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Telliez C, De Sars V, Emiliani V, Ronzitti E. Descanned fast light targeting (deFLiT) two-photon optogenetics. Biomed Opt 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Bollmann Y, Modol L, Tressard T, Vorobyev A, Dard R, Brustlein S, Sims R, Bendifallah I, Leprince E, de Sars V, Ronzitti E, Baude A, Adesnik H, Picardo MA, Platel JC, Emiliani V, Angulo-Garcia D, Cossart R. Prominent in vivo influence of single interneurons in the developing barrel cortex. Nat Neurosci 2023; 26:1555-1565. [PMID: 37653166 DOI: 10.1038/s41593-023-01405-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 07/13/2023] [Indexed: 09/02/2023]
Abstract
Spontaneous synchronous activity is a hallmark of developing brain circuits and promotes their formation. Ex vivo, synchronous activity was shown to be orchestrated by a sparse population of highly connected GABAergic 'hub' neurons. The recent development of all-optical methods to record and manipulate neuronal activity in vivo now offers the unprecedented opportunity to probe the existence and function of hub cells in vivo. Using calcium imaging, connectivity analysis and holographic optical stimulation, we show that single GABAergic, but not glutamatergic, neurons influence population dynamics in the barrel cortex of non-anaesthetized mouse pups. Single GABAergic cells mainly exert an inhibitory influence on both spontaneous and sensory-evoked population bursts. Their network influence scales with their functional connectivity, with highly connected hub neurons displaying the strongest impact. We propose that hub neurons function in tailoring intrinsic cortical dynamics to external sensory inputs.
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Affiliation(s)
- Yannick Bollmann
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Laura Modol
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Thomas Tressard
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Artem Vorobyev
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Robin Dard
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Sophie Brustlein
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Ruth Sims
- Wavefront-Engineering Microscopy Group, Photonics Department, Vision Institute, Sorbonne University, INSERM, CNRS, Paris, France
| | - Imane Bendifallah
- Wavefront-Engineering Microscopy Group, Photonics Department, Vision Institute, Sorbonne University, INSERM, CNRS, Paris, France
| | - Erwan Leprince
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Vincent de Sars
- Wavefront-Engineering Microscopy Group, Photonics Department, Vision Institute, Sorbonne University, INSERM, CNRS, Paris, France
| | - Emiliano Ronzitti
- Wavefront-Engineering Microscopy Group, Photonics Department, Vision Institute, Sorbonne University, INSERM, CNRS, Paris, France
| | - Agnès Baude
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Hillel Adesnik
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Michel Aimé Picardo
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Jean-Claude Platel
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France
| | - Valentina Emiliani
- Wavefront-Engineering Microscopy Group, Photonics Department, Vision Institute, Sorbonne University, INSERM, CNRS, Paris, France
| | - David Angulo-Garcia
- Departamento de Matemáticas y Estadística, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales, Colombia
| | - Rosa Cossart
- Aix Marseille Univ, Inserm, INMED, Turing Center for Living Systems, Marseille, France.
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3
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Faini G, Tanese D, Molinier C, Telliez C, Hamdani M, Blot F, Tourain C, de Sars V, Del Bene F, Forget BC, Ronzitti E, Emiliani V. Ultrafast light targeting for high-throughput precise control of neuronal networks. Nat Commun 2023; 14:1888. [PMID: 37019891 PMCID: PMC10074378 DOI: 10.1038/s41467-023-37416-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/16/2023] [Indexed: 04/07/2023] Open
Abstract
Two-photon, single-cell resolution optogenetics based on holographic light-targeting approaches enables the generation of precise spatiotemporal neuronal activity patterns and thus a broad range of experimental applications, such as high throughput connectivity mapping and probing neural codes for perception. Yet, current holographic approaches limit the resolution for tuning the relative spiking time of distinct cells to a few milliseconds, and the achievable number of targets to 100-200, depending on the working depth. To overcome these limitations and expand the capabilities of single-cell optogenetics, we introduce an ultra-fast sequential light targeting (FLiT) optical configuration based on the rapid switching of a temporally focused beam between holograms at kHz rates. We used FLiT to demonstrate two illumination protocols, termed hybrid- and cyclic-illumination, and achieve sub-millisecond control of sequential neuronal activation and high throughput multicell illumination in vitro (mouse organotypic and acute brain slices) and in vivo (zebrafish larvae and mice), while minimizing light-induced thermal rise. These approaches will be important for experiments that require rapid and precise cell stimulation with defined spatio-temporal activity patterns and optical control of large neuronal ensembles.
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Affiliation(s)
- Giulia Faini
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Dimitrii Tanese
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Clément Molinier
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Cécile Telliez
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Massilia Hamdani
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Francois Blot
- 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
| | - Vincent de Sars
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Filippo Del Bene
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Benoît C Forget
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Emiliano Ronzitti
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France.
| | - Valentina Emiliani
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France.
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Spampinato GLB, Ronzitti E, Zampini V, Ferrari U, Trapani F, Khabou H, Agraval A, Dalkara D, Picaud S, Papagiakoumou E, Marre O, Emiliani V. All-optical inter-layers functional connectivity investigation in the mouse retina. Cell Rep Methods 2022; 2:100268. [PMID: 36046629 PMCID: PMC9421538 DOI: 10.1016/j.crmeth.2022.100268] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/03/2022] [Accepted: 07/19/2022] [Indexed: 06/01/2023]
Abstract
We developed a multi-unit microscope for all-optical inter-layers circuits interrogation. The system performs two-photon (2P) functional imaging and 2P multiplexed holographic optogenetics at axially distinct planes. We demonstrated the capability of the system to map, in the mouse retina, the functional connectivity between rod bipolar cells (RBCs) and ganglion cells (GCs) by activating single or defined groups of RBCs while recording the evoked response in the GC layer with cell-type specificity and single-cell resolution. We then used a logistic model to probe the functional connectivity between cell types by deriving the "cellular receptive field" describing how RBCs impact each GC type. With the capability to simultaneously image and control neuronal activity at axially distinct planes, the system enables a precise interrogation of multi-layered circuits. Understanding this information transfer is a promising avenue to dissect complex neural circuits and understand the neural basis of computations.
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Affiliation(s)
| | - Emiliano Ronzitti
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Valeria Zampini
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Ulisse Ferrari
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Francesco Trapani
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Hanen Khabou
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | | | - Deniz Dalkara
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | | | - Olivier Marre
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Valentina Emiliani
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
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Papagiakoumou E, Ronzitti E, Emiliani V. Scanless two-photon excitation with temporal focusing. Nat Methods 2020; 17:571-581. [PMID: 32284609 DOI: 10.1038/s41592-020-0795-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 02/28/2020] [Indexed: 11/09/2022]
Abstract
Temporal focusing, with its ability to focus light in time, enables scanless illumination of large surface areas at the sample with micrometer axial confinement and robust propagation through scattering tissue. In conventional two-photon microscopy, widely used for the investigation of intact tissue in live animals, images are formed by point scanning of a spatially focused pulsed laser beam, resulting in limited temporal resolution of the excitation. Replacing point scanning with temporally focused widefield illumination removes this limitation and represents an important milestone in two-photon microscopy. Temporal focusing uses a diffusive or dispersive optical element placed in a plane conjugate to the objective focal plane to generate position-dependent temporal pulse broadening that enables axially confined multiphoton absorption, without the need for tight spatial focusing. Many techniques have benefitted from temporal focusing, including scanless imaging, super-resolution imaging, photolithography, uncaging of caged neurotransmitters and control of neuronal activity via optogenetics.
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Affiliation(s)
- Eirini Papagiakoumou
- Wavefront-Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne University, Inserm S968, CNRS UMR7210, Fondation Voir et Entendre, Paris, France
| | - Emiliano Ronzitti
- Wavefront-Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne University, Inserm S968, CNRS UMR7210, Fondation Voir et Entendre, Paris, France
| | - Valentina Emiliani
- Wavefront-Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne University, Inserm S968, CNRS UMR7210, Fondation Voir et Entendre, Paris, France.
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Picot A, Dominguez S, Liu C, Chen IW, Tanese D, Ronzitti E, Berto P, Papagiakoumou E, Oron D, Tessier G, Forget BC, Emiliani V. Temperature Rise under Two-Photon Optogenetic Brain Stimulation. Cell Rep 2019; 24:1243-1253.e5. [PMID: 30067979 DOI: 10.1016/j.celrep.2018.06.119] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 03/26/2018] [Accepted: 06/28/2018] [Indexed: 10/28/2022] Open
Abstract
In recent decades, optogenetics has been transforming neuroscience research, enabling neuroscientists to drive and read neural circuits. The recent development in illumination approaches combined with two-photon (2P) excitation, either sequential or parallel, has opened the route for brain circuit manipulation with single-cell resolution and millisecond temporal precision. Yet, the high excitation power required for multi-target photostimulation, especially under 2P illumination, raises questions about the induced local heating inside samples. Here, we present and experimentally validate a theoretical model that makes it possible to simulate 3D light propagation and heat diffusion in optically scattering samples at high spatial and temporal resolution under the illumination configurations most commonly used to perform 2P optogenetics: single- and multi-spot holographic illumination and spiral laser scanning. By investigating the effects of photostimulation repetition rate, spot spacing, and illumination dependence of heat diffusion, we found conditions that make it possible to design a multi-target 2P optogenetics experiment with minimal sample heating.
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Affiliation(s)
- Alexis Picot
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
| | - Soledad Dominguez
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
| | - Chang Liu
- Holographic Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France; Sorbonne Université, CNRS, INSERM, Institut de la Vision, 17 Rue Moreau, 75011 Paris, France
| | - I-Wen Chen
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
| | - Dimitrii Tanese
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
| | - Emiliano Ronzitti
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France; Sorbonne Université, CNRS, INSERM, Institut de la Vision, 17 Rue Moreau, 75011 Paris, France
| | - Pascal Berto
- Holographic Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
| | - Eirini Papagiakoumou
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France; Institut National de la Santé et de la Recherche Médicale (Inserm), Paris, France
| | - Dan Oron
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Gilles Tessier
- Holographic Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France; Sorbonne Université, CNRS, INSERM, Institut de la Vision, 17 Rue Moreau, 75011 Paris, France
| | - Benoît C Forget
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
| | - Valentina Emiliani
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, UMR 8250 CNRS, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France.
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Ronzitti E, Emiliani V, Papagiakoumou E. Methods for Three-Dimensional All-Optical Manipulation of Neural Circuits. Front Cell Neurosci 2018; 12:469. [PMID: 30618626 PMCID: PMC6304748 DOI: 10.3389/fncel.2018.00469] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/19/2018] [Indexed: 12/18/2022] Open
Abstract
Optical means for modulating and monitoring neuronal activity, have provided substantial insights to neurophysiology and toward our understanding of how the brain works. Optogenetic actuators, calcium or voltage imaging probes and other molecular tools, combined with advanced microscopies have allowed an "all-optical" readout and modulation of neural circuits. Completion of this remarkable work is evolving toward a three-dimensional (3D) manipulation of neural ensembles at a high spatiotemporal resolution. Recently, original optical methods have been proposed for both activating and monitoring neurons in a 3D space, mainly through optogenetic compounds. Here, we review these methods and anticipate possible combinations among them.
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Affiliation(s)
| | | | - Eirini Papagiakoumou
- Wavefront Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne Université, Inserm S968, CNRS UMR7210, Paris, France
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Ronzitti E, Zampini V, Emiliani V. Optimized Chronos sets the clock for optogenetic hearing restoration. EMBO J 2018; 37:embj.2018101103. [PMID: 30509969 DOI: 10.15252/embj.2018101103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Emiliano Ronzitti
- Institut de la Vision, Inserm S968, CNRS UMR7210, Sorbonne University, Paris, France
| | - Valeria Zampini
- Institut de la Vision, Inserm S968, CNRS UMR7210, Sorbonne University, Paris, France
| | - Valentina Emiliani
- Institut de la Vision, Inserm S968, CNRS UMR7210, Sorbonne University, Paris, France
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Shemesh OA, Tanese D, Zampini V, Linghu C, Piatkevich K, Ronzitti E, Papagiakoumou E, Boyden ES, Emiliani V. Publisher Correction: Temporally precise single-cell-resolution optogenetics. Nat Neurosci 2018; 21:896. [PMID: 29549318 DOI: 10.1038/s41593-018-0097-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the supplementary information originally posted online, Supplementary Tables 1-5 and the Supplementary Note were missing. The error has been corrected online.
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Affiliation(s)
- Or A Shemesh
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.,Department of Biological Engineering, MIT, Cambridge, MA, USA.,Center for Neurobiological Engineering, MIT, Cambridge, MA, USA.,Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Dimitrii Tanese
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
| | - Valeria Zampini
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France.,Institut de la Vision, UM 80, UPMC, Paris, France
| | - Changyang Linghu
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.,Department of Biological Engineering, MIT, Cambridge, MA, USA.,Center for Neurobiological Engineering, MIT, Cambridge, MA, USA.,Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Kiryl Piatkevich
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.,Department of Biological Engineering, MIT, Cambridge, MA, USA.,Center for Neurobiological Engineering, MIT, Cambridge, MA, USA.,Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Emiliano Ronzitti
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France.,Institut de la Vision, UM 80, UPMC, Paris, France
| | - Eirini Papagiakoumou
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France.,Institut national de la santé et de la recherche médicale (Inserm), Paris, France
| | - Edward S Boyden
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA. .,Department of Biological Engineering, MIT, Cambridge, MA, USA. .,Center for Neurobiological Engineering, MIT, Cambridge, MA, USA. .,Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA. .,McGovern Institute for Brain Research, MIT, Cambridge, MA, USA.
| | - Valentina Emiliani
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France.
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Shemesh OA, Tanese D, Zampini V, Linghu C, Piatkevich K, Ronzitti E, Papagiakoumou E, Boyden ES, Emiliani V. Temporally precise single-cell-resolution optogenetics. Nat Neurosci 2017; 20:1796-1806. [PMID: 29184208 PMCID: PMC5726564 DOI: 10.1038/s41593-017-0018-8] [Citation(s) in RCA: 144] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/26/2017] [Indexed: 02/07/2023]
Abstract
Optogenetic control of individual neurons with high temporal precision within intact mammalian brain circuitry would enable powerful explorations of how neural circuits operate. Two-photon computer-generated holography enables precise sculpting of light and could in principle enable simultaneous illumination of many neurons in a network, with the requisite temporal precision to simulate accurate neural codes. We designed a high-efficacy soma-targeted opsin, finding that fusing the N-terminal 150 residues of kainate receptor subunit 2 (KA2) to the recently discovered high-photocurrent channelrhodopsin CoChR restricted expression of this opsin primarily to the cell body of mammalian cortical neurons. In combination with two-photon holographic stimulation, we found that this somatic CoChR (soCoChR) enabled photostimulation of individual cells in mouse cortical brain slices with single-cell resolution and <1-ms temporal precision. We used soCoChR to perform connectivity mapping on intact cortical circuits.
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Affiliation(s)
- Or A Shemesh
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Biological Engineering, MIT, Cambridge, MA, USA
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Dimitrii Tanese
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
| | - Valeria Zampini
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
- Institut de la Vision, UM 80, UPMC, Paris, France
| | - Changyang Linghu
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Biological Engineering, MIT, Cambridge, MA, USA
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Kiryl Piatkevich
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Biological Engineering, MIT, Cambridge, MA, USA
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Emiliano Ronzitti
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
- Institut de la Vision, UM 80, UPMC, Paris, France
| | - Eirini Papagiakoumou
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
- Institut national de la santé et de la recherche médicale (Inserm), Paris, France
| | - Edward S Boyden
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
- Department of Biological Engineering, MIT, Cambridge, MA, USA.
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA.
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA.
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA.
| | - Valentina Emiliani
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France.
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Ronzitti E, Conti R, Zampini V, Tanese D, Foust AJ, Klapoetke N, Boyden ES, Papagiakoumou E, Emiliani V. Submillisecond Optogenetic Control of Neuronal Firing with Two-Photon Holographic Photoactivation of Chronos. J Neurosci 2017; 37:10679-10689. [PMID: 28972125 DOI: 10.1101/062182] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 09/14/2017] [Accepted: 09/16/2017] [Indexed: 05/24/2023] Open
Abstract
Optogenetic neuronal network manipulation promises to unravel a long-standing mystery in neuroscience: how does microcircuit activity relate causally to behavioral and pathological states? The challenge to evoke spikes with high spatial and temporal complexity necessitates further joint development of light-delivery approaches and custom opsins. Two-photon (2P) light-targeting strategies demonstrated in-depth generation of action potentials in photosensitive neurons both in vitro and in vivo, but thus far lack the temporal precision necessary to induce precisely timed spiking events. Here, we show that efficient current integration enabled by 2P holographic amplified laser illumination of Chronos, a highly light-sensitive and fast opsin, can evoke spikes with submillisecond precision and repeated firing up to 100 Hz in brain slices from Swiss male mice. These results pave the way for optogenetic manipulation with the spatial and temporal sophistication necessary to mimic natural microcircuit activity.SIGNIFICANCE STATEMENT To reveal causal links between neuronal activity and behavior, it is necessary to develop experimental strategies to induce spatially and temporally sophisticated perturbation of network microcircuits. Two-photon computer generated holography (2P-CGH) recently demonstrated 3D optogenetic control of selected pools of neurons with single-cell accuracy in depth in the brain. Here, we show that exciting the fast opsin Chronos with amplified laser 2P-CGH enables cellular-resolution targeting with unprecedented temporal control, driving spiking up to 100 Hz with submillisecond onset precision using low laser power densities. This system achieves a unique combination of spatial flexibility and temporal precision needed to pattern optogenetically inputs that mimic natural neuronal network activity patterns.
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Affiliation(s)
- Emiliano Ronzitti
- Neurophotonics Laboratory, Wavefront Engineering Microscopy Group, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8250, Université Paris Descartes, 75270 Paris Cedex 06, France
| | - Rossella Conti
- Neurophotonics Laboratory, Wavefront Engineering Microscopy Group, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8250, Université Paris Descartes, 75270 Paris Cedex 06, France
| | - Valeria Zampini
- Neurophotonics Laboratory, Wavefront Engineering Microscopy Group, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8250, Université Paris Descartes, 75270 Paris Cedex 06, France
| | - Dimitrii Tanese
- Neurophotonics Laboratory, Wavefront Engineering Microscopy Group, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8250, Université Paris Descartes, 75270 Paris Cedex 06, France
| | - Amanda J Foust
- Neurophotonics Laboratory, Wavefront Engineering Microscopy Group, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8250, Université Paris Descartes, 75270 Paris Cedex 06, France
| | - Nathan Klapoetke
- Media Laboratory and McGovern Institute, Departments of Biological Engineering and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147
| | - Edward S Boyden
- Media Laboratory and McGovern Institute, Departments of Biological Engineering and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and
| | - Eirini Papagiakoumou
- Neurophotonics Laboratory, Wavefront Engineering Microscopy Group, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8250, Université Paris Descartes, 75270 Paris Cedex 06, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), 75013 Paris, France
| | - Valentina Emiliani
- Neurophotonics Laboratory, Wavefront Engineering Microscopy Group, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8250, Université Paris Descartes, 75270 Paris Cedex 06, France,
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12
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Chaigneau E, Ronzitti E, Gajowa MA, Soler-Llavina GJ, Tanese D, Brureau AYB, Papagiakoumou E, Zeng H, Emiliani V. Two-Photon Holographic Stimulation of ReaChR. Front Cell Neurosci 2016; 10:234. [PMID: 27803649 PMCID: PMC5067533 DOI: 10.3389/fncel.2016.00234] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/26/2016] [Indexed: 12/15/2022] Open
Abstract
Optogenetics provides a unique approach to remotely manipulate brain activity with light. Reaching the degree of spatiotemporal control necessary to dissect the role of individual cells in neuronal networks, some of which reside deep in the brain, requires joint progress in opsin engineering and light sculpting methods. Here we investigate for the first time two-photon stimulation of the red-shifted opsin ReaChR. We use two-photon (2P) holographic illumination to control the activation of individually chosen neurons expressing ReaChR in acute brain slices. We demonstrated reliable action potential generation in ReaChR-expressing neurons and studied holographic 2P-evoked spiking performances depending on illumination power and pulse width using an amplified laser and a standard femtosecond Ti:Sapphire oscillator laser. These findings provide detailed knowledge of ReaChR's behavior under 2P illumination paving the way for achieving in depth remote control of multiple cells with high spatiotemporal resolution deep within scattering tissue.
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Affiliation(s)
- Emmanuelle Chaigneau
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique UMR8250, Paris Descartes University Paris, France
| | - Emiliano Ronzitti
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique UMR8250, Paris Descartes University Paris, France
| | - Marta A Gajowa
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique UMR8250, Paris Descartes University Paris, France
| | | | - Dimitrii Tanese
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique UMR8250, Paris Descartes University Paris, France
| | - Anthony Y B Brureau
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique UMR8250, Paris Descartes University Paris, France
| | - Eirini Papagiakoumou
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique UMR8250, Paris Descartes UniversityParis, France; Institut National de la Santé et de la Recherche Médicale (INSERM)Paris, France
| | - Hongkui Zeng
- Allen Institute for Brain Science Seattle, WA, USA
| | - Valentina Emiliani
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique UMR8250, Paris Descartes University Paris, France
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13
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Lauterbach MA, Ronzitti E, Sternberg JR, Wyart C, Emiliani V. Fast Calcium Imaging with Optical Sectioning via HiLo Microscopy. PLoS One 2015; 10:e0143681. [PMID: 26625116 PMCID: PMC4666667 DOI: 10.1371/journal.pone.0143681] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Accepted: 11/09/2015] [Indexed: 11/18/2022] Open
Abstract
Imaging intracellular calcium concentration via reporters that change their fluorescence properties upon binding of calcium, referred to as calcium imaging, has revolutionized our way to probe neuronal activity non-invasively. To reach neurons densely located deep in the tissue, optical sectioning at high rate of acquisition is necessary but difficult to achieve in a cost effective manner. Here we implement an accessible solution relying on HiLo microscopy to provide robust optical sectioning with a high frame rate in vivo. We show that large calcium signals can be recorded from dense neuronal populations at high acquisition rates. We quantify the optical sectioning capabilities and demonstrate the benefits of HiLo microscopy compared to wide-field microscopy for calcium imaging and 3D reconstruction. We apply HiLo microscopy to functional calcium imaging at 100 frames per second deep in biological tissues. This approach enables us to discriminate neuronal activity of motor neurons from different depths in the spinal cord of zebrafish embryos. We observe distinct time courses of calcium signals in somata and axons. We show that our method enables to remove large fluctuations of the background fluorescence. All together our setup can be implemented to provide efficient optical sectioning in vivo at low cost on a wide range of existing microscopes.
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Affiliation(s)
- Marcel A. Lauterbach
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, CNRS UMR8250, University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Emiliano Ronzitti
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, CNRS UMR8250, University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jenna R. Sternberg
- Institut du Cerveau et de la Moelle Epinière (ICM), INSERM U1127, CNRS UMR 7225, Sorbonne Paris Cité, University Pierre et Marie Curie Paris 06 UMR S 1127, Paris, France
| | - Claire Wyart
- Institut du Cerveau et de la Moelle Epinière (ICM), INSERM U1127, CNRS UMR 7225, Sorbonne Paris Cité, University Pierre et Marie Curie Paris 06 UMR S 1127, Paris, France
| | - Valentina Emiliani
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, CNRS UMR8250, University Paris Descartes, Sorbonne Paris Cité, Paris, France
- * E-mail:
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Lavagnino Z, Zanacchi FC, Ronzitti E, Diaspro A. Two-photon excitation selective plane illumination microscopy (2PE-SPIM) of highly scattering samples: characterization and application. Opt Express 2013; 21:5998-6008. [PMID: 23482168 DOI: 10.1364/oe.21.005998] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In this work we report the advantages provided by two photon excitation (2PE) implemented in a selective plane illumination microscopy (SPIM) when imaging thick scattering samples. In particular, a detailed analysis of the effects induced on the real light sheet excitation intensity distribution is performed. The comparison between single-photon and two-photon excitation profiles shows the reduction of the scattering effects and sample-induced aberrations provided by 2PE-SPIM. Furthermore, uniformity of the excitation distribution and the consequent improved image contrast is shown when imaging scattering phantom samples in depth by 2PE-SPIM. These results show the advantages of 2PE-SPIM and suggest how this combination can further enhance the SPIM performance. Phantom samples have been designed with optical properties compatible with biological applications of interest.
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Affiliation(s)
- Zeno Lavagnino
- Department of Physics, University of Genoa, Via Dodecaneso 33, 16146 Genoa, Italy
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15
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Abstract
We present a novel concept adaptable to any kind of STED microscope in order to expand the limited number of compatible dyes for performing super resolution imaging. The approach is based on an intensity modulated excitation beam in combination with a frequency dependent detection in the form of a standard lock-in amplifier. This enables to unmix fluorescence signal originated by the excitation beam from the fluorescence caused by the STED beam. The benefit of this concept is demonstrated by imaging biological samples as well as fluorescent spheres, whose spectrum does not allow STED imaging in the conventional way. Our concept is suitable with CW or pulsed STED microscope and can thereby be seen as a general improvement adaptable to any existing setup.
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16
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Ronzitti E, Guillon M, de Sars V, Emiliani V. LCoS nematic SLM characterization and modeling for diffraction efficiency optimization, zero and ghost orders suppression. Opt Express 2012; 20:17843-55. [PMID: 23038335 DOI: 10.1364/oe.20.017843] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Pixilated spatial light modulators are efficient devices to shape the wavefront of a laser beam or to perform Fourier optical filtering. When conjugated with the back focal plane of a microscope objective, they allow an efficient redistribution of laser light energy. These intensity patterns are usually polluted by undesired spots so-called ghosts and zero-orders whose intensities depend on displayed patterns. In this work, we propose a model to account for these discrepancies and demonstrate the possibility to efficiently reduce the intensity of the zero-order up to 95%, the intensity of the ghost up to 96% and increase diffraction efficiency up to 44%. Our model suggests physical cross-talk between pixels and thus, filtering of addressed high spatial frequencies. The method implementation relies on simple preliminary characterization of the SLM and can be computed a priori with any phase profile. The performance of this method is demonstrated employing a Hamamatsu LCoS SLM X10468-02 with two-photon excitation of fluorescent Rhodamine layers.
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Affiliation(s)
- Emiliano Ronzitti
- Laboratory of Neurophysiology and New Microscopies, Wavefront Engineering group (INSERM S603, CNRS UMR 8154), Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints Pères, 75006 Paris, France
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17
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Cella Zanacchi F, Lavagnino Z, Ronzitti E, Vicidomini G, Usai C, Diaspro A. 3D Imaging by Multiphoton Selective Plane Illumination. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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18
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Lavagnino Z, Cella Zanacchi F, Ronzitti E, Coto Hernandez I, Diaspro A. Characterization of Scattering Effects in Phantom Samples using Single and Two-Photon Excitation Light Sheet Microscopy. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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19
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Bruzzone F, Cervetto C, Mazzotta M, Bianchini P, Ronzitti E, Leprince J, Diaspro A, Maura G, Vallarino M, Vaudry H, Marcoli M. Urotensin II receptor and acetylcholine release from mouse cervical spinal cord nerve terminals. Neuroscience 2010; 170:67-77. [DOI: 10.1016/j.neuroscience.2010.06.070] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 06/16/2010] [Accepted: 06/25/2010] [Indexed: 01/30/2023]
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20
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Diaspro A, Bianchini P, Cella F, Ronzitti E, Galiani S, Pesce M, Lavagnino Z, Abdelrasoul G. Optical Nanoscopy Far-Field Approaches to Cellular and Molecular Biophysics. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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21
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Ronzitti E, Vicidomini G, Caorsi V, Diaspro A. Annular pupil filter under shot-noise condition for linear and non linear microscopy. Opt Express 2009; 17:6867-6880. [PMID: 19365514 DOI: 10.1364/oe.17.006867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The imaging performances of multiphoton excitation and confocal laser scanning microscopy are herby considered: in typical experimental imaging conditions, a small finite amount of photon reaches the detector giving shot-noise fluctuations which affects the signal acquired. A significant detriment in the high frequencies transmission capability is obtained. In order to partially recover the high frequencies information lost, the insertion of a pupil plane filter in the microscope illumination light pathway on the objective lens is proposed. We demonstrate high-frequency and resolution enhancement in the case of linear and non linear fluorescence microscope approach under shot-noise condition.
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Affiliation(s)
- Emiliano Ronzitti
- LAMBS-IFOM, MicroScoBio, Department of Physics, University of Genoa, Via Dodecaneso, 16145 Genoa, Italy.
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22
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Ronzitti E, Caorsi V, Diaspro A. Nanostructured polyelectrolyte-based system as a toolbox for metal ions detection. J Fluoresc 2007; 18:375-81. [PMID: 18097740 DOI: 10.1007/s10895-007-0277-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Accepted: 10/22/2007] [Indexed: 11/25/2022]
Abstract
The capability of certain heavy metal ions to induce fluorescence decrease by a quenching mechanism suggested us to design and build a sensor potentially tunable for different ions at different concentrations. We propose a quenching-based sensor exploiting a nanostructured architecture in which fluorescent molecules (the sensing probe) are entrapped to recognize a specific analyte (heavy metal ions) through an optical transduction. The polyelectrolyte nanostructured system, named nanocapsule, improves the fluorophore-ion quenching sensitivity allowing a micromolar detection. Furthermore we couple our sensor with an electrical device in order to refine the sensing procedure: the electric field created allows a metal ions spatial gradient, necessary to detect a specific element on a single sample solution, avoiding a comparative analysis with an intensity reference value. Results obtained will show the advantages and the potentialities of our system as a smart toolbox for metal ions detection.
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Affiliation(s)
- Emiliano Ronzitti
- LAMBS-IFOM, MicroScoBio Research Center, Department of Physics (DIFI), University of Genoa, Via Dodecaneso 33, Genoa, Italy.
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Abstract
In the last decade, fluorescence resonance energy transfer (FRET) has become a useful technique for studying intermolecular interactions applied to the analysis of biological systems. Although FRET measurements may be very helpful in the comprehension of different cellular processes, it can be difficult to obtain quantitative results, hence the necessity of studying FRET on controllable systems. Here, a fuzzy nanostructured system called a nanocapsule is presented as a nanometric-device allowing distance modulation, thus preserving photophysical properties of fluorescent dyes and exhibiting good potential features for improving quantitative FRET analysis. We evaluated the behavior of such a sample using four FRET methods (three of them based on steady-state fluorescence and one using lifetime measurements). Within some limitations that can be overcome, these nanodevices have the potential to serve as a benchmark system for characterizing new FRET couples and to develop quantitative approaches for FRET analysis.
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Affiliation(s)
- V Caorsi
- LAMBS, MicroScoBIO Research Center, Department of Physics (DIFI), University of Genoa, Genoa, Italy.
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