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Paquin-Lefebvre F, Holcman D. Voltage mapping in subcellular nanodomains using electro-diffusion modeling. J Chem Phys 2024; 161:034108. [PMID: 39007374 DOI: 10.1063/5.0215900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 06/25/2024] [Indexed: 07/16/2024] Open
Abstract
Voltage distribution in sub-cellular micro-domains such as neuronal synapses, small protrusions, or dendritic spines regulates the opening and closing of ionic channels, energy production, and thus, cellular homeostasis and excitability. Yet how voltage changes at such a small scale in vivo remains challenging due to the experimental diffraction limit, large signal fluctuations, and the still limited resolution of fast voltage indicators. Here, we study the voltage distribution in nano-compartments using a computational approach based on the Poisson-Nernst-Planck equations for the electro-diffusion motion of ions, where inward and outward fluxes are generated between channels. We report a current-voltage (I-V) logarithmic relationship generalizing Nernst law that reveals how the local membrane curvature modulates the voltage. We further find that an influx current penetrating a cellular electrolyte can lead to perturbations from tens to hundreds of nanometers deep, depending on the local channel organization. Finally, we show that the neck resistance of dendritic spines can be completely shunted by the transporters located on the head boundary, facilitating ionic flow. To conclude, we propose that voltage is regulated at a subcellular level by channel organization, membrane curvature, and narrow passages.
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Affiliation(s)
- Frédéric Paquin-Lefebvre
- Group of Data Modeling, Computational Biology and Applied Mathematics, École Normale Supérieure - Université PSL, 75005 Paris, France
| | - David Holcman
- Group of Data Modeling, Computational Biology and Applied Mathematics, École Normale Supérieure - Université PSL, 75005 Paris, France
- Department of Applied Mathematics and Theoretical Physics and Churchill College, University of Cambridge, Cambridge CB3 0WA, United Kingdom
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2
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Lee CT, Bell M, Bonilla-Quintana M, Rangamani P. Biophysical Modeling of Synaptic Plasticity. Annu Rev Biophys 2024; 53:397-426. [PMID: 38382115 DOI: 10.1146/annurev-biophys-072123-124954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Dendritic spines are small, bulbous compartments that function as postsynaptic sites and undergo intense biochemical and biophysical activity. The role of the myriad signaling pathways that are implicated in synaptic plasticity is well studied. A recent abundance of quantitative experimental data has made the events associated with synaptic plasticity amenable to quantitative biophysical modeling. Spines are also fascinating biophysical computational units because spine geometry, signal transduction, and mechanics work in a complex feedback loop to tune synaptic plasticity. In this sense, ideas from modeling cell motility can inspire us to develop multiscale approaches for predictive modeling of synaptic plasticity. In this article, we review the key steps in postsynaptic plasticity with a specific focus on the impact of spine geometry on signaling, cytoskeleton rearrangement, and membrane mechanics. We summarize the main experimental observations and highlight how theory and computation can aid our understanding of these complex processes.
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Affiliation(s)
- Christopher T Lee
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA;
| | - Miriam Bell
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA;
| | - Mayte Bonilla-Quintana
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA;
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA;
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3
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Gest AM, Grenier V, Miller EW. Optical Estimation of Membrane Potential Values Using Fluorescence Lifetime Imaging Microscopy and Hybrid Chemical-Genetic Voltage Indicators. Bioelectricity 2024; 6:34-41. [PMID: 38516638 PMCID: PMC10951690 DOI: 10.1089/bioe.2023.0027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024] Open
Abstract
Introduction Membrane potential (Vm), the voltage across a cell membrane, is an important biophysical phenomenon, central to the physiology of cells, tissues, and organisms. Voltage-sensitive fluorescent indicators are a powerful method for interrogating membrane potential in living systems, but most indicators are best suited for detecting changes in membrane potential rather than measuring values of the membrane potential. One promising approach is to use fluorescence lifetime imaging microscopy (FLIM) in combination of chemically synthesized dyes to estimate a value of membrane potential. However, a drawback is that chemically synthesized dyes show poor specificity of staining. Objectives To address this problem, we applied a chemical-genetic voltage imaging approach to FLIM to enable optical estimation of membrane potential values from genetically defined cells. Results In this report, we detail the characterization and evaluation of two of these systems in mammalian cells. We further validate the use of a FLIM-based chemical genetic voltage indicator in mammalian neurons. Conclusions Finally, we discuss opportunities for future improvements to chemical-genetic FLIM-based voltage indicators.
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Affiliation(s)
- Anneliese M.M. Gest
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Vincent Grenier
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, California, USA
- Department of Molecular & Cell Biology, University of California, Berkeley, California, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
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4
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Jędrzejewska-Szmek J, Dorman DB, Blackwell KT. Making time and space for calcium control of neuron activity. Curr Opin Neurobiol 2023; 83:102804. [PMID: 37913687 PMCID: PMC10842147 DOI: 10.1016/j.conb.2023.102804] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 11/03/2023]
Abstract
Calcium directly controls or indirectly regulates numerous functions that are critical for neuronal network activity. Intracellular calcium concentration is tightly regulated by numerous molecular mechanisms because spatial domains and temporal dynamics (not just peak amplitude) are critical for calcium control of synaptic plasticity and ion channel activation, which in turn determine neuron spiking activity. The computational models investigating calcium control are valuable because experiments achieving high spatial and temporal resolution simultaneously are technically unfeasible. Simulations of calcium nanodomains reveal that specific calcium sources can couple to specific calcium targets, providing a mechanism to determine the direction of synaptic plasticity. Cooperativity of calcium domains opposes specificity, suggesting that the dendritic branch might be the preferred computational unit of the neuron.
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Affiliation(s)
- Joanna Jędrzejewska-Szmek
- Laboratory of Neuroinformatics, Nencki Institute of Experimental Biology of Polish Academy of Science, 3 Pasteur Street, Warsaw, 02-093, Poland.
| | - Daniel B Dorman
- Department of Biomedical Engineering, Johns Hopkins University, 3400 N. Charles St., Baltimore, 21218, MD, USA
| | - Kim T Blackwell
- Bioengineering Department and Interdisciplinary Program in Neuroscience, George Mason University, 4400 University Drive, Fairfax, 22031, VA, USA
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5
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Zecevic D. Electrical properties of dendritic spines. Biophys J 2023; 122:4303-4315. [PMID: 37837192 PMCID: PMC10698282 DOI: 10.1016/j.bpj.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 09/27/2023] [Accepted: 10/11/2023] [Indexed: 10/15/2023] Open
Abstract
Dendritic spines are small protrusions that mediate most of the excitatory synaptic transmission in the brain. Initially, the anatomical structure of spines has suggested that they serve as isolated biochemical and electrical compartments. Indeed, following ample experimental evidence, it is now widely accepted that a significant physiological role of spines is to provide biochemical compartmentalization in signal integration and plasticity in the nervous system. In contrast to the clear biochemical role of spines, their electrical role is uncertain and is currently being debated. This is mainly because spines are small and not accessible to conventional experimental methods of electrophysiology. Here, I focus on reviewing the literature on the electrical properties of spines, including the initial morphological and theoretical modeling studies, indirect experimental approaches based on measurements of diffusional resistance of the spine neck, indirect experimental methods using two-photon uncaging of glutamate on spine synapses, optical imaging of intracellular calcium concentration changes, and voltage imaging with organic and genetically encoded voltage-sensitive probes. The interpretation of evidence from different preparations obtained with different methods has yet to reach a consensus, with some analyses rejecting and others supporting an electrical role of spines in regulating synaptic signaling. Thus, there is a need for a critical comparison of the advantages and limitations of different methodological approaches. The only experimental study on electrical signaling monitored optically with adequate sensitivity and spatiotemporal resolution using voltage-sensitive dyes concluded that mushroom spines on basal dendrites of cortical pyramidal neurons in brain slices have no electrical role.
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Affiliation(s)
- Dejan Zecevic
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
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6
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Pinotsis DA, Fridman G, Miller EK. Cytoelectric Coupling: Electric fields sculpt neural activity and "tune" the brain's infrastructure. Prog Neurobiol 2023; 226:102465. [PMID: 37210066 DOI: 10.1016/j.pneurobio.2023.102465] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/09/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
We propose and present converging evidence for the Cytoelectric Coupling Hypothesis: Electric fields generated by neurons are causal down to the level of the cytoskeleton. This could be achieved via electrodiffusion and mechanotransduction and exchanges between electrical, potential and chemical energy. Ephaptic coupling organizes neural activity, forming neural ensembles at the macroscale level. This information propagates to the neuron level, affecting spiking, and down to molecular level to stabilize the cytoskeleton, "tuning" it to process information more efficiently.
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Affiliation(s)
- Dimitris A Pinotsis
- Centre for Mathematical Neuroscience and Psychology and Department of Psychology, City -University of London, London EC1V 0HB, United Kingdom; The Picower Institute for Learning & Memory and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Gene Fridman
- Departments of Otolaryngology, Biomedical Engineering, and Electrical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Earl K Miller
- The Picower Institute for Learning & Memory and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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7
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Tran PD, Blanpied TA, Atzberger PJ. Protein drift-diffusion dynamics and phase separation in curved cell membranes and dendritic spines: Hybrid discrete-continuum methods. Phys Rev E 2022; 106:044402. [PMID: 36397472 DOI: 10.1103/physreve.106.044402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
We develop methods for investigating protein drift-diffusion dynamics in heterogeneous cell membranes and the roles played by geometry, diffusion, chemical kinetics, and phase separation. Our hybrid stochastic numerical methods combine discrete particle descriptions with continuum-level models for tracking the individual protein drift-diffusion dynamics when coupled to continuum fields. We show how our approaches can be used to investigate phenomena motivated by protein kinetics within dendritic spines. The spine geometry is hypothesized to play an important biological role regulating synaptic strength, protein kinetics, and self-assembly of clusters. We perform simulation studies for model spine geometries varying the neck size to investigate how phase-separation and protein organization is influenced by different shapes. We also show how our methods can be used to study the roles of geometry in reaction-diffusion systems including Turing instabilities. Our methods provide general approaches for investigating protein kinetics and drift-diffusion dynamics within curved membrane structures.
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Affiliation(s)
- Patrick D Tran
- Physics, College of Creative Studies, University of California, Santa Barbara, Santa Barbara, California 93106-3080, USA
| | - Thomas A Blanpied
- Department of Physiology, University of Maryland, Baltimore, Maryland 21201, USA
| | - Paul J Atzberger
- Department of Mathematics and Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106-3080, USA
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8
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Priel A, Dai XQ, Chen XZ, Scarinci N, Cantero MDR, Cantiello HF. Electrical recordings from dendritic spines of adult mouse hippocampus and effect of the actin cytoskeleton. Front Mol Neurosci 2022; 15:769725. [PMID: 36090255 PMCID: PMC9453158 DOI: 10.3389/fnmol.2022.769725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 07/26/2022] [Indexed: 11/28/2022] Open
Abstract
Dendritic spines (DS) are tiny protrusions implicated in excitatory postsynaptic responses in the CNS. To achieve their function, DS concentrate a high density of ion channels and dynamic actin networks in a tiny specialized compartment. However, to date there is no direct information on DS ionic conductances. Here, we used several experimental techniques to obtain direct electrical information from DS of the adult mouse hippocampus. First, we optimized a method to isolate DS from the dissected hippocampus. Second, we used the lipid bilayer membrane (BLM) reconstitution and patch clamping techniques and obtained heretofore unavailable electrical phenotypes on ion channels present in the DS membrane. Third, we also patch clamped DS directly in cultured adult mouse hippocampal neurons, to validate the electrical information observed with the isolated preparation. Electron microscopy and immunochemistry of PDS-95 and NMDA receptors and intrinsic actin networks confirmed the enrichment of the isolated DS preparation, showing open and closed DS, and multi-headed DS. The preparation was used to identify single channel activities and “whole-DS” electrical conductance. We identified NMDA and Ca2+-dependent intrinsic electrical activity in isolated DS and in situ DS of cultured adult mouse hippocampal neurons. In situ recordings in the presence of local NMDA, showed that individual DS intrinsic electrical activity often back-propagated to the dendrite from which it sprouted. The DS electrical oscillations were modulated by changes in actin cytoskeleton dynamics by addition of the F-actin disrupter agent, cytochalasin D, and exogenous actin-binding proteins. The data indicate that DS are elaborate excitable electrical devices, whose activity is a functional interplay between ion channels and the underlying actin networks. The data argue in favor of the active contribution of individual DS to the electrical activity of neurons at the level of both the membrane conductance and cytoskeletal signaling.
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Affiliation(s)
- Avner Priel
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Xiao-Qing Dai
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Xing-Zhen Chen
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Noelia Scarinci
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET) - Universidad Nacional de Santiago del Estero (UNSE), Santiago del Estero, Argentina
| | - María del Rocío Cantero
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET) - Universidad Nacional de Santiago del Estero (UNSE), Santiago del Estero, Argentina
| | - Horacio F. Cantiello
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET) - Universidad Nacional de Santiago del Estero (UNSE), Santiago del Estero, Argentina
- *Correspondence: Horacio F. Cantiello,
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9
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Post-Synapses in the Brain: Role of Dendritic and Spine Structures. Biomedicines 2022; 10:biomedicines10081859. [PMID: 36009405 PMCID: PMC9405724 DOI: 10.3390/biomedicines10081859] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/26/2022] [Accepted: 07/22/2022] [Indexed: 02/07/2023] Open
Abstract
Brain synapses are neuronal structures of the greatest interest. For a long time, however, the knowledge about them was variable, and interest was mostly focused on their pre-synaptic portions, especially neurotransmitter release from axon terminals. In the present review interest is focused on post-synapses, the structures receiving and converting pre-synaptic messages. Upon further modulation, such messages are transferred to dendritic fibers. Dendrites are profoundly different from axons; they are shorter and of variable thickness. Their post-synapses are of two types. Those called flat/intended/aspines, integrated into dendritic fibers, are very frequent in inhibitory neurons. The spines, small and stemming protrusions, connected to dendritic fibers by their necks, are present in almost all excitatory neurons. Several structures and functions including the post-synaptic densities and associated proteins, the nanoscale mechanisms of compartmentalization, the cytoskeletons of actin and microtubules, are analogous in the two post-synaptic forms. However other properties, such as plasticity and its functions of learning and memory, are largely distinct. Several properties of spines, including emersion from dendritic fibers, growth, change in shape and decreases in size up to disappearance, are specific. Spinal heads correspond to largely independent signaling compartments. They are motile, their local signaling is fast, however transport through their thin necks is slow. When single spines are activated separately, their dendritic effects are often lacking; when multiple spines are activated concomitantly, their effects take place. Defects of post-synaptic responses, especially those of spines, take place in various brain diseases. Here alterations affecting symptoms and future therapy are shown to occur in neurodegenerative diseases and autism spectrum disorders.
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10
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Rosado J, Bui VD, Haas CA, Beck J, Queisser G, Vlachos A. Calcium modeling of spine apparatus-containing human dendritic spines demonstrates an “all-or-nothing” communication switch between the spine head and dendrite. PLoS Comput Biol 2022; 18:e1010069. [PMID: 35468131 PMCID: PMC9071165 DOI: 10.1371/journal.pcbi.1010069] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 05/05/2022] [Accepted: 03/30/2022] [Indexed: 11/19/2022] Open
Abstract
Dendritic spines are highly dynamic neuronal compartments that control the synaptic transmission between neurons. Spines form ultrastructural units, coupling synaptic contact sites to the dendritic shaft and often harbor a spine apparatus organelle, composed of smooth endoplasmic reticulum, which is responsible for calcium sequestration and release into the spine head and neck. The spine apparatus has recently been linked to synaptic plasticity in adult human cortical neurons. While the morphological heterogeneity of spines and their intracellular organization has been extensively demonstrated in animal models, the influence of spine apparatus organelles on critical signaling pathways, such as calcium-mediated dynamics, is less well known in human dendritic spines. In this study we used serial transmission electron microscopy to anatomically reconstruct nine human cortical spines in detail as a basis for modeling and simulation of the calcium dynamics between spine and dendrite. The anatomical study of reconstructed human dendritic spines revealed that the size of the postsynaptic density correlates with spine head volume and that the spine apparatus volume is proportional to the spine volume. Using a newly developed simulation pipeline, we have linked these findings to spine-to-dendrite calcium communication. While the absence of a spine apparatus, or the presence of a purely passive spine apparatus did not enable any of the reconstructed spines to relay a calcium signal to the dendritic shaft, the calcium-induced calcium release from this intracellular organelle allowed for finely tuned “all-or-nothing” spine-to-dendrite calcium coupling; controlled by spine morphology, neck plasticity, and ryanodine receptors. Our results suggest that spine apparatus organelles are strategically positioned in the neck of human dendritic spines and demonstrate their potential relevance to the maintenance and regulation of spine-to-dendrite calcium communication. During the past decade it has become increasingly clear that abnormal synaptic plasticity is a major hallmark of neurological and cognitive disorders. Developing a better understanding of the synaptic plasticity process, which describes the ability of neurons to adapt their contacts in an activity-dependent manner, will lead to improved treatment of many neurological and cognitive disorders. It is known that calcium-dependent events such as synaptic transmission, intracellular calcium release, and calcium wave propagation, are required for many types of synaptic plasticity expression. However, the biological significance of these processes in neurons of the adult human cortex remains unknown. Due to technical limitations and ethical concerns, experimental data addressing this biologically and clinically relevant topic are not available. Therefore, we have implemented a computational model to study the intracellular calcium dynamics in realistic human dendritic spines based on detailed morphological reconstructions. With our model and simulations, we have established the morphological and biological requirements for the propagation of calcium from spines into the dendrites. Our results suggest a critical role for the calcium-storing spine apparatus organelle in regulating calcium homeostasis and propagation in human dendritic spines.
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Affiliation(s)
- James Rosado
- Department of Mathematics, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Viet Duc Bui
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Carola A. Haas
- Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
- Center Brain Links Brain Tools, University of Freiburg, Freiburg, Germany
- Center for Basics in Neuromodulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jürgen Beck
- Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Center for Basics in Neuromodulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Gillian Queisser
- Department of Mathematics, Temple University, Philadelphia, Pennsylvania, United States of America
- * E-mail: (GQ); (AV)
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
- Center Brain Links Brain Tools, University of Freiburg, Freiburg, Germany
- Center for Basics in Neuromodulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
- * E-mail: (GQ); (AV)
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11
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Computing Extracellular Electric Potentials from Neuronal Simulations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1359:179-199. [DOI: 10.1007/978-3-030-89439-9_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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12
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Rusakov DA, Stewart MG. Synaptic environment and extrasynaptic glutamate signals: The quest continues. Neuropharmacology 2021; 195:108688. [PMID: 34174263 DOI: 10.1016/j.neuropharm.2021.108688] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/11/2022]
Abstract
Behaviour of a mammal relies on the brain's excitatory circuits equipped with glutamatergic synapses. In most cases, glutamate escaping from the synaptic cleft is rapidly buffered and taken up by high-affinity transporters expressed by nearby perisynaptic astroglial processes (PAPs). The spatial relationship between glutamatergic synapses and PAPs thus plays a crucial role in understanding glutamate signalling actions, yet its intricate features can only be fully appreciated using methods that operate beyond the diffraction limit of light. Here, we examine principal aspects pertaining to the receptor actions of glutamate, inside and outside the synaptic cleft in the brain, where the organisation of synaptic micro-physiology and micro-environment play a critical part. In what conditions and how far glutamate can escape the synaptic cleft activating its target receptors outside the immediate synapse has long been the subject of debate. Evidence is also emerging that neuronal activity- and astroglia-dependent glutamate spillover actions could be important across the spectrum of cognitive functions This article is part of the special issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Michael G Stewart
- Dept of Life Sciences, The Open University, Milton Keynes, MK7 6AA, UK.
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13
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Steffens H, Mott AC, Li S, Wegner W, Švehla P, Kan VWY, Wolf F, Liebscher S, Willig KI. Stable but not rigid: Chronic in vivo STED nanoscopy reveals extensive remodeling of spines, indicating multiple drivers of plasticity. SCIENCE ADVANCES 2021; 7:7/24/eabf2806. [PMID: 34108204 PMCID: PMC8189587 DOI: 10.1126/sciadv.abf2806] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/22/2021] [Indexed: 06/01/2023]
Abstract
Excitatory synapses on dendritic spines of pyramidal neurons are considered a central memory locus. To foster both continuous adaption and the storage of long-term information, spines need to be plastic and stable at the same time. Here, we advanced in vivo STED nanoscopy to superresolve distinct features of spines (head size and neck length/width) in mouse neocortex for up to 1 month. While LTP-dependent changes predict highly correlated modifications of spine geometry, we find both, uncorrelated and correlated dynamics, indicating multiple independent drivers of spine remodeling. The magnitude of this remodeling suggests substantial fluctuations in synaptic strength. Despite this high degree of volatility, all spine features exhibit persistent components that are maintained over long periods of time. Furthermore, chronic nanoscopy uncovers structural alterations in the cortex of a mouse model of neurodegeneration. Thus, at the nanoscale, stable dendritic spines exhibit a delicate balance of stability and volatility.
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Affiliation(s)
- Heinz Steffens
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Alexander C Mott
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Siyuan Li
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Waja Wegner
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Pavel Švehla
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Vanessa W Y Kan
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Fred Wolf
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization; Campus Institute for Dynamics of Biological Networks, Göttingen, Germany
| | - Sabine Liebscher
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany.
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Katrin I Willig
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany.
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
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14
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Tricot A, Sokolov IM, Holcman D. Modeling the voltage distribution in a non-locally but globally electroneutral confined electrolyte medium: applications for nanophysiology. J Math Biol 2021; 82:65. [PMID: 34057627 DOI: 10.1007/s00285-021-01618-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 03/14/2021] [Accepted: 05/17/2021] [Indexed: 11/25/2022]
Abstract
The distribution of voltage in sub-micron cellular domains remains poorly understood. In neurons, the voltage results from the difference in ionic concentrations which are continuously maintained by pumps and exchangers. However, it not clear how electro-neutrality could be maintained by an excess of fast moving positive ions that should be counter balanced by slow diffusing negatively charged proteins. Using the theory of electro-diffusion, we study here the voltage distribution in a generic domain, which consists of two concentric disks (resp. ball) in two (resp. three) dimensions, where a negative charge is fixed in the inner domain. When global but not local electro-neutrality is maintained, we solve the Poisson-Nernst-Planck equation both analytically and numerically in dimension 1 (flat) and 2 (cylindrical) and found that the voltage changes considerably on a spatial scale which is much larger than the Debye screening length, which assumes electro-neutrality. The present result suggests that long-range voltage drop changes are expected in neuronal microcompartments, probably relevant to explain the activation of far away voltage-gated channels located on the surface membrane.
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Affiliation(s)
- A Tricot
- Data Modeling, Computational Biology and Predictive Medicine, Ecole Normale Supérieure PSL, 46 rue d'Ulm, 75005, Paris, France
| | - I M Sokolov
- Institute of Physics and IRIS Adlershof, Humboldt University Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - D Holcman
- Data Modeling, Computational Biology and Predictive Medicine, Ecole Normale Supérieure PSL, 46 rue d'Ulm, 75005, Paris, France.
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15
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Abstract
This work is aimed to give an electrochemical insight into the ionic transport phenomena in the cellular environment of organized brain tissue. The Nernst–Planck–Poisson (NPP) model is presented, and its applications in the description of electrodiffusion phenomena relevant in nanoscale neurophysiology are reviewed. These phenomena include: the signal propagation in neurons, the liquid junction potential in extracellular space, electrochemical transport in ion channels, the electrical potential distortions invisible to patch-clamp technique, and calcium transport through mitochondrial membrane. The limitations, as well as the extensions of the NPP model that allow us to overcome these limitations, are also discussed.
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16
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Obashi K, Taraska JW, Okabe S. The role of molecular diffusion within dendritic spines in synaptic function. J Gen Physiol 2021; 153:e202012814. [PMID: 33720306 PMCID: PMC7967910 DOI: 10.1085/jgp.202012814] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/16/2021] [Indexed: 12/21/2022] Open
Abstract
Spines are tiny nanoscale protrusions from dendrites of neurons. In the cortex and hippocampus, most of the excitatory postsynaptic sites reside in spines. The bulbous spine head is connected to the dendritic shaft by a thin membranous neck. Because the neck is narrow, spine heads are thought to function as biochemically independent signaling compartments. Thus, dynamic changes in the composition, distribution, mobility, conformations, and signaling properties of molecules contained within spines can account for much of the molecular basis of postsynaptic function and regulation. A major factor in controlling these changes is the diffusional properties of proteins within this small compartment. Advances in measurement techniques using fluorescence microscopy now make it possible to measure molecular diffusion within single dendritic spines directly. Here, we review the regulatory mechanisms of diffusion in spines by local intra-spine architecture and discuss their implications for neuronal signaling and synaptic plasticity.
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Affiliation(s)
- Kazuki Obashi
- Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Justin W. Taraska
- Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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17
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Tamada H, Blanc J, Korogod N, Petersen CC, Knott GW. Ultrastructural comparison of dendritic spine morphology preserved with cryo and chemical fixation. eLife 2020; 9:56384. [PMID: 33274717 PMCID: PMC7748412 DOI: 10.7554/elife.56384] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 12/04/2020] [Indexed: 12/25/2022] Open
Abstract
Previously, we showed that cryo fixation of adult mouse brain tissue gave a truer representation of brain ultrastructure in comparison with a standard chemical fixation method (Korogod et al., 2015). Extracellular space matched physiological measurements, there were larger numbers of docked vesicles and less glial coverage of synapses and blood capillaries. Here, using the same preservation approaches, we compared the morphology of dendritic spines. We show that the length of the spine and the volume of its head is unchanged; however, the spine neck width is thinner by more than 30% after cryo fixation. In addition, the weak correlation between spine neck width and head volume seen after chemical fixation was not present in cryo-fixed spines. Our data suggest that spine neck geometry is independent of the spine head volume, with cryo fixation showing enhanced spine head compartmentalization and a higher predicted electrical resistance between spine head and parent dendrite.
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Affiliation(s)
- Hiromi Tamada
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Biological Electron Microscopy Facility, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Functional Anatomy and Neuroscience, Graduate School of Medicine, Nagoya University, Nagoya, Japan.,Japan Society of the Promotion of Sciences (JSPS), Tokyo, Japan
| | - Jerome Blanc
- Biological Electron Microscopy Facility, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Natalya Korogod
- Biological Electron Microscopy Facility, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,School of Health Sciences (HESAV), University of Applied Sciences and Arts Western Switzerland (HES-SO), Lausanne, Switzerland
| | - Carl Ch Petersen
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Graham W Knott
- Biological Electron Microscopy Facility, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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18
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Cartailler J, Holcman D. Electrodiffusion Theory to Map the Voltage Distribution in Dendritic Spines at a Nanometer Scale. Neuron 2020; 104:440-441. [PMID: 31697920 DOI: 10.1016/j.neuron.2019.10.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 08/23/2019] [Accepted: 10/12/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Jerome Cartailler
- Institut de Biologie de l'École Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France
| | - David Holcman
- Institut de Biologie de l'École Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France; Churchill College, University of Cambridge, Cambridge CB30DS, UK.
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19
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Holcman D, Yuste R. Reply to 'Only negligible deviations from electroneutrality are expected in dendritic spines'. Nat Rev Neurosci 2019; 21:54-55. [PMID: 31700152 DOI: 10.1038/s41583-019-0239-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David Holcman
- Group of Data Modeling and Computational Biology, IBENS-PSL, École Normale Supérieure, Paris, France. .,Churchill College, DAMPT, University of Cambridge, Cambridge, UK.
| | - Rafael Yuste
- Neurotechnology Center, Department of Biological Sciences and Neuroscience, Columbia University, New York, New York, USA
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20
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No Extraction of Spine Neck Resistance from Underdetermined Equations. Neuron 2019; 104:438-439. [DOI: 10.1016/j.neuron.2019.10.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 09/27/2019] [Accepted: 10/12/2019] [Indexed: 11/20/2022]
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21
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Electrodiffusion models of synaptic potentials in dendritic spines. J Comput Neurosci 2019; 47:77-89. [PMID: 31410632 DOI: 10.1007/s10827-019-00725-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/29/2019] [Accepted: 08/01/2019] [Indexed: 12/17/2022]
Abstract
The biophysical properties of dendritic spines play a critical role in neuronal integration but are still poorly understood, due to experimental difficulties in accessing them. Spine biophysics has been traditionally explored using theoretical models based on cable theory. However, cable theory generally assumes that concentration changes associated with ionic currents are negligible and, therefore, ignores electrodiffusion, i.e. the interaction between electric fields and ionic diffusion. This assumption, while true for large neuronal compartments, could be incorrect when applied to femto-liter size structures such as dendritic spines. To extend cable theory and explore electrodiffusion effects, we use here the Poisson (P) and Nernst-Planck (NP) equations, which relate electric field to charge and Fick's law of diffusion, to model ion concentration dynamics in spines receiving excitatory synaptic potentials (EPSPs). We use experimentally measured voltage transients from spines with nanoelectrodes to explore these dynamics with realistic parameters. We find that (i) passive diffusion and electrodiffusion jointly affect the dynamics of spine EPSPs; (ii) spine geometry plays a key role in shaping EPSPs; and, (iii) the spine-neck resistance dynamically decreases during EPSPs, leading to short-term synaptic facilitation. Our formulation, which complements and extends cable theory, can be easily adapted to model ionic biophysics in other nanoscale bio-compartments.
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22
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Glasgow SD, McPhedrain R, Madranges JF, Kennedy TE, Ruthazer ES. Approaches and Limitations in the Investigation of Synaptic Transmission and Plasticity. Front Synaptic Neurosci 2019; 11:20. [PMID: 31396073 PMCID: PMC6667546 DOI: 10.3389/fnsyn.2019.00020] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/04/2019] [Indexed: 12/16/2022] Open
Abstract
The numbers and strengths of synapses in the brain change throughout development, and even into adulthood, as synaptic inputs are added, eliminated, and refined in response to ongoing neural activity. A number of experimental techniques can assess these changes, including single-cell electrophysiological recording which offers measurements of synaptic inputs with high temporal resolution. Coupled with electrical stimulation, photoactivatable opsins, and caged compounds, to facilitate fine spatiotemporal control over release of neurotransmitters, electrophysiological recordings allow for precise dissection of presynaptic and postsynaptic mechanisms of action. Here, we discuss the strengths and pitfalls of various techniques commonly used to analyze synapses, including miniature excitatory/inhibitory (E/I) postsynaptic currents, evoked release, and optogenetic stimulation. Together, these techniques can provide multiple lines of convergent evidence to generate meaningful insight into the emergence of circuit connectivity and maturation. A full understanding of potential caveats and alternative explanations for findings is essential to avoid data misinterpretation.
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Affiliation(s)
| | | | | | | | - Edward S. Ruthazer
- Department of Neurology & Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
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23
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Basnayake K, Mazaud D, Bemelmans A, Rouach N, Korkotian E, Holcman D. Fast calcium transients in dendritic spines driven by extreme statistics. PLoS Biol 2019; 17:e2006202. [PMID: 31163024 PMCID: PMC6548358 DOI: 10.1371/journal.pbio.2006202] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 04/08/2019] [Indexed: 12/21/2022] Open
Abstract
Fast calcium transients (<10 ms) remain difficult to analyse in cellular microdomains, yet they can modulate key cellular events such as trafficking, local ATP production by endoplasmic reticulum-mitochondria complex (ER-mitochondria complex), or spontaneous activity in astrocytes. In dendritic spines receiving synaptic inputs, we show here that in the presence of a spine apparatus (SA), which is an extension of the smooth ER, a calcium-induced calcium release (CICR) is triggered at the base of the spine by the fastest calcium ions arriving at a Ryanodyne receptor (RyR). The mechanism relies on the asymmetric distributions of RyRs and sarco/ER calcium-ATPase (SERCA) pumps that we predict using a computational model and further confirm experimentally in culture and slice hippocampal neurons. The present mechanism for which the statistics of the fastest particles arriving at a small target, followed by an amplification, is likely to be generic in molecular transduction across cellular microcompartments, such as thin neuronal processes, astrocytes, endfeets, or protrusions.
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Affiliation(s)
- Kanishka Basnayake
- Computational Biology and Applied Mathematics, Institut de Biologie de l'École Normale Supérieure, Paris, France
| | - David Mazaud
- Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, Paris Sciences et Lettres Research University, Paris, France
| | - Alexis Bemelmans
- Commissariat à l’Energie Atomique et aux Energies Alternatives, Département de la Recherche Fondamentale, Institut de biologie François Jacob, Molecular Imaging Research Center and Centre National de la Recherche Scientifique UMR9199, Université Paris-Sud, Neurodegenerative Diseases Laboratory, Fontenay-aux-Roses, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, Paris Sciences et Lettres Research University, Paris, France
| | - Eduard Korkotian
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
- Faculty of Biology, Perm State University, Perm, Russia
| | - David Holcman
- Computational Biology and Applied Mathematics, Institut de Biologie de l'École Normale Supérieure, Paris, France
- Department of Applied Mathematics and Theoretical Physics, Churchill College, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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24
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Cartailler J, Holcman D. Electrical transient laws in neuronal microdomains based on electro-diffusion. Phys Chem Chem Phys 2019; 20:21062-21067. [PMID: 30074044 DOI: 10.1039/c8cp02593b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The current-voltage (I-V) conversion characterizes the physiology of cellular microdomains and reflects cellular communication, excitability, and electrical transduction. Yet deriving such I-V laws remains a major challenge in most cellular microdomains due to their small sizes and the difficulty in assessing voltage with high nanometer precision. We present here novel analytical relations derived for different numbers of ionic species inside neuronal micro/nano-domains, such as dendritic spines. When a steady-state current is injected, we find a large deviation from the classical Ohm's law, showing that the spine neck resistance is insufficient to characterize electrical properties. For a constricted spine neck, modeled by a hyperboloid, we obtain a new I-V law that illustrates the consequences of narrow passages on electrical conduction. Finally, during a fast current transient, the local voltage is modulated by the distance between activated voltage-gated channels. To conclude, electro-diffusion laws can now be used to interpret voltage distribution in neuronal microdomains.
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Affiliation(s)
- J Cartailler
- Group of Computational Biology and Applied Mathematics, Ecole Normale Supérieure, 75005 Paris, France.
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25
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Cartailler J, Holcman D. Steady-state voltage distribution in three-dimensional cusp-shaped funnels modeled by PNP. J Math Biol 2019; 79:155-185. [DOI: 10.1007/s00285-019-01353-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Indexed: 11/24/2022]
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26
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Yang Y, Lu J, Zuo Y. Changes of Synaptic Structures Associated with Learning, Memory and Diseases. BRAIN SCIENCE ADVANCES 2019. [DOI: 10.26599/bsa.2018.2018.9050012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Synaptic plasticity is widely believed to be the cellular basis of learning and memory. It is influenced by various factors including development, sensory experiences, and brain disorders. Long-term synaptic plasticity is accompanied by protein synthesis and trafficking, leading to structural changes of the synapse. In this review, we focus on the synaptic structural plasticity, which has mainly been studied with in vivo two-photon laser scanning microscopy. We also discuss how a special type of synapses, the multi-contact synapses (including those formed by multi-synaptic boutons and multi-synaptic spines), are associated with experience and learning.
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Affiliation(s)
- Yang Yang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ju Lu
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA
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27
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Stringer C, Pachitariu M. Computational processing of neural recordings from calcium imaging data. Curr Opin Neurobiol 2019; 55:22-31. [DOI: 10.1016/j.conb.2018.11.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 08/29/2018] [Accepted: 11/19/2018] [Indexed: 12/28/2022]
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28
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Okamura Y, Kawanabe A, Kawai T. Voltage-Sensing Phosphatases: Biophysics, Physiology, and Molecular Engineering. Physiol Rev 2019; 98:2097-2131. [PMID: 30067160 DOI: 10.1152/physrev.00056.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-sensing phosphatase (VSP) contains a voltage sensor domain (VSD) similar to that in voltage-gated ion channels, and a phosphoinositide phosphatase region similar to phosphatase and tensin homolog deleted on chromosome 10 (PTEN). The VSP gene is conserved from unicellular organisms to higher vertebrates. Membrane depolarization induces electrical driven conformational rearrangement in the VSD, which is translated into catalytic enzyme activity. Biophysical and structural characterization has revealed details of the mechanisms underlying the molecular functions of VSP. Coupling between the VSD and the enzyme is tight, such that enzyme activity is tuned in a graded fashion to the membrane voltage. Upon VSP activation, multiple species of phosphoinositides are simultaneously altered, and the profile of enzyme activity depends on the history of the membrane potential. VSPs have been the obvious candidate link between membrane potential and phosphoinositide regulation. However, patterns of voltage change regulating VSP in native cells remain largely unknown. This review addresses the current understanding of the biophysical biochemical properties of VSP and provides new insight into the proposed functions of VSP.
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Affiliation(s)
- Yasushi Okamura
- Department of Physiology, Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University , Osaka , Japan ; and Graduate School of Frontier Biosciences, Osaka University , Osaka , Japan
| | - Akira Kawanabe
- Department of Physiology, Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University , Osaka , Japan ; and Graduate School of Frontier Biosciences, Osaka University , Osaka , Japan
| | - Takafumi Kawai
- Department of Physiology, Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University , Osaka , Japan ; and Graduate School of Frontier Biosciences, Osaka University , Osaka , Japan
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29
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OKAMURA Y, OKOCHI Y. Molecular mechanisms of coupling to voltage sensors in voltage-evoked cellular signals. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2019; 95:111-135. [PMID: 30853698 PMCID: PMC6541726 DOI: 10.2183/pjab.95.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
The voltage sensor domain (VSD) has long been studied as a unique domain intrinsic to voltage-gated ion channels (VGICs). Within VGICs, the VSD is tightly coupled to the pore-gate domain (PGD) in diverse ways suitable for its specific function in each physiological context, including action potential generation, muscle contraction and relaxation, hormone and neurotransmitter secretion, and cardiac pacemaking. However, some VSD-containing proteins lack a PGD. Voltage-sensing phosphatase contains a cytoplasmic phosphoinositide phosphatase with similarity to phosphatase and tensin homolog (PTEN). Hv1, a voltage-gated proton channel, also lacks a PGD. Within Hv1, the VSD operates as a voltage sensor, gate, and pore for both proton sensing and permeation. Hv1 has a C-terminal coiled coil that mediates dimerization for cooperative gating. Recent progress in the structural biology of VGICs and VSD proteins provides insights into the principles of VSD coupling conserved among these proteins as well as the hierarchy of protein organization for voltage-evoked cell signaling.
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Affiliation(s)
- Yasushi OKAMURA
- Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Japan
- Graduate School of Frontier Bioscience, Osaka University, Suita, Japan
| | - Yoshifumi OKOCHI
- Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Japan
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30
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Breit M, Kessler M, Stepniewski M, Vlachos A, Queisser G. Spine-to-Dendrite Calcium Modeling Discloses Relevance for Precise Positioning of Ryanodine Receptor-Containing Spine Endoplasmic Reticulum. Sci Rep 2018; 8:15624. [PMID: 30353066 PMCID: PMC6199256 DOI: 10.1038/s41598-018-33343-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 09/18/2018] [Indexed: 12/15/2022] Open
Abstract
The endoplasmic reticulum (ER) forms a complex endomembrane network that reaches into the cellular compartments of a neuron, including dendritic spines. Recent work discloses that the spine ER is a dynamic structure that enters and leaves spines. While evidence exists that ER Ca2+ release is involved in synaptic plasticity, the role of spine ER morphology remains unknown. Combining a new 3D spine generator with 3D Ca2+ modeling, we addressed the relevance of ER positioning on spine-to-dendrite Ca2+ signaling. Our simulations, which account for Ca2+ exchange on the plasma membrane and ER, show that spine ER needs to be present in distinct morphological conformations in order to overcome a barrier between the spine and dendritic shaft. We demonstrate that RyR-carrying spine ER promotes spine-to-dendrite Ca2+ signals in a position-dependent manner. Our simulations indicate that RyR-carrying ER can initiate time-delayed Ca2+ reverberation, depending on the precise position of the spine ER. Upon spine growth, structural reorganization of the ER restores spine-to-dendrite Ca2+ communication, while maintaining aspects of Ca2+ homeostasis in the spine head. Our work emphasizes the relevance of precise positioning of RyR-containing spine ER in regulating the strength and timing of spine Ca2+ signaling, which could play an important role in tuning spine-to-dendrite Ca2+ communication and homeostasis.
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Affiliation(s)
- Markus Breit
- Goethe Center for Scientific Computing, Computational Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Marcus Kessler
- Goethe Center for Scientific Computing, Computational Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Martin Stepniewski
- Goethe Center for Scientific Computing, Computational Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, 79104, Germany. .,Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.
| | - Gillian Queisser
- Department of Mathematics, Temple University, Philadelphia, USA.
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31
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Guerrier C, Holcman D. The First 100 nm Inside the Pre-synaptic Terminal Where Calcium Diffusion Triggers Vesicular Release. Front Synaptic Neurosci 2018; 10:23. [PMID: 30083101 PMCID: PMC6064743 DOI: 10.3389/fnsyn.2018.00023] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 06/29/2018] [Indexed: 12/04/2022] Open
Abstract
Calcium diffusion in the thin 100 nm layer located between the plasma membrane and docked vesicles in the pre-synaptic terminal of neuronal cells mediates vesicular fusion and synaptic transmission. Accounting for the narrow-cusp geometry located underneath the vesicle is a key ingredient that defines the probability and the time scale of calcium diffusion to bind calcium sensors for the initiation of vesicular release. We review here the time scale, the calcium binding dynamics and the consequences for asynchronous versus synchronous release. To conclude, three-dimensional modeling approaches and the associated coarse-grained simulations can now account efficiently for the precise co-organization of vesicles and Voltage-Gated-Calcium-Channel (VGCC). This co-organization is a key determinant of short-term plasticity and it shapes asynchronous release. Moreover, changing the location of VGCC from few nanometers underneath the vesicle modifies significantly the release probability. Finally, by modifying the calcium buffer concentration, a single synapse can switch from facilitation to depression.
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Affiliation(s)
- Claire Guerrier
- Department of Mathematics and Brain Research Center, University of British Columbia, Vancouver, BC, Canada
| | - David Holcman
- Group of Applied Mathematics and Computational Biology, IBENS, École Normale Supérieure, Paris, France
- Churchill College, Cambridge University, Cambridge, United Kingdom
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32
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Eyal G, Verhoog MB, Testa-Silva G, Deitcher Y, Benavides-Piccione R, DeFelipe J, de Kock CPJ, Mansvelder HD, Segev I. Human Cortical Pyramidal Neurons: From Spines to Spikes via Models. Front Cell Neurosci 2018; 12:181. [PMID: 30008663 PMCID: PMC6034553 DOI: 10.3389/fncel.2018.00181] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 06/08/2018] [Indexed: 12/19/2022] Open
Abstract
We present detailed models of pyramidal cells from human neocortex, including models on their excitatory synapses, dendritic spines, dendritic NMDA- and somatic/axonal Na+ spikes that provided new insights into signal processing and computational capabilities of these principal cells. Six human layer 2 and layer 3 pyramidal cells (HL2/L3 PCs) were modeled, integrating detailed anatomical and physiological data from both fresh and postmortem tissues from human temporal cortex. The models predicted particularly large AMPA- and NMDA-conductances per synaptic contact (0.88 and 1.31 nS, respectively) and a steep dependence of the NMDA-conductance on voltage. These estimates were based on intracellular recordings from synaptically-connected HL2/L3 pairs, combined with extra-cellular current injections and use of synaptic blockers, and the assumption of five contacts per synaptic connection. A large dataset of high-resolution reconstructed HL2/L3 dendritic spines provided estimates for the EPSPs at the spine head (12.7 ± 4.6 mV), spine base (9.7 ± 5.0 mV), and soma (0.3 ± 0.1 mV), and for the spine neck resistance (50–80 MΩ). Matching the shape and firing pattern of experimental somatic Na+-spikes provided estimates for the density of the somatic/axonal excitable membrane ion channels, predicting that 134 ± 28 simultaneously activated HL2/L3-HL2/L3 synapses are required for generating (with 50% probability) a somatic Na+ spike. Dendritic NMDA spikes were triggered in the model when 20 ± 10 excitatory spinous synapses were simultaneously activated on individual dendritic branches. The particularly large number of basal dendrites in HL2/L3 PCs and the distinctive cable elongation of their terminals imply that ~25 NMDA-spikes could be generated independently and simultaneously in these cells, as compared to ~14 in L2/3 PCs from the rat somatosensory cortex. These multi-sites non-linear signals, together with the large (~30,000) excitatory synapses/cell, equip human L2/L3 PCs with enhanced computational capabilities. Our study provides the most comprehensive model of any human neuron to-date demonstrating the biophysical and computational distinctiveness of human cortical neurons.
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Affiliation(s)
- Guy Eyal
- Department of Neurobiology, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Matthijs B Verhoog
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands.,Department of Human Biology, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Guilherme Testa-Silva
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands
| | - Yair Deitcher
- Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ruth Benavides-Piccione
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), and Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain
| | - Javier DeFelipe
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), and Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain
| | - Christiaan P J de Kock
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands
| | - Idan Segev
- Department of Neurobiology, Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
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