bcl-2 expression. Ibuprofen normalized the changes in dendritic morphology, length, spine number and expression of synaptophysin, PSD-95, and pro-inflammatory and apoptotic proteins. Results demonstrate that cypermethrin induces inflammation and alters dendritic morphology, length and spine number, which are encountered by ibuprofen.

  12. Automated Remote Focusing, Drift Correction, and Photostimulation to Evaluate Structural Plasticity in Dendritic Spines

    PubMed Central

    Evans, Paul R.; Garrett, Tavita R.; Yan, Long; Yasuda, Ryohei

    2017-01-01

    Long-term structural plasticity of dendritic spines plays a key role in synaptic plasticity, the cellular basis for learning and memory. The biochemical step is mediated by a complex network of signaling proteins in spines. Two-photon imaging techniques combined with two-photon glutamate uncaging allows researchers to induce and quantify structural plasticity in single dendritic spines. However, this method is laborious and slow, making it unsuitable for high throughput screening of factors necessary for structural plasticity. Here we introduce a MATLAB-based module built for Scanimage to automatically track, image, and stimulate multiple dendritic spines. We implemented an electrically tunable lens in combination with a drift correction algorithm to rapidly and continuously track targeted spines and correct sample movements. With a straightforward user interface to design custom multi-position experiments, we were able to adequately image and produce targeted plasticity in multiple dendritic spines using glutamate uncaging. Our methods are inexpensive, open source, and provides up to a five-fold increase in throughput for quantifying structural plasticity of dendritic spines. PMID:28114380

  13. The role of dendritic spine morphology in the compartmentalization and delivery of surface receptors.

    PubMed

    Simon, Cory M; Hepburn, Iain; Chen, Weiliang; De Schutter, Erik

    2014-06-01

    Since AMPA receptors are major molecular players in both short- and long-term plasticity, it is important to identify the time-scales of and factors affecting the lateral diffusion of AMPARs on the dendrite surface. Using a mathematical model, we study how the dendritic spine morphology affects two processes: (1) compartmentalization of the surface receptors in a single spine to retain local chemistry and (2) the delivery of receptors to the post-synaptic density (PSD) of spines via lateral diffusion following insertion onto the dendrite shaft. Computing the mean first passage time (MFPT) of surface receptors on a sample of real spine morphologies revealed that a constricted neck and bulbous head serve to compartmentalize receptors, consistent with previous works. The residence time of a Brownian diffusing receptor on the membrane of a single spine was computed to be ∼ 5 s. We found that the location of the PSD corresponds to the location at which the maximum MFPT occurs, the position that maximizes the residence time of a diffusing receptor. Meanwhile, the same geometric features of the spine that compartmentalize receptors inhibit the recruitment of AMPARs via lateral diffusion from dendrite insertion sites. Spines with narrow necks will trap a smaller fraction of diffusing receptors in the their PSD when considering competition for receptors between the spines, suggesting that ideal geometrical features involve a tradeoff depending on the intent of compartmentalizing the current receptor pool or recruiting new AMPARs in the PSD. The ultimate distribution of receptors among the spine PSDs by lateral diffusion from the dendrite shaft is an interplay between the insertion location and the shape and locations of both the spines and their PSDs. The time-scale for delivery of receptors to the PSD of spines via lateral diffusion was computed to be ∼ 60 s.

  14. Repetitive motor learning induces coordinated formation of clustered dendritic spines in vivo.

    PubMed

    Fu, Min; Yu, Xinzhu; Lu, Ju; Zuo, Yi

    2012-02-19

    Many lines of evidence suggest that memory in the mammalian brain is stored with distinct spatiotemporal patterns. Despite recent progresses in identifying neuronal populations involved in memory coding, the synapse-level mechanism is still poorly understood. Computational models and electrophysiological data have shown that functional clustering of synapses along dendritic branches leads to nonlinear summation of synaptic inputs and greatly expands the computing power of a neural network. However, whether neighbouring synapses are involved in encoding similar memory and how task-specific cortical networks develop during learning remain elusive. Using transcranial two-photon microscopy, we followed apical dendrites of layer 5 pyramidal neurons in the motor cortex while mice practised novel forelimb skills. Here we show that a third of new dendritic spines (postsynaptic structures of most excitatory synapses) formed during the acquisition phase of learning emerge in clusters, and that most such clusters are neighbouring spine pairs. These clustered new spines are more likely to persist throughout prolonged learning sessions, and even long after training stops, than non-clustered counterparts. Moreover, formation of new spine clusters requires repetition of the same motor task, and the emergence of succedent new spine(s) accompanies the strengthening of the first new spine in the cluster. We also show that under control conditions new spines appear to avoid existing stable spines, rather than being uniformly added along dendrites. However, succedent new spines in clusters overcome such a spatial constraint and form in close vicinity to neighbouring stable spines. Our findings suggest that clustering of new synapses along dendrites is induced by repetitive activation of the cortical circuitry during learning, providing a structural basis for spatial coding of motor memory in the mammalian brain.

  15. Vortioxetine promotes maturation of dendritic spines in vitro: A comparative study in hippocampal cultures.

    PubMed

    Waller, Jessica A; Chen, Fenghua; Sánchez, Connie

    2016-04-01

    Cognitive dysfunction is prevalent in patients with major depressive disorder (MDD), and cognitive impairments can persist after relief of depressive symptoms. The multimodal-acting antidepressant vortioxetine is an antagonist at 5-HT3, 5-HT7, and 5-HT1D receptors, a partial agonist at 5-HT1B receptors, an agonist at 5-HT1A receptors, and an inhibitor of the serotonin (5-HT) transporter (SERT) and has pro-cognitive properties. In preclinical studies, vortioxetine enhances long-term potentiation (LTP), a cellular correlate of neuroplasticity, and enhances memory in various cognitive tasks. However, the molecular mechanisms by which vortioxetine augments LTP and memory remain unknown. Dendritic spines are specialized, actin-rich microdomains on dendritic shafts and are major sites of most excitatory synapses. Since dendritic spine remodeling is implicated in synaptic plasticity and spine size dictates the strength of synaptic transmission, we assessed if vortioxetine, relative to other antidepressants including ketamine, duloxetine, and fluoxetine, plays a role in the maintenance of dendritic spine architecture in vitro. We show that vortioxetine, ketamine, and duloxetine induce spine enlargement. However, only vortioxetine treatment increased the number of spines in contact with presynaptic terminals. In contrast, fluoxetine had no effect on spine remodeling. These findings imply that the various 5-HT receptor mechanisms of vortioxetine may play a role in its effect on spine dynamics and in increasing the proportion of potentially functional synaptic contacts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Conductance transients onto dendritic spines in a segmental cable model of hippocampal neurons.

    PubMed Central

    Turner, D A

    1984-01-01

    Dendritic shaft (Zd) and spine (Zsp) input impedances were computed numerically for sites on hippocampal neurons, using a segmental format of cable calculations. The Zsp values for a typical spine appended onto a dendritic shaft averaged less than 2% higher than the Zd values for the adjacent dendritic shaft. Spine synaptic inputs were simulated by a brief conductance transient, which possessed a time integral of 12 X 10(-10)S X ms. This input resulted in an average peak spine response of 20 mV for both dentate granule neurons and CA1 pyramidal cells. The average spine transient was attenuated less than 2% in conduction across the spine neck, considering peak voltage, waveform parameters, and charge transfer. The spine conductance transient resulted in an average somatic response of 100 microV in the dentate granule neurons, because of passive electrotonic propagation. The same input transient was also applied to proximal and distal sites on CA1 pyramidal cells. The predicted responses at the soma demonstrated a clear difference between the proximal and distal inputs, in terms of both peak voltage and waveform parameters. Thus, the main determinant of the passive propagation of transient electrical signals in these neurons appears to be dendritic branching rather than signal attenuation through the spine neck. PMID:6743760

  17. BDNF pro-peptide regulates dendritic spines via caspase-3

    PubMed Central

    Guo, J; Ji, Y; Ding, Y; Jiang, W; Sun, Y; Lu, B; Nagappan, G

    2016-01-01

    The precursor of brain-derived neurotrophic factor (BDNF) (proBDNF) is enzymatically cleaved, by either intracellular (furin/PC1) or extracellular proteases (tPA/plasmin/MMP), to generate mature BDNF (mBDNF) and its pro-peptide (BDNF pro-peptide). Little is known about the function of BDNF pro-peptide. We have developed an antibody that specifically detects cleaved BDNF pro-peptide, but not proBDNF or mBDNF. Neuronal depolarization elicited a marked increase in extracellular BDNF pro-peptide, suggesting activity-dependent regulation of its extracellular levels. Exposure of BDNF pro-peptide to mature hippocampal neurons in culture dramatically reduced dendritic spine density. This effect was mediated by caspase-3, as revealed by studies with pharmacological inhibitors and genetic knockdown. BDNF pro-peptide also increased the number of ‘elongated' mitochondria and cytosolic cytochrome c, suggesting the involvement of mitochondrial-caspase-3 pathway. These results, along with BDNF pro-peptide effects recently reported on growth cones and long-term depression (LTD), suggest that BDNF pro-peptide is a negative regulator of neuronal structure and function. PMID:27310873

  18. BDNF pro-peptide regulates dendritic spines via caspase-3.

    PubMed

    Guo, J; Ji, Y; Ding, Y; Jiang, W; Sun, Y; Lu, B; Nagappan, G

    2016-06-16

    The precursor of brain-derived neurotrophic factor (BDNF) (proBDNF) is enzymatically cleaved, by either intracellular (furin/PC1) or extracellular proteases (tPA/plasmin/MMP), to generate mature BDNF (mBDNF) and its pro-peptide (BDNF pro-peptide). Little is known about the function of BDNF pro-peptide. We have developed an antibody that specifically detects cleaved BDNF pro-peptide, but not proBDNF or mBDNF. Neuronal depolarization elicited a marked increase in extracellular BDNF pro-peptide, suggesting activity-dependent regulation of its extracellular levels. Exposure of BDNF pro-peptide to mature hippocampal neurons in culture dramatically reduced dendritic spine density. This effect was mediated by caspase-3, as revealed by studies with pharmacological inhibitors and genetic knockdown. BDNF pro-peptide also increased the number of 'elongated' mitochondria and cytosolic cytochrome c, suggesting the involvement of mitochondrial-caspase-3 pathway. These results, along with BDNF pro-peptide effects recently reported on growth cones and long-term depression (LTD), suggest that BDNF pro-peptide is a negative regulator of neuronal structure and function.

  19. Learning curve of 3D fluoroscopy image-guided pedicle screw placement in the thoracolumbar spine.

    PubMed

    Ryang, Yu-Mi; Villard, Jimmy; Obermüller, Thomas; Friedrich, Benjamin; Wolf, Petra; Gempt, Jens; Ringel, Florian; Meyer, Bernhard

    2015-03-01

    During the past decade, a disproportionate increase of spinal fusion procedures has been observed. Along with this trend, image-guided spine surgery has been experiencing a renaissance in the recent years. A wide range of different navigation systems are available on the market today. However, only few published studies assess the learning curves concerning these new spinal navigation techniques. So far, a study on the learning curve for intraoperative three-dimensional fluoroscopy (3DFL)-navigated pedicle screw (PS) placement is still lacking. The purpose of the study was to analyze the learning curve for 3DFL-navigated thoracolumbar PS placement. The study design included a prospective case series. A cohort of 145 patients were recruited from January 2011 to June 2012. The outcome measures were duration of intraoperative 3D scans, PS placement, PS accuracy on postoperative computed tomography (CT) scans, and PS-related revisions and complications. From the introduction of spinal navigation to our department in January 2011 until June 2012, the learning curve for the duration of intraoperative 3D scan acquisition (navigation or control scan) and placement time per screw, intraoperative screw revisions, screw-related complications, revision surgeries, and PS accuracy on postoperative CT scans were assessed in 145 patients undergoing dorsal navigated instrumentation for 928 PS (736 lumbosacral and 192 thoracic). The observed time span was divided into four intervals. Results of the second, third, and last periods were compared with the first (reference) period, respectively. The mean navigation 3D scan time decreased (first and fourth periods) from 15.4±7.8 (range, 4-40) to 8.4±3.3 (3-15) minutes (p<.001). The mean control 3D scan time (after PS placement) decreased from 11.2±4.8 (5-25) to 6.6±3.0 (3-15) minutes (p<.001). The mean PS insertion time decreased from 5.3±2.5 (1-15) to 3.2±2.3 (1-17) minutes (p<.001). The mean proportion of correctly positioned PS

  20. Large and Small Dendritic Spines Serve Different Interacting Functions in Hippocampal Synaptic Plasticity and Homeostasis

    PubMed Central

    Paulin, Joshua J. W.; Haslehurst, Peter; Fellows, Alexander D.; Liu, Wenfei; Jackson, Joshua D.; Joel, Zelah; Cummings, Damian M.; Edwards, Frances A.

    2016-01-01

    The laying down of memory requires strong stimulation resulting in specific changes in synaptic strength and corresponding changes in size of dendritic spines. Strong stimuli can also be pathological, causing a homeostatic response, depressing and shrinking the synapse to prevent damage from too much Ca2+ influx. But do all types of dendritic spines serve both of these apparently opposite functions? Using confocal microscopy in organotypic slices from mice expressing green fluorescent protein in hippocampal neurones, the size of individual spines along sections of dendrite has been tracked in response to application of tetraethylammonium. This strong stimulus would be expected to cause both a protective homeostatic response and long-term potentiation. We report separation of these functions, with spines of different sizes reacting differently to the same strong stimulus. The immediate shrinkage of large spines suggests a homeostatic protective response during the period of potential danger. In CA1, long-lasting growth of small spines subsequently occurs consolidating long-term potentiation but only after the large spines return to their original size. In contrast, small spines do not change in dentate gyrus where potentiation does not occur. The separation in time of these changes allows clear functional differentiation of spines of different sizes. PMID:26881123

  1. Electrical and Ca2+ signaling in dendritic spines of substantia nigra dopaminergic neurons

    PubMed Central

    Hage, Travis A; Sun, Yujie; Khaliq, Zayd M

    2016-01-01

    Little is known about the density and function of dendritic spines on midbrain dopamine neurons, or the relative contribution of spine and shaft synapses to excitability. Using Ca2+ imaging, glutamate uncaging, fluorescence recovery after photobleaching and transgenic mice expressing labeled PSD-95, we comparatively analyzed electrical and Ca2+ signaling in spines and shaft synapses of dopamine neurons. Dendritic spines were present on dopaminergic neurons at low densities in live and fixed tissue. Uncaging-evoked potential amplitudes correlated inversely with spine length but positively with the presence of PSD-95. Spine Ca2+ signals were less sensitive to hyperpolarization than shaft synapses, suggesting amplification of spine head voltages. Lastly, activating spines during pacemaking, we observed an unexpected enhancement of spine Ca2+ midway throughout the spike cycle, likely involving recruitment of NMDA receptors and voltage-gated conductances. These results demonstrate functionality of spines in dopamine neurons and reveal a novel modulation of spine Ca2+ signaling during pacemaking. DOI: http://dx.doi.org/10.7554/eLife.13905.001 PMID:27163179

  2. DSCAM contributes to dendrite arborization and spine formation in the developing cerebral cortex.

    PubMed

    Maynard, Kristen R; Stein, Elke

    2012-11-21

    Down syndrome cell adhesion molecule, or DSCAM, has been implicated in many neurodevelopmental processes including axon guidance, dendrite arborization, and synapse formation. Here we show that DSCAM plays an important role in regulating the morphogenesis of cortical pyramidal neurons in the mouse. We report that DSCAM expression is developmentally regulated and localizes to synaptic plasma membranes during a time of robust cortical dendrite arborization and spine formation. Analysis of mice that carry a spontaneous mutation in DSCAM (DSCAM(del17)) revealed gross morphological changes in brain size and shape in addition to subtle changes in cortical organization, volume, and lamination. Early postnatal mutant mice displayed a transient decrease in cortical thickness, but these reductions could not be attributed to changes in neuron production or cell death. DSCAM(del17) mutants showed temporary impairments in the branching of layer V pyramidal neuron dendrites at P10 and P17 that recovered to normal by adulthood. Defects in DSCAM(del17) dendrite branching correlated with a temporal increase in apical branch spine density and lasting changes in spine morphology. At P15 and P42, mutant mice displayed a decrease in the percentage of large, stable spines and an increase in the percentage of small, immature spines. Together, our findings suggest that DSCAM contributes to pyramidal neuron morphogenesis by regulating dendrite arborization and spine formation during cortical circuit development.

  3. CD44: a novel synaptic cell adhesion molecule regulating structural and functional plasticity of dendritic spines

    PubMed Central

    Roszkowska, Matylda; Skupien, Anna; Wójtowicz, Tomasz; Konopka, Anna; Gorlewicz, Adam; Kisiel, Magdalena; Bekisz, Marek; Ruszczycki, Blazej; Dolezyczek, Hubert; Rejmak, Emilia; Knapska, Ewelina; Mozrzymas, Jerzy W.; Wlodarczyk, Jakub; Wilczynski, Grzegorz M.; Dzwonek, Joanna

    2016-01-01

    Synaptic cell adhesion molecules regulate signal transduction, synaptic function, and plasticity. However, their role in neuronal interactions with the extracellular matrix (ECM) is not well understood. Here we report that the CD44, a transmembrane receptor for hyaluronan, modulates synaptic plasticity. High-resolution ultrastructural analysis showed that CD44 was localized at mature synapses in the adult brain. The reduced expression of CD44 affected the synaptic excitatory transmission of primary hippocampal neurons, simultaneously modifying dendritic spine shape. The frequency of miniature excitatory postsynaptic currents decreased, accompanied by dendritic spine elongation and thinning. These structural and functional alterations went along with a decrease in the number of presynaptic Bassoon puncta, together with a reduction of PSD-95 levels at dendritic spines, suggesting a reduced number of functional synapses. Lack of CD44 also abrogated spine head enlargement upon neuronal stimulation. Moreover, our results indicate that CD44 contributes to proper dendritic spine shape and function by modulating the activity of actin cytoskeleton regulators, that is, Rho GTPases (RhoA, Rac1, and Cdc42). Thus CD44 appears to be a novel molecular player regulating functional and structural plasticity of dendritic spines. PMID:27798233

  4. VCP and ATL1 regulate endoplasmic reticulum and protein synthesis for dendritic spine formation

    PubMed Central

    Shih, Yu-Tzu; Hsueh, Yi-Ping

    2016-01-01

    Imbalanced protein homeostasis, such as excessive protein synthesis and protein aggregation, is a pathogenic hallmark of a range of neurological disorders. Here, using expression of mutant proteins, a knockdown approach and disease mutation knockin mice, we show that VCP (valosin-containing protein), together with its cofactor P47 and the endoplasmic reticulum (ER) morphology regulator ATL1 (Atlastin-1), regulates tubular ER formation and influences the efficiency of protein synthesis to control dendritic spine formation in neurons. Strengthening the significance of protein synthesis in dendritic spinogenesis, the translation blocker cyclohexamide and the mTOR inhibitor rapamycin reduce dendritic spine density, while a leucine supplement that increases protein synthesis ameliorates the dendritic spine defects caused by Vcp and Atl1 deficiencies. Because VCP and ATL1 are the causative genes of several neurodegenerative and neurodevelopmental disorders, we suggest that impaired ER formation and inefficient protein synthesis are significant in the pathogenesis of multiple neurological disorders. PMID:26984393

  5. VCP and ATL1 regulate endoplasmic reticulum and protein synthesis for dendritic spine formation.

    PubMed

    Shih, Yu-Tzu; Hsueh, Yi-Ping

    2016-03-17

    Imbalanced protein homeostasis, such as excessive protein synthesis and protein aggregation, is a pathogenic hallmark of a range of neurological disorders. Here, using expression of mutant proteins, a knockdown approach and disease mutation knockin mice, we show that VCP (valosin-containing protein), together with its cofactor P47 and the endoplasmic reticulum (ER) morphology regulator ATL1 (Atlastin-1), regulates tubular ER formation and influences the efficiency of protein synthesis to control dendritic spine formation in neurons. Strengthening the significance of protein synthesis in dendritic spinogenesis, the translation blocker cyclohexamide and the mTOR inhibitor rapamycin reduce dendritic spine density, while a leucine supplement that increases protein synthesis ameliorates the dendritic spine defects caused by Vcp and Atl1 deficiencies. Because VCP and ATL1 are the causative genes of several neurodegenerative and neurodevelopmental disorders, we suggest that impaired ER formation and inefficient protein synthesis are significant in the pathogenesis of multiple neurological disorders.

  6. Selective Estrogen Receptor Modulators Regulate Dendritic Spine Plasticity in the Hippocampus of Male Rats

    PubMed Central

    González-Burgos, Ignacio; Rivera-Cervantes, Martha C.; Velázquez-Zamora, Dulce A.; Feria-Velasco, Alfredo; Garcia-Segura, Luis Miguel

    2012-01-01

    Some selective estrogen receptor modulators, such as raloxifene and tamoxifen, are neuroprotective and reduce brain inflammation in several experimental models of neurodegeneration. In addition, raloxifene and tamoxifen counteract cognitive deficits caused by gonadal hormone deprivation in male rats. In this study, we have explored whether raloxifene and tamoxifen may regulate the number and geometry of dendritic spines in CA1 pyramidal neurons of the rat hippocampus. Young adult male rats were injected with raloxifene (1 mg/kg), tamoxifen (1 mg/kg), or vehicle and killed 24 h after the injection. Animals treated with raloxifene or tamoxifen showed an increased numerical density of dendritic spines in CA1 pyramidal neurons compared to animals treated with vehicle. Raloxifene and tamoxifen had also specific effects in the morphology of spines. These findings suggest that raloxifene and tamoxifen may influence the processing of information by hippocampal pyramidal neurons by affecting the number and shape of dendritic spines. PMID:22164341

  7. Brain-derived neurotrophic factor mediates estradiol-induced dendritic spine formation in hippocampal neurons.

    PubMed

    Murphy, D D; Cole, N B; Segal, M

    1998-09-15

    Dendritic spines are of major importance in information processing and memory formation in central neurons. Estradiol has been shown to induce an increase of dendritic spine density on hippocampal neurons in vivo and in vitro. The neurotrophin brain-derived neurotrophic factor (BDNF) recently has been implicated in neuronal maturation, plasticity, and regulation of GABAergic interneurons. We now demonstrate that estradiol down-regulates BDNF in cultured hippocampal neurons to 40% of control values within 24 hr of exposure. This, in turn, decreases inhibition and increases excitatory tone in pyramidal neurons, leading to a 2-fold increase in dendritic spine density. Exogenous BDNF blocks the effects of estradiol on spine formation, and BDNF depletion with a selective antisense oligonucleotide mimics the effects of estradiol. Addition of BDNF antibodies also increases spine density, and diazepam, which facilitates GABAergic neurotransmission, blocks estradiol-induced spine formation. These observations demonstrate a functional link between estradiol, BDNF as a potent regulator of GABAergic interneurons, and activity-dependent formation of dendritic spines in hippocampal neurons.

  8. Morphologic evidence for spatially clustered spines in apical dendrites of monkey neocortical pyramidal cells.

    PubMed

    Yadav, Aniruddha; Gao, Yuan Z; Rodriguez, Alfredo; Dickstein, Dara L; Wearne, Susan L; Luebke, Jennifer I; Hof, Patrick R; Weaver, Christina M

    2012-09-01

    The general organization of neocortical connectivity in rhesus monkey is relatively well understood. However, mounting evidence points to an organizing principle that involves clustered synapses at the level of individual dendrites. Several synaptic plasticity studies have reported cooperative interaction between neighboring synapses on a given dendritic branch, which may potentially induce synapse clusters. Additionally, theoretical models have predicted that such cooperativity is advantageous, in that it greatly enhances a neuron's computational repertoire. However, largely because of the lack of sufficient morphologic data, the existence of clustered synapses in neurons on a global scale has never been established. The majority of excitatory synapses are found within dendritic spines. In this study, we demonstrate that spine clusters do exist on pyramidal neurons by analyzing the three-dimensional locations of ∼40,000 spines on 280 apical dendritic branches in layer III of the rhesus monkey prefrontal cortex. By using clustering algorithms and Monte Carlo simulations, we quantify the probability that the observed extent of clustering does not occur randomly. This provides a measure that tests for spine clustering on a global scale, whenever high-resolution morphologic data are available. Here we demonstrate that spine clusters occur significantly more frequently than expected by pure chance and that spine clustering is concentrated in apical terminal branches. These findings indicate that spine clustering is driven by systematic biological processes. We also found that mushroom-shaped and stubby spines are predominant in clusters on dendritic segments that display prolific clustering, independently supporting a causal link between spine morphology and synaptic clustering.

  9. 3D Microfluidic model for evaluating immunotherapy efficacy by tracking dendritic cell behaviour toward tumor cells.

    PubMed

    Parlato, Stefania; De Ninno, Adele; Molfetta, Rosa; Toschi, Elena; Salerno, Debora; Mencattini, Arianna; Romagnoli, Giulia; Fragale, Alessandra; Roccazzello, Lorenzo; Buoncervello, Maria; Canini, Irene; Bentivegna, Enrico; Falchi, Mario; Bertani, Francesca Romana; Gerardino, Annamaria; Martinelli, Eugenio; Natale, Corrado; Paolini, Rossella; Businaro, Luca; Gabriele, Lucia

    2017-04-24

    Immunotherapy efficacy relies on the crosstalk within the tumor microenvironment between cancer and dendritic cells (DCs) resulting in the induction of a potent and effective antitumor response. DCs have the specific role of recognizing cancer cells, taking up tumor antigens (Ags) and then migrating to lymph nodes for Ag (cross)-presentation to naïve T cells. Interferon-α-conditioned DCs (IFN-DCs) exhibit marked phagocytic activity and the special ability of inducing Ag-specific T-cell response. Here, we have developed a novel microfluidic platform recreating tightly interconnected cancer and immune systems with specific 3D environmental properties, for tracking human DC behaviour toward tumor cells. By combining our microfluidic platform with advanced microscopy and a revised cell tracking analysis algorithm, it was possible to evaluate the guided efficient motion of IFN-DCs toward drug-treated cancer cells and the succeeding phagocytosis events. Overall, this platform allowed the dissection of IFN-DC-cancer cell interactions within 3D tumor spaces, with the discovery of major underlying factors such as CXCR4 involvement and underscored its potential as an innovative tool to assess the efficacy of immunotherapeutic approaches.

  10. EPSPs Measured in Proximal Dendritic Spines of Cortical Pyramidal Neurons123

    PubMed Central

    2016-01-01

    Abstract EPSPs occur when the neurotransmitter glutamate binds to postsynaptic receptors located on small pleomorphic membrane protrusions called dendritic spines. To transmit the synaptic signal, these potentials must travel through the spine neck and the dendritic tree to reach the soma. Due to their small size, the electrical behavior of spines and their ability to compartmentalize electrical signals has been very difficult to assess experimentally. In this study, we developed a method to perform simultaneous two-photon voltage-sensitive dye recording with two-photon glutamate uncaging in order to measure the characteristics (amplitude and duration) of uncaging-evoked EPSPs in single spines on the basal dendrites of L5 pyramidal neurons in acute brain slices from CD1 control mice. We were able to record uncaging-evoked spine potentials that resembled miniature EPSPs at the soma from a wide range of spine morphologies. In proximal spines, these potentials averaged 13.0 mV (range, 6.5–30.8 mV; N = 20) for an average somatic EPSP of 0.59 mV, whereas the mean attenuation ratio (spine/soma) was found to be 25.3. Durations of spine EPSP waveforms were found to be 11.7 ms on average. Modeling studies demonstrate the important role that spine neck resistance (Rneck) plays in spine EPSP amplitudes. Simulations used to estimate Rneck by fits to voltage-sensitive dye measurements produced a mean of 179 MΩ (range, 23–420 MΩ; N = 19). Independent measurements based on fluorescence recovery after photobleaching of a cytosolic dye from spines of the same population of neurons produced a mean Rneck estimate of 204 MΩ (range, 52–521 MΩ; N = 34). PMID:27257618

  11. Non-Ionotropic NMDA Receptor Signaling Drives Activity-Induced Dendritic Spine Shrinkage.

    PubMed

    Stein, Ivar S; Gray, John A; Zito, Karen

    2015-09-02

    The elimination of dendritic spine synapses is a critical step in the refinement of neuronal circuits during development of the cerebral cortex. Several studies have shown that activity-induced shrinkage and retraction of dendritic spines depend on activation of the NMDA-type glutamate receptor (NMDAR), which leads to influx of extracellular calcium ions and activation of calcium-dependent phosphatases that modify regulators of the spine cytoskeleton, suggesting that influx of extracellular calcium ions drives spine shrinkage. Intriguingly, a recent report revealed a novel non-ionotropic function of the NMDAR in the regulation of synaptic strength, which relies on glutamate binding but is independent of ion flux through the receptor (Nabavi et al., 2013). Here, we tested whether non-ionotropic NMDAR signaling could also play a role in driving structural plasticity of dendritic spines. Using two-photon glutamate uncaging and time-lapse imaging of rat hippocampal CA1 neurons, we show that low-frequency glutamatergic stimulation results in shrinkage of dendritic spines even in the presence of the NMDAR d-serine/glycine binding site antagonist 7-chlorokynurenic acid (7CK), which fully blocks NMDAR-mediated currents and Ca(2+) transients. Notably, application of 7CK or MK-801 also converts spine enlargement resulting from a high-frequency uncaging stimulus into spine shrinkage, demonstrating that strong Ca(2+) influx through the NMDAR normally overcomes a non-ionotropic shrinkage signal to drive spine growth. Our results support a model in which NMDAR signaling, independent of ion flux, drives structural shrinkage at spiny synapses. Dendritic spine elimination is vital for the refinement of neural circuits during development and has been linked to improvements in behavioral performance in the adult. Spine shrinkage and elimination have been widely accepted to depend on Ca(2+) influx through NMDA-type glutamate receptors (NMDARs) in conjunction with long-term depression

  12. Known-Component 3D-2D Registration for Image Guidance and Quality Assurance in Spine Surgery Pedicle Screw Placement

    PubMed Central

    Uneri, A.; Stayman, J. W.; De Silva, T.; Wang, A. S.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Wolinsky, J.-P.; Gokaslan, Z. L.; Siewerdsen, J. H.

    2015-01-01

    Purpose To extend the functionality of radiographic/fluoroscopic imaging systems already within standard spine surgery workflow to: 1) provide guidance of surgical device analogous to an external tracking system; and 2) provide intraoperative quality assurance (QA) of the surgical product. Methods Using fast, robust 3D-2D registration in combination with 3D models of known components (surgical devices), the 3D pose determination was solved to relate known components to 2D projection images and 3D preoperative CT in near-real-time. Exact and parametric models of the components were used as input to the algorithm to evaluate the effects of model fidelity. The proposed algorithm employs the covariance matrix adaptation evolution strategy (CMA-ES) to maximize gradient correlation (GC) between measured projections and simulated forward projections of components. Geometric accuracy was evaluated in a spine phantom in terms of target registration error at the tool tip (TREx), and angular deviation (TREϕ) from planned trajectory. Results Transpedicle surgical devices (probe tool and spine screws) were successfully guided with TREx <2 mm and TREϕ<0.5° given projection views separated by at least >30° (easily accommodated on a mobile C-arm). QA of the surgical product based on 3D-2D registration demonstrated the detection of pedicle screw breach with TREx <1 mm, demonstrating a trend of improved accuracy correlated to the fidelity of the component model employed. Conclusions 3D-2D registration combined with 3D models of known surgical components provides a novel method for near-real-time guidance and quality assurance using a mobile C-arm without external trackers or fiducial markers. Ongoing work includes determination of optimal views based on component shape and trajectory, improved robustness to anatomical deformation, and expanded preclinical testing in spine and intracranial surgeries. PMID:26028805

  13. Known-component 3D-2D registration for image guidance and quality assurance in spine surgery pedicle screw placement

    NASA Astrophysics Data System (ADS)

    Uneri, A.; Stayman, J. W.; De Silva, T.; Wang, A. S.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Wolinsky, J.-P.; Gokaslan, Z. L.; Siewerdsen, J. H.

    2015-03-01

    Purpose. To extend the functionality of radiographic / fluoroscopic imaging systems already within standard spine surgery workflow to: 1) provide guidance of surgical device analogous to an external tracking system; and 2) provide intraoperative quality assurance (QA) of the surgical product. Methods. Using fast, robust 3D-2D registration in combination with 3D models of known components (surgical devices), the 3D pose determination was solved to relate known components to 2D projection images and 3D preoperative CT in near-real-time. Exact and parametric models of the components were used as input to the algorithm to evaluate the effects of model fidelity. The proposed algorithm employs the covariance matrix adaptation evolution strategy (CMA-ES) to maximize gradient correlation (GC) between measured projections and simulated forward projections of components. Geometric accuracy was evaluated in a spine phantom in terms of target registration error at the tool tip (TREx), and angular deviation (TREΦ) from planned trajectory. Results. Transpedicle surgical devices (probe tool and spine screws) were successfully guided with TREx<2 mm and TREΦ <0.5° given projection views separated by at least >30° (easily accommodated on a mobile C-arm). QA of the surgical product based on 3D-2D registration demonstrated the detection of pedicle screw breach with TREx<1 mm, demonstrating a trend of improved accuracy correlated to the fidelity of the component model employed. Conclusions. 3D-2D registration combined with 3D models of known surgical components provides a novel method for near-real-time guidance and quality assurance using a mobile C-arm without external trackers or fiducial markers. Ongoing work includes determination of optimal views based on component shape and trajectory, improved robustness to anatomical deformation, and expanded preclinical testing in spine and intracranial surgeries.

  14. Lynx1 Limits Dendritic Spine Turnover in the Adult Visual Cortex.

    PubMed

    Sajo, Mari; Ellis-Davies, Graham; Morishita, Hirofumi

    2016-09-07

    Dendritic spine turnover becomes limited in the adult cerebral cortex. Identification of specific aspects of spine dynamics that can be unmasked in adulthood and its regulatory molecular mechanisms could provide novel therapeutic targets for inducing plasticity at both the functional and structural levels for robust recovery from brain disorders and injuries in adults. Lynx1, an endogenous inhibitor of nicotinic acetylcholine receptors, was previously shown to increase its expression in adulthood and thus to limit functional ocular dominance plasticity in adult primary visual cortex (V1). However, the role of this "brake" on spine dynamics is not known. We examined the contribution of Lynx1 on dendritic spine turnover before and after monocular deprivation (MD) in adult V1 with chronic in vivo imaging using two-photon microscopy and determined the spine turnover rate of apical dendrites of layer 5 (L5) and L2/3 pyramidal neurons in adult V1 of Lynx1 knock-out (KO) mice. We found that the deletion of Lynx1 doubled the baseline spine turnover rate, suggesting that the spine dynamics in the adult cortex is actively limited by the presence of Lynx1. After MD, adult Lynx1-KO mice selectively exhibit higher rate of spine loss with no difference in gain rate in L5 neurons compared with control wild-type counterparts, revealing a key signature of spine dynamics associated with robust functional plasticity in adult V1. Overall, Lynx1 could be a promising therapeutic target to induce not only functional, but also structural plasticity at the level of spine dynamics in the adult brain. Dendritic spine turnover becomes limited in the adult cortex. In mouse visual cortex, a premier model of experience-dependent plasticity, we found that the deletion of Lynx1, a nicotinic "brake" for functional plasticity, doubled the baseline spine turnover in adulthood, suggesting that the spine dynamics in the adult cortex is actively limited by Lynx1. After visual deprivation, spine loss

  15. Lynx1 Limits Dendritic Spine Turnover in the Adult Visual Cortex

    PubMed Central

    Sajo, Mari

    2016-01-01

    Dendritic spine turnover becomes limited in the adult cerebral cortex. Identification of specific aspects of spine dynamics that can be unmasked in adulthood and its regulatory molecular mechanisms could provide novel therapeutic targets for inducing plasticity at both the functional and structural levels for robust recovery from brain disorders and injuries in adults. Lynx1, an endogenous inhibitor of nicotinic acetylcholine receptors, was previously shown to increase its expression in adulthood and thus to limit functional ocular dominance plasticity in adult primary visual cortex (V1). However, the role of this “brake” on spine dynamics is not known. We examined the contribution of Lynx1 on dendritic spine turnover before and after monocular deprivation (MD) in adult V1 with chronic in vivo imaging using two-photon microscopy and determined the spine turnover rate of apical dendrites of layer 5 (L5) and L2/3 pyramidal neurons in adult V1 of Lynx1 knock-out (KO) mice. We found that the deletion of Lynx1 doubled the baseline spine turnover rate, suggesting that the spine dynamics in the adult cortex is actively limited by the presence of Lynx1. After MD, adult Lynx1-KO mice selectively exhibit higher rate of spine loss with no difference in gain rate in L5 neurons compared with control wild-type counterparts, revealing a key signature of spine dynamics associated with robust functional plasticity in adult V1. Overall, Lynx1 could be a promising therapeutic target to induce not only functional, but also structural plasticity at the level of spine dynamics in the adult brain. SIGNIFICANCE STATEMENT Dendritic spine turnover becomes limited in the adult cortex. In mouse visual cortex, a premier model of experience-dependent plasticity, we found that the deletion of Lynx1, a nicotinic “brake” for functional plasticity, doubled the baseline spine turnover in adulthood, suggesting that the spine dynamics in the adult cortex is actively limited by Lynx1. After

  16. Automated detection, 3D segmentation and analysis of high resolution spine MR images using statistical shape models

    NASA Astrophysics Data System (ADS)

    Neubert, A.; Fripp, J.; Engstrom, C.; Schwarz, R.; Lauer, L.; Salvado, O.; Crozier, S.

    2012-12-01

    Recent advances in high resolution magnetic resonance (MR) imaging of the spine provide a basis for the automated assessment of intervertebral disc (IVD) and vertebral body (VB) anatomy. High resolution three-dimensional (3D) morphological information contained in these images may be useful for early detection and monitoring of common spine disorders, such as disc degeneration. This work proposes an automated approach to extract the 3D segmentations of lumbar and thoracic IVDs and VBs from MR images using statistical shape analysis and registration of grey level intensity profiles. The algorithm was validated on a dataset of volumetric scans of the thoracolumbar spine of asymptomatic volunteers obtained on a 3T scanner using the relatively new 3D T2-weighted SPACE pulse sequence. Manual segmentations and expert radiological findings of early signs of disc degeneration were used in the validation. There was good agreement between manual and automated segmentation of the IVD and VB volumes with the mean Dice scores of 0.89 ± 0.04 and 0.91 ± 0.02 and mean absolute surface distances of 0.55 ± 0.18 mm and 0.67 ± 0.17 mm respectively. The method compares favourably to existing 3D MR segmentation techniques for VBs. This is the first time IVDs have been automatically segmented from 3D volumetric scans and shape parameters obtained were used in preliminary analyses to accurately classify (100% sensitivity, 98.3% specificity) disc abnormalities associated with early degenerative changes.

  17. Extracellular matrix control of dendritic spine and synapse structure and plasticity in adulthood

    PubMed Central

    Levy, Aaron D.; Omar, Mitchell H.; Koleske, Anthony J.

    2014-01-01

    Dendritic spines are the receptive contacts at most excitatory synapses in the central nervous system. Spines are dynamic in the developing brain, changing shape as they mature as well as appearing and disappearing as they make and break connections. Spines become much more stable in adulthood, and spine structure must be actively maintained to support established circuit function. At the same time, adult spines must retain some plasticity so their structure can be modified by activity and experience. As such, the regulation of spine stability and remodeling in the adult animal is critical for normal function, and disruption of these processes is associated with a variety of late onset diseases including schizophrenia and Alzheimer’s disease. The extracellular matrix (ECM), composed of a meshwork of proteins and proteoglycans, is a critical regulator of spine and synapse stability and plasticity. While the role of ECM receptors in spine regulation has been extensively studied, considerably less research has focused directly on the role of specific ECM ligands. Here, we review the evidence for a role of several brain ECM ligands and remodeling proteases in the regulation of dendritic spine and synapse formation, plasticity, and stability in adults. PMID:25368556

  18. Dietary cholesterol concentration affects synaptic plasticity and dendrite spine morphology of rabbit hippocampal neurons.

    PubMed

    Wang, Desheng; Zheng, Wen

    2015-10-05

    Previous studies have shown dietary cholesterol can enhance learning but retard memory which may be partly due to increased cholesterol levels in hippocampus and reduced afterhyperpolarization (AHP) amplitude of hippocampal CA1 neurons. This study explored the dose-dependent effect of dietary cholesterol on synaptic plasticity of rabbit hippocampal CA1 neurons and spine morphology, the postsynaptic structures responsible for synaptic plasticity. Field potential recordings revealed a low concentration of dietary cholesterol increased long-term potentiation (LTP) expression while high concentrations produced a pronounced reduction in LTP expression. Dietary cholesterol facilitated basal synaptic transmission but did not influence presynaptic function. DiI staining showed dietary cholesterol induced alterations in dendrite spine morphology characterized by increased mushroom spine density and decreased thin spine density, two kinds of dendritic spines that may be linked to memory consolidation and learning acquisition. Dietary cholesterol also modulated the geometric measures of mushroom spines. Therefore, dietary cholesterol dose-dependently modulated both synaptic plasticity and dendrite spine morphologies of hippocampal CA1 neurons that could mediate learning and memory changes previously seen to result from feeding a cholesterol diet.

  19. Sleep promotes branch-specific formation of dendritic spines after learning.

    PubMed

    Yang, Guang; Lai, Cora Sau Wan; Cichon, Joseph; Ma, Lei; Li, Wei; Gan, Wen-Biao

    2014-06-06

    How sleep helps learning and memory remains unknown. We report in mouse motor cortex that sleep after motor learning promotes the formation of postsynaptic dendritic spines on a subset of branches of individual layer V pyramidal neurons. New spines are formed on different sets of dendritic branches in response to different learning tasks and are protected from being eliminated when multiple tasks are learned. Neurons activated during learning of a motor task are reactivated during subsequent non-rapid eye movement sleep, and disrupting this neuronal reactivation prevents branch-specific spine formation. These findings indicate that sleep has a key role in promoting learning-dependent synapse formation and maintenance on selected dendritic branches, which contribute to memory storage.

  20. A critical role for myosin IIb in dendritic spine morphology and synaptic function.

    PubMed

    Ryu, Jubin; Liu, Lidong; Wong, Tak Pan; Wu, Dong Chuan; Burette, Alain; Weinberg, Richard; Wang, Yu Tian; Sheng, Morgan

    2006-01-19

    Dendritic spines show rapid motility and plastic morphology, which may mediate information storage in the brain. It is presently believed that polymerization/depolymerization of actin is the primary determinant of spine motility and morphogenesis. Here, we show that myosin IIB, a molecular motor that binds and contracts actin filaments, is essential for normal spine morphology and dynamics and represents a distinct biophysical pathway to control spine size and shape. Myosin IIB is enriched in the postsynaptic density (PSD) of neurons. Pharmacologic or genetic inhibition of myosin IIB alters protrusive motility of spines, destabilizes their classical mushroom-head morphology, and impairs excitatory synaptic transmission. Thus, the structure and function of spines is regulated by an actin-based motor in addition to the polymerization state of actin.

  1. Maternal Loss of Ube3a Impairs Experience-Driven Dendritic Spine Maintenance in the Developing Visual Cortex.

    PubMed

    Kim, Hyojin; Kunz, Portia A; Mooney, Richard; Philpot, Benjamin D; Smith, Spencer L

    2016-04-27

    Dendritic spines are a morphological feature of the majority of excitatory synapses in the mammalian neocortex and are motile structures with shapes and lifetimes that change throughout development. Proper cortical development and function, including cortical contributions to learning and memory formation, require appropriate experience-dependent dendritic spine remodeling. Dendritic spine abnormalities have been reported for many neurodevelopmental disorders, including Angelman syndrome (AS), which is caused by the loss of the maternally inherited UBE3A allele (encoding ubiquitin protein ligase E3A). Prior studies revealed that UBE3A protein loss leads to reductions in dendritic spine density and diminished excitatory synaptic transmission. However, the decrease in spine density could come from either a reduction in spine formation or an increase in spine elimination. Here, we used acute and longitudinal in vivo two-photon microscopy to investigate developmental and experience-dependent changes in the numbers, dynamics, and morphology of layer 5 pyramidal neuron apical dendritic spines in the primary visual cortex of control and AS model mice (Ube3a(m-/p+) mice). We found that neurons in AS model mice undergo a greater elimination of dendritic spines than wild-type mice during the end of the first postnatal month. However, when raised in darkness, spine density and dynamics were indistinguishable between control and AS model mice, which indicates that decreased spine density in AS model mice reflects impaired experience-driven spine maintenance. Our data thus demonstrate an experience-dependent anatomical substrate by which the loss of UBE3A reduces dendritic spine density and disrupts cortical circuitry. Reduced dendritic spine densities are common in the neurodevelopmental disorder Angelman syndrome (AS). Because prior reports were based on postmortem tissue, it was unknown whether this anatomical deficit arises from decreased spine formation and/or increased

  2. Travelling waves in a model of quasi-active dendrites with active spines

    NASA Astrophysics Data System (ADS)

    Timofeeva, Y.

    2010-05-01

    Dendrites, the major components of neurons, have many different types of branching structures and are involved in receiving and integrating thousands of synaptic inputs from other neurons. Dendritic spines with excitable channels can be present in large densities on the dendrites of many cells. The recently proposed Spike-Diffuse-Spike (SDS) model that is described by a system of point hot-spots (with an integrate-and-fire process) embedded throughout a passive tree has been shown to provide a reasonable caricature of a dendritic tree with supra-threshold dynamics. Interestingly, real dendrites equipped with voltage-gated ion channels can exhibit not only supra-threshold responses, but also sub-threshold dynamics. This sub-threshold resonant-like oscillatory behaviour has already been shown to be adequately described by a quasi-active membrane. In this paper we introduce a mathematical model of a branched dendritic tree based upon a generalisation of the SDS model where the active spines are assumed to be distributed along a quasi-active dendritic structure. We demonstrate how solitary and periodic travelling wave solutions can be constructed for both continuous and discrete spine distributions. In both cases the speed of such waves is calculated as a function of system parameters. We also illustrate that the model can be naturally generalised to an arbitrary branched dendritic geometry whilst remaining computationally simple. The spatio-temporal patterns of neuronal activity are shown to be significantly influenced by the properties of the quasi-active membrane. Active (sub- and supra-threshold) properties of dendrites are known to vary considerably among cell types and animal species, and this theoretical framework can be used in studying the combined role of complex dendritic morphologies and active conductances in rich neuronal dynamics.

  3. Dendritic spine classification using shape and appearance features based on two-photon microscopy.

    PubMed

    Ghani, Muhammad Usman; Mesadi, Fitsum; Kanık, Sümeyra Demir; Argunşah, Ali Özgür; Hobbiss, Anna Felicity; Israely, Inbal; Ünay, Devrim; Taşdizen, Tolga; Çetin, Müjdat

    2017-03-01

    Neuronal morphology and function are highly coupled. In particular, dendritic spine morphology is strongly governed by the incoming neuronal activity. The first step towards understanding the structure-function relationships is to classify spine shapes into the main spine types suggested in the literature. Due to the lack of reliable automated analysis tools, classification is mostly performed manually, which is a time-intensive task and prone to subjectivity. We propose an automated method to classify dendritic spines using shape and appearance features based on challenging two-photon laser scanning microscopy (2PLSM) data. Disjunctive Normal Shape Models (DNSM) is a recently proposed parametric shape representation. We perform segmentation of spine images by applying DNSM and use the resulting representation as shape features. Furthermore, we use Histogram of oriented gradients (HOG) to extract appearance features. In this context, we propose a kernel density estimation (KDE) based framework for dendritic spine classification, which uses these shape and appearance features. Our shape and appearance features based approach combined with Neural Network (NN) correctly classifies 87.06% of spines on a dataset of 456 spines. Our proposed method outperforms standard morphological feature based approaches. Our KDE based framework also enables neuroscientists to analyze the separability of spine shape classes in the likelihood ratio space, which leads to further insights about nature of the spine shape analysis problem. Results validate that performance of our proposed approach is comparable to a human expert. It also enable neuroscientists to study shape statistics in the likelihood ratio space. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Control of Spine Maturation and Pruning through ProBDNF Synthesized and Released in Dendrites

    PubMed Central

    Orefice, Lauren L.; Shih, Chien-Cheng; Xu, Haifei; Waterhouse, Emily G.; Xu, Baoji

    2015-01-01

    Excess synapses formed during early postnatal development are pruned over an extended period, while the remaining synapses mature. Synapse pruning is critical for activity-dependent refinement of neuronal connections and its dysregulation has been found in neurodevelopmental disorders such as autism spectrum disorders; however, the mechanism underlying synapse pruning remains largely unknown. As dendritic spines are the postsynaptic sites for the vast majority of excitatory synapses, spine maturation and pruning are indicators for maturation and elimination of these synapses. Our previous studies have found that dendritically localized mRNA for brain-derived neurotrophic factor (BDNF) regulates spine maturation and pruning. Here we investigated the mechanism by which dendritic Bdnf mRNA, but not somatically restricted Bdnf mRNA, promotes spine maturation and pruning. We found that neuronal activity stimulates both translation of dendritic Bdnf mRNA and secretion of its translation product mainly as proBDNF. The secreted proBDNF promotes spine maturation and pruning, and its effect on spine pruning is in part mediated by the p75NTR receptor via RhoA activation. Furthermore, some proBDNF is extracellularly converted to mature BDNF and then promotes maturation of stimulated spines by activating Rac1 through the TrkB receptor. In contrast, translation of somatic Bdnf mRNA and the release of its translation product mainly as mature BDNF are independent of action potentials. These results not only reveal a biochemical pathway regulating synapse pruning, but also suggest that BDNF synthesized in the soma and dendrites is released through distinct secretory pathways. PMID:26705735

  5. Neural Cell Adhesion Molecule NrCAM Regulates Semaphorin 3F-Induced Dendritic Spine Remodeling

    PubMed Central

    Demyanenko, Galina P.; Mohan, Vishwa; Zhang, Xuying; Brennaman, Leann H.; Dharbal, Katherine E.S.; Tran, Tracy S.; Manis, Paul B.

    2014-01-01

    Neuron-glial related cell adhesion molecule (NrCAM) is a regulator of axon growth and repellent guidance, and has been implicated in autism spectrum disorders. Here a novel postsynaptic role for NrCAM in Semaphorin3F (Sema3F)-induced dendritic spine remodeling was identified in pyramidal neurons of the primary visual cortex (V1). NrCAM localized to dendritic spines of star pyramidal cells in postnatal V1, where it was coexpressed with Sema3F. NrCAM deletion in mice resulted in elevated spine densities on apical dendrites of star pyramidal cells at both postnatal and adult stages, and electron microscopy revealed increased numbers of asymmetric synapses in layer 4 of V1. Whole-cell recordings in cortical slices from NrCAM-null mice revealed increased frequency of mEPSCs in star pyramidal neurons. Recombinant Sema3F-Fc protein induced spine retraction on apical dendrites of wild-type, but not NrCAM-null cortical neurons in culture, while re-expression of NrCAM rescued the spine retraction response. NrCAM formed a complex in brain with Sema3F receptor subunits Neuropilin-2 (Npn-2) and PlexinA3 (PlexA3) through an Npn-2-binding sequence (TARNER) in the extracellular Ig1 domain. A trans heterozygous genetic interaction test demonstrated that Sema3F and NrCAM pathways interacted in vivo to regulate spine density in star pyramidal neurons. These findings reveal NrCAM as a novel postnatal regulator of dendritic spine density in cortical pyramidal neurons, and an integral component of the Sema3F receptor complex. The results implicate NrCAM as a contributor to excitatory/inhibitory balance in neocortical circuits. PMID:25143608

  6. Ovarian Steroids Increase PSD-95 Expression and Dendritic Spines in the Dorsal Raphe of Ovariectomized Macaques

    PubMed Central

    Rivera, Heidi M.; Bethea, Cynthia L.

    2014-01-01

    Estradiol (E) and progesterone (P) promote spinogenesis in several brain areas. Intracellular signaling cascades that promote spinogenesis involve RhoGTPases, glutamate signaling and synapse assembly. We found that in serotonin neurons, E±P administration increases (a) gene and protein expression of RhoGTPases, (b) gene expression of glutamate receptors (c) gene expression of pivotal synapse assembly proteins. Therefore, in this study we determined whether structural changes in dendritic spines in the dorsal raphe follow the observed changes in gene and protein expression. Dendritic spines were examined with immunogold silver staining of a spine marker protein, postsynaptic density-95 (PSD-95) and with Golgi staining. In the PSD-95 study, adult Ovx monkeys received placebo, E, P, or E+P for 1 month (n=3/group). Sections were immunostained for PSD-95 and the number of PSD-95-positive puncta was determined with stereology. E, P and E+P treatment significantly increased the total number of PSD-95-positive puncta (ANOVA, P=0.04). In the Golgi study, adult Ovx monkeys received placebo, E or E+P for 1 month (n=3–4) and the midbrain was Golgi-stained. A total of 80 neurons were analyzed with Neurolucida software. There was a significant difference in spine density that depended on branch order (two-way ANOVA). E+P treatment significantly increased spine density in higher-order (3–5°) dendritic branches relative to Ovx group (Bonferroni, P<0.05). In summary, E+P leads to the elaboration of dendritic spines on dorsal raphe neurons. The ability of E to induce PSD-95, but not actual spines, suggests either a sampling or time lag issue. Increased spinogenesis on serotonin dendrites would facilitate excitatory glutamatergic input and, in turn, increase serotonin neurotransmission throughout the brain. PMID:23959764

  7. Ovarian steroids increase PSD-95 expression and dendritic spines in the dorsal raphe of ovariectomized macaques.

    PubMed

    Rivera, Heidi M; Bethea, Cynthia L

    2013-12-01

    Estradiol (E) and progesterone (P) promote spinogenesis in several brain areas. Intracellular signaling cascades that promote spinogenesis involve RhoGTPases, glutamate signaling and synapse assembly. We found that in serotonin neurons, E ± P administration increases (a) gene and protein expression of RhoGTPases, (b) gene expression of glutamate receptors, and (c) gene expression of pivotal synapse assembly proteins. Therefore, in this study we determined whether structural changes in dendritic spines in the dorsal raphe follow the observed changes in gene and protein expression. Dendritic spines were examined with immunogold silver staining of a spine marker protein, postsynaptic density-95 (PSD-95) and with Golgi staining. In the PSD-95 study, adult Ovx monkeys received placebo, E, P, or E + P for 1 month (n = 3/group). Sections were immunostained for PSD-95 and the number of PSD-95-positive puncta was determined with stereology. E, P, and E + P treatment significantly increased the total number of PSD-95-positive puncta (ANOVA, P = 0.04). In the golgi study, adult Ovx monkeys received placebo, E or E + P for 1 month (n = 3-4) and the midbrain was golgi-stained. A total of 80 neurons were analyzed with Neurolucida software. There was a significant difference in spine density that depended on branch order (two-way ANOVA). E + P treatment significantly increased spine density in higher-order (3°-5°) dendritic branches relative to Ovx group (Bonferroni, P < 0.05). In summary, E + P leads to the elaboration of dendritic spines on dorsal raphe neurons. The ability of E to induce PSD-95, but not actual spines, suggests either a sampling or time lag issue. Increased spinogenesis on serotonin dendrites would facilitate excitatory glutamatergic input and, in turn, increase serotonin neurotransmission throughout the brain. Copyright © 2013 Wiley Periodicals, Inc.

  8. Pathogenic SYNGAP1 mutations impair cognitive development by disrupting maturation of dendritic spine synapses.

    PubMed

    Clement, James P; Aceti, Massimiliano; Creson, Thomas K; Ozkan, Emin D; Shi, Yulin; Reish, Nicholas J; Almonte, Antoine G; Miller, Brooke H; Wiltgen, Brian J; Miller, Courtney A; Xu, Xiangmin; Rumbaugh, Gavin

    2012-11-09

    Mutations that cause intellectual disability (ID) and autism spectrum disorder (ASD) are commonly found in genes that encode for synaptic proteins. However, it remains unclear how mutations that disrupt synapse function impact intellectual ability. In the SYNGAP1 mouse model of ID/ASD, we found that dendritic spine synapses develop prematurely during the early postnatal period. Premature spine maturation dramatically enhanced excitability in the developing hippocampus, which corresponded with the emergence of behavioral abnormalities. Inducing SYNGAP1 mutations after critical developmental windows closed had minimal impact on spine synapse function, whereas repairing these pathogenic mutations in adulthood did not improve behavior and cognition. These data demonstrate that SynGAP protein acts as a critical developmental repressor of neural excitability that promotes the development of life-long cognitive abilities. We propose that the pace of dendritic spine synapse maturation in early life is a critical determinant of normal intellectual development.

  9. Pathogenic SYNGAP1 mutations impair cognitive development by disrupting the maturation of dendritic spine synapses

    PubMed Central

    Clement, James P.; Aceti, Massimiliano; Creson, Thomas K.; Ozkan, Emin D.; Shi, Yulin; Reish, Nicholas J.; Almonte, Antoine G.; Miller, Brooke H.; Wiltgen, Brian J.; Miller, Courtney A.; Xu, Xiangmin; Rumbaugh, Gavin

    2012-01-01

    SUMMARY Mutations that cause Intellectual Disability (ID) and Autism Spectrum Disorder (ASD) are commonly found in genes that encode for synaptic proteins. However, it remains unclear how mutations that disrupt synapse function impact intellectual ability. In the SYNGAP1 mouse model of ID/ASD, we found that dendritic spine synapses develop prematurely during the early postnatal period. Premature spine maturation dramatically enhanced excitability in the developing hippocampus, which corresponded with the emergence of behavioral abnormalities. Inducing SYNGAP1 mutations after critical developmental windows closed had minimal impact on spine synapse function, while repairing these pathogenic mutations in adulthood did not improve behavior and cognition. These data demonstrate that SynGAP protein acts as a critical developmental repressor of neural excitability that promotes the development of life-long cognitive abilities. We propose that the pace of dendritic spine synapse maturation in early life is a critical determinant of normal intellectual development. PMID:23141534

  10. Voxel-based morphometry predicts shifts in dendritic spine density and morphology with auditory fear conditioning.

    PubMed

    Keifer, O P; Hurt, R C; Gutman, D A; Keilholz, S D; Gourley, S L; Ressler, K J

    2015-07-07

    Neuroimaging has provided compelling data about the brain. Yet the underlying mechanisms of many neuroimaging techniques have not been elucidated. Here we report a voxel-based morphometry (VBM) study of Thy1-YFP mice following auditory fear conditioning complemented by confocal microscopy analysis of cortical thickness, neuronal morphometric features and nuclei size/density. Significant VBM results included the nuclei of the amygdala, the insula and the auditory cortex. There were no significant VBM changes in a control brain area. Focusing on the auditory cortex, confocal analysis showed that fear conditioning led to a significantly increased density of shorter and wider dendritic spines, while there were no spine differences in the control area. Of all the morphology metrics studied, the spine density was the only one to show significant correlation with the VBM signal. These data demonstrate that learning-induced structural changes detected by VBM may be partially explained by increases in dendritic spine density.

  11. Dlg5 Regulates Dendritic Spine Formation and Synaptogenesis by Controlling Subcellular N-Cadherin Localization

    PubMed Central

    Wang, Shih-Hsiu J.; Celic, Ivana; Choi, Se-Young; Riccomagno, Martin; Wang, Qiang; Sun, Lu O.; Mitchell, Sarah P.; Vasioukhin, Valera; Huganir, Richard L.

    2014-01-01

    Most excitatory synapses in the mammalian brain are formed on dendritic spines, and spine density has a profound impact on synaptic transmission, integration, and plasticity. Membrane-associated guanylate kinase (MAGUK) proteins are intracellular scaffolding proteins with well established roles in synapse function. However, whether MAGUK proteins are required for the formation of dendritic spines in vivo is unclear. We isolated a novel disc large-5 (Dlg5) allele in mice, Dlg5LP, which harbors a missense mutation in the DLG5 SH3 domain, greatly attenuating its ability to interact with the DLG5 GUK domain. We show here that DLG5 is a MAGUK protein that regulates spine formation, synaptogenesis, and synaptic transmission in cortical neurons. DLG5 regulates synaptogenesis by enhancing the cell surface localization of N-cadherin, revealing a key molecular mechanism for regulating the subcellular localization of this cell adhesion molecule during synaptogenesis. PMID:25232112

  12. Golgi-independent secretory trafficking through recycling endosomes in neuronal dendrites and spines

    PubMed Central

    Bowen, Aaron B; Bourke, Ashley M; Hiester, Brian G; Hanus, Cyril

    2017-01-01

    Neurons face the challenge of regulating the abundance, distribution and repertoire of integral membrane proteins within their immense, architecturally complex dendritic arbors. While the endoplasmic reticulum (ER) supports dendritic translation, most dendrites lack the Golgi apparatus (GA), an essential organelle for conventional secretory trafficking. Thus, whether secretory cargo is locally trafficked in dendrites through a non-canonical pathway remains a fundamental question. Here we define the dendritic trafficking itinerary for key synaptic molecules in rat cortical neurons. Following ER exit, the AMPA-type glutamate receptor GluA1 and neuroligin 1 undergo spatially restricted entry into the dendritic secretory pathway and accumulate in recycling endosomes (REs) located in dendrites and spines before reaching the plasma membrane. Surprisingly, GluA1 surface delivery occurred even when GA function was disrupted. Thus, in addition to their canonical role in protein recycling, REs also mediate forward secretory trafficking in neuronal dendrites and spines through a specialized GA-independent trafficking network. PMID:28875935

  13. Fluorescence imaging of dendritic spines of Golgi-Cox-stained neurons using brightening background

    NASA Astrophysics Data System (ADS)

    Ai, Min; Xiong, Hanqing; Yang, Tao; Shang, Zhenhua; Chen, Muqing; Liu, Xiuli; Zeng, Shaoqun

    2015-01-01

    We report a novel fluorescence imaging approach to imaging nonfluorescence-labeled biological tissue samples. The method was demonstrated by imaging neurons in Golgi-Cox-stained and epoxy-resin-embedded samples through the excitation of the background fluorescence of the specimens. The dark neurons stood out clearly against background fluorescence in the images, enabling the tracing of a single dendritic spine using both confocal and wide-field fluorescence microscopy. The results suggest that the reported fluorescence imaging method would provide an effective alternative solution to image nonfluorescence-labeled samples, and it allows tracing the dendritic spine structure of neurons.

  14. Effects of lead exposure on dendrite and spine development in hippocampal dentate gyrus areas of rats.

    PubMed

    Hu, Fan; Ge, Meng-Meng; Chen, Wei-Heng

    2016-03-01

    Lead exposure has been implicated in the impairment of synaptic plasticity in the hippocampal dentate gyrus (DG) areas of rats. However, whether the degradation of physiological properties is based on the morphological alteration of granule neurons in DG areas remains elusive. Here, we examined the dendritic branch extension and spine formation of granule neurons after lead exposure during development in rats. Dendritic morphology was studied using Golgi-Cox stain method, which was followed by Sholl analysis at postnatal days 14 and 21. Our results indicated that, for both ages, lead exposure significantly decreased the total dendritic length and spine density of granule neurons in the DG of the rat hippocampus. Further branch order analysis revealed that the decrease of dendritic length was observed only at the second branch order. Moreover, there were obvious deficits in the proportion and size of mushroom-type spines. These deficits in spine formation and maturity were accompanied by a decrease in Arc/Arg3.1 expression. Our present findings are the first to show that developmental lead exposure disturbs branch and spine formation in hippocampal DG areas. Arc/Arg3.1 may have a critical role in the disruption of neuronal morphology and synaptic plasticity in lead-exposed rats.

  15. Aluminum chloride induces neuroinflammation, loss of neuronal dendritic spine and cognition impairment in developing rat.

    PubMed

    Cao, Zheng; Yang, Xu; Zhang, Haiyang; Wang, Haoran; Huang, Wanyue; Xu, Feibo; Zhuang, Cuicui; Wang, Xiaoguang; Li, Yanfei

    2016-05-01

    Aluminum (Al) is present in the daily life of humans, and the incidence of Al contamination increased in recent years. Long-term excessive Al intake induces neuroinflammation and cognition impairment. Neuroinflammation alter density of dendritic spine, which, in turn, influence cognition function. However, it is unknown whether increased neuroinflammation is associated with altered density of dendritic spine in Al-treated rats. In the present study, AlCl3 was orally administrated to rat at 50, 150 and 450 mg/kg for 90d. We examined the effects of AlCl3 on the cognition function, density of dendritic spine in hippocampus of CA1 and DG region and the mRNA levels of IL-1β, IL-6, TNF-α, MHC II, CX3CL1 and BNDF in developing rat. These results showed exposure to AlCl3 lead to increased mRNA levels of IL-1β, IL-6, TNF-α and MCH II, decreased mRNA levels of CX3CL1 and BDNF, decreased density of dendritic spine and impaired learning and memory in developing rat. Our results suggest AlCl3 can induce neuroinflammation that may result in loss of spine, and thereby leads to learning and memory deficits.

  16. Emerging Roles of Filopodia and Dendritic Spines in Motoneuron Plasticity during Development and Disease

    PubMed Central

    Kanjhan, Refik; Noakes, Peter G.; Bellingham, Mark C.

    2016-01-01

    Motoneurons develop extensive dendritic trees for receiving excitatory and inhibitory synaptic inputs to perform a variety of complex motor tasks. At birth, the somatodendritic domains of mouse hypoglossal and lumbar motoneurons have dense filopodia and spines. Consistent with Vaughn's synaptotropic hypothesis, we propose a developmental unified-hybrid model implicating filopodia in motoneuron spinogenesis/synaptogenesis and dendritic growth and branching critical for circuit formation and synaptic plasticity at embryonic/prenatal/neonatal period. Filopodia density decreases and spine density initially increases until postnatal day 15 (P15) and then decreases by P30. Spine distribution shifts towards the distal dendrites, and spines become shorter (stubby), coinciding with decreases in frequency and increases in amplitude of excitatory postsynaptic currents with maturation. In transgenic mice, either overexpressing the mutated human Cu/Zn-superoxide dismutase (hSOD1G93A) gene or deficient in GABAergic/glycinergic synaptic transmission (gephyrin, GAD-67, or VGAT gene knockout), hypoglossal motoneurons develop excitatory glutamatergic synaptic hyperactivity. Functional synaptic hyperactivity is associated with increased dendritic growth, branching, and increased spine and filopodia density, involving actin-based cytoskeletal and structural remodelling. Energy-dependent ionic pumps that maintain intracellular sodium/calcium homeostasis are chronically challenged by activity and selectively overwhelmed by hyperactivity which eventually causes sustained membrane depolarization leading to excitotoxicity, activating microglia to phagocytose degenerating neurons under neuropathological conditions. PMID:26843990

  17. Super-Resolution Dynamic Imaging of Dendritic Spines Using a Low-Affinity Photoconvertible Actin Probe

    PubMed Central

    Lelek, Mickaël; Darzacq, Xavier; Triller, Antoine; Zimmer, Christophe; Dahan, Maxime

    2011-01-01

    The actin cytoskeleton of dendritic spines plays a key role in morphological aspects of synaptic plasticity. The detailed analysis of the spine structure and dynamics in live neurons, however, has been hampered by the diffraction-limited resolution of conventional fluorescence microscopy. The advent of nanoscopic imaging techniques thus holds great promise for the study of these processes. We implemented a strategy for the visualization of morphological changes of dendritic spines over tens of minutes at a lateral resolution of 25 to 65 nm. We have generated a low-affinity photoconvertible probe, capable of reversibly binding to actin and thus allowing long-term photoactivated localization microscopy of the spine cytoskeleton. Using this approach, we resolve structural parameters of spines and record their long-term dynamics at a temporal resolution below one minute. Furthermore, we have determined changes in the spine morphology in response to pharmacologically induced synaptic activity and quantified the actin redistribution underlying these changes. By combining PALM imaging with quantum dot tracking, we could also simultaneously visualize the cytoskeleton and the spine membrane, allowing us to record complementary information on the morphological changes of the spines at super-resolution. PMID:21264214

  18. Motherhood and the hormones of pregnancy modify concentrations of hippocampal neuronal dendritic spines.

    PubMed

    Kinsley, Craig H; Trainer, Regina; Stafisso-Sandoz, Graciela; Quadros, Princy; Marcus, Lori Keyser; Hearon, Christa; Meyer, Elizabeth Ann Amory; Hester, Naomi; Morgan, Melissa; Kozub, Frederick J; Lambert, Kelly G

    2006-02-01

    Short-term fluctuations in steroid hormones such as estradiol (E2) and progesterone (P) can affect the concentration of hippocampal dendritic spines in adult, cycling nulliparous female rats. Pregnancy is characterized by a significantly longer duration of substantially elevated E2 and P compared to the estrous cycle. Thus, even greater changes than those reported during estrus may be evident. In two experiments, we examined the extent to which reproductive and hormonal state altered the concentration of apical neuronal dendritic spines of the CA1 region of the hippocampus in the following age-matched groups (N's = 7-10/group) of rats: in Exp. 1., CA1 dendritic spine density was examined in nulliparous diestrus (DES), proestrus (PRO), and estrus (ES) females, and late-pregnant (LP) (day 21) and lactating (day 5-6; LACT) females. In Exp. 2, the effects on spine density of a regimen mimicking pregnancy (and that stimulates maternal behavior) were examined, using ovariectomized, no hormone-exposed (OVX-minus) vs. sequential P&E(2)-treated (OVX + P&E2) groups. For both experiments, brains were removed, Golgi-Cox-stained and the most lateral tertiary branches of the apical dendrite of completely-stained hippocampal CA1 pyramidal neurons were traced with oil-immersion at x 1600 and dendritic spine density (# spines/10 micro dendritic segment) recorded. In Exp. 1, spine density was increased in LP and LACT females (which were not different) compared to the other virgin groups, including PRO females, who had more spines than DES and ES. In Exp. 2, OVX + P&E2 displayed significantly more dendritic spines per 10 micro than OVX-minus females (and had numbers that were similar to those of LP and LACT from Exp. 1). Pregnancy and its attendant hormonal fluctuations, therefore, may alter hippocampal neurons that regulate some non-pup-directed components of maternal behavior (e.g., nest building) or behaviors that support maternal behavior (e.g., foraging, associative memory).

  19. POST-PUBERTAL DECREASE IN HIPPOCAMPAL DENDRITIC SPINES OF FEMALE RATS

    PubMed Central

    Yildirim, Murat; Mapp, Oni M.; Janssen, William G.M.; Yin, Weiling; Morrison, John H.; Gore, Andrea C.

    2011-01-01

    Hippocampal dendritic spine and synapse numbers in female rats vary across the estrous cycle and following experimental manipulation of hormone levels in adulthood. Based on behavioral studies demonstrating that learning patterns are altered following puberty, we hypothesized that dendritic spine number in rat hippocampal CA1 region would change post-pubertally. Female Sprague-Dawley rats were divided into prepubertal (postnatal day (P) 22), peripubertal (P35) and post-pubertal (P49) groups, with the progression of puberty evaluated by vaginal opening, and estrous cyclicity subsequently assessed by daily vaginal smears. Spinophilin immunoreactivity in dendritic spines was used as an index of spinogenesis in area CA1 stratum radiatum (CA1sr) of hippocampus. First, electron microscopy analyses confirmed the presence of spinophilin specifically in dendritic spines of CA1sr, supporting spinophilin as a reliable marker of hippocampal spines in young female rats. Second, stereologic analysis was performed to assess the total number of spinophilin-immunoreactive puncta (i.e. spines) and CA1sr volume in developing rats. Our results indicated that the number of spinophilin-immunoreactive spines in CA1sr was decreased 46% in the post-pubertal group compared to the two younger groups, whereas the volume of the hippocampus underwent an overall increase during this same developmental time frame. Third, to determine a potential role of estradiol in this process, an additional group of rats was ovariectomized (OVX) prepubertally at P22, then treated with estradiol or vehicle at P35, and spinophilin quantified as above in rats perfused on P49. No difference in spinophilin puncta number was found in OVX rats between the two hormone groups, suggesting that this developmental decrease is independent of peripheral estradiol. These changes in spine density coincident with puberty may be related to altered hippocampal plasticity and synaptic consolidation at this phase of maturity. PMID

  20. Extinction procedure induces pruning of dendritic spines in CA1 hippocampal field depending on strength of training in rats

    PubMed Central

    Garín-Aguilar, María E.; Díaz-Cintra, Sofía; Quirarte, Gina L.; Aguilar-Vázquez, Azucena; Medina, Andrea C.; Prado-Alcalá, Roberto A.

    2012-01-01

    Numerous reports indicate that learning and memory of conditioned responses are accompanied by genesis of dendritic spines in the hippocampus, although there is a conspicuous lack of information regarding spine modifications after behavioral extinction. There is ample evidence that treatments that typically produce amnesia become innocuous when animals are submitted to a procedure of enhanced training. We now report that extinction of inhibitory avoidance (IA), trained with relatively low foot-shock intensities, induces pruning of dendritic spines along the length of the apical dendrites of hippocampal CA1 neurons. When animals are trained with a relatively high foot-shock there is a high resistance to extinction, and pruning in the proximal and medial segments of the apical dendrite are seen, while spine count in the distal dendrite remains normal. These results indicate that pruning is involved in behavioral extinction, while maintenance of spines is a probable mechanism that mediates the protecting effect against amnesic treatments produced by enhanced training. PMID:22438840

  1. Chronic CB1 cannabinoid receptor antagonism persistently increases dendritic spine densities in brain regions important to zebra finch vocal learning and production in an antidepressant-sensitive manner.

    PubMed

    Holland, Tessa L; Soderstrom, Ken

    2017-10-01

    During typical late-postnatal CNS development, net reductions in dendritic spine densities are associated with activity-dependent learning. Prior results showed agonist exposure in young animals increased spine densities in a subset of song regions while adult exposures did not, suggesting endocannabinoid signaling regulates dendritic spine dynamics important to vocal development. Here we addressed this question using the CB1 receptor-selective antagonist SR141716A (SR) to disrupt endocannabinoid signaling both during and after vocal learning. We hypothesized antagonist exposure during vocal development, but not adulthood, would alter spine densities. Following 25days of exposure and a 25day maturation period, 3D reconstructions of Golgi-Cox stained neurons were used to measure spine densities. We found antagonist treatments during both age periods increased densities within Area X (basal ganglia) and following adult treatments within HVC (premotor cortical-like). Results suggest both inappropriate cannabinoid receptor stimulation and inhibition are capable of similar disregulatory effects during establishment of circuits important to vocal learning, with antagonism extending these effects through adulthood. Given clinical evidence of depressant effects of SR, we tested the ability of the antidepressant monoamine oxidase inhibitor (MAOI) phenelzine to mitigate SR-induced spine density increases. This was confirmed implicating interaction between monoamine and endocannabinoid systems. Finally, we evaluated acute effects of these drugs to alter ability of novel song exposure to increase spine densities in auditory NCM and other regions, finding when combined, SR and phenelzine increased densities within Area X. These results contribute to understanding relevance of dendritic spine dynamics in neuronal development, drug abuse, and depression. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Sleep contributes to dendritic spine formation and elimination in the developing mouse somatosensory cortex.

    PubMed

    Yang, Guang; Gan, Wen-Biao

    2012-11-01

    Sleep is maximal during early postnatal life when rapid and extensive synapse remodeling occurs. It remains unknown whether and how sleep affects synapse development and plasticity. Using transcranial two-photon microscopy, we examined the formation and elimination of fluorescently labeled dendritic spines and filopodia of Layer 5 pyramidal neurons in the barrel cortex of 3-week-old mice during wakefulness and sleep. We observed high turnover of dendritic protrusions over 2 h in both wake and sleep states. The formation rate of dendritic spines or filopodia over 2 h was comparable between the two states. The elimination rate of dendritic spines or filopodia was lower during 2-h wakefulness than during 2-h sleep. Similar results were observed on dendritic protrusion dynamics over 12-h light/dark cycle when mice spent more time asleep or awake. The substantial remodeling of dendritic protrusions during the sleep state supports the notion that sleep plays an important role in the development and plasticity of synaptic connections in the mouse cortex.

  3. Stressful experience has opposite effects on dendritic spines in the hippocampus of cycling versus masculinized females

    PubMed Central

    Dalla, Christina; Whetstone, Abigail S.; Hodes, Georgia E.; Shors, Tracey J.

    2012-01-01

    Stress increases associative learning and the density of dendritic spines in the hippocampus of male rats. In contrast, exposure to the same stressor impairs associative learning and reduces spine density in females. These effects in females are most evident when they are in the proestrus phase of the estrous cycle. An injection of testosterone at the time of birth masculinizes the female brain. In adulthood, masculinized females respond like males do to stress, i.e. they learn better. Here, we hypothesized that stress would increase spine densities on pyramidal neurons in area CA1 of the hippocampus of masculinized females, because stress enhances learning ability in both males and masculinized females. To test this, we used Golgi impregnation to stain tissue from masculinized and cycling females that were exposed to the acute stressor and sacrificed one day later. There was a significant interaction between stressor exposure and testosterone treatment at birth (p<0.001). In general, cycling females that were stressed tended to possess fewer spines on apical and basal dendrites in the CA1 area of the hippocampus, whereas the masculinized females possessed significantly more spines after the stressor. These findings underscore the plastic nature of dendritic spines. They suggest that their response to stress in adulthood is organized by the presence of testosterone during very early development. Such a process may represent a mechanism for altering learning abilities after an acute traumatic experience. PMID:18952150

  4. Changes in dendritic spine density in the nucleus accumbens do not underlie ethanol sensitization.

    PubMed

    Nona, Christina N; Bermejo, Marie Kristel; Ramsey, Amy J; Nobrega, José N

    2015-12-01

    Behavioral sensitization to various drugs of abuse has been shown to change dendritic spine density and/or morphology of nucleus accumbens (NAc) medium spiny neurons, an effect seen across drug classes. However, is it not known whether behavioral sensitization to ethanol (EtOH) is also associated with structural changes in this region. Here we compared dendritic spine density and morphology between mice showing High vs. Low levels of EtOH sensitization and found that high levels of EtOH sensitization were not associated with changes in dendritic spine density or spine type. Unexpectedly, however, a significant increase in the density of stubby-type spines was seen in mice that were resistant to sensitization. Since the presence of this spine type has been associated with long-term depression and cognitive/learning deficits this may explain why these mice fail to sensitize and why they show poor performance in conditioning tasks, as previously shown. A possible causal role for structural plasticity in behavioral sensitization to various drugs has been debated. In the case of EtOH sensitization, our results suggest that drug-induced changes in structural plasticity in the accumbens neurons may not be the cause of sensitized behavior. © 2015 Wiley Periodicals, Inc.

  5. Cell-Autonomous Regulation of Dendritic Spine Density by PirB

    PubMed Central

    2016-01-01

    Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirBfl/fl), PirB was deleted only from L2/3 cortical pyramidal neurons in vivo by timed in utero electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre– neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life. PMID:27752542

  6. Cell-Autonomous Regulation of Dendritic Spine Density by PirB.

    PubMed

    Vidal, George S; Djurisic, Maja; Brown, Kiana; Sapp, Richard W; Shatz, Carla J

    2016-01-01

    Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirB(fl/fl)), PirB was deleted only from L2/3 cortical pyramidal neurons in vivo by timed in utero electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre(-) neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life.

  7. Autocrine BDNF-TrkB signalling within a single dendritic spine.

    PubMed

    Harward, Stephen C; Hedrick, Nathan G; Hall, Charles E; Parra-Bueno, Paula; Milner, Teresa A; Pan, Enhui; Laviv, Tal; Hempstead, Barbara L; Yasuda, Ryohei; McNamara, James O

    2016-10-06

    Brain-derived neurotrophic factor (BDNF) and its receptor TrkB are crucial for many forms of neuronal plasticity, including structural long-term potentiation (sLTP), which is a correlate of an animal's learning. However, it is unknown whether BDNF release and TrkB activation occur during sLTP, and if so, when and where. Here, using a fluorescence resonance energy transfer-based sensor for TrkB and two-photon fluorescence lifetime imaging microscopy, we monitor TrkB activity in single dendritic spines of CA1 pyramidal neurons in cultured murine hippocampal slices. In response to sLTP induction, we find fast (onset < 1 min) and sustained (>20 min) activation of TrkB in the stimulated spine that depends on NMDAR (N-methyl-d-aspartate receptor) and CaMKII signalling and on postsynaptically synthesized BDNF. We confirm the presence of postsynaptic BDNF using electron microscopy to localize endogenous BDNF to dendrites and spines of hippocampal CA1 pyramidal neurons. Consistent with these findings, we also show rapid, glutamate-uncaging-evoked, time-locked BDNF release from single dendritic spines using BDNF fused to superecliptic pHluorin. We demonstrate that this postsynaptic BDNF-TrkB signalling pathway is necessary for both structural and functional LTP. Together, these findings reveal a spine-autonomous, autocrine signalling mechanism involving NMDAR-CaMKII-dependent BDNF release from stimulated dendritic spines and subsequent TrkB activation on these same spines that is crucial for structural and functional plasticity.

  8. Activity-dependent accumulation of calcium in Purkinje cell dendritic spines

    SciTech Connect

    Andrews, S.B.; Leapman, R.D.; Landis, D.M.; Reese, T.S.

    1988-03-01

    The calcium content of synapses of parallel fibers on Purkinje cell dendritic spines was determined by electron probe x-ray microanalysis of freeze-dried cryosections from directly frozen slices of mouse cerebellar cortex. In fresh slices frozen within 20-30 sec of excision, calcium concentrations ranging from 0.8 to 18.6 mmol/kg of dry weight were measured in cisterns of smooth endoplasmic reticulum within Purkinje cell dendritic spines. The average calcium content of spine cisterns in rapidly excised slices (6.7 +/- 0.6 mmol/kg of dry weight +/- SEM) was higher than the average calcium content of spine cisterns in brain slices incubated without stimulation for 1-2 hr before direct freezing (2.5 +/- 0.4 mmol/kg of dry weight). Depolarization of incubated cerebellar slices by isotonic 55 mM KCl resulted in the accumulation within spine cisterns of very high amounts of calcium or isotonically substituted strontium, both derived from the extracellular fluid. These results suggest that one function of spine cisterns is to sequester free calcium that enters the spine through ligand-gated or voltage-gated channels during synaptic transmission.

  9. Targeted intracellular voltage recordings from dendritic spines using quantum-dot-coated nanopipettes

    NASA Astrophysics Data System (ADS)

    Jayant, Krishna; Hirtz, Jan J.; Plante, Ilan Jen-La; Tsai, David M.; de Boer, Wieteke D. A. M.; Semonche, Alexa; Peterka, Darcy S.; Owen, Jonathan S.; Sahin, Ozgur; Shepard, Kenneth L.; Yuste, Rafael

    2017-05-01

    Dendritic spines are the primary site of excitatory synaptic input onto neurons, and are biochemically isolated from the parent dendritic shaft by their thin neck. However, due to the lack of direct electrical recordings from spines, the influence that the neck resistance has on synaptic transmission, and the extent to which spines compartmentalize voltage, specifically excitatory postsynaptic potentials, albeit critical, remains controversial. Here, we use quantum-dot-coated nanopipette electrodes (tip diameters ∼15-30 nm) to establish the first intracellular recordings from targeted spine heads under two-photon visualization. Using simultaneous somato-spine electrical recordings, we find that back propagating action potentials fully invade spines, that excitatory postsynaptic potentials are large in the spine head (mean 26 mV) but are strongly attenuated at the soma (0.5-1 mV) and that the estimated neck resistance (mean 420 MΩ) is large enough to generate significant voltage compartmentalization. Nanopipettes can thus be used to electrically probe biological nanostructures.

  10. Perinatal undernutrition attenuates field excitatory postsynaptic potentials and influences dendritic spine density and morphology in hippocampus of male rat offspring.

    PubMed

    Zhang, Y; Wei, J; Yang, Z

    2013-08-06

    Perinatal undernutrition affects the hippocampus, a brain region crucial for learning and memory. However, far less is known about the changes of dendritic spine density and morphology related to hippocampal synaptic plasticity. As dendritic spines are dynamic structures essential for synaptic plasticity and serve as the primary post-synaptic location of the excitatory neurotransmission that underlies learning and memory, the aim of the present study was to investigate whether the perinatal undernutrition affected hippocampal synaptic plasticity accompanied by the change of dendritic spines in anesthetized rats. An input-output curve was first determined using the measurements of field excitatory postsynaptic potential (fEPSP) slope in response to a series of stimulation intensities. Long-term potentiation (LTP) induced by high-frequency stimulation was recorded in the Schaffer collateral-CA1 pathway. Post-tetanic potentiation derived from the fEPSP slope was also measured immediately after LTP induction. Quantitative data of dendritic spines from hippocampal CA1 pyramidal cells were obtained using Golgi staining. The results showed that 50% perinatal food restriction (FR50) impaired the magnitude of LTP of the fEPSP slope in the Schaffer collateral-CA1 pathway. Additionally, FR50 reduced overall spine densities in both basal dendrites and apical dendrites of hippocampal CA1 pyramidal cells. Moreover, FR50 reduced type densities of thin and mushroom spines in apical dendrites, whereas a reduction in the type of mushroom spines was only observed in the basal dendrites of hippocampal CA1 pyramidal cells. These findings suggested that perinatal undernutrition decreased excitatory synaptic input and further affected the processing of information in a given network by selectively reducing the number of special dendritic spines. Thus, these changes in the density and the types of dendritic spines in CA1 pyramidal neurons may partly explain the impaired hippocampal

  11. Seeding and transgenic overexpression of alpha-synuclein triggers dendritic spine pathology in the neocortex.

    PubMed

    Blumenstock, Sonja; Rodrigues, Eva F; Peters, Finn; Blazquez-Llorca, Lidia; Schmidt, Felix; Giese, Armin; Herms, Jochen

    2017-05-01

    Although misfolded and aggregated α-synuclein (α-syn) is recognized in the disease progression of synucleinopathies, its role in the impairment of cortical circuitries and synaptic plasticity remains incompletely understood. We investigated how α-synuclein accumulation affects synaptic plasticity in the mouse somatosensory cortex using two distinct approaches. Long-term in vivo imaging of apical dendrites was performed in mice overexpressing wild-type human α-synuclein. Additionally, intracranial injection of preformed α-synuclein fibrils was performed to induce cortical α-syn pathology. We find that α-synuclein overexpressing mice show decreased spine density and abnormalities in spine dynamics in an age-dependent manner. We also provide evidence for the detrimental effects of seeded α-synuclein aggregates on dendritic architecture. We observed spine loss as well as dystrophic deformation of dendritic shafts in layer V pyramidal neurons. Our results provide a link to the pathophysiology underlying dementia associated with synucleinopathies and may enable the evaluation of potential drug candidates on dendritic spine pathology in vivo. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  12. Evidence of calcium-permeable AMPA receptors in dendritic spines of CA1 pyramidal neurons

    PubMed Central

    Mattison, Hayley A.; Bagal, Ashish A.; Mohammadi, Michael; Pulimood, Nisha S.; Reich, Christian G.; Alger, Bradley E.; Kao, Joseph P. Y.

    2014-01-01

    GluA2-lacking, calcium-permeable α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors (AMPARs) have unique properties, but their presence at excitatory synapses in pyramidal cells is controversial. We have tested certain predictions of the model that such receptors are present in CA1 cells and show here that the polyamine spermine, but not philanthotoxin, causes use-dependent inhibition of synaptically evoked excitatory responses in stratum radiatum, but not s. oriens, in cultured and acute hippocampal slices. Stimulation of single dendritic spines by photolytic release of caged glutamate induced an N-methyl-d-aspartate receptor-independent, use- and spermine-sensitive calcium influx only at apical spines in cultured slices. Bath application of glutamate also triggered a spermine-sensitive influx of cobalt into CA1 cell dendrites in s. radiatum. Responses of single apical, but not basal, spines to photostimulation displayed prominent paired-pulse facilitation (PPF) consistent with use-dependent relief of cytoplasmic polyamine block. Responses at apical dendrites were diminished, and PPF was increased, by spermine. Intracellular application of pep2m, which inhibits recycling of GluA2-containing AMPARs, reduced apical spine responses and increased PPF. We conclude that some calcium-permeable, polyamine-sensitive AMPARs, perhaps lacking GluA2 subunits, are present at synapses on apical dendrites of CA1 pyramidal cells, which may allow distinct forms of synaptic plasticity and computation at different sets of excitatory inputs. PMID:24760782

  13. Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia-normothermia in vivo: A three-dimensional electron microscope study.

    PubMed

    Popov, V I; Medvedev, N I; Patrushev, I V; Ignat'ev, D A; Morenkov, E D; Stewart, M G

    2007-11-09

    A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2-4 degrees C), or after warming and recovery to the normothermic state (34 degrees C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 degrees C at which time core rectal temperature was 15 degrees C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal.

  14. Conditional self-discrimination enhances dendritic spine number and dendritic length at prefrontal cortex and hippocampal neurons of rats.

    PubMed

    Penagos-Corzo, Julio C; Bonilla, Andrea; Rodríguez-Moreno, Antonio; Flores, Gonzalo; Negrete-Díaz, José V

    2015-11-01

    We studied conditional self-discrimination (CSD) in rats and compared the neuronal cytoarchitecture of untrained animals and rats that were trained in self-discrimination. For this purpose, we used thirty 10-week-old male rats were randomized into three groups: one control group and two conditioning groups: a comparison group (associative learning) and an experimental group (self-discrimination). At the end of the conditioning process, the experimental group managed to discriminate their own state of thirst. After the conditioning process, dendritic morphological changes in the pyramidal neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus were evaluated using Golgi-Cox stain method and then analyzed by the Sholl method. Differences were found in total dendritic length and spine density. Animals trained in self-discrimination showed an increase in the dendritic length and the number of dendritic spines of neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus. Our data suggest that conditional self-discrimination improves the connectivity of the prefrontal cortex and dorsal CA1, which has implications for memory and learning processes.

  15. 3D-modeling of the spine using EOS imaging system: Inter-reader reproducibility and reliability.

    PubMed

    Rehm, Johannes; Germann, Thomas; Akbar, Michael; Pepke, Wojciech; Kauczor, Hans-Ulrich; Weber, Marc-André; Spira, Daniel

    2017-01-01

    To retrospectively assess the interreader reproducibility and reliability of EOS 3D full spine reconstructions in patients with adolescent idiopathic scoliosis (AIS). 73 patients with mean age of 17 years and a moderate AIS (median Cobb Angle 18.2°) obtained low-dose standing biplanar radiographs with EOS. Two independent readers performed "full spine" 3D reconstructions of the spine with the "full-spine" method adjusting the bone contour of every thoracic and lumbar vertebra (Th1-L5). Interreader reproducibility was assessed regarding rotation of every single vertebra in the coronal (i.e. frontal), sagittal (i.e. lateral), and axial plane, T1/T12 kyphosis, T4/T12 kyphosis, L1/L5 lordosis, L1/S1 lordosis and pelvic parameters. Radiation exposure, scan-time and 3D reconstruction time were recorded. Interclass correlation (ICC) ranged between 0.83 and 0.98 for frontal vertebral rotation, between 0.94 and 0.99 for lateral vertebral rotation and between 0.51 and 0.88 for axial vertebral rotation. ICC was 0.92 for T1/T12 kyphosis, 0.95 for T4/T12 kyphosis, 0.90 for L1/L5 lordosis, 0.85 for L1/S1 lordosis, 0.97 for pelvic incidence, 0.96 for sacral slope, 0.98 for sagittal pelvic tilt and 0.94 for lateral pelvic tilt. The mean time for reconstruction was 14.9 minutes (reader 1: 14.6 minutes, reader 2: 15.2 minutes, p<0.0001). The mean total absorbed dose was 593.4μGy ±212.3 per patient. EOS "full spine" 3D angle measurement of vertebral rotation proved to be reliable and was performed in an acceptable reconstruction time. Interreader reproducibility of axial rotation was limited to some degree in the upper and middle thoracic spine due the obtuse angulation of the pedicles and the processi spinosi in the frontal view somewhat complicating their delineation.

  16. Stress and trauma: BDNF control of dendritic-spine formation and regression.

    PubMed

    Bennett, M R; Lagopoulos, J

    2014-01-01

    Chronic restraint stress leads to increases in brain derived neurotrophic factor (BDNF) mRNA and protein in some regions of the brain, e.g. the basal lateral amygdala (BLA) but decreases in other regions such as the CA3 region of the hippocampus and dendritic spine density increases or decreases in line with these changes in BDNF. Given the powerful influence that BDNF has on dendritic spine growth, these observations suggest that the fundamental reason for the direction and extent of changes in dendritic spine density in a particular region of the brain under stress is due to the changes in BDNF there. The most likely cause of these changes is provided by the stress initiated release of steroids, which readily enter neurons and alter gene expression, for example that of BDNF. Of particular interest is how glucocorticoids and mineralocorticoids tend to have opposite effects on BDNF gene expression offering the possibility that differences in the distribution of their receptors and of their downstream effects might provide a basis for the differential transcription of the BDNF genes. Alternatively, differences in the extent of methylation and acetylation in the epigenetic control of BDNF transcription are possible in different parts of the brain following stress. Although present evidence points to changes in BDNF transcription being the major causal agent for the changes in spine density in different parts of the brain following stress, steroids have significant effects on downstream pathways from the TrkB receptor once it is acted upon by BDNF, including those that modulate the density of dendritic spines. Finally, although glucocorticoids play a canonical role in determining BDNF modulation of dendritic spines, recent studies have shown a role for corticotrophin releasing factor (CRF) in this regard. There is considerable improvement in the extent of changes in spine size and density in rodents with forebrain specific knockout of CRF receptor 1 (CRFR1) even when

  17. Reversible loss of dendritic spines and altered excitability after chronic epilepsy in hippocampal slice cultures.

    PubMed Central

    Müller, M; Gähwiler, B H; Rietschin, L; Thompson, S M

    1993-01-01

    The morphological and functional consequences of epileptic activity were investigated by applying the convulsants bicuculline and/or picrotoxin to mature rat hippocampal slice cultures. After 3 days, some cells in all hippocampal subfields showed signs of degeneration, including swollen somata, vacuolation, and dendritic deformities, whereas others displayed only a massive reduction in the number of their dendritic spines. Intracellular recordings from CA3 pyramidal cells revealed a decrease in the amplitude of evoked excitatory synaptic potentials. gamma-Aminobutyric acid-releasing interneurons and inhibitory synaptic potentials were unaffected. Seven days after withdrawal of convulsants, remaining cells possessed a normal number of dendritic spines, thus demonstrating a considerable capacity for recovery. The pathological changes induced by convulsants are similar to those found in the hippocampi of human epileptics, suggesting that they are a consequence, rather than a cause, of epilepsy. Images PMID:8093558

  18. Imaging ERK and PKA Activation in Single Dendritic Spines during Structural Plasticity.

    PubMed

    Tang, Shen; Yasuda, Ryohei

    2017-03-22

    Extracellular signal-regulated kinase (ERK) and protein kinase A (PKA) play important roles in LTP and spine structural plasticity. While fluorescence resonance energy transfer (FRET)-based sensors for these kinases had previously been developed, they did not provide sufficient sensitivity for imaging small neuronal compartments, such as single dendritic spines in brain slices. Here we improved the sensitivity of FRET-based kinase sensors for monitoring kinase activity under two-photon fluorescence lifetime imaging microscopy (2pFLIM). Using these improved sensors, we succeeded in imaging ERK and PKA activation in single dendritic spines during structural long-term potentiation (sLTP) in hippocampal CA1 pyramidal neurons, revealing that the activation of these kinases spreads widely with length constants of more than 10 μm. The strategy for improvement of sensors used here should be applicable for developing highly sensitive biosensors for various protein kinases. VIDEO ABSTRACT.

  19. Increased levels of acidic calponin during dendritic spine plasticity after pilocarpine-induced seizures.

    PubMed

    Ferhat, Lotfi; Esclapez, Monique; Represa, Alfonso; Fattoum, Abdellatif; Shirao, Tomoaki; Ben-Ari, Yezekiel

    2003-01-01

    We have previously shown that, in HEK 293 cells, overexpression of acidic calponin, an actin-binding protein, induces remodeling of actin filaments, leading to a change in cell morphology. In addition, this protein is found in dendritic spines of adult hippocampal neurons. We hypothesized that this protein plays a role in regulating actin-based filaments during dendritic spine plasticity. To assess this hypothesis, the pilocarpine model of temporal lobe epilepsy was selected because an important reorganization of the glutamatergic network, which includes an aberrant sprouting of granule cell axons, neo-synaptogenesis, and dendritic spine remodeling, is well established in the dentate gyrus. This reorganization begins after the initial period of status epilepticus after pilocarpine injection, during the silent period when animals display a normal behavior, and reaches a plateau at the chronic stage when the animals have developed spontaneous recurrent seizures. Our data show that the intensity of immunolabeling for acidic calponin was clearly increased in the inner one-third of the molecular layer of the dentate gyrus, the site of mossy fiber sprouting, and neo-synaptogenesis, at 1 and 2 weeks after pilocarpine injection (silent period) when the reorganization was taking place. In contrast, in chronic pilocarpine-treated animals, when the reorganization was established, the levels of labeling for acidic calponin in the inner molecular layer were similar to those observed in control rats. In addition, double immunostaining studies suggested that the increase in acidic calponin levels occurred within the dendritic spines. Altogether, these results are consistent with an involvement of acidic calponin in dendritic spine plasticity.

  20. Protein kinase D promotes plasticity-induced F-actin stabilization in dendritic spines and regulates memory formation

    PubMed Central

    Bencsik, Norbert; Szíber, Zsófia; Liliom, Hanna; Tárnok, Krisztián; Borbély, Sándor; Gulyás, Márton; Rátkai, Anikó; Szűcs, Attila; Hazai-Novák, Diána; Ellwanger, Kornelia; Rácz, Bence; Pfizenmaier, Klaus; Hausser, Angelika

    2015-01-01

    Actin turnover in dendritic spines influences spine development, morphology, and plasticity, with functional consequences on learning and memory formation. In nonneuronal cells, protein kinase D (PKD) has an important role in stabilizing F-actin via multiple molecular pathways. Using in vitro models of neuronal plasticity, such as glycine-induced chemical long-term potentiation (LTP), known to evoke synaptic plasticity, or long-term depolarization block by KCl, leading to homeostatic morphological changes, we show that actin stabilization needed for the enlargement of dendritic spines is dependent on PKD activity. Consequently, impaired PKD functions attenuate activity-dependent changes in hippocampal dendritic spines, including LTP formation, cause morphological alterations in vivo, and have deleterious consequences on spatial memory formation. We thus provide compelling evidence that PKD controls synaptic plasticity and learning by regulating actin stability in dendritic spines. PMID:26304723

  1. Urokinase-Type Plasminogen Activator Promotes Dendritic Spine Recovery and Improves Neurological Outcome Following Ischemic Stroke

    PubMed Central

    Wu, Fang; Catano, Marcela; Echeverry, Ramiro; Torre, Enrique; Haile, Woldeab B.; An, Jie; Chen, Changhua; Cheng, Lihong; Nicholson, Andrew; Tong, Frank C.; Park, Jaekeun

    2014-01-01

    Spines are dendritic protrusions that receive most of the excitatory input in the brain. Early after the onset of cerebral ischemia dendritic spines in the peri-infarct cortex are replaced by areas of focal swelling, and their re-emergence from these varicosities is associated with neurological recovery after acute ischemic stroke (AIS). Urokinase-type plasminogen activator (uPA) is a serine proteinase that plays a central role in tissue remodeling via binding to the urokinase plasminogen activator receptor (uPAR). We report that cerebral cortical neurons release uPA during the recovery phase from ischemic stroke in vivo or hypoxia in vitro. Although uPA does not have an effect on ischemia- or hypoxia-induced neuronal death, genetic deficiency of uPA (uPA−/−) or uPAR (uPAR−/−) abrogates functional recovery after AIS. Treatment with recombinant uPA after ischemic stroke induces neurological recovery in wild-type and uPA−/− but not in uPAR−/− mice. Diffusion tensor imaging studies indicate that uPA−/− mice have increased water diffusivity and decreased anisotropy associated with impaired dendritic spine recovery and decreased length of distal neurites in the peri-infarct cortex. We found that the excitotoxic injury induces the clustering of uPAR in dendritic varicosities, and that the binding of uPA to uPAR promotes the reorganization of the actin cytoskeleton and re-emergence of dendritic filopodia from uPAR-enriched varicosities. This effect is independent of uPA's proteolytic properties and instead is mediated by Rac-regulated profilin expression and cofilin phosphorylation. Our data indicate that binding of uPA to uPAR promotes dendritic spine recovery and improves functional outcome following AIS. PMID:25339736

  2. One-step synthesis of 3D dendritic gold/polypyrrole nanocomposites via a self-assembly method

    NASA Astrophysics Data System (ADS)

    Huang, Kun; Zhang, Yuanjian; Han, Dongxue; Shen, Yanfei; Wang, Zhijuan; Yuan, Junhua; Zhang, Qixian; Niu, Li

    2006-01-01

    Novel spherical three-dimensional (3D) dendritic gold-polypyrrole nanocomposites were successfully prepared in the presence of an amphiphilic p-toluene sulfonic acid (TSA) as dopant and surfactant via a self-assembly process which is based on the oxidation of pyrrole (Py) and the reduction of the chloroaurate ions, yielding PPy and Au(0) simultaneously. It was found that the probability of obtaining dendritic Au@PPy/TSA nanostructures depended on the concentration of TSA and the rate of addition of the oxidant (HAuCl4). It was also proposed that the supramolecular micelles formed by Py and TSA play the role of a 'soft template' to produce the dendritic Au@PPy/TSA nanocomposites.

  3. Abnormal intrinsic dynamics of dendritic spines in a fragile X syndrome mouse model in vivo

    PubMed Central

    Nagaoka, Akira; Takehara, Hiroaki; Hayashi-Takagi, Akiko; Noguchi, Jun; Ishii, Kazuhiko; Shirai, Fukutoshi; Yagishita, Sho; Akagi, Takanori; Ichiki, Takanori; Kasai, Haruo

    2016-01-01

    Dendritic spine generation and elimination play an important role in learning and memory, the dynamics of which have been examined within the neocortex in vivo. Spine turnover has also been detected in the absence of specific learning tasks, and is frequently exaggerated in animal models of autistic spectrum disorder (ASD). The present study aimed to examine whether the baseline rate of spine turnover was activity-dependent. This was achieved using a microfluidic brain interface and open-dura surgery, with the goal of abolishing neuronal Ca2+ signaling in the visual cortex of wild-type mice and rodent models of fragile X syndrome (Fmr1 knockout [KO]). In wild-type and Fmr1 KO mice, the majority of baseline turnover was found to be activity-independent. Accordingly, the application of matrix metalloproteinase-9 inhibitors selectively restored the abnormal spine dynamics observed in Fmr1 KO mice, without affecting the intrinsic dynamics of spine turnover in wild-type mice. Such findings indicate that the baseline turnover of dendritic spines is mediated by activity-independent intrinsic dynamics. Furthermore, these results suggest that the targeting of abnormal intrinsic dynamics might pose a novel therapy for ASD. PMID:27221801

  4. Ca2+ sensor proteins in dendritic spines: a race for Ca2+

    PubMed Central

    Raghuram, Vijeta; Sharma, Yogendra; Kreutz, Michael R.

    2012-01-01

    Dendritic spines are believed to be micro-compartments of Ca2+ regulation. In a recent study, it was suggested that the ubiquitous and evolutionarily conserved Ca2+ sensor, calmodulin (CaM), is the first to intercept Ca2+ entering the spine and might be responsible for the fast decay of Ca2+ transients in spines. Neuronal calcium sensor (NCS) and neuronal calcium-binding protein (nCaBP) families consist of Ca2+ sensors with largely unknown synaptic functions despite an increasing number of interaction partners. Particularly how these sensors operate in spines in the presence of CaM has not been discussed in detail before. The limited Ca2+ resources and the existence of common targets create a highly competitive environment where Ca2+ sensors compete with each other for Ca2+ and target binding. In this review, we take a simple numerical approach to put forth possible scenarios and their impact on signaling via Ca2+ sensors of the NCS and nCaBP families. We also discuss the ways in which spine geometry and properties of ion channels, their kinetics and distribution, alter the spatio-temporal aspects of Ca2+ transients in dendritic spines, whose interplay with Ca2+ sensors in turn influences the race for Ca2+. PMID:22586368

  5. Ceramide Levels Regulated by Carnitine Palmitoyltransferase 1C Control Dendritic Spine Maturation and Cognition*

    PubMed Central

    Carrasco, Patricia; Sahún, Ignasi; McDonald, Jerome; Ramírez, Sara; Jacas, Jordi; Gratacós, Esther; Sierra, Adriana Y.; Serra, Dolors; Herrero, Laura; Acker-Palmer, Amparo; Hegardt, Fausto G.; Dierssen, Mara; Casals, Núria

    2012-01-01

    The brain-specific isoform carnitine palmitoyltransferase 1C (CPT1C) has been implicated in the hypothalamic regulation of food intake and energy homeostasis. Nevertheless, its molecular function is not completely understood, and its role in other brain areas is unknown. We demonstrate that CPT1C is expressed in pyramidal neurons of the hippocampus and is located in the endoplasmic reticulum throughout the neuron, even inside dendritic spines. We used molecular, cellular, and behavioral approaches to determine CPT1C function. First, we analyzed the implication of CPT1C in ceramide metabolism. CPT1C overexpression in primary hippocampal cultured neurons increased ceramide levels, whereas in CPT1C-deficient neurons, ceramide levels were diminished. Correspondingly, CPT1C knock-out (KO) mice showed reduced ceramide levels in the hippocampus. At the cellular level, CPT1C deficiency altered dendritic spine morphology by increasing immature filopodia and reducing mature mushroom and stubby spines. Total protrusion density and spine head area in mature spines were unaffected. Treatment of cultured neurons with exogenous ceramide reverted the KO phenotype, as did ectopic overexpression of CPT1C, indicating that CPT1C regulation of spine maturation is mediated by ceramide. To study the repercussions of the KO phenotype on cognition, we performed the hippocampus-dependent Morris water maze test on mice. Results show that CPT1C deficiency strongly impairs spatial learning. All of these results demonstrate that CPT1C regulates the levels of ceramide in the endoplasmic reticulum of hippocampal neurons, and this is a relevant mechanism for the correct maturation of dendritic spines and for proper spatial learning. PMID:22539351

  6. Chronic alcohol drinking alters neuronal dendritic spines in the brain reward center nucleus accumbens.

    PubMed

    Zhou, Feng C; Anthony, Bruce; Dunn, Kenneth W; Lindquist, W Brent; Xu, Zao C; Deng, Ping

    2007-02-23

    Alcohol is known to affect glutamate transmission. However, how chronic alcohol affects the synaptic structure mediating glutamate transmission is unknown. Repeated alcohol exposure in a subject with familial alcoholic history often leads to alcohol addiction. The current study adopts alcohol-preferring rats, which are known to develop high drinking. Two-photon microscopy analysis indicates that chronic alcohol of 14 weeks either, under continuous alcohol (C-Alc) or with repeated deprivation (RD-Alc), causes dysmorphology--thickened, beaded, and disoriented dendrites that are reminiscent of reactive astrocytes--in a subpopulation of medium spiny neurons. The density of dendritic spines was found differentially lower in the nucleus accumbens of RD-Alc and C-Alc groups as compared with those of Water groups. Large-sized spines and multiple-headed spines were increased in the RD-Alc group. The NMDA receptor subunit NR1 proteins, as analyzed with Western blot, were upregulated in C-Alc, but not in RD-Alc. The upregulated NMDA receptor subunits of NR1 however, are predominantly a splice variant isoform with truncated exon 21, which is required for membrane-bound trafficking or anchoring into a spine synaptic site. These maladaptations may contribute to the transformation of spines. The changes, in density and head-size of spines and the corresponding NMDA receptors, demonstrated an alteration of microcircuitry for glutamate reception. The current study demonstrates for the first time that chronic alcohol exposure causes structural alteration of dendrites and their spines in the key reward brain region in animals that have a genetic background leading to alcohol addiction.

  7. Arg kinase regulates prefrontal dendritic spine refinement and cocaine-induced plasticity.

    PubMed

    Gourley, Shannon L; Olevska, Anastasia; Warren, M Sloan; Taylor, Jane R; Koleske, Anthony J

    2012-02-15

    Adolescence is characterized by vulnerability to the development of neuropsychiatric disorders including drug addiction, as well as prefrontal cortical refinement that culminates in structural stability in adulthood. Neuronal refinement and stabilization are hypothesized to confer resilience to poor decision making and addictive-like behaviors, although intracellular mechanisms are largely unknown. We characterized layer V prefrontal dendritic spine development and refinement in adolescent wild-type mice and mice lacking the cytoskeletal regulatory protein Abl-related gene (Arg) kinase. Relative to hippocampal CA1 pyramidal neurons, which exhibited a nearly linear increase in spine density up to postnatal day 60 (P60), wild-type prefrontal spine density peaked at P31, and then declined by 18% by P56-P60. In contrast, dendritic spines in mice lacking Arg destabilized by P31, leading to a net loss in both structures. Destabilization corresponded temporally to the emergence of exaggerated psychomotor sensitivity to cocaine. Moreover, cocaine reduced dendritic spine density in wild-type orbitofrontal cortex and enlarged remaining spine heads, but arg(-/-) spines were unresponsive. Local application of Arg or actin polymerization inhibitors exaggerated cocaine sensitization, as did reduced gene dosage of the Arg substrate, p190RhoGAP. Genetic and pharmacological Arg inhibition also retarded instrumental reversal learning and potentiated responding for reward-related cues, providing evidence that Arg regulates both psychomotor sensitization and decision-making processes implicated in addiction. These findings also indicate that structural refinement in the adolescent orbitofrontal cortex mitigates psychostimulant sensitivity and support the emerging perspective that the structural response to cocaine may, at any age, have behaviorally protective consequences.

  8. EphA Signaling Promotes Actin-based Dendritic Spine Remodeling through Slingshot Phosphatase*

    PubMed Central

    Zhou, Lei; Jones, Emma V.; Murai, Keith K.

    2012-01-01

    Actin cytoskeletal remodeling plays a critical role in transforming the morphology of subcellular structures across various cell types. In the brain, restructuring of dendritic spines through actin cytoskeleletal reorganization is implicated in the regulation of synaptic efficacy and the storage of information in neural circuits. However, the upstream pathways that provoke actin-based spine changes remain only partly understood. Here we show that EphA receptor signaling remodels spines by triggering a sequence of events involving actin filament rearrangement and synapse/spine reorganization. Rapid EphA signaling over minutes activates the actin filament depolymerizing/severing factor cofilin, alters F-actin distribution in spines, and causes transient spine elongation through the phosphatases slingshot 1 (SSH1) and calcineurin/protein phosphatase 2B (PP2B). This early phase of spine extension is followed by synaptic reorganization events that take place over minutes to hours and involve the relocation of pre/postsynaptic components and ultimately spine retraction. Thus, EphA receptors utilize discrete cellular and molecular pathways to promote actin-based structural plasticity of excitatory synapses. PMID:22282498

  9. Parametric modeling of the intervertebral disc space in 3D: application to CT images of the lumbar spine.

    PubMed

    Korez, Robert; Likar, Boštjan; Pernuš, Franjo; Vrtovec, Tomaž

    2014-10-01

    Gradual degeneration of intervertebral discs of the lumbar spine is one of the most common causes of low back pain. Although conservative treatment for low back pain may provide relief to most individuals, surgical intervention may be required for individuals with significant continuing symptoms, which is usually performed by replacing the degenerated intervertebral disc with an artificial implant. For designing implants with good bone contact and continuous force distribution, the morphology of the intervertebral disc space and vertebral body endplates is of considerable importance. In this study, we propose a method for parametric modeling of the intervertebral disc space in three dimensions (3D) and show its application to computed tomography (CT) images of the lumbar spine. The initial 3D model of the intervertebral disc space is generated according to the superquadric approach and therefore represented by a truncated elliptical cone, which is initialized by parameters obtained from 3D models of adjacent vertebral bodies. In an optimization procedure, the 3D model of the intervertebral disc space is incrementally deformed by adding parameters that provide a more detailed morphometric description of the observed shape, and aligned to the observed intervertebral disc space in the 3D image. By applying the proposed method to CT images of 20 lumbar spines, the shape and pose of each of the 100 intervertebral disc spaces were represented by a 3D parametric model. The resulting mean (±standard deviation) accuracy of modeling was 1.06±0.98mm in terms of radial Euclidean distance against manually defined ground truth points, with the corresponding success rate of 93% (i.e. 93 out of 100 intervertebral disc spaces were modeled successfully). As the resulting 3D models provide a description of the shape of intervertebral disc spaces in a complete parametric form, morphometric analysis was straightforwardly enabled and allowed the computation of the corresponding

  10. In Vivo Study of Dynamics and Stability of Dendritic Spines on Olfactory Bulb Interneurons in Xenopus laevis Tadpoles

    PubMed Central

    Huang, Yu-Bin; Hu, Chun-Rui; Zhang, Li; Yin, Wu; Hu, Bing

    2015-01-01

    Dendritic spines undergo continuous remodeling during development of the nervous system. Their stability is essential for maintaining a functional neuronal circuit. Spine dynamics and stability of cortical excitatory pyramidal neurons have been explored extensively in mammalian animal models. However, little is known about spiny interneurons in non-mammalian vertebrate models. In the present study, neuronal morphology was visualized by single-cell electroporation. Spiny neurons were surveyed in the Xenopus tadpole brain and observed to be widely distributed in the olfactory bulb and telencephalon. DsRed- or PSD95-GFP-expressing spiny interneurons in the olfactory bulb were selected for in vivo time-lapse imaging. Dendritic protrusions were classified as filopodia, thin, stubby, or mushroom spines based on morphology. Dendritic spines on the interneurons were highly dynamic, especially the filopodia and thin spines. The stubby and mushroom spines were relatively more stable, although their stability significantly decreased with longer observation intervals. The 4 spine types exhibited diverse preferences during morphological transitions from one spine type to others. Sensory deprivation induced by severing the olfactory nerve to block the input of mitral/tufted cells had no significant effects on interneuron spine stability. Hence, a new model was established in Xenopus laevis tadpoles to explore dendritic spine dynamics in vivo. PMID:26485435

  11. The motor learning induces plastic changes in dendritic spines of Purkinje cells from the neocerebellar cortex of the rat.

    PubMed

    González-Tapia, David; Velázquez-Zamora, Dulce A; Olvera-Cortés, María Esther; González-Burgos, Ignacio

    2015-01-01

    The presynaptic stimulatory activity of parallel fibers on the dendritic spines of cerebellar Purkinje cells (PC) has a strong influence on the organization of motor learning. Motor learning has been shown to modify the synapses established on PC dendritic spines but the plastic changes of the different spine types, possibly underlying motor learning, have not been studied. Adult male Sprague-Dawley rats were trained daily for 26 days using an acrobatic paradigm (AC), at the end of which dendritic spine density and the proportion of the different types of spines was assessed. The learning curves of AC rats reflected a robust decrease in the latency for resolution and in the errors committed during the first week of training, which subsequently stabilized until the end of training. Dendritic spine density was greater in these AC rats, reflected in a larger proportion of thin, mushroom and stubby spines. Since thin spines are associated with acquiring novel information whilst mushroom spines are associated with long-term information storage, there appears to be a strong relationship between AC motor learning and consolidation. The increase in stubby spines could be related to the regulation of excitatory stimulation underlying motor overactivity.

  12. Estradiol reduces dendritic spine density in the ventral striatum of female Syrian hamsters.

    PubMed

    Staffend, Nancy A; Loftus, Caroline M; Meisel, Robert L

    2011-01-01

    Estradiol affects a variety of brain regions by modulating physiological and cellular functions as well as neuronal morphology. Within the striatum, estradiol is known to induce physiological and molecular changes, yet estradiol's effects on striatal dendritic morphology have not yet been evaluated. Using ballistic delivery of the lipophilic dye DiI to tissue sections, we were able to evaluate estradiol's effects on striatal morphology in female Syrian hamsters. We found that estradiol significantly decreased spine density within the nucleus accumbens core, with no effect in the nucleus accumbens shell or caudate. Interestingly, estradiol treatment caused a significant deconstruction of spines from more to less mature spine subtypes in both the nucleus accumbens core and shell regardless of changes in spine density. These results are significant in that they offer a novel mechanism for estradiol actions on a wide variety of nucleus accumbens functions such as motivation or reward as well as their pathological consequences (e.g. drug addiction).

  13. The Guanine Nucleotide Exchange Factor (GEF) Asef2 Promotes Dendritic Spine Formation via Rac Activation and Spinophilin-dependent Targeting*

    PubMed Central

    Evans, J. Corey; Robinson, Cristina M.; Shi, Mingjian; Webb, Donna J.

    2015-01-01

    Dendritic spines are actin-rich protrusions that establish excitatory synaptic contacts with surrounding neurons. Reorganization of the actin cytoskeleton is critical for the development and plasticity of dendritic spines, which is the basis for learning and memory. Rho family GTPases are emerging as important modulators of spines and synapses, predominantly through their ability to regulate actin dynamics. Much less is known, however, about the function of guanine nucleotide exchange factors (GEFs), which activate these GTPases, in spine and synapse development. In this study we show that the Rho family GEF Asef2 is found at synaptic sites, where it promotes dendritic spine and synapse formation. Knockdown of endogenous Asef2 with shRNAs impairs spine and synapse formation, whereas exogenous expression of Asef2 causes an increase in spine and synapse density. This effect of Asef2 on spines and synapses is abrogated by expression of GEF activity-deficient Asef2 mutants or by knockdown of Rac, suggesting that Asef2-Rac signaling mediates spine development. Because Asef2 interacts with the F-actin-binding protein spinophilin, which localizes to spines, we investigated the role of spinophilin in Asef2-promoted spine formation. Spinophilin recruits Asef2 to spines, and knockdown of spinophilin hinders spine and synapse formation in Asef2-expressing neurons. Furthermore, inhibition of N-methyl-d-aspartate receptor (NMDA) activity blocks spinophilin-mediated localization of Asef2 to spines. These results collectively point to spinophilin-Asef2-Rac signaling as a novel mechanism for the development of dendritic spines and synapses. PMID:25750125

  14. The guanine nucleotide exchange factor (GEF) Asef2 promotes dendritic spine formation via Rac activation and spinophilin-dependent targeting.

    PubMed

    Evans, J Corey; Robinson, Cristina M; Shi, Mingjian; Webb, Donna J

    2015-04-17

    Dendritic spines are actin-rich protrusions that establish excitatory synaptic contacts with surrounding neurons. Reorganization of the actin cytoskeleton is critical for the development and plasticity of dendritic spines, which is the basis for learning and memory. Rho family GTPases are emerging as important modulators of spines and synapses, predominantly through their ability to regulate actin dynamics. Much less is known, however, about the function of guanine nucleotide exchange factors (GEFs), which activate these GTPases, in spine and synapse development. In this study we show that the Rho family GEF Asef2 is found at synaptic sites, where it promotes dendritic spine and synapse formation. Knockdown of endogenous Asef2 with shRNAs impairs spine and synapse formation, whereas exogenous expression of Asef2 causes an increase in spine and synapse density. This effect of Asef2 on spines and synapses is abrogated by expression of GEF activity-deficient Asef2 mutants or by knockdown of Rac, suggesting that Asef2-Rac signaling mediates spine development. Because Asef2 interacts with the F-actin-binding protein spinophilin, which localizes to spines, we investigated the role of spinophilin in Asef2-promoted spine formation. Spinophilin recruits Asef2 to spines, and knockdown of spinophilin hinders spine and synapse formation in Asef2-expressing neurons. Furthermore, inhibition of N-methyl-d-aspartate receptor (NMDA) activity blocks spinophilin-mediated localization of Asef2 to spines. These results collectively point to spinophilin-Asef2-Rac signaling as a novel mechanism for the development of dendritic spines and synapses. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. The pseudokinase CaMKv is required for the activity-dependent maintenance of dendritic spines

    PubMed Central

    Liang, Zhuoyi; Zhan, Yi; Shen, Yang; Wong, Catherine C. L.; Yates, John R.; Plattner, Florian; Lai, Kwok-On; Ip, Nancy Y.

    2016-01-01

    Dendritic spine stabilization depends on afferent synaptic input and requires changes in actin cytoskeleton dynamics and protein synthesis. However, the underlying molecular mechanism remains unclear. Here we report the identification of ‘calmodulin kinase-like vesicle-associated' (CaMKv), a pseudokinase of the CaMK family with unknown function, as a synaptic protein crucial for dendritic spine maintenance. CaMKv mRNA localizes at dendrites, and its protein synthesis is regulated by neuronal activity. CaMKv function is inhibited upon phosphorylation by cyclin-dependent kinase 5 (Cdk5) at Thr345. Furthermore, CaMKv knockdown in mouse hippocampal CA1 pyramidal neurons impairs synaptic transmission and plasticity in vivo, resulting in hyperactivity and spatial memory impairment. These findings collectively indicate that the precise regulation of CaMKv through activity-dependent synthesis and post-translational phosphorylation is critical for dendritic spine maintenance, revealing an unusual signalling pathway in the regulation of synaptic transmission and brain function that involves a pseudokinase. PMID:27796283

  16. The Gα o Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons

    PubMed Central

    Ramírez, Valerie T.; Ramos-Fernández, Eva; Inestrosa, Nibaldo C.

    2016-01-01

    Mastoparan-7 (Mas-7), an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX-) sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95) clustering in neurites and activates Gα o signaling, increasing the intracellular Ca2+ concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC), c-Jun N-terminal kinase (JNK), and calcium-calmodulin dependent protein kinase IIα (CaMKIIα) after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gα o subunit signaling in the regulation of synapse formation. PMID:26881110

  17. The Gαo Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons.

    PubMed

    Ramírez, Valerie T; Ramos-Fernández, Eva; Inestrosa, Nibaldo C

    2016-01-01

    Mastoparan-7 (Mas-7), an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX-) sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95) clustering in neurites and activates Gα(o) signaling, increasing the intracellular Ca(2+) concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC), c-Jun N-terminal kinase (JNK), and calcium-calmodulin dependent protein kinase IIα (CaMKIIα) after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gα(o) subunit signaling in the regulation of synapse formation.

  18. ANABOLIC-ANDROGENIC STEROIDS DECREASE DENDRITIC SPINE DENSITY IN THE NUCLEUS ACCUMBENS OF MALE RATS

    PubMed Central

    Wallin-Miller, Kathryn; Li, Grace; Kelishani, Diana; Wood, Ruth I.

    2016-01-01

    Recent studies have demonstrated that anabolic-androgenic steroids (AAS) modify cognitive processes such as decision making and behavioral flexibility. However, the neural mechanisms underlying these AAS-induced cognitive changes remain poorly understood. The mesocorticolimbic dopamine (DA) system, particularly the nucleus accumbens (Acb), is important for reward, motivated behavior, and higher cognitive processes such as decision making. Therefore, AAS-induced plasticity in the DA system is a potential structural substrate for the observed cognitive alterations. High doses of testosterone (the most commonly-used AAS) increase dendritic spine density in limbic regions including the amygdala and hippocampus. However, effects on Acb are unknown. This was the focus of the present study. Adolescent male Long-Evans rats were treated chronically for 8 weeks with high-dose testosterone (7.5 mg/kg in water with 13% cyclodextrin) or vehicle sc. Brains were stained by Golgi-Cox to analyze neuronal morphology in medium spiny neurons of the shell region of Acb (AcbSh). 8 weeks of testosterone treatment significantly decreased spine density in AcbSh compared to brains of vehicle-treated rats (F1,14 = 5.455, p<0.05). Testosterone did not significantly affect total spine number, dendritic length, or arborization measured by Sholl analysis. These results show that AAS alter neuronal morphology in AcbSh by decreasing spine density throughout the dendritic tree, and provides a potential mechanism for AAS to modify cognition and decision-making behavior. PMID:27238893

  19. Ablation of ErbB4 from excitatory neurons leads to reduced dendritic spine density in mouse prefrontal cortex

    PubMed Central

    Cooper, Margaret A.; Koleske, Anthony J.

    2014-01-01

    Dendritic spine loss is observed in many psychiatric disorders, including schizophrenia, and likely contributes to the altered sense of reality, disruption of working memory, and attention deficits that characterize these disorders. ErbB4, a member of the EGF family of receptor tyrosine kinases, is genetically associated0020with schizophrenia, suggesting that alterations in ErbB4 function contribute to the disease pathology. Additionally, ErbB4 functions in synaptic plasticity, leading us to hypothesize that disruption of ErbB4 signaling may affect dendritic spine development. We show that dendritic spine density is reduced in the dorsomedial prefrontal cortex of ErbB4 conditional whole-brain knockout mice. We find that ErbB4 localizes to dendritic spines of excitatory neurons in cortical neuronal cultures and is present in synaptic plasma membrane preparations. Finally, we demonstrate that selective ablation of ErbB4 from excitatory neurons leads to a decrease in the proportion of mature spines and an overall reduction in dendritic spine density in the prefrontal cortex of weanling (P21) mice that persists at 2 months of age. These results suggest that ErbB4 signaling in excitatory pyramidal cells is critical for the proper formation and maintenance of dendritic spines in excitatory pyramidal cells. PMID:24752666

  20. Cofilin1 Controls Transcolumnar Plasticity in Dendritic Spines in Adult Barrel Cortex

    PubMed Central

    Tsubota, Tadashi; Okubo-Suzuki, Reiko; Ohashi, Yohei; Tamura, Keita; Ogata, Koshin; Yaguchi, Masae; Matsuyama, Makoto; Inokuchi, Kaoru; Miyashita, Yasushi

    2015-01-01

    During sensory deprivation, the barrel cortex undergoes expansion of a functional column representing spared inputs (spared column), into the neighboring deprived columns (representing deprived inputs) which are in turn shrunk. As a result, the neurons in a deprived column simultaneously increase and decrease their responses to spared and deprived inputs, respectively. Previous studies revealed that dendritic spines are remodeled during this barrel map plasticity. Because cofilin1, a predominant regulator of actin filament turnover, governs both the expansion and shrinkage of the dendritic spine structure in vitro, it hypothetically regulates both responses in barrel map plasticity. However, this hypothesis remains untested. Using lentiviral vectors, we knocked down cofilin1 locally within layer 2/3 neurons in a deprived column. Cofilin1-knocked-down neurons were optogenetically labeled using channelrhodopsin-2, and electrophysiological recordings were targeted to these knocked-down neurons. We showed that cofilin1 knockdown impaired response increases to spared inputs but preserved response decreases to deprived inputs, indicating that cofilin1 dependency is dissociated in these two types of barrel map plasticity. To explore the structural basis of this dissociation, we then analyzed spine densities on deprived column dendritic branches, which were supposed to receive dense horizontal transcolumnar projections from the spared column. We found that spine number increased in a cofilin1-dependent manner selectively in the distal part of the supragranular layer, where most of the transcolumnar projections existed. Our findings suggest that cofilin1-mediated actin dynamics regulate functional map plasticity in an input-specific manner through the dendritic spine remodeling that occurs in the horizontal transcolumnar circuits. These new mechanistic insights into transcolumnar plasticity in adult rats may have a general significance for understanding reorganization of

  1. Reduced Dendritic Spine Density In Auditory Cortex Of Subjects With Schizophrenia

    PubMed Central

    Sweet, Robert A.; Henteleff, Ruth A.; Zhang, Wei; Sampson, Allan R.; Lewis, David A.

    2009-01-01

    Background We have previously identified reductions in mean pyramidal cell somal volume in deep layer 3 of BA 41 and BA 42 and reduced axon terminal density in deep layer 3 of BA 41. In other brain regions demonstrating similar deficits, reduced dendritic spine density has also been identified, leading us to hypothesize that dendritic spine density would also be reduced in BA 41 and BA 42. Because dendritic spines and their excitatory inputs are regulated in tandem, we further hypothesized that spine density would be correlated with axon terminal density. Method We used stereologic methods to quantify a marker of dendritic spines, spinophilin-immunoreactive (SP-IR) puncta, in deep layer 3 of BA 41 and 42 of 15 subjects with schizophrenia, each matched to a normal comparison subject. The effect of long-term haloperidol exposure on SP-IR puncta density was evaluated in non-human primates. Results SP-IR puncta density was significantly lower by 27.2% in deep layer 3 of BA 41 in the schizophrenia subjects, and by 22.2% in deep layer 3 of BA 42. In both BA 41 and 42, SP-IR puncta density was correlated with a marker of axon terminal density, but not with pyramidal cell somal volume. SP-IR puncta density did not differ between haloperidol-exposed and control monkeys. Conclusion Lower SP-IR puncta density in deep layer 3 of BA 41 and 42 of subjects with schizophrenia may reflect concurrent reductions in excitatory afferent input. This may contribute to impairments in auditory sensory processing which are present in subjects with schizophrenia. PMID:18463626

  2. Surgical Navigation Technology Based on Augmented Reality and Integrated 3D Intraoperative Imaging: A Spine Cadaveric Feasibility and Accuracy Study.

    PubMed

    Elmi-Terander, Adrian; Skulason, Halldor; Söderman, Michael; Racadio, John; Homan, Robert; Babic, Drazenko; van der Vaart, Nijs; Nachabe, Rami

    2016-11-01

    A cadaveric laboratory study. The aim of this study was to assess the feasibility and accuracy of thoracic pedicle screw placement using augmented reality surgical navigation (ARSN). Recent advances in spinal navigation have shown improved accuracy in lumbosacral pedicle screw placement but limited benefits in the thoracic spine. 3D intraoperative imaging and instrument navigation may allow improved accuracy in pedicle screw placement, without the use of x-ray fluoroscopy, and thus opens the route to image-guided minimally invasive therapy in the thoracic spine. ARSN encompasses a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D capabilities, integrated optical cameras for augmented reality navigation, and noninvasive patient motion tracking. Two neurosurgeons placed 94 pedicle screws in the thoracic spine of four cadavers using ARSN on one side of the spine (47 screws) and free-hand technique on the contralateral side. X-ray fluoroscopy was not used for either technique. Four independent reviewers assessed the postoperative scans, using the Gertzbein grading. Morphometric measurements of the pedicles axial and sagittal widths and angles, as well as the vertebrae axial and sagittal rotations were performed to identify risk factors for breaches. ARSN was feasible and superior to free-hand technique with respect to overall accuracy (85% vs. 64%, P < 0.05), specifically significant increases of perfectly placed screws (51% vs. 30%, P < 0.05) and reductions in breaches beyond 4 mm (2% vs. 25%, P < 0.05). All morphometric dimensions, except for vertebral body axial rotation, were risk factors for larger breaches when performed with the free-hand method. ARSN without fluoroscopy was feasible and demonstrated higher accuracy than free-hand technique for thoracic pedicle screw placement. N/A.

  3. Detection of Dendritic Spines Using Wavelet-Based Conditional Symmetric Analysis and Regularized Morphological Shared-Weight Neural Networks.

    PubMed

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Zhang, Yudong; Han, Liangxiu; Wu, Jane; Du, Sidan

    2015-01-01

    Identification and detection of dendritic spines in neuron images are of high interest in diagnosis and treatment of neurological and psychiatric disorders (e.g., Alzheimer's disease, Parkinson's diseases, and autism). In this paper, we have proposed a novel automatic approach using wavelet-based conditional symmetric analysis and regularized morphological shared-weight neural networks (RMSNN) for dendritic spine identification involving the following steps: backbone extraction, localization of dendritic spines, and classification. First, a new algorithm based on wavelet transform and conditional symmetric analysis has been developed to extract backbone and locate the dendrite boundary. Then, the RMSNN has been proposed to classify the spines into three predefined categories (mushroom, thin, and stubby). We have compared our proposed approach against the existing methods. The experimental result demonstrates that the proposed approach can accurately locate the dendrite and accurately classify the spines into three categories with the accuracy of 99.1% for "mushroom" spines, 97.6% for "stubby" spines, and 98.6% for "thin" spines.

  4. Detection of Dendritic Spines Using Wavelet-Based Conditional Symmetric Analysis and Regularized Morphological Shared-Weight Neural Networks

    PubMed Central

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Zhang, Yudong; Han, Liangxiu; Wu, Jane; Du, Sidan

    2015-01-01

    Identification and detection of dendritic spines in neuron images are of high interest in diagnosis and treatment of neurological and psychiatric disorders (e.g., Alzheimer's disease, Parkinson's diseases, and autism). In this paper, we have proposed a novel automatic approach using wavelet-based conditional symmetric analysis and regularized morphological shared-weight neural networks (RMSNN) for dendritic spine identification involving the following steps: backbone extraction, localization of dendritic spines, and classification. First, a new algorithm based on wavelet transform and conditional symmetric analysis has been developed to extract backbone and locate the dendrite boundary. Then, the RMSNN has been proposed to classify the spines into three predefined categories (mushroom, thin, and stubby). We have compared our proposed approach against the existing methods. The experimental result demonstrates that the proposed approach can accurately locate the dendrite and accurately classify the spines into three categories with the accuracy of 99.1% for “mushroom” spines, 97.6% for “stubby” spines, and 98.6% for “thin” spines. PMID:26692046

  5. Adolescent bisphenol-A exposure decreases dendritic spine density: role of sex and age.

    PubMed

    Bowman, Rachel E; Luine, Victoria; Khandaker, Hameda; Villafane, Joseph J; Frankfurt, Maya

    2014-11-01

    Bisphenol-A (BPA), a common environmental endocrine disruptor, modulates estrogenic, androgenic, and antiandrogenic effects throughout the lifespan. We recently showed that low dose BPA exposure during adolescence increases anxiety and impairs spatial memory independent of sex. In this study, six week old Sprague Dawley rats (n=24 males, n=24 females) received daily subcutaneous injections (40 µg/kg bodyweight) of BPA or vehicle for one week. Serum corticosterone levels in response to a 1 h restraint stress and spine density were examined at age 7 (cohort 1) and 11 (cohort 2) weeks. Adolescent BPA exposure did not alter stress dependent corticosterone responses but decreased spine density on apical and basal dendrites of pyramidal cells in the medial prefrontal cortex (mPFC) and hippocampal CA1 region (CA1). Sex differences in spine density were observed on basal dendrites of the mPFC and CA1 with females having greater spine density than males. This sex difference was further augmented by both age and treatment, with results indicating that BPA-dependent decreases in spine density were more pronounced in males than females on mPFC basal dendrites. Importantly, the robust neuronal alterations were observed in animals exposed to BPA levels below the current U.S.E.P.A. recommended safe daily limit. These results are the first demonstrating that BPA given during adolescence leads to enduring effects on neural morphology at adulthood. Given that humans are routinely exposed to low levels of BPA through a variety of sources, the decreased spine density reported in both male and female rats after BPA exposure warrants further investigation.

  6. Cerebellar dentate nuclei lesions alter prefrontal cortex dendritic spine morphology.

    PubMed

    Bauer, David J; Peterson, Todd C; Swain, Rodney A

    2014-01-28

    Anatomical tracing studies in primates have revealed neural tracts from the cerebellar dentate nuclei to prefrontal cortex, implicating a cerebellar role in nonmotor processes. Experiments in rats examining the functional role of this cerebellothalamocortical pathway have demonstrated the development of visuospatial and motivational deficits following lesions of the dentate nuclei, in the absence of motor impairment. These behavioral deficits possibly occur due to structural modifications of the cerebral cortex secondary to loss of cerebellar input. The current study characterized morphological alterations in prefrontal cortex important for visuospatial and motivational processes following bilateral cerebellar dentate nuclei lesions. Rats received either bilateral electrolytic cerebellar dentate nuclei lesions or sham surgery followed by a 30-day recovery. Randomly selected Golgi-impregnated neurons in prefrontal cortex were examined for analysis. Measures of branch length and spine density revealed no differences between lesioned and sham rats in either apical or basilar arbors; however, the proportion of immature to mature spines significantly decreased in lesioned rats as compared to sham controls, with reductions of 33% in the basilar arbor and 28% in the apical arbor. Although expected pruning of branches and spines did not occur, the results are consistent with the hypothesis that cerebellar lesions influence prefrontal morphology and support the possibility that functional deficits following cerebellar dentate nuclei lesions are related to prefrontal morphological alteration.

  7. Actin Capping Protein is required for Dendritic Spine Development and Synapse Formation

    PubMed Central

    Fan, Yanjie; Tang, Xin; Vitriol, Eric; Chen, Gong; Zheng, James Q.

    2011-01-01

    Dendritic spines serve as the postsynaptic platform for most excitatory synapses in the mammalian brain and their shape and size are tightly correlated with synaptic strength. The actin cytoskeleton plays a crucial role in the spine structure and its modifications during synapse development and plasticity, but the underlying regulatory mechanisms remain to be elucidated. Here we report that actin capping protein (CP), a regulator of actin filament growth, plays an essential role for spine development and synapse formation. We found that CP expression in rat hippocampus is elevated at and after the stage of substantial synapse formation. CP knockdown in hippocampal cultures resulted in a marked decline in the spine density accompanied by increased filopodia-like protrusions. Moreover, the spines of CP knockdown neurons exhibited an altered morphology, highlighted by multiple thin filopodia-like protrusions emerging from the spine head. Finally, the number of functional synapses was reduced by CP knockdown as evidenced by a reduction in the density of paired pre- and postsynaptic markers and in the frequency of miniature excitatory postsynaptic currents. These findings indicate that capping of actin filaments by CP represents an essential step for the remodeling of the actin architecture underlying spine morphogenesis and synaptic formation during development. PMID:21752999

  8. Actinin-4 Governs Dendritic Spine Dynamics and Promotes Their Remodeling by Metabotropic Glutamate Receptors*

    PubMed Central

    Kalinowska, Magdalena; Chávez, Andrés E.; Lutzu, Stefano; Castillo, Pablo E.; Bukauskas, Feliksas F.; Francesconi, Anna

    2015-01-01

    Dendritic spines are dynamic, actin-rich protrusions in neurons that undergo remodeling during neuronal development and activity-dependent plasticity within the central nervous system. Although group 1 metabotropic glutamate receptors (mGluRs) are critical for spine remodeling under physiopathological conditions, the molecular components linking receptor activity to structural plasticity remain unknown. Here we identify a Ca2+-sensitive actin-binding protein, α-actinin-4, as a novel group 1 mGluR-interacting partner that orchestrates spine dynamics and morphogenesis in primary neurons. Functional silencing of α-actinin-4 abolished spine elongation and turnover stimulated by group 1 mGluRs despite intact surface receptor expression and downstream ERK1/2 signaling. This function of α-actinin-4 in spine dynamics was underscored by gain-of-function phenotypes in untreated neurons. Here α-actinin-4 induced spine head enlargement, a morphological change requiring the C-terminal domain of α-actinin-4 that binds to CaMKII, an interaction we showed to be regulated by group 1 mGluR activation. Our data provide mechanistic insights into spine remodeling by metabotropic signaling and identify α-actinin-4 as a critical effector of structural plasticity within neurons. PMID:25944910

  9. Two-Photon Optical Interrogation of Individual Dendritic Spines with Caged Dopamine

    PubMed Central

    2013-01-01

    We introduce a novel caged dopamine compound (RuBi-Dopa) based on ruthenium photochemistry. RuBi-Dopa has a high uncaging efficiency and can be released with visible (blue-green) and IR light in a two-photon regime. We combine two-photon photorelease of RuBi-Dopa with two-photon calcium imaging for an optical imaging and manipulation of dendritic spines in living brain slices, demonstrating that spines can express functional dopamine receptors. This novel compound allows mapping of functional dopamine receptors in living brain tissue with exquisite spatial resolution. PMID:23672485

  10. EVIDENCE OF CELL-NONAUTONOMOUS CHANGES IN DENDRITE AND DENDRITIC SPINE MORPHOLOGY IN THE MET-SIGNALING DEFICIENT MOUSE FOREBRAIN

    PubMed Central

    Judson, Matthew C.; Eagleson, Kathie L.; Wang, Lily; Levitt, Pat

    2010-01-01

    Human genetic findings and murine neuroanatomical expression mapping have intersected to implicate Met receptor tyrosine kinase signaling in the development of forebrain circuits controlling social and emotional behaviors that are atypical in autism spectrum disorders (ASD). To clarify roles for Met signaling during forebrain circuit development in vivo, we generated mutant mice (Emx1Cre/Metfx/fx) with an Emx1-Cre-driven deletion of signaling-competent Met in dorsal pallially-derived forebrain neurons. Morphometric analyses of Lucifer Yellow-injected pyramidal neurons in postnatal day 40 anterior cingulate cortex (ACC) revealed no statistically significant changes in total dendritic length, but a selective reduction in apical arbor length distal to the soma in Emx1Cre/Metfx/fx neurons relative to wild type, consistent with a decrease in the total tissue volume sampled by individual arbors in the cortex. The effects on dendritic structure appear to be circuit-selective, as basal arbor length was increased in Emx1Cre/Metfx/fx layer 2/3 neurons. Spine number was not altered on Emx1Cre/Metfx/fx pyramidal cell populations studied, but spine head volume was significantly increased (~20%). Cell-nonautonomous, circuit-level influences of Met signaling on dendritic development were confirmed by studies of medium spiny neurons (MSN), which do not express Met, but receive Met-expressing corticostriatal afferents during development. Emx1Cre/Metfx/fx MSN exhibited robust increases in total arbor length (~20%). Like in the neocortex, average spine head volume was also increased (~12%). These data demonstrate that a developmental loss of presynaptic Met receptor signaling can affect postsynaptic morphogenesis and suggest a mechanism whereby attenuated Met signaling could disrupt both local and long-range connectivity within circuits relevant to ASD. PMID:20853516

  11. Attenuation of dendritic spine density in the perirhinal cortex following 17β-Estradiol replacement in the rat.

    PubMed

    Gervais, Nicole J; Mumby, Dave G; Brake, Wayne G

    2015-11-01

    Intraperirhinal cortex infusion of 17-β estradiol (E2) impairs object-recognition memory. However, it is not currently known whether this hormone modulates synaptic plasticity in this structure. Most excitatory synapses in the central nervous system are located on dendritic spines, and elevated E2 levels influence the density of these spines in several brain areas. The goal of the present study was to determine whether differences in dendritic spine density in the perirhinal cortex are observed following high E2 replacement in ovariectomized rats. The density of total spines, and mushroom-shaped (i.e. mature) spines were compared between a high E2 replacement (10 µg/kg/day, s.c.) and a no replacement condition. The perirhinal cortex is subdivided into Broadmann's area 35 and 36 and so group comparisons were made within each sub-region separately. High E2 replacement resulted in lower density of mushroom-shaped spines in area 35 relative to no replacement. There was no effect of high E2 replacement on dendritic spine density in area 36. These findings are consistent with the idea that higher E2 levels reduce dendritic spine density in area 35, which may result from spine shrinkage, or reduced synapse formation. This study provides preliminary evidence for a mechanism through which E2 may impair object-recognition memory. © 2015 Wiley Periodicals, Inc.

  12. Known-component 3D-2D registration for quality assurance of spine surgery pedicle screw placement

    PubMed Central

    Uneri, A; De Silva, T; Stayman, JW; Kleinszig, G; Vogt, S; Khanna, AJ; Gokaslan, ZL; Wolinsky, J-P; Siewerdsen, JH

    2015-01-01

    Purpose A 3D-2D image registration method is presented that exploits knowledge of interventional devices (e.g., K-wires or spine screws – referred to as “known components”) to extend the functionality of intraoperative radiography/fluoroscopy by providing quantitative measurement and quality assurance (QA) of the surgical product. Methods The known-component registration (KC-Reg) algorithm uses robust 3D-2D registration combined with 3D component models of surgical devices known to be present in intraoperative 2D radiographs. Component models were investigated that vary in fidelity from simple parametric models (e.g., approximation of a screw as a simple cylinder, referred to as “parametrically-known” component [pKC] registration) to precise models based on device-specific CAD drawings (referred to as “exactly-known” component [eKC] registration). 3D-2D registration from three intraoperative radiographs was solved using the covariance matrix adaptation evolution strategy (CMA-ES) to maximize image-gradient similarity, relating device placement relative to 3D preoperative CT of the patient. Spine phantom and cadaver studies were conducted to evaluate registration accuracy and demonstrate QA of the surgical product by verification of the type of devices delivered and conformance within the “acceptance window” of the spinal pedicle. Results Pedicle screws were successfully registered to radiographs acquired from a mobile C-arm, providing TRE 1–4 mm and <5° using simple parametric (pKC) models, further improved to <1 mm and <1° using eKC registration. Using advanced pKC models, screws that did not match the device models specified in the surgical plan were detected with an accuracy of >99%. Visualization of registered devices relative to surgical planning and the pedicle acceptance window provided potentially valuable QA of the surgical product and reliable detection of pedicle screw breach. Conclusions 3D-2D registration combined with 3D models

  13. Known-component 3D-2D registration for quality assurance of spine surgery pedicle screw placement.

    PubMed

    Uneri, A; De Silva, T; Stayman, J W; Kleinszig, G; Vogt, S; Khanna, A J; Gokaslan, Z L; Wolinsky, J-P; Siewerdsen, J H

    2015-10-21

    A 3D-2D image registration method is presented that exploits knowledge of interventional devices (e.g. K-wires or spine screws-referred to as 'known components') to extend the functionality of intraoperative radiography/fluoroscopy by providing quantitative measurement and quality assurance (QA) of the surgical product. The known-component registration (KC-Reg) algorithm uses robust 3D-2D registration combined with 3D component models of surgical devices known to be present in intraoperative 2D radiographs. Component models were investigated that vary in fidelity from simple parametric models (e.g. approximation of a screw as a simple cylinder, referred to as 'parametrically-known' component [pKC] registration) to precise models based on device-specific CAD drawings (referred to as 'exactly-known' component [eKC] registration). 3D-2D registration from three intraoperative radiographs was solved using the covariance matrix adaptation evolution strategy (CMA-ES) to maximize image-gradient similarity, relating device placement relative to 3D preoperative CT of the patient. Spine phantom and cadaver studies were conducted to evaluate registration accuracy and demonstrate QA of the surgical product by verification of the type of devices delivered and conformance within the 'acceptance window' of the spinal pedicle. Pedicle screws were successfully registered to radiographs acquired from a mobile C-arm, providing TRE 1-4 mm and  <5° using simple parametric (pKC) models, further improved to  <1 mm and  <1° using eKC registration. Using advanced pKC models, screws that did not match the device models specified in the surgical plan were detected with an accuracy of  >99%. Visualization of registered devices relative to surgical planning and the pedicle acceptance window provided potentially valuable QA of the surgical product and reliable detection of pedicle screw breach. 3D-2D registration combined with 3D models of known surgical devices offers a

  14. Known-component 3D-2D registration for quality assurance of spine surgery pedicle screw placement

    NASA Astrophysics Data System (ADS)

    Uneri, A.; De Silva, T.; Stayman, J. W.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Gokaslan, Z. L.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2015-10-01

    A 3D-2D image registration method is presented that exploits knowledge of interventional devices (e.g. K-wires or spine screws—referred to as ‘known components’) to extend the functionality of intraoperative radiography/fluoroscopy by providing quantitative measurement and quality assurance (QA) of the surgical product. The known-component registration (KC-Reg) algorithm uses robust 3D-2D registration combined with 3D component models of surgical devices known to be present in intraoperative 2D radiographs. Component models were investigated that vary in fidelity from simple parametric models (e.g. approximation of a screw as a simple cylinder, referred to as ‘parametrically-known’ component [pKC] registration) to precise models based on device-specific CAD drawings (referred to as ‘exactly-known’ component [eKC] registration). 3D-2D registration from three intraoperative radiographs was solved using the covariance matrix adaptation evolution strategy (CMA-ES) to maximize image-gradient similarity, relating device placement relative to 3D preoperative CT of the patient. Spine phantom and cadaver studies were conducted to evaluate registration accuracy and demonstrate QA of the surgical product by verification of the type of devices delivered and conformance within the ‘acceptance window’ of the spinal pedicle. Pedicle screws were successfully registered to radiographs acquired from a mobile C-arm, providing TRE 1-4 mm and  <5° using simple parametric (pKC) models, further improved to  <1 mm and  <1° using eKC registration. Using advanced pKC models, screws that did not match the device models specified in the surgical plan were detected with an accuracy of  >99%. Visualization of registered devices relative to surgical planning and the pedicle acceptance window provided potentially valuable QA of the surgical product and reliable detection of pedicle screw breach. 3D-2D registration combined with 3D models of known surgical

  15. nArgBP2 regulates excitatory synapse formation by controlling dendritic spine morphology.

    PubMed

    Lee, Sang-Eun; Kim, Yoonju; Han, Jeong-Kyu; Park, Hoyong; Lee, Unghwi; Na, Myeongsu; Jeong, Soomin; Chung, ChiHye; Cestra, Gianluca; Chang, Sunghoe

    2016-06-14

    Neural Abelson-related gene-binding protein 2 (nArgBP2) was originally identified as a protein that directly interacts with synapse-associated protein 90/postsynaptic density protein 95-associated protein 3 (SAPAP3), a postsynaptic scaffolding protein critical for the assembly of glutamatergic synapses. Although genetic deletion of nArgBP2 in mice leads to manic/bipolar-like behaviors resembling many aspects of symptoms in patients with bipolar disorder, the actual function of nArgBP2 at the synapse is completely unknown. Here, we found that the knockdown (KD) of nArgBP2 by specific small hairpin RNAs (shRNAs) resulted in a dramatic change in dendritic spine morphology. Reintroducing shRNA-resistant nArgBP2 reversed these defects. In particular, nArgBP2 KD impaired spine-synapse formation such that excitatory synapses terminated mostly at dendritic shafts instead of spine heads in spiny neurons, although inhibitory synapse formation was not affected. nArgBP2 KD further caused a marked increase of actin cytoskeleton dynamics in spines, which was associated with increased Wiskott-Aldrich syndrome protein-family verprolin homologous protein 1 (WAVE1)/p21-activated kinase (PAK) phosphorylation and reduced activity of cofilin. These effects of nArgBP2 KD in spines were rescued by inhibiting PAK or activating cofilin combined with sequestration of WAVE. Together, our results suggest that nArgBP2 functions to regulate spine morphogenesis and subsequent spine-synapse formation at glutamatergic synapses. They also raise the possibility that the aberrant regulation of synaptic actin filaments caused by reduced nArgBP2 expression may contribute to the manifestation of the synaptic dysfunction observed in manic/bipolar disorder.

  16. Effect of Ovarian Hormones on Genes Promoting Dendritic Spines In Laser Captured Serotonin Neurons From Macaques

    PubMed Central

    Bethea, Cynthia L.; Reddy, Arubala P.

    2009-01-01

    Dendritic spines are the elementary structural units of neuronal plasticity and the cascades that promote dendrite spine remodeling center on Rho GTPases and downstream effectors of actin dynamics. In a model of hormone replacement therapy (HT), we sought the effect of estradiol (E) and progesterone (P) on gene expression in these cascades in laser captured serotonin neurons from rhesus macaques with cDNA array analysis. Spayed rhesus macaques were treated with either placebo, E or E+P via Silastic implant for 1 month prior to euthanasia after which the midbrain was obtained, sectioned and immunostained for TPH. TPH-positive neurons were laser captured using an Arcturus Laser Dissection Microscope (PixCell II). RNA from laser captured serotonin neurons (n=2 animals/treatment) was hybridized to Rhesus Affymetrix GeneChips. There was a significant change in 744 probe sets (ANOVA, p < 0.05), but 10,493 probe sets exhibited a 2-fold or greater change. Pivotal changes in pathways leading to dendrite spine proliferation and transformation included 2-fold or greater increases in expression of the Rho GTPases called CDC42, Rac1 and RhoA. In addition, 2-fold or greater increases occurred in downstream effectors of actin dynamics including PAK1, ROCK, PIP5K, IRSp53, WASP, WAVE, MLC, cofilin, gelsolin, profilin and 3 subunits of ARP2/3. Finally, 2-fold or greater decreases occurred in CRIPAK, LIMK2 and MLCK. The regulation of RhoA, Rac1, CDC42, ROCK, PIP5k, IRSp53, WASP, WAVE, LIMK2, CRIPAK1, MLCK, ARP2/3 subunit 3, gelsolin, profilin and cofilin was confirmed with nested qRT-PCR on laser captured RNA (n=3 animals/treatment). The data indicate that ovarian steroids target gene expression of the Rho GTPases and pivotal downstream proteins that in turn, would promote dendritic spine proliferation and stabilization on serotonin neurons of the dorsal raphe nucleus. PMID:19687787

  17. Hybrid nickel manganese oxide nanosheet-3D metallic dendrite percolation network electrodes for high-rate electrochemical energy storage.

    PubMed

    Nguyen, Tuyen; Eugénio, Sónia; Boudard, Michel; Rapenne, Laetitia; Carmezim, M João; Silva, Teresa M; Montemor, M Fátima

    2015-08-07

    This work reports the fabrication, by electrodeposition and post-thermal annealing, of hybrid electrodes for high rate electrochemical energy storage composed of nickel manganese oxide (Ni0.86Mn0.14O) nanosheets over 3D open porous dendritic NiCu foams. The hybrid electrodes are made of two different percolation networks of nanosheets and dendrites, and exhibit a specific capacitance value of 848 F g(-1) at 1 A g(-1). The electrochemical tests revealed that the electrodes display an excellent rate capability, characterized by capacitance retention of approximately 83% when the applied current density increases from 1 A g(-1) to 20 A g(-1). The electrodes also evidenced high charge-discharge cycling stability, which attained 103% after 1000 cycles.

  18. Actin-Dependent Alterations of Dendritic Spine Morphology in Shankopathies

    PubMed Central

    Sarowar, Tasnuva

    2016-01-01

    Shank proteins (Shank1, Shank2, and Shank3) act as scaffolding molecules in the postsynaptic density of many excitatory neurons. Mutations in SHANK genes, in particular SHANK2 and SHANK3, lead to autism spectrum disorders (ASD) in both human and mouse models. Shank3 proteins are made of several domains—the Shank/ProSAP N-terminal (SPN) domain, ankyrin repeats, SH3 domain, PDZ domain, a proline-rich region, and the sterile alpha motif (SAM) domain. Via various binding partners of these domains, Shank3 is able to bind and interact with a wide range of proteins including modulators of small GTPases such as RICH2, a RhoGAP protein, and βPIX, a RhoGEF protein for Rac1 and Cdc42, actin binding proteins and actin modulators. Dysregulation of all isoforms of Shank proteins, but especially Shank3, leads to alterations in spine morphogenesis, shape, and activity of the synapse via altering actin dynamics. Therefore, here, we highlight the role of Shank proteins as modulators of small GTPases and, ultimately, actin dynamics, as found in multiple in vitro and in vivo models. The failure to mediate this regulatory role might present a shared mechanism in the pathophysiology of autism-associated mutations, which leads to dysregulation of spine morphogenesis and synaptic signaling. PMID:27795858

  19. State-dependent diffusion of actin-depolymerizing factor/cofilin underlies the enlargement and shrinkage of dendritic spines

    PubMed Central

    Noguchi, Jun; Hayama, Tatsuya; Watanabe, Satoshi; Ucar, Hasan; Yagishita, Sho; Takahashi, Noriko; Kasai, Haruo

    2016-01-01

    Dendritic spines are the postsynaptic sites of most excitatory synapses in the brain, and spine enlargement and shrinkage give rise to long-term potentiation and depression of synapses, respectively. Because spine structural plasticity is accompanied by remodeling of actin scaffolds, we hypothesized that the filamentous actin regulatory protein cofilin plays a crucial role in this process. Here we investigated the diffusional properties of cofilin, the actin-severing and depolymerizing actions of which are activated by dephosphorylation. Cofilin diffusion was measured using fluorescently labeled cofilin fusion proteins and two-photon imaging. We show that cofilins are highly diffusible along dendrites in the resting state. However, during spine enlargement, wild-type cofilin and a phosphomimetic cofilin mutant remain confined to the stimulated spine, whereas a nonphosphorylatable mutant does not. Moreover, inhibition of cofilin phosphorylation with a competitive peptide disables spine enlargement, suggesting that phosphorylated-cofilin accumulation is a key regulator of enlargement, which is localized to individual spines. Conversely, spine shrinkage spreads to neighboring spines, even though triggered by weaker stimuli than enlargement. Diffusion of exogenous cofilin injected into a pyramidal neuron soma causes spine shrinkage and reduced PSD95 in spines, suggesting that diffusion of dephosphorylated endogenous cofilin underlies the spreading of spine shrinkage and long-term depression. PMID:27595610

  20. Aerosol Delivery of Functionalized Gold Nanoparticles Target and Activate Dendritic Cells in a 3D Lung Cellular Model.

    PubMed

    Fytianos, Kleanthis; Chortarea, Savvina; Rodriguez-Lorenzo, Laura; Blank, Fabian; von Garnier, Christophe; Petri-Fink, Alke; Rothen-Rutishauser, Barbara

    2017-01-24

    Nanocarrier design combined with pulmonary drug delivery holds great promise for the treatment of respiratory tract disorders. In particular, targeting of dendritic cells that are key immune cells to enhance or suppress an immune response in the lung is a promising approach for the treatment of allergic diseases. Fluorescently encoded poly(vinyl alcohol) (PVA)-coated gold nanoparticles, functionalized with either negative (-COO(-)) or positive (-NH3(+)) surface charges, were functionalized with a DC-SIGN antibody on the particle surface, enabling binding to a dendritic cell surface receptor. A 3D coculture model consisting of epithelial and immune cells (macrophages and dendritic cells) mimicking the human lung epithelial tissue barrier was employed to assess the effects of aerosolized AuNPs. PVA-NH2 AuNPs showed higher uptake compared to that of their -COOH counterparts, with the highest uptake recorded in macrophages, as shown by flow cytometry. None of the AuNPs induced cytotoxicity or necrosis or increased cytokine secretion, whereas only PVA-NH2 AuNPs induced higher apoptosis levels. DC-SIGN AuNPs showed significantly increased uptake by monocyte-derived dendritic cells (MDDCs) with subsequent activation compared to non-antibody-conjugated control AuNPs, independent of surface charge. Our results show that DC-SIGN conjugation to the AuNPs enhanced MDDC targeting and activation in a complex 3D lung cell model. These findings highlight the potential of immunoengineering approaches to the targeting and activation of immune cells in the lung by nanocarriers.

  1. Nanoscale segregation of actin nucleation and elongation factors determines dendritic spine protrusion

    PubMed Central

    Chazeau, Anaël; Mehidi, Amine; Nair, Deepak; Gautier, Jérémie J; Leduc, Cécile; Chamma, Ingrid; Kage, Frieda; Kechkar, Adel; Thoumine, Olivier; Rottner, Klemens; Choquet, Daniel; Gautreau, Alexis; Sibarita, Jean-Baptiste; Giannone, Grégory

    2014-01-01

    Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super-resolution imaging, we revealed the nanoscale organization and dynamics of branched F-actin regulators in spines. Branched F-actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger-like protrusions. This spatial segregation differs from lamellipodia where both branched F-actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex. In contrast, filament elongators like VASP and formin-like protein-2 move outwards from the PSD with protrusion tips. Accordingly, Arp2/3 complexes associated with F-actin are immobile and surround the PSD. Arp2/3 and Rac1 GTPase converge to the PSD, respectively, by cytosolic and free-diffusion on the membrane. Enhanced Rac1 activation and Shank3 over-expression, both associated with spine enlargement, induce delocalization of the WAVE complex from the PSD. Thus, the specific localization of branched F-actin regulators in spines might be reorganized during spine morphological remodeling often associated with synaptic plasticity. PMID:25293574

  2. 3D-modeling of the spine using EOS imaging system: Inter-reader reproducibility and reliability

    PubMed Central

    Rehm, Johannes; Germann, Thomas; Akbar, Michael; Pepke, Wojciech; Kauczor, Hans-Ulrich; Weber, Marc-André; Spira, Daniel

    2017-01-01

    Objectives To retrospectively assess the interreader reproducibility and reliability of EOS 3D full spine reconstructions in patients with adolescent idiopathic scoliosis (AIS). Methods 73 patients with mean age of 17 years and a moderate AIS (median Cobb Angle 18.2°) obtained low-dose standing biplanar radiographs with EOS. Two independent readers performed “full spine” 3D reconstructions of the spine with the “full-spine” method adjusting the bone contour of every thoracic and lumbar vertebra (Th1-L5). Interreader reproducibility was assessed regarding rotation of every single vertebra in the coronal (i.e. frontal), sagittal (i.e. lateral), and axial plane, T1/T12 kyphosis, T4/T12 kyphosis, L1/L5 lordosis, L1/S1 lordosis and pelvic parameters. Radiation exposure, scan-time and 3D reconstruction time were recorded. Results Interclass correlation (ICC) ranged between 0.83 and 0.98 for frontal vertebral rotation, between 0.94 and 0.99 for lateral vertebral rotation and between 0.51 and 0.88 for axial vertebral rotation. ICC was 0.92 for T1/T12 kyphosis, 0.95 for T4/T12 kyphosis, 0.90 for L1/L5 lordosis, 0.85 for L1/S1 lordosis, 0.97 for pelvic incidence, 0.96 for sacral slope, 0.98 for sagittal pelvic tilt and 0.94 for lateral pelvic tilt. The mean time for reconstruction was 14.9 minutes (reader 1: 14.6 minutes, reader 2: 15.2 minutes, p<0.0001). The mean total absorbed dose was 593.4μGy ±212.3 per patient. Conclusion EOS “full spine” 3D angle measurement of vertebral rotation proved to be reliable and was performed in an acceptable reconstruction time. Interreader reproducibility of axial rotation was limited to some degree in the upper and middle thoracic spine due the obtuse angulation of the pedicles and the processi spinosi in the frontal view somewhat complicating their delineation. PMID:28152019

  3. Of microtubules and memory: implications for microtubule dynamics in dendrites and spines

    PubMed Central

    Dent, Erik W.

    2017-01-01

    Microtubules (MTs) are cytoskeletal polymers composed of repeating subunits of tubulin that are ubiquitously expressed in eukaryotic cells. They undergo a stochastic process of polymerization and depolymerization from their plus ends termed dynamic instability. MT dynamics is an ongoing process in all cell types and has been the target for the development of several useful anticancer drugs, which compromise rapidly dividing cells. Recent studies also suggest that MT dynamics may be particularly important in neurons, which develop a highly polarized morphology, consisting of a single axon and multiple dendrites that persist throughout adulthood. MTs are especially dynamic in dendrites and have recently been shown to polymerize directly into dendritic spines, the postsynaptic compartment of excitatory neurons in the CNS. These transient polymerization events into dendritic spines have been demonstrated to play important roles in synaptic plasticity in cultured neurons. Recent studies also suggest that MT dynamics in the adult brain function in the essential process of learning and memory and may be compromised in degenerative diseases, such as Alzheimer’s disease. This raises the possibility of targeting MT dynamics in the design of new therapeutic agents. PMID:28035040

  4. Chronic Social Defeat Stress Modulates Dendritic Spines Structural Plasticity in Adult Mouse Frontal Association Cortex

    PubMed Central

    Shu, Yu

    2017-01-01

    Chronic stress is associated with occurrence of many mental disorders. Previous studies have shown that dendrites and spines of pyramidal neurons of the prefrontal cortex undergo drastic reorganization following chronic stress experience. So the prefrontal cortex is believed to play a key role in response of neural system to chronic stress. However, how stress induces dynamic structural changes in neural circuit of prefrontal cortex remains unknown. In the present study, we examined the effects of chronic social defeat stress on dendritic spine structural plasticity in the mouse frontal association (FrA) cortex in vivo using two-photon microscopy. We found that chronic stress altered spine dynamics in FrA and increased the connectivity in FrA neural circuits. We also found that the changes in spine dynamics in FrA are correlated with the deficit of sucrose preference in defeated mice. Our findings suggest that chronic stress experience leads to adaptive change in neural circuits that may be important for encoding stress experience related memory and anhedonia. PMID:28197343

  5. Distribution of NMDA and AMPA receptor subunits at thalamo-amygdaloid dendritic spines.

    PubMed

    Radley, Jason J; Farb, Claudia R; He, Yong; Janssen, William G M; Rodrigues, Sarina M; Johnson, Luke R; Hof, Patrick R; LeDoux, Joseph E; Morrison, John H

    2007-02-23

    Synapses onto dendritic spines in the lateral amygdala formed by afferents from the auditory thalamus represent a site of plasticity in Pavlovian fear conditioning. Previous work has demonstrated that thalamic afferents synapse onto LA spines expressing glutamate receptor (GluR) subunits, but the GluR subunit distribution at the synapse and within the cytoplasm has not been characterized. Therefore, we performed a quantitative analysis for alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor subunits GluR2 and GluR3 and N-methyl-D-aspartate (NMDA) receptor subunits NR1 and NR2B by combining anterograde labeling of thalamo-amygdaloid afferents with postembedding immunoelectron microscopy for the GluRs in adult rats. A high percentage of thalamo-amygdaloid spines was immunoreactive for GluR2 (80%), GluR3 (83%), and NR1 (83%), while a smaller proportion of spines expressed NR2B (59%). To compare across the various subunits, the cytoplasmic to synaptic ratios of GluRs were measured within thalamo-amygdaloid spines. Analyses revealed that the cytoplasmic pool of GluR2 receptors was twice as large compared to the GluR3, NR1, and NR2B subunits. Our data also show that in the adult brain, the NR2B subunit is expressed in the majority of in thalamo-amygdaloid spines and that within these spines, the various GluRs are differentially distributed between synaptic and non-synaptic sites. The prevalence of the NR2B subunit in thalamo-amygdaloid spines provides morphological evidence supporting its role in the fear conditioning circuit while the differential distribution of the GluR subtypes may reflect distinct roles for their involvement in this circuitry and synaptic plasticity.

  6. Altered cortical CDC42 signaling pathways in schizophrenia: Implications for dendritic spine deficits

    PubMed Central

    Ide, Masayuki; Lewis, David A.

    2010-01-01

    Background Spine density on the basilar dendrites of pyramidal neurons is lower in layer 3, but not in layers 5-6, in the dorsolateral prefrontal cortex (DLPFC) of subjects with schizophrenia. The expression of CDC42 (cell division cycle 42), a RhoGTPase which regulates the outgrowth of the actin cytoskeleton and promotes spine formation, is also lower in schizophrenia; however, CDC42 mRNA is lower across layers 3-6, suggesting that other lamina-specific molecular alterations are critical for the spine deficits in the illness. The CDC42 effector proteins 3 and 4 (CDC42EP3, CDC42EP4) are preferentially expressed in DLPFC layers 2 and 3, and CDC42EP3 appears to assemble septin filaments in spine necks. Therefore, alterations in CDC42EP3 could contribute to the lamina-specific spine deficits in schizophrenia. Methods We measured transcript levels of CDC42, CDC42EP3, CDC42EP4, their interacting proteins [septins (SEPT2, 3, 5, 6, 7, 8 and 11), anillin], and other spine-specific proteins (spinophilin, PSD-95 and synaptopodin) in the DLPFC from 31 subjects with schizophrenia and matched normal comparison subjects. Results The expression of CDC42EP3 mRNA was significantly increased by 19.7%, and SEPT7 mRNA was significantly decreased by 6.9% in subjects with schizophrenia. Cortical levels of CDC42EP3 and SEPT7 mRNAs were not altered in monkeys chronically exposed to antipsychotic medications. Conclusions Activated CDC42 is thought to transiently disrupt septin filaments in spine necks, allowing the molecular translocations required for synaptic potentiation. Thus, altered CDC42 signaling via CDC42EP3 may perturb synaptic plasticity, and contribute to the spine deficits observed in layer 3 pyramidal neurons in schizophrenia. PMID:20385374

  7. Automatic Masking for Robust 3D-2D Image Registration in Image-Guided Spine Surgery

    PubMed Central

    Ketcha, M. D.; De Silva, T.; Uneri, A.; Kleinszig, G.; Vogt, S.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2016-01-01

    During spinal neurosurgery, patient-specific information, planning, and annotation such as vertebral labels can be mapped from preoperative 3D CT to intraoperative 2D radiographs via image-based 3D-2D registration. Such registration has been shown to provide a potentially valuable means of decision support in target localization as well as quality assurance of the surgical product. However, robust registration can be challenged by mismatch in image content between the preoperative CT and intraoperative radiographs, arising, for example, from anatomical deformation or the presence of surgical tools within the radiograph. In this work, we develop and evaluate methods for automatically mitigating the effect of content mismatch by leveraging the surgical planning data to assign greater weight to anatomical regions known to be reliable for registration and vital to the surgical task while removing problematic regions that are highly deformable or often occluded by surgical tools. We investigated two approaches to assigning variable weight (i.e., "masking") to image content and/or the similarity metric: (1) masking the preoperative 3D CT ("volumetric masking"); and (2) masking within the 2D similarity metric calculation ("projection masking"). The accuracy of registration was evaluated in terms of projection distance error (PDE) in 61 cases selected from an IRB-approved clinical study. The best performing of the masking techniques was found to reduce the rate of gross failure (PDE > 20 mm) from 11.48% to 5.57% in this challenging retrospective data set. These approaches provided robustness to content mismatch and eliminated distinct failure modes of registration. Such improvement was gained without additional workflow and has motivated incorporation of the masking methods within a system under development for prospective clinical studies. PMID:27335531

  8. Automatic Masking for Robust 3D-2D Image Registration in Image-Guided Spine Surgery.

    PubMed

    Ketcha, M D; De Silva, T; Uneri, A; Kleinszig, G; Vogt, S; Wolinsky, J-P; Siewerdsen, J H

    During spinal neurosurgery, patient-specific information, planning, and annotation such as vertebral labels can be mapped from preoperative 3D CT to intraoperative 2D radiographs via image-based 3D-2D registration. Such registration has been shown to provide a potentially valuable means of decision support in target localization as well as quality assurance of the surgical product. However, robust registration can be challenged by mismatch in image content between the preoperative CT and intraoperative radiographs, arising, for example, from anatomical deformation or the presence of surgical tools within the radiograph. In this work, we develop and evaluate methods for automatically mitigating the effect of content mismatch by leveraging the surgical planning data to assign greater weight to anatomical regions known to be reliable for registration and vital to the surgical task while removing problematic regions that are highly deformable or often occluded by surgical tools. We investigated two approaches to assigning variable weight (i.e., "masking") to image content and/or the similarity metric: (1) masking the preoperative 3D CT ("volumetric masking"); and (2) masking within the 2D similarity metric calculation ("projection masking"). The accuracy of registration was evaluated in terms of projection distance error (PDE) in 61 cases selected from an IRB-approved clinical study. The best performing of the masking techniques was found to reduce the rate of gross failure (PDE > 20 mm) from 11.48% to 5.57% in this challenging retrospective data set. These approaches provided robustness to content mismatch and eliminated distinct failure modes of registration. Such improvement was gained without additional workflow and has motivated incorporation of the masking methods within a system under development for prospective clinical studies.

  9. Automatic masking for robust 3D-2D image registration in image-guided spine surgery

    NASA Astrophysics Data System (ADS)

    Ketcha, M. D.; De Silva, T.; Uneri, A.; Kleinszig, G.; Vogt, S.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2016-03-01

    During spinal neurosurgery, patient-specific information, planning, and annotation such as vertebral labels can be mapped from preoperative 3D CT to intraoperative 2D radiographs via image-based 3D-2D registration. Such registration has been shown to provide a potentially valuable means of decision support in target localization as well as quality assurance of the surgical product. However, robust registration can be challenged by mismatch in image content between the preoperative CT and intraoperative radiographs, arising, for example, from anatomical deformation or the presence of surgical tools within the radiograph. In this work, we develop and evaluate methods for automatically mitigating the effect of content mismatch by leveraging the surgical planning data to assign greater weight to anatomical regions known to be reliable for registration and vital to the surgical task while removing problematic regions that are highly deformable or often occluded by surgical tools. We investigated two approaches to assigning variable weight (i.e., "masking") to image content and/or the similarity metric: (1) masking the preoperative 3D CT ("volumetric masking"); and (2) masking within the 2D similarity metric calculation ("projection masking"). The accuracy of registration was evaluated in terms of projection distance error (PDE) in 61 cases selected from an IRB-approved clinical study. The best performing of the masking techniques was found to reduce the rate of gross failure (PDE > 20 mm) from 11.48% to 5.57% in this challenging retrospective data set. These approaches provided robustness to content mismatch and eliminated distinct failure modes of registration. Such improvement was gained without additional workflow and has motivated incorporation of the masking methods within a system under development for prospective clinical studies.

  10. BDNF-TrkB controls cocaine-induced dendritic spines in rodent nucleus accumbens dissociated from increases in addictive behaviors.

    PubMed

    Anderson, Ethan M; Wissman, Anne Marie; Chemplanikal, Joyce; Buzin, Nicole; Guzman, Daniel; Larson, Erin B; Neve, Rachael L; Nestler, Eric J; Cowan, Christopher W; Self, David W

    2017-08-29

    Chronic cocaine use is associated with prominent morphological changes in nucleus accumbens shell (NACsh) neurons, including increases in dendritic spine density along with enhanced motivation for cocaine, but a functional relationship between these morphological and behavioral phenomena has not been shown. Here we show that brain-derived neurotrophic factor (BDNF) signaling through tyrosine kinase B (TrkB) receptors in NACsh neurons is necessary for cocaine-induced dendritic spine formation by using either localized TrkB knockout or viral-mediated expression of a dominant negative, kinase-dead TrkB mutant. Interestingly, augmenting wild-type TrkB expression after chronic cocaine self-administration reverses the sustained increase in dendritic spine density, an effect mediated by TrkB signaling pathways that converge on extracellular regulated kinase. Loss of TrkB function after cocaine self-administration, however, leaves spine density intact but markedly enhances the motivation for cocaine, an effect mediated by specific loss of TrkB signaling through phospholipase Cgamma1 (PLCγ1). Conversely, overexpression of PLCγ1 both reduces the motivation for cocaine and reverses dendritic spine density, suggesting a potential target for the treatment of addiction in chronic users. Together, these findings indicate that BDNF-TrkB signaling both mediates and reverses cocaine-induced increases in dendritic spine density in NACsh neurons, and these morphological changes are entirely dissociable from changes in addictive behavior.

  11. The Planar Cell Polarity Transmembrane Protein Vangl2 Promotes Dendrite, Spine and Glutamatergic Synapse Formation in the Mammalian Forebrain

    PubMed Central

    Okerlund, Nathan D.; Stanley, Robert E.; Cheyette, Benjamin N.R.

    2016-01-01

    The transmembrane protein Vangl2, a key regulator of the Wnt/planar cell polarity (PCP) pathway, is involved in dendrite arbor elaboration, dendritic spine formation and glutamatergic synapse formation in mammalian central nervous system neurons. Cultured forebrain neurons from Vangl2 knockout mice have simpler dendrite arbors, fewer total spines, less mature spines and fewer glutamatergic synapse inputs on their dendrites than control neurons. Neurons from mice heterozygous for a semidominant Vangl2 mutation have similar but not identical phenotypes, and these phenotypes are also observed in Golgi-stained brain tissue from adult mutant mice. Given increasing evidence linking psychiatric pathophysiology to these subneuronal sites and structures, our findings underscore the relevance of core PCP proteins including Vangl2 to the underlying biology of major mental illnesses and their treatment. PMID:27606324

  12. The influence of phospho-τ on dendritic spines of cortical pyramidal neurons in patients with Alzheimer's disease.

    PubMed

    Merino-Serrais, Paula; Benavides-Piccione, Ruth; Blazquez-Llorca, Lidia; Kastanauskaite, Asta; Rábano, Alberto; Avila, Jesús; DeFelipe, Javier

    2013-06-01

    The dendritic spines on pyramidal cells represent the main postsynaptic elements of cortical excitatory synapses and they are fundamental structures in memory, learning and cognition. In the present study, we used intracellular injections of Lucifer yellow in fixed tissue to analyse over 19 500 dendritic spines that were completely reconstructed in three dimensions along the length of the basal dendrites of pyramidal neurons in the parahippocampal cortex and CA1 of patients with Alzheimer's disease. Following intracellular injection, sections were immunostained for anti-Lucifer yellow and with tau monoclonal antibodies AT8 and PHF-1, which recognize tau phosphorylated at Ser202/Thr205 and at Ser396/404, respectively. We observed that the diffuse accumulation of phospho-tau in a putative pre-tangle state did not induce changes in the dendrites of pyramidal neurons, whereas the presence of tau aggregates forming intraneuronal neurofibrillary tangles was associated with progressive alteration of dendritic spines (loss of dendritic spines and changes in their morphology) and dendrite atrophy, depending on the degree of tangle development. Thus, the presence of phospho-tau in neurons does not necessarily mean that they suffer severe and irreversible effects as thought previously but rather, the characteristic cognitive impairment in Alzheimer's disease is likely to depend on the relative number of neurons that have well developed tangles.

  13. The influence of phospho-tau on dendritic spines of cortical pyramidal neurons in patients with Alzheimer’s disease

    PubMed Central

    Merino-Serrais, Paula; Benavides-Piccione, Ruth; Blazquez-Llorca, Lidia; Kastanauskaite, Asta; Rábano, Alberto; Avila, Jesús

    2013-01-01

    The dendritic spines on pyramidal cells represent the main postsynaptic elements of cortical excitatory synapses and they are fundamental structures in memory, learning and cognition. In the present study, we used intracellular injections of Lucifer yellow in fixed tissue to analyse over 19 500 dendritic spines that were completely reconstructed in three dimensions along the length of the basal dendrites of pyramidal neurons in the parahippocampal cortex and CA1 of patients with Alzheimer’s disease. Following intracellular injection, sections were immunostained for anti-Lucifer yellow and with tau monoclonal antibodies AT8 and PHF-1, which recognize tau phosphorylated at Ser202/Thr205 and at Ser396/404, respectively. We observed that the diffuse accumulation of phospho-tau in a putative pre-tangle state did not induce changes in the dendrites of pyramidal neurons, whereas the presence of tau aggregates forming intraneuronal neurofibrillary tangles was associated with progressive alteration of dendritic spines (loss of dendritic spines and changes in their morphology) and dendrite atrophy, depending on the degree of tangle development. Thus, the presence of phospho-tau in neurons does not necessarily mean that they suffer severe and irreversible effects as thought previously but rather, the characteristic cognitive impairment in Alzheimer’s disease is likely to depend on the relative number of neurons that have well developed tangles. PMID:23715095

  14. Dopamine depletion of the prefrontal cortex induces dendritic spine loss: reversal by atypical antipsychotic drug treatment.

    PubMed

    Wang, Hui-Dong; Deutch, Ariel Y

    2008-05-01

    Dystrophic changes in dendrites of cortical neurons are present in several neuro-psychiatric disorders, including schizophrenia. The mechanisms that account for dendritic changes in the prefrontal cortex (PFC) in schizophrenia are unclear. Cognitive deficits in schizophrenia have been linked to compromised cortical dopamine function, and the density of the PFC dopamine innervation is decreased in schizophrenia. We determined if 6-hydroxydopamine lesions of the ventral tegmental area that disrupt the PFC dopamine innervation cause dystrophic changes in cortical neurons. Three weeks post-operatively we observed a marked decrease in basal dendritic length and spine density of layer V pyramidal cells in the prelimbic cortex; no change was seen in neurons of the motor cortex. We then examined rats in which the PFC dopamine innervation was lesioned and 3 weeks later were started on chronic treatment with an atypical (olanzapine) or typical (haloperidol) antipsychotic drug. Olanzapine but not haloperidol reversed lesion-induced changes in PFC pyramidal cell dendrites. These data suggest that dopamine regulates dendritic structure in PFC neurons. Moreover, the findings are consistent with a decrease in cortical dopaminergic tone contributing to the pathological changes in the cortex of schizophrenia, and suggest that the progressive cortical loss in schizophrenia may be slowed or reversed by treatment with atypical antipsychotic drugs.

  15. Ankyrin Repeat-rich Membrane Spanning/Kidins220 protein regulates dendritic branching and spine stability in vivo.

    PubMed

    Wu, Synphen H; Arévalo, Juan Carlos; Sarti, Federica; Tessarollo, Lino; Gan, Wen-Biao; Chao, Moses V

    2009-08-01

    The development of nervous system connectivity depends upon the arborization of dendritic fields and the stabilization of dendritic spine synapses. It is well established that neuronal activity and the neurotrophin BDNF modulate these correlated processes. However, the downstream mechanisms by which these extrinsic signals regulate dendritic development and spine stabilization are less well known. Here we report that a substrate of BDNF signaling, the Ankyrin Repeat-rich Membrane Spanning (ARMS) protein or Kidins220, plays a critical role in the branching of cortical and hippocampal dendrites and in the turnover of cortical spines. In the barrel somatosensory cortex and the dentate gyrus, regions where ARMS/Kidins220 is highly expressed, no difference in the complexity of dendritic arbors was observed in 1-month-old adolescent ARMS/Kidins220(+/-) mice compared to wild-type littermates. However, at 3 months of age, young adult ARMS/Kidins220(+/-) mice exhibited decreased dendritic complexity. This suggests that ARMS/Kidins220 does not play a significant role in the initial formation of dendrites but, rather, is involved in the refinement or stabilization of the arbors later in development. In addition, at 1 month of age, the rate of spine elimination was higher in ARMS/Kidins220(+/-) mice than in wild-type mice, suggesting that ARMS/Kidins220(+/-) levels regulate spine stability. Taken together, these data suggest that ARMS/Kidins220 is important for the growth of dendritic arbors and spine stability during an activity- and BDNF-dependent period of development.

  16. 3D dendritic gold nanostructures: seeded growth of a multi-generation fractal architecture.

    PubMed

    Pan, Ming; Xing, Shuangxi; Sun, Ting; Zhou, Wenwen; Sindoro, Melinda; Teo, Hui Hian; Yan, Qingyu; Chen, Hongyu

    2010-10-14

    In this report, we focus on the synthetic challenges for nanoscale 3D fractal architectures, namely the multi-generation growth with control in both size uniformity and colloidal stability; by directing the simultaneous growth of Au and polyaniline on Au seeds, fractal nanoparticles can be achieved with a topology distinctively different from those of spheres, cubes or rods.

  17. Normative 3D opto-electronic stereo-photogrammetric posture and spine morphology data in young healthy adult population.

    PubMed

    D'Amico, Moreno; Kinel, Edyta; Roncoletta, Piero

    2017-01-01

    Observational cross-sectional study. The current study aims to yield normative data: i.e., the physiological standard for 30 selected quantitative 3D parameters that accurately capture and describe a full-skeleton, upright-standing attitude. Specific and exclusive consideration was given to three distinct categories: postural, spine morphology and pelvic parameters. To capture such 3D parameters, the authors selected a non-ionising 3D opto-electronic stereo-photogrammetric approach. This required the identification and measurement of 27 body landmarks, each specifically tagged with a skin marker. As subjects for the measurement of these parameters, a cohort of 124 asymptomatic young adult volunteers was recruited. All parameters were identified and measured within this group. Postural and spine morphology data have been compared between genders. In this regard, only five statistically significant differences were found: pelvis width, pelvis torsion, the "lumbar" lordosis angle value, the lumbar curve length, and the T12-L5 anatomically-bound lumbar angle value. The "thoracic" kyphosis mean angle value was the same in both sexes and, even if, derived from skin markers placed on spinous processes it resulted in perfect agreement with the X-ray based literature. As regards lordosis, a direct comparison was more difficult because methods proposed in the literature differ as to the number and position of vertebrae under consideration, and their related angle values. However, when the L1 superior-L5 inferior end plate Cobb angle was considered, these results aligned strongly with the existing literature. Asymmetry was a standard postural-spinal feature for both sexes. Each subject presented some degree of leg length discrepancy (LLD) with μ = 9.37mm. This was associated with four factors: unbalanced posture and/or underfoot loads, spinal curvature in the frontal plane, and pelvis torsion. This led to the additional study of the effect of LLD equalisation influence on

  18. Normative 3D opto-electronic stereo-photogrammetric posture and spine morphology data in young healthy adult population

    PubMed Central

    2017-01-01

    Design: Observational cross-sectional study. The current study aims to yield normative data: i.e., the physiological standard for 30 selected quantitative 3D parameters that accurately capture and describe a full-skeleton, upright-standing attitude. Specific and exclusive consideration was given to three distinct categories: postural, spine morphology and pelvic parameters. To capture such 3D parameters, the authors selected a non-ionising 3D opto-electronic stereo-photogrammetric approach. This required the identification and measurement of 27 body landmarks, each specifically tagged with a skin marker. As subjects for the measurement of these parameters, a cohort of 124 asymptomatic young adult volunteers was recruited. All parameters were identified and measured within this group. Postural and spine morphology data have been compared between genders. In this regard, only five statistically significant differences were found: pelvis width, pelvis torsion, the “lumbar” lordosis angle value, the lumbar curve length, and the T12-L5 anatomically-bound lumbar angle value. The “thoracic” kyphosis mean angle value was the same in both sexes and, even if, derived from skin markers placed on spinous processes it resulted in perfect agreement with the X-ray based literature. As regards lordosis, a direct comparison was more difficult because methods proposed in the literature differ as to the number and position of vertebrae under consideration, and their related angle values. However, when the L1 superior–L5 inferior end plate Cobb angle was considered, these results aligned strongly with the existing literature. Asymmetry was a standard postural-spinal feature for both sexes. Each subject presented some degree of leg length discrepancy (LLD) with μ = 9.37mm. This was associated with four factors: unbalanced posture and/or underfoot loads, spinal curvature in the frontal plane, and pelvis torsion. This led to the additional study of the effect of LLD

  19. The short-time structural plasticity of dendritic spines is altered in a model of Rett syndrome.

    PubMed

    Landi, Silvia; Putignano, Elena; Boggio, Elena Maria; Giustetto, Maurizio; Pizzorusso, Tommaso; Ratto, Gian Michele

    2011-01-01

    The maturation of excitatory transmission comes about through a developmental period in which dendritic spines are highly motile and their number, form and size are rapidly changing. Surprisingly, although these processes are crucial for the formation of cortical circuitry, little is known about possible alterations of these processes in brain disease. By means of acute in vivo 2-photon imaging we show that the dynamic properties of dendritic spines of layer V cortical neurons are deeply affected in a mouse model of Rett syndrome (RTT) at a time around P25 when the neuronal phenotype of the disease is still mild. Then, we show that 24h after a subcutaneous injection of IGF-1 spine dynamics is restored. Our study demonstrates that spine dynamics in RTT mice is severely impaired early during development and suggest that treatments for RTT should be started very early in order to reestablish a normal period of spine plasticity.

  20. The internal architecture of dendritic spines revealed by super-resolution imaging: What did we learn so far?

    SciTech Connect

    MacGillavry, Harold D. Hoogenraad, Casper C.

    2015-07-15

    The molecular architecture of dendritic spines defines the efficiency of signal transmission across excitatory synapses. It is therefore critical to understand the mechanisms that control the dynamic localization of the molecular constituents within spines. However, because of the small scale at which most processes within spines take place, conventional light microscopy techniques are not adequate to provide the necessary level of resolution. Recently, super-resolution imaging techniques have overcome the classical barrier imposed by the diffraction of light, and can now resolve the localization and dynamic behavior of proteins within small compartments with nanometer precision, revolutionizing the study of dendritic spine architecture. Here, we highlight exciting new findings from recent super-resolution studies on neuronal spines, and discuss how these studies revealed important new insights into how protein complexes are assembled and how their dynamic behavior shapes the efficiency of synaptic transmission.

  1. Neuronal Actin Dynamics, Spine Density and Neuronal Dendritic Complexity Are Regulated by CAP2.

    PubMed

    Kumar, Atul; Paeger, Lars; Kosmas, Kosmas; Kloppenburg, Peter; Noegel, Angelika A; Peche, Vivek S

    2016-01-01

    Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2(gt/gt) mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2(gt/gt) with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2(gt/gt) neurons. Moreover, reduced surface GluA1 was observed in mutant neurons under basal condition and after induction of chemical LTP. Additionally, we show an interaction between CAP2 and n-cofilin, presumably mediated through the C-terminal domain of CAP2 and dependent on cofilin Ser3 phosphorylation. In vivo, the consequences of this interaction were altered phosphorylated cofilin levels and formation of cofilin aggregates in the neurons. Thus, our studies identify a novel role of CAP2 in neuronal development and neuronal actin dynamics.

  2. Neuronal Actin Dynamics, Spine Density and Neuronal Dendritic Complexity Are Regulated by CAP2

    PubMed Central

    Kumar, Atul; Paeger, Lars; Kosmas, Kosmas; Kloppenburg, Peter; Noegel, Angelika A.; Peche, Vivek S.

    2016-01-01

    Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2gt/gt mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2gt/gt with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2gt/gt neurons. Moreover, reduced surface GluA1 was observed in mutant neurons under basal condition and after induction of chemical LTP. Additionally, we show an interaction between CAP2 and n-cofilin, presumably mediated through the C-terminal domain of CAP2 and dependent on cofilin Ser3 phosphorylation. In vivo, the consequences of this interaction were altered phosphorylated cofilin levels and formation of cofilin aggregates in the neurons. Thus, our studies identify a novel role of CAP2 in neuronal development and neuronal actin dynamics. PMID:27507934

  3. Paternal deprivation during infancy results in dendrite- and time-specific changes of dendritic development and spine formation in the orbitofrontal cortex of the biparental rodent Octodon degus.

    PubMed

    Helmeke, C; Seidel, K; Poeggel, G; Bredy, T W; Abraham, A; Braun, K

    2009-10-20

    The aim of this study in the biparental rodent Octodon degus was to assess the impact of paternal deprivation on neuronal and synaptic development in the orbitofrontal cortex, a prefrontal region which is essential for emotional and cognitive function. On the behavioral level the quantitative comparison of parental behaviors in biparental and single-mother families revealed that (i) degu fathers significantly participate in parental care and (ii) single-mothers do not increase their maternal care to compensate the lack of paternal care. On the brain structural level we show in three-week-old father-deprived animals that layer II/III pyramidal neurons in the orbitofrontal cortex displayed significantly lower spine densities on apical and basal dendrites. Whereas biparentally raised animals have reached adult spine density values at postnatal day 21, fatherless animals seem "to catch up" by a delayed increase of spine density until reaching similar values as biparentally raised animals in adulthood. However, in adulthood reduced apical spine numbers together with shorter apical dendrites were observed in father-deprived animals, which indicates that dendritic growth and synapse formation (seen in biparental animals between postnatal day 21 and adulthood) were significantly suppressed. These results demonstrate that paternal deprivation delays and partly suppresses the development of orbitofrontal circuits. The retarded dendritic and synaptic development of the apical dendrites of layer II/III pyramidal neurons in the orbitofrontal cortex of adult fatherless animals may reflect a reduced excitatory connectivity of this cortical subregion.

  4. KCC2 regulates actin dynamics in dendritic spines via interaction with β-PIX.

    PubMed

    Llano, Olaya; Smirnov, Sergey; Soni, Shetal; Golubtsov, Andrey; Guillemin, Isabelle; Hotulainen, Pirta; Medina, Igor; Nothwang, Hans Gerd; Rivera, Claudio; Ludwig, Anastasia

    2015-06-08

    Chloride extrusion in mature neurons is largely mediated by the neuron-specific potassium-chloride cotransporter KCC2. In addition, independently of its chloride transport function, KCC2 regulates the development and morphology of dendritic spines through structural interactions with the actin cytoskeleton. The mechanism of this effect remains largely unknown. In this paper, we show a novel pathway for KCC2-mediated regulation of the actin cytoskeleton in neurons. We found that KCC2, through interaction with the b isoform of Rac/Cdc42 guanine nucleotide exchange factor β-PIX, regulates the activity of Rac1 GTPase and the phosphorylation of one of the major actin-regulating proteins, cofilin-1. KCC2-deficient neurons had abnormally high levels of phosphorylated cofilin-1. Consistently, dendritic spines of these neurons exhibited a large pool of stable actin, resulting in reduced spine motility and diminished density of functional synapses. In conclusion, we describe a novel signaling pathway that couples KCC2 to the cytoskeleton and regulates the formation of glutamatergic synapses. © 2015 Llano et al.

  5. KCC2 regulates actin dynamics in dendritic spines via interaction with β-PIX

    PubMed Central

    Llano, Olaya; Smirnov, Sergey; Soni, Shetal; Golubtsov, Andrey; Guillemin, Isabelle; Hotulainen, Pirta; Medina, Igor; Nothwang, Hans Gerd

    2015-01-01

    Chloride extrusion in mature neurons is largely mediated by the neuron-specific potassium-chloride cotransporter KCC2. In addition, independently of its chloride transport function, KCC2 regulates the development and morphology of dendritic spines through structural interactions with the actin cytoskeleton. The mechanism of this effect remains largely unknown. In this paper, we show a novel pathway for KCC2-mediated regulation of the actin cytoskeleton in neurons. We found that KCC2, through interaction with the b isoform of Rac/Cdc42 guanine nucleotide exchange factor β-PIX, regulates the activity of Rac1 GTPase and the phosphorylation of one of the major actin-regulating proteins, cofilin-1. KCC2-deficient neurons had abnormally high levels of phosphorylated cofilin-1. Consistently, dendritic spines of these neurons exhibited a large pool of stable actin, resulting in reduced spine motility and diminished density of functional synapses. In conclusion, we describe a novel signaling pathway that couples KCC2 to the cytoskeleton and regulates the formation of glutamatergic synapses. PMID:26056138

  6. Dysbindin-1, WAVE2 and Abi-1 form a complex that regulates dendritic spine formation.

    PubMed

    Ito, H; Morishita, R; Shinoda, T; Iwamoto, I; Sudo, K; Okamoto, K; Nagata, K

    2010-10-01

    Genetic variations in dysbindin-1 (dystrobrevin-binding protein-1) are one of the most commonly reported variations associated with schizophrenia. As schizophrenia could be regarded as a neurodevelopmental disorder resulting from abnormalities of synaptic connectivity, we attempted to clarify the function of dysbindin-1 in neuronal development. We examined the developmental change of dysbindin-1 in rat brain by western blotting and found that a 50 kDa isoform is highly expressed during the embryonic stage, whereas a 40 kDa one is detected at postnatal day 11 and increased thereafter. Immunofluorescent analyses revealed that dysbindin-1 is enriched at the spine-like structure of primary cultured rat hippocampal neurons. We identified WAVE2, but not N-WASP, as a binding partner for dysbindin-1. We also found that Abi-1, a binding molecule for WAVE2 involved in spine morphogenesis, interacts with dysbindin-1. Although dysbindin-1, WAVE2 and Abi-1 form a ternary complex, dysbindin-1 promoted the binding of WAVE2 to Abi-1. RNA interference-mediated knockdown of dysbindin-1 led to the generation of abnormally elongated immature dendritic protrusions. The present results indicate possible functions of dysbindin-1 at the postsynapse in the regulation of dendritic spine morphogenesis through the interaction with WAVE2 and Abi-1.

  7. Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy.

    PubMed

    Höhn, K; Fuchs, J; Fröber, A; Kirmse, R; Glass, B; Anders-Össwein, M; Walther, P; Kräusslich, H-G; Dietrich, C

    2015-08-01

    In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV-pulsed mature human dendritic cells. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  8. Reduced density of dendritic spines in pyramidal neurons of rats exposed to alcohol during early postnatal life.

    PubMed

    De Giorgio, Andrea; Granato, Alberto

    2015-04-01

    Dendritic spines are the main postsynaptic sites of excitatory connections of neocortical pyramidal neurons. Alterations of spine shape, number, and density can be observed in different mental diseases, including those caused by developmental alcohol exposure. Pyramidal neurons of layer 2/3 are the most abundant cells of the neocortex and represent the main source of associative cortico-cortical connections. These neurons are essential for higher functions mediated by the cortex such as feature selection and perceptual grouping. Furthermore, their connections have been shown to be altered in experimental models of fetal alcohol spectrum disorders. Here, we used a Golgi-like tracing method to study the spine density of layer 2/3 associative pyramidal neurons in the somatosensory cortex of adult rats exposed to alcohol during the first postnatal week. The main result of the present study is represented by the decreased spine density in the apical dendrite of alcohol-treated rats, as compared to controls. As to the basal dendritic tree, there were no significant differences between the experimental and the control group. A decreased density of dendritic spines in the apical dendrite may impair the excitatory input onto pyramidal neurons, thus resulting in a widespread alteration of the cortical information flow.

  9. The Role of Posttraumatic Hypothermia in Preventing Dendrite Degeneration and Spine Loss after Severe Traumatic Brain Injury

    PubMed Central

    Wang, Chuan-fang; Zhao, Cheng-cheng; Jiang, Gan; Gu, Xiao; Feng, Jun-feng; Jiang, Ji-yao

    2016-01-01

    Posttraumatic hypothermia prevents cell death and promotes functional outcomes after traumatic brain injury (TBI). However, little is known regarding the effect of hypothermia on dendrite degeneration and spine loss after severe TBI. In the present study, we used thy1-GFP transgenic mice to investigate the effect of hypothermia on the dendrites and spines in layer V/VI of the ipsilateral cortex after severe TBI. We found that hypothermia (33 °C) dramatically prevented dendrite degeneration and spine loss 1 and 7 days after CCI. The Morris water maze test revealed that hypothermia preserved the learning and memory functions of mice after CCI. Hypothermia significantly increased the expression of the synaptic proteins GluR1 and PSD-95 at 1 and 7 days after CCI in the ipsilateral cortex and hippocampus compared with that of the normothermia TBI group. Hypothermia also increased cortical and hippocampal BDNF levels. These results suggest that posttraumatic hypothermia is an effective method to prevent dendrite degeneration and spine loss and preserve learning and memory function after severe TBI. Increasing cortical and hippocampal BDNF levels might be the mechanism through which hypothermia prevents dendrite degeneration and spine loss and preserves learning and memory function. PMID:27833158

  10. Fragile X-like behaviors and abnormal cortical dendritic spines in cytoplasmic FMR1-interacting protein 2-mutant mice.

    PubMed

    Han, Kihoon; Chen, Hogmei; Gennarino, Vincenzo A; Richman, Ronald; Lu, Hui-Chen; Zoghbi, Huda Y

    2015-04-01

    Silencing of fragile X mental retardation 1 (FMR1) gene and loss of fragile X mental retardation protein (FMRP) cause fragile X syndrome (FXS), a genetic disorder characterized by intellectual disability and autistic behaviors. FMRP is an mRNA-binding protein regulating neuronal translation of target mRNAs. Abnormalities in actin-rich dendritic spines are major neuronal features in FXS, but the molecular mechanism and identity of FMRP targets mediating this phenotype remain largely unknown. Cytoplasmic FMR1-interacting protein 2 (Cyfip2) was identified as an interactor of FMRP, and its mRNA is a highly ranked FMRP target in mouse brain. Importantly, Cyfip2 is a component of WAVE regulatory complex, a key regulator of actin cytoskeleton, suggesting that Cyfip2 could be implicated in the dendritic spine phenotype of FXS. Here, we generated and characterized Cyfip2-mutant (Cyfip2(+/-)) mice. We found that Cyfip2(+/-) mice exhibited behavioral phenotypes similar to Fmr1-null (Fmr1(-/y)) mice, an animal model of FXS. Synaptic plasticity and dendritic spines were normal in Cyfip2(+/-) hippocampus. However, dendritic spines were altered in Cyfip2(+/-) cortex, and the dendritic spine phenotype of Fmr1(-/y) cortex was aggravated in Fmr1(-/y); Cyfip2(+/-) double-mutant mice. In addition to the spine changes at basal state, metabotropic glutamate receptor (mGluR)-induced dendritic spine regulation was impaired in both Fmr1(-/y) and Cyfip2(+/-) cortical neurons. Mechanistically, mGluR activation induced mRNA translation-dependent increase of Cyfip2 in wild-type cortical neurons, but not in Fmr1(-/y) or Cyfip2(+/-) neurons. These results suggest that misregulation of Cyfip2 function and its mGluR-induced expression contribute to the neurobehavioral phenotypes of FXS.

  11. Dendritic BDNF synthesis is required for late-phase spine maturation and recovery of cortical responses following sensory deprivation.

    PubMed

    Kaneko, Megumi; Xie, Yuxiang; An, Juan Ji; Stryker, Michael P; Xu, Baoji

    2012-04-04

    Sensory experience in early postnatal life shapes neuronal connections in the brain. Here we report that the local synthesis of brain-derived neurotrophic factor (BDNF) in dendrites plays an important role in this process. We found that dendritic spines of layer 2/3 pyramidal neurons of the visual cortex in mutant mice lacking dendritic Bdnf mRNA and thus local BDNF synthesis were normal at 3 weeks of age, but thinner, longer, and more closely spaced (morphological features of immaturity) at 4 months of age than in wild-type (WT) littermates. Layer 2/3 of the visual cortex in these mutant animals also had fewer GABAergic presynaptic terminals at both ages. The overall size and shape of dendritic arbors were, however, similar in mutant and WT mice at both ages. By using optical imaging of intrinsic signals and single-unit recordings, we found that mutant animals failed to recover cortical responsiveness following monocular deprivation (MD) during the critical period, although they displayed normally the competitive loss of responsiveness to an eye briefly deprived of vision. Furthermore, MD still induced a loss of responsiveness to the closed eye in adult mutant mice, but not in adult WT mice. These results indicate that dendritic BDNF synthesis is required for spine pruning, late-phase spine maturation, and recovery of cortical responsiveness following sensory deprivation. They also suggest that maturation of dendritic spines is required for the maintenance of cortical responsiveness following sensory deprivation in adulthood.

  12. Intraoperative evaluation of device placement in spine surgery using known-component 3D-2D image registration

    NASA Astrophysics Data System (ADS)

    Uneri, A.; De Silva, T.; Goerres, J.; Jacobson, M. W.; Ketcha, M. D.; Reaungamornrat, S.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Osgood, G. M.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2017-04-01

    Intraoperative x-ray radiography/fluoroscopy is commonly used to assess the placement of surgical devices in the operating room (e.g. spine pedicle screws), but qualitative interpretation can fail to reliably detect suboptimal delivery and/or breach of adjacent critical structures. We present a 3D-2D image registration method wherein intraoperative radiographs are leveraged in combination with prior knowledge of the patient and surgical components for quantitative assessment of device placement and more rigorous quality assurance (QA) of the surgical product. The algorithm is based on known-component registration (KC-Reg) in which patient-specific preoperative CT and parametric component models are used. The registration performs optimization of gradient similarity, removes the need for offline geometric calibration of the C-arm, and simultaneously solves for multiple component bodies, thereby allowing QA in a single step (e.g. spinal construct with 4-20 screws). Performance was tested in a spine phantom, and first clinical results are reported for QA of transpedicle screws delivered in a patient undergoing thoracolumbar spine surgery. Simultaneous registration of ten pedicle screws (five contralateral pairs) demonstrated mean target registration error (TRE) of 1.1  ±  0.1 mm at the screw tip and 0.7  ±  0.4° in angulation when a prior geometric calibration was used. The calibration-free formulation, with the aid of component collision constraints, achieved TRE of 1.4  ±  0.6 mm. In all cases, a statistically significant improvement (p  <  0.05) was observed for the simultaneous solutions in comparison to previously reported sequential solution of individual components. Initial application in clinical data in spine surgery demonstrated TRE of 2.7  ±  2.6 mm and 1.5  ±  0.8°. The KC-Reg algorithm offers an independent check and quantitative QA of the surgical product using radiographic/fluoroscopic views

  13. Intraoperative evaluation of device placement in spine surgery using known-component 3D-2D image registration.

    PubMed

    Uneri, A; De Silva, T; Goerres, J; Jacobson, M W; Ketcha, M D; Reaungamornrat, S; Kleinszig, G; Vogt, S; Khanna, A J; Osgood, G M; Wolinsky, J-P; Siewerdsen, J H

    2017-04-21

    Intraoperative x-ray radiography/fluoroscopy is commonly used to assess the placement of surgical devices in the operating room (e.g. spine pedicle screws), but qualitative interpretation can fail to reliably detect suboptimal delivery and/or breach of adjacent critical structures. We present a 3D-2D image registration method wherein intraoperative radiographs are leveraged in combination with prior knowledge of the patient and surgical components for quantitative assessment of device placement and more rigorous quality assurance (QA) of the surgical product. The algorithm is based on known-component registration (KC-Reg) in which patient-specific preoperative CT and parametric component models are used. The registration performs optimization of gradient similarity, removes the need for offline geometric calibration of the C-arm, and simultaneously solves for multiple component bodies, thereby allowing QA in a single step (e.g. spinal construct with 4-20 screws). Performance was tested in a spine phantom, and first clinical results are reported for QA of transpedicle screws delivered in a patient undergoing thoracolumbar spine surgery. Simultaneous registration of ten pedicle screws (five contralateral pairs) demonstrated mean target registration error (TRE) of 1.1  ±  0.1 mm at the screw tip and 0.7  ±  0.4° in angulation when a prior geometric calibration was used. The calibration-free formulation, with the aid of component collision constraints, achieved TRE of 1.4  ±  0.6 mm. In all cases, a statistically significant improvement (p  <  0.05) was observed for the simultaneous solutions in comparison to previously reported sequential solution of individual components. Initial application in clinical data in spine surgery demonstrated TRE of 2.7  ±  2.6 mm and 1.5  ±  0.8°. The KC-Reg algorithm offers an independent check and quantitative QA of the surgical product using radiographic/fluoroscopic views

  14. Correlated memory defects and hippocampal dendritic spine loss after acute stress involve corticotropin-releasing hormone signaling.

    PubMed

    Chen, Yuncai; Rex, Christopher S; Rice, Courtney J; Dubé, Céline M; Gall, Christine M; Lynch, Gary; Baram, Tallie Z

    2010-07-20

    Stress affects the hippocampus, a brain region crucial for memory. In rodents, acute stress may reduce density of dendritic spines, the location of postsynaptic elements of excitatory synapses, and impair long-term potentiation and memory. Steroid stress hormones and neurotransmitters have been implicated in the underlying mechanisms, but the role of corticotropin-releasing hormone (CRH), a hypothalamic hormone also released during stress within hippocampus, has not been elucidated. In addition, the causal relationship of spine loss and memory defects after acute stress is unclear. We used transgenic mice that expressed YFP in hippocampal neurons and found that a 5-h stress resulted in profound loss of learning and memory. This deficit was associated with selective disruption of long-term potentiation and of dendritic spine integrity in commissural/associational pathways of hippocampal area CA3. The degree of memory deficit in individual mice correlated significantly with the reduced density of area CA3 apical dendritic spines in the same mice. Moreover, administration of the CRH receptor type 1 (CRFR(1)) blocker NBI 30775 directly into the brain prevented the stress-induced spine loss and restored the stress-impaired cognitive functions. We conclude that acute, hours-long stress impairs learning and memory via mechanisms that disrupt the integrity of hippocampal dendritic spines. In addition, establishing the contribution of hippocampal CRH-CRFR(1) signaling to these processes highlights the complexity of the orchestrated mechanisms by which stress impacts hippocampal structure and function.

  15. Multi-stage 3D-2D registration for correction of anatomical deformation in image-guided spine surgery

    NASA Astrophysics Data System (ADS)

    Ketcha, M. D.; De Silva, T.; Uneri, A.; Jacobson, M. W.; Goerres, J.; Kleinszig, G.; Vogt, S.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2017-06-01

    A multi-stage image-based 3D-2D registration method is presented that maps annotations in a 3D image (e.g. point labels annotating individual vertebrae in preoperative CT) to an intraoperative radiograph in which the patient has undergone non-rigid anatomical deformation due to changes in patient positioning or due to the intervention itself. The proposed method (termed msLevelCheck) extends a previous rigid registration solution (LevelCheck) to provide an accurate mapping of vertebral labels in the presence of spinal deformation. The method employs a multi-stage series of rigid 3D-2D registrations performed on sets of automatically determined and increasingly localized sub-images, with the final stage achieving a rigid mapping for each label to yield a locally rigid yet globally deformable solution. The method was evaluated first in a phantom study in which a CT image of the spine was acquired followed by a series of 7 mobile radiographs with increasing degree of deformation applied. Second, the method was validated using a clinical data set of patients exhibiting strong spinal deformation during thoracolumbar spine surgery. Registration accuracy was assessed using projection distance error (PDE) and failure rate (PDE  >  20 mm—i.e. label registered outside vertebra). The msLevelCheck method was able to register all vertebrae accurately for all cases of deformation in the phantom study, improving the maximum PDE of the rigid method from 22.4 mm to 3.9 mm. The clinical study demonstrated the feasibility of the approach in real patient data by accurately registering all vertebral labels in each case, eliminating all instances of failure encountered in the conventional rigid method. The multi-stage approach demonstrated accurate mapping of vertebral labels in the presence of strong spinal deformation. The msLevelCheck method maintains other advantageous aspects of the original LevelCheck method (e.g. compatibility with standard clinical workflow, large

  16. Centella asiatica attenuates Aβ-induced neurodegenerative spine loss and dendritic simplification.

    PubMed

    Gray, Nora E; Zweig, Jonathan A; Murchison, Charles; Caruso, Maya; Matthews, Donald G; Kawamoto, Colleen; Harris, Christopher J; Quinn, Joseph F; Soumyanath, Amala

    2017-04-12

    The medicinal plant Centella asiatica has long been used to improve memory and cognitive function. We have previously shown that a water extract from the plant (CAW) is neuroprotective against the deleterious cognitive effects of amyloid-β (Aβ) exposure in a mouse model of Alzheimer's disease, and improves learning and memory in healthy aged mice as well. This study explores the physiological underpinnings of those effects by examining how CAW, as well as chemical compounds found within the extract, modulate synaptic health in Aβ-exposed neurons. Hippocampal neurons from amyloid precursor protein over-expressing Tg2576 mice and their wild-type (WT) littermates were used to investigate the effect of CAW and various compounds found within the extract on Aβ-induced dendritic simplification and synaptic loss. CAW enhanced arborization and spine densities in WT neurons and prevented the diminished outgrowth of dendrites and loss of spines caused by Aβ exposure in Tg2576 neurons. Triterpene compounds present in CAW were found to similarly improve arborization although they did not affect spine density. In contrast caffeoylquinic acid (CQA) compounds from CAW were able to modulate both of these endpoints, although there was specificity as to which CQAs mediated which effect. These data suggest that CAW, and several of the compounds found therein, can improve dendritic arborization and synaptic differentiation in the context of Aβ exposure which may underlie the cognitive improvement observed in response to the extract in vivo. Additionally, since CAW, and its constituent compounds, also improved these endpoints in WT neurons, these results may point to a broader therapeutic utility of the extract beyond Alzheimer's disease.

  17. Voluntary exercise and caloric restriction enhance hippocampal dendritic spine density and BDNF levels in diabetic mice.

    PubMed

    Stranahan, Alexis M; Lee, Kim; Martin, Bronwen; Maudsley, Stuart; Golden, Erin; Cutler, Roy G; Mattson, Mark P

    2009-10-01

    Diabetes may adversely affect cognitive function, but the underlying mechanisms are unknown. To investigate whether manipulations that enhance neurotrophin levels will also restore neuronal structure and function in diabetes, we examined the effects of wheel running and dietary energy restriction on hippocampal neuron morphology and brain-derived neurotrophic factor (BDNF) levels in db/db mice, a model of insulin resistant diabetes. Running wheel activity, caloric restriction, or the combination of the two treatments increased levels of BDNF in the hippocampus of db/db mice. Enhancement of hippocampal BDNF was accompanied by increases in dendritic spine density on the secondary and tertiary dendrites of dentate granule neurons. These studies suggest that diabetes exerts detrimental effects on hippocampal structure, and that this state can be attenuated by increasing energy expenditure and decreasing energy intake.

  18. Sexual behavior and dendritic spine density of posterodorsal medial amygdala neurons in oxytocin knockout female mice.

    PubMed

    Becker, Roberta Oriques; Lazzari, Virgínia Meneghini; Menezes, Itiana Castro; Morris, Mariana; Rigatto, Katya; Lucion, Aldo B; Rasia-Filho, Alberto A; Giovenardi, Márcia

    2013-11-01

    Central oxytocin (OT) and arginine-vasopressin (AVP) have been shown to play an important role in sexual behavior and neuroendocrine secretion in rodents. The results of exogenous OT administration on sexual behaviors in male and female mice are controversial. This study aimed to analyze the role of OT in sexual behavior, the number of oocytes and the density of dendritic spines in the posterodorsal medial amygdala (MePD) of female mice with selective deletion of the OT gene (OTKO). Female C57BL/6 mice were genotyped and divided into control (WT) and OTKO groups (n=11 each). All experiments were performed in the proestrus phase. Compared to WT data, our results showed that the OTKO group had a significant increase in the latency for the display of lordosis behavior (490.8 ± 113.8 and 841.9 ± 53.9, respectively) and a decrease in both the frequency (6.3 ± 2.4 and 0.5 ± 0.4) and duration (49.3 ± 19.9 and 7.2 ± 7.1) of lordosis and a reduction in the number of oocytes (12.2 ± 0.8 and 9.9 ± 0.6). However, the OTKO group showed a higher density of proximal dendritic spines in the MePD compared to the WT group (2.4 ± 0.1 and 1.9 ± 0.1 spines/dendritic μm, respectively). No significant difference was observed in the plasma levels of AVP between the groups (OTKO: 617.1 ± 96.0 and WT: 583.3 ± 112.0 pg/mL). Our data suggest that OT plays a crucial role in the sexual behavior display, number of released oocytes and density of dendritic spines in the MePD of female mice. The AVP plasma concentration was not affected in the OTKO animals. Copyright © 2013. Published by Elsevier B.V.

  19. Rapid, transient potentiation of dendritic spines in context-induced relapse to cocaine seeking.

    PubMed

    Stankeviciute, Neringa M; Scofield, Michael D; Kalivas, Peter W; Gipson, Cassandra D

    2014-11-01

    Addiction to cocaine produces long-lasting, stable changes in brain synaptic physiology that might contribute to the vulnerability to relapse. In humans, exposure to environmental contexts previously paired with drug use precipitates relapse, but the neurobiological mechanisms mediating this process are unknown. Initiation of cocaine relapse via re-exposure to a drug-associated context elicited reinstatement of cocaine seeking as well as rapid, transient synaptic plasticity in the nucleus accumbens core (NAcore), measured as an increase in dendritic spine diameter. These results show that rapid context-evoked synaptic potentiation in the NAcore may underpin relapse to cocaine use. © 2013 Society for the Study of Addiction.

  20. Simultaneous analysis of dendritic spine density, morphology and excitatory glutamate receptors during neuron maturation in vitro by quantitative immunocytochemistry.

    PubMed

    Nwabuisi-Heath, Evelyn; LaDu, Mary Jo; Yu, Chunjiang

    2012-06-15

    Alterations in the density and morphology of dendritic spines are characteristic of multiple cognitive disorders. Elucidating the molecular mechanisms underlying spine alterations are facilitated by the use of experimental and analytical methods that permit concurrent evaluation of changes in spine density, morphology and composition. Here, an automated and quantitative immunocytochemical method for the simultaneous analysis of changes in the density and morphology of spines and excitatory glutamate receptors was established to analyze neuron maturation, in vitro. In neurons of long-term neuron-glia co-cultures, spine density as measured by drebrin cluster fluorescence, increased from DIV (days in vitro)10 to DIV18 (formation phase), remained stable from DIV18 to DIV21 (maintenance phase), and decreased from DIV21 to DIV26 (loss phase). The densities of spine-localized NMDAR and AMPAR clusters followed a similar trend. Spine head sizes as measured by the fluorescence intensities of drebrin clusters increased from DIV10 to DIV21 and decreased from DIV21 to DIV26. Changes in the densities of NR1-only, GluR2-only, and NR1+GluR2 spines were measured by the colocalizations of NR1 and GluR2 clusters with drebrin clusters. The densities of NR1-only spines remained stable from the maintenance to the loss phases, while GluR2-only and NR1+GluR2 spines decreased during the loss phase, thus suggesting GluR2 loss as a proximal molecular event that may underlie spine alterations during neuron maturation. This study demonstrates a sensitive and quantitative immunocytochemical method for the concurrent analysis of changes in spine density, morphology and composition, a valuable tool for determining molecular events involved in dendritic spine alterations. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Alterations to dendritic spine morphology, but not dendrite patterning, of cortical projection neurons in Tc1 and Ts1Rhr mouse models of Down syndrome.

    PubMed

    Haas, Matilda A; Bell, Donald; Slender, Amy; Lana-Elola, Eva; Watson-Scales, Sheona; Fisher, Elizabeth M C; Tybulewicz, Victor L J; Guillemot, François

    2013-01-01

    Down Syndrome (DS) is a highly prevalent developmental disorder, affecting 1/700 births. Intellectual disability, which affects learning and memory, is present in all cases and is reflected by below average IQ. We sought to determine whether defective morphology and connectivity in neurons of the cerebral cortex may underlie the cognitive deficits that have been described in two mouse models of DS, the Tc1 and Ts1Rhr mouse lines. We utilised in utero electroporation to label a cohort of future upper layer projection neurons in the cerebral cortex of developing mouse embryos with GFP, and then examined neuronal positioning and morphology in early adulthood, which revealed no alterations in cortical layer position or morphology in either Tc1 or Ts1Rhr mouse cortex. The number of dendrites, as well as dendrite length and branching was normal in both DS models, compared with wildtype controls. The sites of projection neuron synaptic inputs, dendritic spines, were analysed in Tc1 and Ts1Rhr cortex at three weeks and three months after birth, and significant changes in spine morphology were observed in both mouse lines. Ts1Rhr mice had significantly fewer thin spines at three weeks of age. At three months of age Tc1 mice had significantly fewer mushroom spines--the morphology associated with established synaptic inputs and learning and memory. The decrease in mushroom spines was accompanied by a significant increase in the number of stubby spines. This data suggests that dendritic spine abnormalities may be a more important contributor to cognitive deficits in DS models, rather than overall neuronal architecture defects.

  2. Alterations to Dendritic Spine Morphology, but Not Dendrite Patterning, of Cortical Projection Neurons in Tc1 and Ts1Rhr Mouse Models of Down Syndrome

    PubMed Central

    Haas, Matilda A.; Bell, Donald; Slender, Amy; Lana-Elola, Eva; Watson-Scales, Sheona; Fisher, Elizabeth M. C.; Tybulewicz, Victor L. J.; Guillemot, François

    2013-01-01

    Down Syndrome (DS) is a highly prevalent developmental disorder, affecting 1/700 births. Intellectual disability, which affects learning and memory, is present in all cases and is reflected by below average IQ. We sought to determine whether defective morphology and connectivity in neurons of the cerebral cortex may underlie the cognitive deficits that have been described in two mouse models of DS, the Tc1 and Ts1Rhr mouse lines. We utilised in utero electroporation to label a cohort of future upper layer projection neurons in the cerebral cortex of developing mouse embryos with GFP, and then examined neuronal positioning and morphology in early adulthood, which revealed no alterations in cortical layer position or morphology in either Tc1 or Ts1Rhr mouse cortex. The number of dendrites, as well as dendrite length and branching was normal in both DS models, compared with wildtype controls. The sites of projection neuron synaptic inputs, dendritic spines, were analysed in Tc1 and Ts1Rhr cortex at three weeks and three months after birth, and significant changes in spine morphology were observed in both mouse lines. Ts1Rhr mice had significantly fewer thin spines at three weeks of age. At three months of age Tc1 mice had significantly fewer mushroom spines - the morphology associated with established synaptic inputs and learning and memory. The decrease in mushroom spines was accompanied by a significant increase in the number of stubby spines. This data suggests that dendritic spine abnormalities may be a more important contributor to cognitive deficits in DS models, rather than overall neuronal architecture defects. PMID:24205261

  3. A Golgi study of the plasticity of dendritic spines in the hypothalamic ventromedial nucleus during the estrous cycle of female rats.

    PubMed

    González-Burgos, I; Velázquez-Zamora, D A; González-Tapia, D; Cervantes, M

    2015-07-09

    Estradiol-induced plasticity involves changes in dendritic spine density and in the relative proportions of the different dendritic spine types that influence neurons and neural circuits. Such events affect brain structures that control the timing of neuroendocrine and behavioral processes, influencing both reproductive and cognitive functions during the estrous cycle. Accordingly, to investigate the dendritic spine-related plastic changes that may affect the neural processes involved in mating, estradiol-mediated dendritic spine plasticity was studied in type II cells situated in the ventrolateral portion of the ventromedial hypothalamic nucleus (VMN) of female, adult rats. The rats were assigned to four different groups (n=6) in function of their stage in the estrous cycle: proestrus, estrus, metaestrus, and diestrus. Dendritic spine density and the proportions of the different spine types on type II neurons were analyzed in the ventrolateral region of the VMN of these animals. Dendritic spine density on primary dendrites of VMN type II neurons was significantly lower in metaestrus than in diestrus, proestrus and estrus (with no differences between these latter stages). However, a significant variation in the proportional density of the different spine types was found, with a higher proportion of thin spines in diestrus, proestrus and estrus than in metaestrus. Likewise, a higher proportion of mushroom spines was seen in diestrus and proestrus than in metaestrus, and a higher proportion of stubby spines in estrus than in diestrus and metaestrus. Very few branched spines were found during proestrus and they were not detected during estrus or metaestrus. The different types of dendritic spines in non-projection neurons of the VMN could serve to maintain greater synaptic excitatory activity when receptivity and estradiol levels are maximal. However, they may also fulfill an additional functional role when receptivity and estradiol decline. To date specific roles of

  4. Global and regional kinematics of the cervical spine during upper cervical spine manipulation: a reliability analysis of 3D motion data.

    PubMed

    Dugailly, Pierre-Michel; Beyer, Benoît; Sobczak, Stéphane; Salvia, Patrick; Feipel, Véronique

    2014-10-01

    Studies reporting spine kinematics during cervical manipulation are usually related to continuous global head-trunk motion or discrete angular displacements for pre-positioning. To date, segmental data analyzing continuous kinematics of cervical manipulation is lacking. The objective of this study was to investigate upper cervical spine (UCS) manipulation in vitro. This paper reports an inter- and intra-rater reliability analysis of kinematics during high velocity low amplitude manipulation of the UCS. Integration of kinematics into specific-subject 3D models has been processed as well for providing anatomical motion representation during thrust manipulation. Three unembalmed specimens were included in the study. Restricted dissection was realized to attach technical clusters to each bone of interest (skull, C1-C4 and sternum). During manipulation, bone motion data was computed using an optoelectronic system. The reliability of manipulation kinematics was assessed for three experimented practitioners performing two trials of 3 repetitions on two separate days. During UCS manipulation, average global head-trunk motion ROM (±SD) were 14 ± 5°, 35 ± 7° and 14 ± 8° for lateral bending, axial rotation and flexion-extension, respectively. For regional ROM (C0-C2), amplitudes were 10 ± 5°, 30 ± 5° and 16 ± 4° for the same respective motions. Concerning the reliability, mean RMS ranged from 1° to 4° and from 3° to 6° for intra- and inter-rater comparisons, respectively. The present results confirm the limited angular displacement during manipulation either for global head-trunk or for UCS motion components, especially for axial rotation. Additionally, kinematics variability was low confirming intra- and inter-practitioners consistency of UCS manipulation achievement.

  5. 3D quantitative evaluation of spine proprioceptive perception/motor control through instinctive self-correction manoeuvre in healthy young subjects' posture: an observational study.

    PubMed

    D'Amico, Moreno; Kinel, Edyta; Roncoletta, Piero

    2017-07-18

    Conservative treatment in spine deformities and spine related disorders is mainly based on proper individual proprioceptive and motor control training. For these reasons, conservative treatment involves the stimulation of individual capability of perceiving/reducing deformities, blocks and/or improper spine posture by voluntary control. The literature describes that habitually adopted relaxed postures often exacerbate low back pain. Typically, youths can be referred to therapeutic programs aimed at improving the quality of body posture along with fostering the awareness of the importance of correct posture. Few studies in literature outline the subject's individual instinctive ability to perceive properly and control his/her posture and produce an improvement through a self- correction manoeuvre. How do healthy young adult subjects perceive and control their posture and spine shape? Are they able to modify them in a correct way through an instinctive self-correction manoeuvre? Cross-sectional observational study. A cohort of asymptomatic young adult university students and workers were recruited at Clinic of Rehabilitation, University of Medical Sciences, Poznan, Poland. 121 healthy subjects (57 females, 64 males), 19-34 years (μ=23.5±3.2). Subject's full body posture including 3D spine shape reconstruction, identified using 27 retro-reflective markers suitably located on anatomical landmarks has been measured by using a non-ionizing 3D optoelectronic stereo-photogrammetric approach and a 3D full skeleton biomechanical model. From the 3D full skeleton and spine reconstruction, eleven quantitative biomechanical parameters describing the nature of body posture have been computed to compare Natural erect Vs Self-corrected standing attitudes. A high percentage of healthy participants 105(87%) was unable to modify its spinal shape in the frontal plane. Conversely, the sagittal plane presented significant clinical changes in the thoracic spine, where Males showed to

  6. Splice variants of the CaV1.3 L-type calcium channel regulate dendritic spine morphology

    PubMed Central

    Stanika, Ruslan; Campiglio, Marta; Pinggera, Alexandra; Lee, Amy; Striessnig, Jörg; Flucher, Bernhard E.; Obermair, Gerald J.

    2016-01-01

    Dendritic spines are the postsynaptic compartments of glutamatergic synapses in the brain. Their number and shape are subject to change in synaptic plasticity and neurological disorders including autism spectrum disorders and Parkinson’s disease. The L-type calcium channel CaV1.3 constitutes an important calcium entry pathway implicated in the regulation of spine morphology. Here we investigated the importance of full-length CaV1.3L and two C-terminally truncated splice variants (CaV1.342A and CaV1.343S) and their modulation by densin-180 and shank1b for the morphology of dendritic spines of cultured hippocampal neurons. Live-cell immunofluorescence and super-resolution microscopy of epitope-tagged CaV1.3L revealed its localization at the base-, neck-, and head-region of dendritic spines. Expression of the short splice variants or deletion of the C-terminal PDZ-binding motif in CaV1.3L induced aberrant dendritic spine elongation. Similar morphological alterations were induced by co-expression of densin-180 or shank1b with CaV1.3L and correlated with increased CaV1.3 currents and dendritic calcium signals in transfected neurons. Together, our findings suggest a key role of CaV1.3 in regulating dendritic spine structure. Under physiological conditions it may contribute to the structural plasticity of glutamatergic synapses. Conversely, altered regulation of CaV1.3 channels may provide an important mechanism in the development of postsynaptic aberrations associated with neurodegenerative disorders. PMID:27708393

  7. Suppressor of Cytokine Signalling 2 (SOCS2) Regulates Numbers of Mature Newborn Adult Hippocampal Neurons and Their Dendritic Spine Maturation.

    PubMed

    Basrai, Harleen S; Turbic, Alisa; Christie, Kimberly J; Turnley, Ann M

    2017-07-01

    Overexpression of suppressor of cytokine signalling 2 (SOCS2) has been shown to promote hippocampal neurogenesis in vivo and promote neurite outgrowth of neurons in vitro. In the adult mouse brain, SOCS2 is most highly expressed in the hippocampal CA3 region and at lower levels in the dentate gyrus, an expression pattern that suggests a role in adult neurogenesis. Herein we examine generation of neuroblasts and their maturation into more mature neurons in SOCS2 null (SOCS2KO) mice. EdU was administered for 7 days to label proliferative neural precursor cells. The number of EdU-labelled doublecortin(+) neuroblasts and NeuN(+) mature neurons they generated was examined at day 8 and day 35, respectively. While no effect of SOCS2 deletion was observed in neuroblast generation, it reduced the numbers of EdU-labelled mature newborn neurons at 35 days. As SOCS2 regulates neurite outgrowth and dentate granule neurons project to the CA3 region, alterations in dendritic arborisation or spine formation may have correlated with the decreased numbers of EdU-labelled newborn neurons. SOCS2KO mice were crossed with Nes-CreER(T2)/mTmG mice, in which membrane eGFP is inducibly expressed in neural precursor cells and their progeny, and the dendrite and dendritic spine morphology of newborn neurons were examined at 35 days. SOCS2 deletion had no effect on total dendrite length, number of dendritic segments, number of branch points or total dendritic spine density but increased the number of mature "mushroom" spines. Our results suggest that endogenous SOCS2 regulates numbers of EdU-labelled mature newborn adult hippocampal neurons, possibly by mediating their survival and that this may be via a mechanism regulating dendritic spine maturation.

  8. Visualization and genetic manipulation of dendrites and spines in the mouse cerebral cortex and hippocampus using in utero electroporation.

    PubMed

    Pacary, Emilie; Haas, Matilda A; Wildner, Hendrik; Azzarelli, Roberta; Bell, Donald M; Abrous, Djoher Nora; Guillemot, François

    2012-07-26

    In utero electroporation (IUE) has become a powerful technique to study the development of different regions of the embryonic nervous system (1-5). To date this tool has been widely used to study the regulation of cellular proliferation, differentiation and neuronal migration especially in the developing cerebral cortex (6-8). Here we detail our protocol to electroporate in utero the cerebral cortex and the hippocampus and provide evidence that this approach can be used to study dendrites and spines in these two cerebral regions. Visualization and manipulation of neurons in primary cultures have contributed to a better understanding of the processes involved in dendrite, spine and synapse development. However neurons growing in vitro are not exposed to all the physiological cues that can affect dendrite and/or spine formation and maintenance during normal development. Our knowledge of dendrite and spine structures in vivo in wild-type or mutant mice comes mostly from observations using the Golgi-Cox method( 9). However, Golgi staining is considered to be unpredictable. Indeed, groups of nerve cells and fiber tracts are labeled randomly, with particular areas often appearing completely stained while adjacent areas are devoid of staining. Recent studies have shown that IUE of fluorescent constructs represents an attractive alternative method to study dendrites, spines as well as synapses in mutant / wild-type mice (10-11) (Figure 1A). Moreover in comparison to the generation of mouse knockouts, IUE represents a rapid approach to perform gain and loss of function studies in specific population of cells during a specific time window. In addition, IUE has been successfully used with inducible gene expression or inducible RNAi approaches to refine the temporal control over the expression of a gene or shRNA (12). These advantages of IUE have thus opened new dimensions to study the effect of gene expression/suppression on dendrites and spines not only in specific cerebral

  9. Visualization and Genetic Manipulation of Dendrites and Spines in the Mouse Cerebral Cortex and Hippocampus using In utero Electroporation

    PubMed Central

    Pacary, Emilie; Haas, Matilda A.; Wildner, Hendrik; Azzarelli, Roberta; Bell, Donald M.; Abrous, Djoher Nora; Guillemot, François

    2012-01-01

    In utero electroporation (IUE) has become a powerful technique to study the development of different regions of the embryonic nervous system 1-5. To date this tool has been widely used to study the regulation of cellular proliferation, differentiation and neuronal migration especially in the developing cerebral cortex 6-8. Here we detail our protocol to electroporate in utero the cerebral cortex and the hippocampus and provide evidence that this approach can be used to study dendrites and spines in these two cerebral regions. Visualization and manipulation of neurons in primary cultures have contributed to a better understanding of the processes involved in dendrite, spine and synapse development. However neurons growing in vitro are not exposed to all the physiological cues that can affect dendrite and/or spine formation and maintenance during normal development. Our knowledge of dendrite and spine structures in vivo in wild-type or mutant mice comes mostly from observations using the Golgi-Cox method 9. However, Golgi staining is considered to be unpredictable. Indeed, groups of nerve cells and fiber tracts are labeled randomly, with particular areas often appearing completely stained while adjacent areas are devoid of staining. Recent studies have shown that IUE of fluorescent constructs represents an attractive alternative method to study dendrites, spines as well as synapses in mutant / wild-type mice 10-11 (Figure 1A). Moreover in comparison to the generation of mouse knockouts, IUE represents a rapid approach to perform gain and loss of function studies in specific population of cells during a specific time window. In addition, IUE has been successfully used with inducible gene expression or inducible RNAi approaches to refine the temporal control over the expression of a gene or shRNA 12. These advantages of IUE have thus opened new dimensions to study the effect of gene expression/suppression on dendrites and spines not only in specific cerebral structures

  10. Fear extinction deficits following acute stress associate with increased spine density and dendritic retraction in basolateral amygdala neurons

    PubMed Central

    Maroun, Mouna; Ioannides, Pericles J.; Bergman, Krista L.; Kavushansky, Alexandra; Holmes, Andrew; Wellman, Cara L.

    2013-01-01

    Stress-sensitive psychopathologies such as post-traumatic stress disorder are characterized by deficits in fear extinction and dysfunction of corticolimbic circuits mediating extinction. Chronic stress facilitates fear conditioning, impairs extinction, and produces dendritic proliferation in the basolateral amygdala (BLA), a critical site of plasticity for extinction. Acute stress impairs extinction, alters plasticity in the medial prefrontal cortex-to-BLA circuit, and causes dendritic retraction in the medial prefrontal cortex. Here, we examined extinction learning and basolateral amygdala pyramidal neuron morphology in adult male rats following a single elevated platform stress. Acute stress impaired extinction acquisition and memory, and produced dendritic retraction and increased mushroom spine density in basolateral amygdala neurons in the right hemisphere. Unexpectedly, irrespective of stress, rats that underwent fear and extinction testing showed basolateral amygdala dendritic retraction and altered spine density relative to non-conditioned rats, particularly in the left hemisphere. Thus, extinction deficits produced by acute stress are associated with increased spine density and dendritic retraction in basolateral amygdala pyramidal neurons. Furthermore, the finding that conditioning and extinction as such was sufficient to alter basolateral amygdala morphology and spine density illustrates the sensitivity of basolateral amygdala morphology to behavioral manipulation. These findings may have implications for elucidating the role of the amygdala in the pathophysiology of stress-related disorders. PMID:23714419

  11. Cux1 and Cux2 regulate dendritic branching, spine morphology and synapses of the upper layer neurons of the cortex

    PubMed Central

    Cubelos, Beatriz; Sebastián-Serrano, Alvaro; Beccari, Leonardo; Calcagnotto, Maria Elisa; Cisneros, Elsa; Kim, Seonhee; Dopazo, Ana; Alvarez-Dolado, Manuel; Redondo, Juan Miguel; Bovolenta, Paola; Walsh, Christopher A.; Nieto, Marta

    2010-01-01

    Summary Dendrite branching and spine formation determines the function of morphologically distinct and specialized neuronal subclasses. However, little is known about the programs instructing specific branching patterns in vertebrate neurons and whether such programs influence dendritic spines and synapses. Using knockout and knockdown studies combined with morphological, molecular and electrophysiological analysis we show that the homeobox Cux1 and Cux2 are intrinsic and complementary regulators of dendrite branching, spine development and synapse formation in layer II–III neurons of the cerebral cortex. Cux genes control the number and maturation of dendritic spines partly through direct regulation of the expression of Xlr3b and Xlr4b, chromatin remodeling genes previously implicated in cognitive defects. Accordingly, abnormal dendrites and synapses in Cux2−/− mice correlate with reduced synaptic function and defects in working memory. These demonstrate critical roles of Cux in dendritogenesis and highlight novel subclass-specific mechanisms of synapse regulation that contribute to the establishment of cognitive circuits. PMID:20510857

  12. Reproductive experience modified dendritic spines on cortical pyramidal neurons to enhance sensory perception and spatial learning in rats

    PubMed Central

    Chen, Jeng-Rung; Lim, Seh Hong; Chung, Sin-Cun; Lee, Yee-Fun; Wang, Yueh-Jan; Tseng, Guo-Fang; Wang, Tsyr-Jiuan

    2016-01-01

    Behavioral adaptations during motherhood are aimed at increasing reproductive success. Alterations of hormones during motherhood could trigger brain morphological changes to underlie behavioral alterations. Here we investigated whether motherhood changes a rat’s sensory perception and spatial memory in conjunction with cortical neuronal structural changes. Female rats of different statuses, including virgin, pregnant, lactating, and primiparous rats were studied. Behavioral test showed that the lactating rats were most sensitive to heat, while rats with motherhood and reproduction experience outperformed virgin rats in a water maze task. By intracellular dye injection and computer-assisted 3-dimensional reconstruction, the dendritic arbors and spines of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons were revealed for closer analysis. The results showed that motherhood and reproductive experience increased dendritic spines but not arbors or the lengths of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons. In addition, lactating rats had a higher incidence of spines than pregnant or primiparous rats. The increase of dendritic spines was coupled with increased expression of the glutamatergic postsynaptic marker protein (PSD-95), especially in lactating rats. On the basis of the present results, it is concluded that motherhood enhanced rat sensory perception and spatial memory and was accompanied by increases in dendritic spines on output neurons of the somatosensory cortex and CA1 hippocampus. The effect was sustained for at least 6 weeks after the weaning of the pups. PMID:27784858

  13. Matrix Metalloproteinases Regulate the Formation of Dendritic Spine Head Protrusions during Chemically Induced Long-Term Potentiation

    PubMed Central

    Szepesi, Zsuzsanna; Bijata, Monika; Ruszczycki, Blazej; Kaczmarek, Leszek; Wlodarczyk, Jakub

    2013-01-01

    Dendritic spines are are small membranous protrusions that extend from neuronal dendrites and harbor the majority of excitatory synapses. Increasing evidence has shown that matrix metalloproteinases (MMPs), a family of extracellularly acting and Zn2+-dependent endopeptidases, are able to rapidly modulate dendritic spine morphology. Spine head protrusions (SHPs) are filopodia-like processes that extend from the dendritic spine head, representing a form of postsynaptic structural remodeling in response to altered neuronal activity. Herein, we show that chemically induced long-term potentiation (cLTP) in dissociated hippocampal cultures upregulates MMP-9 activity that controls the formation of SHPs. Blocking of MMPs activity or microtubule dynamics abolishes the emergence of SHPs. In addition, autoactive recombinant MMP-9, promotes the formation of SHPs in organotypic hippocampal slices. Furthermore, spines with SHPs gained postsynaptic α-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA) receptors upon cLTP and the synaptic delivery of AMPA receptors was controlled by MMPs. The present results strongly imply that MMP-9 is functionally involved in the formation of SHPs and the control of postsynaptic receptor distribution upon cLTP. PMID:23696812

  14. Reproductive experience modified dendritic spines on cortical pyramidal neurons to enhance sensory perception and spatial learning in rats.

    PubMed

    Chen, Jeng-Rung; Lim, Seh Hong; Chung, Sin-Cun; Lee, Yee-Fun; Wang, Yueh-Jan; Tseng, Guo-Fang; Wang, Tsyr-Jiuan

    2017-01-27

    Behavioral adaptations during motherhood are aimed at increasing reproductive success. Alterations of hormones during motherhood could trigger brain morphological changes to underlie behavioral alterations. Here we investigated whether motherhood changes a rat's sensory perception and spatial memory in conjunction with cortical neuronal structural changes. Female rats of different statuses, including virgin, pregnant, lactating, and primiparous rats were studied. Behavioral test showed that the lactating rats were most sensitive to heat, while rats with motherhood and reproduction experience outperformed virgin rats in a water maze task. By intracellular dye injection and computer-assisted 3-dimensional reconstruction, the dendritic arbors and spines of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons were revealed for closer analysis. The results showed that motherhood and reproductive experience increased dendritic spines but not arbors or the lengths of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons. In addition, lactating rats had a higher incidence of spines than pregnant or primiparous rats. The increase of dendritic spines was coupled with increased expression of the glutamatergic postsynaptic marker protein (PSD-95), especially in lactating rats. On the basis of the present results, it is concluded that motherhood enhanced rat sensory perception and spatial memory and was accompanied by increases in dendritic spines on output neurons of the somatosensory cortex and CA1 hippocampus. The effect was sustained for at least 6 weeks after the weaning of the pups.

  15. Effect of tibolone on dendritic spine density in the rat hippocampus.

    PubMed

    Beltrán-Campos, V; Díaz-Ruiz, A; Padilla-Gómez, E; Aguilar Zavala, H; Ríos, C; Díaz Cintra, S

    2015-09-01

    Oestrogen deficiency produces oxidative stress (OS) and changes in hippocampal neurons and also reduces the density of dendritic spines (DS). These alterations affect the plastic response of the hippocampus. Oestrogen replacement therapy reverses these effects, but it remains to be seen whether the same changes are produced by tibolone (TB). The aim of this study was to test the neuroprotective effects of long-term oral TB treatment and its ability to reverse DS pruning in pyramidal neurons (PN) of hippocampal area CA1. Young Sprague Dawley rats were distributed in 3 groups: a control group in proestrus (Pro) and two ovariectomised groups (Ovx), of which one was provided with a daily TB dose (1mg/kg), OvxTB and the other with vehicle (OvxV), for 40 days in both cases. We analysed lipid peroxidation and DS density in 3 segments of apical dendrites from PNs in hippocampal area CA1. TB did not reduce lipid peroxidation but it did reverse the spine pruning in CA1 pyramidal neurons of the hippocampus which had been caused by ovariectomy. Oestrogen replacement therapy for ovariectomy-induced oestrogen deficiency has a protective effect on synaptic plasticity in the hippocampus. Copyright © 2014 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.

  16. Layer 4 pyramidal neurons exhibit robust dendritic spine plasticity in vivo after input deprivation.

    PubMed

    Miquelajauregui, Amaya; Kribakaran, Sahana; Mostany, Ricardo; Badaloni, Aurora; Consalez, G Giacomo; Portera-Cailliau, Carlos

    2015-05-06

    Pyramidal neurons in layers 2/3 and 5 of primary somatosensory cortex (S1) exhibit somewhat modest synaptic plasticity after whisker input deprivation. Whether neurons involved at earlier steps of sensory processing show more or less plasticity has not yet been examined. Here, we used longitudinal in vivo two-photon microscopy to investigate dendritic spine dynamics in apical tufts of GFP-expressing layer 4 (L4) pyramidal neurons of the vibrissal (barrel) S1 after unilateral whisker trimming. First, we characterize the molecular, anatomical, and electrophysiological properties of identified L4 neurons in Ebf2-Cre transgenic mice. Next, we show that input deprivation results in a substantial (∼50%) increase in the rate of dendritic spine loss, acutely (4-8 d) after whisker trimming. This robust synaptic plasticity in L4 suggests that primary thalamic recipient pyramidal neurons in S1 may be particularly sensitive to changes in sensory experience. Ebf2-Cre mice thus provide a useful tool for future assessment of initial steps of sensory processing in S1.

  17. Colocalization of integrin receptors and reelin in dendritic spine postsynaptic densities of adult nonhuman primate cortex

    PubMed Central

    Rodriguez, Miguel A.; Pesold, Christine; Liu, Wen S.; Kriho, Virginia; Guidotti, Alessandro; Pappas, George D.; Costa, Erminio

    2000-01-01

    The expression of telencephalic reelin (Reln) and glutamic acid decarboxylase mRNAs and their respective cognate proteins is down-regulated in postmortem brains of schizophrenia and bipolar disorder patients. To interpret the pathophysiological significance of this finding, immunoelectron microscopic experiments are required, but these cannot be carried out in postmortem human brains. As an alternative, we carried out such experiments in the cortex of rats and nonhuman primates. We found that Reln is expressed predominantly in layer I of both cortices and is localized to bitufted (double-bouquet), horizontal, and multipolar γ-aminobutyric acid-ergic interneurons, which secrete Reln into extracellular matrix. Reln secretion is mediated by a constitutive mechanism that depends on the expression of a specific signal peptide present in the Reln carboxy-terminal domain. Extracellular matrix Reln is found to aggregate in proximity of postsynaptic densities expressed in apical dendrite spines, which include also the α3 subunit of integrin receptors. Most pyramidal neurons of various cortical layers express the mouse-disabled 1 (Dab1) protein, which, after phosphorylation by a soluble tyrosine kinase, functions as an adapter protein, probably mediating a modulation of cytoskeleton protein expression. We hypothesize that the decrease of neuropil and dendritic spine density reported to exist in the neocortex of psychiatric patients may be related to a down-regulation of Reln–integrin interactions and the consequent decrease of cytoskeleton protein turnover. PMID:10725376

  18. Stress-induced alterations in prefrontal dendritic spines: Implications for post-traumatic stress disorder.

    PubMed

    Moench, Kelly M; Wellman, Cara L

    2015-08-05

    The medial prefrontal cortex (mPFC) is involved in a variety of important functions including emotional regulation, HPA axis regulation, and working memory. It also demonstrates remarkable plasticity in an experience-dependent manner. There is extensive evidence that stressful experiences can produce profound changes in the morphology of neurons within mPFC with a variety of behavioral consequences. The deleterious behavioral outcomes associated with mPFC dysfunction have been implicated in multiple psychopathologies, including post-traumatic stress disorder (PTSD). Given the prevalence of these disorders, a deeper understanding of the cellular mechanisms underlying stress-induced morphological changes in mPFC is critical, and could lead to improved therapeutic treatments. Here we give a brief review of recent studies examining the mechanisms underlying changes in mPFC pyramidal neuron dendritic spines - the primary sites of excitatory input in cortical pyramidal neurons. We begin with an overview of the effects of chronic stress on mPFC dendritic spine density and morphology followed by proposed mechanisms for these changes. We then discuss the time course of stress effects on mPFC as well as potential intercellular influences. Given that many psychopathologies, including PTSD, have different prevalence rates among men and women, we end with a discussion of the sex differences that have been observed in morphological changes in mPFC. Future directions and implications for PTSD are discussed throughout. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  19. WIP modulates dendritic spine actin cytoskeleton by transcriptional control of lipid metabolic enzymes.

    PubMed

    Franco-Villanueva, Ana; Fernández-López, Estefanía; Gabandé-Rodríguez, Enrique; Bañón-Rodríguez, Inmaculada; Esteban, Jose Antonio; Antón, Inés M; Ledesma, María Dolores

    2014-08-15

    We identify Wiskott-Aldrich syndrome protein (WASP)-interacting protein (WIP) as a novel component of neuronal synapses whose absence increases dendritic spine size and filamentous actin levels in an N-WASP/Arp2/3-independent, RhoA/ROCK/profilinIIa-dependent manner. These effects depend on the reduction of membrane sphingomyelin (SM) due to transcriptional upregulation of neutral sphingomyelinase (NSM) through active RhoA; this enhances RhoA binding to the membrane, raft partitioning and activation in steady state but prevents RhoA changes in response to stimulus. Inhibition of NSM or SM addition reverses RhoA, filamentous actin and functional anomalies in synapses lacking WIP. Our findings characterize WIP as a link between membrane lipid composition and actin cytoskeleton at dendritic spines. They also contribute to explain cognitive deficits shared by individuals bearing mutations in the region assigned to the gene encoding for WIP. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Hippocampal neuro-networks and dendritic spine perturbations in epileptogenesis are attenuated by neuroprotectin d1.

    PubMed

    Musto, Alberto E; Walker, Chelsey P; Petasis, Nicos A; Bazan, Nicolas G

    2015-01-01

    Limbic epileptogenesis triggers molecular and cellular events that foster the establishment of aberrant neuronal networks that, in turn, contribute to temporal lobe epilepsy (TLE). Here we have examined hippocampal neuronal network activities in the pilocarpine post-status epilepticus model of limbic epileptogenesis and asked whether or not the docosahexaenoic acid (DHA)-derived lipid mediator, neuroprotectin D1 (NPD1), modulates epileptogenesis. Status epilepticus (SE) was induced by intraperitoneal administration of pilocarpine in adult male C57BL/6 mice. To evaluate simultaneous hippocampal neuronal networks, local field potentials were recorded from multi-microelectrode arrays (silicon probe) chronically implanted in the dorsal hippocampus. NPD1 (570 μg/kg) or vehicle was administered intraperitoneally daily for five consecutive days 24 hours after termination of SE. Seizures and epileptiform activity were analyzed in freely-moving control and treated mice during epileptogenesis and epileptic periods. Then hippocampal dendritic spines were evaluated using Golgi-staining. We found brief spontaneous microepileptiform activity with high amplitudes in the CA1 pyramidal and stratum radiatum in epileptogenesis. These aberrant activities were attenuated following systemic NPD1 administration, with concomitant hippocampal dendritic spine protection. Moreover, NPD1 treatment led to a reduction in spontaneous recurrent seizures. Our results indicate that NPD1 displays neuroprotective bioactivity on the hippocampal neuronal network ensemble that mediates aberrant circuit activity during epileptogenesis. Insight into the molecular signaling mediated by neuroprotective bioactivity of NPD1 on neuronal network dysfunction may contribute to the development of anti-epileptogenic therapeutic strategies.

  1. Dendritic spine plasticity in gonadatropin-releasing hormone (GnRH) neurons activated at the time of the preovulatory surge.

    PubMed

    Chan, Heidi; Prescott, Melanie; Ong, ZhiYi; Herde, Michel K; Herbison, Allan E; Campbell, Rebecca E

    2011-12-01

    GnRH neuron activity is dependent on gonadal steroid hormone feedback. Altered synaptic input may be one mechanism by which steroids modify GnRH neuron activity. In other neuronal populations, steroid hormones have been shown to elicit profound effects on dendritic spine density, a measure of excitatory synaptic input. The present study examined gonadal steroid feedback effects on GnRH neuron spine density in female GnRH-green fluorescent protein (GFP) mice. Immunocytochemical labeling of GFP in this model reveals fine morphological details of GnRH neurons. Spine density and other features were quantified by confocal analysis. Ovariectomy resulted in a significant reduction in somatic spine density (27%, P < 0.05) compared with sham-operated diestrous females. However, dendritic spine density was unaltered. Positive feedback effects of estradiol on spine density were investigated using a protocol to mimic the GnRH/LH surge. Ten GnRH-GFP mice underwent an established protocol, receiving either estradiol benzoate (1 μg per 20 g body weight) or vehicle (n = 5/group) 32 h prior to being killed during the expected surge. Double-label immunofluorescence showed that all estradiol-treated females expressed cFos in a subpopulation of GnRH neurons. Spine density was determined by confocal analysis of activated (cFos-positive, n = 10 neurons/animal) and nonactivated (cFos-negative, n = 10 neurons/animal) GnRH neurons from estradiol-treated animals and for GnRH neurons (n = 20 neurons/animal) from nonsurged controls (all cFos negative). Activated GnRH neurons (cFos positive) showed a dramatic 60% increase in total spine density (0.78 ± 0.06 spines/μm) compared with nonactivated GnRH neurons (0.50 ± 0.01 spines/μm) in estradiol-treated animals (P < 0.001). Both somatic and dendritic spine density was significantly increased. Spine density was not different between nonactivated GnRH neurons from surged animals (0.50 ± 0.01 spines/μm) and GnRH neurons from nonsurged

  2. Super resolution microscopy is poised to reveal new insights into the formation and maturation of dendritic spines

    PubMed Central

    Robinson, Cristina M.; Patel, Mikin R.; Webb, Donna J.

    2016-01-01

    Dendritic spines and synapses are critical for neuronal communication, and they are perturbed in many neurological disorders; however, the study of these structures in living cells has been hindered by their small size. Super resolution microscopy, unlike conventional light microscopy, is diffraction unlimited and thus is well suited for imaging small structures, such as dendritic spines and synapses. Super resolution microscopy has already revealed important new information about spine and synapse morphology, actin remodeling, and nanodomain composition in both healthy cells and diseased states. In this review, we highlight the advancements in probes that make super resolution more amenable to live-cell imaging of spines and synapses. We also discuss recent data obtained by super resolution microscopy that has advanced our knowledge of dendritic spine and synapse structure, organization, and dynamics in both healthy and diseased contexts. Finally, we propose a series of critical questions for understanding spine and synapse formation and maturation that super resolution microscopy is poised to answer. PMID:27408691

  3. Brainstem immaturity in sudden infant death syndrome: a quantitative rapid Golgi study of dendritic spines in 95 infants.

    PubMed

    Quattrochi, J J; McBride, P T; Yates, A J

    1985-01-28

    Quantitative analysis of reticular dendritic spines was performed on rapid Golgi impregnated neurons in 7 brainstem areas from 61 sudden infant death syndrome (SIDS) and 34 control infants. Throughout the first postnatal year, mean spine density in SIDS was significantly greater than the mean density in controls (P less than 0.0001). There were significantly higher values of spine density in SIDS compared to controls (P less than 0.0001) in both term and preterm infants. Within the SIDS brainstem itself, the density of dendritic spines was significantly different (P less than 0.05) between two medullary regions and between reticular and non-reticular formation areas. Among these brainstem areas in controls, there was no significant difference. Our findings indicate an immature developmental pattern of increased dendritic spine density in the SIDS brainstem which may be responsible for abnormal central respiratory and arousal control. These significant quantitative differences in spine density are considered in the present study to represent an anatomical substrate of brainstem immaturity in the multifactorial pathogenesis of SIDS.

  4. Glutamatergic regulation prevents hippocampal-dependent age-related cognitive decline through dendritic spine clustering

    PubMed Central

    Pereira, Ana C.; Lambert, Hilary K.; Grossman, Yael S.; Dumitriu, Dani; Waldman, Rachel; Jannetty, Sophia K.; Calakos, Katina; Janssen, William G.; McEwen, Bruce S.; Morrison, John H.

    2014-01-01

    The dementia of Alzheimer’s disease (AD) results primarily from degeneration of neurons that furnish glutamatergic corticocortical connections that subserve cognition. Although neuron death is minimal in the absence of AD, age-related cognitive decline does occur in animals as well as humans, and it decreases quality of life for elderly people. Age-related cognitive decline has been linked to synapse loss and/or alterations of synaptic proteins that impair function in regions such as the hippocampus and prefrontal cortex. These synaptic alterations are likely reversible, such that maintenance of synaptic health in the face of aging is a critically important therapeutic goal. Here, we show that riluzole can protect against some of the synaptic alterations in hippocampus that are linked to age-related memory loss in rats. Riluzole increases glutamate uptake through glial transporters and is thought to decrease glutamate spillover to extrasynaptic NMDA receptors while increasing synaptic glutamatergic activity. Treated aged rats were protected against age-related cognitive decline displayed in nontreated aged animals. Memory performance correlated with density of thin spines on apical dendrites in CA1, although not with mushroom spines. Furthermore, riluzole-treated rats had an increase in clustering of thin spines that correlated with memory performance and was specific to the apical, but not the basilar, dendrites of CA1. Clustering of synaptic inputs is thought to allow nonlinear summation of synaptic strength. These findings further elucidate neuroplastic changes in glutamatergic circuits with aging and advance therapeutic development to prevent and treat age-related cognitive decline. PMID:25512503

  5. Single-Molecule Discrimination within Dendritic Spines of Discrete Perisynaptic Sites of Actin Filament Assembly Driving Postsynaptic Reorganization

    NASA Astrophysics Data System (ADS)

    Blanpied, Thomas A.

    2013-03-01

    In the brain, the strength of synaptic transmission between neurons is principally set by the organization of proteins within the receptive, postsynaptic cell. Synaptic strength at an individual site of contact can remain remarkably stable for months or years. However, it also can undergo diverse forms of plasticity which change the strength at that contact independent of changes to neighboring synapses. Such activity-triggered neural plasticity underlies memory storage and cognitive development, and is disrupted in pathological physiology such as addiction and schizophrenia. Much of the short-term regulation of synaptic plasticity occurs within the postsynaptic cell, in small subcompartments surrounding the synaptic contact. Biochemical subcompartmentalization necessary for synapse-specific plasticity is achieved in part by segregation of synapses to micron-sized protrusions from the cell called dendritic spines. Dendritic spines are heavily enriched in the actin cytoskeleton, and regulation of actin polymerization within dendritic spines controls both basal synaptic strength and many forms of synaptic plasticity. However, understanding the mechanism of this control has been difficult because the submicron dimensions of spines limit examination of actin dynamics in the spine interior by conventional confocal microscopy. To overcome this, we developed single-molecule tracking photoactivated localization microscopy (smtPALM) to measure the movement of individual actin molecules within living spines. This revealed inward actin flow from broad areas of the spine plasma membrane, as well as a dense central core of heterogeneous filament orientation. The velocity of single actin molecules along filaments was elevated in discrete regions within the spine, notably near the postsynaptic density but surprisingly not at the endocytic zone which is involved in some forms of plasticity. We conclude that actin polymerization is initiated at many well-separated foci within

  6. Cortical regulation of striatal medium spiny neuron dendritic remodeling in parkinsonism: modulation of glutamate release reverses dopamine depletion-induced dendritic spine loss.

    PubMed

    Garcia, Bonnie G; Neely, M Diana; Deutch, Ariel Y

    2010-10-01

    Striatal medium spiny neurons (MSNs) receive glutamatergic afferents from the cerebral cortex and dopaminergic inputs from the substantia nigra (SN). Striatal dopamine loss decreases the number of MSN dendritic spines. This loss of spines has been suggested to reflect the removal of tonic dopamine inhibitory control over corticostriatal glutamatergic drive, with increased glutamate release culminating in MSN spine loss. We tested this hypothesis in two ways. We first determined in vivo if decortication reverses or prevents dopamine depletion-induced spine loss by placing motor cortex lesions 4 weeks after, or at the time of, 6-hydroxydopamine lesions of the SN. Animals were sacrificed 4 weeks after cortical lesions. Motor cortex lesions significantly reversed the loss of MSN spines elicited by dopamine denervation; a similar effect was observed in the prevention experiment. We then determined if modulating glutamate release in organotypic cocultures prevented spine loss. Treatment of the cultures with the mGluR2/3 agonist LY379268 to suppress corticostriatal glutamate release completely blocked spine loss in dopamine-denervated cultures. These studies provide the first evidence to show that MSN spine loss associated with parkinsonism can be reversed and point to suppression of corticostriatal glutamate release as a means of slowing progression in Parkinson's disease.

  7. Withdrawal from chronic intermittent alcohol exposure increases dendritic spine density in the lateral orbitofrontal cortex of mice.

    PubMed

    McGuier, Natalie S; Padula, Audrey E; Lopez, Marcelo F; Woodward, John J; Mulholland, Patrick J

    2015-02-01

    Alcohol use disorders (AUDs) are associated with functional and morphological changes in subfields of the prefrontal cortex. Clinical and preclinical evidence indicates that the orbitofrontal cortex (OFC) is critical for controlling impulsive behaviors, representing the value of a predicted outcome, and reversing learned associations. Individuals with AUDs often demonstrate deficits in OFC-dependent tasks, and rodent models of alcohol exposure show that OFC-dependent behaviors are impaired by chronic alcohol exposure. To explore the mechanisms that underlie these impairments, we examined dendritic spine density and morphology, and NMDA-type glutamate receptor expression in the lateral OFC of C57BL/6J mice following chronic intermittent ethanol (CIE) exposure. Western blot analysis demonstrated that NMDA receptors were not altered immediately following CIE exposure or after 7 days of withdrawal. Morphological analysis of basal dendrites of layer II/III pyramidal neurons revealed that dendritic spine density was also not affected immediately after CIE exposure. However, the total density of dendritic spines was significantly increased after a 7-day withdrawal from CIE exposure. The effect of withdrawal on spine density was mediated by an increase in the density of long, thin spines with no change in either stubby or mushroom spines. These data suggest that morphological neuroadaptations in lateral OFC neurons develop during alcohol withdrawal and occur in the absence of changes in the expression of NMDA-type glutamate receptors. The enhanced spine density that follows alcohol withdrawal may contribute to the impairments in OFC-dependent behaviors observed in CIE-treated mice.

  8. Robust 3D-2D image registration: application to spine interventions and vertebral labeling in the presence of anatomical deformation

    NASA Astrophysics Data System (ADS)

    Otake, Yoshito; Wang, Adam S.; Webster Stayman, J.; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Khanna, A. Jay; Gokaslan, Ziya L.; Siewerdsen, Jeffrey H.

    2013-12-01

    We present a framework for robustly estimating registration between a 3D volume image and a 2D projection image and evaluate its precision and robustness in spine interventions for vertebral localization in the presence of anatomical deformation. The framework employs a normalized gradient information similarity metric and multi-start covariance matrix adaptation evolution strategy optimization with local-restarts, which provided improved robustness against deformation and content mismatch. The parallelized implementation allowed orders-of-magnitude acceleration in computation time and improved the robustness of registration via multi-start global optimization. Experiments involved a cadaver specimen and two CT datasets (supine and prone) and 36 C-arm fluoroscopy images acquired with the specimen in four positions (supine, prone, supine with lordosis, prone with kyphosis), three regions (thoracic, abdominal, and lumbar), and three levels of geometric magnification (1.7, 2.0, 2.4). Registration accuracy was evaluated in terms of projection distance error (PDE) between the estimated and true target points in the projection image, including 14 400 random trials (200 trials on the 72 registration scenarios) with initialization error up to ±200 mm and ±10°. The resulting median PDE was better than 0.1 mm in all cases, depending somewhat on the resolution of input CT and fluoroscopy images. The cadaver experiments illustrated the tradeoff between robustness and computation time, yielding a success rate of 99.993% in vertebral labeling (with ‘success’ defined as PDE <5 mm) using 1,718 664 ± 96 582 function evaluations computed in 54.0 ± 3.5 s on a mid-range GPU (nVidia, GeForce GTX690). Parameters yielding a faster search (e.g., fewer multi-starts) reduced robustness under conditions of large deformation and poor initialization (99.535% success for the same data registered in 13.1 s), but given good initialization (e.g., ±5 mm, assuming a robust initial

  9. Robust 3D-2D image registration: application to spine interventions and vertebral labeling in the presence of anatomical deformation.

    PubMed

    Otake, Yoshito; Wang, Adam S; Webster Stayman, J; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Khanna, A Jay; Gokaslan, Ziya L; Siewerdsen, Jeffrey H

    2013-12-07

    We present a framework for robustly estimating registration between a 3D volume image and a 2D projection image and evaluate its precision and robustness in spine interventions for vertebral localization in the presence of anatomical deformation. The framework employs a normalized gradient information similarity metric and multi-start covariance matrix adaptation evolution strategy optimization with local-restarts, which provided improved robustness against deformation and content mismatch. The parallelized implementation allowed orders-of-magnitude acceleration in computation time and improved the robustness of registration via multi-start global optimization. Experiments involved a cadaver specimen and two CT datasets (supine and prone) and 36 C-arm fluoroscopy images acquired with the specimen in four positions (supine, prone, supine with lordosis, prone with kyphosis), three regions (thoracic, abdominal, and lumbar), and three levels of geometric magnification (1.7, 2.0, 2.4). Registration accuracy was evaluated in terms of projection distance error (PDE) between the estimated and true target points in the projection image, including 14 400 random trials (200 trials on the 72 registration scenarios) with initialization error up to ±200 mm and ±10°. The resulting median PDE was better than 0.1 mm in all cases, depending somewhat on the resolution of input CT and fluoroscopy images. The cadaver experiments illustrated the tradeoff between robustness and computation time, yielding a success rate of 99.993% in vertebral labeling (with 'success' defined as PDE <5 mm) using 1,718 664 ± 96 582 function evaluations computed in 54.0 ± 3.5 s on a mid-range GPU (nVidia, GeForce GTX690). Parameters yielding a faster search (e.g., fewer multi-starts) reduced robustness under conditions of large deformation and poor initialization (99.535% success for the same data registered in 13.1 s), but given good initialization (e.g., ±5 mm, assuming a robust initial run) the

  10. Wnt-5a/Frizzled9 Receptor Signaling through the Gαo-Gβγ Complex Regulates Dendritic Spine Formation.

    PubMed

    Ramírez, Valerie T; Ramos-Fernández, Eva; Henríquez, Juan Pablo; Lorenzo, Alfredo; Inestrosa, Nibaldo C

    2016-09-02

    Wnt ligands play crucial roles in the development and regulation of synapse structure and function. Specifically, Wnt-5a acts as a secreted growth factor that regulates dendritic spine formation in rodent hippocampal neurons, resulting in postsynaptic development that promotes the clustering of the PSD-95 (postsynaptic density protein 95). Here, we focused on the early events occurring after the interaction between Wnt-5a and its Frizzled receptor at the neuronal cell surface. Additionally, we studied the role of heterotrimeric G proteins in Wnt-5a-dependent synaptic development. We report that FZD9 (Frizzled9), a Wnt receptor related to Williams syndrome, is localized in the postsynaptic region, where it interacts with Wnt-5a. Functionally, FZD9 is required for the Wnt-5a-mediated increase in dendritic spine density. FZD9 forms a precoupled complex with Gαo under basal conditions that dissociates after Wnt-5a stimulation. Accordingly, we found that G protein inhibition abrogates the Wnt-5a-dependent pathway in hippocampal neurons. In particular, the activation of Gαo appears to be a key factor controlling the Wnt-5a-induced dendritic spine density. In addition, we found that Gβγ is required for the Wnt-5a-mediated increase in cytosolic calcium levels and spinogenesis. Our findings reveal that FZD9 and heterotrimeric G proteins regulate Wnt-5a signaling and dendritic spines in cultured hippocampal neurons. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Wnt-5a/Frizzled9 Receptor Signaling through the Gαo-Gβγ Complex Regulates Dendritic Spine Formation*

    PubMed Central

    Ramírez, Valerie T.; Ramos-Fernández, Eva; Henríquez, Juan Pablo; Lorenzo, Alfredo; Inestrosa, Nibaldo C.

    2016-01-01

    Wnt ligands play crucial roles in the development and regulation of synapse structure and function. Specifically, Wnt-5a acts as a secreted growth factor that regulates dendritic spine formation in rodent hippocampal neurons, resulting in postsynaptic development that promotes the clustering of the PSD-95 (postsynaptic density protein 95). Here, we focused on the early events occurring after the interaction between Wnt-5a and its Frizzled receptor at the neuronal cell surface. Additionally, we studied the role of heterotrimeric G proteins in Wnt-5a-dependent synaptic development. We report that FZD9 (Frizzled9), a Wnt receptor related to Williams syndrome, is localized in the postsynaptic region, where it interacts with Wnt-5a. Functionally, FZD9 is required for the Wnt-5a-mediated increase in dendritic spine density. FZD9 forms a precoupled complex with Gαo under basal conditions that dissociates after Wnt-5a stimulation. Accordingly, we found that G protein inhibition abrogates the Wnt-5a-dependent pathway in hippocampal neurons. In particular, the activation of Gαo appears to be a key factor controlling the Wnt-5a-induced dendritic spine density. In addition, we found that Gβγ is required for the Wnt-5a-mediated increase in cytosolic calcium levels and spinogenesis. Our findings reveal that FZD9 and heterotrimeric G proteins regulate Wnt-5a signaling and dendritic spines in cultured hippocampal neurons. PMID:27402827

  12. ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

    ERIC Educational Resources Information Center

    Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

  13. ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

    ERIC Educational Resources Information Center

    Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

  14. The effects of cocaine self-administration on dendritic spine density in the rat hippocampus are dependent on genetic background.

    PubMed

    Miguéns, Miguel; Kastanauskaite, Asta; Coria, Santiago M; Selvas, Abraham; Ballesteros-Yañez, Inmaculada; DeFelipe, Javier; Ambrosio, Emilio

    2015-01-01

    Chronic exposure to cocaine induces modifications to neurons in the brain regions involved in addiction. Hence, we evaluated cocaine-induced changes in the hippocampal CA1 field in Fischer 344 (F344) and Lewis (LEW) rats, 2 strains that have been widely used to study genetic predisposition to drug addiction, by combining intracellular Lucifer yellow injection with confocal microscopy reconstruction of labeled neurons. Specifically, we examined the effects of cocaine self-administration on the structure, size, and branching complexity of the apical dendrites of CA1 pyramidal neurons. In addition, we quantified spine density in the collaterals of the apical dendritic arbors of these neurons. We found differences between these strains in several morphological parameters. For example, CA1 apical dendrites were more branched and complex in LEW than in F344 rats, while the spine density in the collateral dendrites of the apical dendritic arbors was greater in F344 rats. Interestingly, cocaine self-administration in LEW rats augmented the spine density, an effect that was not observed in the F344 strain. These results reveal significant structural differences in CA1 pyramidal cells between these strains and indicate that cocaine self-administration has a distinct effect on neuron morphology in the hippocampus of rats with different genetic backgrounds. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Activation of β2-adrenergic receptor promotes dendrite ramification and spine generation in APP/PS1 mice.

    PubMed

    Chai, Gao-Shang; Wang, Yang-Yang; Zhu, Dan; Yasheng, Amina; Zhao, Peng

    2017-01-01

    Alzheimer's disease (AD) is the most common neurodegenerative disorder, and currently there is no effective cure for this devastating disease. Decreases in the levels of β2-adrenoceptor (β2-AR) and norepinephrine have been reported in several regions of AD brains. The activation of β2AR can prevent the amyloid β (Aβ)-mediated inhibition of LTP (Long-term potentiation), but the mechanism is not fully understood. Here, we used APP/PS1 mice to study whether the activation of β2AR could remodel synaptic and/or dendritic plasticity. We found that the activation of β2AR by Clenbuterol (Clen) ameliorated memory deficits and promoted dendrite ramification and spine generation in hippocampal CA1 neurons, which was accompanied by the upregulation of postsynaptic density protein 95 (PSD95), synapsin 1 and synaptophysin. Conversely, the inhibition of β2AR by a siRNA blocked the Clen-induced increase in dendrite ramification and dendritic spines in primary hippocampal neurons. Furthermore, the activation of β2AR decreased cerebral amyloid plaques through the up-regulation of α-secretase activity and by decreasing the phosphorylation of APP at Thr668. Based on the roles of β2AR in dendrite ramification and spine generation, memory deficits and AD pathogenesis, compounds designed to activate β2AR might shed light on the cure of AD. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Changes of dendritic spine density and morphology in the superficial layers of the medial entorhinal cortex induced by extremely low-frequency magnetic field exposure.

    PubMed

    Xiong, Jiaxiang; He, Chao; Li, Chao; Tan, Gang; Li, Jingcheng; Yu, Zhengping; Hu, Zhian; Chen, Fang

    2013-01-01

    In the present study, we investigated the effects of chronic exposure (14 and 28 days) to a 0.5 mT 50 Hz extremely low-frequency magnetic field (ELM) on the dendritic spine density and shape in the superficial layers of the medial entorhinal cortex (MEC). We performed Golgi staining to reveal the dendritic spines of the principal neurons in rats. The results showed that ELM exposure induced a decrease in the spine density in the dendrites of stellate neurons and the basal dendrites of pyramidal neurons at both 14 days and 28 days, which was largely due to the loss of the thin and branched spines. The alteration in the density of mushroom and stubby spines post ELM exposure was cell-type specific. For the stellate neurons, ELM exposure slightly increased the density of stubby spines at 28 days, while it did not affect the density of mushroom spines at the same time. In the basal dendrites of pyramidal neurons, we observed a significant decrease in the mushroom spine density only at the later time point post ELM exposure, while the stubby spine density was reduced at 14 days and partially restored at 28 days post ELM exposure. ELM exposure-induced reduction in the spine density in the apical dendrites of pyramidal neurons was only observed at 28 days, reflecting the distinct vulnerability of spines in the apical and basal dendrites. Considering the changes in spine number and shape are involved in synaptic plasticity and the MEC is a part of neural network that is closely related to learning and memory, these findings may be helpful for explaining the ELM exposure-induced impairment in cognitive functions.

  17. Expansion of mossy fibers and CA3 apical dendritic length accompanies the fall in dendritic spine density after gonadectomy in male, but not female, rats

    PubMed Central

    Mendell, Ari L.; Atwi, Sarah; Bailey, Craig D. C.; McCloskey, Dan; Scharfman, Helen E.

    2017-01-01

    Androgen loss is an important clinical concern because of its cognitive and behavioral effects. Changes in androgen levels are also suspected to contribute to neurological disease. However, the available data on the effects of androgen deprivation in areas of the brain that are central to cognition, like the hippocampus, are mixed. In this study, morphological analysis of pyramidal cells was used to investigate if structural changes could potentially contribute to the mixed cognitive effects that have been observed after androgen loss in males. Male Sprague–Dawley rats were orchidectomized or sham-operated. Two months later, their brains were Golgi-impregnated for morphological analysis. Morphological endpoints were studied in areas CA3 and CA1, with comparisons to females either intact or 2 months after ovariectomy. CA3 pyramidal neurons of orchidectomized rats exhibited marked increases in apical dendritic arborization. There were increases in mossy fiber afferent density in area CA3, as well as robust enhancements to dendritic structure in area CA3 of orchidectomized males, but not in CA1. Remarkably, apical dendritic length of CA3 pyramidal cells increased, while spine density declined. By contrast, in females overall dendritic structure was minimally affected by ovariectomy, while dendritic spine density was greatly reduced. Sex differences and subfield-specific effects of gonadal hormone deprivation on the hippocampal circuitry may help explain the different behavioral effects reported in males and females after gonadectomy, or other conditions associated with declining gonadal hormone secretion. PMID:27283589

  18. Automatic localization of target vertebrae in spine surgery using fast CT-to-fluoroscopy (3D-2D) image registration

    NASA Astrophysics Data System (ADS)

    Otake, Y.; Schafer, S.; Stayman, J. W.; Zbijewski, W.; Kleinszig, G.; Graumann, R.; Khanna, A. J.; Siewerdsen, J. H.

    2012-02-01

    Localization of target vertebrae is an essential step in minimally invasive spine surgery, with conventional methods relying on "level counting" - i.e., manual counting of vertebrae under fluoroscopy starting from readily identifiable anatomy (e.g., the sacrum). The approach requires an undesirable level of radiation, time, and is prone to counting errors due to the similar appearance of vertebrae in projection images; wrong-level surgery occurs in 1 of every ~3000 cases. This paper proposes a method to automatically localize target vertebrae in x-ray projections using 3D-2D registration between preoperative CT (in which vertebrae are preoperatively labeled) and intraoperative fluoroscopy. The registration uses an intensity-based approach with a gradient-based similarity metric and the CMA-ES algorithm for optimization. Digitally reconstructed radiographs (DRRs) and a robust similarity metric are computed on GPU to accelerate the process. Evaluation in clinical CT data included 5,000 PA and LAT projections randomly perturbed to simulate human variability in setup of mobile intraoperative C-arm. The method demonstrated 100% success for PA view (projection error: 0.42mm) and 99.8% success for LAT view (projection error: 0.37mm). Initial implementation on GPU provided automatic target localization within about 3 sec, with further improvement underway via multi-GPU. The ability to automatically label vertebrae in fluoroscopy promises to streamline surgical workflow, improve patient safety, and reduce wrong-site surgeries, especially in large patients for whom manual methods are time consuming and error prone.

  19. The role of heparan sulfate deficiency in autistic phenotype: potential involvement of Slit/Robo/srGAPs-mediated dendritic spine formation.

    PubMed

    Pérez, Christine; Sawmiller, Darrell; Tan, Jun

    2016-04-18

    Autism Spectrum Disorders (ASD) are the second most common developmental cause of disability in the United States. ASDs are accompanied with substantial economic and emotional cost. The brains of ASD patients have marked structural abnormalities, in the form of increased dendritic spines and decreased long distance connections. These structural differences may be due to deficiencies in Heparin Sulfate (HS), a proteoglycan involved in a variety of neurodevelopmental processes. Of particular interest is its role in the Slit/Robo pathway. The Slit/Robo pathway is known to be involved in the regulation of axonal guidance and dendritic spine formation. HS mediates the Slit/Robo interaction; without its presence Slit's repulsive activity is abrogated. Slit/Robo regulates dendritic spine formation through its interaction with srGAPs (slit-robo GTPase Activating Proteins), which leads to downstream signaling, actin cytoskeleton depolymerization and dendritic spine collapse. Through interference with this pathway, HS deficiency can lead to excess spine formation.

  20. [Three-dimensional reconstruction of synapse and dendritic spines in the hippocampus of rats and ground squirrels: new paradigms of the structure and function of a synapse].

    PubMed

    Popov, V I; Deev, A A; Klimenko, O A; Kraev, I V; Kuz'minykh, S B; Medvedev, N I; Patrushev, I V; Popov, R V; Rogachevskiĭ, V V; Khutsian, S S; Stewart, M G; Fesenko, E E

    2004-01-01

    The article reviews the literature data and results obtained by the authors concerning synaptic plasticity and remodeling of synaptic organelles in the central nervous system. Modern techniques of laser scanning confocal microscopy and serial thin sectioning for in vivo and in vitro studies of dendritic spines including a correlation between morphological changes and synaptic transmission efficiency are discussed, particularly, in relation to long-term potentiation. Organization of different types of dendritic spines and involvement of filopodia in spine genesis are examined. Significance of serial ultrathin sections for unbiased quantitative stereological analysis and three-dimensional reconstructions is discussed. The contact of one dendritic spine with two presynaptic boutons (multiple synapses) on both CA1 mushroom dendritic spines is discussed. The analyzed findings suggest new ideas for organization and functioning of synapses.

  1. Reelin Regulates the Maturation of Dendritic Spines, Synaptogenesis and Glial Ensheathment of Newborn Granule Cells.

    PubMed

    Bosch, Carles; Masachs, Nuria; Exposito-Alonso, David; Martínez, Albert; Teixeira, Cátia M; Fernaud, Isabel; Pujadas, Lluís; Ulloa, Fausto; Comella, Joan X; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2016-10-17

    The extracellular protein Reelin has an important role in neurological diseases, including epilepsy, Alzheimer's disease and psychiatric diseases, targeting hippocampal circuits. Here we address the role of Reelin in the development of synaptic contacts in adult-generated granule cells (GCs), a neuronal population that is crucial for learning and memory and implicated in neurological and psychiatric diseases. We found that the Reelin pathway controls the shapes, sizes, and types of dendritic spines, the complexity of multisynaptic innervations and the degree of the perisynaptic astroglial ensheathment that controls synaptic homeostasis. These findings show a pivotal role of Reelin in GC synaptogenesis and provide a foundation for structural circuit alterations caused by Reelin deregulation that may occur in neurological and psychiatric disorders.

  2. Asymptotic analysis of the narrow escape problem in dendritic spine shaped domain: three dimensions

    NASA Astrophysics Data System (ADS)

    Li, Xiaofei; Lee, Hyundae; Wang, Yuliang

    2017-08-01

    This paper deals with the three-dimensional narrow escape problem in a dendritic spine shaped domain, which is composed of a relatively big head and a thin neck. The narrow escape problem is to compute the mean first passage time of Brownian particles traveling from inside the head to the end of the neck. The original model is to solve a mixed Dirichlet-Neumann boundary value problem for the Poisson equation in the composite domain, and is computationally challenging. In this paper we seek to transfer the original problem to a mixed Robin-Neumann boundary value problem by dropping the thin neck part, and rigorously derive the asymptotic expansion of the mean first passage time with high order terms. This study is a nontrivial three-dimensional generalization of the work in Li (2014 J. Phys. A: Math. Theor. 47 505202), where a two-dimensional analogue domain is considered.

  3. Hippocampal Neuro-Networks and Dendritic Spine Perturbations in Epileptogenesis Are Attenuated by Neuroprotectin D1

    PubMed Central

    Musto, Alberto E.; Walker, Chelsey P.; Petasis, Nicos A.; Bazan, Nicolas G.

    2015-01-01

    Purpose Limbic epileptogenesis triggers molecular and cellular events that foster the establishment of aberrant neuronal networks that, in turn, contribute to temporal lobe epilepsy (TLE). Here we have examined hippocampal neuronal network activities in the pilocarpine post-status epilepticus model of limbic epileptogenesis and asked whether or not the docosahexaenoic acid (DHA)-derived lipid mediator, neuroprotectin D1 (NPD1), modulates epileptogenesis. Methods Status epilepticus (SE) was induced by intraperitoneal administration of pilocarpine in adult male C57BL/6 mice. To evaluate simultaneous hippocampal neuronal networks, local field potentials were recorded from multi-microelectrode arrays (silicon probe) chronically implanted in the dorsal hippocampus. NPD1 (570 μg/kg) or vehicle was administered intraperitoneally daily for five consecutive days 24 hours after termination of SE. Seizures and epileptiform activity were analyzed in freely-moving control and treated mice during epileptogenesis and epileptic periods. Then hippocampal dendritic spines were evaluated using Golgi-staining. Results We found brief spontaneous microepileptiform activity with high amplitudes in the CA1 pyramidal and stratum radiatum in epileptogenesis. These aberrant activities were attenuated following systemic NPD1 administration, with concomitant hippocampal dendritic spine protection. Moreover, NPD1 treatment led to a reduction in spontaneous recurrent seizures. Conclusions Our results indicate that NPD1 displays neuroprotective bioactivity on the hippocampal neuronal network ensemble that mediates aberrant circuit activity during epileptogenesis. Insight into the molecular signaling mediated by neuroprotective bioactivity of NPD1 on neuronal network dysfunction may contribute to the development of anti-epileptogenic therapeutic strategies. PMID:25617763

  4. Intraneuronal APP and extracellular Aβ independently cause dendritic spine pathology in transgenic mouse models of Alzheimer's disease.

    PubMed

    Zou, Chengyu; Montagna, Elena; Shi, Yuan; Peters, Finn; Blazquez-Llorca, Lidia; Shi, Song; Filser, Severin; Dorostkar, Mario M; Herms, Jochen

    2015-06-01

    Alzheimer's disease (AD) is thought to be caused by accumulation of amyloid-β protein (Aβ), which is a cleavage product of amyloid precursor protein (APP). Transgenic mice overexpressing APP have been used to recapitulate amyloid-β pathology. Among them, APP23 and APPswe/PS1deltaE9 (deltaE9) mice are extensively studied. APP23 mice express APP with Swedish mutation and develop amyloid plaques late in their life, while cognitive deficits are observed in young age. In contrast, deltaE9 mice with mutant APP and mutant presenilin-1 develop amyloid plaques early but show typical cognitive deficits in old age. To unveil the reasons for different progressions of cognitive decline in these commonly used mouse models, we analyzed the number and turnover of dendritic spines as important structural correlates for learning and memory. Chronic in vivo two-photon imaging in apical tufts of layer V pyramidal neurons revealed a decreased spine density in 4-5-month-old APP23 mice. In age-matched deltaE9 mice, in contrast, spine loss was only observed on cortical dendrites that were in close proximity to amyloid plaques. In both cases, the reduced spine density was caused by decreased spine formation. Interestingly, the patterns of alterations in spine morphology differed between these two transgenic mouse models. Moreover, in APP23 mice, APP was found to accumulate intracellularly and its content was inversely correlated with the absolute spine density and the relative number of mushroom spines. Collectively, our results suggest that different pathological mechanisms, namely an intracellular accumulation of APP or extracellular amyloid plaques, may lead to spine abnormalities in young adult APP23 and deltaE9 mice, respectively. These distinct features, which may represent very different mechanisms of synaptic failure in AD, have to be taken into consideration when translating results from animal studies to the human disease.

  5. Altered sensory experience exacerbates stable dendritic spine and synapse loss in a mouse model of Huntington's disease.

    PubMed

    Murmu, Reena Prity; Li, Wen; Szepesi, Zsuzsanna; Li, Jia-Yi

    2015-01-07

    A key question in Huntington's disease (HD) is what underlies the early cognitive deficits that precede the motor symptoms and the characteristic neuronal death observed in HD. The mechanisms underlying cognitive symptoms in HD remain unknown. Postmortem HD brain and animal model studies demonstrate pathologies in dendritic spines and abnormal synaptic plasticity before motor symptoms and neurodegeneration. Experience-dependent synaptic plasticity caused by mechanisms such as LTP or novel sensory experience potentiates synaptic strength, enhances new dendritic spine formation and stabilization, and may contribute to normal cognitive processes, such as learning and memory. We have previously reported that under baseline conditions (without any sensory manipulation) neuronal circuitry in HD (R6/2 mouse model) was highly unstable, which led to a progressive loss of persistent spines in these mice, and that mutant huntingtin was directly involved in the process. Here, we investigated whether pathological processes of HD interfere with the normal experience-dependent plasticity of dendritic spines in the R6/2 model. Six weeks of two-photon in vivo imaging before and after whisker trimming revealed that sensory deprivation exacerbates loss of persistent-type, stable spines in R6/2 mice compared with wild-type littermates. In addition, sensory deprivation leads to impaired transformation of newly generated spines into persistent spines in R6/2 mice. As a consequence, reduced synaptic density and decreased PSD-95 protein levels are evident in their barrel cortical neurons. These data suggest that mutant huntingtin is implicated in maladaptive synaptic plasticity, which could be one of the plausible mechanisms underlying early cognitive deficits in HD. Copyright © 2015 the authors 0270-6474/15/350287-12$15.00/0.

  6. Cocaine alters dendritic spine density in cortical and subcortical brain regions of the postpartum and virgin female rat.

    PubMed

    Frankfurt, Maya; Salas-Ramirez, Kaliris; Friedman, Eitan; Luine, Victoria

    2011-09-01

    Cocaine use during pregnancy induces profound neural and behavioral deficits in both mother and offspring. The present study was designed to compare the effects of cocaine exposure on spine density of postpartum and virgin female rat brains. Timed, pregnant, primiparous rats were injected with either cocaine (30 mg/kg) or saline, once daily, from gestational day 8 to 20. Twenty-four hours after giving birth, dam brains were processed for Golgi-impregnation. Virgin females were also injected with the same dose of cocaine or saline for 12 days and sacrificed 24 h after the last injection for comparison. Pregnant rats had significantly greater spine density in the medial amygdala (MeA) and medial preoptic area (MPOA) and lower spine density in CA1 than virgin females independent of cocaine treatment. Cocaine significantly increased dendritic spine density on the apical branch of pyramidal cells in the prefrontal cortex (PFC, 15%), both apical (13%) and basal (14.8%) branches of CA1 and cells in the MeA (28%) of pregnant rats. In the MPOA, cocaine administration resulted in a decrease in dendritic spine density (14%) in pregnant rats. In virgin females, cocaine had fewer effects but did increase dendritic spine density on both branches of CA1 neurons and in the MeA. The present study is the first to demonstrate that spine density differs between pregnant and virgin females and that pregnancy makes the brain more vulnerable to cocaine, which has important clinical implications. Copyright © 2011 Wiley-Liss, Inc.

  7. Reelin supplementation enhances cognitive ability, synaptic plasticity, and dendritic spine density

    PubMed Central

    Rogers, Justin T.; Rusiana, Ian; Trotter, Justin; Zhao, Lisa; Donaldson, Erika; Pak, Daniel T.S.; Babus, Lenard W.; Peters, Melinda; Banko, Jessica L.; Chavis, Pascale; Rebeck, G. William; Hoe, Hyang-Sook; Weeber, Edwin J.

    2011-01-01

    Apolipoprotein receptors belong to an evolutionarily conserved surface receptor family that has intimate roles in the modulation of synaptic plasticity and is necessary for proper hippocampal-dependent memory formation. The known lipoprotein receptor ligand Reelin is important for normal synaptic plasticity, dendritic morphology, and cognitive function; however, the in vivo effect of enhanced Reelin signaling on cognitive function and synaptic plasticity in wild-type mice is unknown. The present studies test the hypothesis that in vivo enhancement of Reelin signaling can alter synaptic plasticity and ultimately influence processes of learning and memory. Purified recombinant Reelin was injected bilaterally into the ventricles of wild-type mice. We demonstrate that a single in vivo injection of Reelin increased activation of adaptor protein Disabled-1 and cAMP-response element binding protein after 15 min. These changes correlated with increased dendritic spine density, increased hippocampal CA1 long-term potentiation (LTP), and enhanced performance in associative and spatial learning and memory. The present study suggests that an acute elevation of in vivo Reelin can have long-term effects on synaptic function and cognitive ability in wild-type mice. PMID:21852430

  8. Calmodulin Activation by Calcium Transients in the Postsynaptic Density of Dendritic Spines

    PubMed Central

    Keller, Daniel X.; Franks, Kevin M.; Bartol, Thomas M.; Sejnowski, Terrence J.

    2008-01-01

    The entry of calcium into dendritic spines can trigger a sequence of biochemical reactions that begins with the activation of calmodulin (CaM) and ends with long-term changes to synaptic strengths. The degree of activation of CaM can depend on highly local elevations in the concentration of calcium and the duration of transient increases in calcium concentration. Accurate measurement of these local changes in calcium is difficult because the spaces are so small and the numbers of molecules are so low. We have therefore developed a Monte Carlo model of intracellular calcium dynamics within the spine that included calcium binding proteins, calcium transporters and ion channels activated by voltage and glutamate binding. The model reproduced optical recordings using calcium indicator dyes and showed that without the dye the free intracellular calcium concentration transient was much higher than predicted from the fluorescent signal. Excitatory postsynaptic potentials induced large, long-lasting calcium gradients across the postsynaptic density, which activated CaM. When glutamate was released at the synapse 10 ms before an action potential occurred, simulating activity patterns that strengthen hippocampal synapses, the calcium gradient and activation of CaM in the postsynaptic density were much greater than when the order was reversed, a condition that decreases synaptic strengths, suggesting a possible mechanism underlying the induction of long-term changes in synaptic strength. The spatial and temporal mechanisms for selectivity in CaM activation demonstrated here could be used in other signaling pathways. PMID:18446197

  9. Integration of multiscale dendritic spine structure and function data into systems biology models.

    PubMed

    Mancuso, James J; Cheng, Jie; Yin, Zheng; Gilliam, Jared C; Xia, Xiaofeng; Li, Xuping; Wong, Stephen T C

    2014-01-01

    Comprising 10(11) neurons with 10(14) synaptic connections the human brain is the ultimate systems biology puzzle. An increasing body of evidence highlights the observation that changes in brain function, both normal and pathological, consistently correlate with dynamic changes in neuronal anatomy. Anatomical changes occur on a full range of scales from the trafficking of individual proteins, to alterations in synaptic morphology both individually and on a systems level, to reductions in long distance connectivity and brain volume. The major sites of contact for synapsing neurons are dendritic spines, which provide an excellent metric for the number and strength of signaling connections between elements of functional neuronal circuits. A comprehensive model of anatomical changes and their functional consequences would be a holy grail for the field of systems neuroscience but its realization appears far on the horizon. Various imaging technologies have advanced to allow for multi-scale visualization of brain plasticity and pathology, but computational analysis of the big data sets involved forms the bottleneck toward the creation of multiscale models of brain structure and function. While a full accounting of techniques and progress toward a comprehensive model of brain anatomy and function is beyond the scope of this or any other single paper, this review serves to highlight the opportunities for analysis of neuronal spine anatomy and function provided by new imaging technologies and the high-throughput application of older technologies while surveying the strengths and weaknesses of currently available computational analytical tools and room for future improvement.

  10. High throughput, detailed, cell-specific neuroanatomy of dendritic spines using microinjection and confocal microscopy

    PubMed Central

    Dumitriu, Dani; Rodriguez, Alfredo; Morrison, John H.

    2012-01-01

    Morphological features such as size, shape and density of dendritic spines have been shown to reflect important synaptic functional attributes and potential for plasticity. Here we describe in detail a protocol for obtaining detailed morphometric analysis of spines using microinjection of fluorescent dyes, high resolution confocal microscopy, deconvolution and image analysis using NeuronStudio. Recent technical advancements include better preservation of tissue resulting in prolonged ability to microinject, and algorithmic improvements that compensate for the residual Z-smear inherent in all optical imaging. Confocal imaging parameters were probed systematically for the identification of both optimal resolution as well as highest efficiency. When combined, our methods yield size and density measurements comparable to serial section transmission electron microscopy in a fraction of the time. An experiment containing 3 experimental groups with 8 subjects in each can take as little as one month if optimized for speed, or approximately 4 to 5 months if the highest resolution and morphometric detail is sought. PMID:21886104

  11. Heterogeneous Nuclear Ribonucleoprotein K Interacts with Abi-1 at Postsynaptic Sites and Modulates Dendritic Spine Morphology

    PubMed Central

    Proepper, Christian; Steinestel, Konrad; Schmeisser, Michael J.; Heinrich, Jutta; Steinestel, Julie; Bockmann, Juergen; Liebau, Stefan; Boeckers, Tobias M.

    2011-01-01

    Background Abelson-interacting protein 1 (Abi-1) plays an important role for dendritic branching and synapse formation in the central nervous system. It is localized at the postsynaptic density (PSD) and rapidly translocates to the nucleus upon synaptic stimulation. At PSDs Abi-1 is in a complex with several other proteins including WASP/WAVE or cortactin thereby regulating the actin cytoskeleton via the Arp 2/3 complex. Principal Findings We identified heterogeneous nuclear ribonucleoprotein K (hnRNPK), a 65 kDa ssDNA/RNA-binding-protein that is involved in multiple intracellular signaling cascades, as a binding partner of Abi-1 at postsynaptic sites. The interaction with the Abi-1 SH3 domain is mediated by the hnRNPK-interaction (KI) domain. We further show that during brain development, hnRNPK expression becomes more and more restricted to granule cells of the cerebellum and hippocampal neurons where it localizes in the cell nucleus as well as in the spine/dendritic compartment. The downregulation of hnRNPK in cultured hippocampal neurons by RNAi results in an enlarged dendritic tree and a significant increase in filopodia formation. This is accompanied by a decrease in the number of mature synapses. Both effects therefore mimic the neuronal morphology after downregulation of Abi-1 mRNA in neurons. Conclusions Our findings demonstrate a novel interplay between hnRNPK and Abi-1 in the nucleus and at synaptic sites and show obvious similarities regarding both protein knockdown phenotypes. This indicates that hnRNPK and Abi-1 act synergistic in a multiprotein complex that regulates the crucial balance between filopodia formation and synaptic maturation in neurons. PMID:22102872

  12. Heterogeneous nuclear ribonucleoprotein k interacts with Abi-1 at postsynaptic sites and modulates dendritic spine morphology.

    PubMed

    Proepper, Christian; Steinestel, Konrad; Schmeisser, Michael J; Heinrich, Jutta; Steinestel, Julie; Bockmann, Juergen; Liebau, Stefan; Boeckers, Tobias M

    2011-01-01

    Abelson-interacting protein 1 (Abi-1) plays an important role for dendritic branching and synapse formation in the central nervous system. It is localized at the postsynaptic density (PSD) and rapidly translocates to the nucleus upon synaptic stimulation. At PSDs Abi-1 is in a complex with several other proteins including WASP/WAVE or cortactin thereby regulating the actin cytoskeleton via the Arp 2/3 complex. We identified heterogeneous nuclear ribonucleoprotein K (hnRNPK), a 65 kDa ssDNA/RNA-binding-protein that is involved in multiple intracellular signaling cascades, as a binding partner of Abi-1 at postsynaptic sites. The interaction with the Abi-1 SH3 domain is mediated by the hnRNPK-interaction (KI) domain. We further show that during brain development, hnRNPK expression becomes more and more restricted to granule cells of the cerebellum and hippocampal neurons where it localizes in the cell nucleus as well as in the spine/dendritic compartment. The downregulation of hnRNPK in cultured hippocampal neurons by RNAi results in an enlarged dendritic tree and a significant increase in filopodia formation. This is accompanied by a decrease in the number of mature synapses. Both effects therefore mimic the neuronal morphology after downregulation of Abi-1 mRNA in neurons. Our findings demonstrate a novel interplay between hnRNPK and Abi-1 in the nucleus and at synaptic sites and show obvious similarities regarding both protein knockdown phenotypes. This indicates that hnRNPK and Abi-1 act synergistic in a multiprotein complex that regulates the crucial balance between filopodia formation and synaptic maturation in neurons.

  13. Voltage-sensitive dye recording from axons, dendrites and dendritic spines of individual neurons in brain slices.

    PubMed

    Popovic, Marko; Gao, Xin; Zecevic, Dejan

    2012-11-29

    phototoxic effects (4, 6, 12, 13). At present, we take advantage of the superb brightness and stability of a laser light source at near-optimal wavelength to maximize the sensitivity of the V(m)-imaging technique. The current sensitivity permits multiple site optical recordings of V(m) transients from all parts of a neuron, including axons and axon collaterals, terminal dendritic branches, and individual dendritic spines. The acquired information on signal interactions can be analyzed quantitatively as well as directly visualized in the form of a movie.

  14. The Endosome Localized Arf-GAP AGAP1 Modulates Dendritic Spine Morphology Downstream of the Neurodevelopmental Disorder Factor Dysbindin

    PubMed Central

    Arnold, Miranda; Cross, Rebecca; Singleton, Kaela S.; Zlatic, Stephanie; Chapleau, Christopher; Mullin, Ariana P.; Rolle, Isaiah; Moore, Carlene C.; Theibert, Anne; Pozzo-Miller, Lucas; Faundez, Victor; Larimore, Jennifer

    2016-01-01

    AGAP1 is an Arf1 GTPase activating protein that interacts with the vesicle-associated protein complexes adaptor protein 3 (AP-3) and Biogenesis of Lysosome Related Organelles Complex-1 (BLOC-1). Overexpression of AGAP1 in non-neuronal cells results in an accumulation of endosomal cargoes, which suggests a role in endosome-dependent traffic. In addition, AGAP1 is a candidate susceptibility gene for two neurodevelopmental disorders, autism spectrum disorder (ASD) and schizophrenia (SZ); yet its localization and function in neurons have not been described. Here, we describe that AGAP1 localizes to axons, dendrites, dendritic spines and synapses, colocalizing preferentially with markers of early and recycling endosomes. Functional studies reveal overexpression and down-regulation of AGAP1 affects both neuronal endosomal trafficking and dendritic spine morphology, supporting a role for AGAP1 in the recycling endosomal trafficking involved in their morphogenesis. Finally, we determined the sensitivity of AGAP1 expression to mutations in the DTNBP1 gene, which is associated with neurodevelopmental disorder, and found that AGAP1 mRNA and protein levels are selectively reduced in the null allele of the mouse ortholog of DTNBP1. We postulate that endosomal trafficking contributes to the pathogenesis of neurodevelopmental disorders affecting dendritic spine morphology, and thus excitatory synapse structure and function. PMID:27713690

  15. Chronic intermittent ethanol exposure and withdrawal leads to adaptations in nucleus accumbens core postsynaptic density proteome and dendritic spines.

    PubMed

    Uys, Joachim D; McGuier, Natalie S; Gass, Justin T; Griffin, William C; Ball, Lauren E; Mulholland, Patrick J

    2016-05-01

    Alcohol use disorder is a chronic relapsing brain disease characterized by the loss of ability to control alcohol (ethanol) intake despite knowledge of detrimental health or personal consequences. Clinical and pre-clinical models provide strong evidence for chronic ethanol-associated alterations in glutamatergic signaling and impaired synaptic plasticity in the nucleus accumbens (NAc). However, the neural mechanisms that contribute to aberrant glutamatergic signaling in ethanol-dependent individuals in this critical brain structure remain unknown. Using an unbiased proteomic approach, we investigated the effects of chronic intermittent ethanol (CIE) exposure on neuroadaptations in postsynaptic density (PSD)-enriched proteins in the NAc of ethanol-dependent mice. Compared with controls, CIE exposure significantly changed expression levels of 50 proteins in the PSD-enriched fraction. Systems biology and functional annotation analyses demonstrated that the dysregulated proteins are expressed at tetrapartite synapses and critically regulate cellular morphology. To confirm this latter finding, the density and morphology of dendritic spines were examined in the NAc core of ethanol-dependent mice. We found that CIE exposure and withdrawal differentially altered dendrite diameter and dendritic spine density and morphology. Through the use of quantitative proteomics and functional annotation, these series of experiments demonstrate that ethanol dependence produces neuroadaptations in proteins that modify dendritic spine morphology. In addition, these studies identified novel PSD-related proteins that contribute to the neurobiological mechanisms of ethanol dependence that drive maladaptive structural plasticity of NAc neurons. © 2015 Society for the Study of Addiction.

  16. Marginal Iodine Deficiency Affects Dendritic Spine Development by Disturbing the Function of Rac1 Signaling Pathway on Cytoskeleton.

    PubMed

    Min, Hui; Dong, Jing; Wang, Yi; Wang, Yuan; Yu, Ye; Shan, Zhongyan; Xi, Qi; Teng, Weiping; Chen, Jie

    2017-01-01

    Iodine deficiency (ID)-induced thyroid hormone (TH) insufficient during development leads to impairments of brain function, such as learning and memory. Marginal ID has been defined as subtle insufficiency of TH, characterized as low thyroxine (T4) levels, whether marginal ID potentially had adverse effects on the development of hippocampus and the underlying mechanisms remain unclear. Thus, in the present study, we established Wistar rat models with ID diet during pregnancy and lactation. The effects of marginal ID on long-term potentiation (LTP) were investigated in the hippocampal CA1 region. To study the development of dendritic spines in pyramidal cells, Golgi-Cox staining was conducted on postnatal day (PN) 7, PN14, PN21, and PN28. The activation of Rac1 signaling pathway, which is essential for dendritic spine development by regulating actin cytoskeleton, was also investigated. Our results showed that marginal ID slightly reduced the field-excitatory postsynaptic potential (f-EPSP) slope and the population spike (PS) amplitude. Besides, the density of dendritic spines during the critical period of rat postnatal development was mildly decreased, and we found no significant change of spine morphology in marginal ID group. We also observed decreased activation of the Rac1 signaling pathway in pups subjected to maternal marginal ID. Our study may support the hypothesis that decreased T4 induced by marginal ID results in slight impairments of LTP and leads to mild damage of dendritic spine development, which may be due to abnormal regulation of Rac1 signaling pathway on cytoskeleton.

  17. ADP-ribosylation Factor 6 (ARF6) Bidirectionally Regulates Dendritic Spine Formation Depending on Neuronal Maturation and Activity*

    PubMed Central

    Kim, Yoonju; Lee, Sang-Eun; Park, Joohyun; Kim, Minhyung; Lee, Boyoon; Hwang, Daehee; Chang, Sunghoe

    2015-01-01

    Recent studies have reported conflicting results regarding the role of ARF6 in dendritic spine development, but no clear answer for the controversy has been suggested. We found that ADP-ribosylation factor 6 (ARF6) either positively or negatively regulates dendritic spine formation depending on neuronal maturation and activity. ARF6 activation increased the spine formation in developing neurons, whereas it decreased spine density in mature neurons. Genome-wide microarray analysis revealed that ARF6 activation in each stage leads to opposite patterns of expression of a subset of genes that are involved in neuronal morphology. ARF6-mediated Rac1 activation via the phospholipase D pathway is the coincident factor in both stages, but the antagonistic RhoA pathway becomes involved in the mature stage. Furthermore, blocking neuronal activity in developing neurons using tetrodotoxin or enhancing the activity in mature neurons using picrotoxin or chemical long term potentiation reversed the effect of ARF6 on each stage. Thus, activity-dependent dynamic changes in ARF6-mediated spine structures may play a role in structural plasticity of mature neurons. PMID:25605715

  18. 3D dendritic α-Fe2O3 nano-architectures: Synthesis and its application on electrochemical non-enzymatic H2O2 sensing

    NASA Astrophysics Data System (ADS)

    Majumder, S.; Saha, B.; Dey, S.; Bagani, K.; Roy, M. K.; Jana, S. K.; Kumar, S.; Banerjee, S.

    2015-06-01

    In this manuscript we have successfully synthesized a large scale 3D dendritic α-Fe2O3 hierarchical structure via a hydrothermal reaction. The crystallinity, composition, purity, morphology of the synthesized α-Fe2O3 are characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FESEM), energy dispersive X-ray spectroscopic (EDS). FESEM image reveals that the individual α-Fe2O3 dendrite consists of a long central trunk with secondary and tertiary branches. For electrochemical H2O2 sensing we have carried out cyclic voltammetry (CV), amperometric i-t measurement. It has been found that the current density vs. H2O2 concentration calibration curve is linear in nature. The present study reveals that the dendritic α-Fe2O3 hierarchical structure exhibits very sensitive electrochemical sensing capability towards H2O2 reduction.

  19. RuBi-Glutamate: Two-Photon and Visible-Light Photoactivation of Neurons and Dendritic spines.

    PubMed

    Fino, Elodie; Araya, Roberto; Peterka, Darcy S; Salierno, Marcelo; Etchenique, Roberto; Yuste, Rafael

    2009-01-01

    We describe neurobiological applications of RuBi-Glutamate, a novel caged-glutamate compound based on ruthenium photochemistry. RuBi-Glutamate can be excited with visible wavelengths and releases glutamate after one- or two-photon excitation. It has high quantum efficiency and can be used at low concentrations, partly avoiding the blockade of GABAergic transmission present with other caged compounds. Two-photon uncaging of RuBi-Glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics. With laser beam multiplexing, two-photon RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution. RuBi-Glutamate therefore enables the photoactivation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single cell, or even single spine, precision.

  20. RuBi-Glutamate: Two-Photon and Visible-Light Photoactivation of Neurons and Dendritic spines

    PubMed Central

    Fino, Elodie; Araya, Roberto; Peterka, Darcy S.; Salierno, Marcelo; Etchenique, Roberto; Yuste, Rafael

    2009-01-01

    We describe neurobiological applications of RuBi-Glutamate, a novel caged-glutamate compound based on ruthenium photochemistry. RuBi-Glutamate can be excited with visible wavelengths and releases glutamate after one- or two-photon excitation. It has high quantum efficiency and can be used at low concentrations, partly avoiding the blockade of GABAergic transmission present with other caged compounds. Two-photon uncaging of RuBi-Glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics. With laser beam multiplexing, two-photon RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution. RuBi-Glutamate therefore enables the photoactivation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single cell, or even single spine, precision. PMID:19506708

  1. Dysfunctional epileptic neuronal circuits and dysmorphic dendritic spines are mitigated by platelet-activating factor receptor antagonism

    PubMed Central

    Musto, Alberto E.; Rosencrans, Robert F.; Walker, Chelsey P.; Bhattacharjee, Surjyadipta; Raulji, Chittalsinh M.; Belayev, Ludmila; Fang, Zhide; Gordon, William C.; Bazan, Nicolas G.

    2016-01-01

    Temporal lobe epilepsy or limbic epilepsy lacks effective therapies due to a void in understanding the cellular and molecular mechanisms that set in motion aberrant neuronal network formations during the course of limbic epileptogenesis (LE). Here we show in in vivo rodent models of LE that the phospholipid mediator platelet-activating factor (PAF) increases in LE and that PAF receptor (PAF-r) ablation mitigates its progression. Synthetic PAF-r antagonists, when administered intraperitoneally in LE, re-establish hippocampal dendritic spine density and prevent formation of dysmorphic dendritic spines. Concomitantly, hippocampal interictal spikes, aberrant oscillations, and neuronal hyper-excitability, evaluated 15–16 weeks after LE using multi-array silicon probe electrodes implanted in the dorsal hippocampus, are reduced in PAF-r antagonist-treated mice. We suggest that over-activation of PAF-r signaling induces aberrant neuronal plasticity in LE and leads to chronic dysfunctional neuronal circuitry that mediates epilepsy. PMID:27444269

  2. The accuracy of a 2D and 3D dendritic tip scaling parameter in predicting the columnar to equiaxed transition (CET)

    NASA Astrophysics Data System (ADS)

    Seredyński, M.; Rebow, M.; Banaszek, J.

    2016-09-01

    The dendrite tip kinetics model accuracy relies on the reliability of the stability constant used, which is usually experimentally determined for 3D situations and applied to 2D models. The paper reports authors' attempts to cure the situation by deriving 2D dendritic tip scaling parameter for aluminium-based alloy: Al-4wt%Cu. The obtained parameter is then incorporated into the KGT dendritic growth model in order to compare it with the original 3D KGT counterpart and to derive two-dimensional and three-dimensional versions of the modified Hunt's analytical model for the columnar-to-equiaxed transition (CET). The conclusions drawn from the above analysis are further confirmed through numerical calculations of the two cases of Al-4wt%Cu metallic alloy solidification using the front tracking technique. Results, including the porous zone-under-cooled liquid front position, the calculated solutal under-cooling and a new predictor of the relative tendency to form an equiaxed zone, are shown, compared and discussed two numerical cases. The necessity to calculate sufficiently precise values of the tip scaling parameter in 2D and 3D is stressed.

  3. Endothelial Nitric Oxide Synthase Is Present in Dendritic Spines of Neurons in Primary Cultures.

    PubMed

    Caviedes, Ariel; Varas-Godoy, Manuel; Lafourcade, Carlos; Sandoval, Soledad; Bravo-Alegria, Javiera; Kaehne, Thilo; Massmann, Angela; Figueroa, Jorge P; Nualart, Francisco; Wyneken, Ursula

    2017-01-01

    Nitric oxide exerts important regulatory functions in various brain processes. Its synthesis in neurons has been most commonly ascribed to the neuronal nitric oxide synthase (nNOS) isoform. However, the endothelial isoform (eNOS), which is significantly associated with caveolae in different cell types, has been implicated in synaptic plasticity and is enriched in the dendrites of CA1 hippocampal neurons. Using high resolution microscopy and co-distribution analysis of eNOS with synaptic and raft proteins, we now show for the first time in primary cortical and hippocampal neuronal cultures, virtually devoid of endothelial cells, that eNOS is present in neurons and is localized in dendritic spines. Moreover, eNOS is present in a postsynaptic density-enriched biochemical fraction isolated from these neuronal cultures. In addition, qPCR analysis reveals that both the nNOS as well as the eNOS transcripts are present in neuronal cultures. Moreover, eNOS inhibition in cortical cells has a negative impact on cell survival after excitotoxic stimulation with N-methyl-D-aspartate (NMDA). Consistent with previous results that indicated nitric oxide production in response to the neurotrophin BDNF, we could detect eNOS in immunoprecipitates of the BDNF receptor TrkB while nNOS could not be detected. Taken together, our results show that eNOS is located at excitatory synapses where it could represent a source for NO production and thus, the contribution of eNOS-derived nitric oxide to the regulation of neuronal survival and function deserves further investigations.

  4. Indeterminate Dendritic Cell Tumor in Thoracic Spine: A Case Report and Review of Literature.

    PubMed

    Tan, Sze Kiat; Chieng, Lee Onn; Madhavan, Karthik; Rosenberg, Andrew; Cote, Ian

    2017-07-26

    Indeterminate dendritic cell tumor (IDCT) is an extremely rare hematological disorder with poorly understood pathogenesis. Occasionally encountered by hematologists, unusual presentations of IDCT have never been reported in the spine literature. The authors report a case of a 51-year-old man who presented with progressively worsening axial thoracic back pain radiating to his sides for three months. MRI revealed a large 3-cm enhancing mass at the T9 vertebral body with an exophytic component causing significant canal stenosis. Initial percutaneous biopsy revealed histiocytic sarcoma. The patient underwent exploratory throracotomy and en-bloc resection of the lesion with T8-10 fusion. Interestingly, the final pathology results revealed IDCT with fibrosis. IDCT immunostaining was partially positive for Langerhans cell marker (positive for S100 and CD1a, but lacked Birbeck granules and Langerin stain) and partially for blastic plasmacytoid dendritic cell neoplasm. In addition, it was positive for CD45, CD68 and CD163. Lymphadenopathy is absent in this patient. Although first reported in the 1980s, IDCT has been omitted from most classifications due to its rarity. Rezk et al. (2008), reported 5 cases of IDCT which is usually restricted to the skin and lymph nodes and carried a good prognosis. Hematologists have debated the cell of origin; it is believed to be comprised of pre-Langerhans cells, as Birbeck granules are acquired after migration to the epidermis. As for now, IDCT remains of indeterminate origin. We report the first case of spinal IDCT, and familiarity with the histological features are warranted to ensure accurate diagnosis and appropriate treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Endothelial Nitric Oxide Synthase Is Present in Dendritic Spines of Neurons in Primary Cultures

    PubMed Central

    Caviedes, Ariel; Varas-Godoy, Manuel; Lafourcade, Carlos; Sandoval, Soledad; Bravo-Alegria, Javiera; Kaehne, Thilo; Massmann, Angela; Figueroa, Jorge P.; Nualart, Francisco; Wyneken, Ursula

    2017-01-01

    Nitric oxide exerts important regulatory functions in various brain processes. Its synthesis in neurons has been most commonly ascribed to the neuronal nitric oxide synthase (nNOS) isoform. However, the endothelial isoform (eNOS), which is significantly associated with caveolae in different cell types, has been implicated in synaptic plasticity and is enriched in the dendrites of CA1 hippocampal neurons. Using high resolution microscopy and co-distribution analysis of eNOS with synaptic and raft proteins, we now show for the first time in primary cortical and hippocampal neuronal cultures, virtually devoid of endothelial cells, that eNOS is present in neurons and is localized in dendritic spines. Moreover, eNOS is present in a postsynaptic density-enriched biochemical fraction isolated from these neuronal cultures. In addition, qPCR analysis reveals that both the nNOS as well as the eNOS transcripts are present in neuronal cultures. Moreover, eNOS inhibition in cortical cells has a negative impact on cell survival after excitotoxic stimulation with N-methyl-D-aspartate (NMDA). Consistent with previous results that indicated nitric oxide production in response to the neurotrophin BDNF, we could detect eNOS in immunoprecipitates of the BDNF receptor TrkB while nNOS could not be detected. Taken together, our results show that eNOS is located at excitatory synapses where it could represent a source for NO production and thus, the contribution of eNOS-derived nitric oxide to the regulation of neuronal survival and function deserves further investigations. PMID:28725180

  6. Estrogen-induced dendritic spine elimination on female rat ventromedial hypothalamic neurons that project to the periaqueductal gray.

    PubMed

    Calizo, Lyngine H; Flanagan-Cato, Loretta M

    2002-06-03

    Neurons of the ventromedial hypothalamic nucleus (VMH) that project to the periaqueductal gray (PAG) form a crucial segment of the motor pathway that produces the lordosis posture, the hallmark of female rat sexual behavior. One suggested mechanism through which estrogen facilitates lordosis is by remodeling synaptic connectivity within the VMH. For instance, estrogen alters VMH dendritic spine density. Little is known, however, about the local VMH microcircuitry governing lordosis nor how estrogen alters synaptic connectivity within this local circuit to facilitate sexual behavior. The goal of this study was to define better the neuron types within the VMH microcircuitry and to examine whether estrogen alters synaptic connectivity, as measured by dendritic spine density, on VMH projection neurons. A retrograde tracer was injected into the PAG of ovariectomized rats treated with vehicle or estradiol. Retrogradely labeled VMH neurons were filled with Lucifer yellow, then immunostained for estrogen receptor-alpha (ER alpha). VMH neurons that project to the PAG had more dendrites than functionally unidentified neurons. Additionally, VMH projection neurons could be subdivided into those located within the cluster of ER alpha-containing neurons and those medial to the cluster. Estrogen decreased spine density by 57% on the long primary dendrites of VMH projection neurons located within the ER alpha cluster but not on projection neurons medial to the cluster. Only 4% of the VMH projection neurons expressed ER alpha. These results suggest that estrogen may facilitate sexual behavior by decreasing spines selectively, via an indirect mechanism, on a subset of VMH neurons that project to the PAG. Copyright 2002 Wiley-Liss, Inc.

  7. βIII Spectrin Is Necessary for Formation of the Constricted Neck of Dendritic Spines and Regulation of Synaptic Activity in Neurons.

    PubMed

    Efimova, Nadia; Korobova, Farida; Stankewich, Michael C; Moberly, Andrew H; Stolz, Donna B; Wang, Junling; Kashina, Anna; Ma, Minghong; Svitkina, Tatyana

    2017-07-05

    Dendritic spines are postsynaptic structures in neurons often having a mushroom-like shape. Physiological significance and cytoskeletal mechanisms that maintain this shape are poorly understood. The spectrin-based membrane skeleton maintains the biconcave shape of erythrocytes, but whether spectrins also determine the shape of nonerythroid cells is less clear. We show that βIII spectrin in hippocampal and cortical neurons from rodent embryos of both sexes is distributed throughout the somatodendritic compartment but is particularly enriched in the neck and base of dendritic spines and largely absent from spine heads. Electron microscopy revealed that βIII spectrin forms a detergent-resistant cytoskeletal network at these sites. Knockdown of βIII spectrin results in a significant decrease in the density of dendritic spines. Surprisingly, the density of presynaptic terminals is not affected by βIII spectrin knockdown. However, instead of making normal spiny synapses, the presynaptic structures in βIII spectrin-depleted neurons make shaft synapses that exhibit increased amplitudes of miniature EPSCs indicative of excessive postsynaptic excitation. Thus, βIII spectrin is necessary for formation of the constricted shape of the spine neck, which in turn controls communication between the synapse and the parent dendrite to prevent excessive excitation. Notably, mutations of SPTNB2 encoding βIII spectrin are associated with neurodegenerative syndromes, spinocerebellar ataxia Type 5, and spectrin-associated autosomal recessive cerebellar ataxia Type 1, but molecular mechanisms linking βIII spectrin functions to neuronal pathologies remain unresolved. Our data suggest that spinocerebellar ataxia Type 5 and spectrin-associated autosomal recessive cerebellar ataxia Type 1 pathology likely arises from poorly controlled synaptic activity that leads to excitotoxicity and neurodegeneration.SIGNIFICANCE STATEMENT Dendritic spines are small protrusions from neuronal

  8. GSK-3β Overexpression Alters the Dendritic Spines of Developmentally Generated Granule Neurons in the Mouse Hippocampal Dentate Gyrus

    PubMed Central

    Pallas-Bazarra, Noemí; Kastanauskaite, Asta; Avila, Jesús; DeFelipe, Javier; Llorens-Martín, María

    2017-01-01

    The dentate gyrus (DG) plays a crucial role in hippocampal-related memory. The most abundant cellular type in the DG, namely granule neurons, are developmentally generated around postnatal day P6 in mice. Moreover, a unique feature of the DG is the occurrence of adult hippocampal neurogenesis, a process that gives rise to newborn granule neurons throughout life. Adult-born and developmentally generated granule neurons share some maturational aspects but differ in others, such as in their positioning within the granule cell layer. Adult hippocampal neurogenesis encompasses a series of plastic changes that modify the function of the hippocampal trisynaptic network. In this regard, it is known that glycogen synthase kinase 3β (GSK-3β) regulates both synaptic plasticity and memory. By using a transgenic mouse overexpressing GSK-3β in hippocampal neurons, we previously demonstrated that the overexpression of this kinase has deleterious effects on the maturation of newborn granule neurons. In the present study, we addressed the effects of GSK-3β overexpression on the morphology and number of dendritic spines of developmentally generated granule neurons. To this end, we performed intracellular injections of Lucifer Yellow in developmentally generated granule neurons of wild-type and GSK-3β-overexpressing mice and analyzed the number and morphologies of dendritic spines (namely, stubby, thin and mushroom). GSK-3β overexpression led to a general reduction in the number of dendritic spines. In addition, it caused a slight reduction in the percentage, head diameter and length of thin spines, whereas the head diameter of mushroom spines was increased. PMID:28344548

  9. Prolonged ampakine exposure prunes dendritic spines and increases presynaptic release probability for enhanced long-term potentiation in the hippocampus.

    PubMed

    Chang, Philip K-Y; Prenosil, George A; Verbich, David; Gill, Raminder; McKinney, R Anne

    2014-09-01

    CX 546, an allosteric positive modulator of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type ionotropic glutamate receptors (AMPARs), belongs to a drug class called ampakines. These compounds have been shown to enhance long-term potentiation (LTP), a cellular model of learning and memory, and improve animal learning task performance, and have augmented cognition in neurodegenerative patients. However, the chronic effect of CX546 on synaptic structures has not been examined. The structure and integrity of dendritic spines are thought to play a role in learning and memory, and their abnormalities have been implicated in cognitive disorders. In addition, their structural plasticity has been shown to be important for cognitive function, such that dendritic spine remodeling has been proposed as the morphological correlate for LTP. Here, we tested the effect of CX546 on dendritic spine remodeling following long-term treatment. We found that, with prolonged CX546 treatment, organotypic hippocampal slice cultures showed a significant reduction in CA3-CA1 excitatory synapse and spine density. Electrophysiological approaches revealed that the CA3-CA1 circuitry compensates for this synapse loss by increasing synaptic efficacy through enhancement of presynaptic release probability. CX546-treated slices showed prolonged and enhanced potentiation upon LTP induction. Furthermore, structural plasticity, namely spine head enlargement, was also more pronounced after CX546 treatment. Our results suggest a concordance of functional and structural changes that is enhanced with prolonged CX546 exposure. Thus, the improved cognitive ability of patients receiving ampakine treatment may result from the priming of synapses through increases in the structural plasticity and functional reliability of hippocampal synapses.

  10. Repeated exposure to ketamine-xylazine during early development impairs motor learning-dependent dendritic spine plasticity in adulthood.

    PubMed

    Huang, Lianyan; Yang, Guang

    2015-04-01

    Recent studies in rodents suggest that repeated and prolonged anesthetic exposure at early stages of development leads to cognitive and behavioral impairments later in life. However, the underlying mechanism remains unknown. In this study, we tested whether exposure to general anesthesia during early development will disrupt the maturation of synaptic circuits and compromise learning-related synaptic plasticity later in life. Mice received ketamine-xylazine (20/3 mg/kg) anesthesia for one or three times, starting at either early (postnatal day 14 [P14]) or late (P21) stages of development (n = 105). Control mice received saline injections (n = 34). At P30, mice were subjected to rotarod motor training and fear conditioning. Motor learning-induced synaptic remodeling was examined in vivo by repeatedly imaging fluorescently labeled postsynaptic dendritic spines in the primary motor cortex before and after training using two-photon microscopy. Three exposures to ketamine-xylazine anesthesia between P14 and P18 impair the animals' motor learning and learning-dependent dendritic spine plasticity (new spine formation, 8.4 ± 1.3% [mean ± SD] vs. 13.4 ± 1.8%, P = 0.002) without affecting fear memory and cell apoptosis. One exposure at P14 or three exposures between P21 and P25 has no effects on the animals' motor learning or spine plasticity. Finally, enriched motor experience ameliorates anesthesia-induced motor learning impairment and synaptic deficits. Our study demonstrates that repeated exposures to ketamine-xylazine during early development impair motor learning and learning-dependent dendritic spine plasticity later in life. The reduction in synaptic structural plasticity may underlie anesthesia-induced behavioral impairment.

  11. miR-132 Regulates Dendritic Spine Structure by Direct Targeting of Matrix Metalloproteinase 9 mRNA.

    PubMed

    Jasińska, Magdalena; Miłek, Jacek; Cymerman, Iwona A; Łęski, Szymon; Kaczmarek, Leszek; Dziembowska, Magdalena

    2016-09-01

    Mir-132 is a neuronal activity-regulated microRNA that controls the morphology of dendritic spines and neuronal transmission. Similar activities have recently been attributed to matrix metalloproteinase-9 (MMP-9), an extrasynaptic protease. In the present study, we provide evidence that miR-132 directly regulates MMP-9 mRNA in neurons to modulate synaptic plasticity. With the use of luciferase reporter system, we show that miR-132 binds to the 3'UTR of MMP-9 mRNA to regulate its expression in neurons. The overexpression of miR-132 in neurons reduces the level of endogenous MMP-9 protein secretion. In synaptoneurosomes, metabotropic glutamate receptor (mGluR)-induced signaling stimulates the dissociation of miR-132 from polyribosomal fractions and shifts it towards the messenger ribonucleoprotein (mRNP)-containing fraction. Furthermore, we demonstrate that the overexpression of miR-132 in the cultured hippocampal neurons from Fmr1 KO mice that have increased synaptic MMP-9 level provokes enlargement of the dendritic spine heads, a process previously implicated in enhanced synaptic plasticity. We propose that activity-dependent miR-132 regulates structural plasticity of dendritic spines through matrix metalloproteinase 9.

  12. Cortical synaptic and dendritic spine abnormalities in a presymptomatic TDP-43 model of amyotrophic lateral sclerosis

    PubMed Central

    Fogarty, Matthew J.; Klenowski, Paul M.; Lee, John D.; Drieberg-Thompson, Joy R.; Bartlett, Selena E.; Ngo, Shyuan T.; Hilliard, Massimo A.; Bellingham, Mark C.; Noakes, Peter G.

    2016-01-01

    Layer V pyramidal neurons (LVPNs) within the motor cortex integrate sensory cues and co-ordinate voluntary control of motor output. In amyotrophic lateral sclerosis (ALS) LVPNs and spinal motor neurons degenerate. The pathogenesis of neural degeneration is unknown in ALS; 10% of cases have a genetic cause, whereas 90% are sporadic, with most of the latter showing TDP-43 inclusions. Clinical and experimental evidence implicate excitotoxicity as a prime aetiological candidate. Using patch clamp and dye-filling techniques in brain slices, combined with high-resolution confocal microscopy, we report increased excitatory synaptic inputs and dendritic spine densities in early presymptomatic mice carrying a TDP-43Q331K mutation. These findings demonstrate substantive alterations in the motor cortex neural network, long before an overt degenerative phenotype has been reported. We conclude that increased excitatory neurotransmission is a common pathophysiology amongst differing genetic cases of ALS and may be of relevance to the 95% of sporadic ALS cases that exhibit TDP-43 inclusions. PMID:27897242

  13. The Effect of Noise on CaMKII Activation in a Dendritic Spine During LTP Induction

    PubMed Central

    Zeng, Shangyou

    2010-01-01

    Activation of calcium-calmodulin dependent protein kinase II (CaMKII) during induction of long-term potentiation (LTP) is a series of complicated stochastic processes that are affected by noise. There are two main sources of noise affecting CaMKII activation within a dendritic spine. One is the noise associated with stochastic opening of N-methyl-d-aspartate (NMDA) receptor channels and the other is the noise associated with the stochastic reaction-diffusion kinetics leading to CaMKII activation. Many models have been developed to simulate CaMKII activation, but there is no fully stochastic model that studies the effect of noise on CaMKII activation. Here we construct a fully stochastic model to study these effects. Our results show that noise has important effects on CaMKII activation variability, with the effect from stochastic opening of NMDA receptor channels being 5–10 times more significant than that from stochastic reactions involving CaMKII. In addition, CaMKII activation levels and the variability of activation are greatly affected by small changes in NMDA receptor channel number at the synapse. One reason LTP induction protocols may require tetanic or repeated burst stimulation is that there is a need to overcome inherent variability to provide sufficiently large calcium signals through NMDA receptor channels; with meaningful physiological stimuli, noise may allow the calcium signal to exceed threshold for CaMKII activation when it might not do so otherwise. PMID:20107130

  14. Cell class-specific regulation of neocortical dendrite and spine growth by AMPA receptor splice and editing variants.

    PubMed

    Hamad, Mohammad I K; Ma-Högemeier, Zhan-Lu; Riedel, Christian; Conrads, Claudius; Veitinger, Thomas; Habijan, Tim; Schulz, Jan-Niklas; Krause, Martin; Wirth, Marcus J; Hollmann, Michael; Wahle, Petra

    2011-10-01

    Glutamatergic transmission converging on calcium signaling plays a key role in dendritic differentiation. In early development, AMPA receptor (AMPAR) transcripts are extensively spliced and edited to generate subunits that differ in their biophysical properties. Whether these subunits have specific roles in the context of structural differentiation is unclear. We have investigated the role of nine GluA variants and revealed a correlation between the expression of flip variants and the period of major dendritic growth. In interneurons, only GluA1(Q)-flip increased dendritic length and branching. In pyramidal cells, GluA2(Q)-flop, GluA2(Q)-flip, GluA3(Q)-flip and calcium-impermeable GluA2(R)-flip promoted dendritic growth, suggesting that flip variants with slower desensitization kinetics are more important than receptors with elevated calcium permeability. Imaging revealed significantly higher calcium signals in pyramidal cells transfected with GluA2(R)-flip as compared with GluA2(R)-flop, suggesting a contribution of voltage-activated calcium channels. Indeed, dendritic growth induced by GluA2(R)-flip in pyramidal cells was prevented by blocking NMDA receptors (NMDARs) or voltage-gated calcium channels (VGCCs), suggesting that they act downstream of AMPARs. Intriguingly, the action of GluA1(Q)-flip in interneurons was also dependent on NMDARs and VGCCs. Cell class-specific effects were not observed for spine formation, as GluA2(Q)-flip and GluA2(Q)-flop increased spine density in pyramidal cells as well as in interneurons. The results suggest that AMPAR variants expressed early in development are important determinants for activity-dependent dendritic growth in a cell type-specific and cell compartment-specific manner.

  15. Dendritic spine density, morphology, and fibrillar actin content surrounding amyloid-β plaques in a mouse model of amyloid-β deposition.

    PubMed

    Kirkwood, Caitlin M; Ciuchta, Jennifer; Ikonomovic, Milos D; Fish, Kenneth N; Abrahamson, Eric E; Murray, Patrick S; Klunk, William E; Sweet, Robert A

    2013-08-01

    Dendritic spines are the site of most excitatory synapses, the loss of which correlates with cognitive impairment in patients with Alzheimer disease. Substantial evidence indicates that amyloid-β (Aβ) peptide, either insoluble fibrillar Aβ deposited into plaques or soluble nonfibrillar Aβ species, can cause spine loss but the concurrent contributions of fibrillar Aβ and nonfibrillar Aβ to spine loss has not been previously assessed. We used multiple-label immunohistochemistry to measure spine density, size, and F-actin content surrounding plaques in the cerebral cortex in the PSAPP mouse model of Aβ deposition. Our approach allowed us to measure fibrillar Aβ plaque content and an index of nonfibrillar Aβ species concurrently. We found that spine density was reduced within 6 μm of the plaque perimeter, remaining spines were more compact, and F-actin content per spine was increased. Measures of fibrillar Aβ plaque content were associated with reduced spine density near plaques, whereas measures of nonfibrillar Aβ species were associated with reduced spine density and size but not altered F-actin content. These findings suggest that strategies to preserve dendritic spines in AD patients may need to address both nonfibrillar and fibrillar forms of Aβ and that nonfibrillar Aβ may exert spine toxicity through pathways not mediated by depolymerization of F-actin.

  16. Opposite Effects of mGluR1a and mGluR5 Activation on Nucleus Accumbens Medium Spiny Neuron Dendritic Spine Density

    PubMed Central

    Gross, Kellie S.; Brandner, Dieter D.; Martinez, Luis A.; Olive, M. Foster; Meisel, Robert L.

    2016-01-01

    The group I metabotropic glutamate receptors (mGluR1a and mGluR5) are important modulators of neuronal structure and function. Although these receptors share common signaling pathways, they are capable of having distinct effects on cellular plasticity. We investigated the individual effects of mGluR1a or mGluR5 activation on dendritic spine density in medium spiny neurons in the nucleus accumbens (NAc), which has become relevant with the potential use of group I mGluR based therapeutics in the treatment of drug addiction. We found that systemic administration of mGluR subtype-specific positive allosteric modulators had opposite effects on dendritic spine densities. Specifically, mGluR5 positive modulation decreased dendritic spine densities in the NAc shell and core, but was without effect in the dorsal striatum, whereas increased spine densities in the NAc were observed with mGluR1a positive modulation. Additionally, direct activation of mGluR5 via CHPG administration into the NAc also decreased the density of dendritic spines. These data provide insight on the ability of group I mGluRs to induce structural plasticity in the NAc and demonstrate that the group I mGluRs are capable of producing not just distinct, but opposing, effects on dendritic spine density. PMID:27618534

  17. Postpartum corticosterone administration reduces dendritic complexity and increases the density of mushroom spines of hippocampal CA3 arbours in dams.

    PubMed

    Workman, J L; Brummelte, S; Galea, L A M

    2013-02-01

    Postpartum depression (PPD) affects approximately 15% of mothers after giving birth. A complete understanding of depression during the postpartum period has yet to be established, although disruptions in the hypothalamic-pituitary-adrenal axis and stress during the postpartum may be involved. To model these components in rats, we administered high corticosterone (CORT) postpartum, which increases immobility in the forced swim test (FST), and reduces maternal care, body weight and hippocampal cell proliferation in dams. The hippocampus is altered in response to chronic stress, exposure to high glucocorticoids and in major depression in humans. In the present study, we examined whether high CORT reduced dendritic complexity and spines in the CA3 region of the hippocampus. Additionally, housing complexity was manipulated so that dams and litters were housed either with tubes (complex) or without tubes (impoverished) to investigate the consequences of new animal care regulations. Dams received 40 mg/kg/day of CORT or oil starting on day 2 postpartum for 23 days. Maternal behaviours were assessed on postpartum days 2-8 and dams were tested using the FST on days 21 and 22. Dams were killed on day 24 and brains were processed for Golgi impregnation. Pyramidal cells in the CA3 subfield were traced using a camera lucida and analysed for branch points and dendritic complexity, as well as spine density and type on both basal and apical arbours. As previously established, high CORT postpartum reduced maternal care and increased immobility in the FST, which is a measure of depressive-like behaviour. High CORT postpartum reduced the complexity of basal arbours and increased mushroom spines on both apical and basal dendrites. Housing complexity had no effect on spines of CA3 pyramidal cells but modest effects on cell morphology. These data show that chronic high CORT in postpartum females alters hippocampal morphology and may provide insight regarding the neurobiological

  18. The ROCK Inhibitor Fasudil Prevents Chronic Restraint Stress-Induced Depressive-Like Behaviors and Dendritic Spine Loss in Rat Hippocampus

    PubMed Central

    García-Rojo, Gonzalo; Fresno, Cristóbal; Vilches, Natalia; Díaz-Véliz, Gabriela; Mora, Sergio; Aguayo, Felipe; Pacheco, Aníbal; Parra-Fiedler, Nicolás; Parra, Claudio S.; Rojas, Paulina S.; Tejos, Macarena; Aliaga, Esteban

    2017-01-01

    Abstract Background: Dendritic arbor simplification and dendritic spine loss in the hippocampus, a limbic structure implicated in mood disorders, are assumed to contribute to symptoms of depression. These morphological changes imply modifications in dendritic cytoskeleton. Rho GTPases are regulators of actin dynamics through their effector Rho kinase. We have reported that chronic stress promotes depressive-like behaviors in rats along with dendritic spine loss in apical dendrites of hippocampal pyramidal neurons, changes associated with Rho kinase activation. The present study proposes that the Rho kinase inhibitor Fasudil may prevent the stress-induced behavior and dendritic spine loss. Methods: Adult male Sprague-Dawley rats were injected with saline or Fasudil (i.p., 10 mg/kg) starting 4 days prior to and maintained during the restraint stress procedure (2.5 h/d for 14 days). Nonstressed control animals were injected with saline or Fasudil for 18 days. At 24 hours after treatment, forced swimming test, Golgi-staining, and immuno-western blot were performed. Results: Fasudil prevented stress-induced immobility observed in the forced swimming test. On the other hand, Fasudil-treated control animals showed behavioral patterns similar to those of saline-treated controls. Furthermore, we observed that stress induced an increase in the phosphorylation of MYPT1 in the hippocampus, an exclusive target of Rho kinase. This change was accompanied by dendritic spine loss of apical dendrites of pyramidal hippocampal neurons. Interestingly, increased pMYPT1 levels and spine loss were both prevented by Fasudil administration. Conclusion: Our findings suggest that Fasudil may prevent the development of abnormal behavior and spine loss induced by chronic stress by blocking Rho kinase activity. PMID:27927737

  19. Loss of neuronal GSK3β reduces dendritic spine stability and attenuates excitatory synaptic transmission via β-catenin

    PubMed Central

    Ochs, S M; Dorostkar, M M; Aramuni, G; Schön, C; Filser, S; Pöschl, J; Kremer, A; Van Leuven, F; Ovsepian, S V; Herms, J

    2015-01-01

    Central nervous glycogen synthase kinase 3β (GSK3β) is implicated in a number of neuropsychiatric diseases, such as bipolar disorder, depression, schizophrenia, fragile X syndrome or anxiety disorder. Many drugs employed to treat these conditions inhibit GSK3β either directly or indirectly. We studied how conditional knockout of GSK3β affected structural synaptic plasticity. Deletion of the GSK3β gene in a subset of cortical and hippocampal neurons in adult mice led to reduced spine density. In vivo imaging revealed that this was caused by a loss of persistent spines, whereas stabilization of newly formed spines was reduced. In electrophysiological recordings, these structural alterations correlated with a considerable drop in the frequency and amplitude of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-dependent miniature excitatory postsynaptic currents. Expression of constitutively active β-catenin caused reduction in spine density and electrophysiological alterations similar to GSK3β knockout, suggesting that the effects of GSK3β knockout were mediated by the accumulation of β-catenin. In summary, changes of dendritic spines, both in quantity and in morphology, are correlates of experience-dependent synaptic plasticity; thus, these results may help explain the mechanism of action of psychotropic drugs inhibiting GSK3β. PMID:24912492

  20. Distinct dendritic spine and nuclear phases of calcineurin activation after exposure to Amyloid β revealed by a novel FRET assay

    PubMed Central

    Wu, Hai-Yan; Hudry, Eloise; Hashimoto, Tadafumi; Uemura, Kengo; Fan, Zhan-Yun; Berezovska, Oksana; Grosskreutz, Cynthia L.; Bacskai, Brian J.; Hyman, Bradley T

    2012-01-01

    Calcineurin (CaN) activation is critically involved in the regulation of spine morphology in response to oligomeric amyloid β (Aβ) as well as in synaptic plasticity in normal memory, but no existing techniques can monitor the spatiotemporal pattern of CaN activity. Here we use a spectral Fluorescence Resonance Energy Transfer (FRET) approach to monitor CaN activation dynamics in real time with subcellular resolution. When oligomeric Aβ derived from Tg2576 murine transgenic neurons or human AD brains were applied to wild-type murine primary cortical neurons, we observe a dynamic progression of CaN activation within minutes, first in dendritic spines, then in the cytoplasm and, in hours, in the nucleus. CaN activation in spines leads to rapid but reversible morphological changes in spines and in postsynaptic proteins; longer exposure leads to NFAT translocation to the nucleus and frank spine loss. These results provide a framework for understanding calcineurin’s role in synaptic alterations associated with AD pathogenesis. PMID:22496575

  1. KIS, a kinase associated with microtubule regulators, enhances translation of AMPA receptors and stimulates dendritic spine remodeling.

    PubMed

    Pedraza, Neus; Ortiz, Raúl; Cornadó, Alba; Llobet, Artur; Aldea, Martí; Gallego, Carme

    2014-10-15

    Local regulation of protein synthesis allows a neuron to rapidly alter the proteome in response to synaptic signals, an essential mechanism in synaptic plasticity that is altered in many neurological diseases. Synthesis of many synaptic proteins is under local control and much of this regulation occurs through structures termed RNA granules. KIS is a protein kinase that associates with stathmin, a modulator of the tubulin cytoskeleton. Furthermore, KIS is found in RNA granules and stimulates translation driven by the β-actin 3'UTR in neurites. Here we explore the physiological and molecular mechanisms underlying the action of KIS on hippocampal synaptic plasticity in mice. KIS downregulation compromises spine development, alters actin dynamics, and reduces postsynaptic responsiveness. The absence of KIS results in a significant decrease of protein levels of PSD-95, a postsynaptic scaffolding protein, and the AMPAR subunits GluR1 and GluR2 in a CPEB3-dependent manner. Underlying its role in spine maturation, KIS is able to suppress the spine developmental defects caused by CPEB3 overexpression. Moreover, either by direct or indirect mechanisms, KIS counteracts the inhibitory activity of CPEB3 on the GluR2 3'UTR at both mRNA translation and polyadenylation levels. Our study provides insights into the mechanisms that mediate dendritic spine morphogenesis and functional synaptic maturation, and suggests KIS as a link regulating spine cytoskeleton and postsynaptic activity in memory formation.

  2. Reconstruction of the Upper Cervical Spine Using a Personalized 3D-Printed Vertebral Body in an Adolescent With Ewing Sarcoma.

    PubMed

    Xu, Nanfang; Wei, Feng; Liu, Xiaoguang; Jiang, Liang; Cai, Hong; Li, Zihe; Yu, Miao; Wu, Fengliang; Liu, Zhongjun

    2016-01-01

    Case report. To describe a three-dimensional (3D) printed axial vertebral body used in upper cervical spine reconstruction after a C2 Ewing sarcoma resection in an adolescent boy. Ewing sarcoma is a malignant musculoskeletal neoplasm with a peak incidence in adolescents. Cervical spine as the primary site of the tumor has been related to a worse prognosis. Tumor resection is particularly challenging in the atlantoaxial region due to complexity of the anatomy, necessity for extensive resection according to oncological principles, and a lack of specialized implants for reconstruction. 3D printing refers to a process where 3D objects are created through successive layering of material under computer control. Although this technology potentially enables accurate fabrication of patient-specific orthopedic implants, literature on its utilization in this regard is rare. A 12-year-old boy with a C2 Ewing sarcoma underwent a staged spondylectomy. Wide resection of the posterior elements was first performed. Two weeks later, a high anterior retropharyngeal approach was taken to remove the remains of the C2 vertebra. A customized artificial vertebral body fabricated according to a computer model using titanium alloy powder was inserted to replace the defect between C1 and C3. The microstructure of the implant was optimized for better biomechanical stability and enhanced bone healing. Patient had an uneventful recovery and began to ambulate on postoperative day 7. Adjuvant treatment commenced 3 weeks after the surgery. He was tumor-free at the 1-year follow-up. Computed tomography studies revealed evidence of implant osseointegration and no subsidence or displacement of the construct. This is a case example on the concept of personalized precision medicine in a surgical setting and demonstrates how 3D-printed, patient-specific implants may bring individualized solutions to rare problems wherein restoration of the specific anatomy of each patient is a key prognostic factor.

  3. Chronic Lead Exposure and Mixed Factors of Gender×Age×Brain Regions Interactions on Dendrite Growth, Spine Maturity and NDR Kinase

    PubMed Central

    Xue, Weizhen; Yang, Qian-Qian; Wang, Shuang; Xu, Yi; Wang, Hui-Li

    2015-01-01

    NDR1/2 kinase is essential in dendrite morphology and spine formation, which is regulated by cellular Ca2+. Lead (Pb) is a potent blocker of L-type calcium channel and our recent work showed Pb exposure impairs dendritic spine outgrowth in hippocampal neurons in rats. But the sensitivity of Pb-induced spine maturity with mixed factors (gender×age×brain regions) remains unknown. This study aimed to systematically investigate the effect of Pb exposure on spine maturity in rat brain with three factors (gender×age×brain regions), as well as the NDR1/2 kinase expression. Sprague–Dawley rats were exposed to Pb from parturition to postnatal day 30, 60, 90, respectively. Golgi-Cox staining was used to examine spine maturity. Western blot assay was applied to measure protein expression and real-time fluorescence quantitative PCR assay was used to examine mRNA levels. The results showed chronic Pb exposure significantly decreased dendritic length and impaired spine maturity in both rat hippocampus and medial prefrontal cortex. The impairment of dendritic length induced by Pb exposure tended to adolescence > adulthood, hippocampus > medial prefrontal cortex and female > male. Pb exposure induced significant damage in spine maturity during adolescence and early adult while little damage during adult in male rat brain and female medial prefrontal cortex. Besides, there was sustained impairment from adolescence to adulthood in female hippocampus. Interestingly, impairment of spine maturity followed by Pb exposure was correlated with NDR1/2 kinase. The reduction of NDR1/2 kinase protein expression after Pb exposure was similar to the result of spine maturity. In addition, NDR2 and their substrate Rabin3 mRNA levels were significantly decreased by Pb exposure in developmental rat brain. Taken together, Pb exposure impaired dendrite growth and maturity which was subject to gender×age×brain regions effects and related to NDR1/2 signal expression. PMID:26368815

  4. Chronic Lead Exposure and Mixed Factors of Gender×Age×Brain Regions Interactions on Dendrite Growth, Spine Maturity and NDR Kinase.

    PubMed

    Du, Yang; Ge, Meng-Meng; Xue, Weizhen; Yang, Qian-Qian; Wang, Shuang; Xu, Yi; Wang, Hui-Li

    2015-01-01

    NDR1/2 kinase is essential in dendrite morphology and spine formation, which is regulated by cellular Ca2+. Lead (Pb) is a potent blocker of L-type calcium channel and our recent work showed Pb exposure impairs dendritic spine outgrowth in hippocampal neurons in rats. But the sensitivity of Pb-induced spine maturity with mixed factors (gender×age×brain regions) remains unknown. This study aimed to systematically investigate the effect of Pb exposure on spine maturity in rat brain with three factors (gender×age×brain regions), as well as the NDR1/2 kinase expression. Sprague-Dawley rats were exposed to Pb from parturition to postnatal day 30, 60, 90, respectively. Golgi-Cox staining was used to examine spine maturity. Western blot assay was applied to measure protein expression and real-time fluorescence quantitative PCR assay was used to examine mRNA levels. The results showed chronic Pb exposure significantly decreased dendritic length and impaired spine maturity in both rat hippocampus and medial prefrontal cortex. The impairment of dendritic length induced by Pb exposure tended to adolescence > adulthood, hippocampus > medial prefrontal cortex and female > male. Pb exposure induced significant damage in spine maturity during adolescence and early adult while little damage during adult in male rat brain and female medial prefrontal cortex. Besides, there was sustained impairment from adolescence to adulthood in female hippocampus. Interestingly, impairment of spine maturity followed by Pb exposure was correlated with NDR1/2 kinase. The reduction of NDR1/2 kinase protein expression after Pb exposure was similar to the result of spine maturity. In addition, NDR2 and their substrate Rabin3 mRNA levels were significantly decreased by Pb exposure in developmental rat brain. Taken together, Pb exposure impaired dendrite growth and maturity which was subject to gender×age×brain regions effects and related to NDR1/2 signal expression.

  5. Fatigue reversibly reduced cortical and hippocampal dendritic spines concurrent with compromise of motor endurance and spatial memory.

    PubMed

    Chen, J-R; Wang, T-J; Huang, H-Y; Chen, L-J; Huang, Y-S; Wang, Y-J; Tseng, G-F

    2009-07-21

    Fatigue could be induced following forced exercise, sickness, heat stroke or sleep disturbance and impaired brain-related functions such as concentration, attention and memory. Here we investigated whether fatigue altered the dendrites of central neurons. Central fatigue was induced by housing rats in cage with 1.5-cm deep water for 1-5 days. Three days of sleep deprivation seriously compromised rats' performance in weight-loaded forced swimming and spatial learning tests, and 5 days of treatment worsened it further. Combinations of intracellular dye injection and three-dimensional analysis revealed that dendritic spines on retrograde tracer-identified corticospinal neurons and Cornu Ammonis (CA)1 and CA3 pyramidal neurons were significantly reduced while the shape or length of the dendritic arbors was not altered. Three days of rest restored the spine loss and the degraded spatial learning and weight-loaded forced swimming performances to control levels. In conclusion, although we could not rule out additional non-hypothalamic-pituitary-adrenal stress, the apparent fatigue induced following a few days of sleep deprivation could change brain structurally and functionally and the effects were reversible with a few days of rest.

  6. Distinct Ca2+ sources in dendritic spines of hippocampal CA1 neurons couple to SK and Kv4 channels

    PubMed Central

    Wang, Kang; Lin, Mike T.; Adelman, John P.; Maylie, James

    2013-01-01

    SUMMARY Ca2+-activated SK channels and voltage-gated A-type Kv4 channels shape dendritic excitatory postsynaptic potentials (EPSPs) in hippocampal CA1 pyramidal neurons. Synaptically evoked Ca2+ influx through N-methyl-D-aspartate receptors (NMDARs) activates spine SK channels, reducing EPSPs and the associated spine head Ca2+ transient. However, results using glutamate uncaging implicated Ca2+ influx through SNX-482 (SNX) sensitive Cav2.3 (R-type) Ca2+ channels as the Ca2+ source for SK channel activation. The present findings show that using Schaffer collateral stimulation the effects of SNX and apamin are not mutually exclusive and SNX increases EPSPs independent of SK channel activity. Dialysis with 1,2-bis(o-aminophenoxy)ethane-N’N’N’-tetraacetic acid (BAPTA), application of 4-Aminopyridine (4-AP), expression of a Kv4.2 dominant negative subunit, and dialysis with a KChIPs antibody occluded the SNX-induced increase of EPSPs. The results suggest two distinct Ca2+ signaling pathways within dendritic spines, that links Ca2+ influx through NMDARs to SK channels and Ca2+ influx through R-type Ca2+ channels to Kv4.2-containing channels. PMID:24462100

  7. Pharmacological reversion of sphingomyelin-induced dendritic spine anomalies in a Niemann Pick disease type A mouse model

    PubMed Central

    Arroyo, Ana I; Camoletto, Paola G; Morando, Laura; Sassoe-Pognetto, Marco; Giustetto, Maurizio; Van Veldhoven, Paul P; Schuchman, Edward H; Ledesma, Maria D

    2014-01-01

    Understanding the role of lipids in synapses and the aberrant molecular mechanisms causing the cognitive deficits that characterize most lipidosis is necessary to develop therapies for these diseases. Here we describe sphingomyelin (SM) as a key modulator of the dendritic spine actin cytoskeleton. We show that increased SM levels in neurons of acid sphingomyelinase knock out mice (ASMko), which mimic Niemann Pick disease type A (NPA), result in reduced spine number and size and low levels of filamentous actin. Mechanistically, SM accumulation decreases the levels of metabotropic glutamate receptors type I (mGluR1/5) at the synaptic membrane impairing membrane attachment and activity of RhoA and its effectors ROCK and ProfilinIIa. Pharmacological enhancement of the neutral sphingomyelinase rescues the aberrant molecular and morphological phenotypes in vitro and in vivo and improves motor and memory deficits in ASMko mice. Altogether, these data demonstrate the influence of SM and its catabolic enzymes in dendritic spine physiology and contribute to our understanding of the cognitive deficits of NPA patients, opening new perspectives for therapeutic interventions. Subject Categories Genetics, Gene Therapy & Genetic Disease; Neuroscience PMID:24448491

  8. Pharmacological reversion of sphingomyelin-induced dendritic spine anomalies in a Niemann Pick disease type A mouse model.

    PubMed

    Arroyo, Ana I; Camoletto, Paola G; Morando, Laura; Sassoe-Pognetto, Marco; Giustetto, Maurizio; Van Veldhoven, Paul P; Schuchman, Edward H; Ledesma, Maria D

    2014-03-01

    Understanding the role of lipids in synapses and the aberrant molecular mechanisms causing the cognitive deficits that characterize most lipidosis is necessary to develop therapies for these diseases. Here we describe sphingomyelin (SM) as a key modulator of the dendritic spine actin cytoskeleton. We show that increased SM levels in neurons of acid sphingomyelinase knock out mice (ASMko), which mimic Niemann Pick disease type A (NPA), result in reduced spine number and size and low levels of filamentous actin. Mechanistically, SM accumulation decreases the levels of metabotropic glutamate receptors type I (mGluR1/5) at the synaptic membrane impairing membrane attachment and activity of RhoA and its effectors ROCK and ProfilinIIa. Pharmacological enhancement of the neutral sphingomyelinase rescues the aberrant molecular and morphological phenotypes in vitro and in vivo and improves motor and memory deficits in ASMko mice. Altogether, these data demonstrate the influence of SM and its catabolic enzymes in dendritic spine physiology and contribute to our understanding of the cognitive deficits of NPA patients, opening new perspectives for therapeutic interventions.

  9. Activity-regulated Somatostatin Expression Reduces Dendritic Spine Density and Lowers Excitatory Synaptic Transmission via Postsynaptic Somatostatin Receptor 4*

    PubMed Central

    Hou, Zai-Hua; Yu, Xiang

    2013-01-01

    Neuronal activity regulates multiple aspects of the morphological and functional development of neural circuits. One mechanism by which it achieves this is through regulation of gene expression. In a screen for activity-induced genes, we identified somatostatin (SST), a neuropeptide secreted by the SST subtype of interneurons. Using real time quantitative PCR and ELISA, we showed that persistent elevation of neuronal activity increased both the gene expression and protein secretion of SST over a relatively prolonged time course of 48 h. Using primary hippocampal neuronal cultures, we found that SST treatment for 1 day significantly reduced the density of dendritic spines, the morphological bases of excitatory synapses. Furthermore, the density of pre- and postsynaptic markers of excitatory synapses was significantly lowered following SST treatment, whereas that of inhibitory synapses was not affected. Consistently, SST treatment reduced the frequency of miniature excitatory postsynaptic currents, without affecting inhibition. Finally, lowering the endogenous level of SST receptor subtype 4 in individual hippocampal pyramidal neurons significantly blocked the effect of SST in reducing spine density and excitatory synaptic transmission in a cell autonomous fashion, suggesting that the effect of SST in regulating excitatory synaptic transmission is mainly mediated by SST receptor subtype 4. Together, our results demonstrated that activity-dependent release of SST reduced the density of dendritic spines and the number of excitatory synapses through postsynaptic activation of SST receptor subtype 4 in pyramidal neurons. To our knowledge, this is the first demonstration of the long term effect of SST on neuronal morphology. PMID:23233668

  10. Two-color super-resolution imaging of dendritic spines of hippocampal neurons using a custom STED microscope

    NASA Astrophysics Data System (ADS)

    Meyer, Stephanie; Woolfrey, Kevin; Ozbay, Baris; Restrepo, Diego; Dell'Acqua, Mark; Gibson, Emily

    2014-03-01

    We built a 2-color STED microscope and imaged dendritic spines in mouse hippocampal neurons at sub-diffraction limit resolution. The microscope is designed similar to one developed by Johanna Bückers, et. al. (Opt. Exp. 2011) in the lab of Dr. Stefan Hell. The STED microscope images at Atto590/Atto647N wavelengths and is capable of doing so simultaneously. We characterized the resolution of the system by imaging 40nm fluorescent beads as ~58nm (Atto590) and ~44 nm (Atto647N). The microscope is part of the UC Denver Advanced Light Microscopy Core, primarily for use by neuroscientists. We then performed 2-color STED imaging on hippocampal neurons immuno-labeled at PSD-95 (a postsynaptic density marker) along with either the GluA1-subunit of the AMPA-type glutamate receptor or the signaling scaffold protein AKAP150 in order to visualize nm-scale compartmentalization of these proteins within single postsynaptic dendritic spines. Importantly, for both GluA1 and AKAP150, STED imaging visualized sub-diffraction dimension clusters in spines located at both synaptic (overlapping or proximal to PSD-95) and extrasynaptic locations. In the future 2-color STED imaging should be useful for studying changes in the localization of these proteins during synaptic plasticity. NIH Shared Instrumentation Grant Program.

  11. WE-AB-BRA-01: 3D-2D Image Registration for Target Localization in Spine Surgery: Comparison of Similarity Metrics Against Robustness to Content Mismatch

    SciTech Connect

    De Silva, T; Ketcha, M; Siewerdsen, J H; Uneri, A; Reaungamornrat, S; Vogt, S; Kleinszig, G; Lo, S F; Wolinsky, J P; Gokaslan, Z L; Aygun, N

    2015-06-15

    Purpose: In image-guided spine surgery, mapping 3D preoperative images to 2D intraoperative images via 3D-2D registration can provide valuable assistance in target localization. However, the presence of surgical instrumentation, hardware implants, and soft-tissue resection/displacement causes mismatches in image content, confounding existing registration methods. Manual/semi-automatic methods to mask such extraneous content is time consuming, user-dependent, error prone, and disruptive to clinical workflow. We developed and evaluated 2 novel similarity metrics within a robust registration framework to overcome such challenges in target localization. Methods: An IRB-approved retrospective study in 19 spine surgery patients included 19 preoperative 3D CT images and 50 intraoperative mobile radiographs in cervical, thoracic, and lumbar spine regions. A neuroradiologist provided truth definition of vertebral positions in CT and radiography. 3D-2D registration was performed using the CMA-ES optimizer with 4 gradient-based image similarity metrics: (1) gradient information (GI); (2) gradient correlation (GC); (3) a novel variant referred to as gradient orientation (GO); and (4) a second variant referred to as truncated gradient correlation (TGC). Registration accuracy was evaluated in terms of the projection distance error (PDE) of the vertebral levels. Results: Conventional similarity metrics were susceptible to gross registration error and failure modes associated with the presence of surgical instrumentation: for GI, the median PDE and interquartile range was 33.0±43.6 mm; similarly for GC, PDE = 23.0±92.6 mm respectively. The robust metrics GO and TGC, on the other hand, demonstrated major improvement in PDE (7.6 ±9.4 mm and 8.1± 18.1 mm, respectively) and elimination of gross failure modes. Conclusion: The proposed GO and TGC similarity measures improve registration accuracy and robustness to gross failure in the presence of strong image content mismatch. Such

  12. Drebrin depletion alters neurotransmitter receptor levels in protein complexes, dendritic spine morphogenesis and memory-related synaptic plasticity in the mouse hippocampus.

    PubMed

    Jung, Gangsoo; Kim, Eun-Jung; Cicvaric, Ana; Sase, Sunetra; Gröger, Marion; Höger, Harald; Sialana, Fernando Jayson; Berger, Johannes; Monje, Francisco J; Lubec, Gert

    2015-07-01

    Drebrin an actin-bundling key regulator of dendritic spine genesis and morphology, has been recently proposed as a regulator of hippocampal glutamatergic activity which is critical for memory formation and maintenance. Here, we examined the effects of genetic deletion of drebrin on dendritic spine and on the level of complexes containing major brain receptors. To this end, homozygous and heterozygous drebrin knockout mice generated in our laboratory and related wild-type control animals were studied. Level of protein complexes containing dopamine receptor D1/dopamine receptor D2, 5-hydroxytryptamine receptor 1A (5-HT1(A)R), and 5-hydroxytryptamine receptor 7 (5-HT7R) were significantly reduced in hippocampus of drebrin knockout mice whereas no significant changes were detected for GluR1, 2, and 3 and NR1 as examined by native gel-based immunoblotting. Drebrin depletion also altered dendritic spine formation, morphology, and reduced levels of dopamine receptor D1 in dendritic spines as evaluated using immunohistochemistry/confocal microscopy. Electrophysiological studies further showed significant reduction in memory-related hippocampal synaptic plasticity upon drebrin depletion. These findings provide unprecedented experimental support for a role of drebrin in the regulation of memory-related synaptic plasticity and neurotransmitter receptor signaling, offer relevant information regarding the interpretation of previous studies and help in the design of future studies on dendritic spines. © 2015 International Society for Neurochemistry.

  13. The therapeutic effect of memantine through the stimulation of synapse formation and dendritic spine maturation in autism and fragile X syndrome.

    PubMed

    Wei, Hongen; Dobkin, Carl; Sheikh, Ashfaq M; Malik, Mazhar; Brown, W Ted; Li, Xiaohong

    2012-01-01

    Although the pathogenic mechanisms that underlie autism are not well understood, there is evidence showing that metabotropic and ionotropic glutamate receptors are hyper-stimulated and the GABAergic system is hypo-stimulated in autism. Memantine is an uncompetitive antagonist of NMDA receptors and is widely prescribed for treatment of Alzheimer's disease treatment. Recently, it has been shown to improve language function, social behavior, and self-stimulatory behaviors of some autistic subjects. However the mechanism by which memantine exerts its effect remains to be elucidated. In this study, we used cultured cerebellar granule cells (CGCs) from Fmr1 knockout (KO) mice, a mouse model for fragile X syndrome (FXS) and syndromic autism, to examine the effects of memantine on dendritic spine development and synapse formation. Our results show that the maturation of dendritic spines is delayed in Fmr1-KO CGCs. We also detected reduced excitatory synapse formation in Fmr1-KO CGCs. Memantine treatment of Fmr1-KO CGCs promoted cell adhesion properties. Memantine also stimulated the development of mushroom-shaped mature dendritic spines and restored dendritic spine to normal levels in Fmr1-KO CGCs. Furthermore, we demonstrated that memantine treatment promoted synapse formation and restored the excitatory synapses to a normal range in Fmr1-KO CGCs. These findings suggest that memantine may exert its therapeutic capacity through a stimulatory effect on dendritic spine maturation and excitatory synapse formation, as well as promoting adhesion of CGCs.

  14. Essential role for vav Guanine nucleotide exchange factors in brain-derived neurotrophic factor-induced dendritic spine growth and synapse plasticity.

    PubMed

    Hale, Carly F; Dietz, Karen C; Varela, Juan A; Wood, Cody B; Zirlin, Benjamin C; Leverich, Leah S; Greene, Robert W; Cowan, Christopher W

    2011-08-31

    Brain-derived neurotrophic factor (BDNF) and its cognate receptor, TrkB, regulate a wide range of cellular processes, including dendritic spine formation and functional synapse plasticity. However, the signaling mechanisms that link BDNF-activated TrkB to F-actin remodeling enzymes and dendritic spine morphological plasticity remain poorly understood. We report here that BDNF/TrkB signaling in neurons activates the Vav family of Rac/RhoA guanine nucleotide exchange factors through a novel TrkB-dependent mechanism. We find that Vav is required for BDNF-stimulated Rac-GTP production in cortical and hippocampal neurons. Vav is partially enriched at excitatory synapses in the postnatal hippocampus but does not appear to be required for normal dendritic spine density. Rather, we observe significant reductions in both BDNF-induced, rapid, dendritic spine head growth and in CA3-CA1 theta burst-stimulated long-term potentiation in Vav-deficient mouse hippocampal slices, suggesting that Vav-dependent regulation of dendritic spine morphological plasticity facilitates normal functional synapse plasticity.

  15. Accumulation of Polyribosomes in Dendritic Spine Heads, But Not Bases and Necks, during Memory Consolidation Depends on Cap-Dependent Translation Initiation.

    PubMed

    Ostroff, Linnaea E; Botsford, Benjamin; Gindina, Sofya; Cowansage, Kiriana K; LeDoux, Joseph E; Klann, Eric; Hoeffer, Charles

    2017-02-15

    Translation in dendrites is believed to support synaptic changes during memory consolidation. Although translational control mechanisms are fundamental mediators of memory, little is known about their role in local translation. We previously found that polyribosomes accumulate in dendritic spines of the adult rat lateral amygdala (LA) during consolidation of aversive pavlovian conditioning and that this memory requires cap-dependent initiation, a primary point of translational control in eukaryotic cells. Here we used serial electron microscopy reconstructions to quantify polyribosomes in LA dendrites when consolidation was blocked by the cap-dependent initiation inhibitor 4EGI-1. We found that 4EGI-1 depleted polyribosomes in dendritic shafts and selectively prevented their upregulation in spine heads, but not bases and necks, during consolidation. Cap-independent upregulation was specific to spines with small, astrocyte-associated synapses. Our results reveal that cap-dependent initiation is involved in local translation during learning and that local translational control varies with synapse type.SIGNIFICANCE STATEMENT Translation initiation is a central regulator of long-term memory formation. Local translation in dendrites supports memory by providing necessary proteins at synaptic sites, but it is unknown whether this requires initiation or bypasses it. We used serial electron microscopy reconstructions to examine polyribosomes in dendrites when memory formation was blocked by an inhibitor of translation initiation. This revealed two major pools of polyribosomes that were upregulated during memory formation: one pool in dendritic spine heads that was initiation dependent and another pool in the bases and necks of small spines that was initiation independent. Thus, translation regulation differs between spine types and locations, and translation that occurs closest to individual synapses during memory formation is initiation dependent. Copyright © 2017 the

  16. Association of Anxiety and Depression With Microtubule-Associated Protein 2– and Synaptopodin-Immunolabeled Dendrite and Spine Densities in Hippocampal CA3 of Older Humans

    PubMed Central

    Soetanto, Ainie; Wilson, Robert S.; Talbot, Konrad; Un, Ashley; Schneider, Julie A.; Sobiesk, Mark; Kelly, Jeremiah; Leurgans, Sue; Bennett, David A.; Arnold, Steven E.

    2010-01-01

    Context Chronic psychological distress has deleterious effects on many of the body’s physiological systems. In experimental animal models, chronic stress leads to neuroanatomic changes in the hippocampus, in particular a decrease in the length and branching of dendrites as well as a decrease in the number of dendritic spines. Objectives To examine whether analogous distress-related neuroanatomic changes occur in humans and whether such changes might also be related to cognitive dysfunction observed in older people who report greater psychological distress. Design Postmortem study of brain tissues from participants of the Religious Orders Study, an ongoing population-based clinicopathological study of aging and cognition. Setting The Rush University Religious Orders Study and the University of Pennsylvania Cellular and Molecular Neuropathology Program. Participants Seventy-two deceased participants of the Religious Orders Study. Main Outcome Measures Densities of microtubule-associated protein 2–immunolabeled dendrites and synaptopodin-immunolabeled dendritic spines in the CA3 subfield of the hippocampus, quantified using semiautomated image acquisition and analysis. Results Higher levels of trait anxiety and longitudinal depression scores were associated with decreased densities of dendrites and spines in CA3. Dendrite and spine densities did not correlate with an index of global cognition or with densities of common age-related pathological changes. Conclusions Regressive neuronal changes occur in humans who experience greater psychological distress. These changes are analogous to neuronal changes in animal models of chronic stress. PMID:20439826

  17. Myosin II ATPase Activity Mediates the Long-Term Potentiation-Induced Exodus of Stable F-Actin Bound by Drebrin A from Dendritic Spines

    PubMed Central

    Mizui, Toshiyuki; Sekino, Yuko; Yamazaki, Hiroyuki; Ishizuka, Yuta; Takahashi, Hideto; Kojima, Nobuhiko; Kojima, Masami; Shirao, Tomoaki

    2014-01-01

    The neuronal actin-binding protein drebrin A forms a stable structure with F-actin in dendritic spines. NMDA receptor activation causes an exodus of F-actin bound by drebrin A (DA-actin) from dendritic spines, suggesting a pivotal role for DA-actin exodus in synaptic plasticity. We quantitatively assessed the extent of DA-actin localization to spines using the spine-dendrite ratio of drebrin A in cultured hippocampal neurons, and found that (1) chemical long-term potentiation (LTP) stimulation induces rapid DA-actin exodus and subsequent DA-actin re-entry in dendritic spines, (2) Ca2+ influx through NMDA receptors regulates the exodus and the basal accumulation of DA-actin, and (3) the DA-actin exodus is blocked by myosin II ATPase inhibitor, but is not blocked by myosin light chain kinase (MLCK) or Rho-associated kinase (ROCK) inhibitors. These results indicate that myosin II mediates the interaction between NMDA receptor activation and DA-actin exodus in LTP induction. Furthermore, myosin II seems to be activated by a rapid actin-linked mechanism rather than slow MLC phosphorylation. Thus the myosin-II mediated DA-actin exodus might be an initial event in LTP induction, triggering actin polymerization and spine enlargement. PMID:24465547

  18. Myosin II ATPase activity mediates the long-term potentiation-induced exodus of stable F-actin bound by drebrin A from dendritic spines.

    PubMed

    Mizui, Toshiyuki; Sekino, Yuko; Yamazaki, Hiroyuki; Ishizuka, Yuta; Takahashi, Hideto; Kojima, Nobuhiko; Kojima, Masami; Shirao, Tomoaki

    2014-01-01

    The neuronal actin-binding protein drebrin A forms a stable structure with F-actin in dendritic spines. NMDA receptor activation causes an exodus of F-actin bound by drebrin A (DA-actin) from dendritic spines, suggesting a pivotal role for DA-actin exodus in synaptic plasticity. We quantitatively assessed the extent of DA-actin localization to spines using the spine-dendrite ratio of drebrin A in cultured hippocampal neurons, and found that (1) chemical long-term potentiation (LTP) stimulation induces rapid DA-actin exodus and subsequent DA-actin re-entry in dendritic spines, (2) Ca(2+) influx through NMDA receptors regulates the exodus and the basal accumulation of DA-actin, and (3) the DA-actin exodus is blocked by myosin II ATPase inhibitor, but is not blocked by myosin light chain kinase (MLCK) or Rho-associated kinase (ROCK) inhibitors. These results indicate that myosin II mediates the interaction between NMDA receptor activation and DA-actin exodus in LTP induction. Furthermore, myosin II seems to be activated by a rapid actin-linked mechanism rather than slow MLC phosphorylation. Thus the myosin-II mediated DA-actin exodus might be an initial event in LTP induction, triggering actin polymerization and spine enlargement.

  19. Deletion of KIBRA, protein expressed in kidney and brain, increases filopodial-like long dendritic spines in neocortical and hippocampal neurons in vivo and in vitro

    PubMed Central

    Blanque, Anja; Repetto, Daniele; Rohlmann, Astrid; Brockhaus, Johannes; Duning, Kerstin; Pavenstädt, Hermann; Wolff, Ilka; Missler, Markus

    2015-01-01

    Spines are small protrusions arising from dendrites that receive most excitatory synaptic input in the brain. Dendritic spines represent dynamic structures that undergo activity-dependent adaptations, for example, during synaptic plasticity. Alterations of spine morphology, changes of spine type ratios or density have consequently been found in paradigms of learning and memory, and accompany many neuropsychiatric disorders. Polymorphisms in the gene encoding KIBRA, a protein present in kidney and brain, are linked to memory performance and cognition in humans and mouse models. Deletion of KIBRA impairs long-term synaptic plasticity and postsynaptic receptor recycling but no information is available on the morphology of dendritic spines in null-mutant mice. Here, we directly examine the role of KIBRA in spinous synapses using knockout mice. Since KIBRA is normally highly expressed in neocortex and hippocampus at juvenile age, we analyze synapse morphology in intact tissue and in neuronal cultures from these brain regions. Quantification of different dendritic spine types in Golgi-impregnated sections and in transfected neurons coherently reveal a robust increase of filopodial-like long protrusions in the absence of KIBRA. While distribution of pre- and postsynaptic marker proteins, overall synapse ultrastructure and density of asymmetric contacts were remarkably normal, electron microscopy additionally uncovered less perforated synapses and spinules in knockout neurons. Thus, our results indicate that KIBRA is involved in the maintenance of normal ratios of spinous synapses, and may thus provide a structural correlate of altered cognitive functions when this memory-associated molecule is mutated. PMID:25750616

  20. Synaptic Basis for Cross-modal Plasticity: Enhanced Supragranular Dendritic Spine Density in Anterior Ectosylvian Auditory Cortex of the Early Deaf Cat.

    PubMed

    Clemo, H Ruth; Lomber, Stephen G; Meredith, M Alex

    2016-04-01

    In the cat, the auditory field of the anterior ectosylvian sulcus (FAES) is sensitive to auditory cues and its deactivation leads to orienting deficits toward acoustic, but not visual, stimuli. However, in early deaf cats, FAES activity shifts to the visual modality and its deactivation blocks orienting toward visual stimuli. Thus, as in other auditory cortices, hearing loss leads to cross-modal plasticity in the FAES. However, the synaptic basis for cross-modal plasticity is unknown. Therefore, the present study examined the effect of early deafness on the density, distribution, and size of dendritic spines in the FAES. Young cats were ototoxically deafened and raised until adulthood when they (and hearing controls) were euthanized, the cortex stained using Golgi-Cox, and FAES neurons examined using light microscopy. FAES dendritic spine density averaged 0.85 spines/μm in hearing animals, but was significantly higher (0.95 spines/μm) in the early deaf. Size distributions and increased spine density were evident specifically on apical dendrites of supragranular neurons. In separate tracer experiments, cross-modal cortical projections were shown to terminate predominantly within the supragranular layers of the FAES. This distributional correspondence between projection terminals and dendritic spine changes indicates that cross-modal plasticity is synaptically based within the supragranular layers of the early deaf FAES. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  1. Synaptic Basis for Cross-modal Plasticity: Enhanced Supragranular Dendritic Spine Density in Anterior Ectosylvian Auditory Cortex of the Early Deaf Cat

    PubMed Central

    Clemo, H. Ruth; Lomber, Stephen G.; Meredith, M. Alex

    2016-01-01

    In the cat, the auditory field of the anterior ectosylvian sulcus (FAES) is sensitive to auditory cues and its deactivation leads to orienting deficits toward acoustic, but not visual, stimuli. However, in early deaf cats, FAES activity shifts to the visual modality and its deactivation blocks orienting toward visual stimuli. Thus, as in other auditory cortices, hearing loss leads to cross-modal plasticity in the FAES. However, the synaptic basis for cross-modal plasticity is unknown. Therefore, the present study examined the effect of early deafness on the density, distribution, and size of dendritic spines in the FAES. Young cats were ototoxically deafened and raised until adulthood when they (and hearing controls) were euthanized, the cortex stained using Golgi-Cox, and FAES neurons examined using light microscopy. FAES dendritic spine density averaged 0.85 spines/μm in hearing animals, but was significantly higher (0.95 spines/μm) in the early deaf. Size distributions and increased spine density were evident specifically on apical dendrites of supragranular neurons. In separate tracer experiments, cross-modal cortical projections were shown to terminate predominantly within the supragranular layers of the FAES. This distributional correspondence between projection terminals and dendritic spine changes indicates that cross-modal plasticity is synaptically based within the supragranular layers of the early deaf FAES. PMID:25274986

  2. Modulation of dendritic spine development and plasticity by BDNF and vesicular trafficking: fundamental roles in neurodevelopmental disorders associated with mental retardation and autism.

    PubMed

    Chapleau, Christopher A; Larimore, Jennifer L; Theibert, Anne; Pozzo-Miller, Lucas

    2009-09-01

    The process of axonal and dendritic development establishes the synaptic circuitry of the central nervous system (CNS) and is the result of interactions between intrinsic molecular factors and the external environment. One growth factor that has a compelling function in neuronal development is the neurotrophin brain-derived neurotrophic factor (BDNF). BDNF participates in axonal and dendritic differentiation during embryonic stages of neuronal development, as well as in the formation and maturation of dendritic spines during postnatal development. Recent studies have also implicated vesicular trafficking of BDNF via secretory vesicles, and both secretory and endosomal trafficking of vesicles containing synaptic proteins, such as neurotransmitter and neurotrophin receptors, in the regulation of axonal and dendritic differentiation, and in dendritic spine morphogenesis. Several genes that are either mutated or deregulated in neurodevelopmental disorders associated with mental retardation have now been identified, and several mouse models of these disorders have been generated and characterized. Interestingly, abnormalities in dendritic and synaptic structure are consistently observed in human neurodevelopmental disorders associated with mental retardation, and in mouse models of these disorders as well. Abnormalities in dendritic and synaptic differentiation are thought to underlie altered synaptic function and network connectivity, thus contributing to the clinical outcome. Here, we review the roles of BDNF and vesicular trafficking in axonal and dendritic differentiation in the context of dendritic and axonal morphological impairments commonly observed in neurodevelopmental disorders associated with mental retardation.

  3. Effects of ethanol exposure and withdrawal on dendritic morphology and spine density in the nucleus accumbens core and shell.

    PubMed

    Peterson, Veronica L; McCool, Brian A; Hamilton, Derek A

    2015-01-12

    Exposure to drugs of abuse can result in profound structural modifications on neurons in circuits involved in addiction that may contribute to drug dependence, withdrawal and related processes. Structural alterations on medium spiny neurons (MSNs) of the nucleus accumbens (NAc) have been observed following exposure to and withdrawal from a variety of drugs; however, relatively little is known about the effects of alcohol exposure and withdrawal on structural alterations of NAc MSNs. In the present study male rats were chronically exposed to vaporized ethanol for 10 days and underwent 1 or 7 days of withdrawal after which the brains were processed for Golgi-Cox staining and analysis of dendritic length, branching and spine density. MSNs of the NAc shell and core underwent different patterns of changes following ethanol exposure and withdrawal. At 1 day of withdrawal there were modest reductions in the dendritic length and branching of MSNs in both the core and the shell compared to control animals exposed only to air. At 7 days of withdrawal the length and branching of shell MSNs was reduced, whereas the length and branching of core MSNs were increased relative to the shell. The density of mature spines was increased in the core at 1 day of withdrawal, whereas the density of less mature spines was increased in both regions at 7 days of withdrawal. Collectively, these observations indicate that MSNs of the NAc core and shell undergo distinct patterns of structural modifications following ethanol exposure and withdrawal suggesting that modifications in dendritic structure in these regions may contribute differentially to ethanol withdrawal.

  4. Dendritic Spine Loss and Chronic White Matter Inflammation in a Mouse Model of Highly Repetitive Head Trauma

    PubMed Central

    Winston, Charisse N.; Noël, Anastasia; Neustadtl, Aidan; Parsadanian, Maia; Barton, David J.; Chellappa, Deepa; Wilkins, Tiffany E.; Alikhani, Andrew D.; Zapple, David N.; Villapol, Sonia; Planel, Emmanuel; Burns, Mark P.

    2017-01-01

    Mild traumatic brain injury (mTBI) is an emerging risk for chronic behavioral, cognitive, and neurodegenerative conditions. Athletes absorb several hundred mTBIs each year; however, rodent models of repeat mTBI (rmTBI) are often limited to impacts in the single digits. Herein, we describe the effects of 30 rmTBIs, examining structural and pathological changes in mice up to 365 days after injury. We found that single mTBI causes a brief loss of consciousness and a transient reduction in dendritic spines, reflecting a loss of excitatory synapses. Single mTBI does not cause axonal injury, neuroinflammation, or cell death in the gray or white matter. Thirty rmTBIs with a 1-day interval between each mTBI do not cause dendritic spine loss; however, when the interinjury interval is increased to 7 days, dendritic spine loss is reinstated. Thirty rmTBIs cause white matter pathology characterized by positive silver and Fluoro-Jade B staining, and microglial proliferation and activation. This pathology continues to develop through 60 days, and is still apparent at 365 days, after injury. However, rmTBIs did not increase β-amyloid levels or tau phosphorylation in the 3xTg-AD mouse model of Alzheimer disease. Our data reveal that single mTBI causes a transient loss of synapses, but that rmTBIs habituate to repetitive injury within a short time period. rmTBI causes the development of progressive white matter pathology that continues for months after the final impact. PMID:26857506

  5. Modulations of NeuroD activity contribute to the differential effects of morphine and fentanyl on dendritic spine stability

    PubMed Central

    Hui, Zheng; Zeng, Yan; Chu, Ji; Kam, Angel YuetFang; Loh, Horace H.; Law, Ping-Yee

    2010-01-01

    The cellular level of neurogenic differentiation 1 (NeuroD) is modulated differentially by μ-opioid receptor agonists: fentanyl increases NeuroD level by reducing the amount of miR-190, an inhibitor of NeuroD expression, whereas morphine does not alter NeuroD level. In the current study, NeuroD activity was demonstrated to be also under agonist-dependent regulation. After three-day treatment, morphine and fentanyl decreased the activity of the Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα), which phosphorylates and activates NeuroD. Because NeuroD activity is determined by both the CaMKIIα activity and the cellular NeuroD level, the overall NeuroD activity was reduced by morphine, but maintained during fentanyl treatment. The differential effects of agonists on NeuroD activity were further confirmed by measuring the mRNA levels of four NeuroD downstream targets: doublecortin, Notch1, NeuroD4 and Roundabout 1. Decreased dendritic spine stability and μ-opioid receptor signaling capability were also observed when NeuroD activity was attenuated by miR-190 overexpression or treatment with KN93, a CaMKIIα inhibitor. The decrease could be rescued by NeuroD overexpression which restored NeuroD activity to the basal level. Furthermore, elevating NeuroD activity attenuated the morphine-induced decrease in dendritic spine stability. Therefore, by regulating NeuroD activity, μ-opioid receptor agonists modulate the stability of dendritic spines. PMID:20554861

  6. Serotonin 5-HT7 receptor increases the density of dendritic spines and facilitates synaptogenesis in forebrain neurons.

    PubMed

    Speranza, Luisa; Labus, Josephine; Volpicelli, Floriana; Guseva, Daria; Lacivita, Enza; Leopoldo, Marcello; Bellenchi, Gian Carlo; di Porzio, Umberto; Bijata, Monika; Perrone-Capano, Carla; Ponimaskin, Evgeni

    2017-01-25

    Precise control of dendritic spine density and synapse formation is critical for normal and pathological brain functions. Therefore, signaling pathways influencing dendrite outgrowth and remodeling remain a subject of extensive investigations. Here we report that prolonged activation of the serotonin 5-HT7 receptor (5-HT7R) with selective agonist LP-211 promotes formation of dendritic spines and facilitates synaptogenesis in postnatal cortical and striatal neurons. Critical role of 5-HT7R in neuronal morphogenesis was confirmed by analysis of neurons isolated from 5-HT7R-deficient mice and by pharmacological inactivation of the receptor. Acute activation of 5-HT7R results in pronounced neurite elongation in postnatal striatal and cortical neurons, thus extending previous data on the morphogenic role of 5-HT7R in embryonic and hippocampal neurons. We also observed decreased number of spines in neurons with either genetically (i.e. 5-HT7R-KO) or pharmacologically (i.e. antagonist treatment) blocked 5-HT7R, suggesting that constitutive 5-HT7R activity is critically involved in the spinogenesis. Moreover, cyclin-dependent kinase 5 (Cdk5) and small GTPase Cdc42 were identified as important downstream effectors mediating morphogenic effects of 5-HT7R in neurons. Altogether, our data suggest that the 5-HT7R-mediated structural reorganization during the postnatal development might have a crucial role for the development and plasticity of forebrain areas such as cortex and striatum, and thereby can be implicated in regulation of the higher cognitive functions. This article is protected by copyright. All rights reserved.

  7. Actin/alpha-actinin-dependent transport of AMPA receptors in dendritic spines: role of the PDZ-LIM protein RIL.

    PubMed

    Schulz, Torsten W; Nakagawa, Terunaga; Licznerski, Pawel; Pawlak, Verena; Kolleker, Alexander; Rozov, Andrei; Kim, Jinhyun; Dittgen, Tanjew; Köhr, Georg; Sheng, Morgan; Seeburg, Peter H; Osten, Pavel

    2004-09-29

    The efficacy of excitatory transmission in the brain depends to a large extent on synaptic AMPA receptors, hence the importance of understanding the delivery and recycling of the receptors at the synaptic sites. Here we report a novel regulation of the AMPA receptor transport by a PDZ (postsynaptic density-95/Drosophila disc large tumor suppressor zona occludens 1) and LIM (Lin11/rat Isl-1/Mec3) domain-containing protein, RIL (reversion-induced LIM protein). We show that RIL binds to the AMPA glutamate receptor subunit GluR-A C-terminal peptide via its LIM domain and to alpha-actinin via its PDZ domain. RIL is enriched in the postsynaptic density fraction isolated from rat forebrain, strongly localizes to dendritic spines in cultured neurons, and coprecipitates, together with alpha-actinin, in a protein complex isolated by immunoprecipitation of AMPA receptors from forebrain synaptosomes. Functionally, in heterologous cells, RIL links AMPA receptors to the alpha-actinin/actin cytoskeleton, an effect that appears to apply selectively to the endosomal surface-internalized population of the receptors. In cultured neurons, an overexpression of recombinant RIL increases the accumulation of AMPA receptors in dendritic spines, both at the total level, as assessed by immunodetection of endogenous GluR-A-containing receptors, and at the synaptic surface, as assessed by recording of miniature EPSCs. Our results thus indicate that RIL directs the transport of GluR-A-containing AMPA receptors to and/or within dendritic spines, in an alpha-actinin/actin-dependent manner, and that such trafficking function promotes the synaptic accumulation of the receptors.

  8. Dendritic Spine Loss and Chronic White Matter Inflammation in a Mouse Model of Highly Repetitive Head Trauma.

    PubMed

    Winston, Charisse N; Noël, Anastasia; Neustadtl, Aidan; Parsadanian, Maia; Barton, David J; Chellappa, Deepa; Wilkins, Tiffany E; Alikhani, Andrew D; Zapple, David N; Villapol, Sonia; Planel, Emmanuel; Burns, Mark P

    2016-03-01

    Mild traumatic brain injury (mTBI) is an emerging risk for chronic behavioral, cognitive, and neurodegenerative conditions. Athletes absorb several hundred mTBIs each year; however, rodent models of repeat mTBI (rmTBI) are often limited to impacts in the single digits. Herein, we describe the effects of 30 rmTBIs, examining structural and pathological changes in mice up to 365 days after injury. We found that single mTBI causes a brief loss of consciousness and a transient reduction in dendritic spines, reflecting a loss of excitatory synapses. Single mTBI does not cause axonal injury, neuroinflammation, or cell death in the gray or white matter. Thirty rmTBIs with a 1-day interval between each mTBI do not cause dendritic spine loss; however, when the interinjury interval is increased to 7 days, dendritic spine loss is reinstated. Thirty rmTBIs cause white matter pathology characterized by positive silver and Fluoro-Jade B staining, and microglial proliferation and activation. This pathology continues to develop through 60 days, and is still apparent at 365 days, after injury. However, rmTBIs did not increase β-amyloid levels or tau phosphorylation in the 3xTg-AD mouse model of Alzheimer disease. Our data reveal that single mTBI causes a transient loss of synapses, but that rmTBIs habituate to repetitive injury within a short time period. rmTBI causes the development of progressive white matter pathology that continues for months after the final impact. Copyright © 2016 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  9. An in vitro reproduction of stress-induced memory defects: Effects of corticoids on dendritic spine dynamics.

    PubMed

    Saito, Shinichi; Kimura, Satoshi; Adachi, Naoki; Numakawa, Tadahiro; Ogura, Akihiko; Tominaga-Yoshino, Keiko

    2016-01-14

    Previously, in organotypic slice culture of rodent hippocampus we found that three repeated inductions of LTP, but not a single induction, led to a slow-developing long-lasting enhancement of synaptic strength coupled with synapse formation. Naming this structural plasticity RISE (repetitive LTP-induced synaptic enhancement) and assuming it to be a potential in vitro reproduction of repetition-dependent memory consolidation, we are analyzing its cellular mechanisms. Here, we applied a glucocorticoid to the culture to mimic acute excess stress and demonstrated its blockade of RISE. Since excess stress interferes with behavioral memory consolidation, the parallelism between RISE in vitro and memory consolidation in vivo is supported. We recently reported that RISE developed after stochastic processes. Here we found that the glucocorticoid interfered with RISE by suppressing the increment of dendritic spine fluctuation that precedes a net increase in spine density. The present study provides clues for understanding the mechanism of stress-induced memory defects.

  10. An in vitro reproduction of stress-induced memory defects: Effects of corticoids on dendritic spine dynamics

    PubMed Central

    Saito, Shinichi; Kimura, Satoshi; Adachi, Naoki; Numakawa, Tadahiro; Ogura, Akihiko; Tominaga-Yoshino, Keiko

    2016-01-01

    Previously, in organotypic slice culture of rodent hippocampus we found that three repeated inductions of LTP, but not a single induction, led to a slow-developing long-lasting enhancement of synaptic strength coupled with synapse formation. Naming this structural plasticity RISE (repetitive LTP-induced synaptic enhancement) and assuming it to be a potential in vitro reproduction of repetition-dep