1
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Napoli AJ, Laderwager S, Zoodsma JD, Biju B, Mucollari O, Schubel SK, Aprea C, Sayed A, Morgan K, Napoli A, Flanagan S, Wollmuth LP, Sirotkin HI. Developmental loss of NMDA receptors results in supernumerary forebrain neurons through delayed maturation of transit-amplifying neuroblasts. Sci Rep 2024; 14:3395. [PMID: 38336823 PMCID: PMC10858180 DOI: 10.1038/s41598-024-53910-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 02/06/2024] [Indexed: 02/12/2024] Open
Abstract
Developmental neurogenesis is a tightly regulated spatiotemporal process with its dysregulation implicated in neurodevelopmental disorders. NMDA receptors are glutamate-gated ion channels that are widely expressed in the early nervous system, yet their contribution to neurogenesis is poorly understood. Notably, a variety of mutations in genes encoding NMDA receptor subunits are associated with neurodevelopmental disorders. To rigorously define the role of NMDA receptors in developmental neurogenesis, we used a mutant zebrafish line (grin1-/-) that lacks all NMDA receptors yet survives to 10 days post-fertilization, offering the opportunity to study post-embryonic neurodevelopment in the absence of NMDA receptors. Focusing on the forebrain, we find that these fish have a progressive supernumerary neuron phenotype confined to the telencephalon at the end of embryonic neurogenesis, but which extends to all forebrain regions during postembryonic neurogenesis. This enhanced neuron population does not arise directly from increased numbers or mitotic activity of radial glia cells, the principal neural stem cells. Rather, it stems from a lack of timely maturation of transit-amplifying neuroblasts into post-mitotic neurons, as indicated by a decrease in expression of the ontogenetically-expressed chloride transporter, KCC2. Pharmacological blockade with MK-801 recapitulates the grin1-/- supernumerary neuron phenotype, indicating a requirement for ionotropic signaling. Thus, NMDA receptors are required for suppression of indirect, transit amplifying cell-driven neurogenesis by promoting maturational termination of mitosis. Loss of suppression results in neuronal overpopulation that can fundamentally change brain circuitry and may be a key factor in pathogenesis of neurodevelopmental disorders caused by NMDA receptor dysfunction.
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Affiliation(s)
- Amalia J Napoli
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Stephanie Laderwager
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
- Graduate Program in Neuroscience, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Josiah D Zoodsma
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Bismi Biju
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Olgerta Mucollari
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Sarah K Schubel
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Christieann Aprea
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Aaliya Sayed
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Kiele Morgan
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Annelysia Napoli
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Stephanie Flanagan
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Lonnie P Wollmuth
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794-5215, USA
- Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Howard I Sirotkin
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA.
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2
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Udoh UG, Bruno JR, Osborn PO, Pratt KG. Serotonin Strengthens a Developing Glutamatergic Synapse through a PI3K-Dependent Mechanism. J Neurosci 2024; 44:e1260232023. [PMID: 38169457 PMCID: PMC10860612 DOI: 10.1523/jneurosci.1260-23.2023] [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: 07/07/2023] [Revised: 11/22/2023] [Accepted: 11/29/2023] [Indexed: 01/05/2024] Open
Abstract
It is well established that, during neural circuit development, glutamatergic synapses become strengthened via NMDA receptor (NMDAR)-dependent upregulation of AMPA receptor (AMPAR)-mediated currents. In addition, however, it is known that the neuromodulator serotonin is present throughout most regions of the vertebrate brain while synapses are forming and being shaped by activity-dependent processes. This suggests that serotonin may modulate or contribute to these processes. Here, we investigate the role of serotonin in the developing retinotectal projection of the Xenopus tadpole. We altered endogenous serotonin transmission in stage 48/49 (∼10-21 days postfertilization) Xenopus tadpoles and then carried out a set of whole-cell electrophysiological recordings from tectal neurons to assess retinotectal synaptic transmission. Because tadpole sex is indeterminate at these early stages of development, experimental groups were composed of randomly chosen tadpoles. We found that pharmacologically enhancing and reducing serotonin transmission for 24 h up- and downregulates, respectively, AMPAR-mediated currents at individual retinotectal synapses. Inhibiting 5-HT2 receptors also significantly weakened AMPAR-mediated currents and abolished the synapse strengthening effect seen with enhanced serotonin transmission, indicating a 5-HT2 receptor-dependent effect. We also determine that the serotonin-dependent upregulation of synaptic AMPAR currents was mediated via an NMDAR-independent, PI3K-dependent mechanism. Altogether, these findings indicate that serotonin regulates AMPAR currents at developing synapses independent of NMDA transmission, which may explain its role as an enabler of activity-dependent plasticity.
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Affiliation(s)
- Uwemedimo G Udoh
- Department of Zoology and Physiology, University of Wyoming, Laramie 82071, Wyoming
- Program in Neuroscience, University of Wyoming, Laramie 82071, Wyoming
| | - John R Bruno
- Department of Zoology and Physiology, University of Wyoming, Laramie 82071, Wyoming
| | - Paige O Osborn
- Department of Zoology and Physiology, University of Wyoming, Laramie 82071, Wyoming
| | - Kara G Pratt
- Department of Zoology and Physiology, University of Wyoming, Laramie 82071, Wyoming
- Program in Neuroscience, University of Wyoming, Laramie 82071, Wyoming
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3
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Foubert D, Cookson F, Ruthazer ES. Capturing a rising star: the emerging role of astrocytes in neural circuit wiring and plasticity-lessons from the visual system. NEUROPHOTONICS 2023; 10:044408. [PMID: 37766925 PMCID: PMC10520262 DOI: 10.1117/1.nph.10.4.044408] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/29/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023]
Abstract
The increasingly widespread use of calcium imaging to explore the nature of neuronal activity and circuits has unexpectedly revealed the ubiquitous presence and significance of astrocytic activity. Here, we present a brief review of visual system development, placing it in the context of recently identified roles of astrocytes in the modulation of neuronal responses and circuit plasticity, through their responses to sensory stimuli and the release of gliotransmitters.
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Affiliation(s)
- David Foubert
- Montreal Neurological Institute-Hospital, Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Finnley Cookson
- Montreal Neurological Institute-Hospital, Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Edward S. Ruthazer
- Montreal Neurological Institute-Hospital, Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
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4
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Sherman S, Arnold-Ammer I, Schneider MW, Kawakami K, Baier H. Retina-derived signals control pace of neurogenesis in visual brain areas but not circuit assembly. Nat Commun 2023; 14:6020. [PMID: 37758715 PMCID: PMC10533834 DOI: 10.1038/s41467-023-40749-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 08/09/2023] [Indexed: 09/29/2023] Open
Abstract
Brain development is orchestrated by both innate and experience-dependent mechanisms, but their relative contributions are difficult to disentangle. Here we asked if and how central visual areas are altered in a vertebrate brain depleted of any and all signals from retinal ganglion cells throughout development. We transcriptionally profiled neurons in pretectum, thalamus and other retinorecipient areas of larval zebrafish and searched for changes in lakritz mutants that lack all retinal connections. Although individual genes are dysregulated, the complete set of 77 neuronal types develops in apparently normal proportions, at normal locations, and along normal differentiation trajectories. Strikingly, the cell-cycle exits of proliferating progenitors in these areas are delayed, and a greater fraction of early postmitotic precursors remain uncommitted or are diverted to a pre-glial fate. Optogenetic stimulation targeting groups of neurons normally involved in processing visual information evokes behaviors indistinguishable from wildtype. In conclusion, we show that signals emitted by retinal axons influence the pace of neurogenesis in visual brain areas, but do not detectably affect the specification or wiring of downstream neurons.
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Affiliation(s)
- Shachar Sherman
- Max Planck Institute for Biological Intelligence, Department Genes - Circuits - Behavior, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Irene Arnold-Ammer
- Max Planck Institute for Biological Intelligence, Department Genes - Circuits - Behavior, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Martin W Schneider
- Max Planck Institute for Biological Intelligence, Department Genes - Circuits - Behavior, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, and Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, Shizuoka, 411-8540, Japan
| | - Herwig Baier
- Max Planck Institute for Biological Intelligence, Department Genes - Circuits - Behavior, Am Klopferspitz 18, 82152, Martinsried, Germany.
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5
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Napoli AJ, Laderwager S, Zoodsma JD, Biju B, Mucollari O, Schubel SK, Aprea C, Sayed A, Morgan K, Napoli A, Flanagan S, Wollmuth LP, Sirotkin HI. Loss of NMDA receptor function during development results in decreased KCC2 expression and increased neurons in the zebrafish forebrain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.25.554812. [PMID: 37786708 PMCID: PMC10541604 DOI: 10.1101/2023.08.25.554812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Developmental neurogenesis is a tightly regulated spatiotemporal process with its dysregulation implicated in neurodevelopmental disorders. NMDA receptors are glutamate-gated ion channels that are widely expressed in the early nervous system, yet their contribution to neurogenesis is poorly understood. Notably, a variety of mutations in genes encoding NMDA receptor subunits are associated with neurodevelopmental disorders. To rigorously define the role of NMDA receptors in developmental neurogenesis, we used a mutant zebrafish line ( grin1 -/- ) that lacks all NMDA receptors yet survives to 10 days post-fertilization, offering the opportunity to study post-embryonic neurodevelopment in the absence of NMDA receptors. Focusing on the forebrain, we find that these fish have a progressive supernumerary neuron phenotype confined to the telencephalon at the end of embryonic neurogenesis, but which extends to all forebrain regions during postembryonic neurogenesis. This enhanced neuron population does not arise directly from increased numbers or mitotic activity of radial glia cells, the principal neural stem cells. Rather, it stems from a lack of timely maturation of transit-amplifying neuroblasts into post-mitotic neurons, as indicated by a decrease in expression of the ontogenetically-expressed chloride transporter, KCC2. Pharmacological blockade with MK-801 recapitulates the grin1 -/- supernumerary neuron phenotype, indicating a requirement for ionotropic signaling. Thus, NMDA receptors are required for suppression of indirect, transit amplifying cell-driven neurogenesis by promoting maturational termination of mitosis. Loss of suppression results in neuronal overpopulation that can fundamentally change brain circuitry and may be a key factor in pathogenesis of neurodevelopmental disorders caused by NMDA receptor dysfunction.
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6
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Suárez R, Bluett T, McCullough MH, Avitan L, Black DA, Paolino A, Fenlon LR, Goodhill GJ, Richards LJ. Cortical activity emerges in region-specific patterns during early brain development. Proc Natl Acad Sci U S A 2023; 120:e2208654120. [PMID: 37216522 PMCID: PMC10235933 DOI: 10.1073/pnas.2208654120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 04/17/2023] [Indexed: 05/24/2023] Open
Abstract
The development of precise neural circuits in the brain requires spontaneous patterns of neural activity prior to functional maturation. In the rodent cerebral cortex, patchwork and wave patterns of activity develop in somatosensory and visual regions, respectively, and are present at birth. However, whether such activity patterns occur in noneutherian mammals, as well as when and how they arise during development, remain open questions relevant for understanding brain formation in health and disease. Since the onset of patterned cortical activity is challenging to study prenatally in eutherians, here we offer an approach in a minimally invasive manner using marsupial dunnarts, whose cortex forms postnatally. We discovered similar patchwork and travelling waves in the dunnart somatosensory and visual cortices at stage 27 (equivalent to newborn mice) and examined earlier stages of development to determine the onset of these patterns and how they first emerge. We observed that these patterns of activity emerge in a region-specific and sequential manner, becoming evident as early as stage 24 in somatosensory and stage 25 in visual cortices (equivalent to embryonic day 16 and 17, respectively, in mice), as cortical layers establish and thalamic axons innervate the cortex. In addition to sculpting synaptic connections of existing circuits, evolutionarily conserved patterns of neural activity could therefore help regulate other early events in cortical development.
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Affiliation(s)
- Rodrigo Suárez
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
- The University of Queensland, School of Biomedical Sciences, BrisbaneQLD4072, Australia
| | - Tobias Bluett
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
| | - Michael H. McCullough
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
| | - Lilach Avitan
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
| | - Dylan A. Black
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
- The University of Queensland, School of Biomedical Sciences, BrisbaneQLD4072, Australia
| | - Annalisa Paolino
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
- The University of Queensland, School of Biomedical Sciences, BrisbaneQLD4072, Australia
| | - Laura R. Fenlon
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
- The University of Queensland, School of Biomedical Sciences, BrisbaneQLD4072, Australia
| | - Geoffrey J. Goodhill
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
- The University of Queensland, School of Mathematics and Physics, BrisbaneQLD4072, Australia
| | - Linda J. Richards
- The University of Queensland, Queensland Brain Institute, BrisbaneQLD4072, Australia
- The University of Queensland, School of Biomedical Sciences, BrisbaneQLD4072, Australia
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7
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Suárez R, Bluett T, McCullough MH, Avitan L, Black DA, Paolino A, Fenlon LR, Goodhill GJ, Richards LJ. Cortical activity emerges in region-specific patterns during early brain development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.18.529078. [PMID: 36824827 PMCID: PMC9949140 DOI: 10.1101/2023.02.18.529078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
The development of precise neural circuits in the brain requires spontaneous patterns of neural activity prior to functional maturation. In the rodent cerebral cortex patchwork and wave patterns of activity develop in somatosensory and visual regions, respectively, and are present at birth. However, whether such activity patterns occur in non-eutherian mammals, as well as when and how they arise during development remain open questions relevant to understand brain formation in health and disease. Since the onset of patterned cortical activity is challenging to study prenatally in eutherians, here we offer a new approach in a minimally invasive manner using marsupial dunnarts, whose cortex forms postnatally. We discovered similar patchwork and travelling waves in the dunnart somatosensory and visual cortices at stage 27 (equivalent to newborn mice), and examined progressively earlier stages of development to determine their onset and how they first emerge. We observed that these patterns of activity emerge in a region-specific and sequential manner, becoming evident as early as stage 24 in somatosensory and stage 25 in visual cortices (equivalent to embryonic day 16 and 17, respectively, in mice), as cortical layers establish and thalamic axons innervate the cortex. In addition to sculpting synaptic connections of existing circuits, evolutionarily conserved patterns of neural activity could therefore help regulate early events in cortical development. Significance Statement Region-specific patterns of neural activity are present at birth in rodents and are thought to refine synaptic connections during critical periods of cerebral cortex development. Marsupials are born much more immature than rodents, allowing the investigation of how these patterns arise in vivo. We discovered that cortical activity patterns are remarkably similar in marsupial dunnarts and rodents, and that they emerge very early, before cortical neurogenesis is complete. Moreover, they arise from the outset in different patterns specific to somatosensory and visual areas (i.e., patchworks and waves) indicating they may also play evolutionarily conserved roles in cortical regionalization during development.
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Affiliation(s)
- Rodrigo Suárez
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
- The University of Queensland, School of Biomedical Sciences; Brisbane, Australia
| | - Tobias Bluett
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
| | | | - Lilach Avitan
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
| | - Dylan A. Black
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
- The University of Queensland, School of Biomedical Sciences; Brisbane, Australia
| | - Annalisa Paolino
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
- The University of Queensland, School of Biomedical Sciences; Brisbane, Australia
| | - Laura R. Fenlon
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
- The University of Queensland, School of Biomedical Sciences; Brisbane, Australia
| | - Geoffrey J. Goodhill
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
- The University of Queensland, School of Mathematics and Physics; Brisbane, Australia
| | - Linda J. Richards
- The University of Queensland, Queensland Brain Institute; Brisbane, Australia
- The University of Queensland, School of Biomedical Sciences; Brisbane, Australia
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8
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Kutsarova E, Schohl A, Munz M, Wang A, Zhang YY, Bilash OM, Ruthazer ES. BDNF signaling in correlation-dependent structural plasticity in the developing visual system. PLoS Biol 2023; 21:e3002070. [PMID: 37011100 PMCID: PMC10101647 DOI: 10.1371/journal.pbio.3002070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 04/13/2023] [Accepted: 03/08/2023] [Indexed: 04/05/2023] Open
Abstract
During development, patterned neural activity instructs topographic map refinement. Axons with similar patterns of neural activity converge onto target neurons and stabilize their synapses with these postsynaptic partners, restricting exploratory branch elaboration (Hebbian structural plasticity). On the other hand, non-correlated firing in inputs leads to synapse weakening and increased exploratory growth of axons (Stentian structural plasticity). We used visual stimulation to control the correlation structure of neural activity in a few ipsilaterally projecting (ipsi) retinal ganglion cell (RGC) axons with respect to the majority contralateral eye inputs in the optic tectum of albino Xenopus laevis tadpoles. Multiphoton live imaging of ipsi axons, combined with specific targeted disruptions of brain-derived neurotrophic factor (BDNF) signaling, revealed that both presynaptic p75NTR and TrkB are required for Stentian axonal branch addition, whereas presumptive postsynaptic BDNF signaling is necessary for Hebbian axon stabilization. Additionally, we found that BDNF signaling mediates local suppression of branch elimination in response to correlated firing of inputs. Daily in vivo imaging of contralateral RGC axons demonstrated that p75NTR knockdown reduces axon branch elongation and arbor spanning field volume.
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Affiliation(s)
- Elena Kutsarova
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
- Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Anne Schohl
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
| | - Martin Munz
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Alex Wang
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
- Interdepartmental Neuroscience, Yale University, New Haven, Connecticut, United States of America
| | - Yuan Yuan Zhang
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
- Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Olesia M Bilash
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
- NYU Neuroscience Institute, New York University, New York, New York, United States of America
| | - Edward S Ruthazer
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
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9
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de Montigny J, Sernagor E, Bauer R. Retinal self-organization: a model of retinal ganglion cells and starburst amacrine cells mosaic formation. Open Biol 2023; 13:220217. [PMID: 37015288 PMCID: PMC10072945 DOI: 10.1098/rsob.220217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023] Open
Abstract
Individual retinal cell types exhibit semi-regular spatial patterns called retinal mosaics. Retinal ganglion cells (RGCs) and starburst amacrine cells (SACs) are known to exhibit such layouts. Mechanisms responsible for the formation of mosaics are not well understood but follow three main principles: (i) homotypic cells prevent nearby cells from adopting the same type, (ii) cell tangential migration and (iii) cell death. Alongside experiments in mouse, we use BioDynaMo, an agent-based simulation framework, to build a detailed and mechanistic model of mosaic formation. We investigate the implications of the three theories for RGC's mosaic formation. We report that the cell migration mechanism yields the most regular mosaics. In addition, we propose that low-density RGC type mosaics exhibit on average low regularities, and thus we question the relevance of regular spacing as a criterion for a group of RGCs to form a RGC type. We investigate SAC mosaics formation and interactions between the ganglion cell layer (GCL) and inner nuclear layer (INL) populations. We propose that homotypic interactions between the GCL and INL populations during mosaics creation are required to reproduce the observed SAC mosaics' characteristics. This suggests that the GCL and INL populations of SACs might not be independent during retinal development.
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Affiliation(s)
- Jean de Montigny
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Evelyne Sernagor
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Roman Bauer
- Department of Computer Science, University of Surrey, Guildford GU2 7XH, UK
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10
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Li VJ, Chorghay Z, Ruthazer ES. A Guide for the Multiplexed: The Development of Visual Feature Maps in the Brain. Neuroscience 2023; 508:62-75. [PMID: 35952996 DOI: 10.1016/j.neuroscience.2022.07.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 07/21/2022] [Accepted: 07/27/2022] [Indexed: 01/17/2023]
Abstract
Neural maps are found ubiquitously in the brain, where they encode a wide range of behaviourally relevant features into neural space. Developmental studies have shown that animals devote a great deal of resources to establish consistently patterned organization in neural circuits throughout the nervous system, but what purposes maps serve beneath their often intricate appearance and composition is a topic of active debate and exploration. In this article, we review the general mechanisms of map formation, with a focus on the visual system, and then survey notable organizational properties of neural maps: the multiplexing of feature representations through a nested architecture, the interspersing of fine-scale heterogeneity within a globally smooth organization, and the complex integration at the microcircuit level that enables a high dimensionality of information encoding. Finally, we discuss the roles of maps in cortical functions, including input segregation, feature extraction and routing of circuit outputs for higher order processing, as well as the evolutionary basis for the properties we observe in neural maps.
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Affiliation(s)
- Vanessa J Li
- Montreal Neurological Institute-Hospital, McGill University, 3801 University St. Montreal, Quebec H3A 2B4, Canada
| | - Zahraa Chorghay
- Montreal Neurological Institute-Hospital, McGill University, 3801 University St. Montreal, Quebec H3A 2B4, Canada
| | - Edward S Ruthazer
- Montreal Neurological Institute-Hospital, McGill University, 3801 University St. Montreal, Quebec H3A 2B4, Canada
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11
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Cline HT, Lau M, Hiramoto M. Activity-dependent Organization of Topographic Neural Circuits. Neuroscience 2023; 508:3-18. [PMID: 36470479 PMCID: PMC9839526 DOI: 10.1016/j.neuroscience.2022.11.032] [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: 03/24/2022] [Revised: 11/25/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
Sensory information in the brain is organized into spatial representations, including retinotopic, somatotopic, and tonotopic maps, as well as ocular dominance columns. The spatial representation of sensory inputs is thought to be a fundamental organizational principle that is important for information processing. Topographic maps are plastic throughout an animal's life, reflecting changes in development and aging of brain circuitry, changes in the periphery and sensory input, and changes in circuitry, for instance in response to experience and learning. Here, we review mechanisms underlying the role of activity in the development, stability and plasticity of topographic maps, focusing on recent work suggesting that the spatial information in the visual field, and the resulting spatiotemporal patterns of activity, provide instructive cues that organize visual projections.
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Affiliation(s)
- Hollis T Cline
- Department of Neuroscience and the Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, USA.
| | - Melissa Lau
- Department of Neuroscience and the Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, USA
| | - Masaki Hiramoto
- Department of Neuroscience and the Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, USA
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12
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Gao J, Luo Y, Lu Y, Wu X, Chen P, Zhang X, Han L, Qiu M, Shen W. Epigenetic regulation of GABAergic differentiation in the developing brain. Front Cell Neurosci 2022; 16:988732. [PMID: 36212693 PMCID: PMC9539098 DOI: 10.3389/fncel.2022.988732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/18/2022] [Indexed: 11/13/2022] Open
Abstract
In the vertebrate brain, GABAergic cell development and neurotransmission are important for the establishment of neural circuits. Various intrinsic and extrinsic factors have been identified to affect GABAergic neurogenesis. However, little is known about the epigenetic control of GABAergic differentiation in the developing brain. Here, we report that the number of GABAergic neurons dynamically changes during the early tectal development in the Xenopus brain. The percentage of GABAergic neurons is relatively unchanged during the early stages from stage 40 to 46 but significantly decreased from stage 46 to 48 tadpoles. Interestingly, the histone acetylation of H3K9 is developmentally decreased from stage 42 to 48 (about 3.5 days). Chronic application of valproate acid (VPA), a broad-spectrum histone deacetylase (HDAC) inhibitor, at stage 46 for 48 h increases the acetylation of H3K9 and the number of GABAergic cells in the optic tectum. VPA treatment also reduces apoptotic cells. Electrophysiological recordings show that a VPA induces an increase in the frequency of mIPSCs and no changes in the amplitude. Behavioral studies reveal that VPA decreases swimming activity and visually guided avoidance behavior. These findings extend our understanding of histone modification in the GABAergic differentiation and neurotransmission during early brain development.
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Affiliation(s)
- Juanmei Gao
- College of Life Sciences, Zhejiang University, Hangzhou, China
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Yuhao Luo
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Yufang Lu
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xiaohua Wu
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Peiyao Chen
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xinyu Zhang
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Lu Han
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Mengsheng Qiu
- College of Life Sciences, Zhejiang University, Hangzhou, China
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
- *Correspondence: Mengsheng Qiu,
| | - Wanhua Shen
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
- Wanhua Shen,
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13
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Sedigh-Sarvestani M, Fitzpatrick D. What and Where: Location-Dependent Feature Sensitivity as a Canonical Organizing Principle of the Visual System. Front Neural Circuits 2022; 16:834876. [PMID: 35498372 PMCID: PMC9039279 DOI: 10.3389/fncir.2022.834876] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 03/01/2022] [Indexed: 11/13/2022] Open
Abstract
Traditionally, functional representations in early visual areas are conceived as retinotopic maps preserving ego-centric spatial location information while ensuring that other stimulus features are uniformly represented for all locations in space. Recent results challenge this framework of relatively independent encoding of location and features in the early visual system, emphasizing location-dependent feature sensitivities that reflect specialization of cortical circuits for different locations in visual space. Here we review the evidence for such location-specific encoding including: (1) systematic variation of functional properties within conventional retinotopic maps in the cortex; (2) novel periodic retinotopic transforms that dramatically illustrate the tight linkage of feature sensitivity, spatial location, and cortical circuitry; and (3) retinotopic biases in cortical areas, and groups of areas, that have been defined by their functional specializations. We propose that location-dependent feature sensitivity is a fundamental organizing principle of the visual system that achieves efficient representation of positional regularities in visual experience, and reflects the evolutionary selection of sensory and motor circuits to optimally represent behaviorally relevant information. Future studies are necessary to discover mechanisms underlying joint encoding of location and functional information, how this relates to behavior, emerges during development, and varies across species.
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14
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Topographic map formation and the effects of NMDA receptor blockade in the developing visual system. Proc Natl Acad Sci U S A 2022; 119:2107899119. [PMID: 35193956 PMCID: PMC8872792 DOI: 10.1073/pnas.2107899119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2022] [Indexed: 11/18/2022] Open
Abstract
Studying the emergence of topographic organization in sensory maps has been constrained by spatial limitations of traditional anatomical and physiological techniques early in development in many animal models. Here, we have applied a high-resolution, noninvasive, in vivo calcium imaging approach to study the nascent retinotopic map in the larval Xenopus laevis retinotectal system. We performed longitudinal functional imaging of the three-dimensional organization of emerging retinotopic maps and assessed the effects of N-methyl-D-aspartate (NMDA) receptor blockade on map formation. Our results provide insights into early retinotopic map emergence and the role of NMDA receptors in the refinement of topographic gradients. The development of functional topography in the developing brain follows a progression from initially coarse to more precisely organized maps. To examine the emergence of topographically organized maps in the retinotectal system, we performed longitudinal visual receptive field mapping by calcium imaging in the optic tectum of GCaMP6-expressing transgenic Xenopus laevis tadpoles. At stage 42, just 1 d after retinal axons arrived in the optic tectum, a clear retinotopic azimuth map was evident. Animals were imaged over the following week at stages 45 and 48, over which time the tectal neuropil nearly doubled in length and exhibited more precise retinotopic organization. By microinjecting GCaMP6s messenger ribonucleic acid (mRNA) into one blastomere of two-cell stage embryos, we acquired bilateral mosaic tadpoles with GCaMP6s expression in postsynaptic tectal neurons on one side of the animal and in retinal ganglion cell axons crossing to the tectum on the opposite side. Longitudinal observation of retinotopic map emergence revealed the presence of orderly representations of azimuth and elevation as early as stage 42, although presynaptic inputs exhibited relatively less topographic organization than the postsynaptic component for the azimuth axis. Retinotopic gradients in the tectum became smoother between stages 42 and 45. Blocking N-methyl-D-aspartate (NMDA) receptor conductance by rearing tadpoles in MK-801 did not prevent the emergence of retinotopic maps, but it produced more discontinuous topographic gradients and altered receptive field characteristics. These results provide evidence that current through NMDA receptors is dispensable for coarse topographic ordering of retinotectal inputs but does contribute to the fine-scale organization of the retinotectal projection.
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15
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Benfey N, Foubert D, Ruthazer ES. Glia Regulate the Development, Function, and Plasticity of the Visual System From Retina to Cortex. Front Neural Circuits 2022; 16:826664. [PMID: 35177968 PMCID: PMC8843846 DOI: 10.3389/fncir.2022.826664] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/07/2022] [Indexed: 11/13/2022] Open
Abstract
Visual experience is mediated through a relay of finely-tuned neural circuits extending from the retina, to retinorecipient nuclei in the midbrain and thalamus, to the cortex which work together to translate light information entering our eyes into a complex and dynamic spatio-temporal representation of the world. While the experience-dependent developmental refinement and mature function of neurons in each major stage of the vertebrate visual system have been extensively characterized, the contributions of the glial cells populating each region are comparatively understudied despite important findings demonstrating that they mediate crucial processes related to the development, function, and plasticity of the system. In this article we review the mechanisms for neuron-glia communication throughout the vertebrate visual system, as well as functional roles attributed to astrocytes and microglia in visual system development and processing. We will also discuss important aspects of glial function that remain unclear, integrating the knowns and unknowns about glia in the visual system to advance new hypotheses to guide future experimental work.
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16
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Chorghay Z, MacFarquhar D, Li VJ, Aufmkolk S, Schohl A, Wiseman PW, Káradóttir RT, Ruthazer ES. Activity-dependent alteration of early myelin ensheathment in a developing sensory circuit. J Comp Neurol 2021; 530:871-885. [PMID: 34599848 DOI: 10.1002/cne.25253] [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: 07/29/2021] [Revised: 09/26/2021] [Accepted: 09/28/2021] [Indexed: 12/23/2022]
Abstract
Myelination allows for the regulation of conduction velocity, affecting the precise timing of neuronal inputs important for the development and function of brain circuits. In turn, myelination may be altered by changes in experience, neuronal activity, and vesicular release, but the links between sensory experience, corresponding neuronal activity, and resulting alterations in myelination require further investigation. We thus studied the development of myelination in the Xenopus laevis tadpole, a classic model for studies of visual system development and function because it is translucent and visually responsive throughout the formation of its retinotectal system. We begin with a systematic characterization of the timecourse of early myelin ensheathment in the Xenopus retinotectal system using immunohistochemistry of myelin basic protein (MBP) along with third harmonic generation (THG) microscopy, a label-free structural imaging technique. Based on the mid-larval developmental progression of MBP expression in Xenopus, we identified an appropriate developmental window in which to assess the effects of early temporally patterned visual experience on myelin ensheathment. We used calcium imaging of axon terminals in vivo to characterize the responses of retinal ganglion cells over a range of stroboscopic stimulation frequencies. Strobe frequencies that reliably elicited robust versus dampened calcium responses were then presented to animals for 7 d, and differences in the amount of early myelin ensheathment at the optic chiasm were subsequently quantified. This study provides evidence that it is not just the presence but also to the specific temporal properties of sensory stimuli that are important for myelin plasticity.
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Affiliation(s)
- Zahraa Chorghay
- Montreal Neurological Institute-Hospital and Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
| | - David MacFarquhar
- Department of Chemistry, Otto Maass Building, McGill University, Montréal, QC, Canada.,Department of Physics, Otto Maass Building, McGill University, Montréal, QC, Canada
| | - Vanessa J Li
- Montreal Neurological Institute-Hospital and Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
| | - Sarah Aufmkolk
- Montreal Neurological Institute-Hospital and Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada.,Department of Chemistry, Otto Maass Building, McGill University, Montréal, QC, Canada.,Department of Physics, Otto Maass Building, McGill University, Montréal, QC, Canada
| | - Anne Schohl
- Montreal Neurological Institute-Hospital and Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
| | - Paul W Wiseman
- Department of Chemistry, Otto Maass Building, McGill University, Montréal, QC, Canada.,Department of Physics, Otto Maass Building, McGill University, Montréal, QC, Canada
| | - Ragnhildur Thóra Káradóttir
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute and Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.,Department of Physiology, BioMedical Center, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Edward S Ruthazer
- Montreal Neurological Institute-Hospital and Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
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17
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Abstract
Asymmetries in the functional and structural organization of the nervous system are widespread in the animal kingdom and especially characterize the human brain. Although there is little doubt that asymmetries arise through genetic and nongenetic factors, an overarching model to explain the development of functional lateralization patterns is still lacking. Current genetic psychology collects data on genes relevant to brain lateralizations, while animal research provides information on the cellular mechanisms mediating the effects of not only genetic but also environmental factors. This review combines data from human and animal research (especially on birds) and outlines a multi-level model for asymmetry formation. The relative impact of genetic and nongenetic factors varies between different developmental phases and neuronal structures. The basic lateralized organization of a brain is already established through genetically controlled embryonic events. During ongoing development, hemispheric specialization increases for specific functions and subsystems interact to shape the final functional organization of a brain. In particular, these developmental steps are influenced by environmental experiences, which regulate the fine-tuning of neural networks via processes that are referred to as ontogenetic plasticity. The plastic potential of the nervous system could be decisive for the evolutionary success of lateralized brains.
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18
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Temporal regulation of nicotinic acetylcholine receptor subunits supports central cholinergic synapse development in Drosophila. Proc Natl Acad Sci U S A 2021; 118:2004685118. [PMID: 34074746 DOI: 10.1073/pnas.2004685118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The construction and maturation of the postsynaptic apparatus are crucial for synapse and dendrite development. The fundamental mechanisms underlying these processes are most often studied in glutamatergic central synapses in vertebrates. Whether the same principles apply to excitatory cholinergic synapses, such as those found in the insect central nervous system, is not known. To address this question, we investigated a group of projection neurons in the Drosophila larval visual system, the ventral lateral neurons (LNvs), and identified nAchRα1 (Dα1) and nAchRα6 (Dα6) as the main functional nicotinic acetylcholine receptor (nAchR) subunits in the larval LNvs. Using morphological analyses and calcium imaging studies, we demonstrated critical roles of these two subunits in supporting dendrite morphogenesis and synaptic transmission. Furthermore, our RNA sequencing analyses and endogenous tagging approach identified distinct transcriptional controls over the two subunits in the LNvs, which led to the up-regulation of Dα1 and down-regulation of Dα6 during larval development as well as to an activity-dependent suppression of Dα1 Additional functional analyses of synapse formation and dendrite dynamics further revealed a close association between the temporal regulation of individual nAchR subunits and their sequential requirements during the cholinergic synapse maturation. Together, our findings support transcriptional control of nAchR subunits as a core element of developmental and activity-dependent regulation of central cholinergic synapses.
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19
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Experience-Dependent Development of Dendritic Arbors in Mouse Visual Cortex. J Neurosci 2020; 40:6536-6556. [PMID: 32669356 DOI: 10.1523/jneurosci.2910-19.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 12/27/2022] Open
Abstract
The dendritic arbor of neurons constrains the pool of available synaptic partners and influences the electrical integration of synaptic currents. Despite these critical functions, our knowledge of the dendritic structure of cortical neurons during early postnatal development and how these dendritic structures are modified by visual experience is incomplete. Here, we present a large-scale dataset of 849 3D reconstructions of the basal arbor of pyramidal neurons collected across early postnatal development in visual cortex of mice of either sex. We found that the basal arbor grew substantially between postnatal day 7 (P7) and P30, undergoing a 45% increase in total length. However, the gross number of primary neurites and dendritic segments was largely determined by P7. Growth from P7 to P30 occurred primarily through extension of dendritic segments. Surprisingly, comparisons of dark-reared and typically reared mice revealed that a net gain of only 15% arbor length could be attributed to visual experience; most growth was independent of experience. To examine molecular contributions, we characterized the role of the activity-regulated small GTPase Rem2 in both arbor development and the maintenance of established basal arbors. We showed that Rem2 is an experience-dependent negative regulator of dendritic segment number during the visual critical period. Acute deletion of Rem2 reduced directionality of dendritic arbors. The data presented here establish a highly detailed, quantitative analysis of basal arbor development that we believe has high utility both in understanding circuit development as well as providing a framework for computationalists wishing to generate anatomically accurate neuronal models.SIGNIFICANCE STATEMENT Dendrites are the sites of the synaptic connections among neurons. Despite their importance for neural circuit function, only a little is known about the postnatal development of dendritic arbors of cortical pyramidal neurons and the influence of experience. Here we show that the number of primary basal dendritic arbors is already established before eye opening, and that these arbors primarily grow through lengthening of dendritic segments and not through addition of dendritic segments. Surprisingly, visual experience has a modest net impact on overall arbor length (15%). Experiments in KO animals revealed that the gene Rem2 is positive regulator of dendritic length and a negative regulator of dendritic segments.
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20
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Hunt JE, Bruno JR, Pratt KG. An Innate Color Preference Displayed by Xenopus Tadpoles Is Persistent and Requires the Tegmentum. Front Behav Neurosci 2020; 14:71. [PMID: 32477078 PMCID: PMC7235192 DOI: 10.3389/fnbeh.2020.00071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 04/20/2020] [Indexed: 11/26/2022] Open
Abstract
Many animals, especially those that develop externally, are equipped with innate color preferences that promote survival. For example, Xenopus tadpoles are known to phototax most robustly towards mid-spectrum (“green”) wavelengths of light while avoiding shorter (“blue”) wavelengths. The innate preference to phototax towards green likely promotes survival by guiding the tadpoles to green aquatic plants—their source of both food and safety. Here, we characterize the dynamics and circuitry that give rise to this intriguing hard-wired behavior. Using a novel open-field experimental paradigm we found that free-swimming tadpoles indeed spend most of their time in the green portion of the test dish, whether green is pitted against white (brighter than green) or black (darker than green). This preference was modest yet incredibly persistent over time, which, according to the shell game model of predator-prey interactions, minimizes being found by the predator. Furthermore, we found that this innate preference for the color green was experience-independent, and manifested mainly via profoundly slower swimming speeds while in the green region of the test dish. Ablation experiments showed that, at the circuit level, the color-guided swimming behavior requires the tegmentum, but not the optic tectum (OT). Lastly, we determined that exposing tadpoles to the selective serotonin reuptake inhibitor (SSRI) trazodone switched the tadpoles’ preference from color-based to luminance-based, implicating two distinct visual circuits in the tadpole, one that is associated with color-driven behaviors, another associated with luminance-driven behaviors.
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Affiliation(s)
- Jasper Elan Hunt
- Department of Zoology and Physiology and Program in Neuroscience, University of Wyoming, Laramie, WY, United States.,Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - John Rudolph Bruno
- Department of Zoology and Physiology and Program in Neuroscience, University of Wyoming, Laramie, WY, United States
| | - Kara Geo Pratt
- Department of Zoology and Physiology and Program in Neuroscience, University of Wyoming, Laramie, WY, United States
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21
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Robinson S, Courtney MJ. Spatial quantification of the synaptic activity phenotype across large populations of neurons with Markov random fields. Bioinformatics 2019; 34:3196-3204. [PMID: 29897415 DOI: 10.1093/bioinformatics/bty322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 04/25/2018] [Indexed: 11/12/2022] Open
Abstract
Motivation The collective and co-ordinated synaptic activity of large neuronal populations is relevant to neuronal development as well as a range of neurological diseases. Quantification of synaptically-mediated neuronal signalling permits further downstream analysis as well as potential application in target validation and in vitro screening assays. Our aim is to develop a phenotypic quantification for neuronal activity imaging data of large populations of neurons, in particular relating to the spatial component of the activity. Results We extend the use of Markov random field (MRF) models to achieve this aim. In particular, we consider Bayesian posterior densities of model parameters in Gaussian MRFs to directly model changes in calcium fluorescence intensity rather than using spike trains. The basis of our model is defining neuron 'neighbours' by the relative spatial positions of the neuronal somata as obtained from the image data whereas previously this has been limited to defining an artificial square grid across the field of view and spike binning. We demonstrate that our spatial phenotypic quantification is applicable for both in vitro and in vivo data consisting of thousands of neurons over hundreds of time points. We show how our approach provides insight beyond that attained by conventional spike counting and discuss how it could be used to facilitate screening assays for modifiers of disease-associated defects of communication between cells. Availability and implementation We supply the MATLAB code and data to obtain all of the results in the paper. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Sean Robinson
- Department of Mathematics and Statistics, University of Turku, Turku, Finland.,Université Grenoble Alpes, CEA, INSERM, Biology of Cancer and Infection UMR S 1036, Grenoble, France
| | - Michael J Courtney
- Neuronal Signalling Lab, Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland.,Screening Unit, Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, and Institute of Biomedicine, University of Turku, Turku, Finland.,Turku Brain and Mind Center, University of Turku and Åbo Akademi University, Turku, Finland
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22
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Boulanger-Weill J, Sumbre G. Functional Integration of Newborn Neurons in the Zebrafish Optic Tectum. Front Cell Dev Biol 2019; 7:57. [PMID: 31058148 PMCID: PMC6477100 DOI: 10.3389/fcell.2019.00057] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 03/29/2019] [Indexed: 11/15/2022] Open
Abstract
Neurogenesis persists during adulthood in restricted parts of the vertebrate brain. In the optic tectum (OT) of the zebrafish larva, newborn neurons are continuously added and contribute to visual information processing. Recent studies have started to describe the functional development and fate of newborn neurons in the OT. Like the mammalian brain, newborn neurons in the OT require sensory inputs for their integration into local networks and survival. Recent findings suggest that the functional development of newborn neurons requires both activity-dependent and hard-wired mechanisms for proper circuit integration. Here, we review these findings and argue that the study of neurogenesis in non-mammalian species will help elucidate the general mechanisms of circuit assembly following neurogenesis.
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Affiliation(s)
- Jonathan Boulanger-Weill
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA, United States
| | - Germán Sumbre
- Institut de Biologie de l’ENS (IBENS), Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, France
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23
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Petanjek Z, Sedmak D, Džaja D, Hladnik A, Rašin MR, Jovanov-Milosevic N. The Protracted Maturation of Associative Layer IIIC Pyramidal Neurons in the Human Prefrontal Cortex During Childhood: A Major Role in Cognitive Development and Selective Alteration in Autism. Front Psychiatry 2019; 10:122. [PMID: 30923504 PMCID: PMC6426783 DOI: 10.3389/fpsyt.2019.00122] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 02/18/2019] [Indexed: 12/12/2022] Open
Abstract
The human specific cognitive shift starts around the age of 2 years with the onset of self-awareness, and continues with extraordinary increase in cognitive capacities during early childhood. Diffuse changes in functional connectivity in children aged 2-6 years indicate an increase in the capacity of cortical network. Interestingly, structural network complexity does not increase during this time and, thus, it is likely to be induced by selective maturation of a specific neuronal subclass. Here, we provide an overview of a subclass of cortico-cortical neurons, the associative layer IIIC pyramids of the human prefrontal cortex. Their local axonal collaterals are in control of the prefrontal cortico-cortical output, while their long projections modulate inter-areal processing. In this way, layer IIIC pyramids are the major integrative element of cortical processing, and changes in their connectivity patterns will affect global cortical functioning. Layer IIIC neurons have a unique pattern of dendritic maturation. In contrast to other classes of principal neurons, they undergo an additional phase of extensive dendritic growth during early childhood, and show characteristic molecular changes. Taken together, circuits associated with layer IIIC neurons have the most protracted period of developmental plasticity. This unique feature is advanced but also provides a window of opportunity for pathological events to disrupt normal formation of cognitive circuits involving layer IIIC neurons. In this manuscript, we discuss how disrupted dendritic and axonal maturation of layer IIIC neurons may lead into global cortical disconnectivity, affecting development of complex communication and social abilities. We also propose a model that developmentally dictated incorporation of layer IIIC neurons into maturing cortico-cortical circuits between 2 to 6 years will reveal a previous (perinatal) lesion affecting other classes of principal neurons. This "disclosure" of pre-existing functionally silent lesions of other neuronal classes induced by development of layer IIIC associative neurons, or their direct alteration, could be found in different forms of autism spectrum disorders. Understanding the gene-environment interaction in shaping cognitive microcircuitries may be fundamental for developing rehabilitation and prevention strategies in autism spectrum and other cognitive disorders.
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Affiliation(s)
- Zdravko Petanjek
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Dora Sedmak
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Domagoj Džaja
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Ana Hladnik
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Mladen Roko Rašin
- Department of Neuroscience and Cell Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, United States
| | - Nataša Jovanov-Milosevic
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Medical Biology, School of Medicine, University of Zagreb, Zagreb, Croatia
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24
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Sedmak D, Hrvoj-Mihić B, Džaja D, Habek N, Uylings HB, Petanjek Z. Biphasic dendritic growth of dorsolateral prefrontal cortex associative neurons and early cognitive development. Croat Med J 2018. [PMID: 30394011 PMCID: PMC6240825 DOI: 10.3325/cmj.2018.59.189] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Aim To analyze postnatal development and life-span changes of apical dendrite side branches (oblique dendrites) from associative layer IIIC magnopyramidal neurons in the human dorsolateral prefrontal cortex and to compare the findings with the previously established pattern of basal dendrite development. Methods We analyzed dendritic morphology from 352 rapid-Golgi impregnated neurons (10-18 neurons per subject) in Brodmann area 9 from the post-mortem tissue of 25 subjects ranging in age from 1 week to 91 years. Data were collected in the period between 1994 and 1996, and the analysis was performed between September 2017 and February 2018. Quantitative dendritic parameters were statistically analyzed using one-way analysis of variance and two-tailed t tests. Results Oblique dendrites grew rapidly during the first postnatal months, and the increase in the dendrite length was accompanied by the outgrowth of new dendritic segments. After a more than one-year-long “dormant” period of only fine dendritic rearrangements (2.5-16 months), oblique dendrites displayed a second period of marked growth, continuing through the third postnatal year. Basal and oblique dendrites displayed roughly the same growth pattern, but had considerably different topological organization in adulthood. Conclusion Our analysis confirmed that a biphasic pattern of postnatal dendritic development, together with a second growth spurt at the age of 2-3 years, represents a unique feature of the associative layer IIIC magnopyramidal neurons in the human dorsolateral prefrontal cortex. We propose that these structural changes relate to rapid cognitive development during early childhood.
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Affiliation(s)
| | | | | | | | | | - Zdravko Petanjek
- Zdravko Petanjek, Department of Anatomy and Clinical Anatomy, University of Zagreb School of Medicine, Šalata 11, Zagreb, Croatia,
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25
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Gambrill AC, Faulkner RL, McKeown CR, Cline HT. Enhanced visual experience rehabilitates the injured brain in Xenopus tadpoles in an NMDAR-dependent manner. J Neurophysiol 2018; 121:306-320. [PMID: 30517041 DOI: 10.1152/jn.00664.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Traumatic brain injuries introduce functional and structural circuit deficits that must be repaired for an organism to regain function. We developed an injury model in which Xenopus laevis tadpoles are given a penetrating stab wound that damages the optic tectal circuit and impairs visuomotor behavior. In tadpoles, as in other systems, injury induces neurogenesis. The newly generated neurons are thought to integrate into the existing circuit; however, whether they integrate via the same mechanisms that govern normal neuronal maturation during development is not understood. Development of the functional visuomotor circuit in Xenopus is driven by sensory activity. We hypothesized that enhanced visual experience would improve recovery from injury by facilitating integration of newly generated neurons into the tectal circuit. We labeled newly generated neurons in the injured tectum by green fluorescent protein expression and examined their circuit integration using electrophysiology and in vivo imaging. Providing animals with brief bouts of enhanced visual experience starting 24 h after injury increased synaptogenesis and circuit integration of new neurons and facilitated behavioral recovery. To investigate mechanisms of neuronal integration and behavioral recovery after injury, we interfered with N-methyl-d-aspartate (NMDA) receptor function. Ifenprodil, which blocks GluN2B-containing NMDA receptors, impaired dendritic arbor elaboration. GluN2B blockade inhibited functional integration of neurons generated in response to injury and prevented behavioral recovery. Furthermore, tectal GluN2B knockdown blocked the beneficial effects of enhanced visual experience on functional plasticity and behavioral recovery. We conclude that visual experience-mediated rehabilitation of the injured tectal circuit occurs by GluN2B-containing NMDA receptor-dependent integration of newly generated neurons. NEW & NOTEWORTHY Recovery from brain injury is difficult in most systems. The study of regenerative animal models that are capable of injury repair can provide insight into cellular and circuit mechanisms underlying repair. Using Xenopus tadpoles, we show enhanced sensory experience rehabilitates the injured visual circuit and that this experience-dependent recovery depends on N-methyl-d-aspartate receptor function. Understanding the mechanisms of rehabilitation in this system may facilitate recovery in brain regions and systems where repair is currently impossible.
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Affiliation(s)
- Abigail C Gambrill
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Regina L Faulkner
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Caroline R McKeown
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Hollis T Cline
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
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Holley ZL, Bland KM, Casey ZO, Handwerk CJ, Vidal GS. Cross-Regional Gradient of Dendritic Morphology in Isochronically-Sourced Mouse Supragranular Pyramidal Neurons. Front Neuroanat 2018; 12:103. [PMID: 30564104 PMCID: PMC6288488 DOI: 10.3389/fnana.2018.00103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 11/15/2018] [Indexed: 11/13/2022] Open
Abstract
Architectonic heterogeneity in neurons is thought to be important for equipping the mammalian cerebral cortex with an adaptable network that can organize the manifold totality of information it receives. To this end, the dendritic arbors of supragranular pyramidal neurons, even those of the same class, are known to vary substantially. This diversity of dendritic morphology appears to have a rostrocaudal configuration in some brain regions of various species. For example, in humans and non-human primates, neurons in more rostral visual association areas (e.g., V4) tend to have more complex dendritic arbors than those in the caudal primary visual cortex. A rostrocaudal configuration is not so clear in any region of the mouse, which is increasingly being used as a model for neurodevelopmental disorders that arise from dysfunctional cerebral cortical circuits. Therefore, in this study we investigated the complexity of dendritic arbors of neurons distributed throughout a broad area of the mouse cerebral cortex. We reduced selection bias by labeling neurons restricted to become supragranular pyramidal neurons using in utero electroporation. While we observed that the simple rostrocaudal position, cortical depth, or even functional region of a neuron was not directly related to its dendritic morphology, a model that instead included a caudomedial-to-rostrolateral gradient accounted for a significant amount of the observed dendritic morphological variance. In other words, rostrolateral neurons from our data set were generally more complex when compared to caudomedial neurons. Furthermore, dividing the cortex into a visual area and a non-visual area maintained the power of the relationship between caudomedial-to-rostrolateral position and dendritic complexity. Our observations therefore support the idea that dendritic morphology of mouse supragranular excitatory pyramidal neurons across much of the tangential plane of the cerebral cortex is partly shaped by a developmental gradient spanning several functional regions.
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Affiliation(s)
- Zachary Logan Holley
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | - Katherine M Bland
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | - Zachary O Casey
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | | | - George S Vidal
- Department of Biology, James Madison University, Harrisonburg, VA, United States
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Sedmak D, Hrvoj-Mihić B, Džaja D, Habek N, Uylings HB, Petanjek Z. Biphasic dendritic growth of dorsolateral prefrontal cortex associative neurons and early cognitive development. Croat Med J 2018; 59:189-202. [PMID: 30394011 PMCID: PMC6240825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 10/31/2018] [Indexed: 10/05/2023] Open
Abstract
AIM To analyze postnatal development and life-span changes of apical dendrite side branches (oblique dendrites) from associative layer IIIC magnopyramidal neurons in the human dorsolateral prefrontal cortex and to compare the findings with the previously established pattern of basal dendrite development. METHODS We analyzed dendritic morphology from 352 rapid-Golgi impregnated neurons (10-18 neurons per subject) in Brodmann area 9 from the post-mortem tissue of 25 subjects ranging in age from 1 week to 91 years. Data were collected in the period between 1994 and 1996, and the analysis was performed between September 2017 and February 2018. Quantitative dendritic parameters were statistically analyzed using one-way analysis of variance and two-tailed t tests. RESULTS Oblique dendrites grew rapidly during the first postnatal months, and the increase in the dendrite length was accompanied by the outgrowth of new dendritic segments. After a more than one-year-long "dormant" period of only fine dendritic rearrangements (2.5-16 months), oblique dendrites displayed a second period of marked growth, continuing through the third postnatal year. Basal and oblique dendrites displayed roughly the same growth pattern, but had considerably different topological organization in adulthood. CONCLUSION Our analysis confirmed that a biphasic pattern of postnatal dendritic development, together with a second growth spurt at the age of 2-3 years, represents a unique feature of the associative layer IIIC magnopyramidal neurons in the human dorsolateral prefrontal cortex. We propose that these structural changes relate to rapid cognitive development during early childhood.
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Affiliation(s)
| | | | | | | | | | - Zdravko Petanjek
- Zdravko Petanjek, Department of Anatomy and Clinical Anatomy, University of Zagreb School of Medicine, Šalata 11, Zagreb, Croatia,
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Gambrill AC, Faulkner RL, Cline HT. Direct intertectal inputs are an integral component of the bilateral sensorimotor circuit for behavior in Xenopus tadpoles. J Neurophysiol 2018; 119:1947-1961. [PMID: 29442555 DOI: 10.1152/jn.00051.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The circuit controlling visually guided behavior in nonmammalian vertebrates, such as Xenopus tadpoles, includes retinal projections to the contralateral optic tectum, where visual information is processed, and tectal motor outputs projecting ipsilaterally to hindbrain and spinal cord. Tadpoles have an intertectal commissure whose function is unknown, but it might transfer information between the tectal lobes. Differences in visual experience between the two eyes have profound effects on the development and function of visual circuits in animals with binocular vision, but the effects on animals with fully crossed retinal projections are not clear. We tested the effect of monocular visual experience on the visuomotor circuit in Xenopus tadpoles. We show that cutting the intertectal commissure or providing visual experience to one eye (monocular visual experience) is sufficient to disrupt tectally mediated visual avoidance behavior. Monocular visual experience induces asymmetry in tectal circuit activity across the midline. Repeated exposure to monocular visual experience drives maturation of the stimulated retinotectal synapses, seen as increased AMPA-to-NMDA ratios, induces synaptic plasticity in intertectal synaptic connections, and induces bilaterally asymmetric changes in the tectal excitation-to-inhibition ratio (E/I). We show that unilateral expression of peptides that interfere with AMPA or GABAA receptor trafficking alters E/I in the transfected tectum and is sufficient to degrade visuomotor behavior. Our study demonstrates that monocular visual experience in animals with fully crossed visual systems produces asymmetric circuit function across the midline and degrades visuomotor behavior. The data further suggest that intertectal inputs are an integral component of a bilateral visuomotor circuit critical for behavior. NEW & NOTEWORTHY The developing optic tectum of Xenopus tadpoles represents a unique circuit in which laterally positioned eyes provide sensory input to a circuit that is transiently monocular, but which will be binocular in the animal's adulthood. We challenge the idea that the two lobes of tadpole optic tectum function independently by testing the requirement of interhemispheric communication and demonstrate that unbalanced sensory input can induce structural and functional plasticity in the tectum sufficient to disrupt function.
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Affiliation(s)
- Abigail C Gambrill
- Department of Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Regina L Faulkner
- Department of Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Hollis T Cline
- Department of Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
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Neural electrical activity and neural network growth. Neural Netw 2018; 101:15-24. [PMID: 29475142 DOI: 10.1016/j.neunet.2018.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 01/19/2023]
Abstract
The development of central and peripheral neural system depends in part on the emergence of the correct functional connectivity in its input and output pathways. Now it is generally accepted that molecular factors guide neurons to establish a primary scaffold that undergoes activity-dependent refinement for building a fully functional circuit. However, a number of experimental results obtained recently shows that the neuronal electrical activity plays an important role in the establishing of initial interneuronal connections. Nevertheless, these processes are rather difficult to study experimentally, due to the absence of theoretical description and quantitative parameters for estimation of the neuronal activity influence on growth in neural networks. In this work we propose a general framework for a theoretical description of the activity-dependent neural network growth. The theoretical description incorporates a closed-loop growth model in which the neural activity can affect neurite outgrowth, which in turn can affect neural activity. We carried out the detailed quantitative analysis of spatiotemporal activity patterns and studied the relationship between individual cells and the network as a whole to explore the relationship between developing connectivity and activity patterns. The model, developed in this work will allow us to develop new experimental techniques for studying and quantifying the influence of the neuronal activity on growth processes in neural networks and may lead to a novel techniques for constructing large-scale neural networks by self-organization.
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Visual Experience Facilitates BDNF-Dependent Adaptive Recruitment of New Neurons in the Postembryonic Optic Tectum. J Neurosci 2018; 38:2000-2014. [PMID: 29363581 DOI: 10.1523/jneurosci.1962-17.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 01/08/2018] [Accepted: 01/15/2018] [Indexed: 01/11/2023] Open
Abstract
Postembryonic brain development is sensitive to environmental input and sensory experience, but the mechanisms underlying healthy adaptive brain growth are poorly understood. Here, we tested the importance of visual experience on larval zebrafish (Danio rerio) postembryonic development of the optic tectum (OT), a midbrain structure involved in visually guided behavior. We first characterized postembryonic neurogenic growth in OT, in which new neurons are generated along the caudal tectal surface and contribute appositionally to anatomical growth. Restricting visual experience during development by rearing larvae in dim light impaired OT anatomical and neurogenic growth, specifically by reducing the survival of new neurons in the medial periventricular gray zone. Neuronal survival in the OT was reduced only when visual experience was restricted for the first 5 d following new neuron generation, suggesting that tectal neurons exhibit an early sensitive period in which visual experience protects these cells from subsequent neuronal loss. The effect of dim rearing on neuronal survival was mimicked by treatment with an NMDA receptor antagonist early, but not later, in a new neuron's life. Both dim rearing and antagonist treatment reduced BDNF production in the OT, and supplementing larvae with exogenous BDNF during dim rearing prevented neuronal loss, suggesting that visual experience protects new tectal neurons through neural activity-dependent BDNF expression. Collectively, we present evidence for a sensitive period of neurogenic adaptive growth in the larval zebrafish OT that relies on visual experience-dependent mechanisms.SIGNIFICANCE STATEMENT Early brain development is shaped by environmental factors via sensory input; however, this form of experience-dependent neuroplasticity is traditionally studied as structural and functional changes within preexisting neurons. Here, we found that restricting visual experience affects development of the larval zebrafish optic tectum, a midbrain structure involved in visually guided behavior, by limiting the survival of newly generated neurons. We found that new tectal neurons exhibit a sensitive period soon after cell birth in which adequate visual experience, likely mediated by neuronal activity driving BDNF production within the tectum, would protect them from subsequent neuronal loss over the following week. Collectively, we present evidence for neurogenic adaptive tectal growth under different environmental lighting conditions.
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Boulanger-Weill J, Candat V, Jouary A, Romano SA, Pérez-Schuster V, Sumbre G. Functional Interactions between Newborn and Mature Neurons Leading to Integration into Established Neuronal Circuits. Curr Biol 2017; 27:1707-1720.e5. [PMID: 28578928 PMCID: PMC5483231 DOI: 10.1016/j.cub.2017.05.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 04/03/2017] [Accepted: 05/09/2017] [Indexed: 02/02/2023]
Abstract
From development up to adulthood, the vertebrate brain is continuously supplied with newborn neurons that integrate into established mature circuits. However, how this process is coordinated during development remains unclear. Using two-photon imaging, GCaMP5 transgenic zebrafish larvae, and sparse electroporation in the larva's optic tectum, we monitored spontaneous and induced activity of large neuronal populations containing newborn and functionally mature neurons. We observed that the maturation of newborn neurons is a 4-day process. Initially, newborn neurons showed undeveloped dendritic arbors, no neurotransmitter identity, and were unresponsive to visual stimulation, although they displayed spontaneous calcium transients. Later on, newborn-labeled neurons began to respond to visual stimuli but in a very variable manner. At the end of the maturation period, newborn-labeled neurons exhibited visual tuning curves (spatial receptive fields and direction selectivity) and spontaneous correlated activity with neighboring functionally mature neurons. At this developmental stage, newborn-labeled neurons presented complex dendritic arbors and neurotransmitter identity (excitatory or inhibitory). Removal of retinal inputs significantly perturbed the integration of newborn neurons into the functionally mature tectal network. Our results provide a comprehensive description of the maturation of newborn neurons during development and shed light on potential mechanisms underlying their integration into a functionally mature neuronal circuit.
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Affiliation(s)
- 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
| | - Adrien Jouary
- 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; Instituto de Investigación en Biomedicina de Buenos Aires - CONICET - Partner Institute of the Max Planck Society, 1428 Buenos Aires, Argentina
| | - Verónica Pérez-Schuster
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France; Laboratorio de Neurobiología de la Memoria, Departamento Fisiología, Biología Molecular y Celular, FCEyN, UBA and IFIBYNE-CONICET, Ciudad Universitaria, 1428 Buenos Aires, Argentina; Departamento de Física, FCEyN, UBA and IFIBA-CONICET, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - Germán Sumbre
- IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France.
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Vonhoff F, Keshishian H. Activity-Dependent Synaptic Refinement: New Insights from Drosophila. Front Syst Neurosci 2017; 11:23. [PMID: 28484377 PMCID: PMC5399093 DOI: 10.3389/fnsys.2017.00023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/03/2017] [Indexed: 01/26/2023] Open
Abstract
During development, neurons establish inappropriate connections as they seek out their synaptic partners, resulting in supernumerary synapses that must be pruned away. The removal of miswired synapses usually involves electrical activity, often through a Hebbian spike-timing mechanism. A novel form of activity-dependent refinement is used by Drosophila that may be non-Hebbian, and is critical for generating the precise connectivity observed in that system. In Drosophila, motoneurons use both glutamate and the biogenic amine octopamine for neurotransmission, and the muscle fibers receive multiple synaptic inputs. Motoneuron growth cones respond in a time-regulated fashion to multiple chemotropic signals arising from their postsynaptic partners. Central to this mechanism is a very low frequency (<0.03 Hz) oscillation of presynaptic cytoplasmic calcium, that regulates and coordinates the action of multiple downstream effectors involved in the withdrawal from off-target contacts. Low frequency calcium oscillations are widely observed in developing neural circuits in mammals, and have been shown to be critical for normal connectivity in a variety of neural systems. In Drosophila these mechanisms allow the growth cone to sample widely among possible synaptic partners, evaluate opponent chemotropic signals, and withdraw from off-target contacts. It is possible that the underlying molecular mechanisms are conserved widely among invertebrates and vertebrates.
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Affiliation(s)
- Fernando Vonhoff
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
| | - Haig Keshishian
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
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Kutsarova E, Munz M, Ruthazer ES. Rules for Shaping Neural Connections in the Developing Brain. Front Neural Circuits 2017; 10:111. [PMID: 28119574 PMCID: PMC5223306 DOI: 10.3389/fncir.2016.00111] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/16/2016] [Indexed: 11/13/2022] Open
Abstract
It is well established that spontaneous activity in the developing mammalian brain plays a fundamental role in setting up the precise connectivity found in mature sensory circuits. Experiments that produce abnormal activity or that systematically alter neural firing patterns during periods of circuit development strongly suggest that the specific patterns and the degree of correlation in firing may contribute in an instructive manner to circuit refinement. In fish and amphibians, unlike amniotic vertebrates, sensory input directly drives patterned activity during the period of initial projection outgrowth and innervation. Experiments combining sensory stimulation with live imaging, which can be performed non-invasively in these simple vertebrate models, have provided important insights into the mechanisms by which neurons read out and respond to activity patterns. This article reviews the classic and recent literature on spontaneous and evoked activity-dependent circuit refinement in sensory systems and formalizes a set of mechanistic rules for the transformation of patterned activity into accurate neuronal connectivity in the developing brain.
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Affiliation(s)
- Elena Kutsarova
- Montreal Neurological Institute, McGill University Montreal, QC, Canada
| | - Martin Munz
- Friedrich Miescher Institute, Neurobiology Group Basel, Switzerland
| | - Edward S Ruthazer
- Montreal Neurological Institute, McGill University Montreal, QC, Canada
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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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Gambrill AC, Faulkner R, Cline HT. Experience-dependent plasticity of excitatory and inhibitory intertectal inputs in Xenopus tadpoles. J Neurophysiol 2016; 116:2281-2297. [PMID: 27582296 DOI: 10.1152/jn.00611.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 08/29/2016] [Indexed: 01/11/2023] Open
Abstract
Communication between optic tecta/superior colliculi is thought to be required for sensorimotor behaviors by comparing inputs across the midline, however the development of and the role of visual experience in the function and plasticity of intertectal connections are unclear. We combined neuronal tracing, in vivo time-lapse imaging, and electrophysiology to characterize the structural and functional development of intertectal axons and synapses in Xenopus tadpole optic tectum. We find that intertectal connections are established early during optic tectal circuit development. We determined the neurotransmitter identity of intertectal neurons using both rabies virus-mediated tracing combined with post-hoc immunohistochemistry, and electrophysiology. Excitatory and inhibitory intertectal neuronal somata are similarly distributed throughout the tectum. Excitatory and inhibitory intertectal axons are structurally similar and elaborate broadly in the contralateral tectum. We demonstrate that intertectal and retinotectal axons converge onto tectal neurons by recording postsynaptic currents after stimulating intertectal and retinotectal inputs. Cutting the intertectal commissure removes synaptic responses to contralateral tectal stimulation. In vivo time-lapse imaging demonstrated that visual experience drives plasticity in intertectal bouton size and dynamics. Finally, visual experience coordinately drives the maturation of excitatory and inhibitory intertectal inputs by increasing AMPA- and GABA-receptor mediated currents, comparable to experience-dependent maturation of retinotectal inputs. These data indicate that visual experience regulates plasticity of excitatory and inhibitory intertectal inputs, maintaining the excitatory: inhibitory ratio of intertectal input. These studies place intertectal inputs as key players in tectal circuit development and suggest that they may play a role in sensory information processing critical to sensorimotor behaviors.
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