1
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Foubert D, Cookson F, Ruthazer ES. Capturing a rising star: the emerging role of astrocytes in neural circuit wiring and plasticity-lessons from the visual system. NEUROPHOTONICS 2023; 10:044408. [PMID: 37766925 PMCID: PMC10520262 DOI: 10.1117/1.nph.10.4.044408] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/29/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023]
Abstract
The increasingly widespread use of calcium imaging to explore the nature of neuronal activity and circuits has unexpectedly revealed the ubiquitous presence and significance of astrocytic activity. Here, we present a brief review of visual system development, placing it in the context of recently identified roles of astrocytes in the modulation of neuronal responses and circuit plasticity, through their responses to sensory stimuli and the release of gliotransmitters.
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Affiliation(s)
- David Foubert
- Montreal Neurological Institute-Hospital, Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Finnley Cookson
- Montreal Neurological Institute-Hospital, Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Edward S. Ruthazer
- Montreal Neurological Institute-Hospital, Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
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2
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Hogg PW, Haas K. Bulk Dye Loading for In Vivo Calcium Imaging of Visual Responses in Populations of Xenopus Tectal Neurons. Cold Spring Harb Protoc 2022; 2022:pdb.prot106831. [PMID: 33782097 DOI: 10.1101/pdb.prot106831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Bulk loading of neurons with fluorescent calcium indicators in transparent albino Xenopus tadpoles offers a rapid and easy method for tracking sensory-evoked activity in large numbers of neurons within an awake developing brain circuit. In vivo two-photon time-lapse imaging of an image plane through the optic tectum allows defining receptive field properties from visual-evoked responses for studies of single-neuron and network-level encoding and plasticity. Here, we describe loading the Xenopus tadpole optic tectum with the membrane-permeable AM ester of Oregon Green 488 BAPTA-1 (OGB-1 AM) for in vivo imaging experiments.
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Affiliation(s)
- Peter W Hogg
- Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V6T2B5, Canada
| | - Kurt Haas
- Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V6T2B5, Canada
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3
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Hiramoto M, Cline HT. Tetrode Recording in the Xenopus laevis Visual System Using Multichannel Glass Electrodes. Cold Spring Harb Protoc 2021; 2021:pdb.prot107086. [PMID: 33536286 DOI: 10.1101/pdb.prot107086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Xenopus tadpole visual system shows an extraordinary extent of developmental and visual experience-dependent plasticity, establishing sophisticated neuronal response properties that guide essential survival behaviors. The external development and access to the developing visual circuit of Xenopus tadpoles make them an excellent experimental system in which to elucidate plastic changes in neuronal properties and their capacity to encode information about the visual scene. The temporal structure of neural activity encodes a significant amount of information, access to which requires recording methods with high temporal resolution. Conversely, elucidating changes in the temporal structure of neural activity requires recording over extended periods. It is challenging to maintain patch-clamp recordings over extended periods and Ca2+ imaging has limited temporal resolution. Extracellular recordings have been used in other systems for extended recording; however, spike amplitudes in the developing Xenopus visual circuit are not large enough to be captured by distant electrodes. Here we describe a juxtacellular tetrode recording method for continuous long-term recordings from neurons in intact tadpoles, which can also be exposed to diverse visual stimulation protocols. Electrode position in the tectum is stabilized by the large contact area in the tissue. Contamination of the signal from neighboring neurons is minimized by the tight contact between the glass capillaries and the dense arrangement of neurons in the tectum. This recording method enables analysis of developmental and visual experience-dependent plastic changes in neuronal response properties at higher temporal resolution and over longer periods than current methods.
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Affiliation(s)
- Masaki Hiramoto
- The Dorris Neuroscience Center, Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Hollis T Cline
- The Dorris Neuroscience Center, Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037, USA
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4
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Cline HT. Imaging Structural and Functional Dynamics in Xenopus Neurons. Cold Spring Harb Protoc 2021; 2022:pdb.top106773. [PMID: 34531329 DOI: 10.1101/pdb.top106773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In vivo time-lapse imaging has been a fruitful approach to identify structural and functional changes in the Xenopus nervous system in tadpoles and adult frogs. Structural imaging studies have identified fundamental aspects of brain connectivity, development, plasticity, and disease and have been instrumental in elucidating mechanisms regulating these events in vivo. Similarly, assessment of nervous system function using dynamic changes in calcium signals as a proxy for neuronal activity has demonstrated principles of neuron and circuit function and principles of information organization and transfer within the brain of living animals. Because of its many advantages as an experimental system, use of Xenopus has often been at the forefront of developing these imaging methods for in vivo applications. Protocols for in vivo structural and functional imaging-including cellular labeling strategies, image collection, and image analysis-will expand the use of Xenopus to understand brain development, function, and plasticity.
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Affiliation(s)
- Hollis T Cline
- Department of Neuroscience, Dorris Neuroscience Center, The Scripps Research Center, La Jolla, California 92039, USA
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5
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Davenport CM, Rajappa R, Katchan L, Taylor CR, Tsai MC, Smith CM, de Jong JW, Arnold DB, Lammel S, Kramer RH. Relocation of an Extrasynaptic GABA A Receptor to Inhibitory Synapses Freezes Excitatory Synaptic Strength and Preserves Memory. Neuron 2021; 109:123-134.e4. [PMID: 33096025 PMCID: PMC7790995 DOI: 10.1016/j.neuron.2020.09.037] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/21/2020] [Accepted: 09/25/2020] [Indexed: 11/27/2022]
Abstract
The excitatory synapse between hippocampal CA3 and CA1 pyramidal neurons exhibits long-term potentiation (LTP), a positive feedback process implicated in learning and memory in which postsynaptic depolarization strengthens synapses, promoting further depolarization. Without mechanisms for interrupting positive feedback, excitatory synapses could strengthen inexorably, corrupting memory storage. Here, we reveal a hidden form of inhibitory synaptic plasticity that prevents accumulation of excitatory LTP. We developed a knockin mouse that allows optical control of endogenous α5-subunit-containing γ-aminobutyric acid (GABA)A receptors (α5-GABARs). Induction of excitatory LTP relocates α5-GABARs, which are ordinarily extrasynaptic, to inhibitory synapses, quashing further NMDA receptor activation necessary for inducing more excitatory LTP. Blockade of α5-GABARs accelerates reversal learning, a behavioral test for cognitive flexibility dependent on repeated LTP. Hence, inhibitory synaptic plasticity occurs in parallel with excitatory synaptic plasticity, with the ensuing interruption of the positive feedback cycle of LTP serving as a possible critical early step in preserving memory.
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Affiliation(s)
- Christopher M Davenport
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Rajit Rajappa
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ljudmila Katchan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Charlotte R Taylor
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ming-Chi Tsai
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Caleb M Smith
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Johannes W de Jong
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Don B Arnold
- Department of Biology, Section of Molecular and Computational Biology, University of Southern California, Los Angeles, Los Angeles, CA 90089, USA
| | - Stephan Lammel
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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6
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Sakaki KDR, Podgorski K, Dellazizzo Toth TA, Coleman P, Haas K. Comprehensive Imaging of Sensory-Evoked Activity of Entire Neurons Within the Awake Developing Brain Using Ultrafast AOD-Based Random-Access Two-Photon Microscopy. Front Neural Circuits 2020; 14:33. [PMID: 32612514 PMCID: PMC7308460 DOI: 10.3389/fncir.2020.00033] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 05/07/2020] [Indexed: 11/18/2022] Open
Abstract
Determining how neurons transform synaptic input and encode information in action potential (AP) firing output is required for understanding dendritic integration, neural transforms and encoding. Limitations in the speed of imaging 3D volumes of brain encompassing complex dendritic arbors in vivo using conventional galvanometer mirror-based laser-scanning microscopy has hampered fully capturing fluorescent sensors of activity throughout an individual neuron's entire complement of synaptic inputs and somatic APs. To address this problem, we have developed a two-photon microscope that achieves high-speed scanning by employing inertia-free acousto-optic deflectors (AODs) for laser beam positioning, enabling random-access sampling of hundreds to thousands of points-of-interest restricted to a predetermined neuronal structure, avoiding wasted scanning of surrounding extracellular tissue. This system is capable of comprehensive imaging of the activity of single neurons within the intact and awake vertebrate brain. Here, we demonstrate imaging of tectal neurons within the brains of albino Xenopus laevis tadpoles labeled using single-cell electroporation for expression of a red space-filling fluorophore to determine dendritic arbor morphology, and either the calcium sensor jGCaMP7s or the glutamate sensor iGluSnFR as indicators of neural activity. Using discrete, point-of-interest scanning we achieve sampling rates of 3 Hz for saturation sampling of entire arbors at 2 μm resolution, 6 Hz for sequentially sampling 3 volumes encompassing the dendritic arbor and soma, and 200–250 Hz for scanning individual planes through the dendritic arbor. This system allows investigations of sensory-evoked information input-output relationships of neurons within the intact and awake brain.
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Affiliation(s)
- Kelly D R Sakaki
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | | | - Tristan A Dellazizzo Toth
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Patrick Coleman
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Kurt Haas
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
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7
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Sakaki KDR, Coleman P, Toth TD, Guerrier C, Haas K. Automating Event-detection of Brain Neuron Synaptic Activity and Action Potential Firing in vivo using a Random-access Multiphoton Laser Scanning Microscope for Real-time Analysis. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:1-7. [PMID: 30440280 DOI: 10.1109/embc.2018.8512983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Determining how a neuron computes requires an understanding of the complex spatiotemporal relationship between its input (e.g. synaptic input as a result of external stimuli) and action potential output. Recent advances in in vivo, laser-scanning multiphoton technology, known as random-access microscopy (RAM), can capture this relationship by imaging fluorescent light, emitted from calcium-sensitive biosensors responding to synaptic and action potential firing in a neuron's full dendritic arbor and cell body. Ideally, a continuous output of fluorescent intensities from the neuron would be converted to a binary output (`event', 'or no-event'). These binary events can be used to correlate temporal and spatial associations between the input and output. However, neurons contain hundreds-to-thousands of synapses on the dendritic arbors generating an enormous quantity of data composed of physiological signals, which vary greatly in shape and size. Thus, automating data-processing tasks is essential to support high-throughput analysis for real-time/post-processing operations and to improve operators' comprehension of the data used to decipher neuron computations. Here, we describe an automated software algorithm to detect brain neuron events in real-time using an acousto-optic, multiphoton, laser scanning RAM developed in our laboratory. The fluorescent light intensities, from a genetically encoded, calcium biosensor (GCAMP 6m), are measured by our RAM system and are input to our 'event-detector', which converts them to a binary output meant for real-time applications. We evaluate three algorithms for this purpose: exponentially weighted moving average, cumulative sum, and template matching; present each algorithm's performance; and discuss user-feasibility of each. We validated our system in vivo, using the visual circuit of the Xenopus laevis.
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8
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Yee AX, Hsu YT, Chen L. A metaplasticity view of the interaction between homeostatic and Hebbian plasticity. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0155. [PMID: 28093549 DOI: 10.1098/rstb.2016.0155] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2016] [Indexed: 01/25/2023] Open
Abstract
Hebbian and homeostatic plasticity are two major forms of plasticity in the nervous system: Hebbian plasticity provides a synaptic basis for associative learning, whereas homeostatic plasticity serves to stabilize network activity. While achieving seemingly very different goals, these two types of plasticity interact functionally through overlapping elements in their respective mechanisms. Here, we review studies conducted in the mammalian central nervous system, summarize known circuit and molecular mechanisms of homeostatic plasticity, and compare these mechanisms with those that mediate Hebbian plasticity. We end with a discussion of 'local' homeostatic plasticity and the potential role of local homeostatic plasticity as a form of metaplasticity that modulates a neuron's future capacity for Hebbian plasticity.This article is part of the themed issue 'Integrating Hebbian and homeostatic plasticity'.
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Affiliation(s)
- Ada X Yee
- Departments of Neurosurgery, Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Yu-Tien Hsu
- Departments of Neurosurgery, Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Lu Chen
- Departments of Neurosurgery, Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
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9
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Singh A, Abraham WC. Astrocytes and synaptic plasticity in health and disease. Exp Brain Res 2017; 235:1645-1655. [PMID: 28299411 DOI: 10.1007/s00221-017-4928-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 02/20/2017] [Indexed: 12/22/2022]
Abstract
Activity-dependent synaptic plasticity phenomena such as long-term potentiation and long-term depression are candidate mechanisms for storing information in the brain. Regulation of synaptic plasticity is critical for healthy cognition and learning and this is provided in part by metaplasticity, which can act to maintain synaptic transmission within a dynamic range and potentially prevent excitotoxicity. Metaplasticity mechanisms also allow neurons to integrate plasticity-associated signals over time. Interestingly, astrocytes appear to be critical for certain forms of synaptic plasticity and metaplasticity mechanisms. Synaptic dysfunction is increasingly viewed as an early feature of AD that is correlated with the severity of cognitive decline, and the development of these pathologies is correlated with a rise in reactive astrocytes. This review focuses on the contributions of astrocytes to synaptic plasticity and metaplasticity in normal tissue, and addresses whether astroglial pathology may lead to aberrant engagement of these mechanisms in neurological diseases such as Alzheimer's disease.
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Affiliation(s)
- A Singh
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Box 56, Dunedin, 9054, New Zealand
| | - Wickliffe C Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Box 56, Dunedin, 9054, New Zealand.
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10
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Unsain N, Barker PA. New Views on the Misconstrued: Executioner Caspases and Their Diverse Non-apoptotic Roles. Neuron 2016; 88:461-74. [PMID: 26539888 DOI: 10.1016/j.neuron.2015.08.029] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Initially characterized for their roles in apoptosis, executioner caspases have emerged as important regulators of an array of cellular activities. This is especially true in the nervous system, where sublethal caspase activity has been implicated in axonal pathfinding and branching, axonal degeneration, dendrite pruning, regeneration, long-term depression, and metaplasticity. Here we examine the roles of sublethal executioner caspase activity in nervous system development and maintenance, consider the mechanisms that locally activate and restrain these potential killers, and discuss how their activity be subverted in neurodegenerative disease.
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Affiliation(s)
- Nicolas Unsain
- Laboratorio de Neurobiología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, Instituto Nacional de Investigación Médica Córdoba-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Córdoba, Friuli 2434, Córdoba (5016), Argentina
| | - Philip A Barker
- Irving K. Barber School of Arts and Sciences, University of British Columbia, Kelowna, BC V1V 1V7, Canada.
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11
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Khakhalin AS, Koren D, Gu J, Xu H, Aizenman CD. Excitation and inhibition in recurrent networks mediate collision avoidance in Xenopus tadpoles. Eur J Neurosci 2014; 40:2948-62. [PMID: 24995793 DOI: 10.1111/ejn.12664] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/23/2014] [Accepted: 05/28/2014] [Indexed: 01/24/2023]
Abstract
Information processing in the vertebrate brain is thought to be mediated through distributed neural networks, but it is still unclear how sensory stimuli are encoded and detected by these networks, and what role synaptic inhibition plays in this process. Here we used a collision avoidance behavior in Xenopus tadpoles as a model for stimulus discrimination and recognition. We showed that the visual system of the tadpole is selective for behaviorally relevant looming stimuli, and that the detection of these stimuli first occurs in the optic tectum. By comparing visually guided behavior, optic nerve recordings, excitatory and inhibitory synaptic currents, and the spike output of tectal neurons, we showed that collision detection in the tadpole relies on the emergent properties of distributed recurrent networks within the tectum. We found that synaptic inhibition was temporally correlated with excitation, and did not actively sculpt stimulus selectivity, but rather it regulated the amount of integration between direct inputs from the retina and recurrent inputs from the tectum. Both pharmacological suppression and enhancement of synaptic inhibition disrupted emergent selectivity for looming stimuli. Taken together these findings suggested that, by regulating the amount of network activity, inhibition plays a critical role in maintaining selective sensitivity to behaviorally-relevant visual stimuli.
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Affiliation(s)
- Arseny S Khakhalin
- Department of Neuroscience, Brown University, Box G-LN, Providence, RI, 02912, USA
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12
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Global hyper-synchronous spontaneous activity in the developing optic tectum. Sci Rep 2013; 3:1552. [PMID: 23531884 PMCID: PMC3609019 DOI: 10.1038/srep01552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 03/08/2013] [Indexed: 01/19/2023] Open
Abstract
Studies of patterned spontaneous activity can elucidate how the organization of neural circuits emerges. Using in vivo two-photon Ca2+ imaging, we studied spatio-temporal patterns of spontaneous activity in the optic tectum of Xenopus tadpoles. We found rhythmic patterns of global synchronous spontaneous activity between neurons, which depends on visual experience and developmental stage. By contrast, synchronous spontaneous activity between non-neuronal cells is mediated more locally. To understand the source of the neuronal spontaneous activity, input to the tectum was systematically removed. Whereas removing input from the visual or mechanosensory system alone had little effect on patterned spontaneous activity, removing input from both systems drastically altered it. These results suggest that either input is sufficient to maintain the intrinsically generated spontaneous activity and that patterned spontaneous activity results from input from multisensory systems. Thus, the amphibian midbrain differs from the mammalian visual system, whose spontaneous activity is controlled by retinal waves.
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13
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Podgorski K, Haas K. Fast non-negative temporal deconvolution for laser scanning microscopy. JOURNAL OF BIOPHOTONICS 2013; 6:153-162. [PMID: 22438321 DOI: 10.1002/jbio.201100133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 02/27/2012] [Accepted: 02/28/2012] [Indexed: 05/31/2023]
Abstract
Laser scanning microscopy (LSM) is a common technique for high resolution fluorescent imaging. Here we describe a fast algorithm for non-negative deconvolution and apply it to readout of LSM detector photocurrents. By broadening photon impulses and deconvolving sampled photocurrent, effective quantum efficiency of the imaging system is increased. Using simulation and imaging with a custom-built two-photon microscope, we demonstrate improved fidelity of images acquired at short dwell times over a wide range of photon rates. Images formed show increased correlation-to-sample equivalent to a 25% increase in photon rate, lower noise, and reduced bleed-through compared to conventional image generation.
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Affiliation(s)
- Kaspar Podgorski
- Department of Cellular and Physiological Sciences and the Brain Research Centre, University of British Columbia, 2211 Wesbrook Mall, Vancouver, BC, V6T2B5, Canada
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14
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The BCM theory of synapse modification at 30: interaction of theory with experiment. Nat Rev Neurosci 2012; 13:798-810. [PMID: 23080416 DOI: 10.1038/nrn3353] [Citation(s) in RCA: 214] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Thirty years have passed since the publication of Elie Bienenstock, Leon Cooper and Paul Munro's 'Theory for the development of neuron selectivity: orientation specificity and binocular interaction in visual cortex', known as the BCM theory of synaptic plasticity. This theory has guided experimentalists to discover some fundamental properties of synaptic plasticity and has provided a mathematical structure that bridges molecular mechanisms and systems-level consequences of learning and memory storage.
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15
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Chen SX, Cherry A, Tari PK, Podgorski K, Kwong YKK, Haas K. The transcription factor MEF2 directs developmental visually driven functional and structural metaplasticity. Cell 2012; 151:41-55. [PMID: 23021214 DOI: 10.1016/j.cell.2012.08.028] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 06/13/2012] [Accepted: 08/23/2012] [Indexed: 10/27/2022]
Abstract
Natural sensory input shapes both structure and function of developing neurons, but how early experience-driven morphological and physiological plasticity are interrelated remains unclear. Using rapid time-lapse two-photon calcium imaging of network activity and single-neuron growth within the unanesthetized developing brain, we demonstrate that visual stimulation induces coordinated changes to neuronal responses and dendritogenesis. Further, we identify the transcription factor MEF2A/2D as a major regulator of neuronal response to plasticity-inducing stimuli directing both structural and functional changes. Unpatterned sensory stimuli that change plasticity thresholds induce rapid degradation of MEF2A/2D through a classical apoptotic pathway requiring NMDA receptors and caspases-9 and -3/7. Knockdown of MEF2A/2D alone is sufficient to induce a metaplastic shift in threshold of both functional and morphological plasticity. These findings demonstrate how sensory experience acting through altered levels of the transcription factor MEF2 fine-tunes the plasticity thresholds of brain neurons during neural circuit formation.
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Affiliation(s)
- Simon Xuan Chen
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
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16
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McFarlane S, Lom B. The Xenopus retinal ganglion cell as a model neuron to study the establishment of neuronal connectivity. Dev Neurobiol 2012; 72:520-36. [PMID: 21634016 DOI: 10.1002/dneu.20928] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Neurons receive inputs through their multiple branched dendrites and pass this information on to the next neuron via long axons, which branch within the target. The shape the neuron acquires is thus the key to its proper functioning in the neural circuit in which it participates. Both axons and dendrites grow in a directed fashion to their target partner neurons by responding to a large number of molecular cues in the milieu through which they extend. They then go through the process of synaptogenesis, first choosing a neuron on which to synapse, and then the appropriate subcellular location. How a neuron acquires its unique shape, establishes and modifies appropriate synaptic connectivity, and the molecular signals involved, are key questions in developmental neurobiology. Such questions of nervous system wiring are being pursued actively with a variety of different animal models and neuron types, each with its own unique advantages. Among these, the developing retinal ganglion cell (RGC) of the South African clawed frog, Xenopus laevis, has proven particularly fruitful for revealing the secrets of how axons and dendrites acquire their final morphology and connectivity. In this review, we describe how this system can be used to understand the multiple molecular events that instruct the incorporation of RGCs into the neural circuit that controls vision.
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Affiliation(s)
- Sarah McFarlane
- Department of Cell Biology and Anatomy, University of Calgary, Hotchkiss Brain Institute, Calgary, Alberta, Canada.
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17
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Udin SB. Binocular maps in Xenopus tectum: Visual experience and the development of isthmotectal topography. Dev Neurobiol 2012; 72:564-74. [PMID: 21674812 DOI: 10.1002/dneu.20933] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Xenopus frogs have a prominent binocular field that develops as a consequence of the migration of the eyes during the remodeling of the head during and after metamorphosis. In the optic tectum, a topographic representation of the ipsilateral eye develops during this same period. It is relayed indirectly, via the nucleus isthmi. In the early stages of binocular development, the topographic matching of the ipsilateral input to the retinotectal input from the contralateral eye is largely governed by chemical cues, but the ultimate determinant of the ipsilateral map is binocular visual input. Visual input is such a dominant factor that abnormal visual input resulting from unilateral eye rotation can induce isthmotectal axons to alter their trajectories dramatically, even shifting their terminal zones from one pole of the tectum to the other. This plasticity normally is high only during a 3-4-month critical period of late tadpole-early juvenile life, but the critical period can be extended indefinitely by dark-rearing. N-methyl-D-aspartate (NMDA) receptors are involved in this process; plasticity can be blocked or promoted by chronic treatment with NMDA antagonists or agonists, respectively. Cholinergic nicotinic receptors on retinotectal axons are likely to play an essential role as well. Modifications in the polysialylation of neural cell adhesion molecule are correlated with the state of plasticity. The circuitry underlying binocular plasticity is not yet fully understood but has proved not to be a simple convergence of ipsilateral and contralateral inputs onto the same targets.
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Affiliation(s)
- Susan B Udin
- Department of Physiology and Biophysics, State University of New York, Buffalo, NY 14214, USA.
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18
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Della Santina L, Wong ROL. A molecular link tethering neuronal responses with the past. Cell 2012; 151:9-11. [PMID: 23021210 DOI: 10.1016/j.cell.2012.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Neurons need to alter their response to a given stimulus over time in order for the animal to modify its behavior within a changing environment. Chen et al. now demonstrate that neuronal structure and function are altered coordinately by the history of the cell's activity through an unexpected molecular pathway.
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Affiliation(s)
- Luca Della Santina
- Department of Biological Structure, University of Washington, Seattle, 98195, USA
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Supernumerary formation of olfactory glomeruli induced by chronic odorant exposure: a constructivist expression of neural plasticity. PLoS One 2012; 7:e35358. [PMID: 22511987 PMCID: PMC3325210 DOI: 10.1371/journal.pone.0035358] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 03/14/2012] [Indexed: 12/18/2022] Open
Abstract
It is accepted that sensory experience instructs the remodelling of neuronal circuits during postnatal development, after their specification has occurred. The story is less clear with regard to the role of experience during the initial formation of neuronal circuits, whether prenatal or postnatal, since this process is now supposed to be primarily influenced by genetic determinants and spontaneous neuronal firing. Here we evaluated this last issue by examining the effect that postnatal chronic exposure to cognate odorants has on the formation of I7 and M72 glomeruli, iterated olfactory circuits that are formed before and after birth, respectively. We took advantage of double knock-in mice whose I7 and M72 primary afferents express green fluorescent protein and β-galactosidase, correspondingly. Our results revealed that postnatal odorant chronic exposure led to the formation of permanent supernumerary I7 and M72 glomeruli in a dose and time dependent manner. Glomeruli in exposed mice were formed within the same regions of olfactory bulb and occupy small space volumes compared to the corresponding single circuits in non-exposed mice. We suggest that local reorganization of the primary afferents could participate in the process of formation of supernumerary glomeruli. Overall, our results support that sensory experience indeed instructs the permanent formation of specific glomeruli in the mouse olfactory bulb by means of constructivist processes.
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20
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Richards BA, van Rheede JJ, Akerman CJ. Visuospatial information in the retinotectal system of xenopus before correct image formation by the developing eye. Dev Neurobiol 2012; 72:507-19. [DOI: 10.1002/dneu.20943] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Abstract
The mammalian cerebral cortex is characterized in vivo by irregular spontaneous activity, but how this ongoing dynamics affects signal processing and learning remains unknown. The associative plasticity rules demonstrated in vitro, mostly in silent networks, are based on the detection of correlations between presynaptic and postsynaptic activity and hence are sensitive to spontaneous activity and spurious correlations. Therefore, they cannot operate in realistic network states. Here, we present a new class of spike-timing-dependent plasticity learning rules with local floating plasticity thresholds, the slow dynamics of which account for metaplasticity. This novel algorithm is shown to both correctly predict homeostasis in synaptic weights and solve the problem of asymptotic stable learning in noisy states. It is shown to naturally encompass many other known types of learning rule, unifying them into a single coherent framework. The mixed presynaptic and postsynaptic dependency of the floating plasticity threshold is justified by a cascade of known molecular pathways, which leads to experimentally testable predictions.
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22
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Podgorski K, Dunfield D, Haas K. Functional clustering drives encoding improvement in a developing brain network during awake visual learning. PLoS Biol 2012; 10:e1001236. [PMID: 22253571 PMCID: PMC3254648 DOI: 10.1371/journal.pbio.1001236] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 11/21/2011] [Indexed: 11/18/2022] Open
Abstract
Sensory experience drives dramatic structural and functional plasticity in developing neurons. However, for single-neuron plasticity to optimally improve whole-network encoding of sensory information, changes must be coordinated between neurons to ensure a full range of stimuli is efficiently represented. Using two-photon calcium imaging to monitor evoked activity in over 100 neurons simultaneously, we investigate network-level changes in the developing Xenopus laevis tectum during visual training with motion stimuli. Training causes stimulus-specific changes in neuronal responses and interactions, resulting in improved population encoding. This plasticity is spatially structured, increasing tuning curve similarity and interactions among nearby neurons, and decreasing interactions among distant neurons. Training does not improve encoding by single clusters of similarly responding neurons, but improves encoding across clusters, indicating coordinated plasticity across the network. NMDA receptor blockade prevents coordinated plasticity, reduces clustering, and abolishes whole-network encoding improvement. We conclude that NMDA receptors support experience-dependent network self-organization, allowing efficient population coding of a diverse range of stimuli.
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Affiliation(s)
- Kaspar Podgorski
- Department of Cellular and Physiological Sciences and the Brain Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Derek Dunfield
- Center for Neuroeconomics, Sloan School of Management, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Kurt Haas
- Department of Cellular and Physiological Sciences and the Brain Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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23
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Siniatchkin M, Sendacki M, Moeller F, Wolff S, Jansen O, Siebner H, Stephani U. Abnormal Changes of Synaptic Excitability in Migraine with Aura. Cereb Cortex 2011; 22:2207-16. [DOI: 10.1093/cercor/bhr248] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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24
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Abstract
The three-layered primary olfactory (piriform) cortex is the largest component of the olfactory cortex. Sensory and intracortical inputs converge on principal cells in the anterior piriform cortex (aPC). We characterize organization principles of the sensory and intracortical microcircuitry of layer II and III principal cells in acute slices of rat aPC using laser-scanning photostimulation and fast two-photon population Ca(2+) imaging. Layer II and III principal cells are set up on a superficial-to-deep vertical axis. We found that the position on this axis correlates with input resistance and bursting behavior. These parameters scale with distinct patterns of incorporation into sensory and associative microcircuits, resulting in a converse gradient of sensory and intracortical inputs. In layer II, sensory circuits dominate superficial cells, whereas incorporation in intracortical circuits increases with depth. Layer III pyramidal cells receive more intracortical inputs than layer II pyramidal cells, but with an asymmetric dorsal offset. This microcircuit organization results in a diverse hybrid feedforward/recurrent network of neurons integrating varying ratios of intracortical and sensory input depending on a cell's position on the superficial-to-deep vertical axis. Since burstiness of spiking correlates with both the cell's location on this axis and its incorporation in intracortical microcircuitry, the neuronal output mode may encode a given cell's involvement in sensory versus associative processing.
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Visual experience-dependent maturation of correlated neuronal activity patterns in a developing visual system. J Neurosci 2011; 31:8025-36. [PMID: 21632924 DOI: 10.1523/jneurosci.5802-10.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The functional properties of neural circuits become increasingly robust over development. This allows circuits to optimize their output in response to a variety of input. However, it is not clear whether this optimization is a function of hardwired circuit elements, or whether it requires neural experience to develop. We performed rapid in vivo imaging of calcium signals from bulk-labeled neurons in the Xenopus laevis optic tectum to resolve the rapid spatiotemporal response properties of populations of developing tectal neurons in response to visual stimuli. We found that during a critical time in tectal development, network activity becomes increasingly robust, more correlated, and more synchronous. These developmental changes require normal visual input during development and are disrupted by NMDAR blockade. Our data show that visual activity and NMDAR activation are critical for the maturation of tectal network dynamics during visual system development.
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Gong LQ, He LJ, Dong ZY, Lu XH, Poo MM, Zhang XH. Postinduction requirement of NMDA receptor activation for late-phase long-term potentiation of developing retinotectal synapses in vivo. J Neurosci 2011; 31:3328-35. [PMID: 21368044 PMCID: PMC3096838 DOI: 10.1523/jneurosci.5936-10.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 12/21/2010] [Accepted: 12/29/2010] [Indexed: 11/21/2022] Open
Abstract
Spaced patterns of repetitive synaptic activation often result in a long-lasting, protein synthesis-dependent potentiation of synaptic transmission, known as late-phase long-term potentiation (L-LTP) that may serve as a substrate for long-term memory. Behavioral studies showed that posttraining blockade of NMDA subtype of the glutamate receptor (NMDAR) impaired long-term memory, although NMDAR activation is generally known to be required during LTP induction. In this study, we found that the establishment of L-LTP in vivo requires NMDAR activation within a critical time window after LTP induction. In the developing visual system of Xenopus laevis tadpole, L-LTP of retinotectal synapses could be induced by three episodes of theta burst stimulation (TBS) of the optic nerve with 5 min spacing ("spaced TBS"), but not by three TBS episodes applied en masse or spaced with intervals ≥10 min. Within a time window of ∼30 min after the spaced TBS, local perfusion of the tectum with NMDAR antagonist d-AP5 or Ca(2+)-chelator EGTA-AM impaired the establishment of L-LTP, indicating the requirement of postinduction activation of NMDAR/Ca(2+) signaling. Moreover, inhibiting spontaneous spiking activity in the tectum by local application of tetrodotoxin (TTX) prevented L-LTP when TTX was applied for 15 min immediately after the spaced TBS but not 1 h later, whereas the same postinduction TTX application in the retina had no effect. These findings offer new insights into the synaptic basis for the requirement of postlearning activation of NMDARs and point to the importance of postlearning spontaneous circuit activity in memory formation.
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Affiliation(s)
- Li-qin Gong
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200031, China, and
| | - Ling-jie He
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200031, China, and
| | - Zhi-yuan Dong
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200031, China, and
| | - Xiao-hui Lu
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200031, China, and
| | - Mu-ming Poo
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200031, China, and
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California 94720-3200
| | - Xiao-hui Zhang
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200031, China, and
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Evidence for a role of calcineurin in the development of retinocollicular fine topography. Neurosci Lett 2011; 487:47-52. [DOI: 10.1016/j.neulet.2010.09.071] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 09/27/2010] [Accepted: 09/27/2010] [Indexed: 11/24/2022]
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Tsui J, Schwartz N, Ruthazer ES. A developmental sensitive period for spike timing-dependent plasticity in the retinotectal projection. Front Synaptic Neurosci 2010; 2:13. [PMID: 21423499 PMCID: PMC3059707 DOI: 10.3389/fnsyn.2010.00013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 05/17/2010] [Indexed: 11/13/2022] Open
Abstract
The retinotectal projection in Xenopus laevis has been shown to exhibit correlation-based refinement of both anatomical and functional connectivity during development. Spike timing-dependent plasticity (STDP) is an appealing experimental model for correlation-based synaptic plasticity because, in contrast to plasticity induction paradigms using tetanic stimulation or sustained postsynaptic depolarization, its induction protocol more closely resembles natural physiological activity. In Xenopus tadpoles, where anatomical remodeling has been reported throughout much of the life of the animal, in vivo retinotectal STDP has only been examined under a limited set of experimental conditions. Using perforated-patch recordings of retina-evoked EPSCs in tectal neurons, we confirmed that repeatedly driving a retinotectal EPSP 5-10 ms prior to inducing an action potential in the postsynaptic cell, reliably produced timing-dependent long-term potentiation (t-LTP) of the retinotectal synapse in young wild type tadpoles (stages 41-44). At these stages, retinotectal timing-dependent long-term depression (t-LTD) also could be induced by evoking an EPSP to arrive 5-10 ms after an action potential in the tectal cell. However, retinotectal STDP using this standard protocol was limited to a developmental sensitive period, as we were unable to induce t-LTP or t-LTD after stage 44. Surprisingly, this STDP protocol also failed to induce reliable STDP in albino tadpoles at the early ages when it was effective in wild type pigmented animals. Nonetheless, low-frequency flashes to the eye produced a robust NMDA receptor-dependent retinotectal LTD in stage 47 albino tadpoles, demonstrating that the retinotectal synapse can nonetheless be modified in these animals using different plasticity paradigms.
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Affiliation(s)
- Jennifer Tsui
- Montreal Neurological Institute, McGill University Montreal, QC, Canada
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Richards BA, Aizenman CD, Akerman CJ. In vivo spike-timing-dependent plasticity in the optic tectum of Xenopus laevis. Front Synaptic Neurosci 2010; 2:7. [PMID: 21423493 PMCID: PMC3059697 DOI: 10.3389/fnsyn.2010.00007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 05/17/2010] [Indexed: 02/04/2023] Open
Abstract
Spike-timing-dependent plasticity (STDP) is found in vivo in a variety of systems and species, but the first demonstrations of in vivo STDP were carried out in the optic tectum of Xenopus laevis embryos. Since then, the optic tectum has served as an excellent experimental model for studying STDP in sensory systems, allowing researchers to probe the developmental consequences of this form of synaptic plasticity during early development. In this review, we will describe what is known about the role of STDP in shaping feed-forward and recurrent circuits in the optic tectum with a focus on the functional implications for vision. We will discuss both the similarities and differences between the optic tectum and mammalian sensory systems that are relevant to STDP. Finally, we will highlight the unique properties of the embryonic tectum that make it an important system for researchers who are interested in how STDP contributes to activity-dependent development of sensory computations.
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Dunfield D, Haas K. In vivo single-cell excitability probing of neuronal ensembles in the intact and awake developing Xenopus brain. Nat Protoc 2010; 5:841-8. [DOI: 10.1038/nprot.2010.10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Abstract
Metaplasticity refers to an activity-dependent regulation of the plastic state of neurons. In this issue of Neuron, Dunfield and Haas demonstrate that in intact developing brain circuits, specific patterns of visual stimulation drive functional plasticity of individual neurons with variable outcomes, predisposed by time-averaged postsynaptic activity recent to visual training.
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Affiliation(s)
- Sheng-zhi Wang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Huizhong Whit Tao
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
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