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Ferreira A, Constantinescu VS, Malvaut S, Saghatelyan A, Hardy SV. Distinct forms of structural plasticity of adult-born interneuron spines in the mouse olfactory bulb induced by different odor learning paradigms. Commun Biol 2024; 7:420. [PMID: 38582915 PMCID: PMC10998910 DOI: 10.1038/s42003-024-06115-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 03/27/2024] [Indexed: 04/08/2024] Open
Abstract
The morpho-functional properties of neural networks constantly adapt in response to environmental stimuli. The olfactory bulb is particularly prone to constant reshaping of neural networks because of ongoing neurogenesis. It remains unclear whether the complexity of distinct odor-induced learning paradigms and sensory stimulation induces different forms of structural plasticity. In the present study, we automatically reconstructed spines in 3D from confocal images and performed unsupervised clustering based on morphometric features. We show that while sensory deprivation decreased the spine density of adult-born neurons without affecting the morphometric properties of these spines, simple and complex odor learning paradigms triggered distinct forms of structural plasticity. A simple odor learning task affected the morphometric properties of the spines, whereas a complex odor learning task induced changes in spine density. Our work reveals distinct forms of structural plasticity in the olfactory bulb tailored to the complexity of odor-learning paradigms and sensory inputs.
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Affiliation(s)
- Aymeric Ferreira
- CERVO Brain Research Center, Quebec City, QC, G1J 2G3, Canada
- Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, QC, G1V 0A6, Canada
| | - Vlad-Stefan Constantinescu
- CERVO Brain Research Center, Quebec City, QC, G1J 2G3, Canada
- Department of Psychiatry and Neuroscience, Université Laval, Quebec City, QC, G1V 0A6, Canada
| | - Sarah Malvaut
- CERVO Brain Research Center, Quebec City, QC, G1J 2G3, Canada
- Department of Psychiatry and Neuroscience, Université Laval, Quebec City, QC, G1V 0A6, Canada
| | - Armen Saghatelyan
- CERVO Brain Research Center, Quebec City, QC, G1J 2G3, Canada.
- Department of Psychiatry and Neuroscience, Université Laval, Quebec City, QC, G1V 0A6, Canada.
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
| | - Simon V Hardy
- CERVO Brain Research Center, Quebec City, QC, G1J 2G3, Canada.
- Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, QC, G1V 0A6, Canada.
- Department of Computer Science and Software Engineering, Université Laval, Quebec City, QC, G1V 0A6, Canada.
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2
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Huang Y, Zhang X, Li W. Involvement of primary somatosensory cortex in motor learning and task execution. Neurosci Lett 2024; 828:137753. [PMID: 38554843 DOI: 10.1016/j.neulet.2024.137753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/25/2024] [Accepted: 03/27/2024] [Indexed: 04/02/2024]
Abstract
The primary somatosensory cortex (S1) is responsible for processing information related to tactile stimulation, motor learning and control. Despite its significance, the connection between S1 and the primary motor cortex (M1), as well as its role in motor learning, remains a topic of ongoing exploration. In the present study, we silenced S1 by the GABA receptor agonist muscimol to study the potential roles of S1 in motor learning and task execution. Our results show that the inhibition of S1 leads to an immediate impairment in performance during the training session and also a substantial reduction in performance improvement during post-test session on the subsequent day. To understand the underlying mechanism, we used intravital two-photon imaging to investigate the dynamics of dendritic spines of layer V pyramidal neurons and the calcium activities of pyramidal neurons in M1 after inhibition of S1. Notably, S1 inhibition reduces motor training-induced spine formation and facilitates the elimination of existing spines of layer V pyramidal neurons in M1. The calcium activities in M1 exhibit a significant decrease during both resting and running periods following S1 inhibition. Furthermore, inhibition of S1, but not M1, significantly impairs the execution of the acquired motor task in the well-trained animals. Together, these findings reveal that S1 plays important roles in motor learning and task execution.
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Affiliation(s)
- Yunxuan Huang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen 518107, China
| | - Xiaoyu Zhang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen 518107, China
| | - Wei Li
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen 518107, China; School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
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3
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Kogan E, Lu J, Zuo Y. Cortical circuit dynamics underlying motor skill learning: from rodents to humans. Front Mol Neurosci 2023; 16:1292685. [PMID: 37965043 PMCID: PMC10641381 DOI: 10.3389/fnmol.2023.1292685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/11/2023] [Indexed: 11/16/2023] Open
Abstract
Motor learning is crucial for the survival of many animals. Acquiring a new motor skill involves complex alterations in both local neural circuits in many brain regions and long-range connections between them. Such changes can be observed anatomically and functionally. The primary motor cortex (M1) integrates information from diverse brain regions and plays a pivotal role in the acquisition and refinement of new motor skills. In this review, we discuss how motor learning affects the M1 at synaptic, cellular, and circuit levels. Wherever applicable, we attempt to relate and compare findings in humans, non-human primates, and rodents. Understanding the underlying principles shared by different species will deepen our understanding of the neurobiological and computational basis of motor learning.
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Affiliation(s)
| | | | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
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4
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Shinotsuka T, Tanaka YR, Terada SI, Hatano N, Matsuzaki M. Layer 5 Intratelencephalic Neurons in the Motor Cortex Stably Encode Skilled Movement. J Neurosci 2023; 43:7130-7148. [PMID: 37699714 PMCID: PMC10601372 DOI: 10.1523/jneurosci.0428-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 07/29/2023] [Accepted: 08/26/2023] [Indexed: 09/14/2023] Open
Abstract
The primary motor cortex (M1) and the dorsal striatum play a critical role in motor learning and the retention of learned behaviors. Motor representations of corticostriatal ensembles emerge during motor learning. In the coordinated reorganization of M1 and the dorsal striatum for motor learning, layer 5a (L5a) which connects M1 to the ipsilateral and contralateral dorsal striatum, should be a key layer. Although M1 L5a neurons represent movement-related activity in the late stage of learning, it is unclear whether the activity is retained as a memory engram. Here, using Tlx3-Cre male transgenic mice, we conducted two-photon calcium imaging of striatum-projecting L5a intratelencephalic (IT) neurons in forelimb M1 during late sessions of a self-initiated lever-pull task and in sessions after 6 d of nontraining following the late sessions. We found that trained male animals exhibited stable motor performance before and after the nontraining days. At the same time, we found that M1 L5a IT neurons strongly represented the well-learned forelimb movement but not uninstructed orofacial movements. A subset of M1 L5a IT neurons consistently coded the well-learned forelimb movement before and after the nontraining days. Inactivation of M1 IT neurons after learning impaired task performance when the lever was made heavier or when the target range of the pull distance was narrowed. These results suggest that a subset of M1 L5a IT neurons continuously represent skilled movement after learning and serve to fine-tune the kinematics of well-learned movement.SIGNIFICANCE STATEMENT Motor memory persists even when it is not used for a while. IT neurons in L5a of the M1 gradually come to represent skilled forelimb movements during motor learning. However, it remains to be determined whether these changes persist over a long period and how these neurons contribute to skilled movements. Here, we show that a subset of M1 L5a IT neurons retain information for skilled forelimb movements even after nontraining days. Furthermore, suppressing the activity of these neurons during skilled forelimb movements impaired behavioral stability and adaptability. Our results suggest the importance of M1 L5a IT neurons for tuning skilled forelimb movements over a long period.
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Affiliation(s)
- Takanori Shinotsuka
- Department of Physiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Yasuhiro R Tanaka
- Department of Physiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
- Brain Science Institute, Tamagawa University, Machida, Tokyo 194-8610, Japan
| | - Shin-Ichiro Terada
- Department of Physiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Natsuki Hatano
- Department of Physiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Masanori Matsuzaki
- Department of Physiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
- International Research Center for Neurointelligence, University of Tokyo Institutes for Advanced Study, Tokyo 113-0033, Japan
- Brain Functional Dynamics Collaboration Laboratory, RIKEN Center for Brain Science, Saitama 351-0198, Japan
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5
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Vega-Rivera NM, González-Trujano ME, Luna-Angula A, Sánchez-Chapul L, Estrada-Camarena E. Antidepressant-like effects of the Punica granatum and citalopram combination are associated with structural changes in dendritic spines of granule cells in the dentate gyrus of rats. Front Pharmacol 2023; 14:1211663. [PMID: 37900157 PMCID: PMC10613096 DOI: 10.3389/fphar.2023.1211663] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/31/2023] [Indexed: 10/31/2023] Open
Abstract
Introduction: Natural products such as phytoestrogens-enriched foods or supplements have been considered as an alternative therapy to reduce depressive symptoms associated with menopause. It is known that the aqueous extract of Punica granatum (AE-PG) exerts antidepressant-like effects by activating β-estrogen receptors and facilitates the antidepressant response of the clinical drug citalopram (CIT). However, the effects on neuroplasticity are unknown. Objectvie investigated the antidepressant-like response of combining AE-PG and CIT at sub-optimal doses, analyzing their effects on the formation and maturation of dendrite spines in granule cells as well as on the dendrite complexity. Methods: Ovariectomized Wistar rats (3-month-old) were randomly assigned to one of the following groups: A) control (saline solution as vehicle of CIT and AE-PG, B) AE-PG at a sub-threshold dose (vehicle of CIT plus AE-PG at 0.125 mg/kg), C) CIT at a sub-threshold dose (0.77 mg/kg plus vehicle of AE-PG), and D) a combination of CIT plus AE-PG (0.125 mg/kg and 0.77 mg/kg, respectively). All rats were treated intraperitoneally for 14 days. Antidepressant-like effects were evaluated using the force swimming test test (FST). The complexity of dendrites and the number and morphology of dendrite spines of neurons were assessed in the dentate gyrus after Golgi-Cox impregnation. The expressions of the mature brain-derived neurotrophic factor (mBDNF) in plasma and of mBDNF and synaptophysin in the hippocampus, as markers of synaptogenesis, were also determined. Results: Administration of CIT combined with AE-PG, but not alone, induced a significant antidepressant-like effect in the FST with an increase in the dendritic complexity and the number of dendritic spines in the dentate gyrus (DG) of the hippocampus, revealed by the thin and stubby categories of neurons at the granular cell layer. At the same time, an increase of mBDNF and synaptophysin expression was observed in the hippocampus of rats that received the combination of AE-PG and CIT.
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Affiliation(s)
- Nelly-Maritza Vega-Rivera
- Laboratorio de Neuropsicofarmacología, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría “Ramón de la Fuente Muñiz”, Mexico City, Mexico
| | - María Eva González-Trujano
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Alexandra Luna-Angula
- Laboratorio de Enfermedades Neuromusculares, División de Neurociencias Clínicas, Instituto Nacional de Rehabilitación “Luis Guillermo Ibarra Ibarra”, Mexico City, Mexico
| | - Laura Sánchez-Chapul
- Laboratorio de Enfermedades Neuromusculares, División de Neurociencias Clínicas, Instituto Nacional de Rehabilitación “Luis Guillermo Ibarra Ibarra”, Mexico City, Mexico
| | - Erika Estrada-Camarena
- Laboratorio de Neuropsicofarmacología, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría “Ramón de la Fuente Muñiz”, Mexico City, Mexico
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Lu K, Li C, Liu J, Wang J, Li Y, He B, Li J, Zhang X, Wei M, Tian Y, Zhang R, Zhang C, Zhang Y. Impairments in endogenous AMPA receptor dynamics correlates with learning deficits in Alzheimer's disease model mice. Proc Natl Acad Sci U S A 2023; 120:e2303878120. [PMID: 37748061 PMCID: PMC10556575 DOI: 10.1073/pnas.2303878120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/29/2023] [Indexed: 09/27/2023] Open
Abstract
AMPA receptors (AMPARs) play a critical role in synaptic plasticity and learning and memory, and dysfunction or dysregulation of AMPARs could lead to various neurological and psychiatric disorders, such as Alzheimer's disease (AD). However, the dynamics and/or longitudinal changes of AMPARs in vivo during AD pathogenesis remain elusive. Here, employing 5xFAD SEP-GluA1 KI mice, we investigated endogenous AMPA receptor dynamics in a whisker deflection-associated Go/No-go learning paradigm. We found a significant increase in synaptosomal AMPA receptor subunits GluA1 in WT mice after learning, while no such changes were detected in 7-mo-old 5xFAD mice. Daily training led to an increase in endogenous spine surface GluA1 in Control mice, while this increase was absent in 5xFAD-KI mice which correlates with its learning defects in Go/No-go paradigm. Furthermore, we demonstrated that the onset of abnormal AMPAR dynamics corresponds temporally with microglia and astrocyte overactivation. Our results have shown that impairments in endogenous AMPA receptor dynamics play an important role in learning deficits in 5xFAD mice and AD pathogenesis.
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Affiliation(s)
- Kongjie Lu
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
| | - Chenyang Li
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
| | - Jiao Liu
- Center of Medical and Health Analysis, Peking University Health Science Center, Beijing100083, China
| | - Jinpeng Wang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
| | - Yongfeng Li
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
| | - Bin He
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
| | - Junzhao Li
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
| | - Xiaochen Zhang
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin300072, China
| | - Mengping Wei
- School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing100069, China
| | - Yonglu Tian
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
- School of Psychological and Cognitive Sciences, Peking University, Beijing100871, China
| | - Rong Zhang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
| | - Chen Zhang
- School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing100069, China
| | - Yong Zhang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Key Laboratory for Neuroscience, Ministry of Education of China and National Health Commission of the People’s Republic of China, Beijing100083, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing100871, China
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7
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Wang M, Yu X. Experience-dependent structural plasticity of pyramidal neurons in the developing sensory cortices. Curr Opin Neurobiol 2023; 81:102724. [PMID: 37068383 DOI: 10.1016/j.conb.2023.102724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 04/19/2023]
Abstract
Sensory experience regulates the structural and functional wiring of neuronal circuits, during development and throughout adulthood. Here, we review current knowledge of how experience affects structural plasticity of pyramidal neurons in the sensory cortices. We discuss the pros and cons of existing labeling approaches, as well as what structural parameters are most plastic. We further discuss how recent advances in sparse labeling of specific neuronal subtypes, as well as development of techniques that allow fast, high resolution imaging in large fields, would enable future studies to address currently unanswered questions in the field of structural plasticity.
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Affiliation(s)
- Miao Wang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, and PKU-IDG/McGovern Institute, Peking University, Beijing 100871, China.
| | - Xiang Yu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, and PKU-IDG/McGovern Institute, Peking University, Beijing 100871, China; Autism Research Center of Peking University Health Science Center, Beijing 100191, China; Chinese Institute for Brain Research, Beijing 102206, China.
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8
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Wang S, Ning H, Wang X, Chen L, Hua L, Ren F, Hu D, Li R, Ma Z, Ge Y, Yin Z. Exposure to bisphenol A induces neurotoxicity associated with synaptic and cytoskeletal dysfunction in neuro-2a cells. Toxicol Ind Health 2023; 39:325-335. [PMID: 37122122 DOI: 10.1177/07482337231172827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Bisphenol A (BPA) has been reported to injure the developing and adult brain. However, the underlying mechanism still remains elusive. This study used neuro-2a cells as a cellular model to investigate the neurotoxic effects of BPA. Microtubule-associated protein 2 (MAP2) and tau protein maintain microtubule normal function and promote the normal development of the nervous system. Synaptophysin (SYP) and drebrin (Dbn) proteins are involved in regulating synaptic plasticity. Cells were exposed to the minimum essential medium (MEM), 0.01% (v/v) DMSO, and 150 μM BPA for 12, 24, or 36 h. Morphological analysis revealed that the cells in the BPA-treated groups shrank and collapsed compared with those in the control groups. CCK-8 and lactate dehydrogenase assay (LDH) assays showed that the mortality of neuro-2a cells increased as the BPA treatment time was prolonged. Ultrastructural analysis further revealed that cells demonstrated nucleolar swelling, dissolution of nuclear and mitochondrial membranes, and partial mitochondrial condensation following exposure to BPA. BPA also decreased the relative protein expression levels of MAP2, tau, and Dbn. Interestingly, the relative protein expression levels of SYP increased. These results indicated that BPA inhibited the proliferation and disrupted cytoskeleton and synaptic integrity of neuro-2a cells.
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Affiliation(s)
- Siting Wang
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Hongmei Ning
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Xinrui Wang
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Lingli Chen
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Liushuai Hua
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Fei Ren
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Dongfang Hu
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Rongbo Li
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Zhisheng Ma
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Yaming Ge
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
| | - Zhihong Yin
- College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, Henan, P. R. China
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9
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Qin S, Farashahi S, Lipshutz D, Sengupta AM, Chklovskii DB, Pehlevan C. Coordinated drift of receptive fields in Hebbian/anti-Hebbian network models during noisy representation learning. Nat Neurosci 2023; 26:339-349. [PMID: 36635497 DOI: 10.1038/s41593-022-01225-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 10/28/2022] [Indexed: 01/13/2023]
Abstract
Recent experiments have revealed that neural population codes in many brain areas continuously change even when animals have fully learned and stably perform their tasks. This representational 'drift' naturally leads to questions about its causes, dynamics and functions. Here we explore the hypothesis that neural representations optimize a representational objective with a degenerate solution space, and noisy synaptic updates drive the network to explore this (near-)optimal space causing representational drift. We illustrate this idea and explore its consequences in simple, biologically plausible Hebbian/anti-Hebbian network models of representation learning. We find that the drifting receptive fields of individual neurons can be characterized by a coordinated random walk, with effective diffusion constants depending on various parameters such as learning rate, noise amplitude and input statistics. Despite such drift, the representational similarity of population codes is stable over time. Our model recapitulates experimental observations in the hippocampus and posterior parietal cortex and makes testable predictions that can be probed in future experiments.
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Affiliation(s)
- Shanshan Qin
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Shiva Farashahi
- Center for Computational Neuroscience, Flatiron Institute, New York, NY, USA
| | - David Lipshutz
- Center for Computational Neuroscience, Flatiron Institute, New York, NY, USA
| | - Anirvan M Sengupta
- Center for Computational Neuroscience, Flatiron Institute, New York, NY, USA
- Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ, USA
| | - Dmitri B Chklovskii
- Center for Computational Neuroscience, Flatiron Institute, New York, NY, USA
- NYU Langone Medical Center, New York, NY, USA
| | - Cengiz Pehlevan
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
- Center for Brain Science, Harvard University, Cambridge, MA, USA.
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10
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Murthy BKB, Somatakis S, Ulivi AF, Klimmt H, Castello-Waldow TP, Haynes N, Huettl RE, Chen A, Attardo A. Arc-driven mGRASP highlights CA1 to CA3 synaptic engrams. Front Behav Neurosci 2023; 16:1072571. [PMID: 36793796 PMCID: PMC9924068 DOI: 10.3389/fnbeh.2022.1072571] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/29/2022] [Indexed: 02/03/2023] Open
Abstract
Subpopulations of neurons display increased activity during memory encoding and manipulating the activity of these neurons can induce artificial formation or erasure of memories. Thus, these neurons are thought to be cellular engrams. Moreover, correlated activity between pre- and postsynaptic engram neurons is thought to lead to strengthening of their synaptic connections, thus increasing the probability of neural activity patterns occurring during encoding to reoccur at recall. Therefore, synapses between engram neurons can also be considered as a substrate of memory, or a synaptic engram. One can label synaptic engrams by targeting two complementary, non-fluorescent, synapse-targeted GFP fragments separately to the pre- and postsynaptic compartment of engram neurons; the two GFP fragments reconstitute a fluorescent GFP at the synaptic cleft between the engram neurons, thereby highlighting synaptic engrams. In this work we explored a transsynaptic GFP reconstitution system (mGRASP) to label synaptic engrams between hippocampal CA1 and CA3 engram neurons identified by different Immediate-Early Genes: cFos and Arc. We characterized the expression of the cellular and synaptic labels of the mGRASP system upon exposure to a novel environment or learning of a hippocampal-dependent memory task. We found that mGRASP under the control of transgenic ArcCreERT2 labeled synaptic engrams more efficiently than when controlled by viral cFostTA, possibly due to differences in the genetic systems rather than the specific IEG promoters.
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Affiliation(s)
- B. K. B. Murthy
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany
| | - S. Somatakis
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A. F. Ulivi
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Max Planck Institute of Psychiatry, Munich, Germany
| | - H. Klimmt
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany
| | | | - N. Haynes
- Max Planck Institute of Psychiatry, Munich, Germany
| | - R. E. Huettl
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A. Chen
- Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany,Weizmann Institute of Science, Rehovot, Israel
| | - Alessio Attardo
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany,*Correspondence: Alessio Attardo,
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11
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Su F, Wei M, Sun M, Jiang L, Dong Z, Wang J, Zhang C. Deep learning-based synapse counting and synaptic ultrastructure analysis of electron microscopy images. J Neurosci Methods 2023; 384:109750. [PMID: 36414102 DOI: 10.1016/j.jneumeth.2022.109750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/11/2022] [Accepted: 11/18/2022] [Indexed: 11/21/2022]
Abstract
BACKGROUND Synapses are the connections between neurons in the central nervous system (CNS) or between neurons and other excitable cells in the peripheral nervous system (PNS), where electrical or chemical signals rapidly travel through one cell to another with high spatial precision. Synaptic analysis, based on synapse numbers and fine morphology, is the basis for understanding neurological functions and diseases. Manual analysis of synaptic structures in electron microscopy (EM) images is often limited by low efficiency and subjective bias. NEW METHOD We developed a multifunctional synaptic analysis system based on several advanced deep learning (DL) models. The system achieved synapse counting in low-magnification EM images and synaptic ultrastructure analysis in high-magnification EM images. RESULTS The synapse counting system based on ResNet18 and a Faster R-CNN model had a mean average precision (mAP) of 92.55%. For synaptic ultrastructure analysis, the Faster R-CNN model based on ResNet50 achieved a mAP of 91.60%, the DeepLab v3 + model based on ResNet50 enabled high performance in presynaptic and postsynaptic membrane segmentation with a global accuracy of 0.9811, and the Faster R-CNN model based on ResNet18 achieved a mAP of 91.41% for synaptic vesicle detection. CONCLUSIONS The proposed multifunctional synaptic analysis system may help to overcome the experimental bias inherent in manual analysis, thereby facilitating EM image-based synaptic function studies.
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Affiliation(s)
- Feng Su
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China; Chinese Institute for Brain Research, Beijing 102206, China; State Key Laboratory of Translational Medicine and Innovative Drug Development, Nanjing 210000, Jiangsu, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Mengping Wei
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Meng Sun
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Lixin Jiang
- Peking University Institute of Mental Health (Sixth Hospital), No. 51 Huayuanbei Road, Haidian District, Beijing 100191, China
| | - Zhaoqi Dong
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Jue Wang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Chen Zhang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China; Chinese Institute for Brain Research, Beijing 102206, China; State Key Laboratory of Translational Medicine and Innovative Drug Development, Nanjing 210000, Jiangsu, China.
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12
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KASAI H. Unraveling the mysteries of dendritic spine dynamics: Five key principles shaping memory and cognition. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2023; 99:254-305. [PMID: 37821392 PMCID: PMC10749395 DOI: 10.2183/pjab.99.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 07/11/2023] [Indexed: 10/13/2023]
Abstract
Recent research extends our understanding of brain processes beyond just action potentials and chemical transmissions within neural circuits, emphasizing the mechanical forces generated by excitatory synapses on dendritic spines to modulate presynaptic function. From in vivo and in vitro studies, we outline five central principles of synaptic mechanics in brain function: P1: Stability - Underpinning the integral relationship between the structure and function of the spine synapses. P2: Extrinsic dynamics - Highlighting synapse-selective structural plasticity which plays a crucial role in Hebbian associative learning, distinct from pathway-selective long-term potentiation (LTP) and depression (LTD). P3: Neuromodulation - Analyzing the role of G-protein-coupled receptors, particularly dopamine receptors, in time-sensitive modulation of associative learning frameworks such as Pavlovian classical conditioning and Thorndike's reinforcement learning (RL). P4: Instability - Addressing the intrinsic dynamics crucial to memory management during continual learning, spotlighting their role in "spine dysgenesis" associated with mental disorders. P5: Mechanics - Exploring how synaptic mechanics influence both sides of synapses to establish structural traces of short- and long-term memory, thereby aiding the integration of mental functions. We also delve into the historical background and foresee impending challenges.
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Affiliation(s)
- Haruo KASAI
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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13
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Petanjek Z, Banovac I, Sedmak D, Hladnik A. Dendritic Spines: Synaptogenesis and Synaptic Pruning for the Developmental Organization of Brain Circuits. ADVANCES IN NEUROBIOLOGY 2023; 34:143-221. [PMID: 37962796 DOI: 10.1007/978-3-031-36159-3_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Synaptic overproduction and elimination is a regular developmental event in the mammalian brain. In the cerebral cortex, synaptic overproduction is almost exclusively correlated with glutamatergic synapses located on dendritic spines. Therefore, analysis of changes in spine density on different parts of the dendritic tree in identified classes of principal neurons could provide insight into developmental reorganization of specific microcircuits.The activity-dependent stabilization and selective elimination of the initially overproduced synapses is a major mechanism for generating diversity of neural connections beyond their genetic determination. The largest number of overproduced synapses was found in the monkey and human cerebral cortex. The highest (exceeding adult values by two- to threefold) and most protracted overproduction (up to third decade of life) was described for associative layer IIIC pyramidal neurons in the human dorsolateral prefrontal cortex.Therefore, the highest proportion and extraordinarily extended phase of synaptic spine overproduction is a hallmark of neural circuitry in human higher-order associative areas. This indicates that microcircuits processing the most complex human cognitive functions have the highest level of developmental plasticity. This finding is the backbone for understanding the effect of environmental impact on the development of the most complex, human-specific cognitive and emotional capacities, and on the late onset of human-specific neuropsychiatric disorders, such as autism and schizophrenia.
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Affiliation(s)
- Zdravko Petanjek
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia.
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia.
| | - Ivan Banovac
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Dora Sedmak
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Ana Hladnik
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
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14
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Hristovska I, Robert M, Combet K, Honnorat J, Comte JC, Pascual O. Sleep decreases neuronal activity control of microglial dynamics in mice. Nat Commun 2022; 13:6273. [PMID: 36271013 PMCID: PMC9586953 DOI: 10.1038/s41467-022-34035-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 10/12/2022] [Indexed: 12/25/2022] Open
Abstract
Microglia, the brain-resident immune cells, are highly ramified with dynamic processes transiently contacting synapses. These contacts have been reported to be activity-dependent, but this has not been thoroughly studied yet, especially in physiological conditions. Here we investigate neuron-microglia contacts and microglia morphodynamics in mice in an activity-dependent context such as the vigilance states. We report that microglial morphodynamics and microglia-spine contacts are regulated by spontaneous and evoked neuronal activity. We also found that sleep modulates microglial morphodynamics through Cx3cr1 signaling. At the synaptic level, microglial processes are attracted towards active spines during wake, and this relationship is hindered during sleep. Finally, microglial contact increases spine activity, mainly during NREM sleep. Altogether, these results indicate that microglial function at synapses is dependent on neuronal activity and the vigilance states, providing evidence that microglia could be important for synaptic homeostasis and plasticity.
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Affiliation(s)
- I. Hristovska
- INSERM U1314, CNRS UMR5284, MeLiS, Lyon, France ,grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, Lyon, France
| | - M. Robert
- INSERM U1314, CNRS UMR5284, MeLiS, Lyon, France ,grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, Lyon, France ,grid.414243.40000 0004 0597 9318French Reference Center on Paraneoplastic Neurological Syndromes and Autoimmune Encephalitis, Hospices Civils de Lyon, Hôpital Neurologique, 59 Boulevard Pinel, 69677 Bron, Cedex France
| | - K. Combet
- INSERM U1314, CNRS UMR5284, MeLiS, Lyon, France ,grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, Lyon, France
| | - J. Honnorat
- INSERM U1314, CNRS UMR5284, MeLiS, Lyon, France ,grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, Lyon, France ,grid.414243.40000 0004 0597 9318French Reference Center on Paraneoplastic Neurological Syndromes and Autoimmune Encephalitis, Hospices Civils de Lyon, Hôpital Neurologique, 59 Boulevard Pinel, 69677 Bron, Cedex France
| | - J-C Comte
- grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, Lyon, France ,grid.461862.f0000 0004 0614 7222INSERM U1028, CNRS UMR5292, Lyon, France ,Centre de Recherche en Neuroscience de Lyon, Lyon, France
| | - O. Pascual
- INSERM U1314, CNRS UMR5284, MeLiS, Lyon, France ,grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, Lyon, France
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15
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Qi C, Luo LD, Feng I, Ma S. Molecular mechanisms of synaptogenesis. Front Synaptic Neurosci 2022; 14:939793. [PMID: 36176941 PMCID: PMC9513053 DOI: 10.3389/fnsyn.2022.939793] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/27/2022] [Indexed: 11/29/2022] Open
Abstract
Synapses are the basic units for information processing and storage in the nervous system. It is only when the synaptic connection is established, that it becomes meaningful to discuss the structure and function of a circuit. In humans, our unparalleled cognitive abilities are correlated with an increase in the number of synapses. Additionally, genes involved in synaptogenesis are also frequently associated with neurological or psychiatric disorders, suggesting a relationship between synaptogenesis and brain physiology and pathology. Thus, understanding the molecular mechanisms of synaptogenesis is the key to the mystery of circuit assembly and neural computation. Furthermore, it would provide therapeutic insights for the treatment of neurological and psychiatric disorders. Multiple molecular events must be precisely coordinated to generate a synapse. To understand the molecular mechanisms underlying synaptogenesis, we need to know the molecular components of synapses, how these molecular components are held together, and how the molecular networks are refined in response to neural activity to generate new synapses. Thanks to the intensive investigations in this field, our understanding of the process of synaptogenesis has progressed significantly. Here, we will review the molecular mechanisms of synaptogenesis by going over the studies on the identification of molecular components in synapses and their functions in synaptogenesis, how cell adhesion molecules connect these synaptic molecules together, and how neural activity mobilizes these molecules to generate new synapses. Finally, we will summarize the human-specific regulatory mechanisms in synaptogenesis and results from human genetics studies on synaptogenesis and brain disorders.
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Affiliation(s)
- Cai Qi
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, United States
- *Correspondence: Cai Qi,
| | - Li-Da Luo
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, United States
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, United States
| | - Irena Feng
- Boston University School of Medicine, Boston, MA, United States
| | - Shaojie Ma
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, United States
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16
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Juvenile depletion of microglia reduces orientation but not high spatial frequency selectivity in mouse V1. Sci Rep 2022; 12:12779. [PMID: 35896554 PMCID: PMC9329297 DOI: 10.1038/s41598-022-15503-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/24/2022] [Indexed: 01/26/2023] Open
Abstract
Microglia contain multiple mechanisms that shape the synaptic landscape during postnatal development. Whether the synaptic changes mediated by microglia reflect the developmental refinement of neuronal responses in sensory cortices, however, remains poorly understood. In postnatal life, the development of increased orientation and spatial frequency selectivity of neuronal responses in primary visual cortex (V1) supports the emergence of high visual acuity. Here, we used the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 to rapidly and durably deplete microglia in mice during the juvenile period in which increased orientation and spatial frequency selectivity emerge. Excitatory and inhibitory tuning properties were measured simultaneously using multi-photon calcium imaging in layer II/III of mouse V1. We found that microglia depletion generally increased evoked activity which, in turn, reduced orientation selectivity. Surprisingly, microglia were not required for the emergence of high spatial frequency tuned responses. In addition, microglia depletion did not perturb cortical binocularity, suggesting normal depth processing. Together, our finding that orientation and high spatial frequency selectivity in V1 are differentially supported by microglia reveal that microglia are required normal sensory processing, albeit selectively.
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17
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Chen CC, Brumberg JC. Sensory Experience as a Regulator of Structural Plasticity in the Developing Whisker-to-Barrel System. Front Cell Neurosci 2022; 15:770453. [PMID: 35002626 PMCID: PMC8739903 DOI: 10.3389/fncel.2021.770453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 11/22/2021] [Indexed: 12/28/2022] Open
Abstract
Cellular structures provide the physical foundation for the functionality of the nervous system, and their developmental trajectory can be influenced by the characteristics of the external environment that an organism interacts with. Historical and recent works have determined that sensory experiences, particularly during developmental critical periods, are crucial for information processing in the brain, which in turn profoundly influence neuronal and non-neuronal cortical structures that subsequently impact the animals' behavioral and cognitive outputs. In this review, we focus on how altering sensory experience influences normal/healthy development of the central nervous system, particularly focusing on the cerebral cortex using the rodent whisker-to-barrel system as an illustrative model. A better understanding of structural plasticity, encompassing multiple aspects such as neuronal, glial, and extra-cellular domains, provides a more integrative view allowing for a deeper appreciation of how all aspects of the brain work together as a whole.
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Affiliation(s)
- Chia-Chien Chen
- Department of Psychology, Queens College City University of New York, Flushing, NY, United States.,Department of Neuroscience, Duke Kunshan University, Suzhou, China
| | - Joshua C Brumberg
- Department of Psychology, Queens College City University of New York, Flushing, NY, United States.,The Biology (Neuroscience) and Psychology (Behavioral and Cognitive Neuroscience) PhD Programs, The Graduate Center, The City University of New York, New York, NY, United States
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18
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Long-lasting Postnatal Sensory Deprivation Alters Dendritic Morphology of Pyramidal Neurons in the Rat Hippocampus: Behavioral Correlates. Neuroscience 2022; 480:79-96. [PMID: 34785272 DOI: 10.1016/j.neuroscience.2021.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 11/20/2022]
Abstract
The role of normal sensory inputs in the development of sensory cortices is well known, however, their impacts on the hippocampus, an integrator of sensory modalities with important roles in cognitive functions, has received much less attention. Here, we applied a long-term sensory deprivation paradigm by trimming the rats' whiskers bilaterally, from postnatal day 3 to 59. Female sensory-deprived (SD) rats showed more on-wall rearing and visits to the center of the open-field box, shorter periods of grooming, less defecation and less anxiety-like behaviors in the elevated plus-maze compared to controls, who had their intact whiskers brushed. Passive avoidance memory retention was sex-dependently impaired in the female SD rats. In the radial arm maze, however, reference spatial memory was impaired only in the male SD rats. Nonetheless, working memory errors increased in both sexes of SD rats. Besides depletion of CA1 and CA3 pyramidal neurons in SD rats, Sholl analysis of Golgi-Cox stained neurons revealed that prolonged sensory deprivation has retracted the arborization of CA1 basal dendrites in SD group, while solely female SD rats had diminished CA1 apical dendrites. Sholl analysis of CA3 neurons in SD animals also disclosed significantly more branched apical dendrites in males and basal dendrites in females. Sensory deprivation also led to a considerable spine loss and variation of different spine types in a sex-dependent manner. Our findings suggest that experience-dependent structural plasticity is capable of spreading far beyond the manipulated sensory zones and the inevitable functional alterations can be expressed in a multifactorial sex-dependent manner.
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19
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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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20
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Sleep promotes the formation of dendritic filopodia and spines near learning-inactive existing spines. Proc Natl Acad Sci U S A 2021; 118:2114856118. [PMID: 34873044 DOI: 10.1073/pnas.2114856118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2021] [Indexed: 01/20/2023] Open
Abstract
Changes in synaptic connections are believed to underlie long-term memory storage. Previous studies have suggested that sleep is important for synapse formation after learning, but how sleep is involved in the process of synapse formation remains unclear. To address this question, we used transcranial two-photon microscopy to investigate the effect of postlearning sleep on the location of newly formed dendritic filopodia and spines of layer 5 pyramidal neurons in the primary motor cortex of adolescent mice. We found that newly formed filopodia and spines were partially clustered with existing spines along individual dendritic segments 24 h after motor training. Notably, posttraining sleep was critical for promoting the formation of dendritic filopodia and spines clustered with existing spines within 8 h. A fraction of these filopodia was converted into new spines and contributed to clustered spine formation 24 h after motor training. This sleep-dependent spine formation via filopodia was different from retraining-induced new spine formation, which emerged from dendritic shafts without prior presence of filopodia. Furthermore, sleep-dependent new filopodia and spines tended to be formed away from existing spines that were active at the time of motor training. Taken together, these findings reveal a role of postlearning sleep in regulating the number and location of new synapses via promoting filopodial formation.
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21
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Melander JB, Nayebi A, Jongbloets BC, Fortin DA, Qin M, Ganguli S, Mao T, Zhong H. Distinct in vivo dynamics of excitatory synapses onto cortical pyramidal neurons and parvalbumin-positive interneurons. Cell Rep 2021; 37:109972. [PMID: 34758304 PMCID: PMC8631347 DOI: 10.1016/j.celrep.2021.109972] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 09/03/2021] [Accepted: 10/19/2021] [Indexed: 11/18/2022] Open
Abstract
Cortical function relies on the balanced activation of excitatory and inhibitory neurons. However, little is known about the organization and dynamics of shaft excitatory synapses onto cortical inhibitory interneurons. Here, we use the excitatory postsynaptic marker PSD-95, fluorescently labeled at endogenous levels, as a proxy for excitatory synapses onto layer 2/3 pyramidal neurons and parvalbumin-positive (PV+) interneurons in the barrel cortex of adult mice. Longitudinal in vivo imaging under baseline conditions reveals that, although synaptic weights in both neuronal types are log-normally distributed, synapses onto PV+ neurons are less heterogeneous and more stable. Markov model analyses suggest that the synaptic weight distribution is set intrinsically by ongoing cell-type-specific dynamics, and substantial changes are due to accumulated gradual changes. Synaptic weight dynamics are multiplicative, i.e., changes scale with weights, although PV+ synapses also exhibit an additive component. These results reveal that cell-type-specific processes govern cortical synaptic strengths and dynamics. Melander et al. use a genetic strategy to visualize excitatory neuronal connections that cannot be inferred from morphology, and they monitor how the connections change over weeks in mice. They find distinct characteristics between synapses onto cells that “suppress” brain activity and those onto cells that “excite” brain activity.
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Affiliation(s)
- Joshua B Melander
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA; Neurosciences PhD Program, Stanford University, Stanford, CA 94305, USA
| | - Aran Nayebi
- Neurosciences PhD Program, Stanford University, Stanford, CA 94305, USA
| | - Bart C Jongbloets
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Dale A Fortin
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Maozhen Qin
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Surya Ganguli
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
| | - Tianyi Mao
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
| | - Haining Zhong
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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22
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Faust TE, Gunner G, Schafer DP. Mechanisms governing activity-dependent synaptic pruning in the developing mammalian CNS. Nat Rev Neurosci 2021; 22:657-673. [PMID: 34545240 PMCID: PMC8541743 DOI: 10.1038/s41583-021-00507-y] [Citation(s) in RCA: 144] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2021] [Indexed: 02/08/2023]
Abstract
Almost 60 years have passed since the initial discovery by Hubel and Wiesel that changes in neuronal activity can elicit developmental rewiring of the central nervous system (CNS). Over this period, we have gained a more comprehensive picture of how both spontaneous neural activity and sensory experience-induced changes in neuronal activity guide CNS circuit development. Here we review activity-dependent synaptic pruning in the mammalian CNS, which we define as the removal of a subset of synapses, while others are maintained, in response to changes in neural activity in the developing nervous system. We discuss the mounting evidence that immune and cell-death molecules are important mechanistic links by which changes in neural activity guide the pruning of specific synapses, emphasizing the role of glial cells in this process. Finally, we discuss how these developmental pruning programmes may go awry in neurodevelopmental disorders of the human CNS, focusing on autism spectrum disorder and schizophrenia. Together, our aim is to give an overview of how the field of activity-dependent pruning research has evolved, led to exciting new questions and guided the identification of new, therapeutically relevant mechanisms that result in aberrant circuit development in neurodevelopmental disorders.
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Affiliation(s)
- Travis E Faust
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | - Georgia Gunner
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | - Dorothy P Schafer
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA, USA.
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23
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Albarran E, Raissi A, Jáidar O, Shatz CJ, Ding JB. Enhancing motor learning by increasing the stability of newly formed dendritic spines in the motor cortex. Neuron 2021; 109:3298-3311.e4. [PMID: 34437845 DOI: 10.1016/j.neuron.2021.07.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 07/10/2021] [Accepted: 07/30/2021] [Indexed: 12/18/2022]
Abstract
Dendritic spine dynamics are thought to be substrates for motor learning and memory, and altered spine dynamics often lead to impaired performance. Here, we describe an exception to this rule by studying mice lacking paired immunoglobulin receptor B (PirB-/-). Pyramidal neuron dendrites in PirB-/- mice have increased spine formation rates and density. Surprisingly, PirB-/- mice learn a skilled reaching task faster than wild-type (WT) littermates. Furthermore, stabilization of learning-induced spines is elevated in PirB-/- mice. Mechanistically, single-spine uncaging experiments suggest that PirB is required for NMDA receptor (NMDAR)-dependent spine shrinkage. The degree of survival of newly formed spines correlates with performance, suggesting that increased spine stability is advantageous for learning. Acute inhibition of PirB function in M1 of adult WT mice increases the survival of learning-induced spines and enhances motor learning. These results demonstrate that there are limits on motor learning that can be lifted by manipulating PirB, even in adulthood.
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Affiliation(s)
- Eddy Albarran
- Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Aram Raissi
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Omar Jáidar
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Carla J Shatz
- Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Neurobiology, Stanford University, Stanford, CA 94305, USA; Stanford Bio-X, Stanford University, Stanford, CA 94305, USA.
| | - Jun B Ding
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA; Stanford Bio-X, Stanford University, Stanford, CA 94305, USA.
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24
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Zhang ZH, Chen C, Jia SZ, Cao XC, Liu M, Tian J, Hoffmann PR, Xu HX, Ni JZ, Song GL. Selenium Restores Synaptic Deficits by Modulating NMDA Receptors and Selenoprotein K in an Alzheimer's Disease Model. Antioxid Redox Signal 2021; 35:863-884. [PMID: 32475153 DOI: 10.1089/ars.2019.7990] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Aims: Strong evidence has implicated synaptic failure as a direct contributor to cognitive decline in Alzheimer's disease (AD), and selenium (Se) supplementation has demonstrated potential for AD treatment. However, the exact roles of Se and related selenoproteins in mitigating synaptic deficits remain unclear. Results: Our data show that selenomethionine (Se-Met), as the major organic form of Se in vivo, structurally restored synapses, dendrites, and spines, leading to improved synaptic plasticity and cognitive function in triple transgenic AD (3 × Tg-AD) mice. Furthermore, we found that Se-Met ameliorated synaptic deficits by inhibiting extrasynaptic N-methyl-d-aspartate acid receptors (NMDARs) and stimulating synaptic NMDARs, thereby modulating calcium ion (Ca2+) influx. We observed that a decrease in selenoprotein K (SELENOK) levels was closely related to AD, and a similar disequilibrium was found between synaptic and extrasynaptic NMDARs in SELENOK knockout mice and AD mice. Se-Met treatment upregulated SELENOK levels and restored the balance between synaptic and extrasynaptic NMDAR expression in AD mice. Innovation: These findings establish a key signaling pathway linking SELENOK and NMDARs with synaptic plasticity regulated by Se-Met, and thereby provide insight into mechanisms by which Se compounds mediate synaptic deficits in AD. Conclusion: Our study demonstrates that Se-Met restores synaptic deficits through modulating Ca2+ influx mediated by synaptic and extrasynaptic NMDARs in 3 × Tg-AD mice, and suggests a potentially functional interaction between SELENOK and NMDARs. Antioxid. Redox Signal. 35, 863-884.
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Affiliation(s)
- Zhong-Hao Zhang
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.,Shenzhen Bay Laboratory, Shenzhen, China.,Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Chen Chen
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Shi-Zheng Jia
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Xian-Chun Cao
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Min Liu
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Jing Tian
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Peter R Hoffmann
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Hua-Xi Xu
- Neuroscience Initiative, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Jia-Zuan Ni
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Guo-Li Song
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.,Shenzhen Bay Laboratory, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
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25
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Walker CK, Herskowitz JH. Dendritic Spines: Mediators of Cognitive Resilience in Aging and Alzheimer's Disease. Neuroscientist 2021; 27:487-505. [PMID: 32812494 PMCID: PMC8130863 DOI: 10.1177/1073858420945964] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cognitive resilience is often defined as the ability to remain cognitively normal in the face of insults to the brain. These insults can include disease pathology, such as plaques and tangles associated with Alzheimer's disease, stroke, traumatic brain injury, or other lesions. Factors such as physical or mental activity and genetics may contribute to cognitive resilience, but the neurobiological underpinnings remain ill-defined. Emerging evidence suggests that dendritic spine structural plasticity is one plausible mechanism. In this review, we highlight the basic structure and function of dendritic spines and discuss how spine density and morphology change in aging and Alzheimer's disease. We note evidence that spine plasticity mediates resilience to stress, and we tackle dendritic spines in the context of cognitive resilience to Alzheimer's disease. Finally, we examine how lifestyle and genetic factors may influence dendritic spine plasticity to promote cognitive resilience before discussing evidence for actin regulatory kinases as therapeutic targets for Alzheimer's disease.
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Affiliation(s)
- Courtney K. Walker
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, University of Alabama at Birmingham, USA
| | - Jeremy H. Herskowitz
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, University of Alabama at Birmingham, USA
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26
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Zeiss CJ. Comparative Milestones in Rodent and Human Postnatal Central Nervous System Development. Toxicol Pathol 2021; 49:1368-1373. [PMID: 34569375 DOI: 10.1177/01926233211046933] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Within the substantially different time scales characterizing human and rodent brain development, key developmental processes are remarkably preserved. Shared processes include neurogenesis, myelination, synaptogenesis, and neuronal and synaptic pruning. In general, altricial rodents experience greater central nervous system (CNS) immaturity at birth and accelerated postnatal development compared to humans, in which protracted development of certain processes such as neocortical myelination and synaptic maturation extend into adulthood. Within this generalization, differences in developmental rates of various structures must be understood to accurately model human neurodevelopmental toxicity in rodents. Examples include greater postnatal neurogenesis in rodents, particularly within the dentate gyrus of rats, ongoing generation of neurons in the rodent olfactory bulb, differing time lines of neurotransmitter maturation, and differing time lines of cerebellar development. Comparisons are made to the precocial guinea pig and the long-lived naked mole rat, which, like primates, experiences more advanced CNS development at birth, with more protracted postnatal development. Methods to study various developmental processes are summarized using examples of comparative postnatal injury in humans and rodents.
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Affiliation(s)
- Caroline J Zeiss
- Department of Comparative Medicine, 12228Yale University School of Medicine, New Haven, CT, USA
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27
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Osborne BF, Beamish SB, Schwarz JM. The effects of early-life immune activation on microglia-mediated neuronal remodeling and the associated ontogeny of hippocampal-dependent learning in juvenile rats. Brain Behav Immun 2021; 96:239-255. [PMID: 34126173 PMCID: PMC8319153 DOI: 10.1016/j.bbi.2021.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/11/2021] [Accepted: 06/07/2021] [Indexed: 10/21/2022] Open
Abstract
Many neurodevelopmental disorders and associated learning deficits have been linked to early-life immune activation or ongoing immune dysregulation (Laskaris et al., 2016; O'Connor et al., 2014; Frick et al., 2013). Neuroscientists have begun to understand how the maturation of neural circuits allows for the emergence of cognitive and learning behaviors; yet we know very little about how these developing neural circuits are perturbed by certain events, including risk-factors such as early-life immune activation and immune dysregulation. To answer these questions, we examined the impact of early-life immune activation on the emergence of hippocampal-dependent learning in juvenile male and female rats using a well-characterized hippocampal-dependent learning task and we investigated the corresponding, dynamic multicellular interactions in the hippocampus that may contribute to these learning deficits. We found that even low levels of immune activation can result in hippocampal-depedent learning deficits days later, but only when this activation occurs during a sensitive period of development. The initial immune response and associated cytokine production in the hippocampus resolved within 24 h, several days prior to the observed learning deficit, but notably the initial immune response was followed by altered microglial-neuronal communication and synapse remodeling that changed the structure of hippocampal neurons during this period of juvenile brain development. We conclude that immune activation or dysregulation during a sensitive period of hippocampal development can precipitate the emergence of learning deficits via a multi-cellular process that may be initiated by, but not the direct result of the initial cytokine response. SIGNIFICANCE STATEMENT: Many neurodevelopmental disorders have been linked to early-life immune activation or immune dysregulation; however, very little is known about how dynamic changes in neuroimmune cells mediate the transition from normal brain function to the early stages of cognitive disorders, or how changes in immune signaling are subsequently integrated into developing neuronal networks. The current experiments examined the consequences of immune activation on the cellular and molecular changes that accompany the emergence of learning deficits during a sensitive period of hippocampal development. These findings have the potential to significantly advance our understanding of how early-life immune activation or dysregulation can result in the emergence of cognitive and learning deficits that are the largest source of years lived with disability in humans.
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Affiliation(s)
- Brittany F. Osborne
- University of Delaware, Department of Psychological & Brain Sciences, 108 Wolf Hall, Newark, DE, 19716, USA
| | - Sarah B. Beamish
- University of Delaware, Department of Psychological & Brain Sciences, 108 Wolf Hall, Newark, DE, 19716, USA
| | - Jaclyn M. Schwarz
- University of Delaware, Department of Psychological & Brain Sciences, 108 Wolf Hall, Newark, DE, 19716, USA
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28
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Yong HJ, Hwang JI, Seong JY. Alterations in Dendritic Spine Maturation and Neurite Development Mediated by FAM19A1. Cells 2021; 10:1868. [PMID: 34440636 PMCID: PMC8392516 DOI: 10.3390/cells10081868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 07/20/2021] [Accepted: 07/21/2021] [Indexed: 11/16/2022] Open
Abstract
Neurogenesis and functional brain activity require complex associations of inherently programmed secretory elements that are regulated precisely and temporally. Family with sequence similarity 19 A1 (FAM19A1) is a secreted protein primarily expressed in subsets of terminally differentiated neuronal precursor cells and fully mature neurons in specific brain substructures. Several recent studies have demonstrated the importance of FAM19A1 in brain physiology; however, additional information is needed to support its role in neuronal maturation and function. In this study, dendritic spine morphology in Fam19a1-ablated mice and neurite development during in vitro neurogenesis were examined to understand the putative role of FAM19A1 in neural integrity. Adult Fam19a1-deficient mice showed low dendritic spine density and maturity with reduced dendrite complexity compared to wild-type (WT) littermates. To further explore the effect of FAM19A1 on neuronal maturation, the neurite outgrowth pattern in primary neurons was analyzed in vitro with and without FAM19A1. In response to FAM19A1, WT primary neurons showed reduced neurite complexity, whereas Fam19a1-decifient primary neurons exhibited increased neurite arborization, which was reversed by supplementation with recombinant FAM19A1. Together, these findings suggest that FAM19A1 participates in dendritic spine development and neurite arborization.
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Affiliation(s)
- Hyo-Jeong Yong
- The GPCR Laboratory, Graduate School of Biomedical Science, Korea University College of Medicine, Seoul 02841, Korea;
| | - Jong-Ik Hwang
- The GPCR Laboratory, Graduate School of Biomedical Science, Korea University College of Medicine, Seoul 02841, Korea;
| | - Jae-Young Seong
- The GPCR Laboratory, Graduate School of Biomedical Science, Korea University College of Medicine, Seoul 02841, Korea;
- Division of Research, Neuracle Science Co., Ltd., Seoul 02841, Korea
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29
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Liu T, Lu J, Lukasiewicz K, Pan B, Zuo Y. Stress induces microglia-associated synaptic circuit alterations in the dorsomedial prefrontal cortex. Neurobiol Stress 2021; 15:100342. [PMID: 34136592 PMCID: PMC8182072 DOI: 10.1016/j.ynstr.2021.100342] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/01/2021] [Accepted: 05/12/2021] [Indexed: 01/15/2023] Open
Abstract
The mammalian dorsomedial prefrontal cortex (dmPFC) receives diverse inputs and plays important roles in adaptive behavior and cognitive flexibility. Stress, a major risk factor for many psychiatric disorders, compromises the structure and function of multiple brain regions and circuits. Here we show that 7-day restraint stress impairs reversal learning in the 4-choice odor discrimination test, a decision-making task requiring an intact dmPFC. In vivo two-photon imaging further reveals that stress increases dmPFC dendritic spine elimination, particularly those of the mushroom morphology, without affecting spine formation. In addition, stress alters dmPFC microglial branching complexity and elevates their terminal process dynamics. In stressed mice, dmPFC microglia contact dendrites more frequently, and dendritic spines with microglial contact are prone to elimination. In summary, our work suggests that stress-induced changes in glial-synapse interaction contributes to synaptic loss in dmPFC, resulting in neuronal circuit deficits and impaired cognitive flexibility. Restraint stress impairs cognitive flexibility in adolescent mice. Stress leads to synapse loss on pyramidal neurons in the dorsomedial prefrontal cortex. Stress decreases microglial complexity but increases their terminal dynamics and contacts with dendritic spines. Dendritic spines contacted by microglial processes are more prone to elimination.
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Affiliation(s)
- Taohui Liu
- School of Life Science, Nanchang University, Nanchang, Jiangxi, 330031, China.,Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Ju Lu
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Kacper Lukasiewicz
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Bingxing Pan
- School of Life Science, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
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30
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Cramer SW, Carter RE, Aronson JD, Kodandaramaiah SB, Ebner TJ, Chen CC. Through the looking glass: A review of cranial window technology for optical access to the brain. J Neurosci Methods 2021; 354:109100. [PMID: 33600850 PMCID: PMC8100903 DOI: 10.1016/j.jneumeth.2021.109100] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 02/07/2021] [Accepted: 02/09/2021] [Indexed: 02/07/2023]
Abstract
Deciphering neurologic function is a daunting task, requiring understanding the neuronal networks and emergent properties that arise from the interactions among single neurons. Mechanistic insights into neuronal networks require tools that simultaneously assess both single neuron activity and the consequent mesoscale output. The development of cranial window technologies, in which the skull is thinned or replaced with a synthetic optical interface, has enabled monitoring neuronal activity from subcellular to mesoscale resolution in awake, behaving animals when coupled with advanced microscopy techniques. Here we review recent achievements in cranial window technologies, appraise the relative merits of each design and discuss the future research in cranial window design.
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Affiliation(s)
- Samuel W Cramer
- Department of Neurosurgery, University of Minnesota, 420 Delaware St SE, Mayo D429, MMC 96, Twin Cities, Minneapolis, MN, 55455, USA
| | - Russell E Carter
- Department of Neuroscience, University of Minnesota, Twin Cities, Room 421, 2001 Sixth Street S.E., Minneapolis, MN, 55455 MN, USA
| | - Justin D Aronson
- Department of Neuroscience, University of Minnesota, Twin Cities, Room 421, 2001 Sixth Street S.E., Minneapolis, MN, 55455 MN, USA
| | - Suhasa B Kodandaramaiah
- Department of Mechanical Engineering, University of Minnesota, Twin Cities, MN, USA; Department of Biomedical Engineering, University of Minnesota, Twin Cities, MN, USA; Graduate Program in Neuroscience, University of Minnesota, Twin Cities, MN, USA
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Twin Cities, Room 421, 2001 Sixth Street S.E., Minneapolis, MN, 55455 MN, USA.
| | - Clark C Chen
- Department of Neurosurgery, University of Minnesota, 420 Delaware St SE, Mayo D429, MMC 96, Twin Cities, Minneapolis, MN, 55455, USA.
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31
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Pérez-Villegas EM, Pérez-Rodríguez M, Negrete-Díaz JV, Ruiz R, Rosa JL, de Toledo GA, Rodríguez-Moreno A, Armengol JA. HERC1 Ubiquitin Ligase Is Required for Hippocampal Learning and Memory. Front Neuroanat 2020; 14:592797. [PMID: 33328904 PMCID: PMC7710975 DOI: 10.3389/fnana.2020.592797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 10/23/2020] [Indexed: 11/23/2022] Open
Abstract
Mutations in the human HERC1 E3 ubiquitin ligase protein develop intellectual disability. The tambaleante (tbl) mouse carries a HERC1 mutation characterized by cerebellar ataxia due of adult cerebellar Purkinje cells death by extensive autophagy. Our previous studies demonstrated that both the neuromuscular junction and the peripheral nerve myelin sheaths are also affected in this mutant. Moreover, there are signs of dysregulated autophagy in the central nervous system in the tbl mouse, affecting spinal cord motor neurons, and pyramidal neurons of the neocortex and the hippocampal CA3 region. The tbl mutation affects associative learning, with absence of short- and long-term potentiation in the lateral amygdala, altered spinogenesis in their neurons, and a dramatic decrease in their glutamatergic input. To assess whether other brain areas engaged in learning processes might be affected by the tbl mutation, we have studied the tbl hippocampus using behavioral tests, ex vivo electrophysiological recordings, immunohistochemistry, the Golgi-Cox method and transmission electron microscopy. The tbl mice performed poorly in the novel-object recognition, T-maze and Morris water maze tests. In addition, there was a decrease in glutamatergic input while the GABAergic one remains unaltered in the hippocampal CA1 region of tbl mice, accompanied by changes in the dendritic spines, and signs of cellular damage. Moreover, the proportions of immature and mature neurons in the dentate gyrus of the tbl hippocampus differ relative to the control mice. Together, these observations demonstrate the important role of HERC1 in regulating synaptic activity during learning.
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Affiliation(s)
- Eva M. Pérez-Villegas
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Seville, Spain
| | - Mikel Pérez-Rodríguez
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Seville, Spain
| | - José V. Negrete-Díaz
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Seville, Spain
- División de Ciencias de la Salud e Ingenierías, Universidad de Guanajuato, Guanajuato, Mexico
| | - Rocío Ruiz
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Seville, Seville, Spain
- Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
| | - Jose Luis Rosa
- Departament de Ciències Fisiològiques, IBIDELL, Universitat de Barcelona, Barcelona, Spain
| | | | - Antonio Rodríguez-Moreno
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Seville, Spain
| | - José A. Armengol
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Seville, Spain
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32
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García-Serra A, Radosevic M, Pupak A, Brito V, Ríos J, Aguilar E, Maudes E, Ariño H, Spatola M, Mannara F, Pedreño M, Joubert B, Ginés S, Planagumà J, Dalmau J. Placental transfer of NMDAR antibodies causes reversible alterations in mice. NEUROLOGY-NEUROIMMUNOLOGY & NEUROINFLAMMATION 2020; 8:8/1/e915. [PMID: 33172961 PMCID: PMC7713722 DOI: 10.1212/nxi.0000000000000915] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 08/26/2020] [Indexed: 01/10/2023]
Abstract
Objective To determine whether maternofetal transfer of NMDA receptor (NMDAR) antibodies has pathogenic effects on the fetus and offspring, we developed a model of placental transfer of antibodies. Methods Pregnant C57BL/6J mice were administered via tail vein patients' or controls' immunoglobulin G (IgG) on days 14–16 of gestation, when the placenta is able to transport IgG and the immature fetal blood-brain barrier is less restrictive to IgG crossing. Immunohistochemical and DiOlistic (gene gun delivery of fluorescent dye) staining, confocal microscopy, standardized developmental and behavioral tasks, and hippocampal long-term potentiation were used to determine the antibody effects. Results In brains of fetuses, patients' IgG, but not controls' IgG, bound to NMDAR, causing a decrease in NMDAR clusters and cortical plate thickness. No increase in neonatal mortality was observed, but offspring exposed in utero to patients' IgG had reduced levels of cell-surface and synaptic NMDAR, increased dendritic arborization, decreased density of mature (mushroom-shaped) spines, microglial activation, and thinning of brain cortical layers II–IV with cellular compaction. These animals also had a delay in innate reflexes and eye opening and during follow-up showed depressive-like behavior, deficits in nest building, poor motor coordination, and impaired social-spatial memory and hippocampal plasticity. Remarkably, all these paradigms progressively improved (becoming similar to those of controls) during follow-up until adulthood. Conclusions In this model, placental transfer of patients' NMDAR antibodies caused severe but reversible synaptic and neurodevelopmental alterations. Reversible antibody effects may contribute to the infrequent and limited number of complications described in children of patients who develop anti-NMDAR encephalitis during pregnancy.
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Affiliation(s)
- Anna García-Serra
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Marija Radosevic
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Anika Pupak
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Veronica Brito
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - José Ríos
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Esther Aguilar
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Estibaliz Maudes
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Helena Ariño
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Marianna Spatola
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Francesco Mannara
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Marta Pedreño
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Bastien Joubert
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Silvia Ginés
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Jesús Planagumà
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain
| | - Josep Dalmau
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (A.G.-S., M.R., A.P., V.B., E.A., E.M., H.A., M.S., F.M., M.P., B.J., S.G., J.P., J.D.), Hospital Clínic, Universitat de Barcelona; Departament de Biomedicina (A.P., V.B., S.G.), Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) (A.P., V.B., S.G.), Madrid; Medical Statistics Core Facility (J.R.), IDIBAPS and Hospital Clínic, Barcelona; Biostatistics Unit (J.R.), School of Medicine, Universitat Autònoma de Barcelona; Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER) (J.D.), Madrid, Spain; Department of Neurology (J.D.), University of Pennsylvania, Philadelphia; and Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain.
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Tomorsky J, Parker PRL, Doe CQ, Niell CM. Precise levels of nectin-3 are required for proper synapse formation in postnatal visual cortex. Neural Dev 2020; 15:13. [PMID: 33160402 PMCID: PMC7648993 DOI: 10.1186/s13064-020-00150-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/22/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Developing cortical neurons express a tightly choreographed sequence of cytoskeletal and transmembrane proteins to form and strengthen specific synaptic connections during circuit formation. Nectin-3 is a cell-adhesion molecule with previously described roles in synapse formation and maintenance. This protein and its binding partner, nectin-1, are selectively expressed in upper-layer neurons of mouse visual cortex, but their role in the development of cortical circuits is unknown. METHODS Here we block nectin-3 expression (via shRNA) or overexpress nectin-3 in developing layer 2/3 visual cortical neurons using in utero electroporation. We then assay dendritic spine densities at three developmental time points: eye opening (postnatal day (P)14), one week following eye opening after a period of heightened synaptogenesis (P21), and at the close of the critical period for ocular dominance plasticity (P35). RESULTS Knockdown of nectin-3 beginning at E15.5 or ~ P19 increased dendritic spine densities at P21 or P35, respectively. Conversely, overexpressing full length nectin-3 at E15.5 decreased dendritic spine densities when all ages were considered together. The effects of nectin-3 knockdown and overexpression on dendritic spine densities were most significant on proximal secondary apical dendrites. Interestingly, an even greater decrease in dendritic spine densities, particularly on basal dendrites at P21, was observed when we overexpressed nectin-3 lacking its afadin binding domain. CONCLUSION These data collectively suggest that the proper levels and functioning of nectin-3 facilitate normal synapse formation after eye opening on apical and basal dendrites in layer 2/3 of visual cortex.
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Affiliation(s)
- Johanna Tomorsky
- Institute of Neuroscience, University of Oregon, Eugene, OR, 97403, USA.
- Department of Biology, University of Oregon, Eugene, OR, 97403, USA.
- Stanford University, 318 Campus Drive, Stanford, CA, 94305, USA.
| | - Philip R L Parker
- Institute of Neuroscience, University of Oregon, Eugene, OR, 97403, USA
- Department of Biology, University of Oregon, Eugene, OR, 97403, USA
| | - Chris Q Doe
- Institute of Neuroscience, University of Oregon, Eugene, OR, 97403, USA
- Department of Biology, University of Oregon, Eugene, OR, 97403, USA
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97403, USA
- Howard Hughes Medical Institute, University of Oregon, Eugene, OR, 97403, USA
| | - Cristopher M Niell
- Institute of Neuroscience, University of Oregon, Eugene, OR, 97403, USA.
- Department of Biology, University of Oregon, Eugene, OR, 97403, USA.
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Iwasato T. In vivo imaging of neural circuit formation in the neonatal mouse barrel cortex. Dev Growth Differ 2020; 62:476-486. [DOI: 10.1111/dgd.12693] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/13/2020] [Accepted: 09/27/2020] [Indexed: 01/21/2023]
Affiliation(s)
- Takuji Iwasato
- Laboratory of Mammalian Neural Circuits National Institute of Genetics Mishima Japan
- Department of Genetics SOKENDAI Mishima Japan
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Ma X, Chen K, Cui Y, Huang G, Nehme A, Zhang L, Li H, Wei J, Liong K, Liu Q, Shi L, Wu J, Qiu S. Depletion of microglia in developing cortical circuits reveals its critical role in glutamatergic synapse development, functional connectivity, and critical period plasticity. J Neurosci Res 2020; 98:1968-1986. [PMID: 32594561 DOI: 10.1002/jnr.24641] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/23/2020] [Accepted: 04/25/2020] [Indexed: 02/05/2023]
Abstract
Microglia populate the early developing brain and mediate pruning of the central synapses. Yet, little is known on their functional significance in shaping the developing cortical circuits. We hypothesize that the developing cortical circuits require microglia for proper circuit maturation and connectivity, and as such, ablation of microglia during the cortical critical period may result in a long-lasting circuit abnormality. We administered PLX3397, a colony-stimulating factor 1 receptor inhibitor, to mice starting at postnatal day 14 and through P28, which depletes >75% of microglia in the visual cortex (VC). This treatment largely covers the critical period (P19-32) of VC maturation and plasticity. Patch clamp recording in VC layer 2/3 (L2/3) and L5 neurons revealed increased mEPSC frequency and reduced amplitude, and decreased AMPA/NMDA current ratio, indicative of altered synapse maturation. Increased spine density was observed in these neurons, potentially reflecting impaired synapse pruning. In addition, VC intracortical circuit functional connectivity, assessed by laser scanning photostimulation combined with glutamate uncaging, was dramatically altered. Using two photon longitudinal dendritic spine imaging, we confirmed that spine elimination/pruning was diminished during VC critical period when microglia were depleted. Reduced spine pruning thus may account for increased spine density and disrupted connectivity of VC circuits. Lastly, using single-unit recording combined with monocular deprivation, we found that ocular dominance plasticity in the VC was obliterated during the critical period as a result of microglia depletion. These data establish a critical role of microglia in developmental cortical synapse pruning, maturation, functional connectivity, and critical period plasticity.
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Affiliation(s)
- Xiaokuang Ma
- Department of Pharmacology, Shantou University Medical College, Shantou, China
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Ke Chen
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Yuehua Cui
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Guanqun Huang
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou, China
| | - Antoine Nehme
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Le Zhang
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Handong Li
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Jing Wei
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Katerina Liong
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Qiang Liu
- Barrow Neurological Institute, St. Joseph's Hospital Medical Center, Phoenix, AZ, USA
| | - Lingling Shi
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou, China
| | - Jie Wu
- Department of Pharmacology, Shantou University Medical College, Shantou, China
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
- Barrow Neurological Institute, St. Joseph's Hospital Medical Center, Phoenix, AZ, USA
| | - Shenfeng Qiu
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
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REM sleep promotes experience-dependent dendritic spine elimination in the mouse cortex. Nat Commun 2020; 11:4819. [PMID: 32968048 PMCID: PMC7511313 DOI: 10.1038/s41467-020-18592-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 08/26/2020] [Indexed: 01/10/2023] Open
Abstract
In many parts of the nervous system, experience-dependent refinement of neuronal circuits predominantly involves synapse elimination. The role of sleep in this process remains unknown. We investigated the role of sleep in experience-dependent dendritic spine elimination of layer 5 pyramidal neurons in the visual (V1) and frontal association cortex (FrA) of 1-month-old mice. We found that monocular deprivation (MD) or auditory-cued fear conditioning (FC) caused rapid spine elimination in V1 or FrA, respectively. MD- or FC-induced spine elimination was significantly reduced after total sleep or REM sleep deprivation. Total sleep or REM sleep deprivation also prevented MD- and FC-induced reduction of neuronal activity in response to visual or conditioned auditory stimuli. Furthermore, dendritic calcium spikes increased substantially during REM sleep, and the blockade of these calcium spikes prevented MD- and FC-induced spine elimination. These findings reveal an important role of REM sleep in experience-dependent synapse elimination and neuronal activity reduction. Sleep plays an important role in learning and memory. Here the authors show that experience dependent elimination of spines is attenuated by REM sleep deprivation.
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Runge K, Cardoso C, de Chevigny A. Dendritic Spine Plasticity: Function and Mechanisms. Front Synaptic Neurosci 2020. [DOI: 10.3389/fnsyn.2020.00036
expr 823669561 + 872784217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
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Runge K, Cardoso C, de Chevigny A. Dendritic Spine Plasticity: Function and Mechanisms. Front Synaptic Neurosci 2020; 12:36. [PMID: 32982715 PMCID: PMC7484486 DOI: 10.3389/fnsyn.2020.00036] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/28/2020] [Indexed: 12/12/2022] Open
Abstract
Dendritic spines are small protrusions studding neuronal dendrites, first described in 1888 by Ramón y Cajal using his famous Golgi stainings. Around 50 years later the advance of electron microscopy (EM) confirmed Cajal's intuition that spines constitute the postsynaptic site of most excitatory synapses in the mammalian brain. The finding that spine density decreases between young and adult ages in fixed tissues suggested that spines are dynamic. It is only a decade ago that two-photon microscopy (TPM) has unambiguously proven the dynamic nature of spines, through the repeated imaging of single spines in live animals. Spine dynamics comprise formation, disappearance, and stabilization of spines and are modulated by neuronal activity and developmental age. Here, we review several emerging concepts in the field that start to answer the following key questions: What are the external signals triggering spine dynamics and the molecular mechanisms involved? What is, in return, the role of spine dynamics in circuit-rewiring, learning, and neuropsychiatric disorders?
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Affiliation(s)
- Karen Runge
- Institut de Neurobiologie de la Méditerranée (INMED) INSERM U1249, Aix-Marseille University, Marseille, France
| | - Carlos Cardoso
- Institut de Neurobiologie de la Méditerranée (INMED) INSERM U1249, Aix-Marseille University, Marseille, France
| | - Antoine de Chevigny
- Institut de Neurobiologie de la Méditerranée (INMED) INSERM U1249, Aix-Marseille University, Marseille, France
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Brain regions vulnerable and resistant to aging without Alzheimer's disease. PLoS One 2020; 15:e0234255. [PMID: 32726311 PMCID: PMC7390259 DOI: 10.1371/journal.pone.0234255] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/21/2020] [Indexed: 11/19/2022] Open
Abstract
'Normal aging' in the brain refers to age-related changes that occur independent of disease, in particular Alzheimer's disease. A major barrier to mapping normal brain aging has been the difficulty in excluding the earliest preclinical stages of Alzheimer's disease. Here, before addressing this issue we first imaged a mouse model and learn that the best MRI measure of dendritic spine loss, a known pathophysiological driver of normal aging, is one that relies on the combined use of functional and structural MRI. In the primary study, we then deployed the combined functional-structural MRI measure to investigate over 100 cognitively-normal people from 20-72 years of age. Next, to cover the tail end of aging, in secondary analyses we investigated structural MRI acquired from cognitively-normal people, 60-84 years of age, who were Alzheimer's-free via biomarkers. Collectively, the results from the primary functional-structural study, and the secondary structural studies revealed that the dentate gyrus is a hippocampal region differentially affected by aging, and that the entorhinal cortex is a region most resistant to aging. Across the cortex, the primary functional-structural study revealed and that the inferior frontal gyrus is differentially affected by aging, however, the secondary structural studies implicated other frontal cortex regions. Together, the results clarify how normal aging may affect the brain and has possible mechanistic and therapeutic implications.
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Dendritic Spine Dynamics after Peripheral Nerve Injury: An Intravital Structural Study. J Neurosci 2020; 40:4297-4308. [PMID: 32371602 DOI: 10.1523/jneurosci.2858-19.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 02/10/2020] [Accepted: 02/28/2020] [Indexed: 11/21/2022] Open
Abstract
Neuropathic pain is an intractable medical condition with few or no options for effective treatment. Emerging evidence shows a strong structure-function relationship between dendritic spine dysgenesis and the presence of neuropathic pain. Postmortem tissue analyses can only imply dynamic structural changes associated with injury-induced pain. Here, we profiled the in vivo dynamics of dendritic spines over time on the same superficial dorsal horn (lamina II) neurons before and after peripheral nerve injury-induced pain. We used a two-photon, whole-animal imaging paradigm that permitted repeat imaging of the same dendritic branches of these neurons in C57/Bl6 Thy1-YFP male mice. Our study demonstrates, for the first time, the ongoing, steady-state changes in dendritic spine dynamics in the dorsal horn associated with peripheral nerve injury and pain. Ultimately, the relationship between altered dendritic spine dynamics and neuropathic pain may serve as a structure-based opportunity to investigate mechanisms of pain following injury and disease.SIGNIFICANCE STATEMENT This work is important because it demonstrates for the first time: (1) the powerful utility of intravital study of dendritic spine dynamics in the superficial dorsal horn; (2) that nerve injury-induced pain triggers changes in dendritic spine steady-state behavior in the spinal cord dorsal horn; and (3) this work opens the door to further investigations in vivo of spinal cord dendritic spine dynamics in the context of injury and disease.
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Cheyne JE, Montgomery JM. The cellular and molecular basis of in vivo synaptic plasticity in rodents. Am J Physiol Cell Physiol 2020; 318:C1264-C1283. [PMID: 32320288 DOI: 10.1152/ajpcell.00416.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Plasticity within the neuronal networks of the brain underlies the ability to learn and retain new information. The initial discovery of synaptic plasticity occurred by measuring synaptic strength in vivo, applying external stimulation and observing an increase in synaptic strength termed long-term potentiation (LTP). Many of the molecular pathways involved in LTP and other forms of synaptic plasticity were subsequently uncovered in vitro. Over the last few decades, technological advances in recording and imaging in live animals have seen many of these molecular mechanisms confirmed in vivo, including structural changes both pre- and postsynaptically, changes in synaptic strength, and changes in neuronal excitability. A well-studied aspect of neuronal plasticity is the capacity of the brain to adapt to its environment, gained by comparing the brains of deprived and experienced animals in vivo, and in direct response to sensory stimuli. Multiple in vivo studies have also strongly linked plastic changes to memory by interfering with the expression of plasticity and by manipulating memory engrams. Plasticity in vivo also occurs in the absence of any form of external stimulation, i.e., during spontaneous network activity occurring with brain development. However, there is still much to learn about how plasticity is induced during natural learning and how this is altered in neurological disorders.
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Affiliation(s)
- Juliette E Cheyne
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
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Cirelli C, Tononi G. Effects of sleep and waking on the synaptic ultrastructure. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190235. [PMID: 32248785 PMCID: PMC7209920 DOI: 10.1098/rstb.2019.0235] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We summarize here several studies performed in our laboratory, mainly using serial block-face scanning electron microscopy (SBEM), to assess how sleep, spontaneous waking and short sleep deprivation affect the size and number of synapses in the cerebral cortex and hippocampus. With SBEM, we reconstructed thousands of cortical and hippocampal excitatory, axospinous synapses and compared the distribution of their size after several hours of sleep relative to several hours of waking. Because stronger synapses are on average also bigger, the goal was to test a prediction of the synaptic homeostasis hypothesis, according to which overall synaptic strength increases during waking, owing to ongoing learning, and needs to be renormalized during sleep, to avoid saturation and to benefit memory consolidation and integration. Consistent with this hypothesis, we found that the size of the axon–spine interface (ASI), a morphological measure of synaptic strength, was on average smaller after sleep, but with interesting differences between primary cortex and the CA1 region of the hippocampus. In two-week-old mouse pups, the decline in ASI size after sleep was larger, and affected more cortical synapses, compared with one-month-old adolescent mice, suggesting that synaptic renormalization during sleep may be especially important during early development. This work is still in progress and other brain areas need to be tested after sleep, acute sleep loss and chronic sleep restriction. Still, the current results show that a few hours of sleep or waking lead to significant changes in synaptic morphology that can be linked to changes in synaptic efficacy. This article is part of the Theo Murphy meeting issue ‘Memory reactivation: replaying events past, present and future’.
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Affiliation(s)
- Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Blvd, Madison, WI 53719, USA
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Blvd, Madison, WI 53719, USA
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43
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Seaton G, Hodges G, de Haan A, Grewal A, Pandey A, Kasai H, Fox K. Dual-Component Structural Plasticity Mediated by αCaMKII Autophosphorylation on Basal Dendrites of Cortical Layer 2/3 Neurones. J Neurosci 2020; 40:2228-2245. [PMID: 32001612 PMCID: PMC7083283 DOI: 10.1523/jneurosci.2297-19.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/30/2019] [Accepted: 01/03/2020] [Indexed: 11/21/2022] Open
Abstract
Sensory cortex exhibits receptive field plasticity throughout life in response to changes in sensory experience and offers the experimental possibility of aligning functional changes in receptive field properties with underpinning structural changes in synapses. We looked at the effects on structural plasticity of two different patterns of whisker deprivation in male and female mice: chessboard deprivation, which causes functional plasticity; and all deprived, which does not. Using 2-photon microscopy and chronic imaging through a cranial window over the barrel cortex, we found that layer 2/3 neurones exhibit robust structural plasticity, but only in response to whisker deprivation patterns that cause functional plasticity. Chessboard pattern deprivation caused dual-component plasticity in layer 2/3 by (1) increasing production of new spines that subsequently persisted for weeks and (2) enlarging spine head sizes in the preexisting stable spine population. Structural plasticity occurred on basal dendrites, but not apical dendrites. Both components of plasticity were absent in αCaMKII-T286A mutants that lack LTP and experience-dependent potentiation in barrel cortex, implying that αCaMKII autophosphorylation is not only important for stabilization and enlargement of spines, but also for new spine production. These studies therefore reveal the relationship between spared whisker potentiation in layer 2/3 neurones and the form and mechanisms of structural plasticity processes that underlie them.SIGNIFICANCE STATEMENT This study provides a missing link in a chain of reasoning that connects LTP to experience-dependent functional plasticity in vivo We found that increases in dendritic spine formation and spine enlargement (both of which are characteristic of LTP) only occurred in barrel cortex during sensory deprivation that produced potentiation of sensory responses. Furthermore, the dendritic spine plasticity did not occur during sensory deprivation in mice lacking LTP and experience-dependent potentiation (αCaMKII autophosphorylation mutants). We also found that the dual-component dendritic spine plasticity only occurred on basal dendrites and not on apical dendrites, thereby resolving a paradox in the literature suggesting that layer 2/3 neurones lack structural plasticity in response to sensory deprivation.
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Affiliation(s)
- Gillian Seaton
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom, and
| | - Gladys Hodges
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom, and
| | - Annelies de Haan
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom, and
| | - Aneesha Grewal
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom, and
| | - Anurag Pandey
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom, and
| | - Haruo Kasai
- Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Kevin Fox
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom, and
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Patwa S, Benson CA, Dyer L, Olson K, Bangalore L, Hill M, Waxman SG, Tan AM. Spinal cord motor neuron plasticity accompanies second-degree burn injury and chronic pain. Physiol Rep 2019; 7:e14288. [PMID: 31858746 PMCID: PMC6923170 DOI: 10.14814/phy2.14288] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Burn injuries and associated complications present a major public health challenge. Many burn patients develop clinically intractable complications, including pain and other sensory disorders. Recent evidence has shown that dendritic spine neuropathology in spinal cord sensory and motor neurons accompanies central nervous system (CNS) or peripheral nervous system (PNS) trauma and disease. However, no research has investigated similar dendritic spine neuropathologies following a cutaneous thermal burn injury. In this retrospective investigation, we analyzed dendritic spine morphology and localization in alpha-motor neurons innervating a burn-injured area of the body (hind paw). To identify a molecular regulator of these dendritic spine changes, we further profiled motor neuron dendritic spines in adult mice treated with romidepsin, a clinically approved Pak1-inhibitor, or vehicle control at two postburn time points: Day 6 immediately after treatment, or Day 10 following drug withdrawal. In control treated mice, we observed an overall increase in dendritic spine density, including structurally mature spines with mushroom-shaped morphology. Pak1-inhibitor treatment reduced injury-induced changes to similar levels observed in animals without burn injury. The effectiveness of the Pak1-inhibitor was durable, since normalized dendritic spine profiles remained as long as 4 days despite drug withdrawal. This study is the first report of evidence demonstrating that a second-degree burn injury significantly affects motor neuron structure within the spinal cord. Furthermore, our results support the opportunity to study dendritic spine dysgenesis as a novel avenue to clarify the complexities of neurological disease following traumatic injury.
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Affiliation(s)
- Siraj Patwa
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
| | - Curtis A. Benson
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
| | - Lauren Dyer
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
| | - Kai‐Lan Olson
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
| | - Lakshmi Bangalore
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
| | - Myriam Hill
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
| | - Stephen G. Waxman
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
| | - Andrew M. Tan
- Department of Neurology and Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenConnecticut
- Rehabilitation Research CenterVeterans Affairs Connecticut Healthcare SystemWest HavenConnecticut
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Palaniyappan L. Inefficient neural system stabilization: a theory of spontaneous resolutions and recurrent relapses in psychosis. J Psychiatry Neurosci 2019; 44:367-383. [PMID: 31245961 PMCID: PMC6821513 DOI: 10.1503/jpn.180038] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 02/07/2019] [Accepted: 03/05/2019] [Indexed: 12/21/2022] Open
Abstract
A striking feature of psychosis is its heterogeneity. Presentations of psychosis vary from transient symptoms with no functional consequence in the general population to a tenacious illness at the other extreme, with a wide range of variable trajectories in between. Even among patients with schizophrenia, who are diagnosed on the basis of persistent deterioration, marked variation is seen in response to treatment, frequency of relapses and degree of eventual recovery. Existing theoretical accounts of psychosis focus almost exclusively on how symptoms are initially formed, with much less emphasis on explaining their variable course. In this review, I present an account that links several existing notions of the biology of psychosis with the variant clinical trajectories. My aim is to incorporate perspectives of systems neuroscience in a staging framework to explain the individual variations in illness course that follow the onset of psychosis.
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Affiliation(s)
- Lena Palaniyappan
- From the Department of Psychiatry and Robarts Research Institute, University of Western Ontario and Lawson Health Research Institute, London, Ont., Canada
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46
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Hinton EA, Li DC, Allen AG, Gourley SL. Social Isolation in Adolescence Disrupts Cortical Development and Goal-Dependent Decision-Making in Adulthood, Despite Social Reintegration. eNeuro 2019; 6:ENEURO.0318-19.2019. [PMID: 31527057 PMCID: PMC6757188 DOI: 10.1523/eneuro.0318-19.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 08/19/2019] [Indexed: 12/18/2022] Open
Abstract
The social environment influences neurodevelopment. Investigations using rodents to study this phenomenon commonly isolate subjects, then assess neurobehavioral consequences while animals are still isolated. This approach precludes one from dissociating the effects of on-going versus prior isolation, hindering our complete understanding of the consequences of social experience during particular developmental periods. Here, we socially isolated adolescent mice from postnatal day (P)31 to P60, then re-housed them into social groups. We tested their ability to select actions based on expected outcomes using multiple reinforcer devaluation and instrumental contingency degradation techniques. Social isolation in adolescence (but not adulthood) weakened instrumental response updating, causing mice to defer to habit-like behaviors. Habit biases were associated with glucocorticoid insufficiency in adolescence, oligodendrocyte marker loss throughout cortico-striatal regions, and dendritic spine and synaptic marker excess in the adult orbitofrontal cortex (OFC). Artificial, chemogenetic stimulation of the ventrolateral OFC in typical, healthy mice recapitulated response biases following isolation, causing habit-like behaviors. Meanwhile, correcting dendritic architecture by inhibiting the cytoskeletal regulatory protein ROCK remedied instrumental response updating defects in socially isolated mice. Our findings suggest that adolescence is a critical period during which social experience optimizes one's ability to seek and attain goals later in life. Age-typical dendritic spine elimination appears to be an essential factor, and in its absence, organisms may defer to habit-based behaviors.
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Affiliation(s)
- Elizabeth A Hinton
- Graduate Program in Neuroscience, Emory University, Atlanta, GA, 30329
- Center for Translational and Social Neuroscience, Emory University, Atlanta, GA, 30329
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329
- Department of Pediatrics, Emory University, Atlanta, GA, 30329
- Department of Psychiatry, Emory University, Atlanta, GA, 30329
| | - Dan C Li
- Graduate Program in Neuroscience, Emory University, Atlanta, GA, 30329
- Center for Translational and Social Neuroscience, Emory University, Atlanta, GA, 30329
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329
- Department of Pediatrics, Emory University, Atlanta, GA, 30329
- Department of Psychiatry, Emory University, Atlanta, GA, 30329
| | - Aylet G Allen
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329
- Department of Pediatrics, Emory University, Atlanta, GA, 30329
| | - Shannon L Gourley
- Graduate Program in Neuroscience, Emory University, Atlanta, GA, 30329
- Center for Translational and Social Neuroscience, Emory University, Atlanta, GA, 30329
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329
- Department of Pediatrics, Emory University, Atlanta, GA, 30329
- Department of Psychiatry, Emory University, Atlanta, GA, 30329
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47
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Xu ZX, Tan JW, Xu H, Hill CJ, Ostrovskaya O, Martemyanov KA, Xu B. Caspase-2 promotes AMPA receptor internalization and cognitive flexibility via mTORC2-AKT-GSK3β signaling. Nat Commun 2019; 10:3622. [PMID: 31399584 PMCID: PMC6689033 DOI: 10.1038/s41467-019-11575-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 07/23/2019] [Indexed: 01/22/2023] Open
Abstract
Caspase-2 is the most evolutionarily conserved member in the caspase family of proteases and is constitutively expressed in most cell types including neurons; however, its physiological function remains largely unknown. Here we report that caspase-2 plays a critical role in synaptic plasticity and cognitive flexibility. We found that caspase-2 deficiency led to deficits in dendritic spine pruning, internalization of AMPA receptors and long-term depression. Our results indicate that caspase-2 degrades Rictor, a key mTOR complex 2 (mTORC2) component, to inhibit Akt activation, which leads to enhancement of the GSK3β activity and thereby long-term depression. Furthermore, we found that mice lacking caspase-2 displayed elevated levels of anxiety, impairment in reversal water maze learning, and little memory loss over time. These results not only uncover a caspase-2-mTORC2-Akt-GSK3β signaling pathway, but also suggest that caspase-2 is important for memory erasing and normal behaviors by regulating synaptic number and transmission.
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Affiliation(s)
- Zhi-Xiang Xu
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, 33458, USA
| | - Ji-Wei Tan
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, 33458, USA
| | - Haifei Xu
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, 33458, USA
| | - Cassandra J Hill
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, 33458, USA
| | - Olga Ostrovskaya
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, 33458, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, 33458, USA
| | - Baoji Xu
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, 33458, USA.
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48
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Ko HG, Choi JH, Park DI, Kang SJ, Lim CS, Sim SE, Shim J, Kim JI, Kim S, Choi TH, Ye S, Lee J, Park P, Kim S, Do J, Park J, Islam MA, Kim HJ, Turck CW, Collingridge GL, Zhuo M, Kaang BK. Rapid Turnover of Cortical NCAM1 Regulates Synaptic Reorganization after Peripheral Nerve Injury. Cell Rep 2019; 22:748-759. [PMID: 29346771 DOI: 10.1016/j.celrep.2017.12.059] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 11/27/2017] [Accepted: 12/17/2017] [Indexed: 11/24/2022] Open
Abstract
Peripheral nerve injury can induce pathological conditions that lead to persistent sensitized nociception. Although there is evidence that plastic changes in the cortex contribute to this process, the underlying molecular mechanisms are unclear. Here, we find that activation of the anterior cingulate cortex (ACC) induced by peripheral nerve injury increases the turnover of specific synaptic proteins in a persistent manner. We demonstrate that neural cell adhesion molecule 1 (NCAM1) is one of the molecules involved and show that it mediates spine reorganization and contributes to the behavioral sensitization. We show striking parallels in the underlying mechanism with the maintenance of NMDA-receptor- and protein-synthesis-dependent long-term potentiation (LTP) in the ACC. Our results, therefore, demonstrate a synaptic mechanism for cortical reorganization and suggest potential avenues for neuropathic pain treatment.
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Affiliation(s)
- Hyoung-Gon Ko
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea; Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Jun-Hyeok Choi
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Dong Ik Park
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Kraepelinstr. 2, 80804 Munich, Germany
| | - SukJae Joshua Kang
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Chae-Seok Lim
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Su-Eon Sim
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Jaehoon Shim
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Ji-Il Kim
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Siyong Kim
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Tae-Hyeok Choi
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Sanghyun Ye
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Jaehyun Lee
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Pojeong Park
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Somi Kim
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Jeehaeh Do
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Jihye Park
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Md Ariful Islam
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea
| | - Hyun Jeong Kim
- Department of Dental Anesthesiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul 03080, South Korea
| | - Christoph W Turck
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Kraepelinstr. 2, 80804 Munich, Germany
| | - Graham L Collingridge
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, UK; Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada.
| | - Min Zhuo
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Bong-Kiun Kaang
- School of Biological Sciences, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, South Korea; Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
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49
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Voglewede RL, Vandemark KM, Davidson AM, DeWitt AR, Heffler MD, Trimmer EH, Mostany R. Reduced sensory-evoked structural plasticity in the aging barrel cortex. Neurobiol Aging 2019; 81:222-233. [PMID: 31323444 DOI: 10.1016/j.neurobiolaging.2019.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 06/15/2019] [Accepted: 06/15/2019] [Indexed: 10/26/2022]
Abstract
Impairments in synaptic connectivity have been linked to cognitive deficits in age-related neurodegenerative disorders and healthy aging. However, the anatomical and structural bases of these impairments have not been identified yet. A hallmark of neural plasticity in young adults is short-term synaptic rearrangement, yet aged animals already display higher synaptic turnover rates at the baseline. Using two-photon excitation (2PE) microscopy, we explored if this elevated turnover alters the aged brain's response to plasticity. Following a sensory-evoked plasticity protocol involving whisker stimulation, aged mice display reduced spine dynamics (gain, loss, and turnover), decreased spine clustering, and lower spine stability when compared to young adult mice. These results suggest a deficiency of the cortical neurons of aged mice to structurally incorporate new sensory experiences, in the form of clustered, long-lasting synapses, into already existing cortical circuits. This research provides the first evidence linking experience-dependent plasticity with in vivo spine dynamics in the aged brain and supports a model of both reduced synaptic plasticity and reduced synaptic tenacity in the aged somatosensory system.
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Affiliation(s)
- Rebecca L Voglewede
- Neuroscience Program, Tulane University School of Science and Engineering, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA; Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA
| | - Kaeli M Vandemark
- Neuroscience Program, Tulane University School of Science and Engineering, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | - Andrew M Davidson
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA; Department of Cell and Molecular Biology, Tulane University School of Science and Engineering, New Orleans, LA, USA
| | - Annie R DeWitt
- Neuroscience Program, Tulane University School of Science and Engineering, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | - Marissa D Heffler
- Neuroscience Program, Tulane University School of Science and Engineering, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA; Department of Biomedical Engineering, Tulane University School of Science and Engineering, Lindy Boggs Center Suite 500, New Orleans, LA, USA
| | - Emma H Trimmer
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA
| | - Ricardo Mostany
- Neuroscience Program, Tulane University School of Science and Engineering, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA; Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA.
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50
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Hill SA, Blaeser AS, Coley AA, Xie Y, Shepard KA, Harwell CC, Gao WJ, Garcia ADR. Sonic hedgehog signaling in astrocytes mediates cell type-specific synaptic organization. eLife 2019; 8:45545. [PMID: 31194676 PMCID: PMC6629371 DOI: 10.7554/elife.45545] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 06/13/2019] [Indexed: 01/08/2023] Open
Abstract
Astrocytes have emerged as integral partners with neurons in regulating synapse formation and function, but the mechanisms that mediate these interactions are not well understood. Here, we show that Sonic hedgehog (Shh) signaling in mature astrocytes is required for establishing structural organization and remodeling of cortical synapses in a cell type-specific manner. In the postnatal cortex, Shh signaling is active in a subpopulation of mature astrocytes localized primarily in deep cortical layers. Selective disruption of Shh signaling in astrocytes produces a dramatic increase in synapse number specifically on layer V apical dendrites that emerges during adolescence and persists into adulthood. Dynamic turnover of dendritic spines is impaired in mutant mice and is accompanied by an increase in neuronal excitability and a reduction of the glial-specific, inward-rectifying K+ channel Kir4.1. These data identify a critical role for Shh signaling in astrocyte-mediated modulation of neuronal activity required for sculpting synapses. A central system of neurons in the spinal cord and brain coordinate most of our body’s actions, ranging from regulating our heart rate to controlling our movement and thoughts. As the brain develops, neurons form specialized contacts with one another known as synapses. If the number of synapses is not properly regulated this can disrupt communication between the neurons, leading to diseases like schizophrenia and autism. As the brain develops, it first forms an excess of synapses and later eliminates unnecessary or weak connections. Various factors, such gene expression or a neuron’s level of activity, regulate this turnover process. However, neurons cannot do this alone, and rely on other types of cells to help regulate their behavior. In the central nervous system, for example, a cell called an astrocyte is known to support the formation and activity of synapses. Now, Hill and Blaeser et al. show that astrocytes also exert influence over synaptic turnover during development, leading to long lasting changes in the number of synapses. Hill, Blaeser et al. revealed that disrupting activity of the signaling pathway known as Sonic hedgehog, or Shh for short, in the astrocytes of mice led to disordered synaptic connections. Notably, neurons produce Shh, suggesting that neurons use this signaling pathway to communicate to specific astrocyte partners. Further experiments showed that reducing astrocyte’s ability to respond to Shh impaired synaptic turnover as the brain developed, leading to an overabundance of synapses. Importantly, these effects were only found to influence neuron populations associated with astrocytes that actively use Shh signaling. This suggests that distinct populations of neurons and astrocytes interact in specialized ways to build the connections within the nervous system. To address how astrocytes use Shh signaling to regulate synaptic turnover, Hill, Blaeser et al. examined gene expression changes in astrocytes that lack Shh signaling. Astrocytes with a reduced capacity to respond to Shh were found to have lower levels of a protein responsible for transporting potassium ions into and out of the cell. This impairs astrocyte’s ability to regulate neuronal activity, which may lead to a failure in eliminating unnecessary synapses. Understanding how synapses are controlled and organized by astrocytes could help identify new ways to treat diseases of the developing nervous system. However, further studies would be needed to improve our understanding of how this process works.
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Affiliation(s)
- Steven A Hill
- Department of Biology, Drexel University, Philadelphia, United States
| | - Andrew S Blaeser
- Department of Biology, Drexel University, Philadelphia, United States
| | - Austin A Coley
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States
| | - Yajun Xie
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | | | - Corey C Harwell
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Wen-Jun Gao
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States
| | - A Denise R Garcia
- Department of Biology, Drexel University, Philadelphia, United States.,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States
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