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Jenks KR, Cai Y, Nayan ME, Tsimring K, Li K, Zepeda JC, Heller GR, Delepine C, Shih J, Yuan S, Zhu Y, Wang Y, Duan Y, Fu AKY, Ku T, Yun DH, Chung K, Zhang C, Boyden ES, Mellios N, Sur M, Kan Ip JP. The noncoding circular RNA circHomer1 regulates developmental experience-dependent plasticity in mouse visual cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.19.603416. [PMID: 39091722 PMCID: PMC11291094 DOI: 10.1101/2024.07.19.603416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Circular RNAs (circRNAs) are noncoding RNAs abundant in brain tissue, and many are derived from activity-dependent, linear mRNAs encoding for synaptic proteins, suggesting that circRNAs may directly or indirectly play a role in regulating synaptic development, plasticity, and function. However, it is unclear if the circular forms of these RNAs are similarly regulated by activity and what role these circRNAs play in developmental plasticity. Here, we employed transcriptome-wide analysis comparing differential expression of both mRNAs and circRNAs in juvenile mouse primary visual cortex (V1) following monocular deprivation (MD), a model of developmental plasticity. Among the differentially expressed mRNAs and circRNAs following 3-day MD, the circular and the activity-dependent linear forms of the Homer1 gene, circHomer1 and Homer1a respectively, were of interest as their expression changed in opposite directions: circHomer1 expression increased while the expression of Homer1a decreased following MD. Knockdown of circHomer1 prevented the depression of closed-eye responses normally observed after 3-day MD. circHomer1-knockdown led to a reduction in average dendritic spine size prior to MD, but critically there was no further reduction after 3-day MD, consistent with impaired structural plasticity. circHomer1-knockdown also prevented the reduction of surface AMPA receptors after 3-day MD. Synapse-localized puncta of the AMPA receptor endocytic protein Arc increased in volume after MD but were smaller in circHomer1-knockdown neurons, suggesting that circHomer1 regulates plasticity through mechanisms of activity-dependent AMPA receptor endocytosis. Thus, activity-dependent circRNAs regulate developmental synaptic plasticity, and our findings highlight the essential role of circHomer1 in V1 plasticity induced by short-term MD.
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Affiliation(s)
- Kyle R. Jenks
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Ying Cai
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Marvin Eduarte Nayan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
- Gerald Choa Neuroscience Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Katya Tsimring
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Keji Li
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - José C. Zepeda
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Gregg R. Heller
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Chloe Delepine
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Jennifer Shih
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Shiyang Yuan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Yao Zhu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ye Wang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yangyang Duan
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Amy K. Y. Fu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Taeyun Ku
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Dae Hee Yun
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Kwanghun Chung
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Chi Zhang
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Edward S. Boyden
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
- Howard Hughes Medical Institute, Cambridge, Massachusetts, 02139, USA
| | - Nikolaos Mellios
- Circular Genomics Inc, Albuquerque, New Mexico, 87110, USA
- Previously at: University of New Mexico, Department of Neurosciences, Albuquerque, New Mexico, 87131, USA
| | - Mriganka Sur
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Jacque Pak Kan Ip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Gerald Choa Neuroscience Institute, The Chinese University of Hong Kong, Hong Kong, China
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Xie Y, Wang R, McClatchy DB, Ma Y, Diedrich J, Sanchez-Alavez M, Petrascheck M, Yates JR, Cline HT. Activity-dependent synthesis of Emerin gates neuronal plasticity by regulating proteostasis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.30.600712. [PMID: 38979362 PMCID: PMC11230442 DOI: 10.1101/2024.06.30.600712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Neurons dynamically regulate their proteome in response to sensory input, a key process underlying experience-dependent plasticity. We characterized the visual experience-dependent nascent proteome within a brief, defined time window after stimulation using an optimized metabolic labeling approach. Visual experience induced cell type-specific and age-dependent alterations in the nascent proteome, including proteostasis-related processes. We identified Emerin as the top activity-induced candidate plasticity protein and demonstrated that its rapid activity-induced synthesis is transcription-independent. In contrast to its nuclear localization and function in myocytes, activity-induced neuronal Emerin is abundant in the endoplasmic reticulum and broadly inhibits protein synthesis, including translation regulators and synaptic proteins. Downregulating Emerin shifted the dendritic spine population from predominantly mushroom morphology to filopodia and decreased network connectivity. In mice, decreased Emerin reduced visual response magnitude and impaired visual information processing. Our findings support an experience-dependent feed-forward role for Emerin in temporally gating neuronal plasticity by negatively regulating translation.
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Chalmers N, Masouti E, Beckervordersandforth R. Astrocytes in the adult dentate gyrus-balance between adult and developmental tasks. Mol Psychiatry 2024; 29:982-991. [PMID: 38177351 PMCID: PMC11176073 DOI: 10.1038/s41380-023-02386-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024]
Abstract
Astrocytes, a major glial cell type in the brain, are indispensable for the integration, maintenance and survival of neurons during development and adulthood. Both life phases make specific demands on the molecular and physiological properties of astrocytes, and most research projects traditionally focus on either developmental or adult astrocyte functions. In most brain regions, the generation of brain cells and the establishment of neural circuits ends with postnatal development. However, few neurogenic niches exist in the adult brain in which new neurons and glial cells are produced lifelong, and the integration of new cells into functional circuits represent a very special form of plasticity. Consequently, in the neurogenic niche, the astrocytes must be equipped to execute both mature and developmental tasks in order to integrate newborn neurons into the circuit and yet maintain overall homeostasis without affecting the preexisting neurons. In this review, we focus on astrocytes of the hippocampal dentate gyrus (DG), and discuss specific features of the astrocytic compartment that may allow the execution of both tasks. Firstly, astrocytes of the adult DG are molecularly, morphologically and functionally diverse, and the distinct astrocytes subtypes are characterized by their localization to DG layers. This spatial separation may lead to a functional specification of astrocytes subtypes according to the neuronal structures they are embedded in, hence a division of labor. Secondly, the astrocytic compartment is not static, but steadily increasing in numbers due to lifelong astrogenesis. Interestingly, astrogenesis can adapt to environmental and behavioral stimuli, revealing an unexpected astrocyte dynamic that allows the niche to adopt to changing demands. The diversity and dynamic of astrocytes in the adult DG implicate a vital contribution to hippocampal plasticity and represent an interesting model to uncover mechanisms how astrocytes simultaneously fulfill developmental and adult tasks.
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Affiliation(s)
- Nicholas Chalmers
- Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Evangelia Masouti
- Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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4
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Song T, Duan X. Ocular dominance in cataract surgery: research status and progress. Graefes Arch Clin Exp Ophthalmol 2024; 262:33-41. [PMID: 37644327 DOI: 10.1007/s00417-023-06216-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 08/17/2023] [Accepted: 08/21/2023] [Indexed: 08/31/2023] Open
Abstract
Ocular dominance (OD), a commonly used concept in clinical practice, plays an important role in optometry and refractive surgery. With the development of refractive cataract surgery, the refractive function of the intraocular lens determines the achievement of the postoperative full range of vision based on the retinal defocus blur suppression and binocular monovision principle. Therefore, OD plays an important role in cataract surgery. OD is related to the visual formation of the cerebral cortex, and its plasticity suggests that visual experience can influence the visual system. Cataract surgery changes the visual experience and transforms the dominant eye, which confirms the plasticity of the visual system. Based on the concept and mechanism of OD, this review summarizes the application of OD in cataract surgery.
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Affiliation(s)
- Tingting Song
- Jinan University, Guangzhou, China
- Changsha Aier Eye Hospital, Aier Eye Hospital Group, Tianxin District, 188 Furong South Road, Changsha, 410009, China
| | - Xuanchu Duan
- Jinan University, Guangzhou, China.
- Changsha Aier Eye Hospital, Aier Eye Hospital Group, Tianxin District, 188 Furong South Road, Changsha, 410009, China.
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Hageter J, Starkey J, Horstick EJ. Thalamic regulation of a visual critical period and motor behavior. Cell Rep 2023; 42:112287. [PMID: 36952349 PMCID: PMC10514242 DOI: 10.1016/j.celrep.2023.112287] [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: 10/14/2022] [Revised: 02/02/2023] [Accepted: 03/03/2023] [Indexed: 03/24/2023] Open
Abstract
During the visual critical period (CP), sensory experience refines the structure and function of visual circuits. The basis of this plasticity was long thought to be limited to cortical circuits, but recently described thalamic plasticity challenges this dogma and demonstrates greater complexity underlying visual plasticity. Yet how visual experience modulates thalamic neurons or how the thalamus modulates CP timing is incompletely understood. Using a larval zebrafish, thalamus-centric ocular dominance model, we show functional changes in the thalamus and a role of inhibitory signaling to establish CP timing using a combination of functional imaging, optogenetics, and pharmacology. Hemisphere-specific changes in genetically defined thalamic neurons correlate with changes in visuomotor behavior, establishing a role of thalamic plasticity in modulating motor performance. Our work demonstrates that visual plasticity is broadly conserved and that visual experience leads to neuron-level functional changes in the thalamus that require inhibitory signaling to establish critical period timing.
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Affiliation(s)
- John Hageter
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA
| | - Jacob Starkey
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA
| | - Eric J Horstick
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA; Department of Neuroscience, West Virginia University, Morgantown, WV 26506, USA.
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6
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Marin IA, Gutman-Wei AY, Chew KS, Raissi AJ, Djurisic M, Shatz CJ. The nonclassical MHC class I Qa-1 expressed in layer 6 neurons regulates activity-dependent plasticity via microglial CD94/NKG2 in the cortex. Proc Natl Acad Sci U S A 2022; 119:e2203965119. [PMID: 35648829 PMCID: PMC9191652 DOI: 10.1073/pnas.2203965119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 04/20/2022] [Indexed: 12/30/2022] Open
Abstract
During developmental critical periods, circuits are sculpted by a process of activity-dependent competition. The molecular machinery involved in regulating the complex process of responding to different levels of activity is now beginning to be identified. Here, we show that the nonclassical major histocompatibility class I (MHCI) molecule Qa-1 is expressed in the healthy brain in layer 6 corticothalamic neurons. In the visual cortex, Qa-1 expression begins during the critical period for ocular dominance (OD) plasticity and is regulated by neuronal activity, suggesting a role in regulating activity-dependent competition. Indeed, in mice lacking Qa-1, OD plasticity is perturbed. Moreover, signaling through CD94/NKG2, a known cognate Qa-1 heterodimeric receptor in the immune system, is implicated: selectively targeting this interaction phenocopies the plasticity perturbation observed in Qa-1 knockouts. In the cortex, CD94/NKG2 is expressed by microglial cells, which undergo activity-dependent changes in their morphology in a Qa-1–dependent manner. Our study thus reveals a neuron–microglial interaction dependent upon a nonclassical MHCI molecule expressed in L6 neurons, which regulates plasticity in the visual cortex. These results also point to an unexpected function for the Qa-1/HLA-E (ligand) and CD94/NKG2 (receptor) interaction in the nervous system, in addition to that described in the immune system.
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Affiliation(s)
- Ioana A. Marin
- Department of Biology, Stanford University, Stanford, CA 94035
- Department of Neurobiology, Stanford University, Stanford, CA 94035
| | - Alan Y. Gutman-Wei
- Department of Biology, Stanford University, Stanford, CA 94035
- Department of Neurobiology, Stanford University, Stanford, CA 94035
| | - Kylie S. Chew
- Department of Biology, Stanford University, Stanford, CA 94035
- Department of Neurobiology, Stanford University, Stanford, CA 94035
| | - Aram J. Raissi
- Department of Biology, Stanford University, Stanford, CA 94035
- Department of Neurobiology, Stanford University, Stanford, CA 94035
| | - Maja Djurisic
- Department of Biology, Stanford University, Stanford, CA 94035
- Department of Neurobiology, Stanford University, Stanford, CA 94035
| | - Carla J. Shatz
- Department of Biology, Stanford University, Stanford, CA 94035
- Department of Neurobiology, Stanford University, Stanford, CA 94035
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7
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Renouard L, Hayworth C, Rempe M, Clegern W, Wisor J, Frank MG. REM sleep promotes bidirectional plasticity in developing visual cortex in vivo. Neurobiol Sleep Circadian Rhythms 2022; 12:100076. [PMID: 35592144 PMCID: PMC9112011 DOI: 10.1016/j.nbscr.2022.100076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/20/2022] [Accepted: 04/28/2022] [Indexed: 11/23/2022] Open
Abstract
Sleep is required for the full expression of plasticity during the visual critical period (CP). However, the precise role of rapid-eye-movement (REM) sleep in this process is undetermined. Previous studies in rodents indicate that REM sleep weakens cortical circuits following MD, but this has been explored in only one class of cortical neuron (layer 5 apical dendrites). We investigated the role of REM sleep in ocular dominance plasticity (ODP) in layer 2/3 neurons using 2-photon calcium imaging in awake CP mice. In contrast to findings in layer 5 neurons, we find that REM sleep promotes changes consistent with synaptic strengthening and weakening. This supports recent suggestions that the effects of sleep on plasticity are highly dependent upon the type of circuit and preceding waking experience.
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Affiliation(s)
- Leslie Renouard
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, HSB 280M, Spokane, WA, 99223, USA
| | - Christopher Hayworth
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, HSB 280M, Spokane, WA, 99223, USA
| | - Michael Rempe
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, HSB 280M, Spokane, WA, 99223, USA
| | - Will Clegern
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, HSB 280M, Spokane, WA, 99223, USA
| | - Jonathan Wisor
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, HSB 280M, Spokane, WA, 99223, USA
| | - Marcos G. Frank
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, HSB 280M, Spokane, WA, 99223, USA
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8
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Zhu Y, Wang MJ, Crawford KM, Ramírez-Tapia JC, Lussier AA, Davis KA, de Leeuw C, Takesian AE, Hensch TK, Smoller JW, Dunn EC. Sensitive period-regulating genetic pathways and exposure to adversity shape risk for depression. Neuropsychopharmacology 2022; 47:497-506. [PMID: 34689167 PMCID: PMC8674315 DOI: 10.1038/s41386-021-01172-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 07/23/2021] [Accepted: 08/30/2021] [Indexed: 01/03/2023]
Abstract
Animal and human studies have documented the existence of developmental windows (or sensitive periods) when experience can have lasting effects on brain structure or function, behavior, and disease. Although sensitive periods for depression likely arise through a complex interplay of genes and experience, this possibility has not yet been explored in humans. We examined the effect of genetic pathways regulating sensitive periods, alone and in interaction with common childhood adversities, on depression risk. Guided by a translational approach, we: (1) performed association analyses of three gene sets (60 genes) shown in animal studies to regulate sensitive periods using summary data from a genome-wide association study of depression (n = 807,553); (2) evaluated the developmental expression patterns of these genes using data from BrainSpan (n = 31), a transcriptional atlas of postmortem brain samples; and (3) tested gene-by-development interplay (dGxE) by analyzing the combined effect of common variants in sensitive period genes and time-varying exposure to two types of childhood adversity within a population-based birth cohort (n = 6254). The gene set regulating sensitive period opening associated with increased depression risk. Notably, 6 of the 15 genes in this set showed developmentally regulated gene-level expression. We also identified a statistical interaction between caregiver physical or emotional abuse during ages 1-5 years and genetic risk for depression conferred by the opening genes. Genes involved in regulating sensitive periods are differentially expressed across the life course and may be implicated in depression vulnerability. Our findings about gene-by-development interplay motivate further research in large, more diverse samples to further unravel the complexity of depression etiology through a sensitive period lens.
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Affiliation(s)
- Yiwen Zhu
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
| | - Min-Jung Wang
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | | | | | - Alexandre A Lussier
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
- Center for Brain Science, Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Kathryn A Davis
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Christiaan de Leeuw
- Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Department of Complex Trait Genetics, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Anne E Takesian
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear and Department of Otorhinolaryngology and Head/Neck Surgery, Harvard Medical School, Boston, MA, USA
| | - Takao K Hensch
- Center for Brain Science, Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jordan W Smoller
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
- Stanley Center for Psychiatric Research, The Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Erin C Dunn
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
- Stanley Center for Psychiatric Research, The Broad Institute of Harvard and MIT, Cambridge, MA, USA.
- Harvard Center on the Developing Child, Cambridge, MA, USA.
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9
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Jenks KR, Tsimring K, Ip JPK, Zepeda JC, Sur M. Heterosynaptic Plasticity and the Experience-Dependent Refinement of Developing Neuronal Circuits. Front Neural Circuits 2021; 15:803401. [PMID: 34949992 PMCID: PMC8689143 DOI: 10.3389/fncir.2021.803401] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/15/2021] [Indexed: 01/01/2023] Open
Abstract
Neurons remodel the structure and strength of their synapses during critical periods of development in order to optimize both perception and cognition. Many of these developmental synaptic changes are thought to occur through synapse-specific homosynaptic forms of experience-dependent plasticity. However, homosynaptic plasticity can also induce or contribute to the plasticity of neighboring synapses through heterosynaptic interactions. Decades of research in vitro have uncovered many of the molecular mechanisms of heterosynaptic plasticity that mediate local compensation for homosynaptic plasticity, facilitation of further bouts of plasticity in nearby synapses, and cooperative induction of plasticity by neighboring synapses acting in concert. These discoveries greatly benefited from new tools and technologies that permitted single synapse imaging and manipulation of structure, function, and protein dynamics in living neurons. With the recent advent and application of similar tools for in vivo research, it is now feasible to explore how heterosynaptic plasticity contribute to critical periods and the development of neuronal circuits. In this review, we will first define the forms heterosynaptic plasticity can take and describe our current understanding of their molecular mechanisms. Then, we will outline how heterosynaptic plasticity may lead to meaningful refinement of neuronal responses and observations that suggest such mechanisms are indeed at work in vivo. Finally, we will use a well-studied model of cortical plasticity—ocular dominance plasticity during a critical period of visual cortex development—to highlight the molecular overlap between heterosynaptic and developmental forms of plasticity, and suggest potential avenues of future research.
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Affiliation(s)
- Kyle R Jenks
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Katya Tsimring
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Jacque Pak Kan Ip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Jose C Zepeda
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Mriganka Sur
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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10
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Chan J, Hao X, Liu Q, Cang J, Gu Y. Closing the Critical Period Is Required for the Maturation of Binocular Integration in Mouse Primary Visual Cortex. Front Cell Neurosci 2021; 15:749265. [PMID: 34899187 PMCID: PMC8663722 DOI: 10.3389/fncel.2021.749265] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 10/21/2021] [Indexed: 11/25/2022] Open
Abstract
Binocular matching of orientation preference between the two eyes is a common form of binocular integration that is regarded as the basis for stereopsis. How critical period plasticity enables binocular matching under the guidance of normal visual experience has not been fully demonstrated. To investigate how critical period closure affects the binocular matching, a critical period prolonged mouse model was constructed through the administration of bumetanide, an NKCC1 transporter antagonist. Using acute in vivo extracellular recording and molecular assay, we revealed that binocular matching was transiently disrupted due to heightened plasticity after the normal critical period, together with an increase in the density of spines and synapses, and the upregulation of GluA1 expression. Diazepam (DZ)/[(R, S)-3-(2-carboxypiperazin-4-yl) propyl-1-phosphonic acid (CPP)] could reclose the extended critical period, and rescue the deficits in binocular matching. Furthermore, the extended critical period, alone, with normal visual experience is sufficient for the completion of binocular matching in amblyopic mice. Similarly, prolonging the critical period into adulthood by knocking out Nogo-66 receptor can prevent the normal maturation of binocular matching and depth perception. These results suggest that maintaining an optimal plasticity level during adolescence is most beneficial for the systemic maturation. Extending the critical period provides new clues for the maturation of binocular vision and may have critical implications for the treatment of amblyopia.
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Affiliation(s)
- Jiangping Chan
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Xiangwen Hao
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Qiong Liu
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China.,School of Life Sciences, Westlake University, Hangzhou, China
| | - Jianhua Cang
- Department of Biology, University of Virginia, Charlottesville, VA, United States.,Department of Psychology, University of Virginia, Charlottesville, VA, United States
| | - Yu Gu
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
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11
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Bi AL, Zhang YY, Lu ZY, Tang HY, Zhang XY, Zhang ZH, Li BQ, Guo DD, Gong S, Li Q, Wang XR, Lu XZ, Bi HS. Synaptosomal Actin Dynamics in the Developmental Visual Cortex Regulate Behavioral Visual Acuity in Rats. Invest Ophthalmol Vis Sci 2021; 62:20. [PMID: 34137807 PMCID: PMC8212442 DOI: 10.1167/iovs.62.7.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 05/15/2021] [Indexed: 11/24/2022] Open
Abstract
Purpose Synaptosomal actin dynamics are essential for synaptic structural stability. Whether actin dynamics are involved in structural and functional synaptic plasticity within the primary visual cortex (V1) or behavioral visual acuity in rats has still not been thoroughly investigated. Methods Synaptosome preparation and western blot analysis were used to analyze synaptosomal actin dynamics. Transmission electron microscopy was used to detect synaptic density and mitochondrial area alterations. A visual water maze task was applied to assess behavioral visual acuity. Microinjection of the actin polymerization inhibitor or stabilizer detected the effect of actin dynamics on visual function. Results Actin dynamics, the mitochondrial area, and synaptic density within the area of V1 are increased during the critical period for the development of binocularity. Microinjection of the actin polymerization inhibitor cytochalasin D into the V1 decreased the mitochondrial area, synaptic density, and behavioral visual acuity. Long-term monocular deprivation reduced actin dynamics, the mitochondrial area, and synaptic density within the V1 contralateral to the deprived eye compared with those ipsilateral to the deprived eye and impaired visual acuity in the amblyopic eye. In addition, the mitochondrial area, synaptic density, and behavioral visual acuity were improved by stabilization of actin polymerization by jasplakinolide microinjection. Conclusions During the critical period of visual development of binocularity, synaptosomal actin dynamics regulate synaptic structure and function and play roles in behavioral visual acuity in rats.
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Affiliation(s)
- Ai-Ling Bi
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Eye Institute of the Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Yue-Ying Zhang
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- School of Basic Medical Sciences, Shandong First Medical University, Jinan, Shandong Province, China
| | - Zhi-Yuan Lu
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Hong-Ying Tang
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Xiu-Yan Zhang
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Zi-Han Zhang
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Bo-Qin Li
- Ultrastructural Laboratory, Shandong WEI-YA Biotech Company, Jinan, Shandong Province, China
| | - Da-Dong Guo
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Eye Institute of the Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Sheng Gong
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Qian Li
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Xing-Rong Wang
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Xiu-Zhen Lu
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Hong-Sheng Bi
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, Jinan, Shandong Province, China
- Eye Institute of the Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
- Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
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12
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Kasamatsu T, Imamura K. Ocular dominance plasticity: Molecular mechanisms revisited. J Comp Neurol 2020; 528:3039-3074. [PMID: 32737874 DOI: 10.1002/cne.25001] [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: 07/10/2020] [Accepted: 07/10/2020] [Indexed: 12/14/2022]
Abstract
Ocular dominance plasticity (ODP) is a type of cortical plasticity operating in visual cortex of mammals that are endowed with binocular vision based on the competition-driven disparity. Earlier, a molecular mechanism was proposed that catecholamines play an important role in the maintenance of ODP in kittens. Having survived the initial test, the hypothesis was further advanced to identify noradrenaline (NA) as a key factor that regulates ODP in the immature cortex. Later, the ODP-promoting effect of NA is extended to the adult with age-related limitations. Following the enhanced NA availability, the chain events downstream lead to the β-adrenoreceptor-induced cAMP accumulation, which in turn activates the protein kinase A. Eventually, the protein kinase translocates to the cell nucleus to activate cAMP responsive element binding protein (CREB). CREB is a cellular transcription factor that controls the transcription of various genes, underpinning neuronal plasticity and long-term memory. In the advent of molecular genetics in that various types of new tools have become available with relative ease, ODP research has lightly adopted in the rodent model the original concepts and methodologies. Here, after briefly tracing the strategic maturation of our quest, the review moves to the later development of the field, with the emphasis placed around the following issues: (a) Are we testing ODP per se? (b) What does monocular deprivation deprive of the immature cortex? (c) The critical importance of binocular competition, (d) What is the adult plasticity? (e) Excitation-Inhibition balance in local circuits, and (f) Species differences in the animal models.
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Affiliation(s)
- Takuji Kasamatsu
- Smith-Kettlewell Eye Research Institute, San Francisco, California, USA
| | - Kazuyuki Imamura
- Department of Systems Life Engineering, Maebashi Institute of Technology, Maebashi-shi, Gunma, Japan
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13
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Frank MG. The Ontogenesis of Mammalian Sleep: Form and Function. CURRENT SLEEP MEDICINE REPORTS 2020; 6:267-279. [PMID: 33816063 PMCID: PMC8014960 DOI: 10.1007/s40675-020-00190-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE OF REVIEW To present an up-to-date review and synthesis of findings about perinatal sleep development and function. I discuss landmark events in sleep ontogenesis, evidence that sleep promotes brain development and plasticity, and experimental considerations in this topic. RECENT FINDINGS Mammalian sleep undergoes dramatic changes in expression and regulation during perinatal development. This includes a progressive decrease in rapid-eye-movement (REM) sleep time, corresponding increases in nonREM sleep and wake time, and the appearance of mature sleep regulatory processes (homeostatic and circadian). These developmental events coincide with periods of rapid brain maturation and heightened synaptic plasticity. The latter involve an initial experience-independent phase, when circuit development is guided by spontaneous activity, and later occurring critical periods, when these circuits are shaped by experience. SUMMARY These ontogenetic changes suggest important interactions between sleep and brain development. More specifically, sleep may promote developmental programs of synaptogenesis and synaptic pruning and influence the opening and closing of critical periods of brain plasticity.
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Affiliation(s)
- Marcos G Frank
- Washington State University Spokane, Elson S. Floyd College of Medicine, Pharmaceutical and Biomedical Science Building 213, 412 E. Spokane Falls Blvd
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14
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Baroncelli L, Lunghi C. Neuroplasticity of the visual cortex: in sickness and in health. Exp Neurol 2020; 335:113515. [PMID: 33132181 DOI: 10.1016/j.expneurol.2020.113515] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/14/2020] [Accepted: 10/21/2020] [Indexed: 01/18/2023]
Abstract
Brain plasticity refers to the ability of synaptic connections to adapt their function and structure in response to experience, including environmental changes, sensory deprivation and injuries. Plasticity is a distinctive, but not exclusive, property of the developing nervous system. This review introduces the concept of neuroplasticity and describes classic paradigms to illustrate cellular and molecular mechanisms underlying synapse modifiability. Then, we summarize a growing number of studies showing that the adult cerebral cortex retains a significant degree of plasticity highlighting how the identification of strategies to enhance the plastic potential of the adult brain could pave the way for the development of novel therapeutic approaches aimed at treating amblyopia and other neurodevelopmental disorders. Finally, we analyze how the visual system adjusts to neurodegenerative conditions leading to blindness and we discuss the crucial role of spared plasticity in the visual system for sight recovery.
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Affiliation(s)
- Laura Baroncelli
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy.
| | - Claudia Lunghi
- Laboratoire des systèmes perceptifs, Département d'études cognitives, École normale supérieure, PSL University, CNRS, 75005 Paris, France
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15
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Macharadze T, Budinger E, Brosch M, Scheich H, Ohl FW, Henschke JU. Early Sensory Loss Alters the Dendritic Branching and Spine Density of Supragranular Pyramidal Neurons in Rodent Primary Sensory Cortices. Front Neural Circuits 2019; 13:61. [PMID: 31611778 PMCID: PMC6773815 DOI: 10.3389/fncir.2019.00061] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 09/03/2019] [Indexed: 01/26/2023] Open
Abstract
Multisensory integration in primary auditory (A1), visual (V1), and somatosensory cortex (S1) is substantially mediated by their direct interconnections and by thalamic inputs across the sensory modalities. We have previously shown in rodents (Mongolian gerbils) that during postnatal development, the anatomical and functional strengths of these crossmodal and also of sensory matched connections are determined by early auditory, somatosensory, and visual experience. Because supragranular layer III pyramidal neurons are major targets of corticocortical and thalamocortical connections, we investigated in this follow-up study how the loss of early sensory experience changes their dendritic morphology. Gerbils were sensory deprived early in development by either bilateral sciatic nerve transection at postnatal day (P) 5, ototoxic inner hair cell damage at P10, or eye enucleation at P10. Sholl and branch order analyses of Golgi-stained layer III pyramidal neurons at P28, which demarcates the end of the sensory critical period in this species, revealed that visual and somatosensory deprivation leads to a general increase of apical and basal dendritic branching in A1, V1, and S1. In contrast, dendritic branching, particularly of apical dendrites, decreased in all three areas following auditory deprivation. Generally, the number of spines, and consequently spine density, along the apical and basal dendrites decreased in both sensory deprived and non-deprived cortical areas. Therefore, we conclude that the loss of early sensory experience induces a refinement of corticocortical crossmodal and other cortical and thalamic connections by pruning of dendritic spines at the end of the critical period. Based on present and previous own results and on findings from the literature, we propose a scenario for multisensory development following early sensory loss.
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Affiliation(s)
- Tamar Macharadze
- Department Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Clinic for Anesthesiology and Intensive Care Medicine, Otto von Guericke University Hospital, Magdeburg, Germany
| | - Eike Budinger
- Department Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Michael Brosch
- Center for Behavioral Brain Sciences, Magdeburg, Germany.,Special Lab Primate Neurobiology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Henning Scheich
- Center for Behavioral Brain Sciences, Magdeburg, Germany.,Emeritus Group Lifelong Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Frank W Ohl
- Department Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany.,Institute for Biology, Otto von Guericke University, Magdeburg, Germany
| | - Julia U Henschke
- Institute of Cognitive Neurology and Dementia Research (IKND), Otto von Guericke University, Magdeburg, Germany
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16
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Abstract
Rett syndrome (RTT) is a severe neurological disorder caused by mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). Almost two decades of research into RTT have greatly advanced our understanding of the function and regulation of the multifunctional protein MeCP2. Here, we review recent advances in understanding how loss of MeCP2 impacts different stages of brain development, discuss recent findings demonstrating the molecular role of MeCP2 as a transcriptional repressor, assess primary and secondary effects of MeCP2 loss and examine how loss of MeCP2 can result in an imbalance of neuronal excitation and inhibition at the circuit level along with dysregulation of activity-dependent mechanisms. These factors present challenges to the search for mechanism-based therapeutics for RTT and suggest specific approaches that may be more effective than others.
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17
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Abstract
A key step in excitatory synapse maturation is the switch in AMPA receptor subunit composition to GluA2-containing calcium-impermeable receptors. Now, Blanco-Suarez et al. (2018) demonstrate that astrocyte-secreted chordin-like 1 drives this process, enabling synapse maturation and limiting plasticity.
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Affiliation(s)
- Katherine T Baldwin
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Cagla Eroglu
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA; Duke Institute for Brain Sciences (DIBS), Durham, NC 27710, USA.
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18
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Grieco SF, Holmes TC, Xu X. Neuregulin directed molecular mechanisms of visual cortical plasticity. J Comp Neurol 2019; 527:668-678. [PMID: 29464684 PMCID: PMC6103898 DOI: 10.1002/cne.24414] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 02/06/2023]
Abstract
Experience-dependent critical period (CP) plasticity has been extensively studied in the visual cortex. Monocular deprivation during the CP affects ocular dominance, limits visual performance, and contributes to the pathological etiology of amblyopia. Neuregulin-1 (NRG1) signaling through its tyrosine kinase receptor ErbB4 is essential for the normal development of the nervous system and has been linked to neuropsychiatric disorders such as schizophrenia. We discovered recently that NRG1/ErbB4 signaling in PV neurons is critical for the initiation of CP visual cortical plasticity by controlling excitatory synaptic inputs onto PV neurons and thus PV-cell mediated cortical inhibition that occurs following visual deprivation. Building on this discovery, we review the existing literature of neuregulin signaling in developing and adult cortex and address the implication of NRG/ErbB4 signaling in visual cortical plasticity at the cellular and circuit levels. NRG-directed research may lead to therapeutic approaches to reactivate plasticity in the adult cortex.
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Affiliation(s)
- Steven F Grieco
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
- Department of Biomedical Engineering, University of California, Irvine, California
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California
| | - Todd C Holmes
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
- Department of Biomedical Engineering, University of California, Irvine, California
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
- Department of Biomedical Engineering, University of California, Irvine, California
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California
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19
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Abstract
Sleep is a highly conserved phenomenon in endotherms, and therefore it must serve at least one basic function across this wide range of species. What that function is remains one of the biggest mysteries in neurobiology. By using the word neurobiology, we do not mean to exclude possible non-neural functions of sleep, but it is difficult to imagine why the brain must be taken offline if the basic function of sleep did not involve the nervous system. In this chapter we discuss several current hypotheses about sleep function. We divide these hypotheses into two categories: ones that propose higher-order cognitive functions and ones that focus on housekeeping or restorative processes. We also pose four aspects of sleep that any successful functional hypothesis has to account for: why do the properties of sleep change across the life span? Why and how is sleep homeostatically regulated? Why must the brain be taken offline to accomplish the proposed function? And, why are there two radically different stages of sleep?The higher-order cognitive function hypotheses we discuss are essential mechanisms of learning and memory and synaptic plasticity. These are not mutually exclusive hypotheses. Each focuses on specific mechanistic aspects of sleep, and higher-order cognitive processes are likely to involve components of all of these mechanisms. The restorative hypotheses are maintenance of brain energy metabolism, macromolecular biosynthesis, and removal of metabolic waste. Although these three hypotheses seem more different than those related to higher cognitive function, they may each contribute important components to a basic sleep function. Any sleep function will involve specific gene expression and macromolecular biosynthesis, and as we explain there may be important connections between brain energy metabolism and the need to remove metabolic wastes.A deeper understanding of sleep functions in endotherms will enable us to answer whether or not rest behaviors in species other than endotherms are homologous with mammalian and avian sleep. Currently comparisons across the animal kingdom depend on superficial and phenomenological features of rest states and sleep, but investigations of sleep functions would provide more insight into the evolutionary relationships between EEG-defined sleep in endotherms and rest states in ectotherms.
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Affiliation(s)
- Marcos G Frank
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University Spokane, Spokane, WA, USA
| | - H Craig Heller
- Department of Biology, Stanford University, Stanford, CA, USA.
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20
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Huda R, Goard MJ, Pho GN, Sur M. Neural mechanisms of sensorimotor transformation and action selection. Eur J Neurosci 2018; 49:1055-1060. [PMID: 30019473 DOI: 10.1111/ejn.14069] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/22/2018] [Accepted: 07/02/2018] [Indexed: 12/25/2022]
Abstract
Ray Guillery made major contributions to our understanding of the development and function of the brain. One of his principal conceptual insights, developed together with Murray Sherman [S.M. Sherman & R.W. Guillery (2001) Exploring the Thalamus. Elsevier, Amstrerdam; S. Sherman & R. Guillery (2006) Exploring the Thalamus and Its Role in Cortical Functioning. Academic Press, New York, NY; S.M. Sherman & R.W. Guillery (2013) Functional Connections of Cortical Areas: A New View from the Thalamus. MIT Press, Cambridge, MA and then in his last book (R. Guillery (2017) The Brain as a Tool: A Neuroscientist's Account. Oxford University Press, Oxford, UK)], was that the brain is a 'tool' to understand the world. In this view, the brain does not passively process sensory information and use the result to inform motor outputs. Rather, sensory and motor signals are widely broadcast and inextricably linked, with ongoing sensorimotor transformations serving as the basis for interaction with the outside world. Here, we describe recent studies from our laboratory and others which demonstrate this astute framing of the link among sensation, perception, and action postulated by Guillery and others [G. Deco & E.T. Rolls (2005) Prog Neurobiol, 76, 236-256; P. Cisek & J.F. Kalaska (2010) Annu Rev Neurosci, 33, 269-298]. Guillery situated his understanding in the deeply intertwined relationship between the thalamus and cortex, and importantly in the feedback from cortex to thalamus which in turn influences feed-forward drive to cortex [S.M. Sherman & R.W. Guillery (2001) Exploring the Thalamus. Elsevier, Amstrerdam; S. Sherman & R. Guillery (2006) Exploring the Thalamus and Its Role in Cortical Functioning. Academic Press, New York, NY]. We extend these observations to argue that brain mechanisms for sensorimotor transformations involve cortical and subcortical circuits that create internal models as a substrate for action, that a key role of sensory inputs is to update such models, and that a major function of sensorimotor processing underlying cognition is to enable action selection and execution.
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Affiliation(s)
- Rafiq Huda
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Michael J Goard
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA.,Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Gerald N Pho
- Department of Organismic and Evolutionary Biology, Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Mriganka Sur
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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21
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Renouard L, Bridi MCD, Coleman T, Arckens L, Frank MG. Anatomical correlates of rapid eye movement sleep-dependent plasticity in the developing cortex. Sleep 2018; 41:5042994. [PMID: 31796959 DOI: 10.1093/sleep/zsy124] [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: 03/06/2018] [Revised: 05/10/2018] [Indexed: 11/13/2022] Open
Abstract
Rapid eye movement (REM) sleep is expressed at its highest levels during early life when the brain is rapidly developing. This suggests that REM sleep may play important roles in brain maturation and developmental plasticity. We investigated this possibility by examining the role of REM sleep in the regulation of plasticity-related proteins known to govern synaptic plasticity in vitro and in vivo. We combined immunohistochemistry with a classic model of experience-dependent plasticity in the developing brain known to be consolidated during sleep. We found that after the developing visual cortex is triggered to remodel, it is reactivated during REM sleep (as measured by FOS+ and ARC+ cells). This is accompanied by expression of several proteins implicated in synaptic long-term potentiation (PSD95 and phosphorylated (p), mTOR, cofilin, and CREB) across the different cortical layers. These changes did not occur in animals deprived of REM sleep, but were preserved in control animals that were instead awakened in non- (N) REM sleep. Collectively, these findings support a role for REM sleep in developmental brain plasticity.
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Affiliation(s)
- Leslie Renouard
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA
| | - Michelle C D Bridi
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD
| | - Tammi Coleman
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | | | - Marcos G Frank
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA
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22
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Kole K, Komuro Y, Provaznik J, Pistolic J, Benes V, Tiesinga P, Celikel T. Transcriptional mapping of the primary somatosensory cortex upon sensory deprivation. Gigascience 2018; 6:1-6. [PMID: 29020745 PMCID: PMC5965344 DOI: 10.1093/gigascience/gix081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 08/16/2017] [Indexed: 12/03/2022] Open
Abstract
Experience-dependent plasticity (EDP) is essential for anatomical and functional
maturation of sensory circuits during development. Although the principal synaptic and
circuit mechanisms of EDP are increasingly well studied experimentally and
computationally, its molecular mechanisms remain largely elusive. EDP can be readily
studied in the rodent barrel cortex, where each “barrel column” preferentially represents
deflections of its own principal whisker. Depriving select whiskers while sparing their
neighbours introduces competition between barrel columns, ultimately leading to weakening
of intracortical, translaminar (i.e., cortical layer (L)4-to-L2/3) feed-forward excitatory
projections in the deprived columns. The same synapses are potentiated in the neighbouring
spared columns. These experience-dependent alterations of synaptic strength are thought to
underlie somatosensory map plasticity. We used RNA sequencing in this model system to
uncover cortical-column and -layer specific changes on the transcriptome level that are
induced by altered sensory experience. Column- and layer-specific barrel cortical tissues
were collected from juvenile mice with all whiskers intact and mice that received 11–12
days of long whisker (C-row) deprivation before high-quality RNA was purified and
sequenced. The current dataset entails an average of 50 million paired-end reads per
sample, 75 base pairs in length. On average, 90.15% of reads could be uniquely mapped to
the mm10 reference mouse genome. The current data reveal the transcriptional changes in
gene expression in the barrel cortex upon altered sensory experience in juvenile mice and
will help to molecularly map the mechanisms of cortical plasticity.
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Affiliation(s)
- Koen Kole
- Department of Neurophysiology, Heyendaalseweg 135, 6525 HJ Nijmegen, the Netherlands.,Department of Neuroinformatics, Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Heyendaalseweg 135, 6525 HJ Nijmegen, the Netherlands
| | - Yutaro Komuro
- Department of Neurophysiology, Heyendaalseweg 135, 6525 HJ Nijmegen, the Netherlands
| | - Jan Provaznik
- European Molecular Biology Laboratory (EMBL), Genomics Core Facility, Meyerhofstr. 1, D-69117 Heidelberg, Germany
| | - Jelena Pistolic
- European Molecular Biology Laboratory (EMBL), Genomics Core Facility, Meyerhofstr. 1, D-69117 Heidelberg, Germany
| | - Vladimir Benes
- European Molecular Biology Laboratory (EMBL), Genomics Core Facility, Meyerhofstr. 1, D-69117 Heidelberg, Germany
| | - Paul Tiesinga
- Department of Neuroinformatics, Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Heyendaalseweg 135, 6525 HJ Nijmegen, the Netherlands
| | - Tansu Celikel
- Department of Neurophysiology, Heyendaalseweg 135, 6525 HJ Nijmegen, the Netherlands
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23
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Henschke JU, Oelschlegel AM, Angenstein F, Ohl FW, Goldschmidt J, Kanold PO, Budinger E. Early sensory experience influences the development of multisensory thalamocortical and intracortical connections of primary sensory cortices. Brain Struct Funct 2018; 223:1165-1190. [PMID: 29094306 PMCID: PMC5871574 DOI: 10.1007/s00429-017-1549-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 09/29/2017] [Indexed: 12/21/2022]
Abstract
The nervous system integrates information from multiple senses. This multisensory integration already occurs in primary sensory cortices via direct thalamocortical and corticocortical connections across modalities. In humans, sensory loss from birth results in functional recruitment of the deprived cortical territory by the spared senses but the underlying circuit changes are not well known. Using tracer injections into primary auditory, somatosensory, and visual cortex within the first postnatal month of life in a rodent model (Mongolian gerbil) we show that multisensory thalamocortical connections emerge before corticocortical connections but mostly disappear during development. Early auditory, somatosensory, or visual deprivation increases multisensory connections via axonal reorganization processes mediated by non-lemniscal thalamic nuclei and the primary areas themselves. Functional single-photon emission computed tomography of regional cerebral blood flow reveals altered stimulus-induced activity and higher functional connectivity specifically between primary areas in deprived animals. Together, we show that intracortical multisensory connections are formed as a consequence of sensory-driven multisensory thalamocortical activity and that spared senses functionally recruit deprived cortical areas by an altered development of sensory thalamocortical and corticocortical connections. The functional-anatomical changes after early sensory deprivation have translational implications for the therapy of developmental hearing loss, blindness, and sensory paralysis and might also underlie developmental synesthesia.
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Affiliation(s)
- Julia U Henschke
- Department Systems Physiology of Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- German Center for Neurodegenerative Diseases Within the Helmholtz Association, Leipziger Str. 44, 39120, Magdeburg, Germany
- Institute of Cognitive Neurology and Dementia Research (IKND), Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Universitätsplatz 2, 39120, Magdeburg, Germany
| | - Anja M Oelschlegel
- Research Group Neuropharmacology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Institute of Anatomy, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany
| | - Frank Angenstein
- Functional Neuroimaging Group, German Center for Neurodegenerative Diseases Within the Helmholtz Association, Leipziger Str. 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Universitätsplatz 2, 39120, Magdeburg, Germany
| | - Frank W Ohl
- Department Systems Physiology of Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Institute of Biology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Universitätsplatz 2, 39120, Magdeburg, Germany
| | - Jürgen Goldschmidt
- Department Systems Physiology of Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Universitätsplatz 2, 39120, Magdeburg, Germany
| | - Patrick O Kanold
- Department of Biology, University of Maryland, College Park, MD, 20742, USA
| | - Eike Budinger
- Department Systems Physiology of Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany.
- Center for Behavioral Brain Sciences, Universitätsplatz 2, 39120, Magdeburg, Germany.
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Major Vault Protein, a Candidate Gene in 16p11.2 Microdeletion Syndrome, Is Required for the Homeostatic Regulation of Visual Cortical Plasticity. J Neurosci 2018. [PMID: 29540554 DOI: 10.1523/jneurosci.2034-17.2018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Microdeletion of a region in chromosome 16p11.2 increases susceptibility to autism. Although this region contains exons of 29 genes, disrupting only a small segment of the region, which spans five genes, is sufficient to cause autistic traits. One candidate gene in this critical segment is MVP, which encodes for the major vault protein (MVP) that has been implicated in regulation of cellular transport mechanisms. MVP expression levels in MVP+/- mice closely phenocopy those of 16p11.2 mutant mice, suggesting that MVP+/- mice may serve as a model of MVP function in 16p11.2 microdeletion. Here we show that MVP regulates the homeostatic component of ocular dominance (OD) plasticity in primary visual cortex. MVP+/- mice of both sexes show impairment in strengthening of open-eye responses after several days of monocular deprivation (MD), whereas closed-eye responses are weakened as normal, resulting in reduced overall OD plasticity. The frequency of miniature EPSCs (mEPSCs) in pyramidal neurons is decreased in MVP+/- mice after extended MD, suggesting a reduction of functional synapses. Correspondingly, upregulation of surface GluA1 AMPA receptors is reduced in MVP+/- mice after extended MD, and is accompanied by altered expression of STAT1 and phosphorylated ERK, which have been previously implicated in OD plasticity. Normalization of STAT1 levels by introducing STAT1 shRNA rescues surface GluA1 and open-eye responses, implicating STAT1 as a downstream effector of MVP. These findings demonstrate a specific role for MVP as a key molecule influencing the homeostatic component of activity-dependent synaptic plasticity, and potentially the corresponding phenotypes of 16p11.2 microdeletion syndrome.SIGNIFICANCE STATEMENT Major vault protein (MVP), a candidate gene in 16p11.2 microdeletion syndrome, has been implicated in the regulation of several cellular processes including transport mechanisms and scaffold signaling. However, its role in brain function and plasticity remains unknown. In this study, we identified MVP as an important regulator of the homeostatic component of experience-dependent plasticity, via regulation of STAT1 and ERK signaling. This study helps reveal a new mechanism for an autism-related gene in brain function, and suggests a broader role for neuro-immune interactions in circuit level plasticity. Importantly, our findings might explain specific components of the pathophysiology of 16p11.2 microdeletion syndrome.
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Fernández-Montoya J, Avendaño C, Negredo P. The Glutamatergic System in Primary Somatosensory Neurons and Its Involvement in Sensory Input-Dependent Plasticity. Int J Mol Sci 2017; 19:ijms19010069. [PMID: 29280965 PMCID: PMC5796019 DOI: 10.3390/ijms19010069] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/19/2017] [Accepted: 12/21/2017] [Indexed: 01/25/2023] Open
Abstract
Glutamate is the most common neurotransmitter in both the central and the peripheral nervous system. Glutamate is present in all types of neurons in sensory ganglia, and is released not only from their peripheral and central axon terminals but also from their cell bodies. Consistently, these neurons express ionotropic and metabotropic receptors, as well as other molecules involved in the synthesis, transport and release of the neurotransmitter. Primary sensory neurons are the first neurons in the sensory channels, which receive information from the periphery, and are thus key players in the sensory transduction and in the transmission of this information to higher centers in the pathway. These neurons are tightly enclosed by satellite glial cells, which also express several ionotropic and metabotropic glutamate receptors, and display increases in intracellular calcium accompanying the release of glutamate. One of the main interests in our group has been the study of the implication of the peripheral nervous system in sensory-dependent plasticity. Recently, we have provided novel evidence in favor of morphological changes in first- and second-order neurons of the trigeminal system after sustained alterations of the sensory input. Moreover, these anatomical changes are paralleled by several molecular changes, among which those related to glutamatergic neurotransmission are particularly relevant. In this review, we will describe the state of the art of the glutamatergic system in sensory ganglia and its involvement in input-dependent plasticity, a fundamental ground for advancing our knowledge of the neural mechanisms of learning and adaptation, reaction to injury, and chronic pain.
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Affiliation(s)
- Julia Fernández-Montoya
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, 28029 Madrid, Spain.
| | - Carlos Avendaño
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, 28029 Madrid, Spain.
| | - Pilar Negredo
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, 28029 Madrid, Spain.
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26
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Lowery RL, Tremblay ME, Hopkins BE, Majewska AK. The microglial fractalkine receptor is not required for activity-dependent plasticity in the mouse visual system. Glia 2017; 65:1744-1761. [PMID: 28836393 DOI: 10.1002/glia.23192] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 04/27/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022]
Abstract
Microglia have recently been implicated as key regulators of activity-dependent plasticity, where they contribute to the removal of inappropriate or excess synapses. However, the molecular mechanisms that mediate this microglial function are still not well understood. Although multiple studies have implicated fractalkine signaling as a mediator of microglia-neuron communications during synaptic plasticity, it is unclear whether this is a universal signaling mechanism or whether its role is limited to specific brain regions and stages of the lifespan. Here, we examined whether fractalkine signaling mediates microglial contributions to activity-dependent plasticity in the developing and adolescent visual system. Using genetic ablation of fractalkine's cognate receptor, CX3 CR1, and both ex vivo characterization and in vivo imaging in mice, we examined whether fractalkine signaling is required for microglial dynamics and modulation of synapses, as well as activity-dependent plasticity in the visual system. We did not find a role for fractalkine signaling in mediating microglial properties during visual plasticity. Ablation of CX3 CR1 had no effect on microglial density, distribution, morphology, or motility, in either adolescent or young adult mice across brain regions that include the visual cortex. Ablation of CX3 CR1 also had no effect on baseline synaptic turnover or contact dynamics between microglia and neurons. Finally, we found that fractalkine signaling is not required for either early or late forms of activity-dependent visual system plasticity. These findings suggest that fractalkine is not a universal regulator of synaptic plasticity, but rather has heterogeneous roles in specific brain regions and life stages.
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Affiliation(s)
- Rebecca L Lowery
- Neuroscience Graduate Program, University of Rochester, Rochester, New York, 14642.,Department of Neuroscience, Center for Visual Science, University of Rochester, Rochester, New York, 14642
| | - Marie-Eve Tremblay
- Department of Neuroscience, Center for Visual Science, University of Rochester, Rochester, New York, 14642.,Department of Molecular Medicine, Université Laval, and Axe Neurosciences, Centre De Recherche Du CHU De Québec, Québec City, Canada
| | - Brittany E Hopkins
- Department of Neuroscience, Center for Visual Science, University of Rochester, Rochester, New York, 14642
| | - Ania K Majewska
- Department of Neuroscience, Center for Visual Science, University of Rochester, Rochester, New York, 14642
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27
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Hsu A, Luebke JI, Medalla M. Comparative ultrastructural features of excitatory synapses in the visual and frontal cortices of the adult mouse and monkey. J Comp Neurol 2017; 525:2175-2191. [PMID: 28256708 DOI: 10.1002/cne.24196] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 01/18/2017] [Accepted: 02/10/2017] [Indexed: 01/20/2023]
Abstract
The excitatory glutamatergic synapse is the principal site of communication between cortical pyramidal neurons and their targets, a key locus of action of many drugs, and highly vulnerable to dysfunction and loss in neurodegenerative disease. A detailed knowledge of the structure of these synapses in distinct cortical areas and across species is a prerequisite for understanding the anatomical underpinnings of cortical specialization and, potentially, selective vulnerability in neurological disorders. We used serial electron microscopy to assess the ultrastructural features of excitatory (asymmetric) synapses in the layers 2-3 (L2-3) neuropil of visual (V1) and frontal (FC) cortices of the adult mouse and compared findings to those in the rhesus monkey (V1 and lateral prefrontal cortex [LPFC]). Analyses of multiple ultrastructural variables revealed four organizational features. First, the density of asymmetric synapses does not differ between frontal and visual cortices in either species, but is significantly higher in mouse than in monkey. Second, the structural properties of asymmetric synapses in mouse V1 and FC are nearly identical, by stark contrast to the significant differences seen between monkey V1 and LPFC. Third, while the structural features of postsynaptic entities in mouse and monkey V1 do not differ, the size of presynaptic boutons are significantly larger in monkey V1. Fourth, both presynaptic and postsynaptic entities are significantly smaller in the mouse FC than in the monkey LPFC. The diversity of synaptic ultrastructural features demonstrated here have broad implications for the nature and efficacy of glutamatergic signaling in distinct cortical areas within and across species.
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Affiliation(s)
- Alexander Hsu
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts
| | - Jennifer I Luebke
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts
| | - Maria Medalla
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts
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28
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Wijtenburg SA, West J, Korenic SA, Kuhney F, Gaston FE, Chen H, Roberts M, Kochunov P, Hong LE, Rowland LM. Glutamatergic metabolites are associated with visual plasticity in humans. Neurosci Lett 2017; 644:30-36. [PMID: 28189743 DOI: 10.1016/j.neulet.2017.02.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 02/01/2017] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
Abstract
Long-term potentiation (LTP) is a basic cellular mechanism underlying learning and memory. LTP-like plasticity in the visual cortex can be induced by high frequency visual stimulation in rodents and humans. Since glutamate plays a fundamental role in LTP, this study investigated if visual cortical glutamate and glutamine levels, measured by proton magnetic resonance spectroscopy (MRS), relate to visual plasticity in humans. Since plasticity requires a delicate excitation and inhibition balance, GABA was also explored. Eighteen healthy participants completed MRS and a visual fMRI paradigm. Results revealed enhanced fMRI activations after high frequency visual stimulation, suggesting visual plasticity occurred. Higher activations were associated with higher resting glutamine levels after family wise error-correction. Exploratory analyses revealed that higher resting glutamate and GABA levels were associated with visual plasticity, suggesting there may be a critical excitation-inhibition balance necessary for experience dependent plasticity. This is the first empirical evidence that resting glutamine levels and potentially glutamate and GABA levels are associated with visual plasticity in humans.
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Affiliation(s)
- S Andrea Wijtenburg
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA.
| | - Jeffrey West
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA
| | - Stephanie A Korenic
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA
| | - Franchesca Kuhney
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA
| | - Frank E Gaston
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA
| | - Hongji Chen
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA
| | - Meredith Roberts
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA
| | - Peter Kochunov
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA; Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - L Elliot Hong
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA
| | - Laura M Rowland
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA; Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, 601 N. Caroline Street, Baltimore, MD 21287, USA; Department of Psychology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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29
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Baroncelli L, Cenni MC, Melani R, Deidda G, Landi S, Narducci R, Cancedda L, Maffei L, Berardi N. Early IGF-1 primes visual cortex maturation and accelerates developmental switch between NKCC1 and KCC2 chloride transporters in enriched animals. Neuropharmacology 2017; 113:167-177. [PMID: 26924708 DOI: 10.1016/j.neuropharm.2016.02.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 02/01/2016] [Accepted: 02/24/2016] [Indexed: 12/17/2022]
Abstract
Environmental enrichment (EE) has a remarkable impact on brain development. Continuous exposure to EE from birth determines a significant acceleration of visual system maturation both at retinal and cortical levels. A pre-weaning enriched experience is sufficient to trigger the accelerated maturation of the visual system, suggesting that factors affected by EE during the first days of life might prime visual circuits towards a faster development. The search for such factors is crucial not only to gain a better understanding of the molecular hierarchy of brain development but also to identify molecular pathways amenable to be targeted to correct atypical brain developmental trajectories. Here, we showed that IGF-1 levels are increased in the visual cortex of EE rats as early as P6 and this is a crucial event for setting in motion the developmental program induced by EE. Early intracerebroventricular (i.c.v.) infusion of IGF-1 in standard rats was sufficient to mimic the action of EE on visual acuity development, whereas blocking IGF-1 signaling by i.c.v. injections of the IGF-1 receptor antagonist JB1 prevented the deployment of EE effects. Early IGF-1 decreased the ratio between the expression of NKCC1 and KCC2 cation/chloride transporters, and the reversal potential for GABAAR-driven Cl- currents (ECl) was shifted toward more negative potentials, indicating that IGF-1 is a crucial factor in accelerating the maturation of GABAergic neurotransmission and promoting the developmental switch of GABA polarity from excitation to inhibition. In addition, early IGF-1 promoted a later occurring increase in its own expression, suggesting a priming effect of early IGF-1 in driving post-weaning cortical maturation.
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Affiliation(s)
- Laura Baroncelli
- Institute of Neuroscience CNR, via Moruzzi 1, I-56124, Pisa, Italy.
| | | | - Riccardo Melani
- Institute of Neuroscience CNR, via Moruzzi 1, I-56124, Pisa, Italy; Department of Neuroscience, Psychology, Drug Research, Child Health (NEUROFARBA), University of Florence, Piazza San Marco 4, I-50121, Florence, Italy
| | - Gabriele Deidda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, I-16163, Genoa, Italy
| | - Silvia Landi
- Institute of Neuroscience CNR, via Moruzzi 1, I-56124, Pisa, Italy
| | - Roberta Narducci
- Department of Neuroscience, Psychology, Drug Research, Child Health (NEUROFARBA), University of Florence, Piazza San Marco 4, I-50121, Florence, Italy
| | - Laura Cancedda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, I-16163, Genoa, Italy
| | - Lamberto Maffei
- Institute of Neuroscience CNR, via Moruzzi 1, I-56124, Pisa, Italy; Laboratory of Neurobiology, Scuola Normale Superiore, Piazza Cavalieri 7, I-56126, Pisa, Italy
| | - Nicoletta Berardi
- Institute of Neuroscience CNR, via Moruzzi 1, I-56124, Pisa, Italy; Department of Neuroscience, Psychology, Drug Research, Child Health (NEUROFARBA), University of Florence, Piazza San Marco 4, I-50121, Florence, Italy
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30
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Combes RD, Shah AB. The use of in vivo, ex vivo, in vitro, computational models and volunteer studies in vision research and therapy, and their contribution to the Three Rs. Altern Lab Anim 2017; 44:187-238. [PMID: 27494623 DOI: 10.1177/026119291604400302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Much is known about mammalian vision, and considerable progress has been achieved in treating many vision disorders, especially those due to changes in the eye, by using various therapeutic methods, including stem cell and gene therapy. While cells and tissues from the main parts of the eye and the visual cortex (VC) can be maintained in culture, and many computer models exist, the current non-animal approaches are severely limiting in the study of visual perception and retinotopic imaging. Some of the early studies with cats and non-human primates (NHPs) are controversial for animal welfare reasons and are of questionable clinical relevance, particularly with respect to the treatment of amblyopia. More recently, the UK Home Office records have shown that attention is now more focused on rodents, especially the mouse. This is likely to be due to the perceived need for genetically-altered animals, rather than to knowledge of the similarities and differences of vision in cats, NHPs and rodents, and the fact that the same techniques can be used for all of the species. We discuss the advantages and limitations of animal and non-animal methods for vision research, and assess their relative contributions to basic knowledge and clinical practice, as well as outlining the opportunities they offer for implementing the principles of the Three Rs (Replacement, Reduction and Refinement).
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Affiliation(s)
| | - Atul B Shah
- Ophthalmic Surgeon, National Eye Registry Ltd, Leicester, UK
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31
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Stiles J. Principles of brain development. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2017; 8:10.1002/wcs.1402. [PMID: 27906509 PMCID: PMC5182160 DOI: 10.1002/wcs.1402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 05/29/2016] [Indexed: 11/05/2022]
Abstract
Throughout much of the 20th century, the major models of brain development were strongly deterministic. It was thought that brain development proceeds via a prescribed blueprint that is somehow innately specified in the organism. Contemporary models present a distinctly different view of both inheritance and brain development. First, we do not inherit blueprints or plans, we inherit genes and the cellular machinery for expressing them. Genes carry essential information for creating proteins, but do not determine biological processes or developmental outcomes; the first cells contain the elements necessary for creating proteins based on the information coded in the nucleotide sequences of genes. Second, brain development is dynamic: the biological state of the brain at any moment is the product of developmental processes that involve an intricate interplay among genes and an ever-expanding range of environmental factors-from local cellular events to influences from the outside world. In science, models matter. They reflect underlying assumptions about how things can happen, and thus influence the kinds of questions we ask, the kinds of experiments we propose, the therapies we develop, and the educational curricula we construct. The dynamic model of brain development accounts for powerful neurobehavioral effects that can simply not be accommodated by deterministic models. WIREs Cogn Sci 2017, 8:e1402. doi: 10.1002/wcs.1402 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Joan Stiles
- Department of Cognitive Science, University of California, San Diego, CA, USA
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32
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Broad KD, Hassell J, Fleiss B, Kawano G, Ezzati M, Rocha-Ferreira E, Hristova M, Bennett K, Fierens I, Burnett R, Chaban B, Alonso-Alconada D, Oliver-Taylor A, Tachsidis I, Rostami J, Gressens P, Sanders RD, Robertson NJ. Isoflurane Exposure Induces Cell Death, Microglial Activation and Modifies the Expression of Genes Supporting Neurodevelopment and Cognitive Function in the Male Newborn Piglet Brain. PLoS One 2016; 11:e0166784. [PMID: 27898690 PMCID: PMC5127656 DOI: 10.1371/journal.pone.0166784] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/03/2016] [Indexed: 12/02/2022] Open
Abstract
Exposure of the brain to general anesthesia during early infancy may adversely affect its neural and cognitive development. The mechanisms mediating this are complex, incompletely understood and may be sexually dimorphic, but include developmentally inappropriate apoptosis, inflammation and a disruption to cognitively salient gene expression. We investigated the effects of a 6h isoflurane exposure on cell death, microglial activation and gene expression in the male neonatal piglet brain. Piglets (n = 6) were randomised to: (i) naive controls or (ii) 6h isoflurane. Cell death (TUNEL and caspase-3) and microglial activation were recorded in 7 brain regions. Changes in gene expression (microarray and qPCR) were assessed in the cingulate cortex. Electroencephalography (EEG) was recorded throughout. Isoflurane anesthesia induced significant increases in cell death in the cingulate and insular cortices, caudate nucleus, thalamus, putamen, internal capsule, periventricular white matter and hippocampus. Dying cells included both neurons and oligodendrocytes. Significantly, microglial activation was observed in the insula, pyriform, hippocampus, internal capsule, caudate and thalamus. Isoflurane induced significant disruption to the expression of 79 gene transcripts, of these 26 are important for the control of transcription and 23 are important for the mediation of neural plasticity, memory formation and recall. Our observations confirm that isoflurane increases apoptosis and inflammatory responses in the neonatal piglet brain but also suggests novel additional mechanisms by which isoflurane may induce adverse neural and cognitive development by disrupting the expression of genes mediating activity dependent development of neural circuits, the predictive adaptive responses of the brain, memory formation and recall.
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Affiliation(s)
- Kevin D. Broad
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Jane Hassell
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Bobbi Fleiss
- Centre for the Developing Brain, Kings College, St Thomas’s Campus, London, United Kingdom
- Inserm, Paris, France
- University Paris Diderot, Sorbonne Paris Cite, Paris, France
| | - Go Kawano
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Mojgan Ezzati
- Institute for Women’s Health, University College London, London, United Kingdom
| | | | - Mariya Hristova
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Kate Bennett
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Igor Fierens
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Ryan Burnett
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Badr Chaban
- Institute for Women’s Health, University College London, London, United Kingdom
| | | | - Aaron Oliver-Taylor
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Ilias Tachsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Jamshid Rostami
- Institute for Women’s Health, University College London, London, United Kingdom
| | - Pierre Gressens
- Centre for the Developing Brain, Kings College, St Thomas’s Campus, London, United Kingdom
- Inserm, Paris, France
- University Paris Diderot, Sorbonne Paris Cite, Paris, France
| | - Robert D. Sanders
- Department of Anesthesiology, University of Wisconsin, Madison, United States of America
- Wellcome Department of Imaging Neuroscience, University College London, London, United Kingdom
- Surgical Outcomes Research Centre, University College London Hospital, London, United Kingdom
| | - Nicola J. Robertson
- Institute for Women’s Health, University College London, London, United Kingdom
- * E-mail:
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33
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Vierci G, Pannunzio B, Bornia N, Rossi FM. H3 and H4 Lysine Acetylation Correlates with Developmental and Experimentally Induced Adult Experience-Dependent Plasticity in the Mouse Visual Cortex. J Exp Neurosci 2016; 10:49-64. [PMID: 27891053 PMCID: PMC5117113 DOI: 10.4137/jen.s39888] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/21/2016] [Accepted: 08/27/2016] [Indexed: 12/30/2022] Open
Abstract
Histone posttranslational modifications play a fundamental role in orchestrating gene expression. In this work, we analyzed the acetylation of H3 and H4 histones (AcH3-AcH4) and its modulation by visual experience in the mouse visual cortex (VC) during normal development and in two experimental conditions that restore juvenile-like plasticity levels in adults (fluoxetine treatment and enriched environment). We found that AcH3-AcH4 declines with age and is upregulated by treatments restoring plasticity in the adult. We also found that visual experience modulates AcH3-AcH4 in young and adult plasticity-restored mice but not in untreated ones. Finally, we showed that the transporter vGAT is downregulated in adult plasticity-restored models. In summary, we identified a dynamic regulation of AcH3-AcH4, which is associated with high plasticity levels and enhanced by visual experience. These data, along with recent ones, indicate H3-H4 acetylation as a central hub in the control of experience-dependent plasticity in the VC.
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Affiliation(s)
- Gabriela Vierci
- Laboratorio de Neurociencias "Neuroplasticity Unit", Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Bruno Pannunzio
- Laboratorio de Neurociencias "Neuroplasticity Unit", Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Natalia Bornia
- Laboratorio de Neurociencias "Neuroplasticity Unit", Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Francesco M Rossi
- Laboratorio de Neurociencias "Neuroplasticity Unit", Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
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34
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Koh DXP, Sng JCG. HDAC1 negatively regulates Bdnf and Pvalb required for parvalbumin interneuron maturation in an experience-dependent manner. J Neurochem 2016; 139:369-380. [PMID: 27534825 DOI: 10.1111/jnc.13773] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 06/24/2016] [Accepted: 08/10/2016] [Indexed: 01/29/2023]
Abstract
During early postnatal development, neuronal circuits are sculpted by sensory experience provided by the external environment. This experience-dependent regulation of circuitry development consolidates the balance of excitatory-inhibitory (E/I) neurons in the brain. The cortical barrel-column that innervates a single principal whisker is used to provide a clear reference frame for studying the consolidation of E/I circuitry. Sensory deprivation of S1 at birth disrupts the consolidation of excitatory-inhibitory balance by decreasing inhibitory transmission of parvalbumin interneurons. The molecular mechanisms underlying this decrease in inhibition are not completely understood. Our findings show that epigenetic mechanisms, in particular histone deacetylation by histone deacetylases, negatively regulate the expression of brain-derived neurotrophic factor (Bdnf) and parvalbumin (Pvalb) genes during development, which are required for the maturation of parvalbumin interneurons. After whisker deprivation, increased histone deacetylase 1 expression and activity led to increased histone deacetylase 1 binding and decreased histone acetylation at Bdnf promoters I-IV and Pvalb promoter, resulting in the repression of Bdnf and Pvalb gene transcription. The decrease in Bdnf expression further affected parvalbumin interneuron maturation at layer II/III in S1, demonstrated by decreased parvalbumin expression, a marker for parvalbumin interneuron maturation. Knockdown of HDAC1 recovered Bdnf and Pvalb gene transcription and also prevented the decrease of inhibitory synapses accompanying whisker deprivation.
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Affiliation(s)
- Dawn X P Koh
- National University of Singapore, Graduate School of Integrative Sciences and Engineering, Singapore, Singapore.,Singapore Institute of Clinical Sciences (SICS), A*STAR, Brenner Centre for Molecular Medicine, Singapore, Singapore.,Department of Pharmacology, National University of Singapore, Yong Loo Lin School of Medicine, Singapore, Singapore
| | - Judy C G Sng
- Singapore Institute of Clinical Sciences (SICS), A*STAR, Brenner Centre for Molecular Medicine, Singapore, Singapore. .,Department of Pharmacology, National University of Singapore, Yong Loo Lin School of Medicine, Singapore, Singapore.
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Talaei SA, Azami A, Salami M. Developmental effect of light deprivation on synaptic plasticity of rats' hippocampus: implications for melatonin. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2016; 19:899-909. [PMID: 27746873 PMCID: PMC5048127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/28/2016] [Indexed: 11/18/2022]
Abstract
OBJECTIVES There are few reports have demonstrated the effect of a change-in-light experience on the structure and function of hippocampus. A change-in-light experience also affects the circadian pattern of melatonin secretion. This study aimed to investigate developmental effect of exogenous melatonin on synaptic plasticity of hippocampus of light deprived rats. MATERIALS AND METHODS The effects of intracerebroventricular (ICV) injection of 2μg/5μl melatonin was evaluated on the basic and tetanized field excitatory post-synaptic potentials (fEPSPs) recorded in the hippocampal CA3-CA1 pathway of normal light-reared (LR) and dark-reared (DR) rats at 2, 4, and 6 weeks of age. Using RT-PCR and western blotting, developmental changes in the expression of melatonin receptors, MT1 and MT2, in the hippocampus were also evaluated. RESULTS The amplitude of basic responses decreased across age in the LR rats. While light deprivation increased the amplitude of baseline fEPSPs, it decreased the degree of potentiation in post-tetanus responses. Melatonin injection also increased the amplitude of fEPSPs and suppressed the induction of long-term potentiation in both LR and DR rats. The expression of melatonin receptors increased in the hippocampus during brain development, and dark rearing reversed the expression patterns of both receptors. CONCLUSION Although melatonin changed basic and tetanized responses of CA1 neurons across age during critical period of brain development, the pattern of its effects did not match the expression pattern of melatonin receptors in the hippocampus. Thus, the effects of melatonin on hippocampal neuronal responses may be exerted through other ways, like intercellular molecules and nuclear hormone receptors.
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Affiliation(s)
| | - Abolfazl Azami
- Anatomical Sciences Research Center, Kashan University of Medical Sciences, Kashan, Iran
| | - Mahmoud Salami
- Physiology Research Center, Kashan University of Medical Sciences, Kashan, Iran
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Boggio E, Pancrazi L, Gennaro M, Lo Rizzo C, Mari F, Meloni I, Ariani F, Panighini A, Novelli E, Biagioni M, Strettoi E, Hayek J, Rufa A, Pizzorusso T, Renieri A, Costa M. Visual impairment in FOXG1-mutated individuals and mice. Neuroscience 2016; 324:496-508. [DOI: 10.1016/j.neuroscience.2016.03.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 03/01/2016] [Accepted: 03/08/2016] [Indexed: 01/01/2023]
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Dyer AH, Vahdatpour C, Sanfeliu A, Tropea D. The role of Insulin-Like Growth Factor 1 (IGF-1) in brain development, maturation and neuroplasticity. Neuroscience 2016; 325:89-99. [DOI: 10.1016/j.neuroscience.2016.03.056] [Citation(s) in RCA: 192] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/29/2016] [Accepted: 03/24/2016] [Indexed: 02/07/2023]
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Neuroplasticity and MRI: A perfect match. Neuroimage 2016; 131:13-28. [DOI: 10.1016/j.neuroimage.2015.08.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/03/2015] [Accepted: 08/03/2015] [Indexed: 12/21/2022] Open
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Adelson JD, Sapp RW, Brott BK, Lee H, Miyamichi K, Luo L, Cheng S, Djurisic M, Shatz CJ. Developmental Sculpting of Intracortical Circuits by MHC Class I H2-Db and H2-Kb. Cereb Cortex 2016; 26:1453-1463. [PMID: 25316337 PMCID: PMC4785944 DOI: 10.1093/cercor/bhu243] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Synapse pruning is an activity-regulated process needed for proper circuit sculpting in the developing brain. Major histocompatibility class I (MHCI) molecules are regulated by activity, but little is known about their role in the development of connectivity in cortex. Here we show that protein for 2 MHCI molecules H2-Kb and H2-Db is associated with synapses in the visual cortex. Pyramidal neurons in mice lacking H2-Kb and H2-Db (KbDb KO) have more extensive cortical connectivity than normal. Modified rabies virus tracing was used to monitor the extent of pyramidal cell connectivity: Horizontal connectivity is greater in the visual cortex of KbDb KO mice. Basal dendrites of L2/3 pyramids, where many horizontal connections terminate, are more highly branched and have elevated spine density in the KO. Furthermore, the density of axonal boutons is elevated within L2/3 of mutant mice. These increases are accompanied by elevated miniature excitatory postsynaptic current frequency, consistent with an increase in functional synapses. This functional and anatomical increase in intracortical connectivity is also associated with enhanced ocular dominance plasticity that persists into adulthood. Thus, these MHCI proteins regulate sculpting of local cortical circuits and in their absence, the excess connectivity can function as a substrate for cortical plasticity throughout life.
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Affiliation(s)
| | | | | | - Hanmi Lee
- Departments of Biology and Neurobiology and Bio-X
| | | | - Liqun Luo
- Department of Biology, Stanford University, Stanford, CA94305, USA
| | - Sarah Cheng
- Departments of Biology and Neurobiology and Bio-X
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Placental, Matrilineal, and Epigenetic Mechanisms Promoting Environmentally Adaptive Development of the Mammalian Brain. Neural Plast 2016; 2016:6827135. [PMID: 27069693 PMCID: PMC4812471 DOI: 10.1155/2016/6827135] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 03/03/2016] [Indexed: 11/17/2022] Open
Abstract
The evolution of intrauterine development, vivipary, and placentation in eutherian mammals has introduced new possibilities and constraints in the regulation of neural plasticity and development which promote neural function that is adaptive to the environment that a developing brain is likely to encounter in the future. A range of evolutionary adaptations associated with placentation transfers disproportionate control of this process to the matriline, a period unique in mammalian development in that there are three matrilineal genomes interacting in the same organism at the same time (maternal, foetal, and postmeiotic oocytes). The interactions between the maternal and developing foetal hypothalamus and placenta can provide a template by which a mother can transmit potentially adaptive information concerning potential future environmental conditions to the developing brain. In conjunction with genomic imprinting, it also provides a template to integrate epigenetic information from both maternal and paternal lineages. Placentation also hands ultimate control of genomic imprinting and intergenerational epigenetic information transfer to the matriline as epigenetic markers undergo erasure and reprogramming in the developing oocyte. These developments, in conjunction with an expanded neocortex, provide a unique evolutionary template by which matrilineal transfer of maternal care, resources, and culture can be used to promote brain development and infant survival.
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Yazar S, Hewitt AW, Forward H, Jacques A, Ing C, von Ungern-Sternberg BS, Mackey DA. Early Anesthesia Exposure and the Effect on Visual Acuity, Refractive Error, and Retinal Nerve Fiber Layer Thickness of Young Adults. J Pediatr 2016; 169:256-9.e1. [PMID: 26621047 DOI: 10.1016/j.jpeds.2015.10.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 09/01/2015] [Accepted: 10/13/2015] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To investigate whether being anesthesia administered at least once in early life influenced 3 main proxies of visual function: visual acuity, refractive error, and optic nerve health in young adulthood. STUDY DESIGN At age 20 years, participants of the Western Australian Pregnancy Cohort Study had comprehensive ocular examinations including visual acuity, postcycloplegic refraction, and multiple scans of the optic disc. We identified individuals who had at least 1 procedure requiring anesthesia during the first 3 years of life (between 1990 and 1994) and compared their visual outcomes with nonexposed individuals. We excluded 40 participants with strabismus or other ophthalmic disease or surgery and 136 with non-European background. RESULTS Of 834 participants, 15.2% (n = 127) were exposed to anesthesia at least once before age 3 years. In both exposed and nonexposed groups, median visual acuity (measured using the logarithm of the minimum angle of resolution [LogMAR] chart) was -0.06 LogMAR in the right eye and -0.08 LogMAR in the left eye (P > .05). Median spherical equivalent refractive error was +0.44 diopters (IQR -0.25, +0.63) and +0.31 diopters (IQR -0.38, +0.63) in the exposed and nonexposed group, respectively (P = .126). No difference was detected in mean global retinal nerve fiber layer thickness of the 2 groups (100.7 vs 100.1 μm, P = .830). CONCLUSIONS We were unable to demonstrate an association of exposure to anesthesia as a child with reduced visual acuity or increased myopia or thinning of retinal nerve fiber layer. These findings support the view that anesthesia is unlikely to impair visual development, but further work is needed to establish whether more subtle defects are present and repeated exposures have any effects.
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Affiliation(s)
- Seyhan Yazar
- Center for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia
| | - Alex W Hewitt
- Center for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia; Center for Eye Research Australia, The University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Hannah Forward
- Center for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia
| | - Angela Jacques
- School of Population Health, University of Western Australia, Perth, Western Australia, Australia
| | - Caleb Ing
- Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, NY
| | - Britta S von Ungern-Sternberg
- Department of Anesthesia and Pain Management, Princess Margaret Hospital for Children, Perth, Western Australia, Australia; School of Medicine and Pharmacology, The University of Western Australia, Perth, Western Australia, Australia
| | - David A Mackey
- Center for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia.
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Kelly EA, Russo AS, Jackson CD, Lamantia CE, Majewska AK. Proteolytic regulation of synaptic plasticity in the mouse primary visual cortex: analysis of matrix metalloproteinase 9 deficient mice. Front Cell Neurosci 2015; 9:369. [PMID: 26441540 PMCID: PMC4585116 DOI: 10.3389/fncel.2015.00369] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 09/04/2015] [Indexed: 01/16/2023] Open
Abstract
The extracellular matrix (ECM) is known to play important roles in regulating neuronal recovery from injury. The ECM can also impact physiological synaptic plasticity, although this process is less well understood. To understand the impact of the ECM on synaptic function and remodeling in vivo, we examined ECM composition and proteolysis in a well-established model of experience-dependent plasticity in the visual cortex. We describe a rapid change in ECM protein composition during Ocular Dominance Plasticity (ODP) in adolescent mice, and a loss of ECM remodeling in mice that lack the extracellular protease, matrix metalloproteinase-9 (MMP9). Loss of MMP9 also attenuated functional ODP following monocular deprivation (MD) and reduced excitatory synapse density and spine density in sensory cortex. While we observed no change in the morphology of existing dendritic spines, spine dynamics were altered, and MMP9 knock-out (KO) mice showed increased turnover of dendritic spines over a period of 2 days. We also analyzed the effects of MMP9 loss on microglia, as these cells are involved in extracellular remodeling and have been recently shown to be important for synaptic plasticity. MMP9 KO mice exhibited very limited changes in microglial morphology. Ultrastructural analysis, however, showed that the extracellular space surrounding microglia was increased, with concomitant increases in microglial inclusions, suggesting possible changes in microglial function in the absence of MMP9. Taken together, our results show that MMP9 contributes to ECM degradation, synaptic dynamics and sensory-evoked plasticity in the mouse visual cortex.
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Affiliation(s)
- Emily A Kelly
- Center for Visual Science, School of Medicine and Dentistry, Department of Neurobiology and Anatomy, University of Rochester Rochester, NY, USA
| | - Amanda S Russo
- Center for Visual Science, School of Medicine and Dentistry, Department of Neurobiology and Anatomy, University of Rochester Rochester, NY, USA
| | - Cory D Jackson
- Center for Visual Science, School of Medicine and Dentistry, Department of Neurobiology and Anatomy, University of Rochester Rochester, NY, USA
| | - Cassandra E Lamantia
- Center for Visual Science, School of Medicine and Dentistry, Department of Neurobiology and Anatomy, University of Rochester Rochester, NY, USA
| | - Ania K Majewska
- Center for Visual Science, School of Medicine and Dentistry, Department of Neurobiology and Anatomy, University of Rochester Rochester, NY, USA
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Dumoulin Bridi MC, Aton SJ, Seibt J, Renouard L, Coleman T, Frank MG. Rapid eye movement sleep promotes cortical plasticity in the developing brain. SCIENCE ADVANCES 2015; 1:e1500105. [PMID: 26601213 PMCID: PMC4646776 DOI: 10.1126/sciadv.1500105] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 04/28/2015] [Indexed: 05/24/2023]
Abstract
Rapid eye movement sleep is maximal during early life, but its function in the developing brain is unknown. We investigated the role of rapid eye movement sleep in a canonical model of developmental plasticity in vivo (ocular dominance plasticity in the cat) induced by monocular deprivation. Preventing rapid eye movement sleep after monocular deprivation reduced ocular dominance plasticity and inhibited activation of a kinase critical for this plasticity (extracellular signal-regulated kinase). Chronic single-neuron recording in freely behaving cats further revealed that cortical activity during rapid eye movement sleep resembled activity present during monocular deprivation. This corresponded to times of maximal extracellular signal-regulated kinase activation. These findings indicate that rapid eye movement sleep promotes molecular and network adaptations that consolidate waking experience in the developing brain.
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Affiliation(s)
- Michelle C. Dumoulin Bridi
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sara J. Aton
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- University of Michigan, Ann Arbor, MI 48109, USA
| | - Julie Seibt
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Charité–Universitätsmedizin, Berlin 10117, Germany
| | - Leslie Renouard
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- College of Medical Sciences, Washington State University, Spokane, WA 99201, USA
| | - Tammi Coleman
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marcos G. Frank
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- College of Medical Sciences, Washington State University, Spokane, WA 99201, USA
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Abstract
Sleep is hypothesized to play an integral role in brain plasticity. This has traditionally been investigated using behavioral assays. In the last 10-15 years, studies combining sleep measurements with in vitro and in vivo models of synaptic plasticity have provided exciting new insights into how sleep alters synaptic strength. In addition, new theories have been proposed that integrate older ideas about sleep function and recent discoveries in the field of synaptic plasticity. There remain, however, important challenges and unanswered questions. For example, sleep does not appear to have a single effect on synaptic strength. An unbiased review of the literature indicates that the effects of sleep vary widely depending on ontogenetic stage, the type of waking experience (or stimulation protocols) that precede sleep and the type of neuronal synapse under examination. In this review, I discuss these key findings in the context of current theories that posit different roles for sleep in synaptic plasticity.
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Affiliation(s)
- Marcos G Frank
- Department of Neuroscience, School of Medicine, University of Pennsylvania, 215 Stemmler Hall, 35th and Hamilton Walk, Philadelphia, PA, 19104-6074, USA,
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Kelly EA, Opanashuk LA, Majewska AK. The effects of postnatal exposure to low-dose bisphenol-A on activity-dependent plasticity in the mouse sensory cortex. Front Neuroanat 2014; 8:117. [PMID: 25374513 PMCID: PMC4205826 DOI: 10.3389/fnana.2014.00117] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 10/02/2014] [Indexed: 01/03/2023] Open
Abstract
Bisphenol-A (BPA) is a monomer used in the production of polycarbonate plastics, epoxies and resins and is present in many common household objects ranging from water bottles, can linings, baby bottles, and dental resins. BPA exposure has been linked to numerous negative health effects throughout the body, although the mechanisms of BPA action on the developing brain are still poorly understood. In this study, we sought to investigate whether low dose BPA exposure during a developmental phase when brain connectivity is being organized can cause long-term deleterious effects on brain function and plasticity that outlast the BPA exposure. Lactating dams were orally exposed to 25 μg/kg/day of BPA (one half the U.S. Environmental Protection Agency's 50 μg/kg/day rodent dose reference) or vehicle alone from postnatal day (P)5 to P21. Pups exposed to BPA in their mother's milk exhibited deficits in activity-dependent plasticity in the visual cortex during the visual critical period (P28). To determine the possible mechanisms underlying BPA action, we used immunohistochemistry to examine histological markers known to impact cortical maturity and developmental plasticity and quantified cortical dendritic spine density, morphology, and dynamics. While we saw no changes in parvalbumin neuron density, myelin basic protein expression or microglial density in BPA-exposed animals, we observed increases in spine density on apical dendrites in cortical layer five neurons but no significant alterations in other morphological parameters. Taken together our results suggest that exposure to very low levels of BPA during a critical period of brain development can have profound consequences for the normal wiring of sensory circuits and their plasticity later in life.
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Affiliation(s)
- Emily A Kelly
- Department of Neurobiology and Anatomy, Center for Visual Science, School of Medicine and Dentistry, University of Rochester Rochester, NY, USA
| | - Lisa A Opanashuk
- Department of Environmental Medicine, University of Rochester Rochester, NY, USA
| | - Ania K Majewska
- Department of Neurobiology and Anatomy, Center for Visual Science, School of Medicine and Dentistry, University of Rochester Rochester, NY, USA
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Allegra M, Genovesi S, Maggia M, Cenni MC, Zunino G, Sgadò P, Caleo M, Bozzi Y. Altered GABAergic markers, increased binocularity and reduced plasticity in the visual cortex of Engrailed-2 knockout mice. Front Cell Neurosci 2014; 8:163. [PMID: 24987331 PMCID: PMC4060086 DOI: 10.3389/fncel.2014.00163] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 05/29/2014] [Indexed: 01/23/2023] Open
Abstract
The maturation of the GABAergic system is a crucial determinant of cortical development during early postnatal life, when sensory circuits undergo a process of activity-dependent refinement. An altered excitatory/inhibitory balance has been proposed as a possible pathogenic mechanism of autism spectrum disorders (ASD). The homeobox-containing transcription factor Engrailed-2 (En2) has been associated to ASD, and En2 knockout (En2−/−) mice show ASD-like features accompanied by a partial loss of cortical GABAergic interneurons. Here we studied GABAergic markers and cortical function in En2−/− mice, by exploiting the well-known anatomical and functional features of the mouse visual system. En2 is expressed in the visual cortex at postnatal day 30 and during adulthood. When compared to age-matched En2+/+ controls, En2−/− mice showed an increased number of parvalbumin (PV+), somatostatin (SOM+), and neuropeptide Y (NPY+) positive interneurons in the visual cortex at P30, and a decreased number of SOM+ and NPY+ interneurons in the adult. At both ages, the differences in distinct interneuron populations observed between En2+/+ and En2−/− mice were layer-specific. Adult En2−/− mice displayed a normal eye-specific segregation in the retino-geniculate pathway, and in vivo electrophysiological recordings showed a normal development of basic functional properties (acuity, response latency, receptive field size) of the En2−/− primary visual cortex. However, a significant increase of binocularity was found in P30 and adult En2−/− mice, as compared to age-matched controls. Differently from what observed in En2+/+ mice, the En2−/− primary visual cortex did not respond to a brief monocular deprivation performed between P26 and P29, during the so-called “critical period.” These data suggest that altered GABAergic circuits impact baseline binocularity and plasticity in En2−/− mice, while leaving other visual functional properties unaffected.
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Affiliation(s)
- Manuela Allegra
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy ; Laboratory of Neurobiology, Scuola Normale Superiore Pisa, Italy
| | - Sacha Genovesi
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Marika Maggia
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Maria C Cenni
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy
| | - Giulia Zunino
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Paola Sgadò
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
| | - Matteo Caleo
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy
| | - Yuri Bozzi
- Neuroscience Institute, National Research Council (CNR) Pisa, Italy ; Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Mattarello, Trento, Italy
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Sale A, Berardi N, Maffei L. Environment and Brain Plasticity: Towards an Endogenous Pharmacotherapy. Physiol Rev 2014; 94:189-234. [DOI: 10.1152/physrev.00036.2012] [Citation(s) in RCA: 265] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Brain plasticity refers to the remarkable property of cerebral neurons to change their structure and function in response to experience, a fundamental theoretical theme in the field of basic research and a major focus for neural rehabilitation following brain disease. While much of the early work on this topic was based on deprivation approaches relying on sensory experience reduction procedures, major advances have been recently obtained using the conceptually opposite paradigm of environmental enrichment, whereby an enhanced stimulation is provided at multiple cognitive, sensory, social, and motor levels. In this survey, we aim to review past and recent work concerning the influence exerted by the environment on brain plasticity processes, with special emphasis on the underlying cellular and molecular mechanisms and starting from experimental work on animal models to move to highly relevant work performed in humans. We will initiate introducing the concept of brain plasticity and describing classic paradigmatic examples to illustrate how changes at the level of neuronal properties can ultimately affect and direct key perceptual and behavioral outputs. Then, we describe the remarkable effects elicited by early stressful conditions, maternal care, and preweaning enrichment on central nervous system development, with a separate section focusing on neurodevelopmental disorders. A specific section is dedicated to the striking ability of environmental enrichment and physical exercise to empower adult brain plasticity. Finally, we analyze in the last section the ever-increasing available knowledge on the effects elicited by enriched living conditions on physiological and pathological aging brain processes.
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Affiliation(s)
- Alessandro Sale
- Institute of Neuroscience, National Research Council, Pisa, Italy; Department of Psychology, Florence University, Florence, Italy; and Scuola Normale Superiore, Pisa, Italy
| | - Nicoletta Berardi
- Institute of Neuroscience, National Research Council, Pisa, Italy; Department of Psychology, Florence University, Florence, Italy; and Scuola Normale Superiore, Pisa, Italy
| | - Lamberto Maffei
- Institute of Neuroscience, National Research Council, Pisa, Italy; Department of Psychology, Florence University, Florence, Italy; and Scuola Normale Superiore, Pisa, Italy
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Activity-dependent NPAS4 expression and the regulation of gene programs underlying plasticity in the central nervous system. Neural Plast 2013; 2013:683909. [PMID: 24024041 PMCID: PMC3759247 DOI: 10.1155/2013/683909] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 07/09/2013] [Indexed: 11/17/2022] Open
Abstract
The capability of the brain to change functionally in response to sensory experience is most active during early stages of development but it decreases later in life when major alterations of neuronal network structures no longer take place in response to experience. This view has been recently challenged by experimental strategies based on the enhancement of environmental stimulation levels, genetic manipulations, and pharmacological treatments, which all have demonstrated that the adult brain retains a degree of plasticity that allows for a rewiring of neuronal circuitries over the entire life course. A hot spot in the field of neuronal plasticity centres on gene programs that underlie plastic phenomena in adulthood. Here, I discuss the role of the recently discovered neuronal-specific and activity-dependent transcription factor NPAS4 as a critical mediator of plasticity in the nervous system. A better understanding of how modifications in the connectivity of neuronal networks occur may shed light on the treatment of pathological conditions such as brain damage or disease in adult life, some of which were once considered untreatable.
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Neurochemical changes within human early blind occipital cortex. Neuroscience 2013; 252:222-33. [PMID: 23954804 DOI: 10.1016/j.neuroscience.2013.08.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 08/01/2013] [Accepted: 08/02/2013] [Indexed: 01/01/2023]
Abstract
Early blindness results in occipital cortex neurons responding to a wide range of auditory and tactile stimuli. These changes in tuning properties are accompanied by an extensive reorganization of the occipital cortex that includes alterations in anatomical structure, neurochemical and metabolic pathways. Although it has been established in animal models that neurochemical pathways are heavily affected by early visual deprivation, the effects of blindness on these pathways in humans is still not well characterized. Here, using (1)H magnetic resonance spectroscopy in nine early blind and normally sighted subjects, we find that early blindness is associated with higher levels of creatine, choline and myo-Inositol and indications of lower levels of GABA within the occipital cortex. These results suggest that the cross-modal responses associated with early blindness may, at least in part, be driven by changes within occipital biochemical pathways.
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Murthy R, Kim J, Sun X, Giger RJ, Fink DJ, Mata M. Post-transcriptional regulation of GABAB receptor and GIRK1 channels by Nogo receptor 1. Mol Brain 2013; 6:30. [PMID: 23829864 PMCID: PMC3734105 DOI: 10.1186/1756-6606-6-30] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 07/01/2013] [Indexed: 11/10/2022] Open
Abstract
Background Type B GABA receptors (GABA Rs) play a critical role in synaptic transmission. We carried out studies to determine whether neuronal cell surface expression of GABAB-Rs might be regulated by the Nogo receptor 1 (NgR1). Results siRNA knock-down of NgR1 resulted in a selective increase of GABAB R1 and GABAB R2 protein without altering the expression of GABAA receptor or GAD65. The increase in GABAB receptor subunits was unaccompanied by a change in mRNA, but inhibition of mTOR by rapamycin blocked the increase in GABAB protein. NgR1 siRNA also caused an increase in G protein coupled inwardly rectifying potassium channel (GIRK1). The increase in GABAB receptor and GIRK1 channel proteins was in the plasma membrane, determined by cell surface biotinylation. In NgR1 knockout mice, the amount of GABAB R2 and GIRK1 in hippocampus-derived synaptosomes was increased. Conclusions Together these findings suggest that NgR1 mediated modulation of synaptic transmission may be accomplished, at least in part, through modulation of G protein coupled receptors and channels.
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Affiliation(s)
- Rachana Murthy
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System-Neurology and GRECC, 5027 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
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