14 results on '"M, Ducros"'
Search Results
2. Essai de regionalisation de l'economie francaise en 1985 en trois grandes zones geographiques
- Author
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P. Vr., M. Ducros, and M. Fraisse
- Subjects
Demography - Published
- 1969
- Full Text
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Catalog
3. Understanding the nervous system: lessons from Frontiers in Neurophotonics.
- Author
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De Koninck Y, Alonso J, Bancelin S, Béïque JC, Bélanger E, Bouchard C, Canossa M, Chaniot J, Choquet D, Crochetière MÈ, Cui N, Danglot L, De Koninck P, Devor A, Ducros M, Getz AM, Haouat M, Hernández IC, Jowett N, Keramidis I, Larivière-Loiselle C, Lavoie-Cardinal F, MacGillavry HD, Malkoç A, Mancinelli M, Marquet P, Minderler S, Moreaud M, Nägerl UV, Papanikolopoulou K, Paquet ME, Pavesi L, Perrais D, Sansonetti R, Thunemann M, Vignoli B, Yau J, and Zaccaria C more...
- Abstract
The Frontiers in Neurophotonics Symposium is a biennial event that brings together neurobiologists and physicists/engineers who share interest in the development of leading-edge photonics-based approaches to understand and manipulate the nervous system, from its individual molecular components to complex networks in the intact brain. In this Community paper, we highlight several topics that have been featured at the symposium that took place in October 2022 in Québec City, Canada., (© 2024 The Authors.) more...
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- 2024
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4. Shadow imaging for panoptical visualization of brain tissue in vivo.
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Dembitskaya Y, Boyce AKJ, Idziak A, Pourkhalili Langeroudi A, Arizono M, Girard J, Le Bourdellès G, Ducros M, Sato-Fitoussi M, Ochoa de Amezaga A, Oizel K, Bancelin S, Mercier L, Pfeiffer T, Thompson RJ, Kim SK, Bikfalvi A, and Nägerl UV more...
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- Mice, Animals, Microscopy, Fluorescence methods, Extracellular Space, Head, Brain diagnostic imaging, Neurons
- Abstract
Progress in neuroscience research hinges on technical advances in visualizing living brain tissue with high fidelity and facility. Current neuroanatomical imaging approaches either require tissue fixation (electron microscopy), do not have cellular resolution (magnetic resonance imaging) or only give a fragmented view (fluorescence microscopy). Here, we show how regular light microscopy together with fluorescence labeling of the interstitial fluid in the extracellular space provide comprehensive optical access in real-time to the anatomical complexity and dynamics of living brain tissue at submicron scale. Using several common fluorescence microscopy modalities (confocal, light-sheet and 2-photon microscopy) in mouse organotypic and acute brain slices and the intact mouse brain in vivo, we demonstrate the value of this straightforward 'shadow imaging' approach by revealing neurons, microglia, tumor cells and blood capillaries together with their complete anatomical tissue contexts. In addition, we provide quantifications of perivascular spaces and the volume fraction of the extracellular space of brain tissue in vivo., (© 2023. Springer Nature Limited.) more...
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- 2023
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5. Active image optimization for lattice light sheet microscopy in thick samples.
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Malivert M, Harms F, Veilly C, Legrand J, Li Z, Bayer E, Choquet D, and Ducros M
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Lattice light-sheet microscopy (LLSM) is a very efficient technique for high resolution 3D imaging of dynamic phenomena in living biological samples. However, LLSM imaging remains limited in depth due to optical aberrations caused by sample-based refractive index mismatch. Here, we propose a simple and low-cost active image optimization (AIO) method to recover high resolution imaging inside thick biological samples. AIO is based on (1) a light-sheet autofocus step (AF) followed by (2) an adaptive optics image-based optimization. We determine the optimum AIO parameters to provide a fast, precise and robust aberration correction on biological samples. Finally, we demonstrate the performances of our approach on sub-micrometric structures in brain slices and plant roots., Competing Interests: MM, FH, CV, JL: Imagine Optic (E), (© 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.) more...
- Published
- 2022
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6. High-resolution imaging and manipulation of endogenous AMPA receptor surface mobility during synaptic plasticity and learning.
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Getz AM, Ducros M, Breillat C, Lampin-Saint-Amaux A, Daburon S, François U, Nowacka A, Fernández-Monreal M, Hosy E, Lanore F, Zieger HL, Sainlos M, Humeau Y, and Choquet D
- Abstract
Regulation of synaptic neurotransmitter receptor content is a fundamental mechanism for tuning synaptic efficacy during experience-dependent plasticity and behavioral adaptation. However, experimental approaches to track and modify receptor movements in integrated experimental systems are limited. Exploiting AMPA-type glutamate receptors (AMPARs) as a model, we generated a knock-in mouse expressing the biotin acceptor peptide (AP) tag on the GluA2 extracellular N-terminal. Cell-specific introduction of biotin ligase allows the use of monovalent or tetravalent avidin variants to respectively monitor or manipulate the surface mobility of endogenous AMPAR containing biotinylated AP-GluA2 in neuronal subsets. AMPAR immobilization precluded the expression of long-term potentiation and formation of contextual fear memory, allowing target-specific control of the expression of synaptic plasticity and animal behavior. The AP tag knock-in model offers unprecedented access to resolve and control the spatiotemporal dynamics of endogenous receptors, and opens new avenues to study the molecular mechanisms of synaptic plasticity and learning. more...
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- 2022
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7. Encoded multisite two-photon microscopy.
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Ducros M, Goulam Houssen Y, Bradley J, de Sars V, and Charpak S
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- Algorithms, Animals, Blood Flow Velocity, Brain blood supply, Brain cytology, Calcium metabolism, Calcium Signaling, HEK293 Cells, Humans, Image Processing, Computer-Assisted instrumentation, Image Processing, Computer-Assisted methods, Liquid Crystals, Mice, Mice, Inbred C57BL, Microscopy, Confocal instrumentation, Microscopy, Confocal methods, Models, Statistical, Reproducibility of Results, Time Factors, Brain metabolism, Microscopy, Fluorescence, Multiphoton instrumentation, Microscopy, Fluorescence, Multiphoton methods, Neurons metabolism
- Abstract
The advent of scanning two-photon microscopy (2PM) has created a fertile new avenue for noninvasive investigation of brain activity in depth. One principal weakness of this method, however, lies with the limit of scanning speed, which makes optical interrogation of action potential-like activity in a neuronal network problematic. Encoded multisite two-photon microscopy (eMS2PM), a scanless method that allows simultaneous imaging of multiple targets in depth with high temporal resolution, addresses this drawback. eMS2PM uses a liquid crystal spatial light modulator to split a high-power femto-laser beam into multiple subbeams. To distinguish them, a digital micromirror device encodes each subbeam with a specific binary amplitude modulation sequence. Fluorescence signals from all independently targeted sites are then collected simultaneously onto a single photodetector and site-specifically decoded. We demonstrate that eMS2PM can be used to image spike-like voltage transients in cultured cells and fluorescence transients (calcium signals in neurons and red blood cells in capillaries from the cortex) in depth in vivo. These results establish eMS2PM as a unique method for simultaneous acquisition of neuronal network activity. more...
- Published
- 2013
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8. Simultaneous two-photon imaging of oxygen and blood flow in deep cerebral vessels.
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Lecoq J, Parpaleix A, Roussakis E, Ducros M, Goulam Houssen Y, Vinogradov SA, and Charpak S
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- Animals, Capillaries metabolism, Cerebral Arteries metabolism, Cerebral Arteries physiology, Cerebral Veins metabolism, Cerebral Veins physiology, Luminescent Measurements methods, Olfactory Bulb blood supply, Olfactory Bulb metabolism, Olfactory Perception physiology, Partial Pressure, Rats, Rats, Wistar, Cerebrovascular Circulation physiology, Microscopy, Fluorescence, Multiphoton methods, Oxygen metabolism
- Abstract
Uncovering principles that regulate energy metabolism in the brain requires mapping of partial pressure of oxygen (PO(2)) and blood flow with high spatial and temporal resolution. Using two-photon phosphorescence lifetime microscopy (2PLM) and the oxygen probe PtP-C343, we show that PO(2) can be accurately measured in the brain at depths up to 300 μm with micron-scale resolution. In addition, 2PLM allowed simultaneous measurements of blood flow and of PO(2) in capillaries with less than one-second temporal resolution. Using this approach, we detected erythrocyte-associated transients (EATs) in oxygen in the rat olfactory bulb and showed the existence of diffusion-based arterio-venous shunts. Sensory stimulation evoked functional hyperemia, accompanied by an increase in PO(2) in capillaries and by a biphasic PO(2) response in the neuropil, consisting of an 'initial dip' and a rebound. 2PLM of PO(2) opens new avenues for studies of brain metabolism and blood flow regulation. more...
- Published
- 2011
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9. Spectral unmixing: analysis of performance in the olfactory bulb in vivo.
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Ducros M, Moreaux L, Bradley J, Tiret P, Griesbeck O, and Charpak S
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- Animals, Cells, Cultured, Humans, Mice, Mice, Transgenic, Microscopy, Confocal, Recombinant Fusion Proteins, Fluorescence Resonance Energy Transfer methods, Olfactory Bulb metabolism
- Abstract
Background: The generation of transgenic mice expressing combinations of fluorescent proteins has greatly aided the reporting of activity and identification of specific neuronal populations. Methods capable of separating multiple overlapping fluorescence emission spectra, deep in the living brain, with high sensitivity and temporal resolution are therefore required. Here, we investigate to what extent spectral unmixing addresses these issues., Methodology/principal Findings: Using fluorescence resonance energy transfer (FRET)-based reporters, and two-photon laser scanning microscopy with synchronous multichannel detection, we report that spectral unmixing consistently improved FRET signal amplitude, both in vitro and in vivo. Our approach allows us to detect odor-evoked FRET transients 180-250 microm deep in the brain, the first demonstration of in vivo spectral imaging and unmixing of FRET signals at depths greater than a few tens of micrometer. Furthermore, we determine the reporter efficiency threshold for which FRET detection is improved by spectral unmixing., Conclusions/significance: Our method allows the detection of small spectral variations in depth in the living brain, which is essential for imaging efficiently transgenic animals expressing combination of multiple fluorescent proteins. more...
- Published
- 2009
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10. Effective and structural connectivity in the human auditory cortex.
- Author
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Upadhyay J, Silver A, Knaus TA, Lindgren KA, Ducros M, Kim DS, and Tager-Flusberg H
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- Acoustic Stimulation methods, Adolescent, Adult, Auditory Cortex blood supply, Functional Laterality, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Neural Pathways blood supply, Oxygen blood, Auditory Cortex physiology, Brain Mapping, Neural Pathways physiology
- Abstract
Language processing involves multiple neuronal structures in the human auditory cortex. Although a variety of neuroimaging and mapping techniques have been implemented to better understand language processing at the level of the auditory cortex, much is unknown regarding how and by what pathways these structures interact during essential tasks such as sentence comprehension. In this study, the effective and structural connectivity at the level of the auditory cortex were investigated. First, blood oxygenation level-dependent (BOLD) responses were measured with time-resolved functional magnetic resonance imaging (fMRI) during audition of short sentences. Once BOLD activation maps were obtained, the effective connectivity between primary auditory cortex and the surrounding auditory regions on the supratemporal plane and superior temporal gyrus (STG) were investigated using Granger causality mapping (GCM). Effective connectivity was observed between the primary auditory cortex and (1) the lateral planum polare and anterior STG, and (2) the lateral planum temporale and posterior STG. By using diffusion tensor probabilistic mapping (DTPM), rostral and caudal fiber pathways were detected between regions depicting effective connectivity. The effective and structural connectivity results of the present study provide further insight as to how auditory stimuli (i.e., human language) is processed at the level of the auditory cortex. Furthermore, combining BOLD fMRI-based GCM and DTPM analysis could provide a novel means to study effective and structural connectivity not only in the auditory cortex, but also in other cortical regions. more...
- Published
- 2008
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11. Function and connectivity in human primary auditory cortex: a combined fMRI and DTI study at 3 Tesla.
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Upadhyay J, Ducros M, Knaus TA, Lindgren KA, Silver A, Tager-Flusberg H, and Kim DS
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- Acoustic Stimulation, Auditory Cortex anatomy & histology, Brain Mapping, Diffusion Magnetic Resonance Imaging, Humans, Magnetic Resonance Imaging, Nerve Fibers physiology, Probability, Software, Auditory Cortex physiology
- Abstract
Human primary auditory cortex (PAC) is functionally organized in a tonotopic manner. Past studies have used neuroimaging to characterize tonotopic organization in PAC and found similar organization as that described in mammals. In contrast to what is known about PAC in primates and nonprimates, in humans, the structural connectivity within PAC has not been defined. In this study, stroboscopic event-related functional magnetic resonance imaging (fMRI) was utilized to reveal mirror symmetric tonotopic organization consisting of a high-low-high frequency gradient in PAC. Furthermore, diffusion tensor tractography and probabilistic mapping was used to study projection patterns within tonotopic areas. Based on earlier physiological and histological work in nonhuman PAC, we hypothesized the existence of cross-field isofrequency (homotopic) and within-field non-isofrequency (heterotopic)-specific axonal projections in human PAC. The presence of both projections types was found in all subjects. Specifically, the number of diffusion tensor imaging (DTI) reconstructed fibers projecting between high- and low-frequency regions was greater than those fibers projecting between 2 high-frequency areas, the latter of which are located in distinct auditory fields. The fMRI and DTI results indicate that functional and structural properties within early stages of the auditory processing stream are preserved across multiple mammalian species at distinct evolutionary levels. more...
- Published
- 2007
- Full Text
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12. The relationship between blood flow and neuronal activity in the rodent olfactory bulb.
- Author
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Chaigneau E, Tiret P, Lecoq J, Ducros M, Knöpfel T, and Charpak S
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- 2-Amino-5-phosphonovalerate pharmacology, Age Factors, Animals, Animals, Newborn, Benzaldehydes pharmacology, Blood Circulation Time, Calcium metabolism, Excitatory Amino Acid Antagonists pharmacology, In Vitro Techniques, Long-Term Potentiation genetics, Long-Term Potentiation physiology, Mice, Mice, Transgenic, Microscopy, Confocal methods, Neurons drug effects, Odorants, Patch-Clamp Techniques methods, Quinoxalines pharmacology, Rats, Rats, Wistar, Tetrodotoxin pharmacology, Cerebrovascular Circulation physiology, Glomerular Mesangium physiology, Neurons physiology, Olfactory Bulb cytology
- Abstract
In the brain, neuronal activation triggers an increase in cerebral blood flow (CBF). Here, we use two animal models and several techniques (two-photon imaging of CBF and neuronal calcium dynamics, intracellular and extracellular recordings, local pharmacology) to analyze the relationship between neuronal activity and local CBF during odor stimulation in the rodent olfactory bulb. Application of glutamate receptor antagonists or tetrodotoxin directly into single rat olfactory glomeruli blocked postsynaptic responses but did not affect the local odor-evoked CBF increases. This suggests that in our experimental conditions, odor always activates more than one glomerulus and that silencing one of a few clustered glomeruli does not affect the vascular response. To block synaptic transmission more widely, we then superfused glutamate antagonists over the surface of the olfactory bulb in transgenic G-CaMP2 mice. This was for two reasons: (1) mice have a thin olfactory nerve layer compared to rats and this will favor drug access to the glomerular layer, and (2) transgenic G-CaMP2 mice express the fluorescent calcium sensor protein G-CaMP2 in mitral cells. In G-CaMP2 mice, odor-evoked, odor-specific, and concentration-dependent calcium increases in glomeruli. Superfusion of glutamate receptor antagonists blocked odor-evoked postsynaptic calcium signals and CBF responses. We conclude that activation of postsynaptic glutamate receptors and rises in dendritic calcium are major steps for neurovascular coupling in olfactory bulb glomeruli. more...
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- 2007
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13. 3-D diffusion tensor axonal tracking shows distinct SMA and pre-SMA projections to the human striatum.
- Author
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Lehéricy S, Ducros M, Krainik A, Francois C, Van de Moortele PF, Ugurbil K, and Kim DS
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- Adult, Corpus Striatum anatomy & histology, Female, Humans, Male, Motor Cortex anatomy & histology, Neural Pathways anatomy & histology, Neural Pathways physiology, Axons physiology, Corpus Striatum physiology, Echo-Planar Imaging methods, Imaging, Three-Dimensional methods, Motor Cortex physiology
- Abstract
Studies in non-human primates have shown that medial premotor projections to the striatum are characterized as a set of distinct circuits conveying different type of information. This study assesses the anatomical projections from the supplementary motor area (SMA), pre-SMA and motor cortex (MC) to the human striatum using diffusion tensor imaging (DTI) axonal tracking. Eight right-handed volunteers were studied at 1.5 T using DTI axonal tracking. A connectivity matrix was computed, which tested for connections between cortical areas (MC, SMA and pre-SMA) and subcortical areas (posterior, middle and anterior putamen and the head of the caudate nucleus) in each hemisphere. Pre-SMA projections to the striatum were located rostral to SMA projections to the striatum. The SMA and the MC were similarly connected to the posterior and middle putamen and not to the anterior striatum. These data show that the MC and SMA have connections with similar parts of the sensorimotor compartment of the human striatum, whereas the pre-SMA sends connections to more rostral parts of the striatum, including the associative compartment. more...
- Published
- 2004
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14. Video-rate three-dimensional optical coherence tomography.
- Author
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Laubscher M, Ducros M, Karamata B, Lasser T, and Salathe R
- Abstract
Most current optical coherence tomography systems provide two-dimensional cross-sectional or en face images. Successive adjacent images have to be acquired to reconstruct three-dimensional objects, which can be time consuming. Here we demonstrate three-dimensional optical coherence tomography (3D OCT) at video rate. A 58 by 58 smart-pixel detector array was employed. A sample volume of 210x210x80 m3 (corresponding to 58x58x58 voxels) was imaged at 25 Hz. The longitudinal and transverse resolutions are 3 m and 9 m respectively. The sensitivity of the system was 76 dB. Video rate 3D OCT is illustrated by movies of a strand of hair undergoing fast thermal damage. more...
- Published
- 2002
- Full Text
- View/download PDF
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