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Linsenmeier RA, Dmitriev AV. Increased Retinal Metabolism Induced by Flicker in the Isolated Mouse Retina. eNeuro 2024; 11:ENEURO.0509-23.2024. [PMID: 38641415 PMCID: PMC11089847 DOI: 10.1523/eneuro.0509-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 04/10/2024] [Accepted: 04/12/2024] [Indexed: 04/21/2024] Open
Abstract
Both the retina and brain exhibit neurovascular coupling, increased blood flow during increased neural activity. In the retina increased blood flow can be evoked by flickering light, but the magnitude of the metabolic change that underlies this is not known. Local changes in oxygen consumption (QO2) are difficult to measure in vivo when both supply and demand are changing. Here we isolated the C57BL/6J mouse retina and supplied it with oxygen from both sides of the tissue. Microelectrode recordings of PO2 were made in darkness and during 20 s of high scotopic flickering light at 1 Hz. Flicker led to a PO2 increase in the outer retina and a decrease in the inner retina, indicating that outer retinal QO2 (QOR) decreased and inner retinal QO2 (QIR) increased. A four-layer oxygen diffusion model was fitted to PO2 values obtained in darkness and at the end of flicker to determine the values of QOR and QIR. QOR in flicker was 76 ± 14% (mean and SD, n = 10) of QOR in darkness. The increase in QIR was smaller, 6.4 ± 5.0%. These metabolic changes are likely smaller than the maximum changes, because with no regeneration of pigment in the isolated retina, we limited the illumination. Further modeling indicated that at high illumination, QIR could increase by up to 45%, which is comparable to the magnitude of flow changes. This suggests that the blood flow increase is at least roughly matched to the increased metabolic demands of activity in the retina.
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Affiliation(s)
- Robert A Linsenmeier
- Departments of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208
- Neurobiology, Northwestern University, Evanston, Illinois 60208
- Department of Ophthalmology, Northwestern University, Chicago, Illinois 60611
| | - Andrey V Dmitriev
- Departments of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208
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2
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DiNuzzo M, Dienel GA, Behar KL, Petroff OA, Benveniste H, Hyder F, Giove F, Michaeli S, Mangia S, Herculano-Houzel S, Rothman DL. Neurovascular coupling is optimized to compensate for the increase in proton production from nonoxidative glycolysis and glycogenolysis during brain activation and maintain homeostasis of pH, pCO 2, and pO 2. J Neurochem 2024; 168:632-662. [PMID: 37150946 PMCID: PMC10628336 DOI: 10.1111/jnc.15839] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 04/22/2023] [Accepted: 05/02/2023] [Indexed: 05/09/2023]
Abstract
During transient brain activation cerebral blood flow (CBF) increases substantially more than cerebral metabolic rate of oxygen consumption (CMRO2) resulting in blood hyperoxygenation, the basis of BOLD-fMRI contrast. Explanations for the high CBF versus CMRO2 slope, termed neurovascular coupling (NVC) constant, focused on maintenance of tissue oxygenation to support mitochondrial ATP production. However, paradoxically the brain has a 3-fold lower oxygen extraction fraction (OEF) than other organs with high energy requirements, like heart and muscle during exercise. Here, we hypothesize that the NVC constant and the capillary oxygen mass transfer coefficient (which in combination determine OEF) are co-regulated during activation to maintain simultaneous homeostasis of pH and partial pressure of CO2 and O2 (pCO2 and pO2). To test our hypothesis, we developed an arteriovenous flux balance model for calculating blood and brain pH, pCO2, and pO2 as a function of baseline OEF (OEF0), CBF, CMRO2, and proton production by nonoxidative metabolism coupled to ATP hydrolysis. Our model was validated against published brain arteriovenous difference studies and then used to calculate pH, pCO2, and pO2 in activated human cortex from published calibrated fMRI and PET measurements. In agreement with our hypothesis, calculated pH, pCO2, and pO2 remained close to constant independently of CMRO2 in correspondence to experimental measurements of NVC and OEF0. We also found that the optimum values of the NVC constant and OEF0 that ensure simultaneous homeostasis of pH, pCO2, and pO2 were remarkably similar to their experimental values. Thus, the high NVC constant is overall determined by proton removal by CBF due to increases in nonoxidative glycolysis and glycogenolysis. These findings resolve the paradox of the brain's high CBF yet low OEF during activation, and may contribute to explaining the vulnerability of brain function to reductions in blood flow and capillary density with aging and neurovascular disease.
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Affiliation(s)
| | - Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205 USA
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, NM, 87131 USA
| | - Kevin L Behar
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06511 USA
| | - Ognen A Petroff
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06511 USA
| | - Helene Benveniste
- Department of Anesthesiology, Yale University, New Haven, CT, 06520 USA
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520 USA
| | - Fahmeed Hyder
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520 USA
- Department of Radiology, Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, 06520 USA
| | - Federico Giove
- Centro Ricerche Enrico Fermi, Rome, RM, 00184 Italy
- Fondazione Santa Lucia IRCCS, Rome, RM, 00179 Italy
| | - Shalom Michaeli
- Department of Radiology, Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN, 55455 USA
| | - Silvia Mangia
- Department of Radiology, Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN, 55455 USA
| | - Suzana Herculano-Houzel
- Department of Psychology, Vanderbilt University, Nashville, TN
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN
| | - Douglas L Rothman
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520 USA
- Department of Radiology, Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, 06520 USA
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3
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Zhong X, Liang Y, Wang X, Lan H, Bai X, Jin L, Guan BO. Free-moving-state microscopic imaging of cerebral oxygenation and hemodynamics with a photoacoustic fiberscope. LIGHT, SCIENCE & APPLICATIONS 2024; 13:5. [PMID: 38163847 PMCID: PMC10758391 DOI: 10.1038/s41377-023-01348-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 11/22/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024]
Abstract
We report the development of a head-mounted photoacoustic fiberscope for cerebral imaging in a freely behaving mouse. The 4.5-gram imaging probe has a 9-µm lateral resolution and 0.2-Hz frame rate over a 1.2-mm wide area. The probe can continuously monitor cerebral oxygenation and hemodynamic responses at single-vessel resolution, showing significantly different cerebrovascular responses to external stimuli under anesthesia and in the freely moving state. For example, when subjected to high-concentration CO2 respiration, enhanced oxygenation to compensate for hypercapnia can be visualized due to cerebral regulation in the freely moving state. Comparative studies exhibit significantly weakened compensation capabilities in obese rodents. This new imaging modality can be used for investigating both normal and pathological cerebrovascular functions and shows great promise for studying cerebral activity, disorders and their treatments.
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Affiliation(s)
- Xiaoxuan Zhong
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Yizhi Liang
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Xiaoyu Wang
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Haoying Lan
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Xue Bai
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Long Jin
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China.
| | - Bai-Ou Guan
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China.
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4
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Ren Y, Senarathna J, Chu X, Grayson WL, Pathak AP. Vascular-centric mapping of in vivo blood oxygen saturation in preclinical models. Microvasc Res 2023; 148:104518. [PMID: 36894024 DOI: 10.1016/j.mvr.2023.104518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 01/27/2023] [Accepted: 03/01/2023] [Indexed: 03/09/2023]
Abstract
Assessing intravascular blood oxygen saturation (SO2) is crucial for characterizing in vivo microenvironmental changes in preclinical models of injury and disease. However, most conventional optical imaging techniques for mapping in vivo SO2 assume or compute a single value of the optical path-length in tissue. This is especially detrimental when mapping in vivo SO2 in experimental disease or wound healing models that are characterized by vascular and tissue remodeling. Therefore, to circumvent this limitation we developed an in vivo SO2 mapping technique that utilizes hemoglobin-based intrinsic optical signal (IOS) imaging combined with a vascular-centric estimation of optical path-lengths. In vivo arterial and venous SO2 distributions derived with this approach closely matched those reported in the literature, while those derived using the single path-length (i.e. conventional) approach did not. Moreover, in vivo cerebrovascular SO2 strongly correlated (R2 > 0.7) with changes in systemic SO2 measured with a pulse oximeter during hypoxia and hyperoxia paradigms. Finally, in a calvarial bone healing model, in vivo SO2 assessed over four weeks was spatiotemporally correlated with angiogenesis and osteogenesis (R2 > 0.6). During the early stages of bone healing (i.e. day 10), angiogenic vessels surrounding the calvarial defect exhibited mean SO2 that was elevated by10 % (p < 0.05) relative to that observed at a later stage (i.e., day 26), indicative of their role in osteogenesis. These correlations were not evident with the conventional SO2 mapping approach. The feasibility of our wide field-of-view in vivo SO2 mapping approach illustrates its potential for characterizing the microvascular environment in applications ranging from tissue engineering to cancer.
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Affiliation(s)
- Yunke Ren
- Depts. of Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Janaka Senarathna
- Russell H. Morgan Department of Radiology and Radiological Sciences, the Johns Hopkins University School of Medicine, Baltimore, MD, USA; Kavli Neuroscience Discovery Institute, the Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xinying Chu
- Depts. of Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Warren L Grayson
- Depts. of Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, MD, USA; Depts. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA; Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA; Translational Tissue Engineering Center, Johns Hopkins University, Baltimore, MD, USA; Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA
| | - Arvind P Pathak
- Depts. of Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Sciences, the Johns Hopkins University School of Medicine, Baltimore, MD, USA; The Sidney Kimmel Comprehensive Cancer Center, the Johns Hopkins University School of Medicine, Baltimore, MD, USA; Electrical Engineering, Johns Hopkins University, Baltimore, MD, USA; Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.
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5
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Moyaert P, Padrela BE, Morgan CA, Petr J, Versijpt J, Barkhof F, Jurkiewicz MT, Shao X, Oyeniran O, Manson T, Wang DJJ, Günther M, Achten E, Mutsaerts HJMM, Anazodo UC. Imaging blood-brain barrier dysfunction: A state-of-the-art review from a clinical perspective. Front Aging Neurosci 2023; 15:1132077. [PMID: 37139088 PMCID: PMC10150073 DOI: 10.3389/fnagi.2023.1132077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 03/15/2023] [Indexed: 05/05/2023] Open
Abstract
The blood-brain barrier (BBB) consists of specialized cells that tightly regulate the in- and outflow of molecules from the blood to brain parenchyma, protecting the brain's microenvironment. If one of the BBB components starts to fail, its dysfunction can lead to a cascade of neuroinflammatory events leading to neuronal dysfunction and degeneration. Preliminary imaging findings suggest that BBB dysfunction could serve as an early diagnostic and prognostic biomarker for a number of neurological diseases. This review aims to provide clinicians with an overview of the emerging field of BBB imaging in humans by answering three key questions: (1. Disease) In which diseases could BBB imaging be useful? (2. Device) What are currently available imaging methods for evaluating BBB integrity? And (3. Distribution) what is the potential of BBB imaging in different environments, particularly in resource limited settings? We conclude that further advances are needed, such as the validation, standardization and implementation of readily available, low-cost and non-contrast BBB imaging techniques, for BBB imaging to be a useful clinical biomarker in both resource-limited and well-resourced settings.
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Affiliation(s)
- Paulien Moyaert
- Department of Medical Imaging, Ghent University Hospital, Ghent, Belgium
- Lawson Health Research Institute, London, ON, Canada
- Department of Neurology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
- *Correspondence: Paulien Moyaert,
| | - Beatriz E. Padrela
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Amsterdam Neuroscience, Brain Imaging, Amsterdam, Netherlands
| | - Catherine A. Morgan
- School of Psychology and Centre for Brain Research, The University of Auckland, Auckland, New Zealand
- Centre for Advanced MRI, Auckland UniServices Limited, Auckland, New Zealand
| | - Jan Petr
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Amsterdam Neuroscience, Brain Imaging, Amsterdam, Netherlands
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany
| | - Jan Versijpt
- Department of Neurology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Frederik Barkhof
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Amsterdam Neuroscience, Brain Imaging, Amsterdam, Netherlands
- Queen Square Institute of Neurology and Centre for Medical Image Computing, University College London, London, United Kingdom
| | | | - Xingfeng Shao
- Laboratory of FMRI Technology (LOFT), USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Olujide Oyeniran
- Lawson Health Research Institute, London, ON, Canada
- Department of Medical Biophysics, Western University, London, ON, Canada
| | - Tabitha Manson
- Centre for Advanced MRI, Auckland UniServices Limited, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Danny J. J. Wang
- Laboratory of FMRI Technology (LOFT), USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Matthias Günther
- Fraunhofer Institute for Digital Medicine, University of Bremen, Bremen, Germany
| | - Eric Achten
- Department of Medical Imaging, Ghent University Hospital, Ghent, Belgium
| | - Henk J. M. M. Mutsaerts
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Amsterdam Neuroscience, Brain Imaging, Amsterdam, Netherlands
| | - Udunna C. Anazodo
- Lawson Health Research Institute, London, ON, Canada
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
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6
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Kim JH, Taylor AJ, Himmelbach M, Hagberg GE, Scheffler K, Ress D. Characterization of the blood oxygen level dependent hemodynamic response function in human subcortical regions with high spatiotemporal resolution. Front Neurosci 2022; 16:1009295. [PMID: 36303946 PMCID: PMC9592726 DOI: 10.3389/fnins.2022.1009295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Subcortical brain regions are absolutely essential for normal human function. These phylogenetically early brain regions play critical roles in human behaviors such as the orientation of attention, arousal, and the modulation of sensory signals to cerebral cortex. Despite the critical health importance of subcortical brain regions, there has been a dearth of research on their neurovascular responses. Blood oxygen level dependent (BOLD) functional MRI (fMRI) experiments can help fill this gap in our understanding. The BOLD hemodynamic response function (HRF) evoked by brief (<4 s) neural activation is crucial for the interpretation of fMRI results because linear analysis between neural activity and the BOLD response relies on the HRF. Moreover, the HRF is a consequence of underlying local blood flow and oxygen metabolism, so characterization of the HRF enables understanding of neurovascular and neurometabolic coupling. We measured the subcortical HRF at 9.4T and 3T with high spatiotemporal resolution using protocols that enabled reliable delineation of HRFs in individual subjects. These results were compared with the HRF in visual cortex. The HRF was faster in subcortical regions than cortical regions at both field strengths. There was no significant undershoot in subcortical areas while there was a significant post-stimulus undershoot that was tightly coupled with its peak amplitude in cortex. The different BOLD temporal dynamics indicate different vascular dynamics and neurometabolic responses between cortex and subcortical nuclei.
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Affiliation(s)
- Jung Hwan Kim
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Amanda J. Taylor
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Marc Himmelbach
- Division of Neuropsychology, Center of Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Gisela E. Hagberg
- High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Department of Biomedical Magnetic Resonance, Eberhard Karl’s University of Tübingen and University Hospital, Tübingen, Germany
| | - Klaus Scheffler
- High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Department of Biomedical Magnetic Resonance, Eberhard Karl’s University of Tübingen and University Hospital, Tübingen, Germany
| | - David Ress
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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7
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Chong SH, Ong YH, El Khatib M, Allu SR, Parthasarathy AB, Greenberg JH, Yodh AG, Vinogradov SA. Real-time tracking of brain oxygen gradients and blood flow during functional activation. NEUROPHOTONICS 2022; 9:045006. [PMID: 36457848 PMCID: PMC9704417 DOI: 10.1117/1.nph.9.4.045006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Accepted: 11/01/2022] [Indexed: 06/11/2023]
Abstract
Significance Cerebral metabolic rate of oxygen ( CMRO 2 ) consumption is a key physiological variable that characterizes brain metabolism in a steady state and during functional activation. Aim We aim to develop a minimally invasive optical technique for real-time measurement of CMRO 2 concurrently with cerebral blood flow (CBF). Approach We used a pair of macromolecular phosphorescent probes with nonoverlapping optical spectra, which were localized in the intra- and extravascular compartments of the brain tissue, thus providing a readout of oxygen gradients between these two compartments. In parallel, we measured CBF using laser speckle contrast imaging. Results The method enables computation and tracking of CMRO 2 during functional activation with high temporal resolution ( ∼ 7 Hz ). In contrast to other approaches, our assessment of CMRO 2 does not require measurements of CBF or hemoglobin oxygen saturation. Conclusions The independent records of intravascular and extravascular partial pressures of oxygen, CBF, and CMRO 2 provide information about the physiological events that accompany neuronal activation, creating opportunities for dynamic quantification of brain metabolism.
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Affiliation(s)
- Sang Hoon Chong
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Yi Hong Ong
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, Department of Radiation Oncology, Philadelphia, Pennsylvania, United States
| | - Mirna El Khatib
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Srinivasa Rao Allu
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Ashwin B. Parthasarathy
- University of South Florida, Department of Electrical Engineering, Tampa, Florida, United States
| | - Joel H. Greenberg
- University of Pennsylvania, Department of Neurology, Philadelphia, Pennsylvania, United States
| | - Arjun G. Yodh
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
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8
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Şencan İ, Esipova T, Kılıç K, Li B, Desjardins M, Yaseen MA, Wang H, Porter JE, Kura S, Fu B, Secomb TW, Boas DA, Vinogradov SA, Devor A, Sakadžić S. Optical measurement of microvascular oxygenation and blood flow responses in awake mouse cortex during functional activation. J Cereb Blood Flow Metab 2022; 42:510-525. [PMID: 32515672 PMCID: PMC8985437 DOI: 10.1177/0271678x20928011] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The cerebral cortex has a number of conserved morphological and functional characteristics across brain regions and species. Among them, the laminar differences in microvascular density and mitochondrial cytochrome c oxidase staining suggest potential laminar variability in the baseline O2 metabolism and/or laminar variability in both O2 demand and hemodynamic response. Here, we investigate the laminar profile of stimulus-induced intravascular partial pressure of O2 (pO2) transients to stimulus-induced neuronal activation in fully awake mice using two-photon phosphorescence lifetime microscopy. Our results demonstrate that stimulus-induced changes in intravascular pO2 are conserved across cortical layers I-IV, suggesting a tightly controlled neurovascular response to provide adequate O2 supply across cortical depth. In addition, we observed a larger change in venular O2 saturation (ΔsO2) compared to arterioles, a gradual increase in venular ΔsO2 response towards the cortical surface, and absence of the intravascular "initial dip" previously reported under anesthesia. This study paves the way for quantification of layer-specific cerebral O2 metabolic responses, facilitating investigation of brain energetics in health and disease and informed interpretation of laminar blood oxygen level dependent functional magnetic resonance imaging signals.
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Affiliation(s)
- İkbal Şencan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Tatiana Esipova
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Kıvılcım Kılıç
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Michèle Desjardins
- Department of Physics, Engineering Physics and Optics, Université Laval, QC, Canada
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Hui Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jason E Porter
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Sreekanth Kura
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Department of Biomedical Engineering, Boston University, Boston, MA, USA.,Department of Neurosciences, University of California San Diego, La Jolla, CA, USA.,Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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9
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Lacy TC, Robinson PA, Aquino KM, Pang JC. Cortical depth-dependent modeling of visual hemodynamic responses. J Theor Biol 2021; 535:110978. [PMID: 34952032 DOI: 10.1016/j.jtbi.2021.110978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/18/2021] [Accepted: 12/01/2021] [Indexed: 11/15/2022]
Abstract
A physiologically based three-dimensional (3D) hemodynamic model is developed to predict the experimentally observed blood oxygen level dependent (BOLD) responses versus the cortical depth induced by visual stimuli. Prior 2D approximations are relaxed in order to analyze 3D blood flow dynamics as a function of cortical depth. Comparison of the predictions with experimental data for evoked stimuli demonstrates that the full 3D model performs at least as well as previous approaches while remaining parsimonious. In particular, the 3D model requires significantly fewer assumptions and model parameters than previous models such that there is no longer need to define depth-specific parameter values for spatial spreading, peak amplitude, and hemodynamic velocity.
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Affiliation(s)
- Thomas C Lacy
- School of Physics, University of Sydney, New South Wales, Australia; Center for Integrative Brain Function, University of Sydney, New South Wales, Australia
| | - Peter A Robinson
- School of Physics, University of Sydney, New South Wales, Australia; Center for Integrative Brain Function, University of Sydney, New South Wales, Australia
| | - Kevin M Aquino
- School of Physics, University of Sydney, New South Wales, Australia; The Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia
| | - James C Pang
- The Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia; QIMR Berghofer Medical Research Institute, Queensland, Australia.
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10
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Zhu J, Liu C, Liu Y, Chen J, Zhang Y, Yao K, Wang L. Self-Fluence-Compensated Functional Photoacoustic Microscopy. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:3856-3866. [PMID: 34310295 DOI: 10.1109/tmi.2021.3099820] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Optical-resolution photoacoustic microscopy (OR-PAM) can image blood oxygen saturation (sO2) in vivo with high resolution and excellent sensitivity and offers a great tool for neurovascular study and early cancer diagnosis. OR-PAM ignores the wavelength-dependent optical attenuation in superficial tissue, which cause errors in sO2 imaging. Monte Carlo simulation shows that variations in imaging depth, vessel diameter, and focal position can cause up to ∼ 60 % decrease in sO2 imaging. Here, we develop a self-fluence-compensated OR-PAM to compensate for the wavelength-dependent fluence attenuation. We propose a linearized model to estimate the fluence attenuations and use three optical wavelengths to compensate for them in sO2 calculation. We validate the model in both numerical and physical phantoms and show that the compensation method can effectively reduce the sO2 errors. In functional brain imaging, we demonstrate that the compensation method can effectively improve sO2 accuracy, especially in small vessels. Compared with uncompensated ones, the sO2 values are improved by 10~30% in the brain. We monitor ischemic-stroke-induced brain injury which demonstrates great potential for the pre-clinical study of vascular diseases.
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11
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Matsukawa K, Asahara R, Uzumaki M, Hashiguchi Y, Ishii K, Wang J, Smith SA. Central command-related increases in blood velocity of anterior cerebral artery and prefrontal oxygenation at the onset of voluntary tapping. Am J Physiol Heart Circ Physiol 2021; 321:H518-H531. [PMID: 34328343 DOI: 10.1152/ajpheart.00062.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The anterior cerebral artery (ACA) supplies blood predominantly to the frontal lobe including the prefrontal cortex. Our laboratory reported that prefrontal oxygenated-hemoglobin concentration (Oxy-Hb) increased before and at exercise onset, as long as exercise is arbitrarily started. Moreover, the increased prefrontal oxygenation seems independent of both exercise intensity and muscle mass. If so, mean blood velocity of the ACA (ACABV) should increase with "very light motor effort," concomitantly with the preexercise and initial increase in prefrontal Oxy-Hb. This study aimed to examine the responses in ACABV and vascular conductance index (ACAVCI) of the ACA as well as prefrontal Oxy-Hb during arbitrary or cued finger tapping in 12 subjects, an activity with a Borg scale perceived exertion rating of 7 (median). With arbitrary start, ACABV increased at tapping onset (14 ± 9%) via an elevation in ACAVCI. Likewise, prefrontal Oxy-Hb increased at the onset of tapping with a time course resembling that of ACABV. A positive cross correlation between the initial changes in ACABV and prefrontal Oxy-Hb was found significant in 67% of subjects, having a time lag of 2 s, whereas a positive linear regression between them was significant in 75% of subjects. When tapping was forced to start by cue, the initial increases in ACABV, ACAVCI, and prefrontal Oxy-Hb were delayed and blunted as compared with an arbitrary start. Thus, active vasodilatation of the ACA vascular bed occurs at tapping onset, as long as tapping is arbitrarily started, and contributes to immediate increases in blood flow and prefrontal oxygenation.NEW & NOTEWORTHY Anterior cerebral artery blood velocity and vascular conductance index along with prefrontal oxygenated-hemoglobin concentration all increased at the onset of finger tapping, peaking immediately after tapping onset, as long as tapping was arbitrarily started. Positive cross correlation and linear regression between the increases in ACABV and prefrontal Oxy-Hb were significant in 67%-75% of subjects. Active vasodilatation of the ACA vascular bed occurs with arbitrary tapping onset and contributes to increased ACABV and prefrontal oxygenation.
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Affiliation(s)
- Kanji Matsukawa
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.,Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Ryota Asahara
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Minami Uzumaki
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yoshiki Hashiguchi
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kei Ishii
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Jijia Wang
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Scott A Smith
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
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12
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Fukuda M, Poplawsky AJ, Kim SG. Time-dependent spatial specificity of high-resolution fMRI: insights into mesoscopic neurovascular coupling. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190623. [PMID: 33190606 PMCID: PMC7741035 DOI: 10.1098/rstb.2019.0623] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
High-resolution functional magnetic resonance imaging (fMRI) is becoming increasingly popular because of the growing availability of ultra-high magnetic fields which are capable of improving sensitivity and spatial resolution. However, it is debatable whether increased spatial resolutions for haemodynamic-based techniques, like fMRI, can accurately detect the true location of neuronal activity. We have addressed this issue in functional columns and layers of animals with haemoglobin-based optical imaging and different fMRI contrasts, such as blood oxygenation level-dependent, cerebral blood flow and cerebral blood volume fMRI. In this review, we describe empirical evidence primarily from our own studies on how well these fMRI signals are spatially specific to the neuronally active site and discuss insights into neurovascular coupling at the mesoscale. This article is part of the theme issue 'Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity'.
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Affiliation(s)
- Mitsuhiro Fukuda
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, South Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea
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13
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Matsukawa K, Asahara R, Ishii K, Kunishi M, Yamashita Y, Hashiguchi Y, Liang N, Smith SA. Increased prefrontal oxygenation prior to and at the onset of over-ground locomotion in humans. J Appl Physiol (1985) 2020; 129:1161-1172. [DOI: 10.1152/japplphysiol.00392.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We found using wireless near-infrared spectroscopy that prefrontal oxygenation increased before the onset of arbitrary over-ground walking, whereas the preexercise increase was absent when walking was suddenly started by cue. The difference in prefrontal oxygenation between start modes (considered related to central command) preceded heart rate response variances and demonstrated a positive relationship with the difference in heart rate. The central command-related prefrontal activity may contribute to cardiac adjustment, synchronized with the beginning of over-ground walking.
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Affiliation(s)
- Kanji Matsukawa
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Ryota Asahara
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan
| | - Kei Ishii
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan
| | - Mayo Kunishi
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yurino Yamashita
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yoshiki Hashiguchi
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Nan Liang
- Cognitive Motor Neuroscience, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Scott A. Smith
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
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14
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He Y, Wang M, Yu X. High spatiotemporal vessel-specific hemodynamic mapping with multi-echo single-vessel fMRI. J Cereb Blood Flow Metab 2020; 40:2098-2114. [PMID: 31696765 PMCID: PMC7786852 DOI: 10.1177/0271678x19886240] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
High-resolution fMRI enables noninvasive mapping of the hemodynamic responses from individual penetrating vessels in animal brains. Here, a 2D multi-echo single-vessel fMRI (MESV-fMRI) method has been developed to map the fMRI signal from arterioles and venules with a 100 ms sampling rate at multiple echo times (TE, 3-30 ms) and short acquisition windows (<1 ms). The T2*-weighted signal shows the increased extravascular effect on venule voxels as a function of TE. In contrast, the arteriole voxels show an increased fMRI signal with earlier onset than venules voxels at the short TE (3 ms) with increased blood inflow and volume effects. MESV-fMRI enables vessel-specific T2* mapping and presents T2*-based fMRI time courses with higher contrast-to-noise ratios (CNRs) than the T2*-weighted fMRI signal at a given TE. The vessel-specific T2* mapping also allows semi-quantitative estimation of the oxygen saturation levels (Y) and their changes (ΔY) at a given blood volume fraction upon neuronal activation. The MESV-fMRI method enables vessel-specific T2* measurements with high spatiotemporal resolution for better modeling of the fMRI signal based on the hemodynamic parameters.
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Affiliation(s)
- Yi He
- Translational Neuroimaging and Neural Control Group, High Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tuebingen, Tuebingen, Germany.,Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - Maosen Wang
- Translational Neuroimaging and Neural Control Group, High Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tuebingen, Tuebingen, Germany
| | - Xin Yu
- Translational Neuroimaging and Neural Control Group, High Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
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15
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Kim JH, Taylor AJ, Wang DJJ, Zou X, Ress D. Dynamics of the cerebral blood flow response to brief neural activity in human visual cortex. J Cereb Blood Flow Metab 2020; 40:1823-1837. [PMID: 31429358 PMCID: PMC7446561 DOI: 10.1177/0271678x19869034] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The blood oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal depends on an interplay of cerebral blood flow (CBF), oxygen metabolism, and cerebral blood volume. Despite wide usage of BOLD fMRI, it is not clear how these physiological components create the BOLD signal. Here, baseline CBF and its dynamics evoked by a brief stimulus (2 s) in human visual cortex were measured at 3T. We found a stereotypical CBF response: immediate increase, rising to a peak a few second after the stimulus, followed by a significant undershoot. The BOLD hemodynamic response function (HRF) was also measured in the same session. Strong correlations between HRF and CBF peak responses indicate that the flow responses evoked by neural activation in nearby gray matter drive the early HRF. Remarkably, peak CBF and HRF were also strongly modulated by baseline perfusion. The CBF undershoot was reliable and significantly correlated with the HRF undershoot. However, late-time dynamics of the HRF and CBF suggest that oxygen metabolism can also contribute to the HRF undershoot. Combined measurement of the CBF and HRF for brief neural activation is a useful tool to understand the temporal dynamics of neurovascular and neurometabolic coupling.
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Affiliation(s)
- Jung Hwan Kim
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Amanda J Taylor
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Danny JJ Wang
- Laboratory of FMRI Technology (LOFT), Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, USA
| | - Xiaowei Zou
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - David Ress
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- David Ress, Baylor College of Medicine, 1 Baylor Plaza T115E, Houston, TX 77030, USA.
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16
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Secomb TW, Bullock KV, Boas DA, Sakadžić S. The mass transfer coefficient for oxygen transport from blood to tissue in cerebral cortex. J Cereb Blood Flow Metab 2020; 40:1634-1646. [PMID: 31423930 PMCID: PMC7370375 DOI: 10.1177/0271678x19870068] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The functioning of cerebral cortex depends on adequate tissue oxygenation. MRI-based techniques allow estimation of blood oxygen levels, tissue perfusion, and oxygen consumption rate (CMRO2), but do not directly measure partial pressure of oxygen (PO2) in tissue. To address the estimation of tissue PO2, the oxygen mass transfer coefficient (KTO2) is here defined as the CMRO2 divided by the difference in spatially averaged PO2 between blood and tissue, and is estimated by analyzing Krogh-cylinder type models. Resistance to radial diffusion of oxygen from microvessels to tissue is distributed within vessels and in the extravascular tissue. The value of KTO2 is shown to depend strongly on vascular length density and also on microvessel tube hematocrits and diameters, but to be insensitive to blood flow rate and to transient changes in flow or oxygen consumption. Estimated values of KTO2 are higher than implied by previous studies, implying smaller declines in PO2 from blood to tissue. Average tissue PO2 can be estimated from MRI-based measurements as average blood PO2 minus the product of KTO2 and CMRO2. For oxygen consumption rates and vascular densities typical of mouse cortex, the predicted difference between average blood and tissue PO2 is about 10 mmHg.
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Affiliation(s)
- Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, USA.,Program in Applied Mathematics, University of Arizona, Tucson, AZ, USA.,Physiological Sciences Graduate Program, University of Arizona, Tucson, AZ, USA
| | - Katherine V Bullock
- Physiological Sciences Graduate Program, University of Arizona, Tucson, AZ, USA
| | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.,Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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17
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Shim H, Lee J, Kim S. BOLD fMRI and hemodynamic responses to somatosensory stimulation in anesthetized mice: spontaneous breathing vs. mechanical ventilation. NMR IN BIOMEDICINE 2020; 33:e4311. [PMID: 32297409 PMCID: PMC7317444 DOI: 10.1002/nbm.4311] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/26/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
Mouse functional MRI (fMRI) has been of great interest due to the abundance of transgenic models. Due to a mouse's small size, spontaneous breathing has often been used. Because the vascular physiology affecting fMRI might not be controlled normally, its effects on functional responses were investigated with optical intrinsic signal (OIS) imaging and 9.4 T BOLD fMRI. Three conditions were tested in C57BL/6 mice: spontaneous breathing under ketamine and xylazine anesthesia (KX), mechanical ventilation under KX, and mechanical ventilation under isoflurane. Spontaneous breathing under KX induced an average pCO2 of 83 mmHg, whereas a mechanical ventilation condition achieved a pCO2 of 37-41 mmHg within a physiological range. The baseline diameter of arterial and venous vessels was only 7%-9% larger with spontaneous breathing than with mechanical ventilation under KX, but it was much smaller than that in normocapnic isoflurane-anesthetized mice. Three major functional studies were performed. First, CBV-weighted OIS and arterial dilations to 4-second forepaw stimulation were rapid and larger at normocapnia than hypercapnia under KX, but very small under isoflurane. Second, CBV-weighted OIS and arterial dilations by vasodilator acetazolamide were measured for investigating vascular reactivity and were larger in the normocapnic condition than in the hypercapnic condition under KX. Third, evoked OIS and BOLD fMRI responses in the contralateral mouse somatosensory cortex to 20-second forepaw stimulation were faster and larger in the mechanical ventilation than spontaneous breathing. BOLD fMRI peaked at the end of the 20-second stimulation under hypercapnic spontaneous breathing, and at ~9 seconds under mechanical ventilation. The peak amplitude of BOLD fMRI was 2.2% at hypercapnia and ~3.4% at normocapnia. Overall, spontaneous breathing induces sluggish reduced hemodynamic and fMRI responses, but it is still viable for KX anesthesia due to its simplicity, noninvasiveness, and well-localized BOLD activity in the somatosensory cortex.
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Affiliation(s)
- Hyun‐Ji Shim
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Health Sciences and Technology, SAIHSTSungkyunkwan UniversitySeoul06355Republic of Korea
| | - Joonyeol Lee
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Biomedical EngineeringSungkyunkwan UniversitySuwon16419Republic of Korea
| | - Seong‐Gi Kim
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Health Sciences and Technology, SAIHSTSungkyunkwan UniversitySeoul06355Republic of Korea
- Department of Biomedical EngineeringSungkyunkwan UniversitySuwon16419Republic of Korea
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18
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19
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Lu X, Moeini M, Li B, Thorin É, Lesage F. Hypertension accelerates cerebral tissue PO 2 disruption in Alzheimer's disease. Neurosci Lett 2020; 715:134626. [PMID: 31726177 DOI: 10.1016/j.neulet.2019.134626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 11/07/2019] [Accepted: 11/09/2019] [Indexed: 02/03/2023]
Abstract
This study measured stimulus-evoked brain tissue oxygenation changes in a mouse model of Alzheimer disease (AD) and further explored the influence of exercise and angiotensin II-induced hypertension on these changes. in vivo two-photon phosphorescence lifetime microscopy was used to investigate local changes in brain tissue oxygenation following whisker stimulation. During rest periods, PO2 values close to the arteriolar wall were lower in the AD groups and the PO2 spatial decay as a function of distance to arteriole was increased by hypertension. During stimulation, tissue PO2 response had a similar spatial dependence across groups. Tissue PO2 response in post-stimulation period was larger in AD groups (e.g., AD6 and ADH6) than in the controls (WT6 and WTH6). After a 3-month voluntary exercise period, some of these changes were reversed in AD mice. This provides novel insight into tissue oxygen delivery and the impact of blood pressure control and exercise on brain tissue oxygenation in AD.
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Affiliation(s)
- Xuecong Lu
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada; Montreal Heart Institute, Research Center, Montreal, Quebec, Canada
| | - Mohammad Moeini
- Department of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
| | - Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Éric Thorin
- Montreal Heart Institute, Research Center, Montreal, Quebec, Canada; Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada; Montreal Heart Institute, Research Center, Montreal, Quebec, Canada.
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20
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Havlicek M, Uludağ K. A dynamical model of the laminar BOLD response. Neuroimage 2020; 204:116209. [DOI: 10.1016/j.neuroimage.2019.116209] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 08/11/2019] [Accepted: 09/17/2019] [Indexed: 12/18/2022] Open
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21
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Zhang Q, Roche M, Gheres KW, Chaigneau E, Kedarasetti RT, Haselden WD, Charpak S, Drew PJ. Cerebral oxygenation during locomotion is modulated by respiration. Nat Commun 2019; 10:5515. [PMID: 31797933 PMCID: PMC6893036 DOI: 10.1038/s41467-019-13523-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 11/12/2019] [Indexed: 12/17/2022] Open
Abstract
In the brain, increased neural activity is correlated with increases of cerebral blood flow and tissue oxygenation. However, how cerebral oxygen dynamics are controlled in the behaving animal remains unclear. We investigated to what extent cerebral oxygenation varies during locomotion. We measured oxygen levels in the cortex of awake, head-fixed mice during locomotion using polarography, spectroscopy, and two-photon phosphorescence lifetime measurements of oxygen sensors. We find that locomotion significantly and globally increases cerebral oxygenation, specifically in areas involved in locomotion, as well as in the frontal cortex and the olfactory bulb. The oxygenation increase persists when neural activity and functional hyperemia are blocked, occurred both in the tissue and in arteries feeding the brain, and is tightly correlated with respiration rate and the phase of respiration cycle. Thus, breathing rate is a key modulator of cerebral oxygenation and should be monitored during hemodynamic imaging, such as in BOLD fMRI.
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Affiliation(s)
- Qingguang Zhang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
| | - Morgane Roche
- Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.,Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France
| | - Kyle W Gheres
- Graduate Program in Molecular Cellular and Integrative Biosciences, The Pennsylvania State University, University Park, PA, USA
| | - Emmanuelle Chaigneau
- Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.,Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France
| | - Ravi T Kedarasetti
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
| | - William D Haselden
- Medical Scientist Training Program and Neuroscience Graduate Program, The Pennsylvania State University, University Park, PA, USA
| | - Serge Charpak
- Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.,Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France
| | - Patrick J Drew
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA. .,Department of Neurosurgery and Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA.
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22
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Taylor AJ, Kim JH, Singh V, Halfen EJ, Pfeuffer J, Ress D. More than BOLD: Dual-spin populations create functional contrast. Magn Reson Med 2019; 83:681-694. [PMID: 31423634 DOI: 10.1002/mrm.27941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/16/2019] [Accepted: 07/21/2019] [Indexed: 11/06/2022]
Abstract
PURPOSE Functional MRI contrast has generally been associated with changes in transverse relaxivity caused by blood oxygen concentration, the so-called blood oxygen level dependent contrast. However, this interpretation of fMRI contrast has been called into question by several recent experiments at high spatial resolution. Experiments were conducted to examine contrast dependencies that cannot be explained only by differences in relaxivity in a single-spin population. METHODS Measurements of functional signal and contrast were obtained in human early visual cortex during a high-contrast visual stimulation over a large range of TEs and for several flip angles. Small voxels (1.5 mm) were used to restrict the measurements to cortical gray matter in early visual areas identified using retinotopic mapping procedures. RESULTS Measurements were consistent with models that include 2 spin populations. The dominant population has a relatively short transverse lifetime that is strongly modulated by activation. However, functional contrast is also affected by volume changes between this short-lived population and the longer-lived population. CONCLUSION Some of the previously observed "nonclassical" behaviors of functional contrast can be explained by these interacting dual-spin populations.
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Affiliation(s)
- Amanda J Taylor
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Jung H Kim
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | | | | | - Josef Pfeuffer
- Siemens Healthcare, Application Development, Erlangen, Germany
| | - David Ress
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
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23
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Chaigneau E, Roche M, Charpak S. Unbiased Analysis Method for Measurement of Red Blood Cell Size and Velocity With Laser Scanning Microscopy. Front Neurosci 2019; 13:644. [PMID: 31316334 PMCID: PMC6610068 DOI: 10.3389/fnins.2019.00644] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 06/05/2019] [Indexed: 12/28/2022] Open
Abstract
Two-photon laser scanning microscopy is widely used to measure blood hemodynamics in brain blood vessels. Still, the algorithms used so far to extract red blood cell (RBC) size and velocity from line-scan acquisitions have ignored the extent to which scanning speed influences the measurements. Here, we used a theoretical approach that takes into account the velocity and direction of both scanning mirrors and RBCs during acquisition to provide an algorithm that measures the real RBC size and velocity. We validate our approach in brain vessels of anesthetized mice, and demonstrate that it corrects online measurement errors that can reach several 10s of percent as well as data previously acquired. To conclude, our analysis allows unbiased comparisons of blood hemodynamic parameters from brain capillaries and large vessels in control and pathological animal models.
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Affiliation(s)
| | | | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris, France
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24
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Schneider J, Berndt N, Papageorgiou IE, Maurer J, Bulik S, Both M, Draguhn A, Holzhütter HG, Kann O. Local oxygen homeostasis during various neuronal network activity states in the mouse hippocampus. J Cereb Blood Flow Metab 2019; 39:859-873. [PMID: 29099662 PMCID: PMC6501513 DOI: 10.1177/0271678x17740091] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cortical information processing comprises various activity states emerging from timed synaptic excitation and inhibition. However, the underlying energy metabolism is widely unknown. We determined the cerebral metabolic rate of oxygen (CMRO2) along a tissue depth of <0.3 mm in the hippocampal CA3 region during various network activities, including gamma oscillations and sharp wave-ripples that occur during wakefulness and sleep. These physiological states associate with sensory perception and memory formation, and critically depend on perisomatic GABA inhibition. Moreover, we modelled vascular oxygen delivery based on quantitative microvasculature analysis. (1) Local CMRO2 was highest during gamma oscillations (3.4 mM/min), medium during sharp wave-ripples, asynchronous activity and isoflurane application (2.0-1.6 mM/min), and lowest during tetrodotoxin application (1.4 mM/min). (2) Energy expenditure of axonal and synaptic signaling accounted for >50% during gamma oscillations. (3) CMRO2 positively correlated with number and synchronisation of activated synapses, and neural multi-unit activity. (4) The median capillary distance was 44 µm. (5) The vascular oxygen partial pressure of 33 mmHg was needed to sustain oxidative phosphorylation during gamma oscillations. We conclude that gamma oscillations featuring high energetics require a hemodynamic response to match oxygen consumption of respiring mitochondria, and that perisomatic inhibition significantly contributes to the brain energy budget.
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Affiliation(s)
- Justus Schneider
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Nikolaus Berndt
- 2 Computational Systems Biochemistry, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Ismini E Papageorgiou
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Jana Maurer
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Sascha Bulik
- 2 Computational Systems Biochemistry, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Martin Both
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Andreas Draguhn
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Hermann-Georg Holzhütter
- 2 Computational Systems Biochemistry, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Oliver Kann
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
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25
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Hernandez-Garcia L, Lahiri A, Schollenberger J. Recent progress in ASL. Neuroimage 2019; 187:3-16. [PMID: 29305164 PMCID: PMC6030511 DOI: 10.1016/j.neuroimage.2017.12.095] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 12/21/2017] [Accepted: 12/30/2017] [Indexed: 11/26/2022] Open
Abstract
This article aims to provide the reader with an overview of recent developments in Arterial Spin Labeling (ASL) MRI techniques. A great deal of progress has been made in recent years in terms of the SNR and acquisition speed. New strategies have been introduced to improve labeling efficiency, reduce artefacts, and estimate other relevant physiological parameters besides perfusion. As a result, ASL techniques has become a reliable workhorse for researchers as well as clinicians. After a brief overview of the technique's fundamentals, this article will review new trends and variants in ASL including vascular territory mapping and velocity selective ASL, as well as arterial blood volume imaging techniques. This article will also review recent processing techniques to reduce partial volume effects and physiological noise. Next the article will examine how ASL techniques can be leveraged to calculate additional physiological parameters beyond perfusion and finally, it will review a few recent applications of ASL in the literature.
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Affiliation(s)
| | - Anish Lahiri
- FMRI Laboratory, University of Michigan, United States
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26
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Cerebral tissue pO 2 response to stimulation is preserved with age in awake mice. Neurosci Lett 2019; 699:160-166. [PMID: 30738870 DOI: 10.1016/j.neulet.2019.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/11/2019] [Accepted: 02/06/2019] [Indexed: 12/15/2022]
Abstract
Compromised oxygen supply to cerebral tissue could be an important mechanism contributing to age-related cognition decline. We recently showed in awake mice that resting cerebral tissue pO2 decreases with age, a phenomenon that manifests mainly after middle-age. To extend these findings, here we aimed to study how tissue pO2 response to neuronal stimulation is affected by aging. We used two-photon phosphorescence lifetime microscopy to directly measure the brain tissue pO2 response to whisker stimulation in healthy awake young, middle-aged and old mice. We show that despite a decrease in baseline tissue pO2, the amplitude of the tissue pO2 response to stimulation is well preserved with age. However, the response dynamics are altered towards a slower response with reduced post-stimulus undershoot in older ages, possibly due to stiffer vessel wall among other factors. An estimation of the net oxygen consumption rate using a modified Krogh model suggests that the O2 overshoot during stimulation may be necessary to secure a higher capillary O2 delivery to the tissue proportional to increased CMRO2 to maintain the capillary tissue pO2. It was observed that the coupling between the CMRO2 and capillary O2 delivery is preserved with age.
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27
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BOLD signal physiology: Models and applications. Neuroimage 2019; 187:116-127. [DOI: 10.1016/j.neuroimage.2018.03.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 02/14/2018] [Accepted: 03/08/2018] [Indexed: 12/14/2022] Open
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28
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Ohene Y, Harrison IF, Nahavandi P, Ismail O, Bird EV, Ottersen OP, Nagelhus EA, Thomas DL, Lythgoe MF, Wells JA. Non-invasive MRI of brain clearance pathways using multiple echo time arterial spin labelling: an aquaporin-4 study. Neuroimage 2018; 188:515-523. [PMID: 30557661 PMCID: PMC6414399 DOI: 10.1016/j.neuroimage.2018.12.026] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 11/30/2018] [Accepted: 12/12/2018] [Indexed: 12/26/2022] Open
Abstract
There is currently a lack of non-invasive tools to assess water transport in healthy and pathological brain tissue. Aquaporin-4 (AQP4) water channels are central to many water transport mechanisms, and emerging evidence also suggests that AQP4 plays a key role in amyloid-β (Aβ) clearance, possibly via the glymphatic system. Here, we present the first non-invasive technique sensitive to AQP4 channels polarised at the blood-brain interface (BBI). We apply a multiple echo time (multi-TE) arterial spin labelling (ASL) MRI technique to the mouse brain to assess BBI water permeability via calculation of the exchange time (Texw), the time for magnetically labelled intravascular water to exchange across the BBI. We observed a 31% increase in exchange time in AQP4-deficient (Aqp4-/-) mice (452 ± 90 ms) compared to their wild-type counterparts (343 ± 91 ms) (p = 0.01), demonstrating the sensitivity of the technique to the lack of AQP4 water channels. More established, quantitative MRI parameters: arterial transit time (δa), cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) detected no significant changes with the removal of AQP4. This clinically relevant tool may be crucial to better understand the role of AQP4 in water transport across the BBI, as well as clearance of proteins in neurodegenerative conditions such as Alzheimer's disease.
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Affiliation(s)
- Yolanda Ohene
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, UCL, London, UK
| | - Ian F Harrison
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, UCL, London, UK
| | - Payam Nahavandi
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, UCL, London, UK
| | - Ozama Ismail
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, UCL, London, UK
| | - Eleanor V Bird
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, UCL, London, UK
| | - Ole P Ottersen
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Erlend A Nagelhus
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - David L Thomas
- Neuroradiological Academic Unit, UCL Institute of Neurology, UCL, London, UK; Leonard Wolfson Experimental Neurology Centre, UCL Institute of Neurology, UCL, London, UK
| | - Mark F Lythgoe
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, UCL, London, UK
| | - Jack A Wells
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, UCL, London, UK.
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Rafl J, Kulhanek F, Kudrna P, Ort V, Roubik K. Response time of indirectly accessed gas exchange depends on measurement method. BIOMED ENG-BIOMED TE 2018; 63:647-655. [PMID: 28802098 DOI: 10.1515/bmt-2017-0070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 07/03/2017] [Indexed: 11/15/2022]
Abstract
Noninvasive techniques are routinely used for assessment of tissue effects of lung ventilation. However, comprehensive studies of the response time of the methods are scarce. The aim of this study was to compare the response time of noninvasive methods for monitoring of gas exchange to sudden changes in the composition of the inspired gas. A prospective experimental study with 16 healthy volunteers was conducted. A ventilation circuit was designed that enabled a fast change in the composition of the inspiratory gas mixture while allowing spontaneous breathing. The volunteers inhaled a hypoxic mixture, then a hypercapnic mixture, a hyperoxic mixture and finally a 0.3% CO mixture. The parameters with the fastest response to the sudden change of O2 in inhaled gas were peripheral capillary oxygen saturation (SpO2) and regional tissue oxygenation (rSO2). Transcutaneous oxygen partial pressure (tcpO2) had almost the same time of reaction, but its time of relaxation was 2-3 times longer. End-tidal carbon dioxide (EtCO2) response time to change of CO2 concentration in inhaled gas was less than half in comparison with transcutaneous carbon dioxide partial pressure (tcpCO2). All the examined parameters and devices reacted adequately to changes in gas concentration in the inspiratory gas mixture.
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Affiliation(s)
- Jakub Rafl
- Czech Technical University in Prague, Faculty of Biomedical Engineering, Department of Biomedical Technology, nam. Sitna 3105, 272 01 Kladno, Czech Republic, Phone: +420 728 229 991, Fax: +420 224 358 419
| | - Filip Kulhanek
- Czech Technical University in Prague, Faculty of Biomedical Engineering, Department of Biomedical Technology, 272 01 Kladno, Czech Republic
| | - Petr Kudrna
- Czech Technical University in Prague, Faculty of Biomedical Engineering, Department of Biomedical Technology, 272 01 Kladno, Czech Republic
| | - Vaclav Ort
- Czech Technical University in Prague, Faculty of Biomedical Engineering, Department of Biomedical Technology, 272 01 Kladno, Czech Republic
| | - Karel Roubik
- Czech Technical University in Prague, Faculty of Biomedical Engineering, Department of Biomedical Technology, 272 01 Kladno, Czech Republic
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30
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Boillat Y, Zwaag W. Whole brain measurements of the positive BOLD response variability during a finger tapping task at 7 T show regional differences in its profiles. Magn Reson Med 2018; 81:2720-2727. [DOI: 10.1002/mrm.27566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/18/2018] [Accepted: 09/21/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Yohan Boillat
- Laboratory for Functional and Metabolic Imaging Ecole Polytechnique Fédérale de Lausanne Lausanne Switzerland
| | - Wietske Zwaag
- Biomedical Imaging Research Center Ecole Polytechnique Fédérale de Lausanne Lausanne Switzerland
- Spinoza Centre for Neuroimaging Amsterdam Netherlands
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31
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Kim SG. Biophysics of BOLD fMRI investigated with animal models. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 292:82-89. [PMID: 29705033 DOI: 10.1016/j.jmr.2018.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 02/14/2018] [Accepted: 04/09/2018] [Indexed: 06/08/2023]
Abstract
The widely-used BOLD fMRI signal depends on various anatomical, physiological, and imaging parameters. Thus, it is important to examine its biophysical and physiological source in order to optimize, model and accurately interpret fMRI. Animal models have been used to investigate these issues to take systematic measurements and combine with conventional invasive approaches. Here, we reviewed and discussed multiple issues, including the echo time-dependent intravascular contribution and extravascular contributions, gradient-echo vs. spin-echo fMRI, the physiological source of BOLD fMRI, arterial vs. venous cerebral blood volume change, cerebral oxygen consumption change, and arterial oxygen saturation change. We then discuss future directions of animal fMRI and translation to human fMRI. Systematic biophysical BOLD fMRI studies provide insight into the modeling and interpretation of BOLD fMRI in animals and humans.
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Affiliation(s)
- Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Republic of Korea; Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
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32
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Michelson NJ, Vazquez AL, Eles JR, Salatino JW, Purcell EK, Williams JJ, Cui XT, Kozai TDY. Multi-scale, multi-modal analysis uncovers complex relationship at the brain tissue-implant neural interface: new emphasis on the biological interface. J Neural Eng 2018; 15:033001. [PMID: 29182149 PMCID: PMC5967409 DOI: 10.1088/1741-2552/aa9dae] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Implantable neural electrode devices are important tools for neuroscience research and have an increasing range of clinical applications. However, the intricacies of the biological response after implantation, and their ultimate impact on recording performance, remain challenging to elucidate. Establishing a relationship between the neurobiology and chronic recording performance is confounded by technical challenges related to traditional electrophysiological, material, and histological limitations. This can greatly impact the interpretations of results pertaining to device performance and tissue health surrounding the implant. APPROACH In this work, electrophysiological activity and immunohistological analysis are compared after controlling for motion artifacts, quiescent neuronal activity, and material failure of devices in order to better understand the relationship between histology and electrophysiological outcomes. MAIN RESULTS Even after carefully accounting for these factors, the presence of viable neurons and lack of glial scarring does not convey single unit recording performance. SIGNIFICANCE To better understand the biological factors influencing neural activity, detailed cellular and molecular tissue responses were examined. Decreases in neural activity and blood oxygenation in the tissue surrounding the implant, shift in expression levels of vesicular transporter proteins and ion channels, axon and myelin injury, and interrupted blood flow in nearby capillaries can impact neural activity around implanted neural interfaces. Combined, these tissue changes highlight the need for more comprehensive, basic science research to elucidate the relationship between biology and chronic electrophysiology performance in order to advance neural technologies.
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Affiliation(s)
| | - Alberto L Vazquez
- Department of Bioengineering, University of Pittsburgh
- Department of Radiology, University of Pittsburgh
- Center for the Neural Basis of Cognition, University of Pittsburgh
- Center for Neuroscience, University of Pittsburgh
| | - James R Eles
- Department of Bioengineering, University of Pittsburgh
- Center for the Neural Basis of Cognition, University of Pittsburgh
| | | | - Erin K Purcell
- Department of Biomedical Engineering, Michigan State University
| | | | - X. Tracy Cui
- Department of Bioengineering, University of Pittsburgh
- Center for the Neural Basis of Cognition, University of Pittsburgh
- McGowan Institute of Regenerative Medicine, University of Pittsburgh
| | - Takashi DY Kozai
- Department of Bioengineering, University of Pittsburgh
- Center for the Neural Basis of Cognition, University of Pittsburgh
- Center for Neuroscience, University of Pittsburgh
- McGowan Institute of Regenerative Medicine, University of Pittsburgh
- NeuroTech Center, University of Pittsburgh Brain Institute
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33
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Developing transmission line equations of oxygen transport for predicting oxygen distribution in the arterial system. Sci Rep 2018; 8:5369. [PMID: 29599481 PMCID: PMC5876338 DOI: 10.1038/s41598-018-23743-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/08/2018] [Indexed: 12/02/2022] Open
Abstract
The oxygen content in the arterial system plays a significant role in determining the physiological status of a human body. Understanding the oxygen concentration distribution in the arterial system is beneficial for the prevention and intervention of vascular disease. However, the oxygen concentration in the arteries could not be noninvasively monitored in clinical research. Although the oxygen concentration distribution in a vessel could be obtained from a three-dimensional (3D) numerical simulation of blood flow coupled with oxygen transport, a 3D numerical simulation of the systemic arterial tree is complicated and requires considerable computational resources and time. However, the lumped parameter model of oxygen transport derived from transmission line equations of oxygen transport requires fewer computational resources and less time to numerically predict the oxygen concentration distribution in the systemic arterial tree. In this study, transmission line equations of oxygen transport are developed according to the theory of oxygen transport in the vessel, and fluid transmission line equations are used as the theoretical reference for the development. The transmission line equations of oxygen transport could also be regarded as the theoretical basis for developing lumped parameter models of other substances in blood.
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34
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Hua J, Liu P, Kim T, Donahue M, Rane S, Chen JJ, Qin Q, Kim SG. MRI techniques to measure arterial and venous cerebral blood volume. Neuroimage 2018; 187:17-31. [PMID: 29458187 DOI: 10.1016/j.neuroimage.2018.02.027] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 12/14/2022] Open
Abstract
The measurement of cerebral blood volume (CBV) has been the topic of numerous neuroimaging studies. To date, however, most in vivo imaging approaches can only measure CBV summed over all types of blood vessels, including arterial, capillary and venous vessels in the microvasculature (i.e. total CBV or CBVtot). As different types of blood vessels have intrinsically different anatomy, function and physiology, the ability to quantify CBV in different segments of the microvascular tree may furnish information that is not obtainable from CBVtot, and may provide a more sensitive and specific measure for the underlying physiology. This review attempts to summarize major efforts in the development of MRI techniques to measure arterial (CBVa) and venous CBV (CBVv) separately. Advantages and disadvantages of each type of method are discussed. Applications of some of the methods in the investigation of flow-volume coupling in healthy brains, and in the detection of pathophysiological abnormalities in brain diseases such as arterial steno-occlusive disease, brain tumors, schizophrenia, Huntington's disease, Alzheimer's disease, and hypertension are demonstrated. We believe that the continual development of MRI approaches for the measurement of compartment-specific CBV will likely provide essential imaging tools for the advancement and refinement of our knowledge on the exquisite details of the microvasculature in healthy and diseased brains.
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Affiliation(s)
- Jun Hua
- Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
| | - Peiying Liu
- Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Tae Kim
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Manus Donahue
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Swati Rane
- Radiology, University of Washington Medical Center, Seattle, WA, USA
| | - J Jean Chen
- Rotman Research Institute, Baycrest Centre, Canada; Department of Medical Biophysics, University of Toronto, Canada
| | - Qin Qin
- Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon, South Korea; Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea
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35
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Uhlirova H, Kılıç K, Tian P, Sakadžić S, Gagnon L, Thunemann M, Desjardins M, Saisan PA, Nizar K, Yaseen MA, Hagler DJ, Vandenberghe M, Djurovic S, Andreassen OA, Silva GA, Masliah E, Kleinfeld D, Vinogradov S, Buxton RB, Einevoll GT, Boas DA, Dale AM, Devor A. The roadmap for estimation of cell-type-specific neuronal activity from non-invasive measurements. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0356. [PMID: 27574309 DOI: 10.1098/rstb.2015.0356] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2016] [Indexed: 12/22/2022] Open
Abstract
The computational properties of the human brain arise from an intricate interplay between billions of neurons connected in complex networks. However, our ability to study these networks in healthy human brain is limited by the necessity to use non-invasive technologies. This is in contrast to animal models where a rich, detailed view of cellular-level brain function with cell-type-specific molecular identity has become available due to recent advances in microscopic optical imaging and genetics. Thus, a central challenge facing neuroscience today is leveraging these mechanistic insights from animal studies to accurately draw physiological inferences from non-invasive signals in humans. On the essential path towards this goal is the development of a detailed 'bottom-up' forward model bridging neuronal activity at the level of cell-type-specific populations to non-invasive imaging signals. The general idea is that specific neuronal cell types have identifiable signatures in the way they drive changes in cerebral blood flow, cerebral metabolic rate of O2 (measurable with quantitative functional Magnetic Resonance Imaging), and electrical currents/potentials (measurable with magneto/electroencephalography). This forward model would then provide the 'ground truth' for the development of new tools for tackling the inverse problem-estimation of neuronal activity from multimodal non-invasive imaging data.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
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Affiliation(s)
- Hana Uhlirova
- Department of Radiology, UCSD, La Jolla, CA 92093, USA CEITEC-Central European Institute of Technology and Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic
| | - Kıvılcım Kılıç
- Department of Neurosciences, UCSD, La Jolla, CA 92093, USA
| | - Peifang Tian
- Department of Neurosciences, UCSD, La Jolla, CA 92093, USA Department of Physics, John Carroll University, University Heights, OH 44118, USA
| | - Sava Sakadžić
- Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Charlestown, MA 02129, USA
| | - Louis Gagnon
- Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Charlestown, MA 02129, USA
| | | | | | - Payam A Saisan
- Department of Neurosciences, UCSD, La Jolla, CA 92093, USA
| | - Krystal Nizar
- Neurosciences Graduate Program, UCSD, La Jolla, CA 92093, USA
| | - Mohammad A Yaseen
- Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Charlestown, MA 02129, USA
| | | | - Matthieu Vandenberghe
- Department of Radiology, UCSD, La Jolla, CA 92093, USA NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway
| | - Srdjan Djurovic
- Department of Medical Genetics, Oslo University Hospital, 0407 Oslo, Norway NORMENT, KG Jebsen Centre for Psychosis Research, Department of Clinical Science, University of Bergen, 5020 Bergen, Norway
| | - Ole A Andreassen
- NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway
| | - Gabriel A Silva
- Department of Bioengineering, UCSD, La Jolla, CA 92093, USA Department of Opthalmology, UCSD, La Jolla, CA 92093, USA
| | | | - David Kleinfeld
- Department of Physics, UCSD, La Jolla, CA 92093, USA Department of Electrical and Computer Engineering, UCSD, La Jolla, CA 92093, USA Section of Neurobiology, UCSD, La Jolla, CA 92093, USA
| | - Sergei Vinogradov
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Gaute T Einevoll
- Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, 1432 Ås, Norway Department of Physics, University of Oslo, 0316 Oslo, Norway
| | - David A Boas
- Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Charlestown, MA 02129, USA
| | - Anders M Dale
- Department of Radiology, UCSD, La Jolla, CA 92093, USA Department of Neurosciences, UCSD, La Jolla, CA 92093, USA
| | - Anna Devor
- Department of Radiology, UCSD, La Jolla, CA 92093, USA Department of Neurosciences, UCSD, La Jolla, CA 92093, USA Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Charlestown, MA 02129, USA
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36
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Lacy TC, Aquino KM, Robinson PA, Schira MM. Shock-like haemodynamic responses induced in the primary visual cortex by moving visual stimuli. J R Soc Interface 2017; 13:rsif.2016.0576. [PMID: 27974572 DOI: 10.1098/rsif.2016.0576] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/17/2016] [Indexed: 11/12/2022] Open
Abstract
It is shown that recently discovered haemodynamic waves can form shock-like fronts when driven by stimuli that excite the cortex in a patch that moves faster than the haemodynamic wave velocity. If stimuli are chosen in order to induce shock-like behaviour, the resulting blood oxygen level-dependent (BOLD) response is enhanced, thereby improving the signal to noise ratio of measurements made with functional magnetic resonance imaging. A spatio-temporal haemodynamic model is extended to calculate the BOLD response and determine the main properties of waves induced by moving stimuli. From this, the optimal conditions for stimulating shock-like responses are determined, and ways of inducing these responses in experiments are demonstrated in a pilot study.
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Affiliation(s)
- T C Lacy
- School of Physics, University of Sydney, New South Wales, Australia .,Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia
| | - K M Aquino
- School of Physics, University of Sydney, New South Wales, Australia.,Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia.,Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - P A Robinson
- School of Physics, University of Sydney, New South Wales, Australia.,Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia
| | - M M Schira
- School of Psychology, University of Wollongong, Wollongong, New South Wales 2522, Australia.,Neuroscience Research Australia, Royal Hospital for Women, Randwick, New South Wales 2031, Australia
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37
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Petridou N, Siero JCW. Laminar fMRI: What can the time domain tell us? Neuroimage 2017; 197:761-771. [PMID: 28736308 DOI: 10.1016/j.neuroimage.2017.07.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/06/2017] [Accepted: 07/19/2017] [Indexed: 01/30/2023] Open
Abstract
The rapid developments in functional MRI (fMRI) acquisition methods and hardware technologies in recent years, particularly at high field (≥7 T), have enabled unparalleled visualization of functional detail at a laminar or columnar level, bringing fMRI close to the intrinsic resolution of brain function. These advances highlight the potential of high resolution fMRI to be a valuable tool to study the fundamental processing performed in cortical micro-circuits, and their interactions such as feedforward and feedback processes. Notably, because fMRI measures neuronal activity via hemodynamics, the ultimate resolution it affords depends on the spatial specificity of hemodynamics to neuronal activity at a detailed spatial scale, and by the evolution of this specificity over time. Several laminar (≤1 mm spatial resolution) fMRI studies have examined spatial characteristics of the measured hemodynamic signals across cortical depth, in light of understanding or improving the spatial specificity of laminar fMRI. Few studies have examined temporal features of the hemodynamic response across cortical depth. Temporal features of the hemodynamic response offer an additional means to improve the specificity of fMRI, and could help target neuronal processes and neurovascular coupling relationships across laminae, for example by differences in the onset times of the response across cortical depth. In this review, we discuss factors that affect the timing of neuronal and hemodynamic responses across laminae, touching on the neuronal laminar organization, and focusing on the laminar vascular organization. We provide an overview of hemodynamics across the cortical vascular tree based on optical imaging studies, and review temporal aspects of hemodynamics that have been examined across cortical depth in high spatiotemporal resolution fMRI studies. Last, we discuss the limits and potential of high spatiotemporal resolution fMRI to study laminar neurovascular coupling and neuronal processes.
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Affiliation(s)
- Natalia Petridou
- Radiology, University Medical Centre Utrecht, Utrecht, The Netherlands.
| | - Jeroen C W Siero
- Radiology, University Medical Centre Utrecht, Utrecht, The Netherlands; Spinoza Centre for Neuroimaging, Amsterdam, The Netherlands
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Sauvage A, Hubert G, Touboul J, Ribot J. The hemodynamic signal as a first-order low-pass temporal filter: Evidence and implications for neuroimaging studies. Neuroimage 2017; 155:394-405. [PMID: 28343986 DOI: 10.1016/j.neuroimage.2017.03.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 02/28/2017] [Accepted: 03/23/2017] [Indexed: 01/26/2023] Open
Abstract
Neuronal activation triggers local changes in blood flow and hemoglobin oxygenation. These hemodynamic signals can be recorded through functional magnetic resonance imaging or intrinsic optical imaging, and allows inferring neural activity in response to stimuli. These techniques are widely used to uncover functional brain architectures. However, their accuracy suffers from distortions inherent to hemodynamic responses and noise. The analysis of these signals currently relies on models of impulse hemodynamic responses to brief stimuli. Here, in order to infer precise functional architectures, we focused on integrated signals associated to the dynamic response of functional maps. To this end, we recorded orientation and direction maps in cat primary visual cortex and compared two protocols: the conventional episodic stimulation technique and a continuous, periodic stimulation paradigm. Conventional methods show that the dynamics of activation and deactivation of the functional maps follows a linear first-order differential equation representing a low-pass filter. Comparison with the periodic stimulation methods confirmed this observation: the phase shifts and magnitude attenuations extracted at various frequencies were consistent with a low-pass filter with a 5s time constant. This dynamics presumably reflects the variations in deoxyhemoglobin mediated by arterial dilations. This dynamics open new avenues in the analysis of neuroimaging data that differs from common methods based on the hemodynamic response function. In particular, we demonstrate that inverting this first-order low-pass filter minimized the distortions of the signal and enabled a much faster and accurate reconstruction of functional maps.
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Affiliation(s)
- Antoine Sauvage
- Mathematical Neuroscience Team, CIRB - Collège de France (CNRS UMR 7241, INSERM U1050, UPMC ED 158, MEMOLIFE PSL), 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Guillaume Hubert
- Mathematical Neuroscience Team, CIRB - Collège de France (CNRS UMR 7241, INSERM U1050, UPMC ED 158, MEMOLIFE PSL), 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Jonathan Touboul
- Mathematical Neuroscience Team, CIRB - Collège de France (CNRS UMR 7241, INSERM U1050, UPMC ED 158, MEMOLIFE PSL), 11 Place Marcelin Berthelot, 75005 Paris, France; INRIA Mycenae Team, Paris-Rocquencourt, France
| | - Jérôme Ribot
- Mathematical Neuroscience Team, CIRB - Collège de France (CNRS UMR 7241, INSERM U1050, UPMC ED 158, MEMOLIFE PSL), 11 Place Marcelin Berthelot, 75005 Paris, France.
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Schmid F, Barrett MJP, Jenny P, Weber B. Vascular density and distribution in neocortex. Neuroimage 2017; 197:792-805. [PMID: 28669910 DOI: 10.1016/j.neuroimage.2017.06.046] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/09/2017] [Accepted: 06/20/2017] [Indexed: 12/22/2022] Open
Abstract
An amazingly wide range of complex behavior emerges from the cerebral cortex. Much of the information processing that leads to these behaviors is performed in neocortical circuits that span throughout the six layers of the cortex. Maintaining this circuit activity requires substantial quantities of oxygen and energy substrates, which are delivered by the complex yet well-organized and tightly-regulated vascular system. In this review, we provide a detailed characterization of the most relevant anatomical and functional features of the cortical vasculature. This includes a compilation of the available data on laminar variation of vascular density and the topological aspects of the microvascular system. We also review the spatio-temporal dynamics of cortical blood flow regulation and oxygenation, many aspects of which remain poorly understood. Finally, we discuss some of the important implications of vascular density, distribution, oxygenation and blood flow regulation for (laminar) fMRI.
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Affiliation(s)
- Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland.
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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Liang Y, Jin L, Guan BO, Wang L. 2 MHz multi-wavelength pulsed laser for functional photoacoustic microscopy. OPTICS LETTERS 2017; 42:1452-1455. [PMID: 28362790 DOI: 10.1364/ol.42.001452] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Fast functional photoacoustic microscopy requires multi-wavelength pulsed laser sources with high pulse repetition rates, short wavelength switching time, and sufficient pulse energies. Here, we report the development of a stimulated-Raman-scattering-based multi-wavelength pulsed laser source for fast functional photoacoustic imaging. The new laser source is pumped with a 532 nm 1 MHz pulsed laser. The 532 nm laser beam is split into two: one pumps a 5 m optical fiber to excite a 558 nm wavelength via stimulated Raman scattering; the other goes through a 50 m optical fiber to delay the 532 nm pulse by 220 ns. The two beams are combined and coupled into an optical fiber for photoacoustic excitation. As a result, the new laser source can generate 2 million pulses per second, switch wavelengths in 220 ns, and provide hundreds of nanojoules pulse energy for each wavelength. Using this laser source, we demonstrate optical-resolution photoacoustic imaging of microvascular structures and oxygen saturation in the mouse ear. The ultrashort wavelength switching time enables oxygen saturation imaging of flowing red blood cells, which is valuable for high-resolution functional imaging.
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Ciris PA, Qiu M, Constable RT. Non-invasive quantification of absolute cerebral blood volume during functional activation applicable to the whole human brain. Magn Reson Med 2016; 71:580-90. [PMID: 23475774 DOI: 10.1002/mrm.24694] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PURPOSE Cerebral blood volume (CBV) changes in many diverse pathologic conditions, and in response to functional challenges along with changes in blood flow, blood oxygenation, and the cerebral metabolic rate of oxygen. The feasibility of a new method for non-invasive quantification of absolute cerebral blood volume that can be applicable to the whole human brain was investigated. METHODS Multi-slice data were acquired at 3 T using a novel inversion recovery echo planar imaging (IR-EPI) pulse sequence with varying contrast weightings and an efficient rotating slice acquisition order, at rest and during visual activation. A biophysical model was used to estimate absolute cerebral blood volume at rest and during activation, and oxygenation during activation, on data from 13 normal human subjects. RESULTS Cerebral blood volume increased by 21.7% from 6.6 ± 0.8 mL/100 mL of brain parenchyma at rest to 8.0 ± 1.3 mL/100 mL of brain parenchyma in the occipital cortex during visual activation, with average blood oxygenation of 84 ± 2.1% during activation, comparing well with literature. CONCLUSION The method is feasible, and could foster improved understanding of the fundamental physiological relationship between neuronal activity, hemodynamic changes, and metabolism underlying brain activation; complement existing methods for estimating compartmental changes; and potentially find utility in evaluating vascular health.
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Affiliation(s)
- Pelin Aksit Ciris
- Department of Biomedical Engineering, Yale University, School of Medicine, Magnetic Resonance Research Center, New Haven, Connecticut, USA
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42
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Lee S, Kang BM, Shin MK, Min J, Heo C, Lee Y, Baeg E, Suh M. Chronic Stress Decreases Cerebrovascular Responses During Rat Hindlimb Electrical Stimulation. Front Neurosci 2015; 9:462. [PMID: 26778944 PMCID: PMC4688360 DOI: 10.3389/fnins.2015.00462] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 11/23/2015] [Indexed: 12/21/2022] Open
Abstract
Repeated stress is one of the major risk factors for cerebrovascular disease, including stroke, and vascular dementia. However, the functional alterations in the cerebral hemodynamic response induced by chronic stress have not been clarified. Here, we investigated the in vivo cerebral hemodynamic changes and accompanying cellular and molecular changes in chronically stressed rats. After 3 weeks of restraint stress, the elicitation of stress was verified by behavioral despair in the forced swimming test and by physical indicators of stress. The evoked changes in the cerebral blood volume and pial artery responses following hindpaw electrical stimulation were measured using optical intrinsic signal imaging. We observed that, compared to the control group, animals under chronic restraint stress exhibited a decreased hemodynamic response, with a smaller pial arterial dilation in the somatosensory cortex during hindpaw electrical stimulation. The effect of chronic restraint stress on vasomodulator enzymes, including neuronal nitric oxide synthase (nNOS) and heme oxygenase-2 (HO-2), was assessed in the somatosensory cortex. Chronic restraint stress downregulated nNOS and HO-2 compared to the control group. In addition, we examined the subtypes of cells that can explain the environmental changes due to the decreased vasomodulators. The expression of parvalbumin in GABAergic interneurons and glutamate receptor-1 in neurons were decreased, whereas the microglial activation was increased. Our results suggest that the chronic stress-induced alterations in cerebral vascular function and the modulations of the cellular expression in the neuro-vasomodulatory system may be crucial contributing factors in the development of various vascular-induced conditions in the brain.
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Affiliation(s)
- Sohee Lee
- Center for Neuroscience Imaging Research, Institute for Basic Science Suwon, South Korea
| | - Bok-Man Kang
- Center for Neuroscience Imaging Research, Institute for Basic Science Suwon, South Korea
| | - Min-Kyoo Shin
- Department of Biological Science, Sungkyunkwan University Suwon, South Korea
| | - Jiwoong Min
- Department of Biomedical Engineering, Sungkyunkwan University Suwon, South Korea
| | - Chaejeong Heo
- Center for Neuroscience Imaging Research, Institute for Basic Science Suwon, South Korea
| | - Yubu Lee
- Center for Neuroscience Imaging Research, Institute for Basic Science Suwon, South Korea
| | - Eunha Baeg
- Center for Neuroscience Imaging Research, Institute for Basic Science Suwon, South Korea
| | - Minah Suh
- Center for Neuroscience Imaging Research, Institute for Basic ScienceSuwon, South Korea; Department of Biological Science, Sungkyunkwan UniversitySuwon, South Korea; Department of Biomedical Engineering, Sungkyunkwan UniversitySuwon, South Korea; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan UniversitySeoul, South Korea
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Kim JH, Ress D. Arterial impulse model for the BOLD response to brief neural activation. Neuroimage 2015; 124:394-408. [PMID: 26363350 DOI: 10.1016/j.neuroimage.2015.08.068] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/21/2015] [Accepted: 08/31/2015] [Indexed: 12/19/2022] Open
Abstract
The blood oxygen level dependent (BOLD) signal evoked by brief neural stimulation, the hemodynamic response function (HRF), is a critical feature of neurovascular coupling. The HRF is directly related to local transient changes in oxygen supplied by cerebral blood flow (CBF) and oxygen demand, the cerebral metabolic rate of oxygen (CMRO2). Previous efforts to explain the HRF have relied upon the hypothesis that CBF produces a non-linear venous dilation within the cortical parenchyma. Instead, the observed dynamics correspond to prompt arterial dilation without venous volume change. This work develops an alternative biomechanical model for the BOLD response based on the hypothesis that prompt upstream dilation creates an arterial flow impulse amenable to linear description. This flow model is coupled to a continuum description of oxygen transport. Measurements using high-resolution fMRI demonstrate the efficacy of the model. The model predicts substantial spatial variations of the oxygen saturation along the length of capillaries and veins, and fits the varied gamut of measured HRFs by the combined effects of corresponding CBF and CMRO2 responses. Three interesting relationships among the hemodynamic parameters are predicted. First, there is an offset linear correlation with approximately unity slope between CBF and CMRO2 responses. Second, the HRF undershoot is strongly correlated to the corresponding CBF undershoot. Third, late-time-CMRO2 response can contribute to a slow recovery to baseline, lengthening the HRF undershoot. The model provides a powerful mathematical framework to understand the dynamics of neurovascular and neurometabolic responses that form the BOLD HRF.
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Affiliation(s)
- Jung Hwan Kim
- Department of Neuroscience, Core for Advanced MR Imaging, Baylor College of Medicine, Houston, TX 77030, USA
| | - David Ress
- Department of Neuroscience, Core for Advanced MR Imaging, Baylor College of Medicine, Houston, TX 77030, USA.
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Schmid S, Teeuwisse WM, Lu H, van Osch MJP. Time-efficient determination of spin compartments by time-encoded pCASL T2-relaxation-under-spin-tagging and its application in hemodynamic characterization of the cerebral border zones. Neuroimage 2015; 123:72-9. [PMID: 26297847 DOI: 10.1016/j.neuroimage.2015.08.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/31/2015] [Accepted: 08/11/2015] [Indexed: 11/19/2022] Open
Abstract
Information on water-transport across the blood-brain barrier can be determined from the T2 of the arterial spin labeling (ASL) signal. However, the current approach of using separate acquisitions of multiple inversion times is too time-consuming for clinical (research) applications. The aim of this study was to improve the time-efficiency of this method by combining it with time-encoded pseudo-continuous ASL (te-pCASL). Furthermore, the hemodynamic properties of the border zone regions in the brains of healthy, young volunteers were characterized as an example application. The use of te-pCASL instead of multi-TI pCASL significantly reduced the total scan duration, while providing a higher temporal resolution. A significantly lower cerebral blood flow (CBF) was found in the border zone regions compared with the central regions in both the posterior and the middle cerebral artery (MCA) flow territory. The arterial transit time (ATT) was almost two times longer in the border zone regions than in the central regions (p<0.05), with an average delay in ATT of 382ms in the posterior and 539ms in the MCA flow territory. When corrected for the ATT, the change in T2 over time was not significantly different for the border zones as compared to the central regions. In conclusion, te-pCASL-TRUST provided a time-efficient method to distinguish spin compartments based on their T2. The ATT in the border zone is significantly longer than in the central region. However, the exchange of the label from the arterial to the tissue compartment appears to be at a similar rate.
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Affiliation(s)
- Sophie Schmid
- C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
| | - Wouter M Teeuwisse
- C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Leiden, The Netherlands; Leiden Institute for Brain and Cognition, Leiden, The Netherlands.
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University, Baltimore, United States.
| | - Matthias J P van Osch
- C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Leiden, The Netherlands; Leiden Institute for Brain and Cognition, Leiden, The Netherlands.
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45
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Chong SP, Merkle CW, Leahy C, Radhakrishnan H, Srinivasan VJ. Quantitative microvascular hemoglobin mapping using visible light spectroscopic Optical Coherence Tomography. BIOMEDICAL OPTICS EXPRESS 2015; 6:1429-50. [PMID: 25909026 PMCID: PMC4399681 DOI: 10.1364/boe.6.001429] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 02/19/2015] [Accepted: 03/14/2015] [Indexed: 05/18/2023]
Abstract
Quantification of chromophore concentrations in reflectance mode remains a major challenge for biomedical optics. Spectroscopic Optical Coherence Tomography (SOCT) provides depth-resolved spectroscopic information necessary for quantitative analysis of chromophores, like hemoglobin, but conventional SOCT analysis methods are applicable only to well-defined specular reflections, which may be absent in highly scattering biological tissue. Here, by fitting of the dynamic scattering signal spectrum in the OCT angiogram using a forward model of light propagation, we quantitatively determine hemoglobin concentrations directly. Importantly, this methodology enables mapping of both oxygen saturation and total hemoglobin concentration, or alternatively, oxyhemoglobin and deoxyhemoglobin concentration, simultaneously. Quantification was verified by ex vivo blood measurements at various pO2 and hematocrit levels. Imaging results from the rodent brain and retina are presented. Confounds including noise and scattering, as well as potential clinical applications, are discussed.
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Rasmussen PM, Jespersen SN, Østergaard L. The effects of transit time heterogeneity on brain oxygenation during rest and functional activation. J Cereb Blood Flow Metab 2015; 35:432-42. [PMID: 25492112 PMCID: PMC4348381 DOI: 10.1038/jcbfm.2014.213] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 10/20/2014] [Accepted: 11/03/2014] [Indexed: 12/15/2022]
Abstract
The interpretation of regional blood flow and blood oxygenation changes during functional activation has evolved from the concept of 'neurovascular coupling', and hence the regulation of arteriolar tone to meet metabolic demands. The efficacy of oxygen extraction was recently shown to depend on the heterogeneity of capillary flow patterns downstream. Existing compartment models of the relation between tissue metabolism, blood flow, and blood oxygenation, however, typically assume homogenous microvascular flow patterns. To take capillary flow heterogeneity into account, we modeled the effect of capillary transit time heterogeneity (CTH) on the 'oxygen conductance' used in compartment models. We show that the incorporation of realistic reductions in CTH during functional hyperemia improves model fits to dynamic blood flow and oxygenation changes acquired during functional activation in a literature animal study. Our results support earlier observations that oxygen diffusion properties seemingly change during various physiologic stimuli, and posit that this phenomenon is related to parallel changes in capillary flow patterns. Furthermore, our results suggest that CTH must be taken into account when inferring brain metabolism from changes in blood flow- or blood oxygenation-based signals .
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Affiliation(s)
- Peter M Rasmussen
- Department of Clinical Medicine, Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University Hospital, Aarhus, Denmark
| | - Sune N Jespersen
- 1] Department of Clinical Medicine, Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University Hospital, Aarhus, Denmark [2] Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Leif Østergaard
- 1] Department of Clinical Medicine, Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University Hospital, Aarhus, Denmark [2] Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark
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Barrett MJ, Suresh V. Improving estimates of the cerebral metabolic rate of oxygen from optical imaging data. Neuroimage 2015; 106:101-10. [DOI: 10.1016/j.neuroimage.2014.11.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/27/2014] [Accepted: 11/18/2014] [Indexed: 01/26/2023] Open
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Functional Imaging of Cerebral Oxygenation with Intrinsic Optical Contrast and Phosphorescent Probes. NEUROMETHODS 2014. [DOI: 10.1007/978-1-62703-785-3_14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Ciris PA, Qiu M, Constable RT. Noninvasive MRI measurement of the absolute cerebral blood volume-cerebral blood flow relationship during visual stimulation in healthy humans. Magn Reson Med 2013; 72:864-75. [PMID: 24151246 DOI: 10.1002/mrm.24984] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/12/2013] [Accepted: 09/13/2013] [Indexed: 01/02/2023]
Abstract
PURPOSE The relationship between cerebral blood volume (CBV) and cerebral blood flow (CBF) underlies blood oxygenation level-dependent functional MRI signal. This study investigates the potential for improved characterization of the CBV-CBF relationship in humans, and examines sex effects as well as spatial variations in the CBV-CBF relationship. METHODS Healthy subjects were imaged noninvasively at rest and during visual stimulation, constituting the first MRI measurement of the absolute CBV-CBF relationship in humans with complete coverage of the functional areas of interest. RESULTS CBV and CBF estimates were consistent with the literature, and their relationship varied both spatially and with sex. In a region of interest with stimulus-induced activation in CBV and CBF at a significance level of the P < 0.05, a power function fit resulted in CBV = 2.1 CBF(0.32) across all subjects, CBV = 0.8 CBF(0.51) in females and CBV = 4.4 CBF(0.15) in males. Exponents decreased in both sexes as ROIs were expanded to include less significantly activated regions. CONCLUSION Consideration for potential sex-related differences, as well as regional variations under a range of physiological states, may reconcile some of the variation across literature and advance our understanding of the underlying cerebrovascular physiology.
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Affiliation(s)
- Pelin Aksit Ciris
- Department of Biomedical Engineering, Yale University, School of Medicine, Magnetic Resonance Research Center, New Haven, Connecticut, USA
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50
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Kim JH, Khan R, Thompson JK, Ress D. Model of the transient neurovascular response based on prompt arterial dilation. J Cereb Blood Flow Metab 2013; 33:1429-39. [PMID: 23756690 PMCID: PMC3764388 DOI: 10.1038/jcbfm.2013.90] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 04/30/2013] [Accepted: 05/13/2013] [Indexed: 01/02/2023]
Abstract
Brief neural stimulation results in a stereotypical pattern of vascular and metabolic response that is the basis for popular brain-imaging methods such as functional magnetic resonance imagine. However, the mechanisms of transient oxygen transport and its coupling to cerebral blood flow (CBF) and oxygen metabolism (CMRO2) are poorly understood. Recent experiments show that brief stimulation produces prompt arterial vasodilation rather than venous vasodilation. This work provides a neurovascular response model for brief stimulation based on transient arterial effects using one-dimensional convection-diffusion transport. Hemoglobin oxygen dissociation is included to enable predictions of absolute oxygen concentrations. Arterial CBF response is modeled using a lumped linear flow model, and CMRO2 response is modeled using a gamma function. Using six parameters, the model successfully fit 161/166 measured extravascular oxygen time courses obtained for brief visual stimulation in cat cerebral cortex. Results show how CBF and CMRO2 responses compete to produce the observed features of the hemodynamic response: initial dip, hyperoxic peak, undershoot, and ringing. Predicted CBF and CMRO2 response amplitudes are consistent with experimental measurements. This model provides a powerful framework to quantitatively interpret oxygen transport in the brain; in particular, its intravascular oxygen concentration predictions provide a new model for fMRI responses.
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Affiliation(s)
- Jung Hwan Kim
- Section of Neurobiology and Imaging Research Center, The University of Texas at Austin, Austin, TX, USA
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