151
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Almeida-Filho DG, Queiroz CM, Ribeiro S. Memory corticalization triggered by REM sleep: mechanisms of cellular and systems consolidation. Cell Mol Life Sci 2018; 75:3715-3740. [PMID: 30054638 PMCID: PMC11105475 DOI: 10.1007/s00018-018-2886-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 06/27/2018] [Accepted: 07/19/2018] [Indexed: 01/29/2023]
Abstract
Once viewed as a passive physiological state, sleep is a heterogeneous and complex sequence of brain states with essential effects on synaptic plasticity and neuronal functioning. Rapid-eye-movement (REM) sleep has been shown to promote calcium-dependent plasticity in principal neurons of the cerebral cortex, both during memory consolidation in adults and during post-natal development. This article reviews the plasticity mechanisms triggered by REM sleep, with a focus on the emerging role of kinases and immediate-early genes for the progressive corticalization of hippocampus-dependent memories. The body of evidence suggests that memory corticalization triggered by REM sleep is a systemic phenomenon with cellular and molecular causes.
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Affiliation(s)
- Daniel G Almeida-Filho
- Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, 59056-450, Brazil
| | - Claudio M Queiroz
- Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, 59056-450, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, 59056-450, Brazil.
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152
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Attardo A, Lu J, Kawashima T, Okuno H, Fitzgerald JE, Bito H, Schnitzer MJ. Long-Term Consolidation of Ensemble Neural Plasticity Patterns in Hippocampal Area CA1. Cell Rep 2018; 25:640-650.e2. [DOI: 10.1016/j.celrep.2018.09.064] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/27/2018] [Accepted: 09/19/2018] [Indexed: 12/20/2022] Open
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153
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França TFA, Monserrat JM. How the Hippocampus Represents Memories: Making Sense of Memory Allocation Studies. Bioessays 2018; 40:e800068. [PMID: 30176065 DOI: 10.1002/bies.201800068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 08/15/2018] [Indexed: 01/11/2023]
Abstract
In recent years there has been a wealth of studies investigating how memories are allocated in the hippocampus. Some of those studies showed that it is possible to manipulate the identity of neurons recruited to represent a given memory without affecting the memory's behavioral expression. Those findings raised questions about how the hippocampus represents memories, with some researchers arguing that hippocampal neurons do not represent fixed stimuli. Herein, an alternative hypothesis is argued. Neurons in high-order brain regions can be tuned to multiple dimensions, forming complex, abstract representations. It is argued that such complex receptive fields allow those neurons to show some flexibility in their responses while still representing relatively fixed sets of stimuli. Moreover, it is pointed out that changes induced by artificial manipulation of cell assemblies are not completely redundant-the observed behavioral redundancy does not imply cognitive redundancy, as different, but similar, memories may induce the same behavior.
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Affiliation(s)
- Thiago F A França
- Programa de Pós-graduação em Ciências Fisiológicas, Universidade Federal do Rio Grande-FURG, Rio Grande, Rio Grande do Sul, Brazil
| | - José M Monserrat
- Programa de Pós-graduação em Ciências Fisiológicas, Universidade Federal do Rio Grande-FURG, Rio Grande, Rio Grande do Sul, Brazil.,Instituto de Ciências Biológicas, Universidade Federal do Rio Grande (FURG), Rio Grande, Rio Grande do Sul, Brazil
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154
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Super-wide-field two-photon imaging with a micro-optical device moving in post-objective space. Nat Commun 2018; 9:3550. [PMID: 30177699 PMCID: PMC6120955 DOI: 10.1038/s41467-018-06058-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 08/14/2018] [Indexed: 11/08/2022] Open
Abstract
Wide-field imaging of neural activity at a cellular resolution is a current challenge in neuroscience. To address this issue, wide-field two-photon microscopy has been developed; however, the field size is limited by the objective size. Here, we develop a micro-opto-mechanical device that rotates within the post-objective space between the objective and brain tissue. Two-photon microscopy with this device enables sub-second sequential calcium imaging of left and right mouse sensory forelimb areas 6 mm apart. When imaging the rostral and caudal motor forelimb areas (RFA and CFA) 2 mm apart, we found high pairwise correlations in spontaneous activity between RFA and CFA neurons and between an RFA neuron and its putative axons in CFA. While mice performed a sound-triggered forelimb-movement task, the population activity between RFA and CFA covaried across trials, although the field-averaged activity was similar across trials. The micro-opto-mechanical device in the post-objective space provides a novel and flexible design to clarify the correlation structure between distant brain areas at subcellular and population levels.
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155
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Kao YC, Wang IF, Tsai KJ. miRNA-34c Overexpression Causes Dendritic Loss and Memory Decline. Int J Mol Sci 2018; 19:ijms19082323. [PMID: 30096777 PMCID: PMC6121231 DOI: 10.3390/ijms19082323] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 07/25/2018] [Accepted: 08/03/2018] [Indexed: 01/03/2023] Open
Abstract
Microribonucleic acids (miRNAs) play a pivotal role in numerous aspects of the nervous system and are increasingly recognized as key regulators in neurodegenerative diseases. This study hypothesized that miR-34c, a miRNA expressed in mammalian hippocampi whose expression level can alter the hippocampal dendritic spine density, could induce memory impairment akin to that of patients with Alzheimer’s disease (AD) in mice. In this study, we showed that miR-34c overexpression in hippocampal neurons negatively regulated dendritic length and spine density. Hippocampal neurons transfected with miR-34c had shorter dendrites on average and fewer filopodia and spines than those not transfected with miR-34c (control mice). Because dendrites and synapses are key sites for signal transduction and fundamental structures for memory formation and storage, disrupted dendrites can contribute to AD. Therefore, we supposed that miR-34c, through its effects on dendritic spine density, influences synaptic plasticity and plays a key role in AD pathogenesis.
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Affiliation(s)
- Yu-Chia Kao
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan.
- Department of Pediatrics, E-Da Hospital, Kaohsiung 824, Taiwan.
| | - I-Fang Wang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan.
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
| | - Kuen-Jer Tsai
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan.
- Research Center of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan.
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156
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Tropea D, Hardingham N, Millar K, Fox K. Mechanisms underlying the role of DISC1 in synaptic plasticity. J Physiol 2018; 596:2747-2771. [PMID: 30008190 PMCID: PMC6046077 DOI: 10.1113/jp274330] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 02/02/2018] [Indexed: 12/11/2022] Open
Abstract
Disrupted in schizophrenia 1 (DISC1) is an important hub protein, forming multimeric complexes by self-association and interacting with a large number of synaptic and cytoskeletal molecules. The synaptic location of DISC1 in the adult brain suggests a role in synaptic plasticity, and indeed, a number of studies have discovered synaptic plasticity impairments in a variety of different DISC1 mutants. This review explores the possibility that DISC1 is an important molecule for organizing proteins involved in synaptic plasticity and examines why mutations in DISC1 impair plasticity. It concentrates on DISC1's role in interacting with synaptic proteins, controlling dendritic structure and cellular trafficking of mRNA, synaptic vesicles and mitochondria. N-terminal directed mutations appear to impair synaptic plasticity through interactions with phosphodiesterase 4B (PDE4B) and hence protein kinase A (PKA)/GluA1 and PKA/cAMP response element-binding protein (CREB) signalling pathways, and affect spine structure through interactions with kalirin 7 (Kal-7) and Rac1. C-terminal directed mutations also impair plasticity possibly through altered interactions with lissencephaly protein 1 (LIS1) and nuclear distribution protein nudE-like 1 (NDEL1), thereby affecting developmental processes such as dendritic structure and spine maturation. Many of the same molecules involved in DISC1's cytoskeletal interactions are also involved in intracellular trafficking, raising the possibility that impairments in intracellular trafficking affect cytoskeletal development and vice versa. While the multiplicity of DISC1 protein interactions makes it difficult to pinpoint a single causal signalling pathway, we suggest that the immediate-term effects of N-terminal influences on GluA1, Rac1 and CREB, coupled with the developmental effects of C-terminal influences on trafficking and the cytoskeleton make up the two main branches of DISC1's effect on synaptic plasticity and dendritic spine stability.
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Affiliation(s)
- Daniela Tropea
- Neurospychiatric GeneticsTrinity Center for Health Sciences and Trinity College Institute of Neuroscience (TCIN)Trinity College DublinDublinIreland
| | - Neil Hardingham
- School of BiosciencesMuseum AvenueCardiff UniversityCardiffUK
| | - Kirsty Millar
- Centre for Genomic & Experimental MedicineMRC Institute of Genetics & Molecular MedicineWestern General HospitalUniversity of EdinburghCrewe RoadEdinburghUK
| | - Kevin Fox
- School of BiosciencesMuseum AvenueCardiff UniversityCardiffUK
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157
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Doron A, Goshen I. Investigating the transition from recent to remote memory using advanced tools. Brain Res Bull 2018; 141:35-43. [DOI: 10.1016/j.brainresbull.2017.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 08/27/2017] [Accepted: 09/11/2017] [Indexed: 11/30/2022]
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158
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Pfeiffer T, Poll S, Bancelin S, Angibaud J, Inavalli VK, Keppler K, Mittag M, Fuhrmann M, Nägerl UV. Chronic 2P-STED imaging reveals high turnover of dendritic spines in the hippocampus in vivo. eLife 2018; 7:34700. [PMID: 29932052 PMCID: PMC6014725 DOI: 10.7554/elife.34700] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 06/05/2018] [Indexed: 11/13/2022] Open
Abstract
Rewiring neural circuits by the formation and elimination of synapses is thought to be a key cellular mechanism of learning and memory in the mammalian brain. Dendritic spines are the postsynaptic structural component of excitatory synapses, and their experience-dependent plasticity has been extensively studied in mouse superficial cortex using two-photon microscopy in vivo. By contrast, very little is known about spine plasticity in the hippocampus, which is the archetypical memory center of the brain, mostly because it is difficult to visualize dendritic spines in this deeply embedded structure with sufficient spatial resolution. We developed chronic 2P-STED microscopy in mouse hippocampus, using a ‘hippocampal window’ based on resection of cortical tissue and a long working distance objective for optical access. We observed a two-fold higher spine density than previous studies and measured a spine turnover of ~40% within 4 days, which depended on spine size. We thus provide direct evidence for a high level of structural rewiring of synaptic circuits and new insights into the structure-dynamics relationship of hippocampal spines. Having established chronic super-resolution microscopy in the hippocampus in vivo, our study enables longitudinal and correlative analyses of nanoscale neuroanatomical structures with genetic, molecular and behavioral experiments.
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Affiliation(s)
- Thomas Pfeiffer
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Stefanie Poll
- Neuroimmunology and Imaging Group, German Center for Neurodegenerative Diseases, Bonn, Germany
| | - Stephane Bancelin
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Julie Angibaud
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Vvg Krishna Inavalli
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Kevin Keppler
- Light Microscope Facility, German Center for Neurodegenerative Diseases, Bonn, Germany
| | - Manuel Mittag
- Neuroimmunology and Imaging Group, German Center for Neurodegenerative Diseases, Bonn, Germany
| | - Martin Fuhrmann
- Neuroimmunology and Imaging Group, German Center for Neurodegenerative Diseases, Bonn, Germany
| | - U Valentin Nägerl
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
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159
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Mau W, Sullivan DW, Kinsky NR, Hasselmo ME, Howard MW, Eichenbaum H. The Same Hippocampal CA1 Population Simultaneously Codes Temporal Information over Multiple Timescales. Curr Biol 2018; 28:1499-1508.e4. [PMID: 29706516 DOI: 10.1016/j.cub.2018.03.051] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 03/16/2018] [Accepted: 03/22/2018] [Indexed: 11/18/2022]
Abstract
It has long been hypothesized that a primary function of the hippocampus is to discover and exploit temporal relationships between events. Previously, it has been reported that sequences of "time cells" in the hippocampus extend for tens of seconds. Other studies have shown that neuronal firing in the hippocampus fluctuates over hours and days. Both of these mechanisms could enable temporal encoding of events over very different timescales. However, thus far, these two classes of phenomena have never been observed simultaneously, which is necessary to ascribe broad-range temporal coding to the hippocampus. Using in vivo calcium imaging in unrestrained mice, we observed sequences of hippocampal neurons that bridged a 10 s delay. Similar sequences were observed over multiple days, but the set of neurons participating in those sequences changed gradually. Thus, the same population of neurons that encodes temporal information over seconds can also be used to distinguish periods of time over much longer timescales. These results unify two previously separate paradigms of temporal processing in the hippocampus that support episodic memory.
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Affiliation(s)
- William Mau
- Center for Memory and Brain, Boston University, Commonwealth Avenue, Boston, MA 02215, USA; Graduate Program for Neuroscience, Boston University, Commonwealth Avenue, Boston, MA 02215, USA.
| | - David W Sullivan
- Center for Memory and Brain, Boston University, Commonwealth Avenue, Boston, MA 02215, USA
| | - Nathaniel R Kinsky
- Center for Memory and Brain, Boston University, Commonwealth Avenue, Boston, MA 02215, USA; Graduate Program for Neuroscience, Boston University, Commonwealth Avenue, Boston, MA 02215, USA
| | - Michael E Hasselmo
- Center for Memory and Brain, Boston University, Commonwealth Avenue, Boston, MA 02215, USA
| | - Marc W Howard
- Center for Memory and Brain, Boston University, Commonwealth Avenue, Boston, MA 02215, USA
| | - Howard Eichenbaum
- Center for Memory and Brain, Boston University, Commonwealth Avenue, Boston, MA 02215, USA
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160
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
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161
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Nemeth VL, Must A, Horvath S, Király A, Kincses ZT, Vécsei L. Gender-Specific Degeneration of Dementia-Related Subcortical Structures Throughout the Lifespan. J Alzheimers Dis 2018; 55:865-880. [PMID: 27792015 DOI: 10.3233/jad-160812] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Age-related changes in brain structure are a question of interest to a broad field of research. Structural decline has been consistently, but not unambiguously, linked to functional consequences, including cognitive impairment and dementia. One of the areas considered of crucial importance throughout this process is the medial temporal lobe, and primarily the hippocampal region. Gender also has a considerable effect on volume deterioration of subcortical grey matter (GM) structures, such as the hippocampus. The influence of age×gender interaction on disproportionate GM volume changes might be mediated by hormonal effects on the brain. Hippocampal volume loss appears to become accelerated in the postmenopausal period. This decline might have significant influences on neuroplasticity in the CA1 region of the hippocampus highly vulnerable to pathological influences. Additionally, menopause has been associated with critical pathobiochemical changes involved in neurodegeneration. The micro- and macrostructural alterations and consequent functional deterioration of critical hippocampal regions might result in clinical cognitive impairment-especially if there already is a decline in the cognitive reserve capacity. Several lines of potential vulnerability factors appear to interact in the menopausal period eventually leading to cognitive decline, mild cognitive impairment, or Alzheimer's disease. This focused review aims to delineate the influence of unmodifiable risk factors of neurodegenerative processes, i.e., age and gender, on critical subcortical GM structures in the light of brain derived estrogen effects. The menopausal period appears to be of key importance for the risk of cognitive decline representing a time of special vulnerability for molecular, structural, and functional influences and offering only a narrow window for potential protective effects.
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Affiliation(s)
- Viola Luca Nemeth
- Department of Neurology, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Anita Must
- Department of Neurology, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Szatmar Horvath
- Department of Psychiatry, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Andras Király
- Department of Neurology, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Zsigmond Tamas Kincses
- Department of Neurology, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Szeged, Hungary.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno, Czech Republic
| | - László Vécsei
- Department of Neurology, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Neuroscience Research Group, Szeged, Hungary
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162
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Homeostatic Plasticity in the Hippocampus Facilitates Memory Extinction. Cell Rep 2018; 22:1451-1461. [DOI: 10.1016/j.celrep.2018.01.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 11/25/2017] [Accepted: 01/09/2018] [Indexed: 11/19/2022] Open
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163
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Ziv NE. Maintaining the active zone: Demand, supply and disposal of core active zone proteins. Neurosci Res 2018; 127:70-77. [DOI: 10.1016/j.neures.2017.09.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/26/2017] [Indexed: 11/29/2022]
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164
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Synaptic Tenacity or Lack Thereof: Spontaneous Remodeling of Synapses. Trends Neurosci 2018; 41:89-99. [DOI: 10.1016/j.tins.2017.12.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/22/2017] [Accepted: 12/04/2017] [Indexed: 11/18/2022]
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165
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Pfeiffer BE. The content of hippocampal "replay". Hippocampus 2018; 30:6-18. [PMID: 29266510 PMCID: PMC7027863 DOI: 10.1002/hipo.22824] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/11/2017] [Accepted: 12/19/2017] [Indexed: 11/07/2022]
Abstract
One of the most striking features of the hippocampal network is its ability to self-generate neuronal sequences representing temporally compressed, spatially coherent paths. These brief events, often termed "replay" in the scientific literature, are largely confined to non-exploratory states such as sleep or quiet rest. Early studies examining the content of replay noted a strong correlation between the encoded spatial information and the animal's prior behavior; thus, replay was initially hypothesized to play a role in memory formation and/or systems-level consolidation via "off-line" reactivation of previous experiences. However, recent findings indicate that replay may also serve as a memory retrieval mechanism to guide future behavior or may be an incidental reflection of pre-existing network assemblies. Here, I will review what is known regarding the content of replay events and their correlation with past and future actions, and I will discuss how this knowledge might inform or constrain models which seek to explain the circuit-level mechanisms underlying these events and their role in mnemonic processes.
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Affiliation(s)
- Brad E Pfeiffer
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, Texas, 75390
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166
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Abstract
The use of in vivo two-photon microscopy in mouse models of Alzheimer's disease (AD) has propelled studies of disease mechanisms and treatments. For instance, this approach allowed for the first time to study in the intact brain the dynamics of individual amyloid plaques, and the effects of anti-amyloid therapies on plaque formation and growth. Moreover, by combining two-photon microscopy with fluorescent calcium indicators, an amyloid-dependent abnormal hyperactivity of cortical and hippocampal neurons was revealed as a primary neuronal impairment, which was not predicted from previous in vitro analyses. Here, a method for in vivo two-photon calcium imaging with single-cell and single-action potential accuracy in the hippocampus of Alzheimer mouse models is presented.
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Affiliation(s)
- Marc Aurel Busche
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, MassGeneral Institute for Neurodegenerative Disease, Charlestown, MA, USA.
- Department of Psychiatry and Psychotherapy, Technical University of Munich, Munich, Germany.
- Munich Cluster for Systems Neurology, Munich, Germany.
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167
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Turtaev S, Leite IT, Altwegg-Boussac T, Pakan JMP, Rochefort NL, Čižmár T. High-fidelity multimode fibre-based endoscopy for deep brain in vivo imaging. LIGHT, SCIENCE & APPLICATIONS 2018; 7:92. [PMID: 30479758 PMCID: PMC6249210 DOI: 10.1038/s41377-018-0094-x] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 11/01/2018] [Accepted: 11/04/2018] [Indexed: 05/06/2023]
Abstract
Progress in neuroscience relies on new techniques for investigating the complex dynamics of neuronal networks. An ongoing challenge is to achieve minimally invasive and high-resolution observations of neuronal activity in vivo inside deep brain areas. Recently introduced methods for holographic control of light propagation in complex media enable the use of a hair-thin multimode optical fibre as an ultranarrow imaging tool. Compared to endoscopes based on graded-index lenses or fibre bundles, this new approach offers a footprint reduction exceeding an order of magnitude, combined with a significant enhancement in resolution. We designed a compact and high-speed system for fluorescent imaging at the tip of a fibre, achieving a resolution of 1.18 ± 0.04 µm across a 50-µm field of view, yielding 7-kilopixel images at a rate of 3.5 frames/s. Furthermore, we demonstrate in vivo observations of cell bodies and processes of inhibitory neurons within deep layers of the visual cortex and hippocampus of anaesthetised mice. This study paves the way for modern microscopy to be applied deep inside tissues of living animal models while exerting a minimal impact on their structural and functional properties.
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Affiliation(s)
- Sergey Turtaev
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, Jena, 07745 Germany
- School of Life Sciences, University of Dundee, Nethergate, Dundee, DD1 4HN UK
| | - Ivo T. Leite
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, Jena, 07745 Germany
- School of Science and Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN UK
| | - Tristan Altwegg-Boussac
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building 15, George Square, Edinburgh, EH8 9XD UK
| | - Janelle M. P. Pakan
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building 15, George Square, Edinburgh, EH8 9XD UK
- Center for Behavioral Brain Sciences, Institute of Cognitive Neurology and Dementia Research, German Center for Neurodegenerative Diseases, Leipziger Straße 44, Haus 64, Magdeburg, 39120 Germany
| | - Nathalie L. Rochefort
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building 15, George Square, Edinburgh, EH8 9XD UK
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD UK
| | - Tomáš Čižmár
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, Jena, 07745 Germany
- School of Science and Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN UK
- Institute of Scientific Instruments of CAS, Kralovopolska 147, Brno, 612 64 Czech Republic
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168
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Clopath C, Bonhoeffer T, Hübener M, Rose T. Variance and invariance of neuronal long-term representations. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0161. [PMID: 28093555 PMCID: PMC5247593 DOI: 10.1098/rstb.2016.0161] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2016] [Indexed: 12/13/2022] Open
Abstract
The brain extracts behaviourally relevant sensory input to produce appropriate motor output. On the one hand, our constantly changing environment requires this transformation to be plastic. On the other hand, plasticity is thought to be balanced by mechanisms ensuring constancy of neuronal representations in order to achieve stable behavioural performance. Yet, prominent changes in synaptic strength and connectivity also occur during normal sensory experience, indicating a certain degree of constitutive plasticity. This raises the question of how stable neuronal representations are on the population level and also on the single neuron level. Here, we review recent data from longitudinal electrophysiological and optical recordings of single-cell activity that assess the long-term stability of neuronal stimulus selectivities under conditions of constant sensory experience, during learning, and after reversible modification of sensory input. The emerging picture is that neuronal representations are stabilized by behavioural relevance and that the degree of long-term tuning stability and perturbation resistance directly relates to the functional role of the respective neurons, cell types and circuits. Using a 'toy' model, we show that stable baseline representations and precise recovery from perturbations in visual cortex could arise from a 'backbone' of strong recurrent connectivity between similarly tuned cells together with a small number of 'anchor' neurons exempt from plastic changes.This article is part of the themed issue 'Integrating Hebbian and homeostatic plasticity'.
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Affiliation(s)
- Claudia Clopath
- Bioengineering Department, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Tobias Bonhoeffer
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Mark Hübener
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Tobias Rose
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
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169
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Long-Term Optical Access to an Estimated One Million Neurons in the Live Mouse Cortex. Cell Rep 2017; 17:3385-3394. [PMID: 28009304 DOI: 10.1016/j.celrep.2016.12.004] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 11/18/2016] [Accepted: 11/30/2016] [Indexed: 11/20/2022] Open
Abstract
A major technological goal in neuroscience is to enable the interrogation of individual cells across the live brain. By creating a curved glass replacement to the dorsal cranium and surgical methods for its installation, we developed a chronic mouse preparation providing optical access to an estimated 800,000-1,100,000 individual neurons across the dorsal surface of neocortex. Post-surgical histological studies revealed comparable glial activation as in control mice. In behaving mice expressing a Ca2+ indicator in cortical pyramidal neurons, we performed Ca2+ imaging across neocortex using an epi-fluorescence macroscope and estimated that 25,000-50,000 individual neurons were accessible per mouse across multiple focal planes. Two-photon microscopy revealed dendritic morphologies throughout neocortex, allowed time-lapse imaging of individual cells, and yielded estimates of >1 million accessible neurons per mouse by serial tiling. This approach supports a variety of optical techniques and enables studies of cells across >30 neocortical areas in behaving mice.
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170
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Tesic V, Perovic M, Zaletel I, Jovanovic M, Puskas N, Ruzdijic S, Kanazir S. A single high dose of dexamethasone increases GAP-43 and synaptophysin in the hippocampus of aged rats. Exp Gerontol 2017; 98:62-69. [DOI: 10.1016/j.exger.2017.08.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 07/06/2017] [Accepted: 08/08/2017] [Indexed: 01/14/2023]
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171
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Berry KP, Nedivi E. Spine Dynamics: Are They All the Same? Neuron 2017; 96:43-55. [PMID: 28957675 DOI: 10.1016/j.neuron.2017.08.008] [Citation(s) in RCA: 304] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 05/03/2017] [Accepted: 08/04/2017] [Indexed: 11/19/2022]
Abstract
Since Cajal's first drawings of Golgi stained neurons, generations of researchers have been fascinated by the small protrusions, termed spines, studding many neuronal dendrites. Most excitatory synapses in the mammalian CNS are located on dendritic spines, making spines convenient proxies for excitatory synaptic presence. When in vivo imaging revealed that dendritic spines are dynamic structures, their addition and elimination were interpreted as excitatory synapse gain and loss, respectively. Spine imaging has since become a popular assay for excitatory circuit remodeling. In this review, we re-evaluate the validity of using spine dynamics as a straightforward reflection of circuit rewiring. Recent studies tracking both spines and synaptic markers in vivo reveal that 20% of spines lack PSD-95 and are short lived. Although they account for most spine dynamics, their remodeling is unlikely to impact long-term network structure. We discuss distinct roles that spine dynamics can play in circuit remodeling depending on synaptic content.
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Affiliation(s)
- Kalen P Berry
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Elly Nedivi
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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172
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Mongillo G, Rumpel S, Loewenstein Y. Intrinsic volatility of synaptic connections — a challenge to the synaptic trace theory of memory. Curr Opin Neurobiol 2017; 46:7-13. [DOI: 10.1016/j.conb.2017.06.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/18/2017] [Accepted: 06/27/2017] [Indexed: 02/07/2023]
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173
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Kondo M, Kobayashi K, Ohkura M, Nakai J, Matsuzaki M. Two-photon calcium imaging of the medial prefrontal cortex and hippocampus without cortical invasion. eLife 2017; 6:26839. [PMID: 28945191 PMCID: PMC5643091 DOI: 10.7554/elife.26839] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 09/25/2017] [Indexed: 12/21/2022] Open
Abstract
In vivo two-photon calcium imaging currently allows us to observe the activity of multiple neurons up to ~900 µm below the cortical surface without cortical invasion. However, many important brain areas are located deeper than this. Here, we used an 1100 nm laser that underfilled the back aperture of the objective together with red genetically encoded calcium indicators to establish two-photon calcium imaging of the intact mouse brain and detect neural activity up to 1200 μm from the cortical surface. This imaging was obtained from the medial prefrontal cortex (the prelimbic area) and the hippocampal CA1 region. We found that neural activity before water delivery repeated at a constant interval was higher in the prelimbic area than in layer 2/3 of the secondary motor area. Reducing the invasiveness of imaging is an important strategy to reveal the intact brain processes active in cognition and memory.
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Affiliation(s)
- Masashi Kondo
- Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Japan
| | - Kenta Kobayashi
- Section of Viral Vector Development, National Institute for Physiological Sciences, Okazaki, Japan
| | - Masamichi Ohkura
- Brain and Body System Science Institute, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Junichi Nakai
- Brain and Body System Science Institute, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Masanori Matsuzaki
- Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Japan
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174
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Davis RL, Zhong Y. The Biology of Forgetting-A Perspective. Neuron 2017; 95:490-503. [PMID: 28772119 DOI: 10.1016/j.neuron.2017.05.039] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 05/26/2017] [Accepted: 05/30/2017] [Indexed: 01/23/2023]
Abstract
Pioneering research studies, beginning with those using Drosophila, have identified several molecular and cellular mechanisms for active forgetting. The currently known mechanisms for active forgetting include neurogenesis-based forgetting, interference-based forgetting, and intrinsic forgetting, the latter term describing the brain's chronic signaling systems that function to slowly degrade molecular and cellular memory traces. The best-characterized pathway for intrinsic forgetting includes "forgetting cells" that release dopamine onto engram cells, mobilizing a signaling pathway that terminates in the activation of Rac1/Cofilin to effect changes in the actin cytoskeleton and neuron/synapse structure. Intrinsic forgetting may be the default state of the brain, constantly promoting memory erasure and competing with processes that promote memory stability like consolidation. A better understanding of active forgetting will provide insights into the brain's memory management system and human brain disorders that alter active forgetting mechanisms.
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Affiliation(s)
- Ronald L Davis
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL, USA.
| | - Yi Zhong
- Tsinghua-Peking Center for Life Sciences, School for Life Sciences, Tsinghua University, Beijing, China.
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175
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Dhawale AK, Poddar R, Wolff SB, Normand VA, Kopelowitz E, Ölveczky BP. Automated long-term recording and analysis of neural activity in behaving animals. eLife 2017; 6:27702. [PMID: 28885141 PMCID: PMC5619984 DOI: 10.7554/elife.27702] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/24/2017] [Indexed: 12/26/2022] Open
Abstract
Addressing how neural circuits underlie behavior is routinely done by measuring electrical activity from single neurons in experimental sessions. While such recordings yield snapshots of neural dynamics during specified tasks, they are ill-suited for tracking single-unit activity over longer timescales relevant for most developmental and learning processes, or for capturing neural dynamics across different behavioral states. Here we describe an automated platform for continuous long-term recordings of neural activity and behavior in freely moving rodents. An unsupervised algorithm identifies and tracks the activity of single units over weeks of recording, dramatically simplifying the analysis of large datasets. Months-long recordings from motor cortex and striatum made and analyzed with our system revealed remarkable stability in basic neuronal properties, such as firing rates and inter-spike interval distributions. Interneuronal correlations and the representation of different movements and behaviors were similarly stable. This establishes the feasibility of high-throughput long-term extracellular recordings in behaving animals.
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Affiliation(s)
- Ashesh K Dhawale
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Rajesh Poddar
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Steffen Be Wolff
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Valentin A Normand
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Evi Kopelowitz
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Bence P Ölveczky
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
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176
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Dynamic Reorganization of Neuronal Activity Patterns in Parietal Cortex. Cell 2017; 170:986-999.e16. [PMID: 28823559 DOI: 10.1016/j.cell.2017.07.021] [Citation(s) in RCA: 206] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/28/2017] [Accepted: 07/13/2017] [Indexed: 01/03/2023]
Abstract
Neuronal representations change as associations are learned between sensory stimuli and behavioral actions. However, it is poorly understood whether representations for learned associations stabilize in cortical association areas or continue to change following learning. We tracked the activity of posterior parietal cortex neurons for a month as mice stably performed a virtual-navigation task. The relationship between cells' activity and task features was mostly stable on single days but underwent major reorganization over weeks. The neurons informative about task features (trial type and maze locations) changed across days. Despite changes in individual cells, the population activity had statistically similar properties each day and stable information for over a week. As mice learned additional associations, new activity patterns emerged in the neurons used for existing representations without greatly affecting the rate of change of these representations. We propose that dynamic neuronal activity patterns could balance plasticity for learning and stability for memory.
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177
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Hoxha E, Lippiello P, Scelfo B, Tempia F, Ghirardi M, Miniaci MC. Maturation, Refinement, and Serotonergic Modulation of Cerebellar Cortical Circuits in Normal Development and in Murine Models of Autism. Neural Plast 2017; 2017:6595740. [PMID: 28894610 PMCID: PMC5574313 DOI: 10.1155/2017/6595740] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 07/06/2017] [Accepted: 07/25/2017] [Indexed: 12/13/2022] Open
Abstract
The formation of the complex cerebellar cortical circuits follows different phases, with initial synaptogenesis and subsequent processes of refinement guided by a variety of mechanisms. The regularity of the cellular and synaptic organization of the cerebellar cortex allowed detailed studies of the structural plasticity mechanisms underlying the formation of new synapses and retraction of redundant ones. For the attainment of the monoinnervation of the Purkinje cell by a single climbing fiber, several signals are involved, including electrical activity, contact signals, homosynaptic and heterosynaptic interaction, calcium transients, postsynaptic receptors, and transduction pathways. An important role in this developmental program is played by serotonergic projections that, acting on temporally and spatially regulated postsynaptic receptors, induce and modulate the phases of synaptic formation and maturation. In the adult cerebellar cortex, many developmental mechanisms persist but play different roles, such as supporting synaptic plasticity during learning and formation of cerebellar memory traces. A dysfunction at any stage of this process can lead to disorders of cerebellar origin, which include autism spectrum disorders but are not limited to motor deficits. Recent evidence in animal models links impairment of Purkinje cell function with autism-like symptoms including sociability deficits, stereotyped movements, and interspecific communication by vocalization.
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Affiliation(s)
- Eriola Hoxha
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Torino, Italy
- Department of Neuroscience, University of Torino, Torino, Italy
| | | | - Bibiana Scelfo
- Department of Neuroscience, University of Torino, Torino, Italy
| | - Filippo Tempia
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Torino, Italy
- Department of Neuroscience, University of Torino, Torino, Italy
- National Institute of Neuroscience (INN), Torino, Italy
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178
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Schaefer N, Rotermund C, Blumrich EM, Lourenco MV, Joshi P, Hegemann RU, Jamwal S, Ali N, García Romero EM, Sharma S, Ghosh S, Sinha JK, Loke H, Jain V, Lepeta K, Salamian A, Sharma M, Golpich M, Nawrotek K, Paidi RK, Shahidzadeh SM, Piermartiri T, Amini E, Pastor V, Wilson Y, Adeniyi PA, Datusalia AK, Vafadari B, Saini V, Suárez-Pozos E, Kushwah N, Fontanet P, Turner AJ. The malleable brain: plasticity of neural circuits and behavior - a review from students to students. J Neurochem 2017. [PMID: 28632905 DOI: 10.1111/jnc.14107] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
One of the most intriguing features of the brain is its ability to be malleable, allowing it to adapt continually to changes in the environment. Specific neuronal activity patterns drive long-lasting increases or decreases in the strength of synaptic connections, referred to as long-term potentiation and long-term depression, respectively. Such phenomena have been described in a variety of model organisms, which are used to study molecular, structural, and functional aspects of synaptic plasticity. This review originated from the first International Society for Neurochemistry (ISN) and Journal of Neurochemistry (JNC) Flagship School held in Alpbach, Austria (Sep 2016), and will use its curriculum and discussions as a framework to review some of the current knowledge in the field of synaptic plasticity. First, we describe the role of plasticity during development and the persistent changes of neural circuitry occurring when sensory input is altered during critical developmental stages. We then outline the signaling cascades resulting in the synthesis of new plasticity-related proteins, which ultimately enable sustained changes in synaptic strength. Going beyond the traditional understanding of synaptic plasticity conceptualized by long-term potentiation and long-term depression, we discuss system-wide modifications and recently unveiled homeostatic mechanisms, such as synaptic scaling. Finally, we describe the neural circuits and synaptic plasticity mechanisms driving associative memory and motor learning. Evidence summarized in this review provides a current view of synaptic plasticity in its various forms, offers new insights into the underlying mechanisms and behavioral relevance, and provides directions for future research in the field of synaptic plasticity. Read the Editorial Highlight for this article on page 788. Cover Image for this issue: doi: 10.1111/jnc.13815.
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Affiliation(s)
- Natascha Schaefer
- Institute for Clinical Neurobiology, Julius-Maximilians-University of Wuerzburg, Würzburg, Germany
| | - Carola Rotermund
- German Center of Neurodegenerative Diseases, University of Tuebingen, Tuebingen, Germany
| | - Eva-Maria Blumrich
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| | - Mychael V Lourenco
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pooja Joshi
- Inserm UMR 1141, Robert Debre Hospital, Paris, France
| | - Regina U Hegemann
- Department of Psychology, Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Sumit Jamwal
- Department of Pharmacology, ISF College of Pharmacy, Moga, Punjab, India
| | - Nilufar Ali
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | | | - Sorabh Sharma
- Neuropharmacology Division, Department of Pharmacy, Birla Institute of Technology and Science, Pilani, Rajasthan, India
| | - Shampa Ghosh
- National Institute of Nutrition (NIN), Indian Council of Medical Research (ICMR), Tarnaka, Hyderabad, India
| | - Jitendra K Sinha
- National Institute of Nutrition (NIN), Indian Council of Medical Research (ICMR), Tarnaka, Hyderabad, India
| | - Hannah Loke
- Hudson Institute of Medical Research, Melbourne, Victoria, Australia.,Department of Molecular and Translational Science, Monash University, Melbourne, Victoria, Australia
| | - Vishal Jain
- Defence Institute of Physiology and Allied Sciences, Delhi, India
| | - Katarzyna Lepeta
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Ahmad Salamian
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Mahima Sharma
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Mojtaba Golpich
- Department of Medicine, University Kebangsaan Malaysia Medical Centre (HUKM), Cheras, Kuala Lumpur, Malaysia
| | - Katarzyna Nawrotek
- Department of Process Thermodynamics, Faculty of Process and Environmental Engineering, Lodz University of Technology, Lodz, Poland
| | - Ramesh K Paidi
- CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Sheila M Shahidzadeh
- Department of Biology, Program in Neuroscience, Syracuse University, Syracuse, New York, USA
| | - Tetsade Piermartiri
- Programa de Pós-Graduação em Neurociências, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil
| | - Elham Amini
- Department of Medicine, University Kebangsaan Malaysia Medical Centre (HUKM), Cheras, Kuala Lumpur, Malaysia
| | - Veronica Pastor
- Instituto de Biología Celular y Neurociencia Prof. Eduardo De Robertis, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Yvette Wilson
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia
| | - Philip A Adeniyi
- Cell Biology and Neurotoxicity Unit, Department of Anatomy, College of Medicine and Health Sciences, Afe Babalola University, Ado - Ekiti, Ekiti State, Nigeria
| | | | - Benham Vafadari
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Vedangana Saini
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Edna Suárez-Pozos
- Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Toxicología, México
| | - Neetu Kushwah
- Defence Institute of Physiology and Allied Sciences, Delhi, India
| | - Paula Fontanet
- Division of Molecular and Cellular Neuroscience, Institute of Cellular Biology and Neuroscience (IBCN), CONICET-UBA, School of Medicine, Buenos Aires, Argentina
| | - Anthony J Turner
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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179
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Zhu L, Wang L, Ju F, Ran Y, Wang C, Zhang S. Transient global cerebral ischemia induces rapid and sustained reorganization of synaptic structures. J Cereb Blood Flow Metab 2017; 37:2756-2767. [PMID: 27798269 PMCID: PMC5536786 DOI: 10.1177/0271678x16674736] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Ischemia can cause rapid neuronal damage. Previous studies have suggested that synaptic structures and cortical functions can be rescued if therapeutic interventions are applied in time, but the structural basis for this resilience remains incompletely understood. Here, we investigated the restoration of synaptic structures and postischemic plasticity of dendritic spines in the somatosensory cortices of mice by taking advantage of a reversible global cerebral ischemia model. Intravital two-photon imaging revealed that although dendritic structures were rapidly distorted after global ischemia, only a small percentage of spines were actually lost after transient ischemia. Electron microscopy indicated that most presynaptic electron-dense structures were still apposed to postsynaptic densities, and that the majority of disrupted synaptic structures were rapidly reinstated following reperfusion after transient ischemia. Repeated imaging suggested that restored dendrites survived the initial ischemia -reperfusion challenge. Importantly, spines on the restored dendrites underwent a rapid and sustained structural reorganization following transient ischemia. These findings suggested that disrupted synapses during transient ischemia could be rapidly restored after ischemia/reperfusion, and that restored dendritic structures remained plastic to rebuild the cortical network.
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Affiliation(s)
- Lirui Zhu
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Lei Wang
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Furong Ju
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Yanli Ran
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Cong Wang
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Shengxiang Zhang
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, China
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180
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The Retromer Supports AMPA Receptor Trafficking During LTP. Neuron 2017; 94:74-82.e5. [PMID: 28384478 DOI: 10.1016/j.neuron.2017.03.020] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 01/24/2017] [Accepted: 03/10/2017] [Indexed: 02/07/2023]
Abstract
Alterations in the function of the retromer, a multisubunit protein complex that plays a specialized role in endosomal sorting, have been linked to Alzheimer's and Parkinson's diseases, yet little is known about the retromer's role in the mature brain. Using in vivo knockdown of the critical retromer component VPS35, we demonstrate a specific role for this endosomal sorting complex in the trafficking of AMPA receptors during NMDA-receptor-dependent LTP at mature hippocampal synapses. The impairment of LTP due to VPS35 knockdown was mechanistically independent of any role of the retromer in the production of Aβ from APP. Finally, we find surprising differences between Alzheimer's- and Parkinson's-disease-linked VPS35 mutations in supporting this pathway. These findings demonstrate a key role for the retromer in LTP and provide insights into how retromer malfunction in the mature brain may contribute to symptoms of common neurodegenerative diseases. VIDEO ABSTRACT.
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181
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Ozcan AS. Filopodia: A Rapid Structural Plasticity Substrate for Fast Learning. Front Synaptic Neurosci 2017; 9:12. [PMID: 28676753 PMCID: PMC5476769 DOI: 10.3389/fnsyn.2017.00012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 06/06/2017] [Indexed: 11/17/2022] Open
Abstract
Formation of new synapses between neurons is an essential mechanism for learning and encoding memories. The vast majority of excitatory synapses occur on dendritic spines, therefore, the growth dynamics of spines is strongly related to the plasticity timescales. Especially in the early stages of the developing brain, there is an abundant number of long, thin and motile protrusions (i.e., filopodia), which develop in timescales of seconds and minutes. Because of their unique morphology and motility, it has been suggested that filopodia can have a dual role in both spinogenesis and environmental sampling of potential axonal partners. I propose that filopodia can lower the threshold and reduce the time to form new dendritic spines and synapses, providing a substrate for fast learning. Based on this proposition, the functional role of filopodia during brain development is discussed in relation to learning and memory. Specifically, it is hypothesized that the postnatal brain starts with a single-stage memory system with filopodia playing a significant role in rapid structural plasticity along with the stability provided by the mushroom-shaped spines. Following the maturation of the hippocampus, this highly-plastic unitary system transitions to a two-stage memory system, which consists of a plastic temporary store and a long-term stable store. In alignment with these architectural changes, it is posited that after brain maturation, filopodia-based structural plasticity will be preserved in specific areas, which are involved in fast learning (e.g., hippocampus in relation to episodic memory). These propositions aim to introduce a unifying framework for a diversity of phenomena in the brain such as synaptogenesis, pruning and memory consolidation.
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Affiliation(s)
- Ahmet S Ozcan
- Machine Intelligence Laboratory, IBM Almaden Research CenterSan Jose, CA, United States
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182
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Tjia M, Yu X, Jammu LS, Lu J, Zuo Y. Pyramidal Neurons in Different Cortical Layers Exhibit Distinct Dynamics and Plasticity of Apical Dendritic Spines. Front Neural Circuits 2017; 11:43. [PMID: 28674487 PMCID: PMC5474458 DOI: 10.3389/fncir.2017.00043] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 05/30/2017] [Indexed: 01/28/2023] Open
Abstract
The mammalian cerebral cortex is typically organized in six layers containing multiple types of neurons, with pyramidal neurons (PNs) being the most abundant. PNs in different cortical layers have distinct morphology, physiology and functional roles in neural circuits. Therefore, their development and synaptic plasticity may also differ. Using in vivo transcranial two-photon microscopy, we followed the structural dynamics of dendritic spines on apical dendrites of layer (L) 2/3 and L5 PNs at different developmental stages. We show that the density and dynamics of spines are significantly higher in L2/3 PNs than L5 PNs in both adolescent (1 month old) and adult (4 months old) mice. While spine density of L5 PNs decreases during adolescent development due to a higher rate of spine elimination than formation, there is no net change in the spine density along apical dendrites of L2/3 PNs over this period. In addition, experiences exert differential impact on the dynamics of apical dendritic spines of PNs resided in different cortical layers. While motor skill learning promotes spine turnover on L5 PNs in the motor cortex, it does not change the spine dynamics on L2/3 PNs. In addition, neonatal sensory deprivation decreases the spine density of both L2/3 and L5 PNs, but leads to opposite changes in spine dynamics among these two populations of neurons in adolescence. In summary, our data reveal distinct dynamics and plasticity of apical dendritic spines on PNs in different layers in the living mouse cortex, which may arise from their distinct functional roles in cortical circuits.
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Affiliation(s)
- Michelle Tjia
- Department of Molecular, Cell and Developmental Biology, University of CaliforniaSanta Cruz, CA, United States
| | - Xinzhu Yu
- Department of Molecular, Cell and Developmental Biology, University of CaliforniaSanta Cruz, CA, United States
| | - Lavpreet S Jammu
- Department of Molecular, Cell and Developmental Biology, University of CaliforniaSanta Cruz, CA, United States
| | - Ju Lu
- Department of Molecular, Cell and Developmental Biology, University of CaliforniaSanta Cruz, CA, United States
| | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of CaliforniaSanta Cruz, CA, United States
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183
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Chambers AR, Rumpel S. A stable brain from unstable components: Emerging concepts and implications for neural computation. Neuroscience 2017; 357:172-184. [PMID: 28602920 DOI: 10.1016/j.neuroscience.2017.06.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/02/2017] [Accepted: 06/05/2017] [Indexed: 11/28/2022]
Abstract
Neuroscientists have often described the adult brain in similar terms to an electronic circuit board- dependent on fixed, precise connectivity. However, with the advent of technologies allowing chronic measurements of neural structure and function, the emerging picture is that neural networks undergo significant remodeling over multiple timescales, even in the absence of experimenter-induced learning or sensory perturbation. Here, we attempt to reconcile the parallel observations that critical brain functions are stably maintained, while synapse- and single-cell properties appear to be reformatted regularly throughout adult life. In this review, we discuss experimental evidence at multiple levels ranging from synapses to neuronal ensembles, suggesting that many parameters are maintained in a dynamic equilibrium. We highlight emerging hypotheses that could explain how stable brain functions may be generated from dynamic elements. Furthermore, we discuss the impact of dynamic circuit elements on neural computations, and how they could provide living neural circuits with computational abilities a fixed structure cannot offer. Taken together, recent evidence indicates that continuous dynamics are a fundamental property of neural circuits compatible with macroscopically stable behaviors. In addition, they may be a unique advantage imparting robustness and flexibility throughout life.
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Affiliation(s)
- Anna R Chambers
- Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University, Mainz, Germany; Institute of Physiology, Johannes Gutenberg University, Mainz, Germany
| | - Simon Rumpel
- Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University, Mainz, Germany; Institute of Physiology, Johannes Gutenberg University, Mainz, Germany.
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184
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Bagramyan A, Galstian T, Saghatelyan A. Motion-free endoscopic system for brain imaging at variable focal depth using liquid crystal lenses. JOURNAL OF BIOPHOTONICS 2017; 10:762-774. [PMID: 26954754 DOI: 10.1002/jbio.201500261] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 01/18/2016] [Accepted: 02/14/2016] [Indexed: 06/05/2023]
Abstract
We present a motion-free system for microendoscopic imaging of biological tissues at variable focal depths. Fixed gradient index and electrically tunable liquid crystal lenses (TLCL) were used to build the imaging optical probe. The design of the TLCL enables polarization-independent and relatively low-voltage operation, significantly improving the energy efficiency of the system. A focal shift of approximately 74 ± 3 µm could be achieved by electrically controlling the TLCL using the driving frequency at a constant voltage. The potential of the system was tested by imaging neurons and spines in thick adult mouse brain sections and in vivo, in the adult mouse brain at different focal planes. Our results indicate that the developed system may enable depth-variable imaging of morpho-functional properties of neural circuitries in freely moving animals and can be used to investigate the functioning of these circuitries under normal and pathological conditions.
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Affiliation(s)
- Arutyun Bagramyan
- Centre for Optics, Photonics and Lasers, Department of Physics, Engineering Physics and Optics, University Laval, 2375 Rue de la Terrasse, Quebec City, QC, Canada, G1V 0A6
- Quebec Mental Health Institute, 2601 chemin de la Canardière, Quebec City, QC, Canada, G1J 2G3
| | - Tigran Galstian
- Centre for Optics, Photonics and Lasers, Department of Physics, Engineering Physics and Optics, University Laval, 2375 Rue de la Terrasse, Quebec City, QC, Canada, G1V 0A6
| | - Armen Saghatelyan
- Quebec Mental Health Institute, 2601 chemin de la Canardière, Quebec City, QC, Canada, G1J 2G3
- Department of Psychiatry and Neuroscience, Faculty of Medicine, University Laval, 1050 avenue de la Médecine, Quebec City, QC, Canada, G1V 0A6
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185
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186
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MacDonald ML, Alhassan J, Newman JT, Richard M, Gu H, Kelly RM, Sampson AR, Fish KN, Penzes P, Wills ZP, Lewis DA, Sweet RA. Selective Loss of Smaller Spines in Schizophrenia. Am J Psychiatry 2017; 174:586-594. [PMID: 28359200 PMCID: PMC5800878 DOI: 10.1176/appi.ajp.2017.16070814] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE Decreased density of dendritic spines in adult schizophrenia subjects has been hypothesized to result from increased pruning of excess synapses in adolescence. In vivo imaging studies have confirmed that synaptic pruning is largely driven by the loss of large or mature synapses. Thus, increased pruning throughout adolescence would likely result in a deficit of large spines in adulthood. Here, the authors examined the density and volume of dendritic spines in deep layer 3 of the auditory cortex of 20 schizophrenia and 20 matched comparison subjects as well as aberrant voltage-gated calcium channel subunit protein expression linked to spine loss. METHOD Primary auditory cortex deep layer 3 spine density and volume was assessed in 20 pairs of schizophrenia and matched comparison subjects in an initial and replication cohort (12 and eight pairs) by immunohistochemistry-confocal microscopy. Targeted mass spectrometry was used to quantify postsynaptic density and voltage-gated calcium channel protein expression. The effect of increased voltage-gated calcium channel subunit protein expression on spine density and volume was assessed in primary rat neuronal culture. RESULTS Only the smallest spines are lost in deep layer 3 of the primary auditory cortex in subjects with schizophrenia, while larger spines are retained. Levels of the tryptic peptide ALFDFLK, found in the schizophrenia risk gene CACNB4, are inversely correlated with the density of smaller, but not larger, spines in schizophrenia subjects. Consistent with this observation, CACNB4 overexpression resulted in a lower density of smaller spines in primary neuronal cultures. CONCLUSIONS These findings require a rethinking of the overpruning hypothesis, demonstrate a link between small spine loss and a schizophrenia risk gene, and should spur more in-depth investigations of the mechanisms that govern new or small spine generation and stabilization under normal conditions as well as how this process is impaired in schizophrenia.
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Affiliation(s)
- Matthew L. MacDonald
- Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Jamil Alhassan
- Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Jason T. Newman
- Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Michelle Richard
- Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Hong Gu
- Department of Statistics, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Ryan M. Kelly
- Department of Statistics, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Alan R. Sampson
- Department of Statistics, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Kenneth N. Fish
- Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Peter Penzes
- Department of Physiology, Northwestern University Feinberg School of Medicine
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine
| | - Zachary P. Wills
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - David A. Lewis
- Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Robert A. Sweet
- Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Mental Illness Research, Education, and Clinical Center, VA Pittsburgh Healthcare System, Pittsburgh, PA
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187
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Fast high-resolution miniature two-photon microscopy for brain imaging in freely behaving mice. Nat Methods 2017; 14:713-719. [PMID: 28553965 DOI: 10.1038/nmeth.4305] [Citation(s) in RCA: 251] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/21/2017] [Indexed: 12/17/2022]
Abstract
Developments in miniaturized microscopes have enabled visualization of brain activities and structural dynamics in animals engaging in self-determined behaviors. However, it remains a challenge to resolve activity at single dendritic spines in freely behaving animals. Here, we report the design and application of a fast high-resolution, miniaturized two-photon microscope (FHIRM-TPM) that accomplishes this goal. With a headpiece weighing 2.15 g and a hollow-core photonic crystal fiber delivering 920-nm femtosecond laser pulses, the FHIRM-TPM is capable of imaging commonly used biosensors (GFP and GCaMP6) at high spatiotemporal resolution (0.64 μm laterally and 3.35 μm axially, 40 Hz at 256 × 256 pixels for raster scanning and 10,000 Hz for free-line scanning). We demonstrate the microscope's robustness with hour-long recordings of neuronal activities at the level of spines in mice experiencing vigorous body movements.
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188
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Yang W, Yuste R. In vivo imaging of neural activity. Nat Methods 2017; 14:349-359. [PMID: 28362436 DOI: 10.1038/nmeth.4230] [Citation(s) in RCA: 239] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 02/13/2017] [Indexed: 12/18/2022]
Abstract
Since the introduction of calcium imaging to monitor neuronal activity with single-cell resolution, optical imaging methods have revolutionized neuroscience by enabling systematic recordings of neuronal circuits in living animals. The plethora of methods for functional neural imaging can be daunting to the nonexpert to navigate. Here we review advanced microscopy techniques for in vivo functional imaging and offer guidelines for which technologies are best suited for particular applications.
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Affiliation(s)
- Weijian Yang
- Department of Biological Sciences, Neurotechnology Center, Columbia University, New York, New York, USA
| | - Rafael Yuste
- Department of Biological Sciences, Neurotechnology Center, Columbia University, New York, New York, USA
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189
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Sasi M, Vignoli B, Canossa M, Blum R. Neurobiology of local and intercellular BDNF signaling. Pflugers Arch 2017; 469:593-610. [PMID: 28280960 PMCID: PMC5438432 DOI: 10.1007/s00424-017-1964-4] [Citation(s) in RCA: 205] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 02/27/2017] [Accepted: 02/28/2017] [Indexed: 01/07/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of secreted proteins. Signaling cascades induced by BDNF and its receptor, the receptor tyrosine kinase TrkB, link neuronal growth and differentiation with synaptic plasticity. For this reason, interference with BDNF signaling has emerged as a promising strategy for potential treatments in psychiatric and neurological disorders. In many brain circuits, synaptically released BDNF is essential for structural and functional long-term potentiation, two prototypical cellular models of learning and memory formation. Recent studies have revealed an unexpected complexity in the synaptic communication of mature BDNF and its precursor proBDNF, not only between local pre- and postsynaptic neuronal targets but also with participation of glial cells. Here, we consider recent findings on local actions of the BDNF family of ligands at the synapse and discuss converging lines of evidence which emerge from per se conflicting results.
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Affiliation(s)
- Manju Sasi
- Institute of Clinical Neurobiology, University Hospital, University of Würzburg, 97078, Würzburg, Germany
| | - Beatrice Vignoli
- Centre for Integrative Biology (CIBIO), University of Trento, 38123, Povo, TN, Italy
| | - Marco Canossa
- Centre for Integrative Biology (CIBIO), University of Trento, 38123, Povo, TN, Italy.,European Brain Research Institute (EBRI) "Rita Levi-Montalcini", 00143, Rome, Italy
| | - Robert Blum
- Institute of Clinical Neurobiology, University Hospital, University of Würzburg, 97078, Würzburg, Germany.
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190
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Pain, opioids, and sleep: implications for restless legs syndrome treatment. Sleep Med 2017; 31:78-85. [DOI: 10.1016/j.sleep.2016.09.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 09/27/2016] [Accepted: 09/29/2016] [Indexed: 12/31/2022]
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191
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Zorec R, Parpura V, Vardjan N, Verkhratsky A. Astrocytic face of Alzheimer’s disease. Behav Brain Res 2017; 322:250-257. [DOI: 10.1016/j.bbr.2016.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 04/16/2016] [Accepted: 05/08/2016] [Indexed: 10/21/2022]
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192
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Bolger GB. The PDE4 cAMP-Specific Phosphodiesterases: Targets for Drugs with Antidepressant and Memory-Enhancing Action. ADVANCES IN NEUROBIOLOGY 2017; 17:63-102. [PMID: 28956330 DOI: 10.1007/978-3-319-58811-7_4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The PDE4 cyclic nucleotide phosphodiesterases are essential regulators of cAMP abundance in the CNS through their ability to regulate PKA activity, the phosphorylation of CREB, and other important elements of signal transduction. In pre-clinical models and in early-stage clinical trials, PDE4 inhibitors have been shown to have antidepressant and memory-enhancing activity. However, the development of clinically-useful PDE4 inhibitors for CNS disorders has been limited by variable efficacy and significant side effects. Recent structural studies have greatly enhanced our understanding of the molecular configuration of PDE4 enzymes, especially the "long" PDE4 isoforms that are abundant in the CNS. The new structural data provide a rationale for the development of a new generation of PDE4 inhibitors that specifically act on long PDE4 isoforms. These next generation PDE4 inhibitors may also be capable of targeting the interactions of select long forms with their "partner" proteins, such as RACK1, β-arrestin, and DISC1. They would therefore have the ability to affect cAMP levels in specific cellular compartments and target localized cellular functions, such as synaptic plasticity. These new agents might also be able to target PDE4 populations in select regions of the CNS that are implicated in learning and memory, affect, and cognition. Potential therapeutic uses of these agents could include affective disorders, memory enhancement, and neurogenesis.
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Affiliation(s)
- Graeme B Bolger
- Departments of Medicine and Pharmacology, University of Alabama at Birmingham, 1720 2nd Avenue South, NP 2501, Birmingham, AL, 35294-3300, USA.
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193
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Sailor KA, Schinder AF, Lledo PM. Adult neurogenesis beyond the niche: its potential for driving brain plasticity. Curr Opin Neurobiol 2016; 42:111-117. [PMID: 28040643 DOI: 10.1016/j.conb.2016.12.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/30/2016] [Accepted: 12/05/2016] [Indexed: 12/14/2022]
Abstract
Adult neurogenesis emerges as a tremendous form of plasticity with the continuous addition and loss of neurons in the adult brain. It is unclear how preexisting adult circuits generated during development are capable of modifying existing connections to accommodate the thousands of new synapses formed and exchanged each day. Here we first make parallels with sensory deprivation studies and its ability to induce preexisting non-neurogenic adult circuits to undergo massive reorganization. We then review recent studies that show high structural and synaptic plasticity in circuits directly connected to adult-born neurons. Finally, we propose future directions in the field to decipher how host circuits can accommodate new neuron integration and to determine the impact of adult neurogenesis on global brain plasticity.
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Affiliation(s)
- Kurt A Sailor
- Laboratory for Perception and Memory, Pasteur Institute, F-75015 Paris, France; Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée (UMR3571), F-75015 Paris, France
| | - Alejandro F Schinder
- Laboratory of Neuronal Plasticity, Leloir Institute (IIBBA - CONICET), Av. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina
| | - Pierre-Marie Lledo
- Laboratory for Perception and Memory, Pasteur Institute, F-75015 Paris, France; Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée (UMR3571), F-75015 Paris, France.
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194
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Long-term depression-associated signaling is required for an in vitro model of NMDA receptor-dependent synapse pruning. Neurobiol Learn Mem 2016; 138:39-53. [PMID: 27794462 DOI: 10.1016/j.nlm.2016.10.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 09/20/2016] [Accepted: 10/25/2016] [Indexed: 02/06/2023]
Abstract
Activity-dependent pruning of synaptic contacts plays a critical role in shaping neuronal circuitry in response to the environment during postnatal brain development. Although there is compelling evidence that shrinkage of dendritic spines coincides with synaptic long-term depression (LTD), and that LTD is accompanied by synapse loss, whether NMDA receptor (NMDAR)-dependent LTD is a required step in the progression toward synapse pruning is still unknown. Using repeated applications of NMDA to induce LTD in dissociated rat neuronal cultures, we found that synapse density, as measured by colocalization of fluorescent markers for pre- and postsynaptic structures, was decreased irrespective of the presynaptic marker used, post-treatment recovery time, and the dendritic location of synapses. Consistent with previous studies, we found that synapse loss could occur without apparent net spine loss or cell death. Furthermore, synapse loss was unlikely to require direct contact with microglia, as the number of these cells was minimal in our culture preparations. Supporting a model by which NMDAR-LTD is required for synapse loss, the effect of NMDA on fluorescence colocalization was prevented by phosphatase and caspase inhibitors. In addition, gene transcription and protein translation also appeared to be required for loss of putative synapses. These data support the idea that NMDAR-dependent LTD is a required step in synapse pruning and contribute to our understanding of the basic mechanisms of this developmental process.
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195
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Dvorkin R, Ziv NE. Relative Contributions of Specific Activity Histories and Spontaneous Processes to Size Remodeling of Glutamatergic Synapses. PLoS Biol 2016; 14:e1002572. [PMID: 27776122 PMCID: PMC5077109 DOI: 10.1371/journal.pbio.1002572] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 09/27/2016] [Indexed: 11/18/2022] Open
Abstract
The idea that synaptic properties are defined by specific pre- and postsynaptic activity histories is one of the oldest and most influential tenets of contemporary neuroscience. Recent studies also indicate, however, that synaptic properties often change spontaneously, even in the absence of specific activity patterns or any activity whatsoever. What, then, are the relative contributions of activity history-dependent and activity history-independent processes to changes synapses undergo? To compare the relative contributions of these processes, we imaged, in spontaneously active networks of cortical neurons, glutamatergic synapses formed between the same axons and neurons or dendrites under the assumption that their similar activity histories should result in similar size changes over timescales of days. The size covariance of such commonly innervated (CI) synapses was then compared to that of synapses formed by different axons (non-CI synapses) that differed in their activity histories. We found that the size covariance of CI synapses was greater than that of non-CI synapses; yet overall size covariance of CI synapses was rather modest. Moreover, momentary and time-averaged sizes of CI synapses correlated rather poorly, in perfect agreement with published electron microscopy-based measurements of mouse cortex synapses. A conservative estimate suggested that ~40% of the observed size remodeling was attributable to specific activity histories, whereas ~10% and ~50% were attributable to cell-wide and spontaneous, synapse-autonomous processes, respectively. These findings demonstrate that histories of naturally occurring activity patterns can direct glutamatergic synapse remodeling but also suggest that the contributions of spontaneous, possibly stochastic, processes are at least as great.
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Affiliation(s)
- Roman Dvorkin
- Technion Faculty of Medicine, Network Biology Research Laboratories, Lorry Lokey Center for Life Sciences and Engineering, Technion, Haifa, Israel
| | - Noam E Ziv
- Technion Faculty of Medicine, Network Biology Research Laboratories, Lorry Lokey Center for Life Sciences and Engineering, Technion, Haifa, Israel.,Rappaport Family Institute for Research in the Medical Sciences, Haifa, Israel
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196
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Functional and structural underpinnings of neuronal assembly formation in learning. Nat Neurosci 2016; 19:1553-1562. [PMID: 27749830 DOI: 10.1038/nn.4418] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 09/14/2016] [Indexed: 02/07/2023]
Abstract
Learning and memory are associated with the formation and modification of neuronal assemblies: populations of neurons that encode what has been learned and mediate memory retrieval upon recall. Functional studies of neuronal assemblies have progressed dramatically thanks to recent technological advances. Here we discuss how a focus on assembly formation and consolidation has provided a powerful conceptual framework to relate mechanistic studies of synaptic and circuit plasticity to behaviorally relevant aspects of learning and memory. Neurons are likely recruited to particular learning-related assemblies as a function of their relative excitabilities and synaptic activation, followed by selective strengthening of pre-existing synapses, formation of new connections and elimination of outcompeted synapses to ensure memory formation. Mechanistically, these processes involve linking transcription to circuit modification. They include the expression of immediate early genes and specific molecular and cellular events, supported by network-wide activities that are shaped and modulated by local inhibitory microcircuits.
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197
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Gipson CD, Olive MF. Structural and functional plasticity of dendritic spines - root or result of behavior? GENES BRAIN AND BEHAVIOR 2016; 16:101-117. [PMID: 27561549 DOI: 10.1111/gbb.12324] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/19/2016] [Accepted: 08/24/2016] [Indexed: 02/06/2023]
Abstract
Dendritic spines are multifunctional integrative units of the nervous system and are highly diverse and dynamic in nature. Both internal and external stimuli influence dendritic spine density and morphology on the order of minutes. It is clear that the structural plasticity of dendritic spines is related to changes in synaptic efficacy, learning and memory and other cognitive processes. However, it is currently unclear whether structural changes in dendritic spines are primary instigators of changes in specific behaviors, a consequence of behavioral changes, or both. In this review, we first examine the basic structure and function of dendritic spines in the brain, as well as laboratory methods to characterize and quantify morphological changes in dendritic spines. We then discuss the existing literature on the temporal and functional relationship between changes in dendritic spines in specific brain regions and changes in specific behaviors mediated by those regions. Although technological advancements have allowed us to better understand the functional relevance of structural changes in dendritic spines that are influenced by environmental stimuli, the role of spine dynamics as an underlying driver or consequence of behavior still remains elusive. We conclude that while it is likely that structural changes in dendritic spines are both instigators and results of behavioral changes, improved research tools and methods are needed to experimentally and directly manipulate spine dynamics in order to more empirically delineate the relationship between spine structure and behavior.
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Affiliation(s)
- C D Gipson
- Department of Psychology, Arizona State University, Tempe, AZ, USA
| | - M F Olive
- Department of Psychology, Arizona State University, Tempe, AZ, USA
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198
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Lauterbach MA, Guillon M, Desnos C, Khamsing D, Jaffal Z, Darchen F, Emiliani V. Superresolving dendritic spine morphology with STED microscopy under holographic photostimulation. NEUROPHOTONICS 2016; 3:041806. [PMID: 27413766 PMCID: PMC4916265 DOI: 10.1117/1.nph.3.4.041806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/31/2016] [Indexed: 06/06/2023]
Abstract
Emerging all-optical methods provide unique possibilities for noninvasive studies of physiological processes at the cellular and subcellular scale. On the one hand, superresolution microscopy enables observation of living samples with nanometer resolution. On the other hand, light can be used to stimulate cells due to the advent of optogenetics and photolyzable neurotransmitters. To exploit the full potential of optical stimulation, light must be delivered to specific cells or even parts of cells such as dendritic spines. This can be achieved with computer generated holography (CGH), which shapes light to arbitrary patterns by phase-only modulation. We demonstrate here in detail how CGH can be incorporated into a stimulated emission depletion (STED) microscope for photostimulation of neurons and monitoring of nanoscale morphological changes. We implement an original optical system to allow simultaneous holographic photostimulation and superresolution STED imaging. We present how synapses can be clearly visualized in live cells using membrane stains either with lipophilic organic dyes or with fluorescent proteins. We demonstrate the capabilities of this microscope to precisely monitor morphological changes of dendritic spines after stimulation. These all-optical methods for cell stimulation and monitoring are expected to spread to various fields of biological research in neuroscience and beyond.
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Affiliation(s)
- Marcel Andreas Lauterbach
- University Paris Descartes, Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité, 45, rue des Saints Pères, Paris 75006, France
| | - Marc Guillon
- University Paris Descartes, Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité, 45, rue des Saints Pères, Paris 75006, France
| | - Claire Desnos
- University Paris Descartes, Synapic Trafficking Group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité, 45, rue des Saints Pères, Paris 75006, France
| | - Dany Khamsing
- University Paris Descartes, Synapic Trafficking Group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité, 45, rue des Saints Pères, Paris 75006, France
| | - Zahra Jaffal
- University Paris Descartes, Synapic Trafficking Group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité, 45, rue des Saints Pères, Paris 75006, France
| | - François Darchen
- University Paris Descartes, Synapic Trafficking Group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité, 45, rue des Saints Pères, Paris 75006, France
| | - Valentina Emiliani
- University Paris Descartes, Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité, 45, rue des Saints Pères, Paris 75006, France
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199
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Wefelmeyer W, Puhl CJ, Burrone J. Homeostatic Plasticity of Subcellular Neuronal Structures: From Inputs to Outputs. Trends Neurosci 2016; 39:656-667. [PMID: 27637565 PMCID: PMC5236059 DOI: 10.1016/j.tins.2016.08.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/18/2016] [Accepted: 08/19/2016] [Indexed: 01/02/2023]
Abstract
Neurons in the brain are highly plastic, allowing an organism to learn and adapt to its environment. However, this ongoing plasticity is also inherently unstable, potentially leading to aberrant levels of circuit activity. Homeostatic forms of plasticity are thought to provide a means of controlling neuronal activity by avoiding extremes and allowing network stability. Recent work has shown that many of these homeostatic modifications change the structure of subcellular neuronal compartments, ranging from changes to synaptic inputs at both excitatory and inhibitory compartments to modulation of neuronal output through changes at the axon initial segment (AIS) and presynaptic terminals. Here we review these different forms of structural plasticity in neurons and the effects they may have on network function.
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Affiliation(s)
- Winnie Wefelmeyer
- Centre for Developmental Neurobiology, King's College London, New Hunt's House, Guy's Hospital Campus, London, SE1 1UL, UK.
| | - Christopher J Puhl
- Centre for Developmental Neurobiology, King's College London, New Hunt's House, Guy's Hospital Campus, London, SE1 1UL, UK
| | - Juan Burrone
- Centre for Developmental Neurobiology, King's College London, New Hunt's House, Guy's Hospital Campus, London, SE1 1UL, UK.
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200
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Talking to the neighbours: The molecular and physiological mechanisms of clustered synaptic plasticity. Neurosci Biobehav Rev 2016; 71:352-361. [PMID: 27659124 DOI: 10.1016/j.neubiorev.2016.09.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/15/2016] [Accepted: 09/18/2016] [Indexed: 11/23/2022]
Abstract
Synaptic connectivity forms the basis for neuronal communication and the storage of information. Experiences and learning of new abilities can drive remodelling of this connectivity and promotes the formation of spine clusters; dendritic segments with a higher spine density. Spines located within these segments are frequently co-activated, undergo different dynamics than synapses located outside of this dendritic compartment and have, in general, a longer lifetime. Several lines of evidence have shown that chemical synapses located close to each other share or compete for intracellular signalling molecules and structural resources. This sharing and competition directly influences spine dynamics. Spines can grow, shrink, increase or decrease the surface expression of receptors, channels and adhesion molecules or remain stable and unchanged over extended periods of time. Here we summarize recent discoveries and provide a closer look at spine clustering, dendritic segment-specific signalling and potential molecular mechanisms underlying associative and heterosynaptic plasticity.
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