501
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Gurden H, Uchida N, Mainen ZF. Sensory-evoked intrinsic optical signals in the olfactory bulb are coupled to glutamate release and uptake. Neuron 2007; 52:335-45. [PMID: 17046695 DOI: 10.1016/j.neuron.2006.07.022] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 06/08/2006] [Accepted: 07/25/2006] [Indexed: 10/24/2022]
Abstract
Functional imaging signals arise from metabolic and hemodynamic activity, but how these processes are related to the synaptic and electrical activity of neurons is not well understood. To provide insight into this issue, we used in vivo imaging and simultaneous local pharmacology to study how sensory-evoked neural activity leads to intrinsic optical signals (IOS) in the well-defined circuitry of the olfactory glomerulus. Odor-evoked IOS were tightly coupled to release of glutamate and were strongly modulated by activation of presynaptic dopamine and GABA-B receptors. Surprisingly, IOS were independent of postsynaptic transmission through ionotropic or metabotropic glutamate receptors, but instead were inhibited when uptake by astrocytic glutamate transporters was blocked. These data suggest that presynaptic glutamate release and uptake by astrocytes form a critical pathway through which neural activity is linked to metabolic processing and hence to functional imaging signals.
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Affiliation(s)
- Hirac Gurden
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York, 11724, USA
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502
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Nishimura N, Schaffer CB, Friedman B, Lyden PD, Kleinfeld D. Penetrating arterioles are a bottleneck in the perfusion of neocortex. Proc Natl Acad Sci U S A 2006; 104:365-70. [PMID: 17190804 PMCID: PMC1765467 DOI: 10.1073/pnas.0609551104] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Penetrating arterioles bridge the mesh of communicating arterioles on the surface of cortex with the subsurface microvascular bed that feeds the underlying neural tissue. We tested the conjecture that penetrating arterioles, which are positioned to regulate the delivery of blood, are loci of severe ischemia in the event of occlusion. Focal photothrombosis was used to occlude single penetrating arterioles in rat parietal cortex, and the resultant changes in flow of red blood cells were measured with two-photon laser-scanning microscopy in individual subsurface microvessels that surround the occlusion. We observed that the average flow of red blood cells nearly stalls adjacent to the occlusion and remains within 30% of its baseline value in vessels as far as 10 branch points downstream from the occlusion. Preservation of average flow emerges 350 mum away; this length scale is consistent with the spatial distribution of penetrating arterioles. We conclude that penetrating arterioles are a bottleneck in the supply of blood to neocortex, at least to superficial layers.
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Affiliation(s)
- Nozomi Nishimura
- Departments of *Physics and
- Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, CA 92093
| | - Chris B. Schaffer
- Departments of *Physics and
- Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, CA 92093
| | | | | | - David Kleinfeld
- Departments of *Physics and
- Graduate Program in Neurosciences, and
- Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, CA 92093
- To whom correspondence should be addressed. E-mail:
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503
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Göbel W, Kampa BM, Helmchen F. Imaging cellular network dynamics in three dimensions using fast 3D laser scanning. Nat Methods 2006; 4:73-9. [PMID: 17143280 DOI: 10.1038/nmeth989] [Citation(s) in RCA: 223] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Accepted: 11/01/2006] [Indexed: 11/09/2022]
Abstract
Spatiotemporal activity patterns in three-dimensionally organized cellular networks are fundamental to the function of the nervous system. Despite advances in functional imaging of cell populations, a method to resolve local network activity in three dimensions has been lacking. Here we introduce a three-dimensional (3D) line-scan technology for two-photon microscopy that permits fast fluorescence measurements from several hundred cells distributed in 3D space. We combined sinusoidal vibration of the microscope objective at 10 Hz with 'smart' movements of galvanometric x-y scanners to repeatedly scan the laser focus along a closed 3D trajectory. More than 90% of cell somata were sampled by the scan line within volumes of 250 microm side length. Using bulk-loading of calcium indicator, we applied this method to reveal spatiotemporal activity patterns in neuronal and astrocytic networks in the rat neocortex in vivo. Two-photon population imaging using 3D scanning opens the field for comprehensive studies of local network dynamics in intact tissue.
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Affiliation(s)
- Werner Göbel
- Department of Neurophysiology, Brain Research Institute, University of Zurich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland
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504
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Aguirre AD, Chen Y, Fujimoto JG, Ruvinskaya L, Devor A, Boas DA. Depth-resolved imaging of functional activation in the rat cerebral cortex using optical coherence tomography. OPTICS LETTERS 2006; 31:3459-61. [PMID: 17099749 PMCID: PMC2293976 DOI: 10.1364/ol.31.003459] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Co-registered optical coherence tomography (OCT) and video microscopy of the rat somatosensory cortex were acquired simultaneously through a thinned skull during forepaw electrical stimulation. Fractional signal change measured by OCT revealed a functional signal time course corresponding to the hemodynamic signal measurement made with video microscopy. OCT can provide high-resolution, cross-sectional images of functional neurovascular activation and may offer a new tool for basic neuroscience research in the important rat cerebral cortex model.
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Affiliation(s)
- A D Aguirre
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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505
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Theer P, Denk W. On the fundamental imaging-depth limit in two-photon microscopy. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2006; 23:3139-49. [PMID: 17106469 DOI: 10.1364/josaa.23.003139] [Citation(s) in RCA: 226] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We have analyzed how the maximal imaging depth of two-photon microscopy in scattering samples depends on properties of the sample and the imaging system. We find that the imaging depth increases with increasing numerical aperture and staining inhomogeneity and with decreasing excitation-pulse duration and scattering anisotropy factor, but is ultimately limited by near-surface fluorescence with slight improvements possible using special detection strategies.
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Affiliation(s)
- Patrick Theer
- Max-Planck Institute for Medical Research, Heidelberg, Germany.
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506
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507
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Rueckel M, Mack-Bucher JA, Denk W. Adaptive wavefront correction in two-photon microscopy using coherence-gated wavefront sensing. Proc Natl Acad Sci U S A 2006; 103:17137-42. [PMID: 17088565 PMCID: PMC1634839 DOI: 10.1073/pnas.0604791103] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The image quality of a two-photon microscope is often degraded by wavefront aberrations induced by the specimen. We demonstrate here that resolution and signal size in two-photon microcopy can be substantially improved, even in living biological specimens, by adaptive wavefront correction based on sensing the wavefront of coherence-gated backscattered light (coherence-gated wavefront sensing, CGWS) and wavefront control by a deformable mirror. A nearly diffraction-limited focus can be restored even for strong aberrations. CGWS-based wavefront correction should be applicable to samples with a wide range of scattering properties and it should be possible to perform real-time pixel-by-pixel correction even at fast scan speeds.
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Affiliation(s)
- Markus Rueckel
- Department of Biomedical Optics, Max-Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany.
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508
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Garai K, Muralidhar M, Maiti S. Fiber-optic fluorescence correlation spectrometer. APPLIED OPTICS 2006; 45:7538-42. [PMID: 16983444 DOI: 10.1364/ao.45.007538] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Fluorescence correlation spectroscopy (FCS) is a sensitive technique used to probe size, concentration, flow velocity, and reaction kinetics in a dilute solution. Conventional FCS spectrometers achieve this sensitivity at the cost of using bulky optics. We demonstrate a technique that utilizes a single-mode optical fiber of 3.3 microm mode field diameter to perform FCS measurements. We demonstrate that the technique has adequate sensitivity to perform FCS measurements on fluorescent beads of 13 nm radius, and that the results agree with theoretical predictions. Our method potentially allows FCS to be extended to remote and in vivo applications.
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Affiliation(s)
- Kanchan Garai
- Tata Institute of Fundamental Research, Colaba, Mumbai, India
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509
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Martin C, Martindale J, Berwick J, Mayhew J. Investigating neural–hemodynamic coupling and the hemodynamic response function in the awake rat. Neuroimage 2006; 32:33-48. [PMID: 16725349 DOI: 10.1016/j.neuroimage.2006.02.021] [Citation(s) in RCA: 206] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 12/16/2005] [Accepted: 02/20/2006] [Indexed: 10/24/2022] Open
Abstract
An understanding of the relationship between changes in neural activity and the accompanying hemodynamic response is crucial for accurate interpretation of functional brain imaging data and in particular the blood oxygen level-dependent (BOLD) fMRI signal. Much physiological research investigating this topic uses anesthetized animal preparations, and yet, the effects of anesthesia upon the neural and hemodynamic responses measured in such studies are not well understood. In this study, we electrically stimulated the whisker pad of both awake and urethane anesthetized rats at frequencies of 1-40 Hz. Evoked field potential responses were recorded using electrodes implanted into the contralateral barrel cortex. Changes in hemoglobin oxygenation and concentration were measured using optical imaging spectroscopy, and cerebral blood flow changes were measured using laser Doppler flowmetry. A linear neural-hemodynamic coupling relationship was found in the awake but not the anesthetized animal preparation. Over the range of stimulation conditions studied, hemodynamic response magnitude increased monotonically with summed neural activity in awake, but not in anesthetized, animals. Additionally, the temporal structure of the hemodynamic response function was different in awake compared to anesthetized animals. The responses in each case were well approximated by gamma variates, but these were different in terms of mean latency (approximately 2 s awake; 4 s anesthetized) and width (approximately 0.6 s awake; 2.5 s anesthetized). These findings have important implications for research into the intrinsic signals that underpin BOLD fMRI and for biophysical models of cortical hemodynamics and neural-hemodynamic coupling.
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Affiliation(s)
- Chris Martin
- SPiNSN, Department of Psychology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
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510
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Baborie A, Kuschinsky W. Lack of relationship between cellular density and either capillary density or metabolic rate in different regions of the brain. Neurosci Lett 2006; 404:20-2. [PMID: 16730903 DOI: 10.1016/j.neulet.2006.05.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 04/11/2006] [Accepted: 05/05/2006] [Indexed: 11/16/2022]
Abstract
Whereas a pronounced correlation exists between local cerebral glucose utilization (LCGU) and capillary density in different regions of the brain, it is not known whether these parameters also correlate with the overall density of nuclei (cellularity). Therefore, cellularity was determined by diamidino-phenylindol (DAPI) fluorescent staining of nuclei in acetone-fixed frozen sections of the rat brain. A comparison of the density of nuclei in different brain regions showed much less variation than that observed in LCGU and capillary density. No correlation was found between nuclear density and either LCGU or capillary densities. In conclusion the cellular density is not a determinant of variation in LCGU and capillary density.
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Affiliation(s)
- Atik Baborie
- Department of Neuropathology, Newcastle General Hospital, Newcastle upon Tyne, UK.
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511
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Abstract
Two-photon excitation fluorescence microscopy and backscattered-second harmonic generation microscopy permit the investigation of the subcellular events within living animals but numerous aspects of these experiments need to be optimized to overcome the traditional microscope geometry, motion and optical coupling to the subject. This report describes a stable system for supporting a living instrumented mouse or rabbit during endogenous reduced nicotinamide adenine dinucleotide and exogenous dye two-photon excitation fluorescence microscopy measurements, and backscattered-second harmonic generation microscopy measurements. The system was a modified inverted LSM510 microscope (Carl Zeiss, Inc., Thornwood, NY, U.S.A.) with a rotating periscope that converted the inverted scope to an upright format, with the objective located approximately, 15 cm from the centre of the microscope base, allowing easy placement of an instrumented animal. An Olympus 20x water immersion objective was optically coupled to the tissue, without a cover glass, via a saline bath or custom hydrated transparent gel. The instrumented animals were held on a specially designed holder that poised the animal under the objective as well as permitted different ventilation schemes to minimize motion. Using this approach, quality images were routinely collected in living animals from both the peripheral and body cavity organs. The remaining most significant issue for physiological studies using this approach is motion on the micrometre scale. Several strategies for motion compensation are described and discussed.
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Affiliation(s)
- Emily C Rothstein
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Department of Human Health Services, Bethesda, MD 20892, USA.
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512
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Abstract
In vivo microscopy is an exciting tool for neurological research because it can reveal how single cells respond to damage of the nervous system. This helps us to understand how diseases unfold and how therapies work. Here, we review the optical imaging techniques used to visualize the different parts of the nervous system, and how they have provided fresh insights into the aetiology and therapeutics of neurological diseases. We focus our discussion on five areas of neuropathology (trauma, degeneration, ischaemia, inflammation and seizures) in which in vivo microscopy has had the greatest impact. We discuss the challenging issues in the field, and argue that the convergence of new optical and non-optical methods will be necessary to overcome these challenges.
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Affiliation(s)
- Thomas Misgeld
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA.
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513
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Abstract
The brain is complex and dynamic. The spatial scales of interest to the neurobiologist range from individual synapses (approximately 1 microm) to neural circuits (centimeters); the timescales range from the flickering of channels (less than a millisecond) to long-term memory (years). Remarkably, fluorescence microscopy has the potential to revolutionize research on all of these spatial and temporal scales. Two-photon excitation (2PE) laser scanning microscopy allows high-resolution and high-sensitivity fluorescence microscopy in intact neural tissue, which is hostile to traditional forms of microscopy. Over the last 10 years, applications of 2PE, including microscopy and photostimulation, have contributed to our understanding of a broad array of neurobiological phenomena, including the dynamics of single channels in individual synapses and the functional organization of cortical maps. Here we review the principles of 2PE microscopy, highlight recent applications, discuss its limitations, and point to areas for future research and development.
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Affiliation(s)
- Karel Svoboda
- HHMI, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
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514
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Hutchinson EB, Stefanovic B, Koretsky AP, Silva AC. Spatial flow-volume dissociation of the cerebral microcirculatory response to mild hypercapnia. Neuroimage 2006; 32:520-30. [PMID: 16713717 DOI: 10.1016/j.neuroimage.2006.03.033] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2005] [Revised: 03/07/2006] [Accepted: 03/16/2006] [Indexed: 11/16/2022] Open
Abstract
The spatial and temporal response of the cerebral microcirculation to mild hypercapnia was investigated via two-photon laser-scanning microscopy. Cortical vessels, traversing the top 200 microm of somatosensory cortex, were visualized in alpha-chloralose-anesthetized Sprague-Dawley rats equipped with a cranial window. Intraluminal vessel diameters, transit times of fluorescent dextrans and red blood cells (RBC) velocities in individual capillaries were measured under normocapnic (PaCO2= 32.6 +/- 2.6 mm Hg) and slightly hypercapnic (PaCO2= 45 +/- 7 mm Hg) conditions. This gentle increase in PaCO2 was sufficient to produce robust and significant increases in both arterial and venous vessel diameters, concomitant to decreases in transit times of a bolus of dye from artery to venule (14%, P < 0.05) and from artery to vein (27%, P < 0.05). On the whole, capillaries exhibited a significant increase in diameter (16 +/- 33%, P < 0.001, n = 393) and a substantial increase in RBC velocities (75 +/- 114%, P < 0.001, n = 46) with hypercapnia. However, the response of the cerebral microvasculature to modest increases in PaCO2 was spatially heterogeneous. The maximal relative dilatation (range: 5-77%; mean +/- SD: 25 +/- 34%, P < 0.001, n = 271) occurred in the smallest capillaries (1.6 microm-4.0 microm resting diameter), while medium and larger capillaries (4.4 microm-6.8 microm resting diameter) showed no significant changes in diameter (P > 0.08, n = 122). In contrast, on average, RBC velocities increased less in the smaller capillaries (39 +/- 5%, P < 0.002, n = 22) than in the medium and larger capillaries (107 +/- 142%, P < 0.003, n = 24). Thus, the changes in capillary RBC velocities were spatially distinct from the observed volumetric changes and occurred to homogenize cerebral blood flow along capillaries of all diameters.
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Affiliation(s)
- Elizabeth B Hutchinson
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Building 10, Room B1D114, Bethesda, MD 20892-1065, USA
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515
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Kannurpatti SS, Biswal BB. Spatial extent of CBF response during whisker stimulation using trial averaged laser Doppler imaging. Brain Res 2006; 1089:135-42. [PMID: 16631137 DOI: 10.1016/j.brainres.2006.02.114] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Revised: 02/21/2006] [Accepted: 02/22/2006] [Indexed: 10/24/2022]
Abstract
The spatial pattern of activation in response to multiple whisker stimulation was studied using high-resolution laser Doppler (LD) imaging in urethane-anesthetized rats. LD flux change representing cerebral blood flow (CBF) responses were analyzed from a single trial or after averaging a number of similar trials. CBF change in a single trial was observed predominantly over pixels having low baseline flux values (microvessels), which included diffuse circular patterns of activation 400-800 microm in diameter similar to the histological dimensions of individual barrels established in the layer IV of the rat somatosensory cortex. The overall activation pattern varied considerably between each trial (only about 9-10% overlap); however, the diffuse circular pattern of activation was reproducible in every single trial within and across all rats. With trial averaging, no significant increase was observed in the outer boundary of activation, but the number of activated pixels increased within the diffuse circular patterns of activation. Emergence of further active pixels primarily within the diffuse circular regions of activity with trial averaging indicates distinct CBF responses in the septal and barrel regions, with a lesser LD signal to noise ratio in the barrel core.
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Affiliation(s)
- Sridhar S Kannurpatti
- Department of Radiology, UMDNJ-New Jersey Medical School, ADMC Bldg 5, Suite 575, 30 Bergen Street, Newark, NJ 07103, USA.
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516
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Yacoub E, Ugurbil K, Harel N. The spatial dependence of the poststimulus undershoot as revealed by high-resolution BOLD- and CBV-weighted fMRI. J Cereb Blood Flow Metab 2006; 26:634-44. [PMID: 16222242 DOI: 10.1038/sj.jcbfm.9600239] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The hemodynamic response to neural activity consists of changes in blood flow, blood volume and oxygen metabolism. Changes in the vascular state after sensory stimulation have different spatial and temporal characteristics in the brain. This has been shown using imaging techniques, such as BOLD functional magnetic resonance imaging (fMRI), which monitor vascular changes once the stimulus is turned on, and the eventual return to baseline levels, once the stimulus is turned off. The BOLD fMRI signal during sensory stimulation has been well characterized and modeled in terms of the spatial and temporal characteristics of the vascular response. However, the return of the signals to baseline levels after sensory stimulation is not as well characterized. During this period, a poststimulus undershoot in the BOLD signal is observed. This poststimulus undershoot has been modeled and investigated to characterize the physiological mechanisms (cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral oxygen consumption) associated with the response. However, the data in the literature, which lack any spatially dependent information, appear to be contradictory in terms of the mechanisms associated with this poststimulus response. With a high spatial resolution cat model at 9.4 T, we show that CBV changes in the tissue persist once the stimulus is turned off, while CBV changes in the surface vessels quickly return to baseline levels, despite a concurrent undershoot in the BOLD signal in both the tissue and surface vessel areas. In addition, the BOLD data alone indicate that different physiological mechanisms regulate the poststimulus response in the tissue versus the surface vessel regions.
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Affiliation(s)
- Essa Yacoub
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
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517
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Sun X, Shih AY, Johannssen HC, Erb H, Li P, Murphy TH. Two-photon imaging of glutathione levels in intact brain indicates enhanced redox buffering in developing neurons and cells at the cerebrospinal fluid and blood-brain interface. J Biol Chem 2006; 281:17420-17431. [PMID: 16624809 DOI: 10.1074/jbc.m601567200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glutathione is the major cellular thiol present in mammalian cells and is critical for maintenance of redox homeostasis. However, current assay systems for glutathione lack application to intact animal tissues. To map the levels of glutathione in intact brain with cellular resolution (acute tissue slices and live animals), we have used two-photon imaging of monochlorobimane fluorescence, a selective enzyme-mediated marker for reduced glutathione. Previously, in vitro experiments using purified components and cultured glial cells attributed cellular monochlorobimane fluorescence to a glutathione S-transferase-dependent reaction with GSH. Our results indicate that cells at the cerebrospinal fluid or blood-brain interface, such as lateral ventricle ependymal cells (2.73 +/- 0.56 mm; glutathione), meningeal cells (1.45 +/- 0.09 mm), and astroglia (0.91 +/- 0.08 mm), contain high levels of glutathione. In comparison, layer II cortical neurons contained 20% (0.21 +/- 0.02 mm) the glutathione content of nearby astrocytes. Neuronal glutathione labeling increased 250% by the addition of the cell-permeable glutathione precursor N-acetylcysteine indicating that the monochlorobimane level or glutathione S-transferase activity within neurons was not limiting. Regional mapping showed that glutathione was highest in cells lining the lateral ventricles, specifically ependymal cells and the subventricular zone, suggesting a possible function for glutathione in oxidant homeostasis of developing neuronal progenitors. Consistently, developing neurons in the subgranular zone of dentate gyrus contained 3-fold more glutathione than older neurons found in the neighboring granular layer. In conclusion, mapping of glutathione levels in intact brain demonstrates a unique role for enhanced redox potential in developing neurons and cells at the cerebrospinal fluid and blood-brain interface.
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Affiliation(s)
- Xiaojian Sun
- Departments of Psychiatry, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
| | - Andy Y Shih
- Departments of Psychiatry, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
| | - Helge C Johannssen
- Departments of Psychiatry, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
| | - Heidi Erb
- Departments of Psychiatry, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
| | - Ping Li
- Departments of Psychiatry, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
| | - Timothy H Murphy
- Departments of Psychiatry, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada; Departments of Physiology, Kinsmen Laboratory of Neurological Research and Brain Research Centre, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada.
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518
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Nguyen QT, Tsai PS, Kleinfeld D. MPScope: a versatile software suite for multiphoton microscopy. J Neurosci Methods 2006; 156:351-9. [PMID: 16621010 DOI: 10.1016/j.jneumeth.2006.03.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 02/22/2006] [Accepted: 03/01/2006] [Indexed: 11/17/2022]
Abstract
MPScope is a software suite to control and analyze data from custom-built multiphoton laser scanning fluorescence microscopes. The acquisition program MPScan acquires, displays and stores movies, linescans, image stacks or arbitrary regions from up to four imaging channels and up to two analog inputs, while plotting the intensity of regions of interest in real-time. Bidirectional linescans allow 256 x 256 pixel frames to be acquired at up to 10 fps with typical galvanometric scanners. A fast stack mode combines movie acquisition with continuous z-focus motion and adjustment of laser intensity for constant image brightness. Fast stacks can be automated by custom programs running in an integrated scripting environment, allowing a 1 mm(3) cortical volume to be sampled in 1 billion voxels in approximately 1 h. The analysis program MPView allows viewing of stored frames, projections, automatic detection of cells and plotting of their average intensity across frames, direct frame transfer to Matlab, AVI movie creation and file export to ImageJ. The combination of optimized code, multithreading and COM (Common Object Model) technologies enables MPScope to fully take advantage of custom-built two-photon microscopes and to simplify their realization.
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Affiliation(s)
- Quoc-Thang Nguyen
- Physics Department, University of California, San Diego, CA 92093-7697, USA.
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519
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Kang JJ, Toma I, Sipos A, McCulloch F, Peti-Peterdi J. Quantitative imaging of basic functions in renal (patho)physiology. Am J Physiol Renal Physiol 2006; 291:F495-502. [PMID: 16609147 DOI: 10.1152/ajprenal.00521.2005] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Multiphoton fluorescence microscopy offers the advantages of deep optical sectioning of living tissue with minimal phototoxicity and high optical resolution. More importantly, dynamic processes and multiple functions of an intact organ can be visualized in real time using noninvasive methods, and quantified. These studies aimed to extend existing methods of multiphoton fluorescence imaging to directly observe and quantify basic physiological parameters of the kidney including glomerular filtration rate (GFR) and permeability, blood flow, urinary concentration/dilution, renin content and release, as well as more integrated and complex functions like the tubuloglomerular feedback (TGF)-mediated oscillations in glomerular filtration and tubular flow. Streptozotocin-induced diabetes significantly increased single-nephron GFR (SNGFR) from 32.4 +/- 0.4 to 59.5 +/- 2.5 nl/min and glomerular permeability to a 70-kDa fluorophore approximately eightfold. The loop diuretic furosemide 2-fold diluted and increased approximately 10-fold the volume of distal tubular fluid, while also causing the release of 20% of juxtaglomerular renin content. Significantly higher speeds of individual red blood cells were measured in intraglomerular capillaries (16.7 +/- 0.4 mm/s) compared with peritubular vessels (4.7 +/- 0.2 mm/s). Regular periods of glomerular contraction-relaxation were observed, resulting in oscillations of filtration and tubular flow rate. Oscillations in proximal and distal tubular flow showed similar cycle times ( approximately 45 s) to glomerular filtration, with a delay of approximately 5-10 and 25-30 s, respectively. These innovative technologies provide the most complex, immediate, and dynamic portrayal of renal function, clearly depicting the components and mechanisms involved in normal physiology and pathophysiology.
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Affiliation(s)
- Jung Julie Kang
- Department of Physiology, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California 90033, USA
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520
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Ohno Y, Birn H, Christensen EI. In vivo confocal laser scanning microscopy and micropuncture in intact rat. Nephron Clin Pract 2006; 99:e17-25. [PMID: 15637463 DOI: 10.1159/000081794] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Accepted: 07/14/2004] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Intravital microscopy theoretically provides the optimal conditions for studying specific organ functions. However, the application of microscopy in intact organs in vivo has been limited so far due to technical difficulties. The purpose of this study was to establish a method of in vivo confocal laser scanning microscopy (CLSM) for the study of endocytosis in proximal tubules of intact kidney. METHODS The left kidney of rats placed on a modified microscope stage was exposed and stabilized in a thermostatically controlled cup. The stage was then attached to an upright confocal microscope. Surface proximal tubules were microinfused with fluorescent albumin or transferrin. Single or time-series images of microinfused proximal tubules were recorded in reflection and/or fluorescence mode. RESULTS The stability of the kidney and the resolution of images were sufficient to visualize intracellular vesicles. Albumin and transferrin were initially observed at the brush border, then later internalized by proximal tubules and accumulated in lysosomes over a time period of 15 min. Furthermore, fusion of vesicles was observed in time-lapse images. CONCLUSION These results show that in vivo CLSM in intact kidney may be an excellent method to evaluate proximal tubular endocytosis and ligand trafficking.
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Affiliation(s)
- Yoshio Ohno
- Department of Cell Biology, Institute of Anatomy, University of Aarhus, Aarhus, Denmark
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521
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Abstract
Multiphoton fluorescence microscopy is a powerful, important tool in biomedical research that offers low photon toxicity and higher spatial and temporal resolution than other in vivo imaging modalities. The capability to collect images hundreds of micrometers into biological tissues provides an invaluable tool for studying cellular and subcellular processes in the context of tissues and organs in living animals. Multiphoton microscopy is based upon two-photon excitation of fluorescence that occurs only in a sub-femtoliter volume at the focus; by scanning the focus through a sample, 2- and 3-dimensional images can be collected. The complex 3-dimensional organization of the kidney makes it especially appropriate for multiphoton microscopic analysis, which has been used to characterize numerous aspects of renal physiology and pathophysiology in living rats and mice. However, the ability to collect fluorescence images deep into biological tissues raises unique problems not encountered in other forms of optical microscopy, including issues of probe access, and tissue optics. Future improvements in multiphoton fluorescence microscopy will involve optimizing objectives for the unique characteristics of multiphoton fluorescence imaging, improving the speed at which images may be collected and extending the depth to which imaging may be conducted.
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Affiliation(s)
- Kenneth W Dunn
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Ind 46202, USA.
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522
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Zhang S, Boyd J, Delaney K, Murphy TH. Rapid reversible changes in dendritic spine structure in vivo gated by the degree of ischemia. J Neurosci 2006; 25:5333-8. [PMID: 15930381 PMCID: PMC6724996 DOI: 10.1523/jneurosci.1085-05.2005] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Current therapeutic windows for effective application of thrombolytic agents are within 3-6 h of stroke. Although treatment can improve outcome, it is unclear what happens to synaptic fine structure during this critical period in vivo. The relationship between microcirculation and dendritic spine structure was determined in mouse somatosensory neurons during stroke. Spines were, on average, 13 mum from a capillary and were supplied by approximately 100 red blood cells per second. Moderate ischemia (approximately 50% supply) did not significantly affect spines within 5 h; however, severe ischemia (<10% supply) caused a rapid loss of spine and dendrite structure within as little as 10 min. Surprisingly, if reperfusion occurred within 20-60 min, dendrite and spine structure was mostly restored. These data suggest that the basic dendritic wiring diagram remains mostly intact during moderate ischemia and that affected synapses could potentially contribute to functional recovery. With severe ischemia, markedly deformed dendritic structure can partially recover if reperfusion occurs early.
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Affiliation(s)
- Shengxiang Zhang
- Kinsmen Laboratory, Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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523
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Thompson JK, Peterson MR, Freeman RD. Separate spatial scales determine neural activity-dependent changes in tissue oxygen within central visual pathways. J Neurosci 2006; 25:9046-58. [PMID: 16192396 PMCID: PMC6725582 DOI: 10.1523/jneurosci.2127-05.2005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The relationship between oxygen levels and neural activity in the brain is fundamental to functional neuroimaging techniques. We have examined this relationship on a fine spatial scale in the lateral geniculate nucleus (LGN) and visual cortex of the cat using a microelectrode sensor that provides simultaneous colocalized measurements of oxygen partial pressure in tissue (tissue oxygen) and multiunit neural activity. In previous work with this sensor, we found that changes in tissue oxygen depend strongly on the location and spatial extent of neural activation. Specifically, focal neural activity near the microelectrode elicited decreases in tissue oxygen, whereas spatially extended activation, outside the field of view of our sensor, yielded mainly increases. In the current study, we report an expanded set of measurements to quantify the spatiotemporal relationship between neural responses and changes in tissue oxygen. For the purpose of data analysis, we develop a quantitative model that assumes that changes in tissue oxygen are composed of two response components (one positive and one negative) with magnitudes determined by neural activity on separate spatial scales. Our measurements from visual cortex and the LGN are consistent with this model and suggest that the positive response spreads over a distance of 1-2 mm, whereas the negative component is confined to a few hundred micrometers. These results are directly relevant to the mechanisms that generate functional brain imaging signals and place limits on their spatial properties.
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Affiliation(s)
- Jeffrey K Thompson
- School of Optometry, University of California, Berkeley, California 94720-2020, USA
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524
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Nishimura N, Schaffer CB, Friedman B, Tsai PS, Lyden PD, Kleinfeld D. Targeted insult to subsurface cortical blood vessels using ultrashort laser pulses: three models of stroke. Nat Methods 2006; 3:99-108. [PMID: 16432519 DOI: 10.1038/nmeth844] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Accepted: 12/05/2005] [Indexed: 12/24/2022]
Abstract
We present a method to produce vascular disruptions within rat brain parenchyma that targets single microvessels. We used two-photon microscopy to image vascular architecture, to select a vessel for injury and to measure blood-flow dynamics. We irradiated the vessel with high-fluence, ultrashort laser pulses and achieved three forms of vascular insult. (i) Vessel rupture was induced at the highest optical energies; this provides a model for hemorrhage. (ii) Extravasation of blood components was induced near the lowest energies and was accompanied by maintained flow in the target vessel. (iii) An intravascular clot evolved when an extravasated vessel was further irradiated. Such clots dramatically impaired blood flow in downstream vessels, in which speeds dropped to as low as approximately 10% of baseline values. This demonstrates that a single blockage to a microvessel can lead to local cortical ischemia. Lastly, we show that hemodilution leads to a restoration of flow in secondary downstream vessels.
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Affiliation(s)
- Nozomi Nishimura
- Department of Physics, University of California at San Diego, La Jolla, California 92093, USA
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525
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Abstract
With few exceptions biological tissues strongly scatter light, making high-resolution deep imaging impossible for traditional-including confocal-fluorescence microscopy. Nonlinear optical microscopy, in particular two photon-excited fluorescence microscopy, has overcome this limitation, providing large depth penetration mainly because even multiply scattered signal photons can be assigned to their origin as the result of localized nonlinear signal generation. Two-photon microscopy thus allows cellular imaging several hundred microns deep in various organs of living animals. Here we review fundamental concepts of nonlinear microscopy and discuss conditions relevant for achieving large imaging depths in intact tissue.
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Affiliation(s)
- Fritjof Helmchen
- Department of Neurophysiology, Brain Research Institute, University of Zurich, CH-8057 Zurich, Switzerland.
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526
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Schaffer CB, Friedman B, Nishimura N, Schroeder LF, Tsai PS, Ebner FF, Lyden PD, Kleinfeld D. Two-photon imaging of cortical surface microvessels reveals a robust redistribution in blood flow after vascular occlusion. PLoS Biol 2006; 4:e22. [PMID: 16379497 PMCID: PMC1324794 DOI: 10.1371/journal.pbio.0040022] [Citation(s) in RCA: 264] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 11/11/2005] [Indexed: 01/23/2023] Open
Abstract
A highly interconnected network of arterioles overlies mammalian cortex to route blood to the cortical mantle. Here we test if this angioarchitecture can ensure that the supply of blood is redistributed after vascular occlusion. We use rodent parietal cortex as a model system and image the flow of red blood cells in individual microvessels. Changes in flow are quantified in response to photothrombotic occlusions to individual pial arterioles as well as to physical occlusions of the middle cerebral artery (MCA), the primary source of blood to this network. We observe that perfusion is rapidly reestablished at the first branch downstream from a photothrombotic occlusion through a reversal in flow in one vessel. More distal downstream arterioles also show reversals in flow. Further, occlusion of the MCA leads to reversals in flow through approximately half of the downstream but distant arterioles. Thus the cortical arteriolar network supports collateral flow that may mitigate the effects of vessel obstruction, as may occur secondary to neurovascular pathology. The authors quantify changes in blood flow in the pial arteriolar network of rodent cortex following targeted occlusions to individual vessels.
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Affiliation(s)
- Chris B Schaffer
- 1Department of Physics, University of California San Diego, La Jolla, California, United States of America
- 2Center for Theoretical Biological Physics, University of California San Diego, La Jolla, California, United States of America
| | - Beth Friedman
- 3Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
- 4Department of Neurology, Veterans Affairs Medical Center, San Diego, California, United States of America
| | - Nozomi Nishimura
- 1Department of Physics, University of California San Diego, La Jolla, California, United States of America
- 2Center for Theoretical Biological Physics, University of California San Diego, La Jolla, California, United States of America
| | - Lee F Schroeder
- 5Graduate Program in Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Philbert S Tsai
- 1Department of Physics, University of California San Diego, La Jolla, California, United States of America
- 2Center for Theoretical Biological Physics, University of California San Diego, La Jolla, California, United States of America
| | - Ford F Ebner
- 6Department of Psychology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Patrick D Lyden
- 3Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
- 4Department of Neurology, Veterans Affairs Medical Center, San Diego, California, United States of America
- 5Graduate Program in Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - David Kleinfeld
- 1Department of Physics, University of California San Diego, La Jolla, California, United States of America
- 2Center for Theoretical Biological Physics, University of California San Diego, La Jolla, California, United States of America
- 5Graduate Program in Neurosciences, University of California San Diego, La Jolla, California, United States of America
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527
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Demchenko IT, Luchakov YI, Moskvin AN, Gutsaeva DR, Allen BW, Thalmann ED, Piantadosi CA. Cerebral blood flow and brain oxygenation in rats breathing oxygen under pressure. J Cereb Blood Flow Metab 2005; 25:1288-300. [PMID: 15789033 DOI: 10.1038/sj.jcbfm.9600110] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hyperbaric oxygen (HBO(2)) increases oxygen tension (PO(2)) in blood but reduces blood flow by means of O(2)-induced vasoconstriction. Here we report the first quantitative evaluation of these opposing effects on tissue PO(2) in brain, using anesthetized rats exposed to HBO(2) at 2 to 6 atmospheres absolute (ATA). We assessed the contribution of regional cerebral blood flow (rCBF) to brain PO(2) as inspired PO(2) (PiO(2)) exceeds 1 ATA. We measured rCBF and local PO(2) simultaneously in striatum using collocated platinum electrodes. Cerebral blood flow was computed from H(2) clearance curves in vivo and PO(2) from electrodes calibrated in vitro, before and after insertion. Arterial PCO(2) was controlled, and body temperature, blood pressure, and EEG were monitored. Scatter plots of rCBF versus PO(2) were nonlinear (R(2)=0.75) for rats breathing room air but nearly linear (R(2)=0.88-0.91) for O(2) at 2 to 6 ATA. The contribution of rCBF to brain PO(2) was estimated at constant inspired PO(2), by increasing rCBF with acetazolamide (AZA) or decreasing it with N-nitro-L-arginine methyl ester (L-NAME). At basal rCBF (78 mL/100 g min), local PO(2) increased 7- to 33-fold at 2 to 6 ATA, compared with room air. A doubling of rCBF increased striatal PO(2) not quite two-fold in rats breathing room air but 13- to 64-fold in those breathing HBO(2) at 2 to 6 ATA. These findings support our hypothesis that HBO(2) increases PO(2) in brain in direct proportion to rCBF.
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Affiliation(s)
- Ivan T Demchenko
- Center for Hyperbaric Medicine and Environmental Physiology, Duke University, Durham, North Carolina 27710, USA
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528
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Singer RH, Lawrence DS, Ovryn B, Condeelis J. Imaging of gene expression in living cells and tissues. JOURNAL OF BIOMEDICAL OPTICS 2005; 10:051406. [PMID: 16292943 DOI: 10.1117/1.2103032] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
It is possible to observe gene expression within single cells using a tetracycline inducible promoter for activation. Transcription can be observed by using a fluorescent fusion protein to bind nascent RNA. Ultimately, it is desirable to activate a reporter gene within a single cell with only photons. This is achieved by preparing a chemically altered transcription factor that is functionally unable to activate a reporter gene until it is exposed to photon excitation. We apply two-photon imaging to visualize tumor cells expressing a transgene and ultimately this approach will provide the means to activate a specific gene within a single cell within any tissue to ultimately observe its functional significance in situ.
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Affiliation(s)
- Robert H Singer
- Albert Einstein College of Medicine, Department of Anatomy and Structural Biology and Biochemistry, Biophotonics Center, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
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529
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Zheng Y, Johnston D, Berwick J, Chen D, Billings S, Mayhew J. A three-compartment model of the hemodynamic response and oxygen delivery to brain. Neuroimage 2005; 28:925-39. [PMID: 16061400 DOI: 10.1016/j.neuroimage.2005.06.042] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Revised: 06/22/2005] [Accepted: 06/30/2005] [Indexed: 11/29/2022] Open
Abstract
We describe a mathematical model linking changes in cerebral blood flow, blood volume and the blood oxygenation state in response to stimulation. The model has three compartments to take into account the fact that the cerebral blood flow and volume as measured concurrently using laser Doppler flowmetry and optical imaging spectroscopy have contributions from the arterial, capillary as well as the venous compartments of the vasculature. It is an extension to previous one-compartment hemodynamic models which assume that the measured blood volume changes are from the venous compartment only. An important assumption of the model is that the tissue oxygen concentration is a time varying state variable of the system and is driven by the changes in metabolic demand resulting from changes in neural activity. The model takes into account the pre-capillary oxygen diffusion by flexibly allowing the saturation of the arterial compartment to be less than unity. Simulations are used to explore the sensitivity of the model and to optimise the parameters for experimental data. We conclude that the three-compartment model was better than the one-compartment model at capturing the hemodynamics of the response to changes in neural activation following stimulation.
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Affiliation(s)
- Ying Zheng
- Department of Psychology, University of Sheffield, UK.
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530
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Kiviniemi V, Ruohonen J, Tervonen O. Separation of physiological very low frequency fluctuation from aliasing by switched sampling interval fMRI scans. Magn Reson Imaging 2005; 23:41-6. [PMID: 15733787 DOI: 10.1016/j.mri.2004.09.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 09/22/2004] [Indexed: 11/29/2022]
Abstract
Anesthetized children have dominant blood-oxygen-level-dependent (BOLD) signal sources presenting high-power fluctuations at very low frequencies (VLF <0.05 Hz). Aliasing of frequencies higher than critically sampled has been regarded as one probable origin of the VLF fluctuations. Aliased signal frequencies change when the sampling rate of the data is altered. In this study, the aliasing of VLF BOLD signal fluctuation was analysed by switching the repetition time (TR) of magnetic resonance (MR) images. Eleven anesthetized children were imaged at 1.5 T using TRs of 500 and 1200 ms. The BOLD signal sources were separated with independent component analysis (ICA). Occipital cortex signal sources had nonaliased VLF fluctuation ( approximately 0.03 Hz) in 9 of 11 subjects. Arterial signal sources failed to present stable power peaks at frequencies lower than 0.42 Hz presumably due to aliasing. Cerebrospinal fluid (CSF)-related signal sources showed nonaliased VLF in four subjects. In conclusion, the VLF BOLD signal fluctuation in the occipital cortex is a true physiological fluctuation, not a result of signal aliasing.
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Affiliation(s)
- Vesa Kiviniemi
- Department of Diagnostic Radiology, University of Oulu, OYS 90029, Finland.
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531
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Abstract
Two-photon excitation fluorescence imaging provides thin optical sections from deep within thick, scattering specimens by way of restricting fluorophore excitation (and thus emission) to the focal plane of the microscope. Spatial confinement of two-photon excitation gives rise to several advantages over single-photon confocal microscopy. First, penetration depth of the excitation beam is increased. Second, because out-of-focus fluorescence is never generated, no pinhole is necessary in the detection path of the microscope, resulting in increased fluorescence collection efficiency. Third, two-photon excitation markedly reduces overall photobleaching and photodamage, resulting in extended viability of biological specimens during long-term imaging. Finally, localized excitation can be used for photolysis of caged compounds in femtoliter volumes and for diffusion measurements by two-photon fluorescence photobleaching recovery. This review aims to provide an overview of the use of two-photon excitation microscopy. Selected applications of this technique will illustrate its excellent suitability to assess cellular and subcellular events in intact, strongly scattering tissue. In particular, its capability to resolve differences in calcium dynamics between individual cardiomyocytes deep within intact, buffer-perfused hearts is demonstrated. Potential applications of two-photon laser scanning microscopy as applied to integrative cardiac physiology are pointed out.
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Affiliation(s)
- Michael Rubart
- Herman B Wells Center for Pediatric Research and Krannert Institute of Cardiology, Indiana University School of Medicine, 1044 W Walnut St, Rm W359, Indianapolis, IN 46202-5225, USA.
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532
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Abstract
The cellular components of the brain are neurons, glia and vascular cells. These three entities form a metabolic network to sustain brain activity. Interactions among these cell types have been studied extensively in vitro, where the cells are easily accessible to physiological and pharmacological manipulations. With the advent of optical tools, it has become possible to investigate the cerebral metabolic network in vitro at the cellular and subcellular levels. However, the metabolic and homeostatic nature of neuronal-glial-vascular interactions must eventually be examined in vivo, and multi-photon imaging now provides a means to monitor neurovascular units in living experimental animals.
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Affiliation(s)
- Hajime Hirase
- Neuronal Circuit Mechanisms Research Group, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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533
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Abstract
Nonlinear microscopy, a general term that embraces any microscopy technique based on nonlinear optics, is further establishing itself as an important tool in neurobiology. Recent advances in labels, labeling techniques, and the use of native or genetically encoded contrast agents have bolstered the capacity of nonlinear microscopes to image the structure and function of not just single cells but of entire networks of cells. Along with novel strategies to image over exceptionally long durations and with increased depth penetration in living brains, these advances are opening new opportunities in neurobiology that were previously unavailable.
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Affiliation(s)
- Jerome Mertz
- Boston University, Department of Biomedical Engineering, 44 Cummington Street, Boston, Massachusetts 02215, USA.
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534
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Vanzetta I, Hildesheim R, Grinvald A. Compartment-resolved imaging of activity-dependent dynamics of cortical blood volume and oximetry. J Neurosci 2005; 25:2233-44. [PMID: 15745949 PMCID: PMC6726087 DOI: 10.1523/jneurosci.3032-04.2005] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2004] [Revised: 01/07/2005] [Accepted: 01/08/2005] [Indexed: 11/21/2022] Open
Abstract
Optical imaging, positron emission tomography, and functional magnetic resonance imaging (fMRI) all rely on vascular responses to image neuronal activity. Although these imaging techniques are used successfully for functional brain mapping, the detailed spatiotemporal dynamics of hemodynamic events in the various microvascular compartments have remained unknown. Here we used high-resolution optical imaging in area 18 of anesthetized cats to selectively explore sensory-evoked cerebral blood-volume (CBV) changes in the various cortical microvascular compartments. To avoid the confounding effects of hematocrit and oximetry changes, we developed and used a new fluorescent blood plasma tracer and combined these measurements with optical imaging of intrinsic signals at a near-isosbestic wavelength for hemoglobin (565 nm). The vascular response began at the arteriolar level, rapidly spreading toward capillaries and venules. Larger veins lagged behind. Capillaries exhibited clear blood-volume changes. Arterioles and arteries had the largest response, whereas the venous response was smallest. Information about compartment-specific oxygen tension dynamics was obtained in imaging sessions using 605 nm illumination, a wavelength known to reflect primarily oximetric changes, thus being more directly related to electrical activity than CBV changes. Those images were radically different: the response began at the parenchyma level, followed only later by the other microvascular compartments. These results have implications for the modeling of fMRI responses (e.g., the balloon model). Furthermore, functional maps obtained by imaging the capillary CBV response were similar but not identical to those obtained using the early oximetric signal, suggesting the presence of different regulatory mechanisms underlying these two hemodynamic processes.
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Affiliation(s)
- Ivo Vanzetta
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel.
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535
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Abstract
Neurovascular and neurometabolic coupling help the brain to maintain an appropriate energy flow to the neural tissue under conditions of increased neuronal activity. Both coupling phenomena provide us, in addition, with two macroscopically measurable parameters, blood flow and intermediate metabolite fluxes, that are used to dynamically image the functioning brain. The main energy substrate for the brain is glucose, which is metabolized by glycolysis and oxidative breakdown in both astrocytes and neurons. Neuronal activation triggers increased glucose consumption and glucose demand, with new glucose being brought in by stimulated blood flow and glucose transport over the blood-brain barrier. Glucose is shuttled over the barrier by the GLUT-1 transporter, which, like all transporter proteins, has a ceiling above which no further stimulation of the transport is possible. Blood-brain barrier glucose transport is generally accepted as a nonrate-limiting step but to prevent it from becoming rate-limiting under conditions of neuronal activation, it might be necessary for the transport parameters to be adapted to the increased glucose demand. It is proposed that the blood-brain barrier glucose transport parameters are dynamically adapted to the increased glucose needs of the neural tissue after activation according to a neurobarrier coupling scheme. This review presents neurobarrier coupling within the current knowledge on neurovascular and neurometabolic coupling, and considers arguments and evidence in support of this hypothesis.
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Affiliation(s)
- Luc Leybaert
- Department of Physiology and Pathophysiology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
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536
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Woolsey TA. Barrels XVII–proceedings. Somatosens Mot Res 2005. [DOI: 10.1080/00319100500083641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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537
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538
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Wang H, Hitron IM, Iadecola C, Pickel VM. Synaptic and vascular associations of neurons containing cyclooxygenase-2 and nitric oxide synthase in rat somatosensory cortex. ACTA ACUST UNITED AC 2004; 15:1250-60. [PMID: 15616132 DOI: 10.1093/cercor/bhi008] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Cyclooxygenase-2 (COX-2) is a rate-limiting enzyme for prostanoid synthesis that is present in cortical pyramidal neurons and highly implicated in control of cerebral blood flow during neural activity. We examined the electron microscopic localization of COX-2 and neuronal nitric oxide synthase (nNOS), a functionally related enzyme, in the somatosensory cortex of rat brain to determine the relevant functional sites. COX-2 immunoreactivity was detected in significantly more somatodendritic than axonal profiles, while nNOS was more often seen in axon terminals. The dendritic COX-2 was localized to endomembranes near synaptic inputs from axon terminals, some of which contained nNOS. Conversely, COX-2 terminals formed asymmetric, excitatory-type synapses with dendrites containing nNOS. The dendritic and axonal profiles containing COX-2 as well as those containing nNOS were minimally separated from penetrating arterioles and capillaries by filamentous glial processes. The perivascular COX-2 labeled terminals were among those that also formed axo-dendritic synapses, suggesting that the release of prostanoids and/or excitatory transmitters from a single terminal may simultaneously affect neuronal activity and cerebral blood flow. Thus, COX-2 has a compartmental distribution in somatosensory cortical neurons consistent with the local neuronal synthesis of prostanoids that are involved in neurovascular coupling and whose actions are modulated by nitric oxide.
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Affiliation(s)
- Hong Wang
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021, USA
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539
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Rothstein EC, Carroll S, Combs CA, Jobsis PD, Balaban RS. Skeletal muscle NAD(P)H two-photon fluorescence microscopy in vivo: topology and optical inner filters. Biophys J 2004; 88:2165-76. [PMID: 15596503 PMCID: PMC1305268 DOI: 10.1529/biophysj.104.053165] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two-photon excitation fluorescence microscopy (TPEFM) permits the investigation of the topology of intercellular events within living animals. TPEFM was used to monitor the distribution of mitochondrial reduced nicotinamide adenine dinucleotide (NAD(P)H) in murine skeletal muscle in vivo. NAD(P)H fluorescence emission was monitored ( approximately 460 nm) using 710-720 nm excitation. High-resolution TPEFM images were collected up to a depth of 150 microm from the surface of the tibialis anterior muscle. The NAD(P)H fluorescence images revealed subcellular structures consistent with subsarcolemmal, perivascular, intersarcomeric, and paranuclear mitochondria. In vivo fiber typing between IIB and IIA/D fibers was possible using the distribution and content of mitochondria from the NAD(P)H fluorescence signal. The intersarcomeric mitochondria concentrated at the Z-line in the IIB fiber types resulting in a periodic pattern with a spacing of one sarcomere (2.34 +/- 0.17 microm). The primary inner filter effects were nearly equivalent to water, however, the secondary inner filter effects were highly significant and dynamically affected the observed emission frequency and amplitude of the NAD(P)H fluorescence signal. These data demonstrate the feasibility, and highlight the complexity, of using NAD(P)H TPEFM in skeletal muscle to characterize the topology and metabolic function of mitochondria within the living mouse.
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Affiliation(s)
- Emily C Rothstein
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Department of Human Health Services, Bldg. 10, Rm. B1D416, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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540
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Kong Y, Zheng Y, Johnston D, Martindale J, Jones M, Billings S, Mayhew J. A model of the dynamic relationship between blood flow and volume changes during brain activation. J Cereb Blood Flow Metab 2004; 24:1382-92. [PMID: 15625412 DOI: 10.1097/01.wcb.0000141500.74439.53] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The temporal relationship between changes in cerebral blood flow (CBF) and cerebral blood volume (CBV) is important in the biophysical modeling and interpretation of the hemodynamic response to activation, particularly in the context of magnetic resonance imaging and the blood oxygen level-dependent signal. measured the steady state relationship between changes in CBV and CBF after hypercapnic challenge. The relationship CBV is proportional to CBFphi has been used extensively in the literature. Two similar models, the Balloon and the Windkessel , have been proposed to describe the temporal dynamics of changes in CBV with respect to changes in CBF. In this study, a dynamic model extending the Windkessel model by incorporating delayed compliance is presented. The extended model is better able to capture the dynamics of CBV changes after changes in CBF, particularly in the return-to-baseline stages of the response.
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Affiliation(s)
- Yazhuo Kong
- Department of Automatic Control and Systems Engineering, University of Sheffield, Sheffield, UK
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541
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de Zwart JA, Silva AC, van Gelderen P, Kellman P, Fukunaga M, Chu R, Koretsky AP, Frank JA, Duyn JH. Temporal dynamics of the BOLD fMRI impulse response. Neuroimage 2004; 24:667-77. [PMID: 15652302 DOI: 10.1016/j.neuroimage.2004.09.013] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Revised: 09/07/2004] [Accepted: 09/08/2004] [Indexed: 11/16/2022] Open
Abstract
Using computer simulations and high-resolution fMRI experiments in humans (n=6) and rats (n=8), we investigated to what extent BOLD fMRI temporal resolution is limited by dispersion in the venous vasculature. For this purpose, time-to-peak (TTP) and full-width at half-maximum (FWHM) of the BOLD impulse response (IR) function were determined. In fMRI experiments, a binary m-sequence probe method was used to obtain high-sensitivity model-free single-pixel estimates of IR. Simulations of postcapillary flow suggested that flow-related dispersion leads to a TTP and FWHM increase, which can amount to several seconds in larger pial veins. fMRI experiments showed substantial spatial variation in IR timing within human visual cortex, together with a correlation between TTP and FWHM. Averaged across the activated regions and across subjects, TTP and FWHM were 4.51+/-0.52 and 4.04+/-0.42 s, respectively. In regions of interest (ROI) weighted toward the larger venous structures, TTP and FWHM increased to 5.07+/-0.64 and 4.32+/-0.48 s, respectively. In rat somatosensory cortex, TTP and FWHM were substantially shorter than in humans (2.73+/-0.60 and 2.28+/-0.63 s, respectively). These results are consistent with a substantial macrovascular dispersive contribution to BOLD IR in humans, and furthermore suggest that neurovascular coupling is a relatively rapid process, with a resolution below 2.3 s FWHM.
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Affiliation(s)
- Jacco A de Zwart
- Laboratory of Functional and Molecular Imaging, NINDS, National Institutes of Health, Bethesda, MD 20892-1065, USA.
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542
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Hirase H, Creso J, Buzsáki G. Capillary level imaging of local cerebral blood flow in bicuculline-induced epileptic foci. Neuroscience 2004; 128:209-16. [PMID: 15450368 DOI: 10.1016/j.neuroscience.2004.07.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2004] [Indexed: 11/21/2022]
Abstract
Local hemodynamics of the cerebral cortex is the basis of modern functional imaging techniques, such as fMRIand PET. Despite the importance of local regulation of the blood flow, capillary level quantification of cerebral blood flow has been limited by the spatial resolution of functional imaging techniques and the depth penetration of conventional optical microscopy. Two-photon laser scanning microscopic imaging technique has the necessary spatial resolution and can image capillaries in the depth of the cortex. We have loaded the serum with fluorescein isothiocyanate dextran and quantified the flow of red blood cells (RBCs) in capillaries in layers 2/3 of the mouse somatosensory cortex in vivo. Basal capillary flux was quantified as approximately 28.9+/-13.6 RBCs/s (n=50, mean+/-S.D.) under ketamine-xylazine anesthesia and 26.7+/-16.0 RBCs/s (n=31) under urethane anesthesia. Focal interictal (epileptiform) activity was induced by local infusion of bicuculline methochloride in the cortex. We have observed that capillary blood flow increased as the cortical local field events developed into epileptiform in the vicinity of GABA receptor blockade (<300 microm from the administration site). Local blood flow in the interictal focus increased significantly (42.5+/-18.5RBCs/s, n=52) relative to the control conditions or to blood flow measured in capillaries at distant (>1mm from the focus) sites from the epileptic focus (27.8+/-12.9 RBCs/s, n=30). These results show that hyper-synchronized neural activity is associated with increased capillary perfusion in a localized cortical area. This volume is significantly smaller than the currently available resolution of the fMRI signal.
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Affiliation(s)
- H Hirase
- Center for Molecular and Behavioral Neuroscience Rutgers, The State University of New Jersey, 197 University Avenue, Newark, NJ 07102, USA.
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543
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Mehta AD, Jung JC, Flusberg BA, Schnitzer MJ. Fiber optic in vivo imaging in the mammalian nervous system. Curr Opin Neurobiol 2004; 14:617-28. [PMID: 15464896 PMCID: PMC2826357 DOI: 10.1016/j.conb.2004.08.017] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The compact size, mechanical flexibility, and growing functionality of optical fiber and fiber optic devices are enabling several new modalities for imaging the mammalian nervous system in vivo. Fluorescence microendoscopy is a minimally invasive fiber modality that provides cellular resolution in deep brain areas. Diffuse optical tomography is a non-invasive modality that uses assemblies of fiber optic emitters and detectors on the cranium for volumetric imaging of brain activation. Optical coherence tomography is a sensitive interferometric imaging technique that can be implemented in a variety of fiber based formats and that might allow intrinsic optical detection of brain activity at a high resolution. Miniaturized fiber optic microscopy permits cellular level imaging in the brains of behaving animals. Together, these modalities will enable new uses of imaging in the intact nervous system for both research and clinical applications.
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Affiliation(s)
- Amit D Mehta
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Juergen C Jung
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
- Department of Pharmacology, Oxford University, Oxford, OX1 3QT, United Kingdom
| | | | - Mark J Schnitzer
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
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544
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Feierabend M, Rückel M, Denk W. Coherence-gated wave-front sensing in strongly scattering samples. OPTICS LETTERS 2004; 29:2255-7. [PMID: 15524372 DOI: 10.1364/ol.29.002255] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We show that, by coherence-gate rejection of out-of-focus light, wave-front distortions can be measured in the presence of a scattering background that is dominant by several orders of magnitude. Applications are expected for multiphoton and confocal laser-scanning microscopy.
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Affiliation(s)
- Marcus Feierabend
- Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
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545
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Navarro FA, So PTC, Nirmalan R, Kropf N, Sakaguchi F, Park CS, Lee HB, Orgill DP. Two-photon confocal microscopy: a nondestructive method for studying wound healing. Plast Reconstr Surg 2004; 114:121-8. [PMID: 15220579 DOI: 10.1097/01.prs.0000128374.20913.4b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Two-photon confocal microscopy is a new technology useful in nondestructive analysis of tissue. The pattern generated from laser-excited autofluorescence and second harmonic signals can be analyzed to construct a three-dimensional, microanatomical, structural image. The healing of full-thickness guinea pig skin wounds was studied over a period of 28 days using two-photon confocal microscopy. Three-dimensional data were rendered from two-dimensional images and compared with conventional, en face, histologic sections. Two-photon confocal microscopy images show resolution of muscle, fascia fibers, collagen fibers, inflammatory cells, blood vessels, and hair. Although these images do not currently have the resolution of standard histology, the ability to noninvasively acquire three-dimensional images of skin promises to be an important tool in wound-healing studies.
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Affiliation(s)
- Fernando A Navarro
- Division of Plastic Surgery, Brigham and Women's Hospital, Boston, MA 02115, USA
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546
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Jung JC, Mehta AD, Aksay E, Stepnoski R, Schnitzer MJ. In vivo mammalian brain imaging using one- and two-photon fluorescence microendoscopy. J Neurophysiol 2004; 92:3121-33. [PMID: 15128753 PMCID: PMC2826362 DOI: 10.1152/jn.00234.2004] [Citation(s) in RCA: 228] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
One of the major limitations in the current set of techniques available to neuroscientists is a dearth of methods for imaging individual cells deep within the brains of live animals. To overcome this limitation, we developed two forms of minimally invasive fluorescence microendoscopy and tested their abilities to image cells in vivo. Both one- and two-photon fluorescence microendoscopy are based on compound gradient refractive index (GRIN) lenses that are 350-1,000 microm in diameter and provide micron-scale resolution. One-photon microendoscopy allows full-frame images to be viewed by eye or with a camera, and is well suited to fast frame-rate imaging. Two-photon microendoscopy is a laser-scanning modality that provides optical sectioning deep within tissue. Using in vivo microendoscopy we acquired video-rate movies of thalamic and CA1 hippocampal red blood cell dynamics and still-frame images of CA1 neurons and dendrites in anesthetized rats and mice. Microendoscopy will help meet the growing demand for in vivo cellular imaging created by the rapid emergence of new synthetic and genetically encoded fluorophores that can be used to label specific brain areas or cell classes.
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Affiliation(s)
- Juergen C Jung
- Department of Biological Sciences, Stanford University, Stanford, CA 94305-5435, USA
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547
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Hirase H, Creso J, Singleton M, Barthó P, Buzsáki G. Two-photon imaging of brain pericytes in vivo using dextran-conjugated dyes. Glia 2004; 46:95-100. [PMID: 14999817 DOI: 10.1002/glia.10295] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pericytes in the central nervous system (CNS) are hypothesized to be involved in important circulatory functions, including local blood flow regulation, angiogenesis, immune reaction, and regulation of blood-brain barrier. Despite these putative functions, functional correlates of pericytes in vivo are scarce. We have labeled CNS pericytes using the dextran-conjugated fluorescent calcium indicator Calcium Green I and imaged them in somatosensory cortex of the mouse in vivo. Intracellular calcium concentration in pericytes showed spontaneous surges lasting for several seconds. Furthermore, population bursts of neuronal activity were associated with increased Ca(2+) signal in a portion of the pericytes. Selective in vivo labeling of pericytes with functional markers may help reveal their physiological function in neuronal activity-associated regulation of local cerebral blood flow.
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Affiliation(s)
- Hajime Hirase
- Center for Molecular and Behavioral Neuroscience, Rutgers, State University of New Jersey, Newark, New Jersey 07102, USA
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548
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Roberts RL, Lin PC. Structural and Functional Optical Imaging of Angiogenesis in Animal Models. Methods Enzymol 2004; 386:105-22. [PMID: 15120248 DOI: 10.1016/s0076-6879(04)86004-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
MESH Headings
- Animals
- Arthritis/pathology
- Blood Flow Velocity/physiology
- Blood Vessels/pathology
- Blood Vessels/physiopathology
- Capillary Permeability/physiology
- Cell Line, Tumor
- Corneal Neovascularization/pathology
- Diagnostic Imaging/methods
- Dilatation, Pathologic/pathology
- Erythrocytes/chemistry
- Female
- Fluorescent Dyes/analysis
- Green Fluorescent Proteins
- Hypoxia/physiopathology
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Mammary Neoplasms, Experimental/pathology
- Mammary Neoplasms, Experimental/physiopathology
- Mice
- Mice, Transgenic
- Microscopy/methods
- Microscopy, Confocal
- Microscopy, Fluorescence, Multiphoton
- Models, Animal
- Neoplasms/blood supply
- Neoplasms/pathology
- Neoplasms/therapy
- Neovascularization, Pathologic/pathology
- Neovascularization, Pathologic/physiopathology
- Rats
- Receptor, TIE-1/genetics
- Receptor, TIE-1/metabolism
- Receptor, TIE-2/genetics
- Receptor, TIE-2/metabolism
- Receptors, Vascular Endothelial Growth Factor/genetics
- Receptors, Vascular Endothelial Growth Factor/metabolism
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Affiliation(s)
- Richard L Roberts
- Department of Pathology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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549
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Levene MJ, Dombeck DA, Kasischke KA, Molloy RP, Webb WW. In vivo multiphoton microscopy of deep brain tissue. J Neurophysiol 2003; 91:1908-12. [PMID: 14668300 DOI: 10.1152/jn.01007.2003] [Citation(s) in RCA: 368] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although fluorescence microscopy has proven to be one of the most powerful tools in biology, its application to the intact animal has been limited to imaging several hundred micrometers below the surface. The rest of the animal has eluded investigation at the microscopic level without excising tissue or performing extensive surgery. However, the ability to image with subcellular resolution in the intact animal enables a contextual setting that may be critical for understanding proper function. Clinical applications such as disease diagnosis and optical biopsy may benefit from minimally invasive in vivo approaches. Gradient index (GRIN) lenses with needle-like dimensions can transfer high-quality images many centimeters from the object plane. Here, we show that multiphoton microscopy through GRIN lenses enables minimally invasive, subcellular resolution several millimeters in the anesthetized, intact animal, and we present in vivo images of cortical layer V and hippocampus in the anesthetized Thy1-YFP line H mouse. Microangiographies from deep capillaries and blood vessels containing fluorescein-dextran and quantum dot-labeled serum in wild-type mouse brain are also demonstrated.
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Affiliation(s)
- Michael J Levene
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
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550
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Zipfel WR, Williams RM, Webb WW. Nonlinear magic: multiphoton microscopy in the biosciences. Nat Biotechnol 2003; 21:1369-77. [PMID: 14595365 DOI: 10.1038/nbt899] [Citation(s) in RCA: 2206] [Impact Index Per Article: 105.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Multiphoton microscopy (MPM) has found a niche in the world of biological imaging as the best noninvasive means of fluorescence microscopy in tissue explants and living animals. Coupled with transgenic mouse models of disease and 'smart' genetically encoded fluorescent indicators, its use is now increasing exponentially. Properly applied, it is capable of measuring calcium transients 500 microm deep in a mouse brain, or quantifying blood flow by imaging shadows of blood cells as they race through capillaries. With the multitude of possibilities afforded by variations of nonlinear optics and localized photochemistry, it is possible to image collagen fibrils directly within tissue through nonlinear scattering, or release caged compounds in sub-femtoliter volumes.
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MESH Headings
- Biological Science Disciplines/instrumentation
- Biological Science Disciplines/methods
- Biological Science Disciplines/trends
- Equipment Design
- Image Enhancement/instrumentation
- Image Enhancement/methods
- Imaging, Three-Dimensional/instrumentation
- Imaging, Three-Dimensional/methods
- Imaging, Three-Dimensional/trends
- Microscopy, Confocal/instrumentation
- Microscopy, Confocal/methods
- Microscopy, Confocal/trends
- Microscopy, Fluorescence, Multiphoton/instrumentation
- Microscopy, Fluorescence, Multiphoton/methods
- Microscopy, Fluorescence, Multiphoton/trends
- Nonlinear Dynamics
- Transducers
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Affiliation(s)
- Warren R Zipfel
- School of Applied and Engineering Physics, 212 Clark Hall, Cornell University, Ithaca, New York 14853, USA
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