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Chen S, Rahn RM, Bice AR, Bice SH, Padawer-Curry JA, Hengen KB, Dougherty JD, Culver JP. Visual Deprivation during Mouse Critical Period Reorganizes Network-Level Functional Connectivity. J Neurosci 2024; 44:e1019232024. [PMID: 38538145 PMCID: PMC11079959 DOI: 10.1523/jneurosci.1019-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 03/04/2024] [Accepted: 03/12/2024] [Indexed: 04/09/2024] Open
Abstract
A classic example of experience-dependent plasticity is ocular dominance (OD) shift, in which the responsiveness of neurons in the visual cortex is profoundly altered following monocular deprivation (MD). It has been postulated that OD shifts also modify global neural networks, but such effects have never been demonstrated. Here, we use wide-field fluorescence optical imaging (WFOI) to characterize calcium-based resting-state functional connectivity during acute (3 d) MD in female and male mice with genetically encoded calcium indicators (Thy1-GCaMP6f). We first establish the fundamental performance of WFOI by computing signal to noise properties throughout our data processing pipeline. Following MD, we found that Δ band (0.4-4 Hz) GCaMP6 activity in the deprived visual cortex decreased, suggesting that excitatory activity in this region was reduced by MD. In addition, interhemispheric visual homotopic functional connectivity decreased following MD, which was accompanied by a reduction in parietal and motor homotopic connectivity. Finally, we observed enhanced internetwork connectivity between the visual and parietal cortex that peaked 2 d after MD. Together, these findings support the hypothesis that early MD induces dynamic reorganization of disparate functional networks including the association cortices.
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Affiliation(s)
- Siyu Chen
- Departments of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110
- Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
- Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Rachel M Rahn
- Departments of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110
- Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
- Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Annie R Bice
- Departments of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Seana H Bice
- Departments of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jonah A Padawer-Curry
- Departments of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Keith B Hengen
- Biology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Joseph D Dougherty
- Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
- Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110
- Intellectual and Developmental Disabilities Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Joseph P Culver
- Departments of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110
- Physics, Washington University School of Medicine, St. Louis, Missouri 63110
- Biomedical Engineering, Washington University School of Medicine, St. Louis, Missouri 63110
- Imaging Science PhD Program, Washington University School of Medicine, St. Louis, Missouri 63110
- Biophotonics Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
- Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63110
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2
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Chen S, Rahn RM, Bice AR, Bice SH, Padawer-Curry JA, Hengen KB, Dougherty JD, Culver JP. Visual deprivation during mouse critical period reorganizes network-level functional connectivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542957. [PMID: 37398380 PMCID: PMC10312598 DOI: 10.1101/2023.05.30.542957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
A classic example of experience-dependent plasticity is ocular dominance (OD) shift, in which the responsiveness of neurons in the visual cortex is profoundly altered following monocular deprivation (MD). It has been postulated that OD shifts also modify global neural networks, but such effects have never been demonstrated. Here, we used longitudinal wide-field optical calcium imaging to measure resting-state functional connectivity during acute (3-day) MD in mice. First, delta GCaMP6 power in the deprived visual cortex decreased, suggesting that excitatory activity was reduced in the region. In parallel, interhemispheric visual homotopic functional connectivity was rapidly reduced by the disruption of visual drive through MD and was sustained significantly below baseline state. This reduction of visual homotopic connectivity was accompanied by a reduction in parietal and motor homotopic connectivity. Finally, we observed enhanced internetwork connectivity between visual and parietal cortex that peaked at MD2. Together, these findings support the hypothesis that early MD induces dynamic reorganization of disparate functional networks including association cortices.
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Affiliation(s)
- Siyu Chen
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Rachel M. Rahn
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Annie R. Bice
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Seana H. Bice
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jonah A. Padawer-Curry
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Keith B. Hengen
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Joseph D. Dougherty
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA
- Intellectual and Developmental Disabilities Research Center, Washington University, St. Louis, MO 63130, USA
| | - Joseph P. Culver
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Physics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110, USA
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3
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Modulation of Visual Responses and Ocular Dominance by Contralateral Inhibitory Activation in the Mouse Visual Cortex. Int J Mol Sci 2023; 24:ijms24065750. [PMID: 36982823 PMCID: PMC10058019 DOI: 10.3390/ijms24065750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/12/2023] [Accepted: 03/14/2023] [Indexed: 03/19/2023] Open
Abstract
Both hemispheres connect with each other by excitatory callosal projections, and whether inhibitory interneurons, usually believed to have local innervation, engage in transcallosal activity modulation is unknown. Here, we used optogenetics in combination with cell-type-specific channelrhodopsin-2 expression to activate different inhibitory neuron subpopulations in the visual cortex and recorded the response of the entire visual cortex using intrinsic signal optical imaging. We found that optogenetic stimulation of inhibitory neurons reduced spontaneous activity (increase in the reflection of illumination) in the binocular area of the contralateral hemisphere, although these stimulations had different local effects ipsilaterally. The activation of contralateral interneurons differentially affected both eye responses to visual stimuli and, thus, changed ocular dominance. Optogenetic silencing of excitatory neurons affects the ipsilateral eye response and ocular dominance in the contralateral cortex to a lesser extent. Our results revealed a transcallosal effect of interneuron activation in the mouse visual cortex.
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4
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Jenks KR, Tsimring K, Ip JPK, Zepeda JC, Sur M. Heterosynaptic Plasticity and the Experience-Dependent Refinement of Developing Neuronal Circuits. Front Neural Circuits 2021; 15:803401. [PMID: 34949992 PMCID: PMC8689143 DOI: 10.3389/fncir.2021.803401] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/15/2021] [Indexed: 01/01/2023] Open
Abstract
Neurons remodel the structure and strength of their synapses during critical periods of development in order to optimize both perception and cognition. Many of these developmental synaptic changes are thought to occur through synapse-specific homosynaptic forms of experience-dependent plasticity. However, homosynaptic plasticity can also induce or contribute to the plasticity of neighboring synapses through heterosynaptic interactions. Decades of research in vitro have uncovered many of the molecular mechanisms of heterosynaptic plasticity that mediate local compensation for homosynaptic plasticity, facilitation of further bouts of plasticity in nearby synapses, and cooperative induction of plasticity by neighboring synapses acting in concert. These discoveries greatly benefited from new tools and technologies that permitted single synapse imaging and manipulation of structure, function, and protein dynamics in living neurons. With the recent advent and application of similar tools for in vivo research, it is now feasible to explore how heterosynaptic plasticity contribute to critical periods and the development of neuronal circuits. In this review, we will first define the forms heterosynaptic plasticity can take and describe our current understanding of their molecular mechanisms. Then, we will outline how heterosynaptic plasticity may lead to meaningful refinement of neuronal responses and observations that suggest such mechanisms are indeed at work in vivo. Finally, we will use a well-studied model of cortical plasticity—ocular dominance plasticity during a critical period of visual cortex development—to highlight the molecular overlap between heterosynaptic and developmental forms of plasticity, and suggest potential avenues of future research.
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Affiliation(s)
- Kyle R Jenks
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Katya Tsimring
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Jacque Pak Kan Ip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Jose C Zepeda
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Mriganka Sur
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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5
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Khalil R, Gonzalez C, Alsuwaidi S, Levitt JB. Developmental refinement of visual callosal inputs to ferret area 17. J Comp Neurol 2021; 530:804-816. [PMID: 34611910 DOI: 10.1002/cne.25246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 12/22/2022]
Abstract
Corticocortical connections link visual cortical areas in both the ipsilateral and contralateral hemispheres. We studied the postnatal refinement of callosal connections linking multiple cortical areas with ferret area 17 during the period from just before eye opening (4 weeks) to 10 weeks of age. We aimed to determine (1) whether callosal projections from multiple visual cortical areas to area 17 refine with a similar rate and (2) whether the refinement of callosal projections parallels that of intrahemispheric cortical circuits. We injected the bidirectional tracer CTb into area 17, and mapped the areal and laminar distribution of labeled cells in visual areas of the contralateral hemisphere. Like intrahemispheric projections, callosal inputs to area 17 before eye opening are dominated by Suprasylvian area Ssy (with lesser and comparable input from areas 17, 18, 19, and 21), but within 2 weeks of eye opening are jointly dominated by area 18 and Ssy inputs; however, there are fewer labeled cells in the contralateral hemisphere. Unlike intrahemispheric projections, there is no laminar reorganization of callosal inputs; in all visual areas and at all ages studied, the greatest proportion of callosal projections arises from the infragranular layers. Also, unlike intrahemispheric projections, the peak density of callosal cells in each area projecting to area 17 declines more modestly. These results reveal important similarities and differences in the postnatal reorganization of inter- and intrahemispheric projections to area 17.
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Affiliation(s)
- Reem Khalil
- Biology, Chemistry, and Environmental Sciences Department, American University of Sharjah, Sharjah, UAE.,Department of Biology MR526, City College of New York, New York, New York, USA.,Graduate Center of the City University of New York, New York, New York, USA
| | - Cyndi Gonzalez
- Department of Biology MR526, City College of New York, New York, New York, USA
| | - Shaima Alsuwaidi
- Biology, Chemistry, and Environmental Sciences Department, American University of Sharjah, Sharjah, UAE.,Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
| | - Jonathan B Levitt
- Department of Biology MR526, City College of New York, New York, New York, USA.,Graduate Center of the City University of New York, New York, New York, USA
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6
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Olavarria JF, Laing RJ, Andelin AK. Ocular dominance columns in V1 are more susceptible than associated callosal patches to imbalance of eye input during precritical and critical periods. J Comp Neurol 2021; 529:2883-2910. [PMID: 33683706 DOI: 10.1002/cne.25134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/10/2021] [Accepted: 02/27/2021] [Indexed: 11/10/2022]
Abstract
In Long Evans rats, ocular dominance columns (ODCs) in V1 overlap with patches of callosal connections. Using anatomical tracers, we found that ODCs and callosal patches are present at postnatal day 10 (P10), several days before eye opening, and about 10 days before the activation of the critical period for ocular dominance plasticity (~P20). In rats monocularly enucleated at P10 and perfused ~P20, ODCs ipsilateral to the remaining eye desegregated, indicating that rat ODCs are highly susceptible to monocular enucleation during a precritical period. Monocular enucleation during the critical period exerted significant, although smaller, effects. Monocular eye lid suture during the critical period led to a significant expansion of the ipsilateral projection from the nondeprived eye, whereas the contralateral projection invaded into, and intermixed with, ipsilateral ODCs innervated by the deprived eye. We propose that this intermixing allows callosal connections to contribute to the effects of monocular deprivation assessed in the hemisphere ipsilateral to the nondeprived eye. The ipsilateral and contralateral projections from the deprived eye did not undergo significant shrinkage. In contrast, we found that callosal patches are less susceptible to imbalance of eye input. In rats monocularly enucleated during either the precritical or critical periods, callosal patches were maintained in the hemisphere ipsilateral to the remaining eye, but desegregated in the hemisphere ipsilateral to the enucleated orbit. Callosal patches were maintained in rats binocularly enucleated at P10 or later. Similarly, monocular deprivation during the critical period had no significant effect on callosal patches in either hemisphere.
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Affiliation(s)
- Jaime F Olavarria
- Department of Psychology, and Behavior and Neuroscience Program, University of Washington, Seattle, Washington, USA
| | - Robyn J Laing
- Department of Psychology, and Behavior and Neuroscience Program, University of Washington, Seattle, Washington, USA
| | - Adrian K Andelin
- Department of Psychology, and Behavior and Neuroscience Program, University of Washington, Seattle, Washington, USA
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7
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Zheng X, Salinas KJ, Velez DXF, Nakayama T, Lin X, Banerjee D, Xu X, Gandhi SP. Host interneurons mediate plasticity reactivated by embryonic inhibitory cell transplantation in mouse visual cortex. Nat Commun 2021; 12:862. [PMID: 33558487 PMCID: PMC7870960 DOI: 10.1038/s41467-021-21097-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 01/07/2021] [Indexed: 11/12/2022] Open
Abstract
The adult brain lacks sensitivity to changes in the sensory environment found in the juvenile brain. The transplantation of embryonic interneurons has been shown to restore juvenile plasticity to the adult host visual cortex. It is unclear whether transplanted interneurons directly mediate the renewed cortical plasticity or whether these cells act indirectly by modifying the host interneuron circuitry. Here we find that the transplant-induced reorganization of mouse host circuits is specifically mediated by Neuregulin (NRG1)/ErbB4 signaling in host parvalbumin (PV) interneurons. Brief visual deprivation reduces the visual activity of host PV interneurons but has negligible effects on the responses of transplanted PV interneurons. Exogenous NRG1 both prevents the deprivation-induced reduction in the visual responses of host PV interneurons and blocks the transplant-induced reorganization of the host circuit. While deletion of ErbB4 receptors from host PV interneurons blocks cortical plasticity in the transplant recipients, deletion of the receptors from the donor PV interneurons does not. Altogether, our results indicate that transplanted embryonic interneurons reactivate cortical plasticity by rejuvenating the function of host PV interneurons.
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Affiliation(s)
- XiaoTing Zheng
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697-2715, USA
| | - Kirstie J Salinas
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697-2715, USA
| | - Dario X Figueroa Velez
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697-2715, USA
| | - Taylor Nakayama
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697-2715, USA
| | - Xiaoxiao Lin
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, CA, 92697-2715, USA
| | - Dhruba Banerjee
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697-2715, USA
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, CA, 92697-2715, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697-2715, USA
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, 92697-2715, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, 92697-2715, USA
| | - Sunil P Gandhi
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697-2715, USA.
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, 92697-2715, USA.
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8
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Wang BS, Bernardez Sarria MS, An X, He M, Alam NM, Prusky GT, Crair MC, Huang ZJ. Retinal and Callosal Activity-Dependent Chandelier Cell Elimination Shapes Binocularity in Primary Visual Cortex. Neuron 2021; 109:502-515.e7. [PMID: 33290732 PMCID: PMC7943176 DOI: 10.1016/j.neuron.2020.11.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/23/2020] [Accepted: 11/04/2020] [Indexed: 12/21/2022]
Abstract
In mammals with binocular vision, integration of the left and right visual scene relies on information in the center visual field, which are relayed from each retina in parallel and merge in the primary visual cortex (V1) through the convergence of ipsi- and contralateral geniculocortical inputs as well as transcallosal projections between two visual cortices. The developmental assembly of this binocular circuit, especially the transcallosal pathway, remains incompletely understood. Using genetic methods in mice, we found that several days before eye-opening, retinal and callosal activities drive massive apoptosis of GABAergic chandelier cells (ChCs) in the binocular region of V1. Blockade of ChC elimination resulted in a contralateral eye-dominated V1 and deficient binocular vision. As pre-vision retinal activities convey the left-right organization of the visual field, their regulation of ChC density through the transcallosal pathway may prime a nascent binocular territory for subsequent experience-driven tuning during the post-vision critical period.
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Affiliation(s)
- Bor-Shuen Wang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Maria Sol Bernardez Sarria
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
| | - Xu An
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Miao He
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Nazia M Alam
- The Burke Neurological Institute, White Plains, NY 10605, USA; Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Glen T Prusky
- The Burke Neurological Institute, White Plains, NY 10605, USA; Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Michael C Crair
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Z Josh Huang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC, USA.
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Baroncelli L, Lunghi C. Neuroplasticity of the visual cortex: in sickness and in health. Exp Neurol 2020; 335:113515. [PMID: 33132181 DOI: 10.1016/j.expneurol.2020.113515] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/14/2020] [Accepted: 10/21/2020] [Indexed: 01/18/2023]
Abstract
Brain plasticity refers to the ability of synaptic connections to adapt their function and structure in response to experience, including environmental changes, sensory deprivation and injuries. Plasticity is a distinctive, but not exclusive, property of the developing nervous system. This review introduces the concept of neuroplasticity and describes classic paradigms to illustrate cellular and molecular mechanisms underlying synapse modifiability. Then, we summarize a growing number of studies showing that the adult cerebral cortex retains a significant degree of plasticity highlighting how the identification of strategies to enhance the plastic potential of the adult brain could pave the way for the development of novel therapeutic approaches aimed at treating amblyopia and other neurodevelopmental disorders. Finally, we analyze how the visual system adjusts to neurodegenerative conditions leading to blindness and we discuss the crucial role of spared plasticity in the visual system for sight recovery.
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Affiliation(s)
- Laura Baroncelli
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy.
| | - Claudia Lunghi
- Laboratoire des systèmes perceptifs, Département d'études cognitives, École normale supérieure, PSL University, CNRS, 75005 Paris, France
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10
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Hagihara KM, Ishikawa AW, Yoshimura Y, Tagawa Y, Ohki K. Long-Range Interhemispheric Projection Neurons Show Biased Response Properties and Fine-Scale Local Subnetworks in Mouse Visual Cortex. Cereb Cortex 2020; 31:1307-1315. [PMID: 33063102 DOI: 10.1093/cercor/bhaa297] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 08/20/2020] [Accepted: 09/08/2020] [Indexed: 12/24/2022] Open
Abstract
Integration of information processed separately in distributed brain regions is essential for brain functions. This integration is enabled by long-range projection neurons, and further, concerted interactions between long-range projections and local microcircuits are crucial. It is not well known, however, how this interaction is implemented in cortical circuits. Here, to decipher this logic, using callosal projection neurons (CPNs) in layer 2/3 of the mouse visual cortex as a model of long-range projections, we found that CPNs exhibited distinct response properties and fine-scale local connectivity patterns. In vivo 2-photon calcium imaging revealed that CPNs showed a higher ipsilateral (to their somata) eye preference, and that CPN pairs showed stronger signal/noise correlation than random pairs. Slice recordings showed CPNs were preferentially connected to CPNs, demonstrating the existence of projection target-dependent fine-scale subnetworks. Collectively, our results suggest that long-range projection target predicts response properties and local connectivity of cortical projection neurons.
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Affiliation(s)
- Kenta M Hagihara
- Department of Molecular Physiology, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan.,Friedrich Miescher Institute for Biomedical Research, Basel 4058, Switzerland
| | - Ayako Wendy Ishikawa
- Division of Visual Information Processing, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.,Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan.,Keio University School of Medicine, Shinanomachi, Shinjuku-ku, 160-8582, Japan
| | - Yumiko Yoshimura
- Division of Visual Information Processing, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.,Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Yoshiaki Tagawa
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan.,Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan.,CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Kenichi Ohki
- Department of Molecular Physiology, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan.,CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.,Department of Physiology, The University of Tokyo School of Medicine, Tokyo 113-0033, Japan.,International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo School of Medicine, Tokyo 113-0033, Japan.,Institute for AI and Beyond, The University of Tokyo School of Medicine, Tokyo 113-0033, Japan
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11
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Halička J, Sahatqija E, Krasňanský M, Kapitánová K, Fedorová M, Žiak P. Visual Training in Virtual Reality in Adult Patients with Anisometric Amblyopia. CESKÁ A SLOVENSKÁ OFTALMOLOGIE : CASOPIS CESKÉ OFTALMOLOGICKÉ SPOLECNOSTI A SLOVENSKÉ OFTALMOLOGICKÉ SPOLECNOSTI 2020; 76:24-28. [PMID: 32917091 DOI: 10.31348/2020/3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE Amblyopia is one of the most common childhood disease. The average prevalence of amblyopia in children is estimated at 2-5 %. It arises during the child development until the age of six, if not treated then, it persist throught adulthood. The aim of our work is to retrospectively analyze the results of treatment of anisometropic amblyopia using dichoptical training in virtual reality in adult amblyopic patients. MATERIALS AND METHODS Our group consisted of 84 amblyopic patients with anisometropic amblyopia with an average age of 33.8 ± 9.4 years. Patients played a video game twice a week in the Oculus Rift 3D virtual reality. Together they completed 8 visual trainings, with one training lasting 60 minutes. Before and after the training we evaluated the best corrected visual acuity (BCVA). DISCUSSION Throughout the group, we observed an improvement of 0.1 BCVA from 0.48 to 0.58 Sloan table (p.
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12
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Frantz MG, Crouse EC, Sokhadze G, Ikrar T, Stephany CÉ, Nguyen C, Xu X, McGee AW. Layer 4 Gates Plasticity in Visual Cortex Independent of a Canonical Microcircuit. Curr Biol 2020; 30:2962-2973.e5. [PMID: 32589913 PMCID: PMC7919382 DOI: 10.1016/j.cub.2020.05.067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/23/2020] [Accepted: 05/20/2020] [Indexed: 01/09/2023]
Abstract
Disrupting binocular vision during a developmental critical period can yield enduring changes to ocular dominance (OD) in primary visual cortex (V1). Here we investigated how this experience-dependent plasticity is coordinated within the laminar circuitry of V1 by deleting separately in each cortical layer (L) a gene required to close the critical period, nogo-66 receptor (ngr1). Deleting ngr1 in excitatory neurons in L4, but not in L2/3, L5, or L6, prevented closure of the critical period, and adult mice remained sensitive to brief monocular deprivation. Intracortical disinhibition, but not thalamocortical disinhibition, accompanied this OD plasticity. Both juvenile wild-type mice and adult mice lacking ngr1 in L4 displayed OD plasticity that advanced more rapidly L4 than L2/3 or L5. Interestingly, blocking OD plasticity in L2/3 with the drug AM-251 did not impair OD plasticity in L5. We propose that L4 restricts disinhibition and gates OD plasticity independent of a canonical cortical microcircuit.
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Affiliation(s)
- Michael G Frantz
- Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA
| | - Emily C Crouse
- Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Guela Sokhadze
- Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Taruna Ikrar
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA
| | - Céleste-Élise Stephany
- Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA
| | - Collins Nguyen
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA.
| | - Aaron W McGee
- Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY 40202, USA; Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA.
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13
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Tantillo E, Vannini E, Cerri C, Spalletti C, Colistra A, Mazzanti CM, Costa M, Caleo M. Differential roles of pyramidal and fast-spiking, GABAergic neurons in the control of glioma cell proliferation. Neurobiol Dis 2020; 141:104942. [DOI: 10.1016/j.nbd.2020.104942] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/15/2020] [Accepted: 05/05/2020] [Indexed: 12/14/2022] Open
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14
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Leese C, Bresnahan R, Doran C, Simsek D, Fellows AD, Restani L, Caleo M, Schiavo G, Mavlyutov T, Henke T, Binz T, Davletov B. Duplication of clostridial binding domains for enhanced macromolecular delivery into neurons. Toxicon X 2020; 5:100019. [PMID: 32140681 PMCID: PMC7043326 DOI: 10.1016/j.toxcx.2019.100019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 11/25/2019] [Accepted: 12/19/2019] [Indexed: 12/03/2022] Open
Abstract
Neurological diseases constitute a quarter of global disease burden and are expected to rise worldwide with the ageing of human populations. There is an increasing need to develop new molecular systems which can deliver drugs specifically into neurons, non-dividing cells meant to last a human lifetime. Neuronal drug delivery must rely on agents which can recognise neurons with high specificity and affinity. Here we used a recently introduced ‘stapling’ system to prepare macromolecules carrying duplicated binding domains from the clostridial family of neurotoxins. We engineered individual parts of clostridial neurotoxins separately and combined them using a strong alpha-helical bundle. We show that combining two identical binding domains of tetanus and botulinum type D neurotoxins, in a sterically defined way by protein stapling, allows enhanced intracellular delivery of molecules into neurons. We also engineered a botulinum neurotoxin type C variant with a duplicated binding domain which increased enzymatic delivery compared to the native type C toxin. We conclude that duplication of the binding parts of tetanus or botulinum neurotoxins will allow production of high avidity agents which could deliver imaging reagents and large therapeutic enzymes into neurons with superior efficiency. Macromolecules carrying duplicated clostridial binding domains (Hc) were produced. Double tetanus Hc increased protein delivery into cultured rodent neurones. Double tetanus Hc increased enzyme delivery into rodent spinal cord and brain area. Double BoNT/D Hc increased enzyme delivery into rat and human neurones in culture. Recombinant double-Hc BoNT/C was engineered, increasing delivery in cell cultures.
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Affiliation(s)
- Charlotte Leese
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Rebecca Bresnahan
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Ciara Doran
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Deniz Simsek
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Alexander D Fellows
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Laura Restani
- CNR Neuroscience Institute, Pisa, 1-56124 Pisa, Italy
| | - Matteo Caleo
- CNR Neuroscience Institute, Pisa, 1-56124 Pisa, Italy
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK.,UK Dementia Research Institute, University College London, London, WC1E 6BT, UK
| | - Timur Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Tina Henke
- Institute of Cellular Biochemistry, Hannover Medical School, Hannover, 30625, Germany
| | - Thomas Binz
- Institute of Cellular Biochemistry, Hannover Medical School, Hannover, 30625, Germany
| | - Bazbek Davletov
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
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15
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Castaño-Castaño S, Feijoo-Cuaresma M, Paredes-Pacheco J, Morales-Navas M, Ruiz-Guijarro JA, Sanchez-Santed F, Nieto-Escámez F. tDCS recovers depth perception in adult amblyopic rats and reorganizes visual cortex activity. Behav Brain Res 2019; 370:111941. [PMID: 31078617 DOI: 10.1016/j.bbr.2019.111941] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 05/07/2019] [Accepted: 05/08/2019] [Indexed: 01/09/2023]
Abstract
Amblyopia or lazy eye is a neurodevelopmental disorder that arises during the infancy and is caused by the interruption of binocular sensory activity before maturation of the nervous system. This impairment causes long-term deterioration of visual skills, particularly visual acuity and depth perception. Although visual function recovery has been supposed to be decreased with age as consequence of reduced neuronal plasticity, recent studies have shown that it is possible to promote plasticity and neurorestoration in the adult brain. Thus, transcranial direct current stimulation (tDCS) has been shown effective to treat amblyopia in the adulthood. In the present work we used postnatal monocular deprivation in Long Evans rats as an experimental model of amblyopia and the cliff test task to assess depth perception. Functional brain imaging PET was used to assess the effect of tDCS on cortical and subcortical activity. Visually deprived animals ability to perceive depth in the cliff test was significantly reduced in comparison to their controls. However, after 8 sessions of tDCS applied through 8 consecutive days, depth perception of amblyopic treated animals improved reaching control level. PET data showed 18F-FDG uptake asymmetries in the visual cortex of amblyopic animals, which disappeared after tDCS treatment. The possibility of cortical reorganization and stereoscopy recovery following brain stimulation points at tDCS as a useful strategy for treating amblyopia in adulthood. Furthermore, monocular deprivation in Long Evans rats is a valuable research model to study visual cortex mechanisms involved in depth perception and neural restoration after brain stimulation.
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Affiliation(s)
- S Castaño-Castaño
- Universidad de Almeria, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada, Almería, Spain; Achucarro, Basque center for neuroscience. Science Park, edificio de la Sede UPV / EHU 48940, Leioa, Spain; NeuroDigital Technologies S.L., Prol. Camino de la Goleta 2, Edf. Celulosa I, 04007, Almería, Spain; Universidad Europea del Atlántico, Calle Isabel Torres, 21, 39011 Santander, Cantabria, Spain.
| | - M Feijoo-Cuaresma
- Molecular Imaging Unit, CIMES, Centro de Investigaciones Medico Sanitarias, General Foundation of the University of Malaga, C/ Marqués de Beccaria, 3, Campus Universitario de Teatinos, 29071, Málaga, Spain
| | - J Paredes-Pacheco
- Molecular Imaging Unit, CIMES, Centro de Investigaciones Medico Sanitarias, General Foundation of the University of Malaga, C/ Marqués de Beccaria, 3, Campus Universitario de Teatinos, 29071, Málaga, Spain; Universidade de Compostela, Department of Psychiatry, Radiology and Public Health, Molecular Imaging and Medical Physics Group, R/ de San Francisco s/n, 15782, Santiago de Compostela, Galicia, Spain
| | - M Morales-Navas
- Universidad de Almeria, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada, Almería, Spain
| | - J A Ruiz-Guijarro
- Molecular Imaging Unit, CIMES, Centro de Investigaciones Medico Sanitarias, General Foundation of the University of Malaga, C/ Marqués de Beccaria, 3, Campus Universitario de Teatinos, 29071, Málaga, Spain
| | - F Sanchez-Santed
- Universidad de Almeria, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada, Almería, Spain
| | - F Nieto-Escámez
- Universidad de Almeria, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada, Almería, Spain; Centro de Evaluación y Rehabilitación Neuropsicológica (CERNEP), Universidad de Almería, Ctra. Sacramento S/N, 04120, La Cañada, Almería, Spain; NeuroDigital Technologies S.L., Prol. Camino de la Goleta 2, Edf. Celulosa I, 04007, Almería, Spain
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16
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Abstract
The corpus callosum is a large fiber bundle which connects contralateral brain regions. After unilateral perturbations such as stroke or amputation, interhemispheric connectivity is altered and often leads to bilateral somatomotor cortical hyperactivity in patients with poor recovery. This study reports that callosal targeting of deprived layer 5 neurons is maximally potentiated in mouse primary somatosensory barrel cortex after unilateral whisker denervation. These neurons also experience an increase in excitability and spontaneous excitatory amplitudes. These results should be relevant to the cortical responses observed in human patients after unilateral nerve transection, amputation, or stroke. Central or peripheral injury causes reorganization of the brain’s connections and functions. A striking change observed after unilateral stroke or amputation is a recruitment of bilateral cortical responses to sensation or movement of the unaffected peripheral area. The mechanisms underlying this phenomenon are described in a mouse model of unilateral whisker deprivation. Stimulation of intact whiskers yields a bilateral blood-oxygen-level−dependent fMRI response in somatosensory barrel cortex. Whole-cell electrophysiology demonstrated that the intact barrel cortex selectively strengthens callosal synapses to layer 5 neurons in the deprived cortex. These synapses have larger AMPA receptor- and NMDA receptor-mediated events. These factors contribute to a maximally potentiated callosal synapse. This potentiation occludes long-term potentiation, which could be rescued, to some extent, with prior long-term depression induction. Excitability and excitation/inhibition balance were altered in a manner consistent with cell-specific callosal changes and support a shift in the overall state of the cortex. This is a demonstration of a cell-specific, synaptic mechanism underlying interhemispheric cortical reorganization.
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17
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Castaño-Castaño S, Martinez-Navarrete G, Morales-Navas M, Fernández-Jover E, Sanchez-Santed F, Nieto-Escámez F. Transcranial direct-current stimulation (tDCS) improves detection of simple bright stimuli by amblyopic Long Evans rats in the SLAG task and produces an increase of parvoalbumin labelled cells in visual cortices. Brain Res 2019; 1704:94-102. [PMID: 30287342 DOI: 10.1016/j.brainres.2018.09.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 09/21/2018] [Accepted: 09/30/2018] [Indexed: 12/18/2022]
Abstract
In this work visual functional improvement of amblyopic Long Evans rats treated with tDCS has been assessed using the "slow angled-descent forepaw grasping" (SLAG) test. This test is based on an innate response that does not requires any memory-learning component and has been used before for measuring visual function in rodents. The results obtained show that this procedure is useful to assess monocular but not binocular deficits, as controls and amblyopic animals showed significant differences during monocular but not during binocular assessment. On the other hand, parvoalbumin labelling was analysed in three areas of the visual cortex (V1M, V1B and V2L) before and after tDCS treatment. No changes in labelling were observed after monocular deprivation. However, tDCS treatment significantly improved vision through the amblyopic eye, and a significant increase of parvoalbumin-positive cells was observed in the three areas, both in the stimulated hemisphere but also in the non-stimulated hemisphere. This effect occurred both in control and amblyopic animals. Thus, tDCS induced changes are similar in controls and amblyopic animals, although only the last one showed a functional improvement.
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Affiliation(s)
- S Castaño-Castaño
- Universidad de Almería, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada de San Urbano, Almería, Spain; Achucarro, Basque Center for Neuroscience Science Park, edificio de la Sede UPV/EHU, 48940 Leioa, Spain
| | - G Martinez-Navarrete
- Universidad Miguel Hernández de Elche, Unidad de Neuroprótesis y Rehabilitación Visual, Av. de la Universidad S/N, Elche, Alicante, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain
| | - M Morales-Navas
- Universidad de Almería, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada de San Urbano, Almería, Spain
| | - E Fernández-Jover
- Universidad Miguel Hernández de Elche, Unidad de Neuroprótesis y Rehabilitación Visual, Av. de la Universidad S/N, Elche, Alicante, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain
| | - F Sanchez-Santed
- Universidad de Almería, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada de San Urbano, Almería, Spain
| | - F Nieto-Escámez
- Universidad de Almería, Departamento de Psicología, Ctra. Sacramento S/N, 04120, La Cañada de San Urbano, Almería, Spain; Centro de Evaluación y Rehabilitación Neuropsicológica (CERNEP), Ctra. Sacramento S/N, 04120, La Cañada de San Urbano, Almería, Spain
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18
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Lee KS, Vandemark K, Mezey D, Shultz N, Fitzpatrick D. Functional Synaptic Architecture of Callosal Inputs in Mouse Primary Visual Cortex. Neuron 2019; 101:421-428.e5. [PMID: 30658859 DOI: 10.1016/j.neuron.2018.12.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/25/2018] [Accepted: 12/04/2018] [Indexed: 11/30/2022]
Abstract
Callosal projections are thought to play a critical role in coordinating neural activity between the cerebral hemispheres in placental mammals, but the rules that govern the arrangement of callosal synapses on the dendrites of their target neurons remain poorly understood. Here we describe a high-throughput method to map the functional organization of callosal connectivity by combining in vivo 3D random-access two-photon calcium imaging of the dendritic spines of single V1 neurons with optogenetic stimulation of the presynaptic neural population in the contralateral hemisphere. We find that callosal-recipient spines are more likely to cluster with non-callosal-recipient spines with similar orientation preference. These observations, based on optogenetic stimulation, were confirmed by direct anatomical visualization of callosal synaptic connections using post hoc expansion microscopy. Our results demonstrate, for the first time, that functional synaptic clustering in a short dendritic segment could play a role in integrating distinct neuronal circuits.
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Affiliation(s)
- Kuo-Sheng Lee
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA; Integrative Biology and Neuroscience Graduate Program, Florida Atlantic University, Jupiter, FL 33458, USA; International Max Planck Research School for Brain and Behavior, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Kaeli Vandemark
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Dávid Mezey
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Nicole Shultz
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - David Fitzpatrick
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA.
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19
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Bocci T, Nasini F, Caleo M, Restani L, Barloscio D, Ardolino G, Priori A, Maffei L, Nardi M, Sartucci F. Unilateral Application of Cathodal tDCS Reduces Transcallosal Inhibition and Improves Visual Acuity in Amblyopic Patients. Front Behav Neurosci 2018; 12:109. [PMID: 29896093 PMCID: PMC5986963 DOI: 10.3389/fnbeh.2018.00109] [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: 02/28/2018] [Accepted: 05/09/2018] [Indexed: 12/12/2022] Open
Abstract
Objective: Amblyopia is a neurodevelopmental disorder characterized by visual acuity and contrast sensitivity loss, refractory to pharmacological and optical treatments in adulthood. In animals, the corpus callosum (CC) contributes to suppression of visual responses of the amblyopic eye. To investigate the role of interhemispheric pathways in amblyopic patients, we studied the response of the visual cortex to transcranial Direct Current Stimulation (tDCS) applied over the primary visual area (V1) contralateral to the “lazy eye.” Methods: Visual acuity (logMAR) was assessed before (T0), immediately after (T1) and 60’ following the application of cathodal tDCS (2.0 mA, 20’) in 12 amblyopic patients. At each time point, Visual Evoked Potentials (VEPs) triggered by grating stimuli of different contrasts (K90%, K20%) were recorded in both hemispheres and compared to those obtained in healthy volunteers. Results: Cathodal tDCS improved visual acuity respect to baseline (p < 0.0001), whereas sham polarization had no significant effect. At T1, tDCS induced an inhibitory effect on VEPs amplitudes at all contrasts in the targeted side and a facilitation of responses in the hemisphere ipsilateral to the amblyopic eye; compared with controls, the facilitation persisted at T2 for high contrasts (K90%; Holm–Sidak post hoc method, p < 0.001), while the stimulated hemisphere recovered more quickly from inhibition (Holm–Sidak post hoc method, p < 0.001). Conclusions: tDCS is a promising treatment for amblyopia in adults. The rapid recovery of excitability and the concurrent transcallosal disinhibition following perturbation of cortical activity may support a critical role of interhemispheric balance in the pathophysiology of amblyopia.
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Affiliation(s)
- Tommaso Bocci
- Section of Neurophysiopathology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Clinical Center for Neurotechnologies, Neuromodulation, and Movement Disorders, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesco Nasini
- Department of Surgical, Medical, and Molecular Pathology and Critical Care, University of Pisa, Pisa, Italy
| | - Matteo Caleo
- CNR Institute of Neuroscience, University of Pisa, Pisa, Italy
| | - Laura Restani
- CNR Institute of Neuroscience, University of Pisa, Pisa, Italy
| | - Davide Barloscio
- Section of Neurophysiopathology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Gianluca Ardolino
- Clinical Center for Neurotechnologies, Neuromodulation, and Movement Disorders, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Alberto Priori
- Clinical Center for Neurotechnologies, Neuromodulation, and Movement Disorders, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, Milan, Italy.,Department of Health Sciences, University of Milan and Ospedale San Paolo, Milan, Italy
| | - Lamberto Maffei
- CNR Institute of Neuroscience, University of Pisa, Pisa, Italy
| | - Marco Nardi
- Department of Surgical, Medical, and Molecular Pathology and Critical Care, University of Pisa, Pisa, Italy
| | - Ferdinando Sartucci
- Section of Neurophysiopathology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,CNR Institute of Neuroscience, University of Pisa, Pisa, Italy
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20
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Sergeeva EG, Espinosa-Garcia C, Atif F, Pardue MT, Stein DG. Neurosteroid allopregnanolone reduces ipsilateral visual cortex potentiation following unilateral optic nerve injury. Exp Neurol 2018; 306:138-148. [PMID: 29729249 DOI: 10.1016/j.expneurol.2018.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/06/2018] [Accepted: 05/01/2018] [Indexed: 10/17/2022]
Abstract
In adult mice with unilateral optic nerve crush injury (ONC), we studied visual response plasticity in the visual cortex following stimulation with sinusoidal grating. We examined visually evoked potentials (VEP) in the primary visual cortex ipsilateral and contralateral to the crushed nerve. We found that unilateral ONC induces enhancement of visual response on the side ipsilateral to the injury that is evoked by visual stimulation to the intact eye. This enhancement was associated with supranormal spatial frequency thresholds in the intact eye when tested using optomotor response. To probe whether injury-induced disinhibition caused the potentiation, we treated animals with the neurosteroid allopregnanolone, a potent agonist of the GABAA receptor, one hour after crush and on post-injury days 3, 8, 13, and 18. Allopregnanolone diminished enhancement of the VEP and this effect was associated with the upregulated synthesis of the δ-subunit of the GABAA receptor. Our study shows a new aspect of experience-dependent plasticity following unilateral ONC. This hyper-activity in the ipsilateral visual cortex is prevented by upregulation of GABA inhibition with allopregnanolone. Our findings suggest the therapeutic potential of allopregnanolone for modulation of plasticity in certain eye and brain disorders and a possible role for disinhibition in ipsilateral hyper-activity following unilateral ONC.
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Affiliation(s)
- Elena G Sergeeva
- Department of Emergency Medicine, Emory University, 1365B Clifton Road NE, Suite 5100, Atlanta, GA 30322, USA.
| | - Claudia Espinosa-Garcia
- Department of Emergency Medicine, Emory University, 1365B Clifton Road NE, Suite 5100, Atlanta, GA 30322, USA
| | - Fahim Atif
- Department of Emergency Medicine, Emory University, 1365B Clifton Road NE, Suite 5100, Atlanta, GA 30322, USA
| | - Machelle T Pardue
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, 1670 Clairmont Road, Decatur, GA 30033, USA; Department of Biomedical Engineering, Georgia Institute of Technology, 313 Ferst Drive, Atlanta, GA 30332, USA
| | - Donald G Stein
- Department of Emergency Medicine, Emory University, 1365B Clifton Road NE, Suite 5100, Atlanta, GA 30322, USA.
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21
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Conde-Ocazionez SA, Jungen C, Wunderle T, Eriksson D, Neuenschwander S, Schmidt KE. Callosal Influence on Visual Receptive Fields Has an Ocular, an Orientation-and Direction Bias. Front Syst Neurosci 2018; 12:11. [PMID: 29713267 PMCID: PMC5911488 DOI: 10.3389/fnsys.2018.00011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 03/20/2018] [Indexed: 11/30/2022] Open
Abstract
One leading hypothesis on the nature of visual callosal connections (CC) is that they replicate features of intrahemispheric lateral connections. However, CC act also in the central part of the binocular visual field. In agreement, early experiments in cats indicated that they provide the ipsilateral eye part of binocular receptive fields (RFs) at the vertical midline (Berlucchi and Rizzolatti, 1968), and play a key role in stereoscopic function. But until today callosal inputs to receptive fields activated by one or both eyes were never compared simultaneously, because callosal function has been often studied by cutting or lesioning either corpus callosum or optic chiasm not allowing such a comparison. To investigate the functional contribution of CC in the intact cat visual system we recorded both monocular and binocular neuronal spiking responses and receptive fields in the 17/18 transition zone during reversible deactivation of the contralateral hemisphere. Unexpectedly from many of the previous reports, we observe no change in ocular dominance during CC deactivation. Throughout the transition zone, a majority of RFs shrink, but several also increase in size. RFs are significantly more affected for ipsi- as opposed to contralateral stimulation, but changes are also observed with binocular stimulation. Noteworthy, RF shrinkages are tiny and not correlated to the profound decreases of monocular and binocular firing rates. They depend more on orientation and direction preference than on eccentricity or ocular dominance of the receiving neuron's RF. Our findings confirm that in binocularly viewing mammals, binocular RFs near the midline are constructed via the direct geniculo-cortical pathway. They also support the idea that input from the two eyes complement each other through CC: Rather than linking parts of RFs separated by the vertical meridian, CC convey a modulatory influence, reflecting the feature selectivity of lateral circuits, with a strong cardinal bias.
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Affiliation(s)
| | - Christiane Jungen
- Department of Cardiology and Electrophysiology, University Heart Centre, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Wunderle
- Ernst Strüngmann Institute for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany
| | - David Eriksson
- Albert-Ludwigs-University of Freiburg, Freiburg, Germany
| | | | - Kerstin E. Schmidt
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
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22
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Spalletti C, Alia C, Lai S, Panarese A, Conti S, Micera S, Caleo M. Combining robotic training and inactivation of the healthy hemisphere restores pre-stroke motor patterns in mice. eLife 2017; 6:28662. [PMID: 29280732 PMCID: PMC5762156 DOI: 10.7554/elife.28662] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 12/22/2017] [Indexed: 11/13/2022] Open
Abstract
Focal cortical stroke often leads to persistent motor deficits, prompting the need for more effective interventions. The efficacy of rehabilitation can be increased by ‘plasticity-stimulating’ treatments that enhance experience-dependent modifications in spared areas. Transcallosal pathways represent a promising therapeutic target, but their role in post-stroke recovery remains controversial. Here, we demonstrate that the contralesional cortex exerts an enhanced interhemispheric inhibition over the perilesional tissue after focal cortical stroke in mouse forelimb motor cortex. Accordingly, we designed a rehabilitation protocol combining intensive, repeatable exercises on a robotic platform with reversible inactivation of the contralesional cortex. This treatment promoted recovery in general motor tests and in manual dexterity with remarkable restoration of pre-lesion movement patterns, evaluated by kinematic analysis. Recovery was accompanied by a reduction of transcallosal inhibition and ‘plasticity brakes’ over the perilesional tissue. Our data support the use of combinatorial clinical therapies exploiting robotic devices and modulation of interhemispheric connectivity.
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Affiliation(s)
| | - Claudia Alia
- CNR Neuroscience Institute, Pisa, Italy.,Scuola Normale Superiore, Pisa, Italy
| | - Stefano Lai
- Scuola Superiore Sant'Anna, Translational Neural Engineering Area, The BioRobotics Institute, Pontedera, Italy
| | - Alessandro Panarese
- Scuola Superiore Sant'Anna, Translational Neural Engineering Area, The BioRobotics Institute, Pontedera, Italy
| | - Sara Conti
- Scuola Superiore Sant'Anna, Translational Neural Engineering Area, The BioRobotics Institute, Pontedera, Italy
| | - Silvestro Micera
- Scuola Superiore Sant'Anna, Translational Neural Engineering Area, The BioRobotics Institute, Pontedera, Italy.,Bertarelli Foundation Chair in Translational NeuroEngineering Laboratory, Ecole Polytechnique Federale de Lausanne (EPFL), Center for Neuroprosthetics and Institute of Bioengineering, Lausanne, Switzerland
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23
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Hakon J, Quattromani MJ, Sjölund C, Tomasevic G, Carey L, Lee JM, Ruscher K, Wieloch T, Bauer AQ. Multisensory stimulation improves functional recovery and resting-state functional connectivity in the mouse brain after stroke. NEUROIMAGE-CLINICAL 2017; 17:717-730. [PMID: 29264113 PMCID: PMC5726755 DOI: 10.1016/j.nicl.2017.11.022] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/27/2017] [Accepted: 11/23/2017] [Indexed: 10/25/2022]
Abstract
Stroke causes direct structural damage to local brain networks and indirect functional damage to distant brain regions. Neuroplasticity after stroke involves molecular changes within perilesional tissue that can be influenced by regions functionally connected to the site of injury. Spontaneous functional recovery can be enhanced by rehabilitative strategies, which provides experience-driven cell signaling in the brain that enhances plasticity. Functional neuroimaging in humans and rodents has shown that spontaneous recovery of sensorimotor function after stroke is associated with changes in resting-state functional connectivity (RS-FC) within and across brain networks. At the molecular level, GABAergic inhibitory interneurons can modulate brain plasticity in peri-infarct and remote brain regions. Among this cell-type, a decrease in parvalbumin (PV)-immunoreactivity has been associated with improved behavioral outcome. Subjecting rodents to multisensory stimulation through exposure to an enriched environment (EE) enhances brain plasticity and recovery of function after stroke. Yet, how multisensory stimulation relates to RS-FC has not been determined. In this study, we investigated the effect of EE on recovery of RS-FC and behavior in mice after stroke, and if EE-related changes in RS-FC were associated with levels of PV-expressing neurons. Photothrombotic stroke was induced in the sensorimotor cortex. Beginning 2 days after stroke, mice were housed in either standard environment (STD) or EE for 12 days. Housing in EE significantly improved lost tactile-proprioceptive function compared to mice housed in STD environment. RS-FC in the mouse was measured by optical intrinsic signal imaging 14 days after stroke or sham surgery. Stroke induced a marked reduction in RS-FC within several perilesional and remote brain regions. EE partially restored interhemispheric homotopic RS-FC between spared motor regions, particularly posterior secondary motor. Compared to mice housed in STD cages, EE exposure lead to increased RS-FC between posterior secondary motor regions and contralesional posterior parietal and retrosplenial regions. The increased regional RS-FC observed in EE mice after stroke was significantly correlated with decreased PV-immunoreactivity in the contralesional posterior motor region. In conclusion, experimental stroke and subsequent housing in EE induces dynamic changes in RS-FC in the mouse brain. Multisensory stimulation associated with EE enhances RS-FC among distinct brain regions relevant for recovery of sensorimotor function and controlled movements that may involve PV/GABA interneurons. Our results indicate that targeting neural circuitry involving spared motor regions across hemispheres by neuromodulation and multimodal sensory stimulation could improve rehabilitation after stroke.
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Key Words
- EE, enriched environment
- Enriched environment
- GSR, global signal regression
- M1, primary motor cortex
- M2, secondary motor cortex
- M2p, posterior secondary motor cortex
- MSR, multiple signal regression
- NDc, interhemispheric (contralateral) node degree
- NDi, intrahemispheric node degree
- Optical imaging
- PP, posterior parietal cortex
- PV, parvalbumin
- Parvalbumin
- ROI, region of interest
- RS, retrosplenial cortex
- RS-FC, resting-state functional connectivity
- Recovery
- Resting-state functional connectivity
- SFL, somatosensory forelimb cortex
- STD, standard environment
- Stroke
- VIS, visual cortex
- fcOIS, functional connectivity optical intrinsic signal imaging
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Affiliation(s)
- Jakob Hakon
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, 22184 Lund, Sweden.
| | - Miriana Jlenia Quattromani
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, 22184 Lund, Sweden
| | - Carin Sjölund
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, 22184 Lund, Sweden
| | - Gregor Tomasevic
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, 22184 Lund, Sweden; Department of Neurosurgery, University Hospital of Lund, Lund, Sweden
| | - Leeanne Carey
- School of Allied Health, La Trobe University, Melbourne, Vic., Australia; Neurorehabilitation and Recovery Laboratory, Florey Institute of Neuroscience and Mental Health, Melbourne, Vic., Australia
| | - Jin-Moo Lee
- Department of Radiology, Washington University, Saint Louis, MO 63110, USA; Department of Neurology, Washington University, Saint Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University, Saint Louis, MO 63110, USA
| | - Karsten Ruscher
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, 22184 Lund, Sweden
| | - Tadeusz Wieloch
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, 22184 Lund, Sweden
| | - Adam Q Bauer
- Department of Radiology, Washington University, Saint Louis, MO 63110, USA
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Visual experience sculpts whole-cortex spontaneous infraslow activity patterns through an Arc-dependent mechanism. Proc Natl Acad Sci U S A 2017; 114:E9952-E9961. [PMID: 29087327 DOI: 10.1073/pnas.1711789114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Decades of work in experimental animals has established the importance of visual experience during critical periods for the development of normal sensory-evoked responses in the visual cortex. However, much less is known concerning the impact of early visual experience on the systems-level organization of spontaneous activity. Human resting-state fMRI has revealed that infraslow fluctuations in spontaneous activity are organized into stereotyped spatiotemporal patterns across the entire brain. Furthermore, the organization of spontaneous infraslow activity (ISA) is plastic in that it can be modulated by learning and experience, suggesting heightened sensitivity to change during critical periods. Here we used wide-field optical intrinsic signal imaging in mice to examine whole-cortex spontaneous ISA patterns. Using monocular or binocular visual deprivation, we examined the effects of critical period visual experience on the development of ISA correlation and latency patterns within and across cortical resting-state networks. Visual modification with monocular lid suturing reduced correlation between left and right cortices (homotopic correlation) within the visual network, but had little effect on internetwork correlation. In contrast, visual deprivation with binocular lid suturing resulted in increased visual homotopic correlation and increased anti-correlation between the visual network and several extravisual networks, suggesting cross-modal plasticity. These network-level changes were markedly attenuated in mice with genetic deletion of Arc, a gene known to be critical for activity-dependent synaptic plasticity. Taken together, our results suggest that critical period visual experience induces global changes in spontaneous ISA relationships, both within the visual network and across networks, through an Arc-dependent mechanism.
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25
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Griffen TC, Haley MS, Fontanini A, Maffei A. Rapid plasticity of visually evoked responses in rat monocular visual cortex. PLoS One 2017; 12:e0184618. [PMID: 28910338 PMCID: PMC5598998 DOI: 10.1371/journal.pone.0184618] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/28/2017] [Indexed: 11/19/2022] Open
Abstract
Sensory cortical circuits are shaped by experience during sensitive periods in development. In the primary visual cortex (V1) altered visual experience results in changes in visual responsiveness of cortical neurons. The experience-dependent refinement of the circuit in V1 is thought to rely on competitive interactions between feedforward circuits driven by the two eyes. However, recent data have provided evidence for an additional role of cortico-cortical circuits in this process. Indeed, experience-dependent changes in intracortical circuits can be induced rapidly and may result in rapid-onset functional changes. Unilateral occlusion of vision rapidly alters visual responsiveness, synaptic strength and connectivity of local circuits in the binocular region of V1 (V1b), where the inputs from the two eyes converge. In the monocular region of rodent V1 (V1m), where feedforward inputs from the ipsilateral eye are virtually absent, visual deprivation induces rapid plasticity in local circuits; however, functional changes seem to occur only after long periods of deprivation. In V1m there is currently no evidence for functional changes occurring within a time window compatible with that of local circuit plasticity. Here, we probed the visual responsiveness of neurons in rat V1m and assessed the effect of one day unilateral eye lid suture on single neuron visual responses. We report a novel form of plasticity within V1m that occurs on a timescale consistent with the earliest known changes in synaptic strength. Our data provide new insights into how sensory experience can rapidly modulate neuronal responses, even in the absence of direct competition between feedforward thalamocortical inputs.
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Affiliation(s)
- Trevor C. Griffen
- Program in Neuroscience, Stony Brook University, Stony Brook, New York, United States of America
- SUNY Eye Institute, Syracuse, New York, United States of America
- Medical Scientist Training Program, Stony Brook University, Stony Brook, New York, United States of America
| | - Melissa S. Haley
- Program in Neuroscience, Stony Brook University, Stony Brook, New York, United States of America
| | - Alfredo Fontanini
- Program in Neuroscience, Stony Brook University, Stony Brook, New York, United States of America
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, New York, United States of America
| | - Arianna Maffei
- Program in Neuroscience, Stony Brook University, Stony Brook, New York, United States of America
- SUNY Eye Institute, Syracuse, New York, United States of America
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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26
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Žiak P, Holm A, Halička J, Mojžiš P, Piñero DP. Amblyopia treatment of adults with dichoptic training using the virtual reality oculus rift head mounted display: preliminary results. BMC Ophthalmol 2017; 17:105. [PMID: 28659140 PMCID: PMC5490155 DOI: 10.1186/s12886-017-0501-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 06/20/2017] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The gold standard treatments in amblyopia are penalizing therapies, such as patching or blurring vision with atropine that are aimed at forcing the use of the amblyopic eye. However, in the last years, new therapies are being developed and validated, such as dichoptic visual training, aimed at stimulating the amblyopic eye and eliminating the interocular supression. PURPOSE To evaluate the effect of dichoptic visual training using a virtual reality head mounted display in a sample of anisometropic amblyopic adults and to evaluate the potential usefulness of this option of treatment. METHODS A total of 17 subjects (10 men, 7 women) with a mean age of 31.2 years (range, 17-69 year) and anisometropic amblyopia were enrolled. Best corrected visual acuity (BCVA) and stereoacuity (Stereo Randot graded circle test) changes were evaluated after 8 sessions (40 min per session) of dichoptic training with the computer game Diplopia Game (Vivid Vision) run in the Oculus Rift OC DK2 virtual reality head mounted display (Oculus VR). RESULTS Mean BCVA in amblyopic eye improved significantly from a logMAR value of 0.58 ± 0.35 before training to a post-training value of 0.43 ± 0.38 (p < 0.01). Forty-seven percent of the participants achieved BCVA of 20/40 or better after the training as compared to 30% before the training. Mean stereoacuity changed from a value of 263.3 ± 135.1 before dichoptic training to a value of 176.7 ± 152.4 s of arc after training (p < 0.01). A total of 8 patients (47.1%) before dichoptic treatment had unmeasurable stereoacuity while this only occurred in 2 patients (11.8%) after training. CONCLUSIONS Dichoptic training using a virtual reality head mounted display seems to be an effective option of treatment in adults with anisometropic amblyopia. Future clinical trials are needed to confirm this preliminary evidence. TRIAL REGISTRATION Trial ID: ISRCTN62086471 . Date registered: 13/06/2017. Retrospectively registered.
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Affiliation(s)
- Peter Žiak
- Eye clinic, Jessenius faculty of Medicine in Martin, Commenius University in Bratislava, Bratislava, Slovakia
- UVEA Mediklinik, Martin, Slovakia
| | - Anders Holm
- Eye clinic, Jessenius faculty of Medicine in Martin, Commenius University in Bratislava, Bratislava, Slovakia
- UVEA Mediklinik, Martin, Slovakia
| | - Juraj Halička
- Eye clinic, Jessenius faculty of Medicine in Martin, Commenius University in Bratislava, Bratislava, Slovakia
- UVEA Mediklinik, Martin, Slovakia
| | | | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
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27
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Castaño-Castaño S, Garcia-Moll A, Morales-Navas M, Fernandez E, Sanchez-Santed F, Nieto-Escamez F. Transcranial direct current stimulation improves visual acuity in amblyopic Long-Evans rats. Brain Res 2017; 1657:340-346. [DOI: 10.1016/j.brainres.2017.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 11/28/2016] [Accepted: 01/01/2017] [Indexed: 10/20/2022]
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28
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Alia C, Spalletti C, Lai S, Panarese A, Micera S, Caleo M. Reducing GABA A-mediated inhibition improves forelimb motor function after focal cortical stroke in mice. Sci Rep 2016; 6:37823. [PMID: 27897203 PMCID: PMC5126677 DOI: 10.1038/srep37823] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 10/21/2016] [Indexed: 11/25/2022] Open
Abstract
A deeper understanding of post-stroke plasticity is critical to devise more effective pharmacological and rehabilitative treatments. The GABAergic system is one of the key modulators of neuronal plasticity, and plays an important role in the control of “critical periods” during brain development. Here, we report a key role for GABAergic inhibition in functional restoration following ischemia in the adult mouse forelimb motor cortex. After stroke, the majority of cortical sites in peri-infarct areas evoked simultaneous movements of forelimb, hindlimb and tail, consistent with a loss of inhibitory signalling. Accordingly, we found a delayed decrease in several GABAergic markers that accompanied cortical reorganization. To test whether reductions in GABAergic signalling were causally involved in motor improvements, we treated animals during an early post-stroke period with a benzodiazepine inverse agonist, which impairs GABAA receptor function. We found that hampering GABAA signalling led to significant restoration of function in general motor tests (i.e., gridwalk and pellet reaching tasks), with no significant impact on the kinematics of reaching movements. Improvements were persistent as they remained detectable about three weeks after treatment. These data demonstrate a key role for GABAergic inhibition in limiting motor improvements after cortical stroke.
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Affiliation(s)
- Claudia Alia
- Scuola Normale Superiore, 56126, Pisa, Italy.,CNR Neuroscience Institute, 56124, Pisa, Italy
| | | | - Stefano Lai
- The BioRobotics Institute Scuola Superiore Sant'Anna, 56025, Pontedera (PI), Italy
| | - Alessandro Panarese
- The BioRobotics Institute Scuola Superiore Sant'Anna, 56025, Pontedera (PI), Italy
| | - Silvestro Micera
- The BioRobotics Institute Scuola Superiore Sant'Anna, 56025, Pontedera (PI), Italy.,Ecole Polytechnique Federale de Lausanne (EPFL), Bertarelli Foundation Chair in Translational NeuroEngineering Laboratory, Center for Neuroprosthetics and Institute of Bioengineering, CH-1015 Lausanne, Switzerland
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29
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Restani L, Caleo M. Reorganization of Visual Callosal Connections Following Alterations of Retinal Input and Brain Damage. Front Syst Neurosci 2016; 10:86. [PMID: 27895559 PMCID: PMC5107575 DOI: 10.3389/fnsys.2016.00086] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 10/25/2016] [Indexed: 01/16/2023] Open
Abstract
Vision is a very important sensory modality in humans. Visual disorders are numerous and arising from diverse and complex causes. Deficits in visual function are highly disabling from a social point of view and in addition cause a considerable economic burden. For all these reasons there is an intense effort by the scientific community to gather knowledge on visual deficit mechanisms and to find possible new strategies for recovery and treatment. In this review, we focus on an important and sometimes neglected player of the visual function, the corpus callosum (CC). The CC is the major white matter structure in the brain and is involved in information processing between the two hemispheres. In particular, visual callosal connections interconnect homologous areas of visual cortices, binding together the two halves of the visual field. This interhemispheric communication plays a significant role in visual cortical output. Here, we will first review the essential literature on the physiology of the callosal connections in normal vision. The available data support the view that the callosum contributes to both excitation and inhibition to the target hemisphere, with a dynamic adaptation to the strength of the incoming visual input. Next, we will focus on data showing how callosal connections may sense visual alterations and respond to the classical paradigm for the study of visual plasticity, i.e., monocular deprivation (MD). This is a prototypical example of a model for the study of callosal plasticity in pathological conditions (e.g., strabismus and amblyopia) characterized by unbalanced input from the two eyes. We will also discuss the findings of callosal alterations in blind subjects. Noteworthy, we will discuss data showing that inter-hemispheric transfer mediates recovery of visual responsiveness following cortical damage. Finally, we will provide an overview of how callosal projections dysfunction could contribute to pathologies such as neglect and occipital epilepsy. A particular focus will be on reviewing noninvasive brain stimulation techniques and optogenetic approaches that allow to selectively manipulate callosal function and to probe its involvement in cortical processing and plasticity. Overall, the data indicate that experience can potently impact on transcallosal connectivity, and that the callosum itself is crucial for plasticity and recovery in various disorders of the visual pathway.
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Affiliation(s)
- Laura Restani
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy
| | - Matteo Caleo
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy
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30
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Altered recovery from inhibitory repetitive transcranial magnetic stimulation (rTMS) in subjects with photosensitive epilepsy. Clin Neurophysiol 2016; 127:3353-61. [PMID: 27407061 DOI: 10.1016/j.clinph.2016.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 06/08/2016] [Accepted: 06/18/2016] [Indexed: 01/07/2023]
Abstract
OBJECTIVE To investigate functional changes underlying photosensitivity, we studied the response of the visual cortex to low-frequency, inhibitory repetitive transcranial magnetic stimulation (rTMS) in drug-free patients with photosensitive seizures and healthy volunteers. METHODS Visual evoked potentials (VEPs) triggered by grating stimuli of different contrasts were recorded in both hemispheres before and after transient functional inactivation of the occipital cortex of one side via low-frequency rTMS (0.5Hz for 20'). VEPs were recorded before (T0), immediately after (T1) and 45' following the completion of rTMS (T2). RESULTS Baseline amplitudes of the early VEP components (N1 and P1) were enhanced in photosensitive patients. At T1, rTMS produced an inhibitory effect on VEPs amplitudes at all contrasts in the targeted side and a concurrent facilitation of responses in the contralateral hemisphere. Compared with PSE subjects, VEP amplitudes remained persistently dampened in the stimulated hemisphere of controls (Holm-Sidak post-hoc method, p<0.05). In the contralateral hemisphere, we found a clear enhancement of VEP amplitude in photosensitive subjects but not controls at T2 (Holm-Sidak test, p<0.001). CONCLUSIONS Visual responses recovered more quickly in the stimulated hemisphere, and disinhibition persisted in the contralateral side of photosensitive subjects. SIGNIFICANCE The rapid recovery of excitability and the persistent transcallosal disinhibition following perturbation of cortical activity may play a role in the pathophysiology of photosensitive epilepsy.
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31
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Vannini E, Olimpico F, Middei S, Ammassari-Teule M, de Graaf EL, McDonnell L, Schmidt G, Fabbri A, Fiorentini C, Baroncelli L, Costa M, Caleo M. Electrophysiology of glioma: a Rho GTPase-activating protein reduces tumor growth and spares neuron structure and function. Neuro Oncol 2016; 18:1634-1643. [PMID: 27298309 DOI: 10.1093/neuonc/now114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 04/22/2016] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Glioblastomas are the most aggressive type of brain tumor. A successful treatment should aim at halting tumor growth and protecting neuronal cells to prevent functional deficits and cognitive deterioration. Here, we exploited a Rho GTPase-activating bacterial protein toxin, cytotoxic necrotizing factor 1 (CNF1), to interfere with glioma cell growth in vitro and vivo. We also investigated whether this toxin spares neuron structure and function in peritumoral areas. METHODS We performed a microarray transcriptomic and in-depth proteomic analysis to characterize the molecular changes triggered by CNF1 in glioma cells. We also examined tumor cell senescence and growth in vehicle- and CNF1-treated glioma-bearing mice. Electrophysiological and morphological techniques were used to investigate neuronal alterations in peritumoral cortical areas. RESULTS Administration of CNF1 triggered molecular and morphological hallmarks of senescence in mouse and human glioma cells in vitro. CNF1 treatment in vivo induced glioma cell senescence and potently reduced tumor volumes. In peritumoral areas of glioma-bearing mice, neurons showed a shrunken dendritic arbor and severe functional alterations such as increased spontaneous activity and reduced visual responsiveness. CNF1 treatment enhanced dendritic length and improved several physiological properties of pyramidal neurons, demonstrating functional preservation of the cortical network. CONCLUSIONS Our findings demonstrate that CNF1 reduces glioma volume while at the same time maintaining the physiological and structural properties of peritumoral neurons. These data indicate a promising strategy for the development of more effective antiglioma therapies.
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Affiliation(s)
- Eleonora Vannini
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Francesco Olimpico
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Silvia Middei
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Martine Ammassari-Teule
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Erik L de Graaf
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Liam McDonnell
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Gudula Schmidt
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Alessia Fabbri
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Carla Fiorentini
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Laura Baroncelli
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Mario Costa
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
| | - Matteo Caleo
- CNR Neuroscience Institute, Pisa, Italy (E.V., F.O., L.B., M.C., Mat.C.); CNR Cellular Biology and Neurobiology Institute, Rome, Italy (S.M., M.A.-T.); Fondazione Pisana per la Scienza, Mass Spectrometry and Proteomics, Pisa, Italy (E.L.d.G., L.M.); Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Freiburg, Germany (G.S.); Istituto Superiore di Sanità, Rome, Italy (A.F., C.F.); Scuola Normale Superiore, Pisa, Italy (M.C., Mat.C.)
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32
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He XF, Lan Y, Zhang Q, Liang FY, Luo CM, Xu GQ, Pei Z. GABA-ergic interneurons involved in transcallosal inhibition of the visual cortices in vivo in mice. Physiol Behav 2015; 151:502-8. [PMID: 26318391 DOI: 10.1016/j.physbeh.2015.08.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 08/17/2015] [Accepted: 08/18/2015] [Indexed: 01/17/2023]
Abstract
In the current study we investigated the role of the corpus callosum, particularly the gamma-aminobutyric acid-ergic (GABAergic) projection neurons involved in interhemispheric inhibition (IHI). In order to explore IHI in primary visual cortices, we adopted a protocol whereby we performed a direct current lesion of the unilateral primary visual cortex with or without posterior callosotomy, and used two-photon Ca(2+)in vivo imaging on the opposite unaffected region to detect neural activities in mice. Following this procedure, the numbers of vesicular GABAergic transporters (VGATs) and GABAergic interneurons in the unaffected primary cortex were determined using immunofluorescence staining. Results indicated that following unilateral visual cortical lesioning without callosotomy, the neuronal Ca(2+) activities in the opposite side were significantly increased. However, the neuronal activities of the unaffected visual cortex in animals with unilateral cortical lesion with callosotomy were not significantly different. Additionally, there was no significant difference in the numbers of GABAergic interneurons in the unaffected region between each group, while the number of VGATs in the unaffected region was significantly decreased following unilateral visual cortical lesion without callosotomy, which was unchanged once with callosotomy. Finally, callosotomy alone without cortical lesioning produced no change in neuronal activities, the number of GABAergic interneurons or VGATs. Our results demonstrate that IHI between the homologous primary visual cortices occurs via the corpus callosum, and further indicate the important involvement of long-range GABAergic interneurons in transcallosal inhibition.
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Affiliation(s)
- Xiao-fei He
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yue Lan
- Department of Rehabilitation Medicine, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, China
| | - Qun Zhang
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Feng-yin Liang
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Chuan-ming Luo
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Guang-qing Xu
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
| | - Zhong Pei
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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33
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Ortiz FC, Balia M, Orduz D. A commentary on: "Anti-muscarinic adjunct therapy accelerates functional human oligodendrocyte repair". Front Cell Neurosci 2015; 9:274. [PMID: 26257606 PMCID: PMC4508516 DOI: 10.3389/fncel.2015.00274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/03/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
- Fernando C Ortiz
- Neurophysiology and New Microscopies Laboratory, INSERM U1128, Université Paris Descartes, Sorbonne Paris Cité Paris, France
| | - Maddalena Balia
- Neurophysiology and New Microscopies Laboratory, INSERM U1128, Université Paris Descartes, Sorbonne Paris Cité Paris, France
| | - David Orduz
- Neurophysiology and New Microscopies Laboratory, INSERM U1128, Université Paris Descartes, Sorbonne Paris Cité Paris, France
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34
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Altered sensory processing and dendritic remodeling in hyperexcitable visual cortical networks. Brain Struct Funct 2015; 221:2919-36. [PMID: 26163822 DOI: 10.1007/s00429-015-1080-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 07/01/2015] [Indexed: 01/20/2023]
Abstract
Epilepsy is characterized by impaired circuit function and a propensity for spontaneous seizures, but how plastic rearrangements within the epileptic focus trigger cortical dysfunction and hyperexcitability is only partly understood. Here we have examined alterations in sensory processing and the underlying biochemical and neuroanatomical changes in tetanus neurotoxin (TeNT)-induced focal epilepsy in mouse visual cortex. We documented persistent epileptiform electrographic discharges and upregulation of GABAergic markers at the completion of TeNT effects. We also found a significant remodeling of the dendritic arbors of pyramidal neurons, with increased dendritic length and branching, and overall reduction in spine density but significant preservation of mushroom, mature spines. Functionally, spontaneous neuronal discharge was increased, visual responses were less reliable, and electrophysiological and behavioural visual acuity was consistently impaired in TeNT-injected mice. These data demonstrate robust, long-term remodeling of both inhibitory and excitatory circuitry associated with specific disturbances of network function in neocortical epilepsy.
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35
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Progressive maturation of silent synapses governs the duration of a critical period. Proc Natl Acad Sci U S A 2015; 112:E3131-40. [PMID: 26015564 DOI: 10.1073/pnas.1506488112] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
During critical periods, all cortical neural circuits are refined to optimize their functional properties. The prevailing notion is that the balance between excitation and inhibition determines the onset and closure of critical periods. In contrast, we show that maturation of silent glutamatergic synapses onto principal neurons was sufficient to govern the duration of the critical period for ocular dominance plasticity in the visual cortex of mice. Specifically, postsynaptic density protein-95 (PSD-95) was absolutely required for experience-dependent maturation of silent synapses, and its absence before the onset of critical periods resulted in lifelong juvenile ocular dominance plasticity. Loss of PSD-95 in the visual cortex after the closure of the critical period reinstated silent synapses, resulting in reopening of juvenile-like ocular dominance plasticity. Additionally, silent synapse-based ocular dominance plasticity was largely independent of the inhibitory tone, whose developmental maturation was independent of PSD-95. Moreover, glutamatergic synaptic transmission onto parvalbumin-positive interneurons was unaltered in PSD-95 KO mice. These findings reveal not only that PSD-95-dependent silent synapse maturation in visual cortical principal neurons terminates the critical period for ocular dominance plasticity but also indicate that, in general, once silent synapses are consolidated in any neural circuit, initial experience-dependent functional optimization and critical periods end.
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36
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Dehmel S, Löwel S. Cortico-cortical interactions influence binocularity of the primary visual cortex of adult mice. PLoS One 2014; 9:e105745. [PMID: 25157503 PMCID: PMC4144898 DOI: 10.1371/journal.pone.0105745] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 07/28/2014] [Indexed: 11/18/2022] Open
Abstract
Electrophysiological studies have revealed that a large proportion of the mouse primary visual cortex (V1) receives input also from the ipsilateral eye. This is surprising as most optic nerve fibers cross at the optic chiasm in mice. Inactivating V1 of one hemisphere has recently demonstrated a strong contribution of one hemisphere's activity on binocularity of single units and visually evoked potentials of V1 in the other hemisphere of young rats and of single units in young adult mice. Here we used intrinsic signal optical imaging to quantitatively study the influence of cortico-cortical connections on the magnitude of neuronal activation in the entire binocular zone of adult mouse V1. We simultaneously measured V1-activity of both hemispheres in adult C57BL/6J mice before and after blocking sensory-driven activity in one hemisphere with muscimol. In V1 contralateral to the inactivation, ipsilateral eye evoked activity was reduced by on average 18% while contralateral eye evoked activity did not change. Our results clearly show that cortico-cortical interactions exert a global amplification of ipsilateral eye evoked activity in adult mouse V1.
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Affiliation(s)
- Susanne Dehmel
- Department of Systems Neuroscience, Bernstein Fokus Neurotechnologie, Johann-Friedrich-Blumbach-Institut für Zoologie und Anthropologie, Georg-August-Universität Göttingen, Göttingen, Germany
- Sensory Collaborative Research Center 889, Georg-August-Universität Göttingen, Göttingen, Germany
- * E-mail:
| | - Siegrid Löwel
- Department of Systems Neuroscience, Bernstein Fokus Neurotechnologie, Johann-Friedrich-Blumbach-Institut für Zoologie und Anthropologie, Georg-August-Universität Göttingen, Göttingen, Germany
- Sensory Collaborative Research Center 889, Georg-August-Universität Göttingen, Göttingen, Germany
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Laing RJ, Turecek J, Takahata T, Olavarria JF. Identification of Eye-Specific Domains and Their Relation to Callosal Connections in Primary Visual Cortex of Long Evans Rats. Cereb Cortex 2014; 25:3314-29. [PMID: 24969475 DOI: 10.1093/cercor/bhu128] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ocular dominance columns (ODCs) exist in many primates and carnivores, but it is believed that they do not exist in rodents. Using a combination of transneuronal tracing, in situ hybridization for Zif268 and electrophysiological recordings, we show that inputs from both eyes are largely segregated in the binocular region of V1 in Long Evans rats. We also show that, interposed between this binocular region and the lateral border of V1, there lies a strip of cortex that is strongly dominated by the contralateral eye. Finally, we show that callosal connections colocalize primarily with ipsilateral eye domains in the binocular region and with contralateral eye input in the lateral cortical strip, mirroring the relationship between patchy callosal connections and specific sets of ODCs described previously in the cat. Our results suggest that development of cortical modular architecture is more conserved among rodents, carnivores, and primates than previously thought.
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Affiliation(s)
- R J Laing
- Department of Psychology, and Behavior and Neuroscience Program, University of Washington, Seattle, WA 98195-1525, USA
| | | | - T Takahata
- Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA
| | - J F Olavarria
- Department of Psychology, and Behavior and Neuroscience Program, University of Washington, Seattle, WA 98195-1525, USA
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38
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Vannini E, Panighini A, Cerri C, Fabbri A, Lisi S, Pracucci E, Benedetto N, Vannozzi R, Fiorentini C, Caleo M, Costa M. The bacterial protein toxin, cytotoxic necrotizing factor 1 (CNF1) provides long-term survival in a murine glioma model. BMC Cancer 2014; 14:449. [PMID: 24939046 PMCID: PMC4075618 DOI: 10.1186/1471-2407-14-449] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 06/11/2014] [Indexed: 11/13/2022] Open
Abstract
Background Glioblastomas are largely unresponsive to all available treatments and there is therefore an urgent need for novel therapeutics. Here we have probed the antineoplastic effects of a bacterial protein toxin, the cytotoxic necrotizing factor 1 (CNF1), in the syngenic GL261 glioma cell model. CNF1 produces a long-lasting activation of Rho GTPases, with consequent blockade of cytodieresis in proliferating cells and promotion of neuron health and plasticity. Methods We have tested the antiproliferative effects of CNF1 on GL261 cells and human glioma cells obtained from surgical specimens. For the in vivo experiments, we injected GL261 cells into the adult mouse visual cortex, and five days later we administered either a single intracerebral dose of CNF1 or vehicle. To compare CNF1 with a canonical antitumoral drug, we infused temozolomide (TMZ) via minipumps for 1 week in an additional animal group. Results In culture, CNF1 was very effective in blocking proliferation of GL261 cells, leading them to multinucleation, senescence and death within 15 days. CNF1 had a similar cytotoxic effect in primary human glioma cells. CNF1 also inhibited motility of GL261 cells in a scratch-wound migration assay. Low dose (2 nM) CNF1 and continuous TMZ infusion significantly prolonged animal survival (median survival 35 days vs. 28 days in vehicle controls). Remarkably, increasing CNF1 concentration to 80 nM resulted in a dramatic enhancement of survival with no obvious toxicity. Indeed, 57% of the CNF1-treated animals survived up to 60 days following GL261 glioma cell transplant. Conclusions The activation of Rho GTPases by CNF1 represents a novel potential therapeutic strategy for the treatment of central nervous system tumors.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Matteo Caleo
- CNR Neuroscience Institute, Via Moruzzi 1, 56124 Pisa, Italy.
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Allegra M, Genovesi S, Maggia M, Cenni MC, Zunino G, Sgadò P, Caleo M, Bozzi Y. Altered GABAergic markers, increased binocularity and reduced plasticity in the visual cortex of Engrailed-2 knockout mice. Front Cell Neurosci 2014; 8:163. [PMID: 24987331 PMCID: PMC4060086 DOI: 10.3389/fncel.2014.00163] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 05/29/2014] [Indexed: 01/23/2023] Open
Abstract
The maturation of the GABAergic system is a crucial determinant of cortical development during early postnatal life, when sensory circuits undergo a process of activity-dependent refinement. An altered excitatory/inhibitory balance has been proposed as a possible pathogenic mechanism of autism spectrum disorders (ASD). The homeobox-containing transcription factor Engrailed-2 (En2) has been associated to ASD, and En2 knockout (En2−/−) mice show ASD-like features accompanied by a partial loss of cortical GABAergic interneurons. Here we studied GABAergic markers and cortical function in En2−/− mice, by exploiting the well-known anatomical and functional features of the mouse visual system. En2 is expressed in the visual cortex at postnatal day 30 and during adulthood. When compared to age-matched En2+/+ controls, En2−/− mice showed an increased number of parvalbumin (PV+), somatostatin (SOM+), and neuropeptide Y (NPY+) positive interneurons in the visual cortex at P30, and a decreased number of SOM+ and NPY+ interneurons in the adult. At both ages, the differences in distinct interneuron populations observed between En2+/+ and En2−/− mice were layer-specific. Adult En2−/− mice displayed a normal eye-specific segregation in the retino-geniculate pathway, and in vivo electrophysiological recordings showed a normal development of basic functional properties (acuity, response latency, receptive field size) of the En2−/− primary visual cortex. However, a significant increase of binocularity was found in P30 and adult En2−/− mice, as compared to age-matched controls. Differently from what observed in En2+/+ mice, the En2−/− primary visual cortex did not respond to a brief monocular deprivation performed between P26 and P29, during the so-called “critical period.” These data suggest that altered GABAergic circuits impact baseline binocularity and plasticity in En2−/− mice, while leaving other visual functional properties unaffected.
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Affiliation(s)
- Manuela Allegra
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy ; Laboratory of Neurobiology, Scuola Normale Superiore Pisa, Italy
| | - Sacha Genovesi
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Marika Maggia
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Maria C Cenni
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy
| | - Giulia Zunino
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Paola Sgadò
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Matteo Caleo
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy
| | - Yuri Bozzi
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy ; Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
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40
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Pietrasanta M, Restani L, Cerri C, Olcese U, Medini P, Caleo M. A switch from inter-ocular to inter-hemispheric suppression following monocular deprivation in the rat visual cortex. Eur J Neurosci 2014; 40:2283-92. [PMID: 24689940 DOI: 10.1111/ejn.12573] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 02/04/2014] [Accepted: 02/25/2014] [Indexed: 11/28/2022]
Abstract
Binocularity is a key property of primary visual cortex (V1) neurons that is widely used to study synaptic integration in the brain and plastic mechanisms following an altered visual experience. However, it is not clear how the inputs from the two eyes converge onto binocular neurons, and how their interaction is modified by an unbalanced visual drive. Here, using visual evoked potentials recorded in the juvenile rat V1, we report evidence for a suppressive mechanism by which contralateral eye activity inhibits responses from the ipsilateral eye. Accordingly, we found a lack of additivity of the responses evoked independently by the two eyes in the V1, and acute silencing of the contralateral eye resulted in the enhancement of ipsilateral eye responses in cortical neurons. We reverted the relative cortical strength of the two eyes by suturing the contralateral eye shut [monocular deprivation (MD)]. After 7 days of MD, there was a loss of interocular suppression mediated by the contralateral, deprived eye, and weak inputs from the closed eye were functionally inhibited by interhemispheric callosal pathways. We conclude that interocular suppressive mechanisms play a crucial role in shaping normal binocularity in visual cortical neurons, and a switch from interocular to interhemispheric suppression represents a key step in the ocular dominance changes induced by MD. These data have important implications for a deeper understanding of the key mechanisms that underlie activity-dependent rearrangements of cortical circuits following alteration of sensory experience.
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Affiliation(s)
- Marta Pietrasanta
- CNR Neuroscience Institute, Pisa, Italy; Italian Institute of Technology, Genova, Italy
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41
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Neuronal mechanisms underlying transhemispheric diaschisis following focal cortical injuries. Brain Struct Funct 2014; 220:1649-64. [DOI: 10.1007/s00429-014-0750-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Accepted: 03/03/2014] [Indexed: 12/18/2022]
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Nys J, Aerts J, Ytebrouck E, Vreysen S, Laeremans A, Arckens L. The cross-modal aspect of mouse visual cortex plasticity induced by monocular enucleation is age dependent. J Comp Neurol 2014; 522:950-70. [DOI: 10.1002/cne.23455] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/17/2013] [Accepted: 08/14/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Julie Nys
- Laboratory of Neuroplasticity and Neuroproteomics; KU Leuven; 3000 Leuven Belgium
| | - Jeroen Aerts
- Laboratory of Neuroplasticity and Neuroproteomics; KU Leuven; 3000 Leuven Belgium
| | - Ellen Ytebrouck
- Laboratory of Neuroplasticity and Neuroproteomics; KU Leuven; 3000 Leuven Belgium
| | - Samme Vreysen
- Laboratory of Neuroplasticity and Neuroproteomics; KU Leuven; 3000 Leuven Belgium
| | - Annelies Laeremans
- Laboratory of Neuroplasticity and Neuroproteomics; KU Leuven; 3000 Leuven Belgium
| | - Lutgarde Arckens
- Laboratory of Neuroplasticity and Neuroproteomics; KU Leuven; 3000 Leuven Belgium
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43
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Environmental enrichment extends ocular dominance plasticity into adulthood and protects from stroke-induced impairments of plasticity. Proc Natl Acad Sci U S A 2014; 111:1150-5. [PMID: 24395770 DOI: 10.1073/pnas.1313385111] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ocular dominance (OD) plasticity in mouse primary visual cortex (V1) declines during postnatal development and is absent beyond postnatal day 110 if mice are raised in standard cages (SCs). An enriched environment (EE) promotes OD plasticity in adult rats. Here, we explored cellular mechanisms of EE in mouse V1 and the therapeutic potential of EE to prevent impairments of plasticity after a cortical stroke. Using in vivo optical imaging, we observed that monocular deprivation in adult EE mice (i) caused a very strong OD plasticity previously only observed in 4-wk-old animals, (ii) restored already lost OD plasticity in adult SC-raised mice, and (iii) preserved OD plasticity after a stroke in the primary somatosensory cortex. Using patch-clamp electrophysiology in vitro, we also show that (iv) local inhibition was significantly reduced in V1 slices of adult EE mice and (v) the GABA/AMPA ratio was like that in 4-wk-old SC-raised animals. These observations were corroborated by in vivo analyses showing that diazepam treatment significantly reduced the OD shift of EE mice after monocular deprivation. Taken together, EE extended the sensitive phase for OD plasticity into late adulthood, rejuvenated V1 after 4 mo of SC-rearing, and protected adult mice from stroke-induced impairments of cortical plasticity. The EE effect was mediated most likely by preserving low juvenile levels of inhibition into adulthood, which potentially promoted adaptive changes in cortical circuits.
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44
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Bocci T, Pietrasanta M, Cerri C, Restani L, Caleo M, Sartucci F. Visual callosal connections: role in visual processing in health and disease. Rev Neurosci 2014; 25:113-27. [DOI: 10.1515/revneuro-2013-0025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 09/07/2013] [Indexed: 11/15/2022]
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Ferrari E, Gu C, Niranjan D, Restani L, Rasetti-Escargueil C, Obara I, Geranton SM, Arsenault J, Goetze TA, Harper CB, Nguyen TH, Maywood E, O'Brien J, Schiavo G, Wheeler DW, Meunier FA, Hastings M, Edwardson JM, Sesardic D, Caleo M, Hunt SP, Davletov B. Synthetic self-assembling clostridial chimera for modulation of sensory functions. Bioconjug Chem 2013; 24:1750-9. [PMID: 24011174 PMCID: PMC3901392 DOI: 10.1021/bc4003103] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Clostridial neurotoxins reversibly block neuronal communication for weeks and months. While these proteolytic neurotoxins hold great promise for clinical applications and the investigation of brain function, their paralytic activity at neuromuscular junctions is a stumbling block. To redirect the clostridial activity to neuronal populations other than motor neurons, we used a new self-assembling method to combine the botulinum type A protease with the tetanus binding domain, which natively targets central neurons. The two parts were produced separately and then assembled in a site-specific way using a newly introduced 'protein stapling' technology. Atomic force microscopy imaging revealed dumbbell shaped particles which measure ∼23 nm. The stapled chimera inhibited mechanical hypersensitivity in a rat model of inflammatory pain without causing either flaccid or spastic paralysis. Moreover, the synthetic clostridial molecule was able to block neuronal activity in a defined area of visual cortex. Overall, we provide the first evidence that the protein stapling technology allows assembly of distinct proteins yielding new biomedical properties.
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Affiliation(s)
- Enrico Ferrari
- MRC Laboratory of Molecular Biology , Cambridge, United Kingdom
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Longordo F, To MS, Ikeda K, Stuart GJ. Sublinear integration underlies binocular processing in primary visual cortex. Nat Neurosci 2013; 16:714-23. [PMID: 23644484 DOI: 10.1038/nn.3394] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/08/2013] [Indexed: 12/12/2022]
Abstract
Although we know much about the capacity of neurons to integrate synaptic inputs in vitro, less is known about synaptic integration in vivo. Here we address this issue by investigating the integration of inputs from the two eyes in mouse primary visual cortex. We find that binocular inputs to layer 2/3 pyramidal neurons are integrated sublinearly in an amplitude-dependent manner. Sublinear integration was greatest when binocular responses were largest, as occurs at the preferred orientation and binocular disparity, and highest contrast. Using voltage-clamp experiments and modeling, we show that sublinear integration occurs postsynaptically. The extent of sublinear integration cannot be accounted for solely by nonlinear integration of excitatory inputs, even when they are activated closely in space and time, but requires balanced recruitment of inhibition. Finally, we show that sublinear binocular integration acts as a divisive form of gain control, linearizing the output of binocular neurons and enhancing orientation selectivity.
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Affiliation(s)
- Fabio Longordo
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia.
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Affiliation(s)
- Christiaan N. Levelt
- Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, 1105BA Amsterdam, The Netherlands;
| | - Mark Hübener
- Max Planck Institute of Neurobiology, D-82152 Martinsried, Germany;
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The corpus callosum and the visual cortex: plasticity is a game for two. Neural Plast 2012; 2012:838672. [PMID: 22792494 PMCID: PMC3388387 DOI: 10.1155/2012/838672] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 04/19/2012] [Indexed: 01/03/2023] Open
Abstract
Throughout life, experience shapes and selects the most appropriate brain functional connectivity to adapt to a changing environment. An ideal system to study experience-dependent plasticity is the visual cortex, because visual experience can be easily manipulated. In this paper, we focus on the role of interhemispheric, transcallosal projections in experience-dependent plasticity of the visual cortex. We review data showing that deprivation of sensory experience can modify the morphology of callosal fibres, thus altering the communication between the two hemispheres. More importantly, manipulation of callosal input activity during an early critical period alters developmental maturation of functional properties in visual cortex and modifies its ability to remodel in response to experience. We also discuss recent data in rat visual cortex, demonstrating that the corpus callosum plays a role in binocularity of cortical neurons and is involved in the plastic shift of eye preference that follows a period of monocular eyelid suture (monocular deprivation) in early age. Thus, experience can modify the fine connectivity of the corpus callosum, and callosal connections represent a major pathway through which experience can mediate functional maturation and plastic rearrangements in the visual cortex.
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49
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Tognini P, Manno I, Bonaccorsi J, Cenni MC, Sale A, Maffei L. Environmental enrichment promotes plasticity and visual acuity recovery in adult monocular amblyopic rats. PLoS One 2012; 7:e34815. [PMID: 22509358 PMCID: PMC3324549 DOI: 10.1371/journal.pone.0034815] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 03/05/2012] [Indexed: 11/18/2022] Open
Abstract
Loss of visual acuity caused by abnormal visual experience during development (amblyopia) is an untreatable pathology in adults. In some occasions, amblyopic patients loose vision in their better eye owing to accidents or illnesses. While this condition is relevant both for its clinical importance and because it represents a case in which binocular interactions in the visual cortex are suppressed, it has scarcely been studied in animal models. We investigated whether exposure to environmental enrichment (EE) is effective in triggering recovery of vision in adult amblyopic rats rendered monocular by optic nerve dissection in their normal eye. By employing both electrophysiological and behavioral assessments, we found a full recovery of visual acuity in enriched rats compared to controls reared in standard conditions. Moreover, we report that EE modulates the expression of GAD67 and BDNF. The non invasive nature of EE renders this paradigm promising for amblyopia therapy in adult monocular people.
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Affiliation(s)
- Paola Tognini
- Laboratory of Neurobiology, Scuola Normale Superiore, Pisa, Italy
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Regional and temporal specificity of intrinsic plasticity mechanisms in rodent primary visual cortex. J Neurosci 2012; 31:17932-40. [PMID: 22159108 DOI: 10.1523/jneurosci.4455-11.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Different neocortical regions are functionally specialized, but whether this specialization is reflected in the forms of plasticity present during developmental critical periods (CPs) is largely unknown. In rodent visual cortex, we recently showed that a form of intrinsic plasticity [LTP of intrinsic excitability (LTP-IE)] in the monocular region of the primary visual cortex (V1M) plays an important role in modulating cortical responsiveness following visual deprivation. Here we ask whether LTP-IE is present and similarly regulated by visual experience in the binocular region of the primary visual cortex (V1B), where inputs from the two eyes compete during the CP. In contrast to V1M, where LTP-IE is present throughout the CP, in V1B LTP-IE was only transiently expressed at the onset of the CP. Also distinct from V1M, brief monocular deprivation (MD) was unable to modulate LTP-IE magnitude in V1B, and even binocular deprivation (the equivalent of MD in V1M) could only influence LTP-IE expression during a narrow time window at the peak of the CP. Finally, we asked whether these differences depend on differences in sensory activation of the two areas during development. MD of ipsilateral inputs from before eye opening (to reduce competitive interactions) did not affect the pattern of LTP-IE expression in V1B. Further, the differences in plasticity in the two cortical areas persisted when animals were reared in the dark to remove all patterned visual input. Thus neocortical LTP-IE expression shows dramatic regional and temporal differentiation, and these differences are not driven by differences in sensory experience.
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