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Wu MW, Kourdougli N, Portera-Cailliau C. Network state transitions during cortical development. Nat Rev Neurosci 2024:10.1038/s41583-024-00824-y. [PMID: 38783147 DOI: 10.1038/s41583-024-00824-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2024] [Indexed: 05/25/2024]
Abstract
Mammalian cortical networks are active before synaptogenesis begins in earnest, before neuronal migration is complete, and well before an animal opens its eyes and begins to actively explore its surroundings. This early activity undergoes several transformations during development. The most important of these is a transition from episodic synchronous network events, which are necessary for patterning the neocortex into functionally related modules, to desynchronized activity that is computationally more powerful and efficient. Network desynchronization is perhaps the most dramatic and abrupt developmental event in an otherwise slow and gradual process of brain maturation. In this Review, we summarize what is known about the phenomenology of developmental synchronous activity in the rodent neocortex and speculate on the mechanisms that drive its eventual desynchronization. We argue that desynchronization of network activity is a fundamental step through which the cortex transitions from passive, bottom-up detection of sensory stimuli to active sensory processing with top-down modulation.
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Affiliation(s)
- Michelle W Wu
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Neuroscience Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, CA, USA
- UCLA-Caltech Medical Scientist Training Program, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Nazim Kourdougli
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Carlos Portera-Cailliau
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
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2
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Neuronal membrane proteasomes regulate neuronal circuit activity in vivo and are required for learning-induced behavioral plasticity. Proc Natl Acad Sci U S A 2023; 120:e2216537120. [PMID: 36630455 PMCID: PMC9934054 DOI: 10.1073/pnas.2216537120] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Protein degradation is critical for brain function through processes that remain incompletely understood. Here, we investigated the in vivo function of the 20S neuronal membrane proteasome (NMP) in the brain of Xenopus laevis tadpoles. With biochemistry, immunohistochemistry, and electron microscopy, we demonstrated that NMPs are conserved in the tadpole brain and preferentially degrade neuronal activity-induced newly synthesized proteins in vivo. Using in vivo calcium imaging in the optic tectum, we showed that acute NMP inhibition rapidly increased spontaneous neuronal activity, resulting in hypersynchronization across tectal neurons. At the circuit level, inhibiting NMPs abolished learning-dependent improvement in visuomotor behavior in live animals and caused a significant deterioration in basal behavioral performance following visual training with enhanced visual experience. Our data provide in vivo characterization of NMP functions in the vertebrate nervous system and suggest that NMP-mediated degradation of activity-induced nascent proteins may serve as a homeostatic modulatory mechanism in neurons that is critical for regulating neuronal activity and experience-dependent circuit plasticity.
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3
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Hiramoto M, Cline HT. Tetrode Recording in the Xenopus laevis Visual System Using Multichannel Glass Electrodes. Cold Spring Harb Protoc 2021; 2021:pdb.prot107086. [PMID: 33536286 DOI: 10.1101/pdb.prot107086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Xenopus tadpole visual system shows an extraordinary extent of developmental and visual experience-dependent plasticity, establishing sophisticated neuronal response properties that guide essential survival behaviors. The external development and access to the developing visual circuit of Xenopus tadpoles make them an excellent experimental system in which to elucidate plastic changes in neuronal properties and their capacity to encode information about the visual scene. The temporal structure of neural activity encodes a significant amount of information, access to which requires recording methods with high temporal resolution. Conversely, elucidating changes in the temporal structure of neural activity requires recording over extended periods. It is challenging to maintain patch-clamp recordings over extended periods and Ca2+ imaging has limited temporal resolution. Extracellular recordings have been used in other systems for extended recording; however, spike amplitudes in the developing Xenopus visual circuit are not large enough to be captured by distant electrodes. Here we describe a juxtacellular tetrode recording method for continuous long-term recordings from neurons in intact tadpoles, which can also be exposed to diverse visual stimulation protocols. Electrode position in the tectum is stabilized by the large contact area in the tissue. Contamination of the signal from neighboring neurons is minimized by the tight contact between the glass capillaries and the dense arrangement of neurons in the tectum. This recording method enables analysis of developmental and visual experience-dependent plastic changes in neuronal response properties at higher temporal resolution and over longer periods than current methods.
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Affiliation(s)
- Masaki Hiramoto
- The Dorris Neuroscience Center, Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Hollis T Cline
- The Dorris Neuroscience Center, Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037, USA
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4
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Xie J, Jusuf PR, Bui BV, Goodbourn PT. Experience-dependent development of visual sensitivity in larval zebrafish. Sci Rep 2019; 9:18931. [PMID: 31831839 PMCID: PMC6908733 DOI: 10.1038/s41598-019-54958-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 11/19/2019] [Indexed: 12/25/2022] Open
Abstract
The zebrafish (Danio rerio) is a popular vertebrate model for studying visual development, especially at the larval stage. For many vertebrates, post-natal visual experience is essential to fine-tune visual development, but it is unknown how experience shapes larval zebrafish vision. Zebrafish swim with a moving texture; in the wild, this innate optomotor response (OMR) stabilises larvae in moving water, but it can be exploited in the laboratory to assess zebrafish visual function. Here, we compared spatial-frequency tuning inferred from OMR between visually naïve and experienced larvae from 5 to 7 days post-fertilisation. We also examined development of synaptic connections between neurons by quantifying post-synaptic density 95 (PSD-95) in larval retinae. PSD-95 is closely associated with N-methyl-D-aspartate (NMDA) receptors, the neurotransmitter-receptor proteins underlying experience-dependent visual development. We found that rather than following an experience-independent genetic programme, developmental changes in visual spatial-frequency tuning at the larval stage required visual experience. Exposure to motion evoking OMR yielded no greater improvement than exposure to static form, suggesting that increased sensitivity as indexed by OMR was driven not by motor practice but by visual experience itself. PSD-95 density varied with visual sensitivity, suggesting that experience may have up-regulated clustering of PSD-95 for synaptic maturation in visual development.
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Affiliation(s)
- Jiaheng Xie
- School of Biosciences, The University of Melbourne, Melbourne, Australia
| | - Patricia R Jusuf
- School of Biosciences, The University of Melbourne, Melbourne, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - Patrick T Goodbourn
- Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, Australia.
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5
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Busch SE, Khakhalin AS. Intrinsic temporal tuning of neurons in the optic tectum is shaped by multisensory experience. J Neurophysiol 2019; 122:1084-1096. [PMID: 31291161 DOI: 10.1152/jn.00099.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
For a biological neural network to be functional, its neurons need to be connected with synapses of appropriate strength, and each neuron needs to appropriately respond to its synaptic inputs. This second aspect of network tuning is maintained by intrinsic plasticity; yet it is often considered secondary to changes in connectivity and mostly limited to adjustments of overall excitability of each neuron. Here we argue that even nonoscillatory neurons can be tuned to inputs of different temporal dynamics and that they can routinely adjust this tuning to match the statistics of their synaptic activation. Using the dynamic clamp technique, we show that, in the tectum of Xenopus tadpole, neurons become selective for faster inputs when animals are exposed to fast visual stimuli but remain responsive to longer inputs in animals exposed to slower, looming, or multisensory stimulation. We also report a homeostatic cotuning between synaptic and intrinsic temporal properties of individual tectal cells. These results expand our understanding of intrinsic plasticity in the brain and suggest that there may exist an additional dimension of network tuning that has been so far overlooked.NEW & NOTEWORTHY We use dynamic clamp to show that individual neurons in the tectum of Xenopus tadpoles are selectively tuned to either shorter (more synchronous) or longer (less synchronous) synaptic inputs. We also demonstrate that this intrinsic temporal tuning is strongly shaped by sensory experiences. This new phenomenon, which is likely to be mediated by changes in sodium channel inactivation, is bound to have important consequences for signal processing and the development of local recurrent connections.
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Affiliation(s)
- Silas E Busch
- Biology Program, Bard College, Annandale-on-Hudson, New York
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6
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Pietri T, Romano SA, Pérez-Schuster V, Boulanger-Weill J, Candat V, Sumbre G. The Emergence of the Spatial Structure of Tectal Spontaneous Activity Is Independent of Visual Inputs. Cell Rep 2018; 19:939-948. [PMID: 28467907 PMCID: PMC5437726 DOI: 10.1016/j.celrep.2017.04.015] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 02/15/2017] [Accepted: 04/04/2017] [Indexed: 01/24/2023] Open
Abstract
The brain is spontaneously active, even in the absence of sensory stimulation. The functionally mature zebrafish optic tectum shows spontaneous activity patterns reflecting a functional connectivity adapted for the circuit’s functional role and predictive of behavior. However, neither the emergence of these patterns during development nor the role of retinal inputs in their maturation has been characterized. Using two-photon calcium imaging, we analyzed spontaneous activity in intact and enucleated zebrafish larvae throughout tectum development. At the onset of retinotectal connections, intact larvae showed major changes in the spatiotemporal structure of spontaneous activity. Although the absence of retinal inputs had a significant impact on the development of the temporal structure, the tectum was still capable of developing a spatial structure associated with the circuit’s functional roles and predictive of behavior. We conclude that neither visual experience nor intrinsic retinal activity is essential for the emergence of a spatially structured functional circuit. Development of tectal circuitry is influenced by the onset of retinal inputs Enucleations impact the development of the tectum’s spontaneous activity correlations Enucleations only delay the topography of the correlated activity In the absence of retinal inputs, the tectal circuitry is capable of predicting behavior
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Affiliation(s)
- Thomas Pietri
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Sebastián A Romano
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Verónica Pérez-Schuster
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Jonathan Boulanger-Weill
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Virginie Candat
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Germán Sumbre
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France.
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7
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Avitan L, Pujic Z, Mölter J, Van De Poll M, Sun B, Teng H, Amor R, Scott EK, Goodhill GJ. Spontaneous Activity in the Zebrafish Tectum Reorganizes over Development and Is Influenced by Visual Experience. Curr Biol 2017; 27:2407-2419.e4. [PMID: 28781054 DOI: 10.1016/j.cub.2017.06.056] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 05/18/2017] [Accepted: 06/20/2017] [Indexed: 10/19/2022]
Abstract
Spontaneous patterns of activity in the developing visual system may play an important role in shaping the brain for function. During the period 4-9 dpf (days post-fertilization), larval zebrafish learn to hunt prey, a behavior that is critically dependent on the optic tectum. However, how spontaneous activity develops in the tectum over this period and the effect of visual experience are unknown. Here we performed two-photon calcium imaging of GCaMP6s zebrafish larvae at all days from 4 to 9 dpf. Using recently developed graph theoretic techniques, we found significant changes in both single-cell and population activity characteristics over development. In particular, we identified days 5-6 as a critical moment in the reorganization of the underlying functional network. Altering visual experience early in development altered the statistics of tectal activity, and dark rearing also caused a long-lasting deficit in the ability to capture prey. Thus, tectal development is shaped by both intrinsic factors and visual experience.
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Affiliation(s)
- Lilach Avitan
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Zac Pujic
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jan Mölter
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Matthew Van De Poll
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Biao Sun
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Haotian Teng
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rumelo Amor
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ethan K Scott
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Geoffrey J Goodhill
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072, Australia.
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8
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Truszkowski TLS, Carrillo OA, Bleier J, Ramirez-Vizcarrondo CM, Felch DL, McQuillan M, Truszkowski CP, Khakhalin AS, Aizenman CD. A cellular mechanism for inverse effectiveness in multisensory integration. eLife 2017; 6:e25392. [PMID: 28315524 PMCID: PMC5375642 DOI: 10.7554/elife.25392] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/15/2017] [Indexed: 12/16/2022] Open
Abstract
To build a coherent view of the external world, an organism needs to integrate multiple types of sensory information from different sources, a process known as multisensory integration (MSI). Previously, we showed that the temporal dependence of MSI in the optic tectum of Xenopus laevis tadpoles is mediated by the network dynamics of the recruitment of local inhibition by sensory input (Felch et al., 2016). This was one of the first cellular-level mechanisms described for MSI. Here, we expand this cellular level view of MSI by focusing on the principle of inverse effectiveness, another central feature of MSI stating that the amount of multisensory enhancement observed inversely depends on the size of unisensory responses. We show that non-linear summation of crossmodal synaptic responses, mediated by NMDA-type glutamate receptor (NMDARs) activation, form the cellular basis for inverse effectiveness, both at the cellular and behavioral levels.
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Affiliation(s)
| | - Oscar A Carrillo
- Department of Neuroscience, Brown University, Providence, United States
| | - Julia Bleier
- Department of Neuroscience, Brown University, Providence, United States
| | | | - Daniel L Felch
- Department of Neuroscience, Brown University, Providence, United States
| | | | | | | | - Carlos D Aizenman
- Department of Neuroscience, Brown University, Providence, United States
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9
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Jang EV, Ramirez-Vizcarrondo C, Aizenman CD, Khakhalin AS. Emergence of Selectivity to Looming Stimuli in a Spiking Network Model of the Optic Tectum. Front Neural Circuits 2016; 10:95. [PMID: 27932957 PMCID: PMC5121234 DOI: 10.3389/fncir.2016.00095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 11/08/2016] [Indexed: 11/13/2022] Open
Abstract
The neural circuits in the optic tectum of Xenopus tadpoles are selectively responsive to looming visual stimuli that resemble objects approaching the animal at a collision trajectory. This selectivity is required for adaptive collision avoidance behavior in this species, but its underlying mechanisms are not known. In particular, it is still unclear how the balance between the recurrent spontaneous network activity and the newly arriving sensory flow is set in this structure, and to what degree this balance is important for collision detection. Also, despite the clear indication for the presence of strong recurrent excitation and spontaneous activity, the exact topology of recurrent feedback circuits in the tectum remains elusive. In this study we take advantage of recently published detailed cell-level data from tadpole tectum to build an informed computational model of it, and investigate whether dynamic activation in excitatory recurrent retinotopic networks may on its own underlie collision detection. We consider several possible recurrent connectivity configurations and compare their performance for collision detection under different levels of spontaneous neural activity. We show that even in the absence of inhibition, a retinotopic network of quickly inactivating spiking neurons is naturally selective for looming stimuli, but this selectivity is not robust to neuronal noise, and is sensitive to the balance between direct and recurrent inputs. We also describe how homeostatic modulation of intrinsic properties of individual tectal cells can change selectivity thresholds in this network, and qualitatively verify our predictions in a behavioral experiment in freely swimming tadpoles.
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Affiliation(s)
- Eric V Jang
- Department of Neuroscience, Brown University Providence, RI, USA
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10
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Pratt KG, Hiramoto M, Cline HT. An Evolutionarily Conserved Mechanism for Activity-Dependent Visual Circuit Development. Front Neural Circuits 2016; 10:79. [PMID: 27818623 PMCID: PMC5073143 DOI: 10.3389/fncir.2016.00079] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/26/2016] [Indexed: 12/01/2022] Open
Abstract
Neural circuit development is an activity-dependent process. This activity can be spontaneous, such as the retinal waves that course across the mammalian embryonic retina, or it can be sensory-driven, such as the activation of retinal ganglion cells (RGCs) by visual stimuli. Whichever the source, neural activity provides essential instruction to the developing circuit. Indeed, experimentally altering activity has been shown to impact circuit development and function in many different ways and in many different model systems. In this review, we contemplate the idea that retinal waves in amniotes, the animals that develop either in ovo or utero (namely reptiles, birds and mammals) could be an evolutionary adaptation to life on land, and that the anamniotes, animals whose development is entirely external (namely the aquatic amphibians and fish), do not display retinal waves, most likely because they simply don’t need them. We then review what is known about the function of both retinal waves and visual stimuli on their respective downstream targets, and predict that the experience-dependent development of the tadpole visual system is a blueprint of what will be found in future studies of the effects of spontaneous retinal waves on instructing development of retinorecipient targets such as the superior colliculus (SC) and the lateral geniculate nucleus.
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Affiliation(s)
- Kara G Pratt
- Program in Neuroscience, Department of Zoology and Physiology, University of Wyoming Laramie, WY, USA
| | - Masaki Hiramoto
- Department of Molecular and Cellular Neuroscience and The Dorris Neuroscience Center, The Scripps Research Institute La Jolla, CA, USA
| | - Hollis T Cline
- Department of Molecular and Cellular Neuroscience and The Dorris Neuroscience Center, The Scripps Research Institute La Jolla, CA, USA
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Gao J, Ruan H, Qi X, Tao Y, Guo X, Shen W. HDAC3 But not HDAC2 Mediates Visual Experience-Dependent Radial Glia Proliferation in the Developing Xenopus Tectum. Front Cell Neurosci 2016; 10:221. [PMID: 27729849 PMCID: PMC5037170 DOI: 10.3389/fncel.2016.00221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 09/09/2016] [Indexed: 01/12/2023] Open
Abstract
Radial glial cells (RGs) are one of the important progenitor cells that can differentiate into neurons or glia to form functional neural circuits in the developing central nervous system (CNS). Histone deacetylases (HDACs) has been associated with visual activity dependent changes in BrdU-positive progenitor cells in the developing brain. We previously have shown that HDAC1 is involved in the experience-dependent proliferation of RGs. However, it is less clear whether two other members of class I HDACs, HDAC2 and HDAC3, are involved in the regulation of radial glia proliferation. Here, we reported that HDAC2 and HDAC3 expression were developmentally regulated in tectal cells, especially in the ventricular layer of the BLBP-positive RGs. Pharmacological blockade using an inhibitor of class I HDACs, MS-275, decreased the number of BrdU-positive dividing progenitor cells. Specific knockdown of HDAC3 but not HDAC2 decreased the number of BrdU- and BLBP-labeled cells, suggesting that the proliferation of radial glia was selectively mediated by HDAC3. Visual deprivation induced selective augmentation of histone H4 acetylation at lysine 16 in BLBP-positive cells. Furthermore, the visual deprivation-induced increase in BrdU-positive cells was partially blocked by HDAC3 downregulation but not by HDAC2 knockdown at stage 49 tadpoles. These data revealed a specific role of HDAC3 in experience-dependent radial glia proliferation during the development of Xenopus tectum.
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Affiliation(s)
- Juanmei Gao
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, Zhejiang, China
| | - Hangze Ruan
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, Zhejiang, China
| | - Xianjie Qi
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, Zhejiang, China
| | - Yi Tao
- Department of Neurosurgery, Nanjing Medical University and Jiangsu Cancer Hospital Nanjing, Jiangsu, China
| | - Xia Guo
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, Zhejiang, China
| | - Wanhua Shen
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, Zhejiang, China
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12
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Fragile X mental retardation protein knockdown in the developing Xenopus tadpole optic tectum results in enhanced feedforward inhibition and behavioral deficits. Neural Dev 2016; 11:14. [PMID: 27503008 PMCID: PMC4977860 DOI: 10.1186/s13064-016-0069-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/03/2016] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Fragile X Syndrome is the leading monogenetic cause of autism and most common form of intellectual disability. Previous studies have implicated changes in dendritic spine architecture as the primary result of loss of Fragile X Mental Retardation Protein (FMRP), but recent work has shown that neural proliferation is decreased and cell death is increased with either loss of FMRP or overexpression of FMRP. The purpose of this study was to investigate the effects of loss of FMRP on behavior and cellular activity. METHODS We knocked down FMRP expression using morpholino oligos in the optic tectum of Xenopus laevis tadpoles and performed a series of behavioral and electrophysiological assays. We investigated visually guided collision avoidance, schooling, and seizure propensity. Using single cell electrophysiology, we assessed intrinsic excitability and synaptic connectivity of tectal neurons. RESULTS We found that FMRP knockdown results in decreased swimming speed, reduced schooling behavior and decreased seizure severity. In single cells, we found increased inhibition relative to excitation in response to sensory input. CONCLUSIONS Our results indicate that the electrophysiological development of single cells in the absence of FMRP is largely unaffected despite the large neural proliferation defect. The changes in behavior are consistent with an increase in inhibition, which could be due to either changes in cell number or altered inhibitory drive, and indicate that FMRP can play a significant role in neural development much earlier than previously thought.
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13
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Liu Z, Hamodi AS, Pratt KG. Early development and function of the Xenopus tadpole retinotectal circuit. Curr Opin Neurobiol 2016; 41:17-23. [PMID: 27475307 DOI: 10.1016/j.conb.2016.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/28/2016] [Accepted: 07/10/2016] [Indexed: 01/14/2023]
Abstract
The retinotectal circuit is the major component of the amphibian visual system. It is comprised of the retinal ganglion cells (RGCs) in the eye, which project their axons to the optic tectum and form synapses onto postsynaptic tectal neurons. The retinotectal circuit is relatively simple, and develops quickly: Xenopus tadpoles begin displaying retinotectal-dependent visual avoidance behaviors by approximately 7-8 days post-fertilization, early larval stage. In this review we first provide a summary of the dynamic development of the retinotectal circuit, including the microcircuitry formed by local tectal-tectal connections within the tectum. Second, we discuss the basic visual avoidance behavior generated specifically by this circuit, and how this behavior is being used as an assay to test visual system function.
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Affiliation(s)
- Zhenyu Liu
- Department of Zoology and Physiology and Program in Neuroscience, University of Wyoming, Laramie, WY 82071, United States
| | - Ali S Hamodi
- Department of Zoology and Physiology and Program in Neuroscience, University of Wyoming, Laramie, WY 82071, United States
| | - Kara G Pratt
- Department of Zoology and Physiology and Program in Neuroscience, University of Wyoming, Laramie, WY 82071, United States.
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14
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He HY, Shen W, Hiramoto M, Cline HT. Experience-Dependent Bimodal Plasticity of Inhibitory Neurons in Early Development. Neuron 2016; 90:1203-1214. [PMID: 27238867 DOI: 10.1016/j.neuron.2016.04.044] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 03/11/2016] [Accepted: 04/14/2016] [Indexed: 02/09/2023]
Abstract
Inhibitory neurons are heterogeneous in the mature brain. It is unclear when and how inhibitory neurons express distinct structural and functional profiles. Using in vivo time-lapse imaging of tectal neuron structure and visually evoked Ca(2+) responses in tadpoles, we found that inhibitory neurons cluster into two groups with opposite valence of plasticity after 4 hr of dark and visual stimulation. Half decreased dendritic arbor size and Ca(2+) responses after dark and increased them after visual stimulation, matching plasticity in excitatory neurons. Half increased dendrite arbor size and Ca(2+) responses following dark and decreased them after stimulation. At the circuit level, visually evoked excitatory and inhibitory synaptic inputs were potentiated by visual experience and E/I remained constant. Our results indicate that developing inhibitory neurons fall into distinct functional groups with opposite experience-dependent plasticity and as such, are well positioned to foster experience-dependent synaptic plasticity and maintain circuit stability during labile periods of circuit development.
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Affiliation(s)
- Hai-Yan He
- The Dorris Neuroscience Center, Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Wanhua Shen
- Key Lab of Organ Development and Regeneration of Zhejiang Province, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Masaki Hiramoto
- The Dorris Neuroscience Center, Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Hollis T Cline
- The Dorris Neuroscience Center, Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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15
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Ciarleglio CM, Khakhalin AS, Wang AF, Constantino AC, Yip SP, Aizenman CD. Multivariate analysis of electrophysiological diversity of Xenopus visual neurons during development and plasticity. eLife 2015; 4. [PMID: 26568314 PMCID: PMC4728129 DOI: 10.7554/elife.11351] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/12/2015] [Indexed: 12/26/2022] Open
Abstract
Biophysical properties of neurons become increasingly diverse over development, but mechanisms underlying and constraining this diversity are not fully understood. Here we investigate electrophysiological characteristics of Xenopus tadpole midbrain neurons across development and during homeostatic plasticity induced by patterned visual stimulation. We show that in development tectal neuron properties not only change on average, but also become increasingly diverse. After sensory stimulation, both electrophysiological diversity and functional differentiation of cells are reduced. At the same time, the amount of cross-correlations between cell properties increase after patterned stimulation as a result of homeostatic plasticity. We show that tectal neurons with similar spiking profiles often have strikingly different electrophysiological properties, and demonstrate that changes in intrinsic excitability during development and in response to sensory stimulation are mediated by different underlying mechanisms. Overall, this analysis and the accompanying dataset provide a unique framework for further studies of network maturation in Xenopus tadpoles.
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Affiliation(s)
- Christopher M Ciarleglio
- Biology Program, Brown University, Annandale-on-Hudson, United States.,Department of Neuroscience, Brown University, Providence, United States
| | - Arseny S Khakhalin
- Biology Program, Bard College, Annandale-on-Hudson, United States.,Department of Neuroscience, Brown University, Providence, United States
| | - Angelia F Wang
- Biology Program, Bard College, Annandale-on-Hudson, United States.,Department of Neuroscience, Brown University, Providence, United States
| | - Alexander C Constantino
- Biology Program, Bard College, Annandale-on-Hudson, United States.,Department of Neuroscience, Brown University, Providence, United States
| | - Sarah P Yip
- Biology Program, Bard College, Annandale-on-Hudson, United States.,Department of Neuroscience, Brown University, Providence, United States
| | - Carlos D Aizenman
- Biology Program, Bard College, Annandale-on-Hudson, United States.,Department of Neuroscience, Brown University, Providence, United States
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16
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Khakhalin AS, Koren D, Gu J, Xu H, Aizenman CD. Excitation and inhibition in recurrent networks mediate collision avoidance in Xenopus tadpoles. Eur J Neurosci 2014; 40:2948-62. [PMID: 24995793 DOI: 10.1111/ejn.12664] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/23/2014] [Accepted: 05/28/2014] [Indexed: 01/24/2023]
Abstract
Information processing in the vertebrate brain is thought to be mediated through distributed neural networks, but it is still unclear how sensory stimuli are encoded and detected by these networks, and what role synaptic inhibition plays in this process. Here we used a collision avoidance behavior in Xenopus tadpoles as a model for stimulus discrimination and recognition. We showed that the visual system of the tadpole is selective for behaviorally relevant looming stimuli, and that the detection of these stimuli first occurs in the optic tectum. By comparing visually guided behavior, optic nerve recordings, excitatory and inhibitory synaptic currents, and the spike output of tectal neurons, we showed that collision detection in the tadpole relies on the emergent properties of distributed recurrent networks within the tectum. We found that synaptic inhibition was temporally correlated with excitation, and did not actively sculpt stimulus selectivity, but rather it regulated the amount of integration between direct inputs from the retina and recurrent inputs from the tectum. Both pharmacological suppression and enhancement of synaptic inhibition disrupted emergent selectivity for looming stimuli. Taken together these findings suggested that, by regulating the amount of network activity, inhibition plays a critical role in maintaining selective sensitivity to behaviorally-relevant visual stimuli.
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Affiliation(s)
- Arseny S Khakhalin
- Department of Neuroscience, Brown University, Box G-LN, Providence, RI, 02912, USA
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17
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Global hyper-synchronous spontaneous activity in the developing optic tectum. Sci Rep 2013; 3:1552. [PMID: 23531884 PMCID: PMC3609019 DOI: 10.1038/srep01552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 03/08/2013] [Indexed: 01/19/2023] Open
Abstract
Studies of patterned spontaneous activity can elucidate how the organization of neural circuits emerges. Using in vivo two-photon Ca2+ imaging, we studied spatio-temporal patterns of spontaneous activity in the optic tectum of Xenopus tadpoles. We found rhythmic patterns of global synchronous spontaneous activity between neurons, which depends on visual experience and developmental stage. By contrast, synchronous spontaneous activity between non-neuronal cells is mediated more locally. To understand the source of the neuronal spontaneous activity, input to the tectum was systematically removed. Whereas removing input from the visual or mechanosensory system alone had little effect on patterned spontaneous activity, removing input from both systems drastically altered it. These results suggest that either input is sufficient to maintain the intrinsically generated spontaneous activity and that patterned spontaneous activity results from input from multisensory systems. Thus, the amphibian midbrain differs from the mammalian visual system, whose spontaneous activity is controlled by retinal waves.
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18
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Pratt KG, Khakhalin AS. Modeling human neurodevelopmental disorders in the Xenopus tadpole: from mechanisms to therapeutic targets. Dis Model Mech 2013; 6:1057-65. [PMID: 23929939 PMCID: PMC3759326 DOI: 10.1242/dmm.012138] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The Xenopus tadpole model offers many advantages for studying the molecular, cellular and network mechanisms underlying neurodevelopmental disorders. Essentially every stage of normal neural circuit development, from axon outgrowth and guidance to activity-dependent homeostasis and refinement, has been studied in the frog tadpole, making it an ideal model to determine what happens when any of these stages are compromised. Recently, the tadpole model has been used to explore the mechanisms of epilepsy and autism, and there is mounting evidence to suggest that diseases of the nervous system involve deficits in the most fundamental aspects of nervous system function and development. In this Review, we provide an update on how tadpole models are being used to study three distinct types of neurodevelopmental disorders: diseases caused by exposure to environmental toxicants, epilepsy and seizure disorders, and autism.
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Affiliation(s)
- Kara G. Pratt
- University of Wyoming, 1000 E University Avenue, Laramie, WY 82071, USA
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19
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A competition-based mechanism mediates developmental refinement of tectal neuron receptive fields. J Neurosci 2013; 32:16872-9. [PMID: 23175839 DOI: 10.1523/jneurosci.2372-12.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Neural activity plays an important role in development and maturation of visual circuits in the brain. Activity can be instructive in refining visual projections by directly mediating formation and elimination of specific synaptic contacts through competition-based mechanisms. Alternatively, activity could be permissive-regulating production of factors that create a favorable environment for circuit refinement. Here we used the Xenopus laevis tadpole visual system to test whether activity is instructive or permissive for shaping development of the retinotectal circuit. In vivo spike output was dampened in a small subgroup of tectal neurons, starting from developmental stages 44-46, by overexpressing Shaker-like Xenopus Kv1.1 potassium channels using electroporation. Tadpoles were then reared until stage 49, a time period when significant refinement of the retinotectal map occurs. Kv1.1-expressing neurons had significantly decreased spike output in response to both current injection and visual stimuli compared to untransfected controls, with spiking occurring during a more limited time interval. We found that Kv1.1-expressing neurons had larger visual receptive fields, decreased receptive field sharpness, and more persistent recurrent excitation than control neurons, all of which are characteristics of immature neurons. Transfected cells, however, had normal spontaneous excitatory synaptic currents and dendritic arbors. These results suggest that spike output of a tectal neuron plays an important instructive role in development of its receptive field properties and refinement of local circuits. However, other activity-dependent processes, such as synaptogenesis and dendritic growth, remain unaffected due to the permissive environment created by otherwise normal network activity.
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20
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Spawn A, Aizenman CD. Abnormal visual processing and increased seizure susceptibility result from developmental exposure to the biocide methylisothiazolinone. Neuroscience 2012; 205:194-204. [PMID: 22245758 DOI: 10.1016/j.neuroscience.2011.12.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/23/2011] [Accepted: 12/28/2011] [Indexed: 12/21/2022]
Abstract
Methylisothiazolinone (MIT) is a commonly used biocide known to be neurotoxic in vitro. Brief exposure of cortical neurons in culture to MIT results in increased neurodegeneration, whereas chronic exposure of developing neurons in culture to low concentrations of MIT has been shown to interfere with normal neurite outgrowth. However, the effects of chronic MIT exposure on the developing nervous system have not been tested in vivo. Here we expose Xenopus laevis tadpoles to sub-lethal concentrations of MIT during a critical period in neural development. We find that MIT exposure results in deficits in visually mediated avoidance behavior and increased susceptibility to seizures, as well electrophysiological abnormalities in optic tectal function, without any effects on overall morphology, gross anatomy of the visual projections, overall visual function, and swimming ability. These effects indicate that chronic exposure to low levels of MIT results in neural circuit-level deficits that result in abnormal neurological function without causing increased mortality or even gross anatomical defects. Our findings, combined with the fact that the long-term neurological impacts of environmental exposure to MIT have not been determined, suggest a need for a closer evaluation of the safety of MIT in commercial and industrial products.
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Affiliation(s)
- A Spawn
- Department of Neuroscience, Box G-LN, Brown University, Providence, RI 02912, USA
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