1
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Telliez C, De Sars V, Emiliani V, Ronzitti E. Descanned fast light targeting (deFLiT) two-photon optogenetics. BIOMEDICAL OPTICS EXPRESS 2023; 14:6222-6232. [PMID: 38420304 PMCID: PMC10898566 DOI: 10.1364/boe.499445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/11/2023] [Accepted: 09/25/2023] [Indexed: 03/02/2024]
Abstract
Two-photon light-targeting optogenetics allows controlling selected subsets of neurons with near single-cell resolution and high temporal precision. To push forward this approach, we recently proposed a fast light-targeting strategy (FLiT) to rapidly scan multiple holograms tiled on a spatial light modulator (SLM). This allowed generating sub-ms timely-controlled switch of light patterns enabling to reduce the power budget for multi-target excitation and increase the temporal precision for relative spike tuning in a circuit. Here, we modified the optical design of FLiT by including a de-scan unit (deFLiT) to keep the holographic illumination centered at the middle of the objective pupil independently of the position of the tiled hologram on the SLM. This enables enlarging the number of usable holograms and reaching extended on-axis excitation volumes, and therefore increasing even further the power gain and temporal precision of conventional FLiT.
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Affiliation(s)
- Cecile Telliez
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Vincent De Sars
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Valentina Emiliani
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Emiliano Ronzitti
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
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2
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Soldevila F, Moretti C, Nöbauer T, Sarafraz H, Vaziri A, Gigan S. Functional imaging through scattering medium via fluorescence speckle demixing and localization. OPTICS EXPRESS 2023; 31:21107-21117. [PMID: 37381218 PMCID: PMC10316750 DOI: 10.1364/oe.487768] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/04/2023] [Accepted: 05/28/2023] [Indexed: 06/30/2023]
Abstract
Recently, fluorescence-based optical techniques have emerged as a powerful tool to probe information in the mammalian brain. However, tissue heterogeneities prevent clear imaging of deep neuron bodies due to light scattering. While several up-to-date approaches based on ballistic light allow to retrieve information at shallow depths inside the brain, non-invasive localization and functional imaging at depth still remains a challenge. It was recently shown that functional signals from time-varying fluorescent emitters located behind scattering samples could be retrieved by using a matrix factorization algorithm. Here we show that the seemingly information-less, low-contrast fluorescent speckle patterns recovered by the algorithm can be used to locate each individual emitter, even in the presence of background fluorescence. We test our approach by imaging the temporal activity of large groups of fluorescent sources behind different scattering phantoms mimicking biological tissues, and through a brain slice with a thickness of ∼200 µm.
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Affiliation(s)
- F. Soldevila
- Laboratoire Kastler Brossel, ENS–Université PSL, CNRS, Sorbonne Université, College de France, 24 Rue Lhomond, F-75005 Paris, France
| | - C. Moretti
- Laboratoire Kastler Brossel, ENS–Université PSL, CNRS, Sorbonne Université, College de France, 24 Rue Lhomond, F-75005 Paris, France
| | - T. Nöbauer
- Laboratory of Neurotechnology and Biophysics, The Rockefeller University, New York, NY, USA
| | - H. Sarafraz
- Laboratory of Neurotechnology and Biophysics, The Rockefeller University, New York, NY, USA
| | - A. Vaziri
- Laboratory of Neurotechnology and Biophysics, The Rockefeller University, New York, NY, USA
- The Kavli Neural Systems Institute, The Rockefeller University, New York, NY, USA
| | - S. Gigan
- Laboratoire Kastler Brossel, ENS–Université PSL, CNRS, Sorbonne Université, College de France, 24 Rue Lhomond, F-75005 Paris, France
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3
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Yamaguchi A, Wu R, McNulty P, Karagyozov D, Mihovilovic Skanata M, Gershow M. Multi-neuronal recording in unrestrained animals with all acousto-optic random-access line-scanning two-photon microscopy. Front Neurosci 2023; 17:1135457. [PMID: 37389365 PMCID: PMC10303936 DOI: 10.3389/fnins.2023.1135457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 05/18/2023] [Indexed: 07/01/2023] Open
Abstract
To understand how neural activity encodes and coordinates behavior, it is desirable to record multi-neuronal activity in freely behaving animals. Imaging in unrestrained animals is challenging, especially for those, like larval Drosophila melanogaster, whose brains are deformed by body motion. A previously demonstrated two-photon tracking microscope recorded from individual neurons in freely crawling Drosophila larvae but faced limits in multi-neuronal recording. Here we demonstrate a new tracking microscope using acousto-optic deflectors (AODs) and an acoustic GRIN lens (TAG lens) to achieve axially resonant 2D random access scanning, sampling along arbitrarily located axial lines at a line rate of 70 kHz. With a tracking latency of 0.1 ms, this microscope recorded activities of various neurons in moving larval Drosophila CNS and VNC including premotor neurons, bilateral visual interneurons, and descending command neurons. This technique can be applied to the existing two-photon microscope to allow for fast 3D tracking and scanning.
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Affiliation(s)
- Akihiro Yamaguchi
- Department of Physics, New York University, New York, NY, United States
| | - Rui Wu
- Department of Physics, New York University, New York, NY, United States
| | - Paul McNulty
- Department of Physics, New York University, New York, NY, United States
| | - Doycho Karagyozov
- Department of Physics, New York University, New York, NY, United States
| | | | - Marc Gershow
- Department of Physics, New York University, New York, NY, United States
- Center for Neural Science, New York University, New York, NY, United States
- Neuroscience Institute, New York University, New York, NY, United States
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4
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Eremchev M, Roesel D, Dansette PM, Michailovas A, Roke S. High throughput wide field second harmonic imaging of giant unilamellar vesicles. Biointerphases 2023; 18:031202. [PMID: 37289033 DOI: 10.1116/6.0002640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 05/16/2023] [Indexed: 06/09/2023] Open
Abstract
Cell-sized giant unilamellar vesicles (GUVs) are an ideal tool for understanding lipid membrane structure and properties. Label-free spatiotemporal images of their membrane potential and structure would greatly aid the quantitative understanding of membrane properties. In principle, second harmonic imaging is a great tool to do so, but the low degree of spatial anisotropy that arises from a single membrane limits its application. Here, we advance the use of wide-field high throughput SH imaging by SH imaging with the use of ultrashort laser pulses. We achieve a throughput improvement of 78% of the maximum theoretical value and demonstrate subsecond image acquisition times. We show how the interfacial water intensity can be converted into a quantitative membrane potential map. Finally, for GUV imaging, we compare this type of nonresonant SH imaging to resonant SH imaging and two photon imaging using fluorophores.
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Affiliation(s)
- M Eremchev
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineerinsg (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - D Roesel
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineerinsg (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - P-M Dansette
- Ekspla Ltd., Savanoriu Ave. 237, LT-02300 Vilnius, Lithuania
| | - A Michailovas
- Ekspla Ltd., Savanoriu Ave. 237, LT-02300 Vilnius, Lithuania
- Center for Physical Sciences and Technology, Savanoriu Ave. 231, LT-02300 Vilnius, Lithuania
| | - S Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineerinsg (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering (IMX), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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5
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Accanto N, Blot FGC, Lorca-Cámara A, Zampini V, Bui F, Tourain C, Badt N, Katz O, Emiliani V. A flexible two-photon fiberscope for fast activity imaging and precise optogenetic photostimulation of neurons in freely moving mice. Neuron 2023; 111:176-189.e6. [PMID: 36395773 DOI: 10.1016/j.neuron.2022.10.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 07/28/2022] [Accepted: 10/19/2022] [Indexed: 11/17/2022]
Abstract
We developed a flexible two-photon microendoscope (2P-FENDO) capable of all-optical brain investigation at near cellular resolution in freely moving mice. The system performs fast two-photon (2P) functional imaging and 2P holographic photostimulation of single and multiple cells using axially confined extended spots. Proof-of-principle experiments were performed in freely moving mice co-expressing jGCaMP7s and the opsin ChRmine in the visual or barrel cortex. On a field of view of 250 μm in diameter, we demonstrated functional imaging at a frame rate of up to 50 Hz and precise photostimulation of selected groups of cells. With the capability to simultaneously image and control defined neuronal networks in freely moving animals, 2P-FENDO will enable a precise investigation of neuronal functions in the brain during naturalistic behaviors.
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Affiliation(s)
- Nicolò Accanto
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - François G C Blot
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | | | - Valeria Zampini
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Florence Bui
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Christophe Tourain
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Noam Badt
- Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ori Katz
- Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Valentina Emiliani
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
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6
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Lin J, Cheng Z, Yang G, Cui M. Optical gearbox enabled versatile multiscale high-throughput multiphoton functional imaging. Nat Commun 2022; 13:6564. [PMID: 36323707 PMCID: PMC9630539 DOI: 10.1038/s41467-022-34472-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 10/19/2022] [Indexed: 11/05/2022] Open
Abstract
To understand the function and mechanism of biological systems, it is crucial to observe the cellular dynamics at high spatiotemporal resolutions within live animals. The recent advances in genetically encoded function indicators have significantly improved the response rate to a near millisecond time scale. However, the widely employed in vivo imaging systems often lack the temporal solution to capture the fast biological dynamics. To broadly enable the capability of high-speed in vivo deep-tissue imaging, we developed an optical gearbox. As an add-on module, the optical gearbox can convert the common multiphoton imaging systems for versatile multiscale high-throughput imaging applications. In this work, we demonstrate in vivo 2D and 3D function imaging in mammalian brains at frame rates ranging from 50 to 1000 Hz. The optical gearbox's versatility and compatibility with the widely employed imaging components will be highly valuable to a variety of deep tissue imaging applications.
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Affiliation(s)
- Jianian Lin
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Bindley Bioscience Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Zongyue Cheng
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Bindley Bioscience Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Guang Yang
- Department of Anesthesiology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Meng Cui
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA.
- Bindley Bioscience Center, Purdue University, West Lafayette, IN, 47907, USA.
- Department of Biology, Purdue University, West Lafayette, IN, 47907, USA.
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7
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Cai Y, Wu J, Dai Q. Review on data analysis methods for mesoscale neural imaging in vivo. NEUROPHOTONICS 2022; 9:041407. [PMID: 35450225 PMCID: PMC9010663 DOI: 10.1117/1.nph.9.4.041407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/23/2022] [Indexed: 06/14/2023]
Abstract
Significance: Mesoscale neural imaging in vivo has gained extreme popularity in neuroscience for its capacity of recording large-scale neurons in action. Optical imaging with single-cell resolution and millimeter-level field of view in vivo has been providing an accumulated database of neuron-behavior correspondence. Meanwhile, optical detection of neuron signals is easily contaminated by noises, background, crosstalk, and motion artifacts, while neural-level signal processing and network-level coordinate are extremely complicated, leading to laborious and challenging signal processing demands. The existing data analysis procedure remains unstandardized, which could be daunting to neophytes or neuroscientists without computational background. Aim: We hope to provide a general data analysis pipeline of mesoscale neural imaging shared between imaging modalities and systems. Approach: We divide the pipeline into two main stages. The first stage focuses on extracting high-fidelity neural responses at single-cell level from raw images, including motion registration, image denoising, neuron segmentation, and signal extraction. The second stage focuses on data mining, including neural functional mapping, clustering, and brain-wide network deduction. Results: Here, we introduce the general pipeline of processing the mesoscale neural images. We explain the principles of these procedures and compare different approaches and their application scopes with detailed discussions about the shortcomings and remaining challenges. Conclusions: There are great challenges and opportunities brought by the large-scale mesoscale data, such as the balance between fidelity and efficiency, increasing computational load, and neural network interpretability. We believe that global circuits on single-neuron level will be more extensively explored in the future.
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Affiliation(s)
- Yeyi Cai
- Tsinghua University, Department of Automation, Beijing, China
| | - Jiamin Wu
- Tsinghua University, Department of Automation, Beijing, China
| | - Qionghai Dai
- Tsinghua University, Department of Automation, Beijing, China
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8
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de Coene Y, Jooken S, Deschaume O, Van Steenbergen V, Vanden Berghe P, Van den Haute C, Baekelandt V, Callewaert G, Van Cleuvenbergen S, Verbiest T, Bartic C, Clays K. Label-Free Imaging of Membrane Potentials by Intramembrane Field Modulation, Assessed by Second Harmonic Generation Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200205. [PMID: 35355419 DOI: 10.1002/smll.202200205] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/03/2022] [Indexed: 06/14/2023]
Abstract
Optical interrogation of cellular electrical activity has proven itself essential for understanding cellular function and communication in complex networks. Voltage-sensitive dyes are important tools for assessing excitability but these highly lipophilic sensors may affect cellular function. Label-free techniques offer a major advantage as they eliminate the need for these external probes. In this work, it is shown that endogenous second-harmonic generation (SHG) from live cells is highly sensitive to changes in transmembrane potential (TMP). Simultaneous electrophysiological control of a living human embryonic kidney (HEK293T) cell, through a whole-cell voltage-clamp reveals a linear relation between the SHG intensity and membrane voltage. The results suggest that due to the high ionic strengths and fast optical response of biofluids, membrane hydration is not the main contributor to the observed field sensitivity. A conceptual framework is further provided that indicates that the SHG voltage sensitivity reflects the electric field within the biological asymmetric lipid bilayer owing to a nonzero χeff(2) tensor. Changing the TMP without surface modifications such as electrolyte screening offers high optical sensitivity to membrane voltage (≈40% per 100 mV), indicating the power of SHG for label-free read-out. These results hold promise for the design of a non-invasive label-free read-out tool for electrogenic cells.
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Affiliation(s)
- Yovan de Coene
- Laboratory of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Celestijnenlaan 200D, Leuven, 3001, Belgium
| | - Stijn Jooken
- Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, Leuven, 3001, Belgium
| | - Olivier Deschaume
- Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, Leuven, 3001, Belgium
| | - Valérie Van Steenbergen
- Laboratory for Enteric NeuroScience (LENS), TAGRID, Department of Chronic Diseases Metabolism and Ageing, Ku Leuven, ON I Herestraat 49, Leuven, 3000, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), TAGRID, Department of Chronic Diseases Metabolism and Ageing, Ku Leuven, ON I Herestraat 49, Leuven, 3000, Belgium
| | - Chris Van den Haute
- Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, Ku Leuven, RK-Herestraat 49, Leuven, 3000, Belgium
| | - Veerle Baekelandt
- Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, Ku Leuven, RK-Herestraat 49, Leuven, 3000, Belgium
| | - Geert Callewaert
- Department of Cellular and Molecular Medicine, Ku Leuven, KULAK Kortrijk Campus, Etienne Sabbelaan 53, Kortrijk, 8500, Belgium
| | - Stijn Van Cleuvenbergen
- Laboratory of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Celestijnenlaan 200D, Leuven, 3001, Belgium
| | - Thierry Verbiest
- Laboratory of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Celestijnenlaan 200D, Leuven, 3001, Belgium
| | - Carmen Bartic
- Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, Leuven, 3001, Belgium
| | - Koen Clays
- Laboratory of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Celestijnenlaan 200D, Leuven, 3001, Belgium
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9
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Ricci P, Marchetti M, Sorelli M, Turrini L, Resta F, Gavryusev V, de Vito G, Sancataldo G, Vanzi F, Silvestri L, Pavone FS. Power-effective scanning with AODs for 3D optogenetic applications. JOURNAL OF BIOPHOTONICS 2022; 15:e202100256. [PMID: 35000289 DOI: 10.1002/jbio.202100256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 05/18/2023]
Abstract
Two-photon (2P) excitation is a cornerstone approach widely employed in neuroscience microscopy for deep optical access and sub-micrometric-resolution light targeting into the brain. However, besides structural and functional imaging, 2P optogenetic stimulations are less routinary, especially in 3D. This is because of the adopted scanning systems, often feebly effective, slow and mechanically constricted. Faster illumination can be achieved through acousto-optic deflectors (AODs) although their applicability to large volumes excitation has been limited by large efficiency drop along the optical axis. Here, we present a new AOD-based scheme for 2P 3D scanning that improves the power delivery between different illumination planes. We applied this approach to photostimulate an optogenetic actuator in zebrafish larvae, demonstrating the method efficiency observing increased activity responses and uniform activation probabilities from neuronal clusters addressed in the volume. This novel driving scheme can open to new AOD applications in neuroscience, allowing more effective 3D interrogation in large neuronal networks.
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Affiliation(s)
- Pietro Ricci
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Physics and Astronomy, University of Florence, Florence
| | | | - Michele Sorelli
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Physics and Astronomy, University of Florence, Florence
| | - Lapo Turrini
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Physics and Astronomy, University of Florence, Florence
| | - Francesco Resta
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Physics and Astronomy, University of Florence, Florence
| | - Vladislav Gavryusev
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Physics and Astronomy, University of Florence, Florence
| | - Giuseppe de Vito
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | | | - Francesco Vanzi
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Biology, University of Florence, Florence, Italy
| | - Ludovico Silvestri
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Physics and Astronomy, University of Florence, Florence
- National Institute of Optics, Florence, Italy
| | - Francesco Saverio Pavone
- European Laboratory for Non-Linear Spectroscopy, Florence
- Department of Physics and Astronomy, University of Florence, Florence
- L4T-Light4Tech, Florence, Italy
- National Institute of Optics, Florence, Italy
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10
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Daria VR, Castañares ML, Bachor HA. Spatio-temporal parameters for optical probing of neuronal activity. Biophys Rev 2021; 13:13-33. [PMID: 33747244 PMCID: PMC7930150 DOI: 10.1007/s12551-021-00780-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 01/01/2021] [Indexed: 12/28/2022] Open
Abstract
The challenge to understand the complex neuronal circuit functions in the mammalian brain has brought about a revolution in light-based neurotechnologies and optogenetic tools. However, while recent seminal works have shown excellent insights on the processing of basic functions such as sensory perception, memory, and navigation, understanding more complex brain functions is still unattainable with current technologies. We are just scratching the surface, both literally and figuratively. Yet, the path towards fully understanding the brain is not totally uncertain. Recent rapid technological advancements have allowed us to analyze the processing of signals within dendritic arborizations of single neurons and within neuronal circuits. Understanding the circuit dynamics in the brain requires a good appreciation of the spatial and temporal properties of neuronal activity. Here, we assess the spatio-temporal parameters of neuronal responses and match them with suitable light-based neurotechnologies as well as photochemical and optogenetic tools. We focus on the spatial range that includes dendrites and certain brain regions (e.g., cortex and hippocampus) that constitute neuronal circuits. We also review some temporal characteristics of some proteins and ion channels responsible for certain neuronal functions. With the aid of the photochemical and optogenetic markers, we can use light to visualize the circuit dynamics of a functioning brain. The challenge to understand how the brain works continue to excite scientists as research questions begin to link macroscopic and microscopic units of brain circuits.
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Affiliation(s)
- Vincent R. Daria
- Research School of Physics, The Australian National University, Canberra, Australia
- John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | | | - Hans-A. Bachor
- Research School of Physics, The Australian National University, Canberra, Australia
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11
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T-tubule remodeling in human hypertrophic cardiomyopathy. J Muscle Res Cell Motil 2020; 42:305-322. [PMID: 33222034 PMCID: PMC8332592 DOI: 10.1007/s10974-020-09591-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/22/2020] [Indexed: 11/17/2022]
Abstract
The highly organized transverse T-tubule membrane system represents the ultrastructural substrate for excitation–contraction coupling in ventricular myocytes. While the architecture and function of T-tubules have been well described in animal models, there is limited morpho-functional data on T-tubules in human myocardium. Hypertrophic cardiomyopathy (HCM) is a primary disease of the heart muscle, characterized by different clinical presentations at the various stages of its progression. Most HCM patients, indeed, show a compensated hypertrophic disease (“non-failing hypertrophic phase”), with preserved left ventricular function, and only a small subset of individuals evolves into heart failure (“end stage HCM”). In terms of T-tubule remodeling, the “end-stage” disease does not differ from other forms of heart failure. In this review we aim to recapitulate the main structural features of T-tubules during the “non-failing hypertrophic stage” of human HCM by revisiting data obtained from human myectomy samples. Moreover, by comparing pathological changes observed in myectomy samples with those introduced by acute (experimentally induced) detubulation, we discuss the role of T-tubular disruption as a part of the complex excitation–contraction coupling remodeling process that occurs during disease progression. Lastly, we highlight how T-tubule morpho-functional changes may be related to patient genotype and we discuss the possibility of a primitive remodeling of the T-tubule system in rare HCM forms associated with genes coding for proteins implicated in T-tubule structural integrity, formation and maintenance.
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12
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Deguchi T, Bianchini P, Palazzolo G, Oneto M, Diaspro A, Duocastella M. Volumetric Lissajous confocal microscopy with tunable spatiotemporal resolution. BIOMEDICAL OPTICS EXPRESS 2020; 11:6293-6310. [PMID: 33282491 PMCID: PMC7687945 DOI: 10.1364/boe.400777] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/06/2020] [Accepted: 10/06/2020] [Indexed: 05/29/2023]
Abstract
Dynamic biological systems present challenges to existing three-dimensional (3D) optical microscopes because of their continuous temporal and spatial changes. Most techniques are rigid in adapting the acquisition parameters over time, as in confocal microscopy, where a laser beam is sequentially scanned at a predefined spatial sampling rate and pixel dwell time. Such lack of tunability forces a user to provide scan parameters, which may not be optimal, based on the best assumption before an acquisition starts. Here, we developed volumetric Lissajous confocal microscopy to achieve unsurpassed 3D scanning speed with a tunable sampling rate. The system combines an acoustic liquid lens for continuous axial focus translation with a resonant scanning mirror. Accordingly, the excitation beam follows a dynamic Lissajous trajectory enabling sub-millisecond acquisitions of image series containing 3D information at a sub-Nyquist sampling rate. By temporal accumulation and/or advanced interpolation algorithms, the volumetric imaging rate is selectable using a post-processing step at the desired spatiotemporal resolution for events of interest. We demonstrate multicolor and calcium imaging over volumes of tens of cubic microns with 3D acquisition speeds of 30 Hz and frame rates up to 5 kHz.
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Affiliation(s)
- Takahiro Deguchi
- Nanoscopy & NIC@IIT, Center for Human Technologies, Istituto Italiano di Tecnologia, via E. Melen 83B, 16152 Genoa, Italy
| | - Paolo Bianchini
- Nanoscopy & NIC@IIT, Center for Human Technologies, Istituto Italiano di Tecnologia, via E. Melen 83B, 16152 Genoa, Italy
| | - Gemma Palazzolo
- Enhanced Regenerative Medicine, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genoa, Italy
| | - Michele Oneto
- Nanoscopy & NIC@IIT, Center for Human Technologies, Istituto Italiano di Tecnologia, via E. Melen 83B, 16152 Genoa, Italy
| | - Alberto Diaspro
- Nanoscopy & NIC@IIT, Center for Human Technologies, Istituto Italiano di Tecnologia, via E. Melen 83B, 16152 Genoa, Italy
- Dipartimento di Fisica, Universita di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
| | - Martí Duocastella
- Nanoscopy & NIC@IIT, Center for Human Technologies, Istituto Italiano di Tecnologia, via E. Melen 83B, 16152 Genoa, Italy
- Departament de Física Aplicada, Universitat de Barcelona, C/Marti i Franques 1, 08028 Barcelona, Spain
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13
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Schmidt E, Oheim M. Infrared Excitation Induces Heating and Calcium Microdomain Hyperactivity in Cortical Astrocytes. Biophys J 2020; 119:2153-2165. [PMID: 33130118 DOI: 10.1016/j.bpj.2020.10.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 10/01/2020] [Accepted: 10/07/2020] [Indexed: 11/16/2022] Open
Abstract
Unraveling how neural networks process and represent sensory information and how these cellular signals instruct behavioral output is a main goal in neuroscience. Two-photon activation of optogenetic actuators and calcium (Ca2+) imaging with genetically encoded indicators allow, respectively, the all-optical stimulation and readout of activity from genetically identified cell populations. However, these techniques locally expose the brain to high near-infrared light doses, raising the concern of light-induced adverse effects on the biology under study. Combining 2P imaging of Ca2+ transients in GCaMP6f-expressing cortical astrocytes and unbiased machine-based event detection, we demonstrate the subtle build-up of aberrant microdomain Ca2+ transients in the fine astroglial processes that depended on the average rather than peak laser power. Illumination conditions routinely being used in biological 2P microscopy (920-nm excitation, ∼100-fs, and ∼10 mW average power) increased the frequency of microdomain Ca2+ events but left their amplitude, area, and duration largely unchanged. Ca2+ transients in the otherwise silent soma were secondary to this peripheral hyperactivity that occurred without overt morphological damage. Continuous-wave (nonpulsed) 920-nm illumination at the same average power was as damaging as femtosecond pulses, unraveling the dominance of a heating-mediated damage mechanism. In an astrocyte-specific inositol 3-phosphate receptor type-2 knockout mouse, near-infrared light-induced Ca2+ microdomains persisted in the small processes, underpinning their resemblance to physiological inositol 3-phosphate receptor type-2-independent Ca2+ signals, whereas somatic hyperactivity was abolished. We conclude that, contrary to what has generally been believed in the field, shorter pulses and lower average power can help to alleviate damage and allow for longer recording windows at 920 nm.
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Affiliation(s)
- Elke Schmidt
- Université de Paris, SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Paris, France
| | - Martin Oheim
- Université de Paris, SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Paris, France.
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14
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Two-Photon Voltage Imaging of Spontaneous Activity from Multiple Neurons Reveals Network Activity in Brain Tissue. iScience 2020; 23:101363. [PMID: 32717641 PMCID: PMC7393527 DOI: 10.1016/j.isci.2020.101363] [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: 02/13/2020] [Revised: 04/07/2020] [Accepted: 07/09/2020] [Indexed: 11/23/2022] Open
Abstract
Recording the electrical activity of multiple neurons simultaneously would greatly facilitate studies on the function of neuronal circuits. The combination of the fast scanning by random-access multiphoton microscopy (RAMP) and the latest two-photon-compatible high-performance fluorescent genetically encoded voltage indicators (GEVIs) has enabled action potential detection in deep layers in in vivo brain. However, neuron connectivity analysis on optically recorded action potentials from multiple neurons in brain tissue has yet to be achieved. With high expression of a two-photon-compatible GEVI, ASAP3, via in utero electroporation and RAMP, we achieved voltage recording of spontaneous activities from multiple neurons in brain slice. We provide evidence for the developmental changes in intralaminar horizontal connections in somatosensory cortex layer 2/3 with a greater sensitivity than calcium imaging. This method thus enables investigation of neuronal network connectivity at the cellular resolution in brain tissue.
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15
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Functional interrogation of neural circuits with virally transmitted optogenetic tools. J Neurosci Methods 2020; 345:108905. [PMID: 32795553 DOI: 10.1016/j.jneumeth.2020.108905] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 08/03/2020] [Accepted: 08/06/2020] [Indexed: 12/12/2022]
Abstract
The vertebrate brain comprises a plethora of cell types connected by intertwined pathways. Optogenetics enriches the neuroscientific tool set for disentangling these neuronal circuits in a manner which exceeds the spatio-temporal precision of previously existing techniques. Technically, optogenetics can be divided in three types of optical and genetic combinations: (1) it is primarily understood as the manipulation of the activity of genetically modified cells (typically neurons) with light, i.e. optical actuators. (2) A second combination refers to visualizing the activity of genetically modified cells (again typically neurons), i.e. optical sensors. (3) A completely different interpretation of optogenetics refers to the light activated expression of a genetically induced construct. Here, we focus on the first two types of optogenetics, i.e. the optical actuators and sensors in an attempt to give an overview into the topic. We first cover methods to express opsins into neurons and introduce strategies of targeting specific neuronal populations in different animal species. We then summarize combinations of optogenetics with behavioral read out and neuronal imaging. Finally, we give an overview of the current state-of-the-art and an outlook on future perspectives.
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16
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Griffiths VA, Valera AM, Lau JY, Roš H, Younts TJ, Marin B, Baragli C, Coyle D, Evans GJ, Konstantinou G, Koimtzis T, Nadella KMNS, Punde SA, Kirkby PA, Bianco IH, Silver RA. Real-time 3D movement correction for two-photon imaging in behaving animals. Nat Methods 2020; 17:741-748. [PMID: 32483335 PMCID: PMC7370269 DOI: 10.1038/s41592-020-0851-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 04/28/2020] [Indexed: 11/09/2022]
Abstract
Two-photon microscopy is widely used to investigate brain function across multiple spatial scales. However, measurements of neural activity are compromised by brain movement in behaving animals. Brain motion-induced artifacts are typically corrected using post hoc processing of two-dimensional images, but this approach is slow and does not correct for axial movements. Moreover, the deleterious effects of brain movement on high-speed imaging of small regions of interest and photostimulation cannot be corrected post hoc. To address this problem, we combined random-access three-dimensional (3D) laser scanning using an acousto-optic lens and rapid closed-loop field programmable gate array processing to track 3D brain movement and correct motion artifacts in real time at up to 1 kHz. Our recordings from synapses, dendrites and large neuronal populations in behaving mice and zebrafish demonstrate real-time movement-corrected 3D two-photon imaging with submicrometer precision.
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Affiliation(s)
- Victoria A Griffiths
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Antoine M Valera
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Joanna Yn Lau
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Hana Roš
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Thomas J Younts
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Bóris Marin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
- Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, São Bernardo do Campo, Brazil
| | - Chiara Baragli
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
- , Paris, France
| | - Diccon Coyle
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Geoffrey J Evans
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
- Department of Engineering, Sencon (UK) Ltd., Droitwich, UK
| | - George Konstantinou
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
- The Francis Crick Institute, London, UK
| | - Theo Koimtzis
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
- Optical Metrology Service, Stansted, UK
| | | | - Sameer A Punde
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Paul A Kirkby
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Isaac H Bianco
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - R Angus Silver
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
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17
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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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18
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Allende Motz AM, Czerski J, Adams DE, Durfee C, Bartels R, Field J, Hoy CL, Squier J. Two-dimensional random access multiphoton spatial frequency modulated imaging. OPTICS EXPRESS 2020; 28:405-424. [PMID: 32118968 PMCID: PMC7053501 DOI: 10.1364/oe.378460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 12/15/2019] [Accepted: 12/16/2019] [Indexed: 05/17/2023]
Abstract
Spatial frequency modulated imaging (SPIFI) enables the use of an extended excitation source for linear and nonlinear imaging with single element detection. To date, SPIFI has only been used with fixed excitation source geometries. Here, we explore the potential for the SPIFI method when a spatial light modulator (SLM) is used to program the excitation source, opening the door to a more versatile, random access imaging environment. In addition, an in-line, quantitative pulse compensation and measurement scheme is demonstrated using a new technique, spectral phase and amplitude retrieval and compensation (SPARC). This enables full characterization of the light exposure conditions at the focal plane of the random access imaging system, an important metric for optimizing, and reporting imaging conditions within specimens.
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Affiliation(s)
- Alyssa M. Allende Motz
- Department of Physics, Colorado School of Mines, 1532 Illinois St., Golden, CO 80401, USA
| | - John Czerski
- Department of Physics, Colorado School of Mines, 1532 Illinois St., Golden, CO 80401, USA
| | - Daniel E. Adams
- Department of Physics, Colorado School of Mines, 1532 Illinois St., Golden, CO 80401, USA
| | - Charles Durfee
- Department of Physics, Colorado School of Mines, 1532 Illinois St., Golden, CO 80401, USA
| | - Randy Bartels
- Department of Electrical Engineering, Colorado State University, 400 Isotope Dr., Ft. Collins, CO 80523, USA
- Department of Biomedical Engineering, and Molecular Biology, Colorado State University, 400 Isotope Dr., Ft. Collins, CO 80523, USA
| | - Jeff Field
- Department of Electrical Engineering, Colorado State University, 400 Isotope Dr., Ft. Collins, CO 80523, USA
- Department of Biomedical Engineering, and Molecular Biology, Colorado State University, 400 Isotope Dr., Ft. Collins, CO 80523, USA
- Microscope Imaging Network Foundation Core Facility, Colorado State University, 400 Isotope Dr., Ft. Collins, CO 80523, USA
| | | | - Jeff Squier
- Department of Physics, Colorado School of Mines, 1532 Illinois St., Golden, CO 80401, USA
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19
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Johnson C, Exell J, Kuo J, Welsher K. Continuous focal translation enhances rate of point-scan volumetric microscopy. OPTICS EXPRESS 2019; 27:36241-36258. [PMID: 31873407 PMCID: PMC7046036 DOI: 10.1364/oe.27.036241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Two-Photon Laser-Scanning Microscopy is a powerful tool for exploring biological structure and function due to its ability to optically section through a sample with a tight focus. While it is possible to obtain 3D image stacks by moving a stage, this per-frame imaging process is time consuming. Here, we present a method for an easy-to-implement and inexpensive modification of an existing two-photon microscope to rapidly image in 3D using an electrically tunable lens to create a tessellating scan pattern which repeats with the volume rate. Using appropriate interpolating algorithms, the volumetric imaging rate can be increased by a factor up to four-fold. This capability provides the expansion of the two-photon microscope into the third dimension for faster volumetric imaging capable of visualizing dynamics on timescales not achievable by traditional stage-stack methods.
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20
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Lecoq J, Orlova N, Grewe BF. Wide. Fast. Deep: Recent Advances in Multiphoton Microscopy of In Vivo Neuronal Activity. J Neurosci 2019; 39:9042-9052. [PMID: 31578235 PMCID: PMC6855689 DOI: 10.1523/jneurosci.1527-18.2019] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 09/27/2019] [Accepted: 09/27/2019] [Indexed: 01/04/2023] Open
Abstract
Multiphoton microscopy (MPM) has emerged as one of the most powerful and widespread technologies to monitor the activity of neuronal networks in awake, behaving animals over long periods of time. MPM development spanned across decades and crucially depended on the concurrent improvement of calcium indicators that report neuronal activity as well as surgical protocols, head fixation approaches, and innovations in optics and microscopy technology. Here we review the last decade of MPM development and highlight how in vivo imaging has matured and diversified, making it now possible to concurrently monitor thousands of neurons across connected brain areas or, alternatively, small local networks with sampling rates in the kilohertz range. This review includes different laser scanning approaches, such as multibeam technologies as well as recent developments to image deeper into neuronal tissues using new, long-wavelength laser sources. As future development will critically depend on our ability to resolve and discriminate individual neuronal spikes, we will also describe a simple framework that allows performing quantitative comparisons between the reviewed MPM instruments. Finally, we provide our own opinion on how the most recent MPM developments can be leveraged at scale to enable the next generation of discoveries in brain function.
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Affiliation(s)
- Jérôme Lecoq
- Allen Institute for Brain Science, Seattle 98109, Washington,
| | - Natalia Orlova
- Allen Institute for Brain Science, Seattle 98109, Washington
| | - Benjamin F Grewe
- Institute of Neuroinformatics, UZH and ETH Zurich, Zurich 8057, Switzerland
- Department of Electrical Engineering and Information Technology, ETH Zurich, Zurich 8092, Switzerland, and
- Faculty of Sciences, University of Zurich, Zurich 8057, Switzerland
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21
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Narrowly Confined and Glomerulus-Specific Onset Latencies of Odor-Evoked Calcium Transients in the Juxtaglomerular Cells of the Mouse Main Olfactory Bulb. eNeuro 2019; 6:eN-NWR-0387-18. [PMID: 30834302 PMCID: PMC6397951 DOI: 10.1523/eneuro.0387-18.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 02/01/2019] [Accepted: 02/05/2019] [Indexed: 12/04/2022] Open
Abstract
Odor information is transmitted from olfactory sensory neurons to principal neurons at the glomeruli of the olfactory bulb. The intraglomerular neuronal circuit also includes hundreds of interneurons referred to as juxtaglomerular (JG) cells. Stimulus selectivity is well correlated among many JG cells that are associated with the same glomerulus, consistent with their highly homogeneous sensory inputs. However, much less is known about the temporal aspects of their activity, including the temporal coordination of their odor-evoked responses. As many JG cells within a glomerular module respond to the same stimulus, the extent to which their activity is temporally aligned will affect the temporal profile of their population inhibitory inputs. Using random-access high-speed two-photon microscopy, we recorded the odor-evoked calcium transients of mouse JG cells and compared the onset latency and rise time among neurons putatively associated with the same and different glomeruli. Whereas the overall onset latencies of odor-evoked transients were distributed across a ∼150 ms time window, those from cells putatively associated with the same glomerulus were confined to a much narrower window of several tens of milliseconds. This result suggests that onset latency primarily depends on the associated glomerulus. We also observed glomerular specificity in the rise time. The glomerulus-specific temporal pattern of odor-evoked activity implies that the temporal patterns of inputs from the intraglomerular circuit are unique to individual glomerulus–odor pairs, which may contribute to efficient shaping of the temporal pattern of activity in the principal neurons.
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22
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Chong EZ, Panniello M, Barreiros I, Kohl MM, Booth MJ. Quasi-simultaneous multiplane calcium imaging of neuronal circuits. BIOMEDICAL OPTICS EXPRESS 2019; 10:267-282. [PMID: 30775099 PMCID: PMC6363184 DOI: 10.1364/boe.10.000267] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/12/2018] [Accepted: 11/12/2018] [Indexed: 06/09/2023]
Abstract
Two-photon excitation fluorescence microscopy is widely used to study the activity of neuronal circuits. However, the fast imaging is typically constrained to a single lateral plane for a standard microscope design. Given that cortical neuronal networks in a mouse brain are complex three-dimensional structures organised in six histologically defined layers which extend over many hundreds of micrometres, there is a strong demand for microscope systems that can record neuronal signalling in volumes. Henceforth, we developed a quasi-simultaneous multiplane imaging technique combining an acousto-optic deflector and static remote focusing to provide fast imaging of neurons from different axial positions inside the cortical layers without the need for mechanical disturbance of either the objective lens or the specimen. The hardware and the software are easily adaptable to existing two-photon microscopes. Here, we demonstrated that our imaging method can record, at high speed and high image contrast, the calcium dynamics of neurons in two different imaging planes separated axially with the in-focus and the refocused planes 120 µm and 250 µm below the brain surface respectively.
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Affiliation(s)
- Ee Zhuan Chong
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ, UK
| | - Mariangela Panniello
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, UK
| | - Inês Barreiros
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, UK
| | - Michael M Kohl
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, UK
| | - Martin J Booth
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ, UK
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23
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Scardigli M, Ferrantini C, Crocini C, Pavone FS, Sacconi L. Interplay Between Sub-Cellular Alterations of Calcium Release and T-Tubular Defects in Cardiac Diseases. Front Physiol 2018; 9:1474. [PMID: 30410446 PMCID: PMC6209824 DOI: 10.3389/fphys.2018.01474] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/28/2018] [Indexed: 12/19/2022] Open
Abstract
Asynchronous Ca2+ release promotes non-homogeneous myofilament activation, leading to mechanical dysfunction, as well as initiation of propagated calcium waves and arrhythmias. Recent advances in microscopy techniques have allowed for optical recordings of local Ca2+ fluxes and action potentials from multiple sub-cellular domains within cardiac cells with unprecedented spatial and temporal resolution. Since then, sub-cellular local information of the spatio-temporal relationship between Ca2+ release and action potential propagation have been unlocked, providing novel mechanistic insights in cardiac excitation-contraction coupling (ECC). Here, we review the promising perspectives arouse from repeatedly probing Ca2+ release at the same sub-cellular location while simultaneously probing multiple locations at the same time within a single cardiac cell. We also compare the results obtained in three different rodent models of cardiac diseases, highlighting disease-specific mechanisms. Slower local Ca2+ release has been observed in regions with defective action potential conduction in diseased cardiac cells. Moreover, significant increment of Ca2+ variability (both in time and in space) has been found in diseased cardiac cells but does not directly correlate with local electrical defects nor with the degree of structural aberrations of the cellular membrane system, suggesting a role for other players of the ECC machinery. We finally explore exciting opportunities provided by the technology for studying different cardiomyocyte populations, as well as for dissecting the mechanisms responsible for subcellular spatio-temporal variability of Ca2+ release.
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Affiliation(s)
- Marina Scardigli
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy
| | - Cecilia Ferrantini
- European Laboratory for Non-Linear Spectroscopy, Florence, Italy.,Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Claudia Crocini
- Department of Molecular, Cellular, and Developmental Biology & BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, United States
| | - Francesco S Pavone
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy.,Department of Physics and Astronomy, University of Florence, Florence, Italy
| | - Leonardo Sacconi
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy
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24
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Heidarinejad M, Nakamura H, Inoue T. Stimulation-induced changes in diffusion and structure of calmodulin and calmodulin-dependent protein kinase II proteins in neurons. Neurosci Res 2018; 136:13-32. [PMID: 29395358 DOI: 10.1016/j.neures.2018.01.003] [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: 12/16/2017] [Revised: 01/11/2018] [Accepted: 01/11/2018] [Indexed: 11/28/2022]
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) and calmodulin (CaM) play essential roles in synaptic plasticity, which is an elementary process of learning and memory. In this study, fluorescence correlation spectroscopy (FCS) revealed diffusion properties of CaM, CaMKIIα and CaMKIIβ proteins in human embryonic kidney 293 (HEK293) cells and hippocampal neurons. A simultaneous multiple-point FCS recording system was developed on a random-access two-photon microscope, which facilitated efficient analysis of molecular dynamics in neuronal compartments. The diffusion of CaM in neurons was slower than that in HEK293 cells at rest, while the diffusion in stimulated neurons was accelerated and indistinguishable from that in HEK293 cells. This implied that activity-dependent binding partners of CaM exist in neurons, which slow down the diffusion at rest. Diffusion properties of CaMKIIα and β proteins implied that major populations of these proteins exist as holoenzymatic forms. Upon stimulation of neurons, the diffusion of CaMKIIα and β proteins became faster with reduced particle brightness, indicating drastic structural changes of the proteins such as dismissal from holoenzyme structure and further fragmentation.
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Affiliation(s)
- Morteza Heidarinejad
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
| | - Hideki Nakamura
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
| | - Takafumi Inoue
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
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25
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Meng Y, Lin W, Li C, Chen SC. Fast two-snapshot structured illumination for temporal focusing microscopy with enhanced axial resolution. OPTICS EXPRESS 2017; 25:23109-23121. [PMID: 29041614 DOI: 10.1364/oe.25.023109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
We present a new two-snapshot structured light illumination (SLI) reconstruction algorithm for fast image acquisition. The new algorithm, which only requires two mutually π phase-shifted raw structured images, is implemented on a custom-built temporal focusing fluorescence microscope (TFFM) to enhance its axial resolution via a digital micromirror device (DMD). First, the orientation of the modulated sinusoidal fringe patterns is automatically identified via spatial frequency vector detection. Subsequently, the modulated in-focal-plane images are obtained via rotation and subtraction. Lastly, a parallel amplitude demodulation method, derived based on Hilbert transform, is applied to complete the decoding processes. To demonstrate the new SLI algorithm, a TFFM is custom-constructed, where a DMD replaces the generic blazed grating in the system and simultaneously functions as a diffraction grating and a programmable binary mask, generating arbitrary fringe patterns. The experimental results show promising depth-discrimination capability with an axial resolution enhancement factor of 1.25, which matches well with the theoretical estimation, i.e, 1.27. Imaging experiments on pollen grain and mouse kidney samples have been performed. The results indicate that the two-snapshot algorithm presents comparable contrast reconstruction and optical cross-sectioning capability than those adopting the conventional root-mean-square (RMS) reconstruction method. The two-snapshot method can be readily applied to any sinusoidally modulated illumination systems to realize high-speed 3D imaging as less frames are required for each in-focal-plane image restoration, i.e., the image acquisition speed is improved by 2.5 times for any two-photon systems.
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26
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Chamberland S, Yang HH, Pan MM, Evans SW, Guan S, Chavarha M, Yang Y, Salesse C, Wu H, Wu JC, Clandinin TR, Toth K, Lin MZ, St-Pierre F. Fast two-photon imaging of subcellular voltage dynamics in neuronal tissue with genetically encoded indicators. eLife 2017; 6. [PMID: 28749338 PMCID: PMC5584994 DOI: 10.7554/elife.25690] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 07/21/2017] [Indexed: 12/22/2022] Open
Abstract
Monitoring voltage dynamics in defined neurons deep in the brain is critical for unraveling the function of neuronal circuits but is challenging due to the limited performance of existing tools. In particular, while genetically encoded voltage indicators have shown promise for optical detection of voltage transients, many indicators exhibit low sensitivity when imaged under two-photon illumination. Previous studies thus fell short of visualizing voltage dynamics in individual neurons in single trials. Here, we report ASAP2s, a novel voltage indicator with improved sensitivity. By imaging ASAP2s using random-access multi-photon microscopy, we demonstrate robust single-trial detection of action potentials in organotypic slice cultures. We also show that ASAP2s enables two-photon imaging of graded potentials in organotypic slice cultures and in Drosophila. These results demonstrate that the combination of ASAP2s and fast two-photon imaging methods enables detection of neural electrical activity with subcellular spatial resolution and millisecond-timescale precision. DOI:http://dx.doi.org/10.7554/eLife.25690.001
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Affiliation(s)
- Simon Chamberland
- Department of Psychiatry and Neuroscience, Quebec Mental Health Institute, Université Laval, Québec, Canada
| | - Helen H Yang
- Department of Neurobiology, Stanford University, Stanford, United States
| | - Michael M Pan
- Department of Bioengineering, Stanford University, Stanford, United States.,Department of Pediatrics, Stanford University, Stanford, United States
| | - Stephen W Evans
- Department of Neurobiology, Stanford University, Stanford, United States.,Department of Bioengineering, Stanford University, Stanford, United States.,Department of Pediatrics, Stanford University, Stanford, United States
| | - Sihui Guan
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Mariya Chavarha
- Department of Neurobiology, Stanford University, Stanford, United States.,Department of Bioengineering, Stanford University, Stanford, United States.,Department of Pediatrics, Stanford University, Stanford, United States
| | - Ying Yang
- Department of Neurobiology, Stanford University, Stanford, United States.,Department of Bioengineering, Stanford University, Stanford, United States.,Department of Pediatrics, Stanford University, Stanford, United States
| | - Charleen Salesse
- Department of Psychiatry and Neuroscience, Quebec Mental Health Institute, Université Laval, Québec, Canada
| | - Haodi Wu
- Stanford Cardiovascular Institute, Stanford University, Stanford, United States
| | - Joseph C Wu
- Stanford Cardiovascular Institute, Stanford University, Stanford, United States
| | - Thomas R Clandinin
- Department of Neurobiology, Stanford University, Stanford, United States
| | - Katalin Toth
- Department of Psychiatry and Neuroscience, Quebec Mental Health Institute, Université Laval, Québec, Canada
| | - Michael Z Lin
- Department of Neurobiology, Stanford University, Stanford, United States.,Department of Bioengineering, Stanford University, Stanford, United States.,Department of Pediatrics, Stanford University, Stanford, United States
| | - François St-Pierre
- Department of Bioengineering, Stanford University, Stanford, United States.,Department of Pediatrics, Stanford University, Stanford, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States
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27
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Task Learning Promotes Plasticity of Interneuron Connectivity Maps in the Olfactory Bulb. J Neurosci 2017; 36:8856-71. [PMID: 27559168 DOI: 10.1523/jneurosci.0794-16.2016] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 07/08/2016] [Indexed: 01/06/2023] Open
Abstract
UNLABELLED Elucidating patterns of functional synaptic connectivity and deciphering mechanisms of how plasticity influences such connectivity is essential toward understanding brain function. In the mouse olfactory bulb (OB), principal neurons (mitral/tufted cells) make reciprocal connections with local inhibitory interneurons, including granule cells (GCs) and external plexiform layer (EPL) interneurons. Our current understanding of the functional connectivity between these cell types, as well as their experience-dependent plasticity, remains incomplete. By combining acousto-optic deflector-based scanning microscopy and genetically targeted expression of Channelrhodopsin-2, we mapped connections in a cell-type-specific manner between mitral cells (MCs) and GCs or between MCs and EPL interneurons. We found that EPL interneurons form broad patterns of connectivity with MCs, whereas GCs make more restricted connections with MCs. Using an olfactory associative learning paradigm, we found that these circuits displayed differential features of experience-dependent plasticity. Whereas reciprocal connectivity between MCs and EPL interneurons was nonplastic, the connections between GCs and MCs were dynamic and adaptive. Interestingly, experience-dependent plasticity of GCs occurred only in certain stages of neuronal maturation. We show that different interneuron subtypes form distinct connectivity maps and modes of experience-dependent plasticity in the OB, which may reflect their unique functional roles in information processing. SIGNIFICANCE STATEMENT Deducing how specific interneuron subtypes contribute to normal circuit function requires understanding the dynamics of their connections. In the olfactory bulb (OB), diverse interneuron subtypes vastly outnumber principal excitatory cells. By combining acousto-optic deflector-based scanning microscopy, electrophysiology, and genetically targeted expression of Channelrhodopsin-2, we mapped the functional connectivity between mitral cells (MCs) and OB interneurons in a cell-type-specific manner. We found that, whereas external plexiform layer (EPL) interneurons show broadly distributed patterns of stable connectivity with MCs, adult-born granule cells show dynamic and plastic patterns of synaptic connectivity with task learning. Together, these findings reveal the diverse roles for interneuons within sensory circuits toward information learning and processing.
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28
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Ji N, Freeman J, Smith SL. Technologies for imaging neural activity in large volumes. Nat Neurosci 2017; 19:1154-64. [PMID: 27571194 DOI: 10.1038/nn.4358] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 07/14/2016] [Indexed: 02/08/2023]
Abstract
Neural circuitry has evolved to form distributed networks that act dynamically across large volumes. Conventional microscopy collects data from individual planes and cannot sample circuitry across large volumes at the temporal resolution relevant to neural circuit function and behaviors. Here we review emerging technologies for rapid volume imaging of neural circuitry. We focus on two critical challenges: the inertia of optical systems, which limits image speed, and aberrations, which restrict the image volume. Optical sampling time must be long enough to ensure high-fidelity measurements, but optimized sampling strategies and point-spread function engineering can facilitate rapid volume imaging of neural activity within this constraint. We also discuss new computational strategies for processing and analyzing volume imaging data of increasing size and complexity. Together, optical and computational advances are providing a broader view of neural circuit dynamics and helping elucidate how brain regions work in concert to support behavior.
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Affiliation(s)
- Na Ji
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, USA
| | - Jeremy Freeman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, USA
| | - Spencer L Smith
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.,Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.,Carolina Institute for Developmental Disabilities, University of North Carolina School of Medicine, Chapel Hill, North Carolina
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29
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Wang T, Zhang C, Aleksov A, Salama I, Kar A. Two-dimensional refractive index modulation by phased array transducers in acousto-optic deflectors. APPLIED OPTICS 2017; 56:688-694. [PMID: 28157931 DOI: 10.1364/ao.56.000688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Acousto-optic deflectors are photonic devices that are used for scanning high-power laser beams in advanced microprocessing applications such as marking and direct writing. The operation of conventional deflectors mostly relies on one-dimensional sinusoidal variation of the refractive index in an acousto-optic medium. Sometimes static phased array transducers, such as step configuration or planar configuration transducer architecture, are used to tilt the index modulation planes for achieving higher performance and higher resolution than a single transducer AO device. However, the index can be modulated in two dimensions, and the modulation plane can be tilted arbitrarily by creating dynamic phase gratings in the medium using phased array transducers. This type of dynamic two-dimensional acousto-optic deflector can provide better performance using, for example, a large deflection angle and high diffraction efficiency. This paper utilizes an ultrasonic beam steering approach to study the two-dimensional strain-induced index modulation due to the photoelastic effect. The modulation is numerically simulated, and the effects of various parameters, such as the operating radiofrequency of the transducers, the ultrasonic beam steering angle, and different combinations of pressure on each element of the transducer array, are demonstrated.
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30
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Consistent estimation of complete neuronal connectivity in large neuronal populations using sparse "shotgun" neuronal activity sampling. J Comput Neurosci 2016; 41:157-84. [PMID: 27515518 DOI: 10.1007/s10827-016-0611-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 06/09/2016] [Accepted: 06/13/2016] [Indexed: 11/27/2022]
Abstract
We investigate the properties of recently proposed "shotgun" sampling approach for the common inputs problem in the functional estimation of neuronal connectivity. We study the asymptotic correctness, the speed of convergence, and the data size requirements of such an approach. We show that the shotgun approach can be expected to allow the inference of complete connectivity matrix in large neuronal populations under some rather general conditions. However, we find that the posterior error of the shotgun connectivity estimator grows quickly with the size of unobserved neuronal populations, the square of average connectivity strength, and the square of observation sparseness. This implies that the shotgun connectivity estimation will require significantly larger amounts of neuronal activity data whenever the number of neurons in observed neuronal populations remains small. We present a numerical approach for solving the shotgun estimation problem in general settings and use it to demonstrate the shotgun connectivity inference in the examples of simulated synfire and weakly coupled cortical neuronal networks.
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31
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Chien FC, Lien CH, Dai YH. Dual-color dynamic tracking of GM-CSF receptors/JAK2 kinases signaling activation using temporal focusing multiphoton fluorescence excitation and astigmatic imaging. OPTICS EXPRESS 2015; 23:30943-30955. [PMID: 26698726 DOI: 10.1364/oe.23.030943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The dual-color dynamic particle tracking approach that uses temporal focusing multiphoton fluorescence excitation and two-channel astigmatic imaging is utilized to track molecular trajectories in three dimensions to explore molecular interactions. Images of two fluorophores were obtained to extract their positions by optical sectioning excitation using a fast temporal focusing multiphoton excitation microscope (TFMPEM) and by the simultaneous collection of data in two channels. The presented pair of cylindrical lenses, which was used to adjust the astigmatism effect with the minimum shifting of the imaging plane, was more feasible and flexible than single cylindrical lens for aligning two separate detection channels in astigmatic imaging. The lateral and axial positioning resolutions were observed to be approximately 9-13 nm and 23-30 nm respectively, for the two fluorescence channels. The dynamic movement and binding behavior of clusters of GM-CSF receptors and JAK2 kinases in HeLa cells in the presence of GM-CSF ligands were observed. Therefore, the proposed dual-color tracking strategy is useful for the dynamic study of molecular interactions in living specimens with a fast frame rate, less photobleaching, better penetration depth, and minimum optical trapping force.
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32
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Reddy GD, Cotton RJ, Tolias AS, Saggau P. Random-Access Multiphoton Microscopy for Fast Three-Dimensional Imaging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:455-72. [PMID: 26238064 DOI: 10.1007/978-3-319-17641-3_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Studies in several important areas of neuroscience, including analysis of single neurons as well as neural networks, continue to be limited by currently available experimental tools. By combining molecular probes of cellular function, such as voltage-sensitive or calcium-sensitive dyes, with advanced microscopy techniques such as multiphoton microscopy, experimental neurophysiologists have been able to partially reduce this limitation. These approaches usually provide the needed spatial resolution along with convenient optical sectioning capabilities for isolating regions of interest. However, they often fall short in providing the necessary temporal resolution, primarily due to their restrained laser scanning mechanisms. In this regard, we review a method of laser scanning for multiphoton microscopy that overcomes the temporal limitations of pervious approaches and allows for what is known as 3D Random Access Multiphoton (3D RAMP) microscopy, an imaging technique that supports full three dimensional recording of many sites of interest on physiologically relevant time scales.
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33
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Young MD, Field JJ, Sheetz KE, Bartels RA, Squier J. A pragmatic guide to multiphoton microscope design. ADVANCES IN OPTICS AND PHOTONICS 2015; 7:276-378. [PMID: 27182429 PMCID: PMC4863715 DOI: 10.1364/aop.7.000276] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Multiphoton microscopy has emerged as a ubiquitous tool for studying microscopic structure and function across a broad range of disciplines. As such, the intent of this paper is to present a comprehensive resource for the construction and performance evaluation of a multiphoton microscope that will be understandable to the broad range of scientific fields that presently exploit, or wish to begin exploiting, this powerful technology. With this in mind, we have developed a guide to aid in the design of a multiphoton microscope. We discuss source selection, optical management of dispersion, image-relay systems with scan optics, objective-lens selection, single-element light-collection theory, photon-counting detection, image rendering, and finally, an illustrated guide for building an example microscope.
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Affiliation(s)
- Michael D. Young
- Center for Microintegrated Optics for Advanced Biological Control, Department of Physics, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, USA
| | - Jeffrey J. Field
- W. M. Keck Laboratory for Raman Imaging of Cell-to-Cell Communications, Colorado State University, Fort Collins, Colorado 80523, USA
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Kraig E. Sheetz
- Photonics Research Center, Department of Physics and Nuclear Engineering, United States Military Academy, West Point, New York 10996, USA
| | - Randy A. Bartels
- W. M. Keck Laboratory for Raman Imaging of Cell-to-Cell Communications, Colorado State University, Fort Collins, Colorado 80523, USA
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Jeff Squier
- Center for Microintegrated Optics for Advanced Biological Control, Department of Physics, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, USA
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34
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Abstract
Advances in optical manipulation and observation of neural activity have set the stage for widespread implementation of closed-loop and activity-guided optical control of neural circuit dynamics. Closing the loop optogenetically (i.e., basing optogenetic stimulation on simultaneously observed dynamics in a principled way) is a powerful strategy for causal investigation of neural circuitry. In particular, observing and feeding back the effects of circuit interventions on physiologically relevant timescales is valuable for directly testing whether inferred models of dynamics, connectivity, and causation are accurate in vivo. Here we highlight technical and theoretical foundations as well as recent advances and opportunities in this area, and we review in detail the known caveats and limitations of optogenetic experimentation in the context of addressing these challenges with closed-loop optogenetic control in behaving animals.
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Affiliation(s)
- Logan Grosenick
- Department of Bioengineering, Stanford University, Stanford, CA 94305 USA; CNC Program, Stanford University, Stanford, CA 94305 USA; Neurosciences Program, Stanford University, Stanford, CA 94305 USA
| | - James H Marshel
- Department of Bioengineering, Stanford University, Stanford, CA 94305 USA; CNC Program, Stanford University, Stanford, CA 94305 USA
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA 94305 USA; CNC Program, Stanford University, Stanford, CA 94305 USA; Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305 USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305 USA.
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35
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Fisher JAN, Salzberg BM. Two-Photon Excitation of Fluorescent Voltage-Sensitive Dyes: Monitoring Membrane Potential in the Infrared. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:427-53. [PMID: 26238063 DOI: 10.1007/978-3-319-17641-3_17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Functional imaging microscopy based on voltage-sensitive dyes (VSDs) has proven effective for revealing spatio-temporal patterns of activity in vivo and in vitro. Microscopy based on two-photon excitation of fluorescent VSDs offers the possibility of recording sub-millisecond membrane potential changes on micron length scales in cells that lie upwards of one millimeter below the brain's surface. Here we describe progress in monitoring membrane voltage using two-photon excitation (TPE) of VSD fluorescence, and detail an application of this emerging technology in which action potentials were recorded in single trials from individual mammalian nerve terminals in situ. Prospects for, and limitations of this method are reviewed.
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36
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Macias-Romero C, Didier MEP, Jourdain P, Marquet P, Magistretti P, Tarun OB, Zubkovs V, Radenovic A, Roke S. High throughput second harmonic imaging for label-free biological applications. OPTICS EXPRESS 2014; 22:31102-31112. [PMID: 25607059 DOI: 10.1364/oe.22.031102] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Second harmonic generation (SHG) is inherently sensitive to the absence of spatial centrosymmetry, which can render it intrinsically sensitive to interfacial processes, chemical changes and electrochemical responses. Here, we seek to improve the imaging throughput of SHG microscopy by using a wide-field imaging scheme in combination with a medium-range repetition rate amplified near infrared femtosecond laser source and gated detection. The imaging throughput of this configuration is tested by measuring the optical image contrast for different image acquisition times of BaTiO₃ nanoparticles in two different wide-field setups and one commercial point-scanning configuration. We find that the second harmonic imaging throughput is improved by 2-3 orders of magnitude compared to point-scan imaging. Capitalizing on this result, we perform low fluence imaging of (parts of) living mammalian neurons in culture.
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37
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So PTC, Yew EYS, Rowlands C. High-throughput nonlinear optical microscopy. Biophys J 2014; 105:2641-54. [PMID: 24359736 DOI: 10.1016/j.bpj.2013.08.051] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 08/19/2013] [Accepted: 08/22/2013] [Indexed: 01/06/2023] Open
Abstract
High-resolution microscopy methods based on different nonlinear optical (NLO) contrast mechanisms are finding numerous applications in biology and medicine. While the basic implementations of these microscopy methods are relatively mature, an important direction of continuing technological innovation lies in improving the throughput of these systems. Throughput improvement is expected to be important for studying fast kinetic processes, for enabling clinical diagnosis and treatment, and for extending the field of image informatics. This review will provide an overview of the fundamental limitations on NLO microscopy throughput. We will further cover several important classes of high-throughput NLO microscope designs with discussions on their strengths and weaknesses and their key biomedical applications. Finally, this review will close with a perspective of potential future technological improvements in this field.
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Affiliation(s)
- Peter T C So
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; Laser Biomedical Research Center, Massachusetts Institute of Technology, Cambridge, Massachusetts; BioSyM Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore, Singapore.
| | - Elijah Y S Yew
- BioSyM Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore, Singapore
| | - Christopher Rowlands
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; Laser Biomedical Research Center, Massachusetts Institute of Technology, Cambridge, Massachusetts
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38
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Grewe BF, Helmchen F. High-speed two-photon calcium imaging of neuronal population activity using acousto-optic deflectors. Cold Spring Harb Protoc 2014; 2014:618-29. [PMID: 24890212 DOI: 10.1101/pdb.prot081778] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Two-photon calcium imaging of neuronal populations allows optical measurements of spiking activity in living animals. However, laser-scanning microscopes with galvanometric scan mirrors are too slow to capture population activity on a millisecond timescale. This protocol describes a two-photon microscope that is based on two-dimensional laser scanning with acousto-optic deflectors (AODs), enabling high-speed in vivo recording of neuronal population activity at temporal resolutions of several hundred hertz. The detailed construction plan of the AOD-based microscope is accompanied by equally detailed optimization procedures. We also introduce a novel random-access pattern scanning (RAPS) technique for high-speed in vivo measurements of neuronal population activity. AOD-based RAPS can measure calcium transients in neocortical neuronal populations, revealing spike trains with near-millisecond precision. The current limitations of the AOD-based microscope are discussed, and we provide an outlook of its future applications.
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39
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Raol J, Cox SJ. Inverse problems in neuronal calcium signaling. J Math Biol 2014; 67:3-23. [PMID: 22290315 DOI: 10.1007/s00285-012-0507-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 01/14/2012] [Indexed: 10/14/2022]
Abstract
Calcium is the most important of the brain's second messengers. Thanks to engineered fluorescent indicators and caged compounds we have an excellent qualitative picture of its regulation and impact.With the advent of new scanning technology that permits one to observe the calcium signal throughout a highly branched neuron the potential exists for functional, single cell, quantitative calcium imaging. To help realize that potential we analyze a sequence of four inverse problems that infer the parameters of the cytosolic calcium buffers and plasma membrane calcium pumps and channels from the light shed by fluorescent indicators following specific stimulus protocols. Our analyses lead in each case to practical algorithms that we illustrate and test on synthetic data.
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Affiliation(s)
- Jay Raol
- Department of Computational and Applied Mathematics, Rice University, Houston, TX, USA
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40
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Ferrantini C, Crocini C, Coppini R, Vanzi F, Tesi C, Cerbai E, Poggesi C, Pavone FS, Sacconi L. The transverse-axial tubular system of cardiomyocytes. Cell Mol Life Sci 2013; 70:4695-710. [PMID: 23846763 PMCID: PMC11113601 DOI: 10.1007/s00018-013-1410-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 06/03/2013] [Accepted: 06/13/2013] [Indexed: 10/26/2022]
Abstract
A characteristic histological feature of striated muscle cells is the presence of deep invaginations of the plasma membrane (sarcolemma), most commonly referred to as T-tubules or the transverse-axial tubular system (TATS). TATS mediates the rapid spread of the electrical signal (action potential) to the cell core triggering Ca(2+) release from the sarcoplasmic reticulum, ultimately inducing myofilament contraction (excitation-contraction coupling). T-tubules, first described in vertebrate skeletal muscle cells, have also been recognized for a long time in mammalian cardiac ventricular myocytes, with a structure and a function that in recent years have been shown to be far more complex and pivotal for cardiac function than initially thought. Renewed interest in T-tubule function stems from the loss and disorganization of T-tubules found in a number of pathological conditions including human heart failure (HF) and dilated and hypertrophic cardiomyopathies, as well as in animal models of HF, chronic ischemia and atrial fibrillation. Disease-related remodeling of the TATS leads to asynchronous and inhomogeneous Ca(2+)-release, due to the presence of orphan ryanodine receptors that have lost their coupling with the dihydropyridine receptors and are either not activated or activated with a delay. Here, we review the physiology of the TATS, focusing first on the relationship between function and structure, and then describing T-tubular remodeling and its reversal in disease settings and following effective therapeutic approaches.
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Affiliation(s)
- C. Ferrantini
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - C. Crocini
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
| | - R. Coppini
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - F. Vanzi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Biology, University of Florence, Florence, Italy
| | - C. Tesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - E. Cerbai
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - C. Poggesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - F. S. Pavone
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
| | - L. Sacconi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
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41
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Fast state-space methods for inferring dendritic synaptic connectivity. J Comput Neurosci 2013; 36:415-43. [DOI: 10.1007/s10827-013-0478-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 07/22/2013] [Accepted: 08/14/2013] [Indexed: 02/06/2023]
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42
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Bechtold P, Hohenstein R, Schmidt M. Evaluation of disparate laser beam deflection technologies by means of number and rate of resolvable spots. OPTICS LETTERS 2013; 38:2934-2937. [PMID: 24104614 DOI: 10.1364/ol.38.002934] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We introduce a method to objectively evaluate systems of differing beam deflection technologies that commonly are described by disparate technical specifications. Using our new approach based on resolvable spots we will compare commercially available random-access beam deflection technologies, namely galvanometer scanners, piezo scanners, MEMS scanners, acousto-optic deflectors, and electro-optic deflectors.
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43
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Bechtold P, Hohenstein R, Schmidt M. Beam shaping and high-speed, cylinder-lens-free beam guiding using acousto-optical deflectors without additional compensation optics. OPTICS EXPRESS 2013; 21:14627-14635. [PMID: 23787650 DOI: 10.1364/oe.21.014627] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Using acousto-optical deflectors at high deflection speeds via acoustical frequency chirping induces astigmatism, deforming the laser beam in an unfavorable way. Within the paper, we present a method to prevent this effect for an ultrashort pulsed laser beam via acoustical frequency jumps synchronized to the pulse-to-pulse pause. We also demonstrate and give a method to calculate beam shaping capability of acousto-optical deflectors via arbitrary spatial frequency developments during ultrashort laser pulse transit through the deflector. Cylinder-lens-free deflection at >2000 rad/s and beam shaping capability is demonstrated experimentally. In our experiments the switching time between two beam shapes is 1 µs.
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Affiliation(s)
- Peter Bechtold
- Institute of Photonic Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Str. 3, 91052 Erlangen, Germany.
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44
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Abstract
Recent advances in automated high-resolution fluorescence microscopy and robotic handling have made the systematic and cost effective study of diverse morphological changes within a large population of cells possible under a variety of perturbations, e.g., drugs, compounds, metal catalysts, RNA interference (RNAi). Cell population-based studies deviate from conventional microscopy studies on a few cells, and could provide stronger statistical power for drawing experimental observations and conclusions. However, it is challenging to manually extract and quantify phenotypic changes from the large amounts of complex image data generated. Thus, bioimage informatics approaches are needed to rapidly and objectively quantify and analyze the image data. This paper provides an overview of the bioimage informatics challenges and approaches in image-based studies for drug and target discovery. The concepts and capabilities of image-based screening are first illustrated by a few practical examples investigating different kinds of phenotypic changes caEditorsused by drugs, compounds, or RNAi. The bioimage analysis approaches, including object detection, segmentation, and tracking, are then described. Subsequently, the quantitative features, phenotype identification, and multidimensional profile analysis for profiling the effects of drugs and targets are summarized. Moreover, a number of publicly available software packages for bioimage informatics are listed for further reference. It is expected that this review will help readers, including those without bioimage informatics expertise, understand the capabilities, approaches, and tools of bioimage informatics and apply them to advance their own studies.
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Affiliation(s)
- Fuhai Li
- NCI Center for Modeling Cancer Development, Department of Systems Medicine and Bioengineering, The Methodist Hospital Research Institute, Weil Medical College of Cornell University, Houston, Texas, United States of America
| | - Zheng Yin
- NCI Center for Modeling Cancer Development, Department of Systems Medicine and Bioengineering, The Methodist Hospital Research Institute, Weil Medical College of Cornell University, Houston, Texas, United States of America
| | - Guangxu Jin
- NCI Center for Modeling Cancer Development, Department of Systems Medicine and Bioengineering, The Methodist Hospital Research Institute, Weil Medical College of Cornell University, Houston, Texas, United States of America
| | - Hong Zhao
- NCI Center for Modeling Cancer Development, Department of Systems Medicine and Bioengineering, The Methodist Hospital Research Institute, Weil Medical College of Cornell University, Houston, Texas, United States of America
| | - Stephen T. C. Wong
- NCI Center for Modeling Cancer Development, Department of Systems Medicine and Bioengineering, The Methodist Hospital Research Institute, Weil Medical College of Cornell University, Houston, Texas, United States of America
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van den Broek B, Ashcroft B, Oosterkamp TH, van Noort J. Parallel nanometric 3D tracking of intracellular gold nanorods using multifocal two-photon microscopy. NANO LETTERS 2013; 13:980-6. [PMID: 23360249 DOI: 10.1021/nl3040509] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We report a novel technique for long-term parallel three dimensional (3D)-tracking of gold nanorods in live cells with nanometer resolution. Gold nanorods feature a strong plasmon-enhanced two-photon luminescence, can be easily functionalized, and have been shown to be nontoxic. These properties make gold nanorods very suitable for in vivo two-photon luminescence microscopy. By rapid multifocal scanning, we combine the advantages of 3D molecular tracking methods using wide-field imaging with the advantages of two-photon microscopy. Isolated gold nanorods can be localized with a resolution of 4 nm in the xy-plane and 8 nm in the z-direction. The polarization-dependence of the two-photon luminescence signal can be used to resolve the angular orientation, even when two gold nanorods are separated by less than the diffraction limit. Individual nanorods in live U2OS cells could be followed in 3 dimensions for over 30 min, with a photon noise limited accuracy, and a time resolution of 50 ms in 2D and 500 ms in 3D.
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Affiliation(s)
- Bram van den Broek
- Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
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46
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Kastelik JC, Dupont S, Yushkov KB, Gazalet J. Frequency and angular bandwidth of acousto-optic deflectors with ultrasonic walk-off. ULTRASONICS 2013; 53:219-224. [PMID: 22749524 DOI: 10.1016/j.ultras.2012.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 05/31/2012] [Accepted: 06/01/2012] [Indexed: 06/01/2023]
Abstract
In the paper, bandwidth parameters of acousto-optical deflectors (AODs) are analyzed from the point of view of acoustical anisotropy. Equations for bandwidth and central frequency of AOD are derived for arbitrary propagation direction of ultrasound in optically uniaxial crystals. The phenomenon of bandwidth shift due to phase mismatch at the central frequency is studied theoretically and verified experimentally.
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47
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Abstract
The small size of neuronal dendrites and spines combined with the high speed of neurophysiological signals, such as transients in membrane potential or ion concentration, necessitates that any functional study of these structures uses recording methods with both high spatial and high temporal resolutions. In this regard, conventional two-photon microscopy, in combination with fluorescent indicators sensitive to physiological parameters, has proved to be only a partial solution by providing near-diffraction-limited spatial resolution even when imaging structures deep inside light-scattering tissue. This is because the relatively slow beam-scanning methods used in most conventional two-photon microscopes severely limit the extent to which functional data can be recorded. Here, we detail developments to create high-speed two-photon imaging systems that overcome this limitation and discuss important considerations that must be taken into account when attempting to construct such systems.
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48
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Abstract
Intracellular calcium dynamics is critical for many functions of cerebellar granule cells (GrCs) including membrane excitability, synaptic plasticity, apoptosis, and regulation of gene transcription. Recent measurements of calcium responses in GrCs to depolarization and synaptic stimulation reveal spatial compartmentalization and heterogeneity within dendrites of these cells. However, the main determinants of local calcium dynamics in GrCs are still poorly understood. One reason is that there have been few published studies of calcium dynamics in intact GrCs in their native environment. In the absence of complete information, biophysically realistic models are useful for testing whether specific Ca(2+) handling mechanisms may account for existing experimental observations. Simulation results can be used to identify critical measurements that would discriminate between different models. In this review, we briefly describe experimental studies and phenomenological models of Ca(2+) signaling in GrC, and then discuss a particular biophysical model, with a special emphasis on an approach for obtaining information regarding the distribution of Ca(2+) handling systems under conditions of incomplete experimental data. Use of this approach suggests that Ca(2+) channels and fixed endogenous Ca(2+) buffers are highly heterogeneously distributed in GrCs. Research avenues for investigating calcium dynamics in GrCs by a combination of experimental and modeling studies are proposed.
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Affiliation(s)
- Elena È Saftenku
- Department of General Physiology of Nervous System, A. A. Bogomoletz Institute of Physiology, 4 Bogomoletz St., Kyiv 01024, Ukraine.
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Ranganathan GN, Koester HJ. Optical recording of suprathreshold neural activity with single-cell and single-spike resolution. J Vis Exp 2012:e4052. [PMID: 22972033 DOI: 10.3791/4052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Signaling of information in the vertebrate central nervous system is often carried by populations of neurons rather than individual neurons. Also propagation of suprathreshold spiking activity involves populations of neurons. Empirical studies addressing cortical function directly thus require recordings from populations of neurons with high resolution. Here we describe an optical method and a deconvolution algorithm to record neural activity from up to 100 neurons with single-cell and single-spike resolution. This method relies on detection of the transient increases in intracellular somatic calcium concentration associated with suprathreshold electrical spikes (action potentials) in cortical neurons. High temporal resolution of the optical recordings is achieved by a fast random-access scanning technique using acousto-optical deflectors (AODs). Two-photon excitation of the calcium-sensitive dye results in high spatial resolution in opaque brain tissue. Reconstruction of spikes from the fluorescence calcium recordings is achieved by a maximum-likelihood method. Simultaneous electrophysiological and optical recordings indicate that our method reliably detects spikes (>97% spike detection efficiency), has a low rate of false positive spike detection (< 0.003 spikes/sec), and a high temporal precision (about 3 msec). This optical method of spike detection can be used to record neural activity in vitro and in anesthetized animals in vivo.
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50
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Endogenous fluorescence signatures in living pluripotent stem cells change with loss of potency. PLoS One 2012; 7:e43708. [PMID: 22952742 PMCID: PMC3430704 DOI: 10.1371/journal.pone.0043708] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 07/25/2012] [Indexed: 12/22/2022] Open
Abstract
The therapeutic potential of stem cells is limited by the non-uniformity of their phenotypic state. Thus it would be advantageous to noninvasively monitor stem cell status. Driven by this challenge, we employed multidimensional multiphoton microscopy to quantify changes in endogenous fluorescence occurring with pluripotent stem cell differentiation. We found that global and cellular-scale fluorescence lifetime of human embryonic stem cells (hESC) and murine embryonic stem cells (mESC) consistently decreased with differentiation. Less consistent were trends in endogenous fluorescence intensity with differentiation, suggesting intensity is more readily impacted by nuances of species and scale of analysis. What emerges is a practical and accessible approach to evaluate, and ultimately enrich, living stem cell populations based on changes in metabolism that could be exploited for both research and clinical applications.
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