101
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Zhou H, Arias-Ramos N, López-Larrubia P, Mason RP, Cerdán S, Pacheco-Torres J. Oxygenation Imaging by Nuclear Magnetic Resonance Methods. Methods Mol Biol 2018; 1718:297-313. [PMID: 29341016 DOI: 10.1007/978-1-4939-7531-0_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Oxygen monitoring is a topic of exhaustive research due to its central role in many biological processes, from energy metabolism to gene regulation. The ability to monitor in vivo the physiological distribution and the dynamics of oxygen from subcellular to macroscopic levels is a prerequisite to better understand the mechanisms associated with both normal and disease states (cancer, neurodegeneration, stroke, etc.). This chapter focuses on magnetic resonance imaging (MRI) based techniques to assess oxygenation in vivo. The first methodology uses injected fluorinated agents to provide quantitative pO2 measurements with high precision and suitable spatial and temporal resolution for many applications. The second method exploits changes in endogenous contrasts, i.e., deoxyhemoglobin and oxygen molecules through measurements of T 2* and T 1, in response to an intervention to qualitatively evaluate hypoxia and its potential modulation.
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Affiliation(s)
- Heling Zhou
- Prognostic Imaging Research Laboratory, Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Nuria Arias-Ramos
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica de Biociències, Edifici Cs, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | - Pilar López-Larrubia
- Instituto de Investigaciones Biomédicas 'Alberto Sols' C.S.I.C./U.A.M., Madrid, Spain
| | - Ralph P Mason
- Prognostic Imaging Research Laboratory, Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sebastián Cerdán
- Instituto de Investigaciones Biomédicas 'Alberto Sols' C.S.I.C./U.A.M., Madrid, Spain
| | - Jesús Pacheco-Torres
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain.
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102
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Albers F, Schmid F, Wachsmuth L, Faber C. Line scanning fMRI reveals earlier onset of optogenetically evoked BOLD response in rat somatosensory cortex as compared to sensory stimulation. Neuroimage 2018; 164:144-154. [DOI: 10.1016/j.neuroimage.2016.12.059] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/17/2016] [Accepted: 12/20/2016] [Indexed: 12/20/2022] Open
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103
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Cudmore RH, Dougherty SE, Linden DJ. Cerebral vascular structure in the motor cortex of adult mice is stable and is not altered by voluntary exercise. J Cereb Blood Flow Metab 2017; 37:3725-3743. [PMID: 28059584 PMCID: PMC5718320 DOI: 10.1177/0271678x16682508] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 10/24/2016] [Accepted: 10/30/2016] [Indexed: 01/09/2023]
Abstract
The cerebral vasculature provides blood flow throughout the brain, and local changes in blood flow are regulated to match the metabolic demands of the active brain regions. This neurovascular coupling is mediated by real-time changes in vessel diameter and depends on the underlying vascular network structure. Neurovascular structure is configured during development by genetic and activity-dependent factors. In adulthood, it can be altered by experiences such as prolonged hypoxia, sensory deprivation and seizure. Here, we have sought to determine whether exercise could alter cerebral vascular structure in the adult mouse. We performed repeated in vivo two-photon imaging in the motor cortex of adult transgenic mice expressing membrane-anchored green fluorescent protein in endothelial cells (tyrosine endothelial kinase 2 receptor (Tie2)-Cre:mTmG). This strategy allows for high-resolution imaging of the vessel walls throughout the lifespan. Vascular structure, as measured by capillary branch point number and position, segment diameter and length remained stable over a time scale of months as did pericyte number and position. Furthermore, we compared the vascular structure before, during, and after periods of voluntary wheel running and found no alterations in these same parameters. In both running and control mice, we observed a low rate of capillary segment subtraction. Interestingly, these rare subtraction events preferentially remove short vascular loops.
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Affiliation(s)
- Robert H Cudmore
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sarah E Dougherty
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J Linden
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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104
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Functional networks and network perturbations in rodents. Neuroimage 2017; 163:419-436. [DOI: 10.1016/j.neuroimage.2017.09.038] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/15/2017] [Accepted: 09/19/2017] [Indexed: 11/16/2022] Open
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105
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Sonnay S, Poirot J, Just N, Clerc AC, Gruetter R, Rainer G, Duarte JMN. Astrocytic and neuronal oxidative metabolism are coupled to the rate of glutamate-glutamine cycle in the tree shrew visual cortex. Glia 2017; 66:477-491. [DOI: 10.1002/glia.23259] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/20/2017] [Accepted: 10/24/2017] [Indexed: 01/09/2023]
Affiliation(s)
- Sarah Sonnay
- Laboratory for Functional and Metabolic Imaging (LIFMET); Ecole Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
| | - Jordan Poirot
- Department of Medicine, Visual Cognition Laboratory; University of Fribourg; Fribourg Switzerland
| | | | - Anne-Catherine Clerc
- Laboratory for Functional and Metabolic Imaging (LIFMET); Ecole Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging (LIFMET); Ecole Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology; University de Lausanne; Lausanne Switzerland
- Department of Radiology; University de Geneva; Geneva Switzerland
| | - Gregor Rainer
- Department of Medicine, Visual Cognition Laboratory; University of Fribourg; Fribourg Switzerland
| | - João M. N. Duarte
- Laboratory for Functional and Metabolic Imaging (LIFMET); Ecole Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Experimental Medical Science, Faculty of Medicine; Lund University; Lund Sweden
- Wallenberg Centre for Molecular Medicine, Lund University; Lund Sweden
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106
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Summers PM, Hartmann DA, Hui ES, Nie X, Deardorff RL, McKinnon ET, Helpern JA, Jensen JH, Shih AY. Functional deficits induced by cortical microinfarcts. J Cereb Blood Flow Metab 2017; 37:3599-3614. [PMID: 28090802 PMCID: PMC5669342 DOI: 10.1177/0271678x16685573] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Clinical studies have revealed a strong link between increased burden of cerebral microinfarcts and risk for cognitive impairment. Since the sum of tissue damage incurred by microinfarcts is a miniscule percentage of total brain volume, we hypothesized that microinfarcts disrupt brain function beyond the injury site visible to histological or radiological examination. We tested this idea using a mouse model of microinfarcts, where single penetrating vessels that supply mouse cortex were occluded by targeted photothrombosis. We found that in vivo structural and diffusion MRI reliably reported the acute microinfarct core, based on spatial co-registrations with post-mortem stains of neuronal viability. Consistent with our hypothesis, c-Fos assays for neuronal activity and in vivo imaging of single vessel hemodynamics both reported functional deficits in viable peri-lesional tissues beyond the microinfarct core. We estimated that the volume of tissue with functional deficit in cortex was at least 12-fold greater than the volume of the microinfarct core. Impaired hemodynamic responses in peri-lesional tissues persisted at least 14 days, and were attributed to lasting deficits in neuronal circuitry or neurovascular coupling. These data show how individually miniscule microinfarcts could contribute to broader brain dysfunction during vascular cognitive impairment and dementia.
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Affiliation(s)
- Philipp M Summers
- 1 Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA
| | - David A Hartmann
- 1 Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA
| | - Edward S Hui
- 2 Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong
| | - Xingju Nie
- 3 Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.,4 Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
| | - Rachael L Deardorff
- 3 Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.,4 Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
| | - Emilie T McKinnon
- 3 Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.,4 Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
| | - Joseph A Helpern
- 1 Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA.,3 Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.,4 Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
| | - Jens H Jensen
- 3 Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.,4 Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
| | - Andy Y Shih
- 1 Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA.,4 Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
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107
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Xi L, Jin T, Zhou J, Carney P, Jiang H. Hybrid photoacoustic and electrophysiological recording of neurovascular communications in freely-moving rats. Neuroimage 2017; 161:232-240. [DOI: 10.1016/j.neuroimage.2017.08.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 07/06/2017] [Accepted: 08/12/2017] [Indexed: 01/06/2023] Open
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108
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Blanco I, Zirak P, Dragojević T, Castellvi C, Durduran T, Justicia C. Longitudinal, transcranial measurement of functional activation in the rat brain by diffuse correlation spectroscopy. NEUROPHOTONICS 2017; 4:045006. [PMID: 29226175 PMCID: PMC5715584 DOI: 10.1117/1.nph.4.4.045006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/09/2017] [Indexed: 05/16/2023]
Abstract
Neural activity is an important biomarker for the presence of neurodegenerative diseases, cerebrovascular alterations, and brain trauma; furthermore, it is a surrogate marker for treatment effects. These pathologies may occur and evolve in a long time-period, thus, noninvasive, transcutaneous techniques are necessary to allow a longitudinal follow-up. In the present work, we have customized noninvasive, transcutaneous, diffuse correlation spectroscopy (DCS) to localize changes in cerebral blood flow (CBF) induced by neural activity. We were able to detect changes in CBF in the somatosensory cortex by using a model of electrical forepaw stimulation in rats. The suitability of DCS measurements for longitudinal monitoring was demonstrated by performing multiple sessions with the same animals at different ages (from 6 to 18 months). In addition, functional DCS has been cross-validated by comparison with functional magnetic resonance imaging (fMRI) in the same animals in a subset of the time-points. The overall results obtained with transcutaneous DCS demonstrates that it can be utilized in longitudinal studies safely and reproducibly to locate changes in CBF induced by neural activity in the small animal brain.
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Affiliation(s)
- Igor Blanco
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
- Address all correspondence to: Igor Blanco, E-mail:
| | - Peyman Zirak
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | - Tanja Dragojević
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | - Clara Castellvi
- Insitut d’Investigacions Biomèdiques de Barcelona (IIBB), Consejo Superior de Investigaciones Científicas (CSIC), Department of Brain Ischemia and Neurodegeneration, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Àrea de Neurociències, Barcelona, Spain
| | - Turgut Durduran
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Carles Justicia
- Insitut d’Investigacions Biomèdiques de Barcelona (IIBB), Consejo Superior de Investigaciones Científicas (CSIC), Department of Brain Ischemia and Neurodegeneration, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Àrea de Neurociències, Barcelona, Spain
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109
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Paasonen J, Salo RA, Ihalainen J, Leikas JV, Savolainen K, Lehtonen M, Forsberg MM, Gröhn O. Dose-response effect of acute phencyclidine on functional connectivity and dopamine levels, and their association with schizophrenia-like symptom classes in rat. Neuropharmacology 2017; 119:15-25. [DOI: 10.1016/j.neuropharm.2017.03.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/31/2017] [Accepted: 03/20/2017] [Indexed: 10/19/2022]
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110
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Sonnay S, Gruetter R, Duarte JMN. How Energy Metabolism Supports Cerebral Function: Insights from 13C Magnetic Resonance Studies In vivo. Front Neurosci 2017; 11:288. [PMID: 28603480 PMCID: PMC5445183 DOI: 10.3389/fnins.2017.00288] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/04/2017] [Indexed: 12/25/2022] Open
Abstract
Cerebral function is associated with exceptionally high metabolic activity, and requires continuous supply of oxygen and nutrients from the blood stream. Since the mid-twentieth century the idea that brain energy metabolism is coupled to neuronal activity has emerged, and a number of studies supported this hypothesis. Moreover, brain energy metabolism was demonstrated to be compartmentalized in neurons and astrocytes, and astrocytic glycolysis was proposed to serve the energetic demands of glutamatergic activity. Shedding light on the role of astrocytes in brain metabolism, the earlier picture of astrocytes being restricted to a scaffold-associated function in the brain is now out of date. With the development and optimization of non-invasive techniques, such as nuclear magnetic resonance spectroscopy (MRS), several groups have worked on assessing cerebral metabolism in vivo. In this context, 1H MRS has allowed the measurements of energy metabolism-related compounds, whose concentrations can vary under different brain activation states. 1H-[13C] MRS, i.e., indirect detection of signals from 13C-coupled 1H, together with infusion of 13C-enriched glucose has provided insights into the coupling between neurotransmission and glucose oxidation. Although these techniques tackle the coupling between neuronal activity and metabolism, they lack chemical specificity and fail in providing information on neuronal and glial metabolic pathways underlying those processes. Currently, the improvement of detection modalities (i.e., direct detection of 13C isotopomers), the progress in building adequate mathematical models along with the increase in magnetic field strength now available render possible detailed compartmentalized metabolic flux characterization. In particular, direct 13C MRS offers more detailed dataset acquisitions and provides information on metabolic interactions between neurons and astrocytes, and their role in supporting neurotransmission. Here, we review state-of-the-art MR methods to study brain function and metabolism in vivo, and their contribution to the current understanding of how astrocytic energy metabolism supports glutamatergic activity and cerebral function. In this context, recent data suggests that astrocytic metabolism has been underestimated. Namely, the rate of oxidative metabolism in astrocytes is about half of that in neurons, and it can increase as much as the rate of neuronal metabolism in response to sensory stimulation.
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Affiliation(s)
- Sarah Sonnay
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland.,Department of Radiology, University of LausanneLausanne, Switzerland.,Department of Radiology, University of GenevaGeneva, Switzerland
| | - João M N Duarte
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland
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111
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Houben T, Loonen IC, Baca SM, Schenke M, Meijer JH, Ferrari MD, Terwindt GM, Voskuyl RA, Charles A, van den Maagdenberg AM, Tolner EA. Optogenetic induction of cortical spreading depression in anesthetized and freely behaving mice. J Cereb Blood Flow Metab 2017; 37:1641-1655. [PMID: 27107026 PMCID: PMC5435281 DOI: 10.1177/0271678x16645113] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cortical spreading depression, which plays an important role in multiple neurological disorders, has been studied primarily with experimental models that use highly invasive methods. We developed a relatively non-invasive optogenetic model to induce cortical spreading depression by transcranial stimulation of channelrhodopsin-2 ion channels expressed in cortical layer 5 neurons. Light-evoked cortical spreading depression in anesthetized and freely behaving mice was studied with intracortical DC-potentials, multi-unit activity and/or non-invasive laser Doppler flowmetry, and optical intrinsic signal imaging. In anesthetized mice, cortical spreading depression induction thresholds and propagation rates were similar for invasive (DC-potential) and non-invasive (laser Doppler flowmetry) recording paradigms. Cortical spreading depression-related vascular and parenchymal optical intrinsic signal changes were similar to those evoked with KCl. In freely behaving mice, DC-potential and multi-unit activity recordings combined with laser Doppler flowmetry revealed cortical spreading depression characteristics comparable to those under anesthesia, except for a shorter cortical spreading depression duration. Cortical spreading depression resulted in a short increase followed by prolonged reduction of spontaneous active behavior. Motor function, as assessed by wire grip tests, was transiently and unilaterally suppressed following a cortical spreading depression. Optogenetic cortical spreading depression induction has significant advantages over current models in that multiple cortical spreading depression events can be elicited in a non-invasive and cell type-selective fashion.
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Affiliation(s)
- Thijs Houben
- 1 Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Inge Cm Loonen
- 2 Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Serapio M Baca
- 3 Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - Maarten Schenke
- 2 Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Johanna H Meijer
- 4 Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Michel D Ferrari
- 1 Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Gisela M Terwindt
- 1 Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rob A Voskuyl
- 2 Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew Charles
- 3 Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - Arn Mjm van den Maagdenberg
- 1 Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.,2 Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Else A Tolner
- 1 Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.,2 Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
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112
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Sonnay S, Duarte JMN, Just N, Gruetter R. Energy metabolism in the rat cortex under thiopental anaesthesia measured In Vivo by 13 C MRS. J Neurosci Res 2017; 95:2297-2306. [PMID: 28316083 DOI: 10.1002/jnr.24032] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 01/05/2017] [Accepted: 01/16/2017] [Indexed: 01/05/2023]
Abstract
Barbiturates, commonly used as general anaesthetics, depress neuronal activity and thus cerebral metabolism. Moreover, they are likely to disrupt the metabolic support of astrocytes to neurons, as well as the uptake of nutrients from circulation. By employing 13 C magnetic resonance spectroscopy (MRS) in vivo at high magnetic field, we characterized neuronal and astrocytic pathways of energy metabolism in the rat cortex under thiopental anaesthesia. The neuronal tricarboxylic acid (TCA) cycle rate was 0.46 ± 0.02 µmol/g/min, and the rate of the glutamate-glutamine cycle was 0.09 ± 0.02 µmol/g/min. In astrocytes, the TCA cycle rate was 0.16 ± 0.02 µmol/g/min, accounting for a quarter of whole brain glucose oxidation, pyruvate carboxylase rate was 0.02 ± 0.01 µmol/g/min, and glutamine synthetase was 0.12 ± 0.01 µmol/g/min. Relative to previous experiments under light α-chloralose anaesthesia, thiopental reduced oxidative metabolism in neurons and even more so in astrocytes. Interestingly, total oxidative metabolism in the cortex under thiopental anaesthesia surpassed the rate of pyruvate production by glycolysis, indicating substantial utilisation of substrates other than glucose, likely plasma lactate. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Sarah Sonnay
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale Lausanne, Switzerland
| | - João M N Duarte
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale Lausanne, Switzerland
| | - Nathalie Just
- Centre d'Imagerie Biomédicale - Animal and Technology Core, Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale Lausanne, Switzerland.,Department of Radiology, University of Geneva, Switzerland.,Department of Radiology, University of Lausanne, Switzerland
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113
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Bimpisidis Z, Öberg CM, Maslava N, Cenci MA, Lundblad C. Differential effects of gaseous versus injectable anesthetics on changes in regional cerebral blood flow and metabolism induced by l-DOPA in a rat model of Parkinson's disease. Exp Neurol 2017; 292:113-124. [PMID: 28284817 DOI: 10.1016/j.expneurol.2017.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/06/2017] [Accepted: 03/07/2017] [Indexed: 01/03/2023]
Abstract
Preclinical imaging of brain activity requires the use of anesthesia. In this study, we have compared the effects of two widely used anesthetics, inhaled isoflurane and ketamine/xylazine cocktail, on cerebral blood flow and metabolism in a rat model of Parkinson's disease and l-DOPA-induced dyskinesia. Specific tracers were used to estimate regional cerebral blood flow (rCBF - [14C]-iodoantipyrine) and regional cerebral metabolic rate (rCMR - [14C]-2-deoxyglucose) with a highly sensitive autoradiographic method. The two types of anesthetics had quite distinct effects on l-DOPA-induced changes in rCBF and rCMR. Isoflurane did not affect either the absolute rCBF values or the increases in rCBF in the basal ganglia after l-DOPA administration. On the contrary, rats anesthetized with ketamine/xylazine showed lower absolute rCBF values, and the rCBF increases induced by l-DOPA were masked. We developed a novel improved model to calculate rCMR, and found lower metabolic activities in rats anesthetized with isoflurane compared to animals anesthetized with ketamine/xylazine. Both anesthetics prevented changes in rCMR upon l-DOPA administration. Pharmacological challenges in isoflurane-anesthetized rats indicated that drugs mimicking the actions of ketamine/xylazine on adrenergic or glutamate receptors reproduced distinct effects of the injectable anesthetics on rCBF and rCMR. Our results highlight the importance of anesthesia in studies of cerebral flow and metabolism, and provide novel insights into mechanisms mediating abnormal neurovascular responses to l-DOPA in Parkinson's disease.
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Affiliation(s)
- Zisis Bimpisidis
- Basal Ganglia Pathophysiology Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden.
| | - Carl M Öberg
- Department of Clinical Sciences, Nephrology, Lund University, Lund, Sweden
| | - Natallia Maslava
- Basal Ganglia Pathophysiology Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - M Angela Cenci
- Basal Ganglia Pathophysiology Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden.
| | - Cornelia Lundblad
- Anesthesiology and Intensive Care, Department of Clinical Medical Science, Lund University, Lund, Sweden
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114
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Investigation of optical neuro-monitoring technique for detection of maintenance and emergence states during general anesthesia. J Clin Monit Comput 2017; 32:147-163. [PMID: 28214930 DOI: 10.1007/s10877-017-9998-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 01/31/2017] [Indexed: 10/20/2022]
Abstract
The American Society of Anesthesiologist recommends peripheral physiological monitoring during general anesthesia, which offers no information regarding the effects of anesthetics on the brain. Since no "gold standard" method exists for this evaluation, such a technique is needed to ensure patient comfort, procedure quality and safety. In this study we investigated functional near infrared spectroscopy (fNIRS) as possible monitor of anesthetic effects on the prefrontal cortex. Anesthetic drugs, such as sevoflurane, suppress the cerebral metabolism and alter the cerebral blood flow. We hypothesize that fNIRS derived features carry information on the effects of anesthetics on the prefrontal cortex (PFC) that can be used for the classification of the anesthetized state. In this study, patients were continuously monitored using fNIRS, BIS and standard monitoring during surgical procedures under sevoflurane general anesthesia. Maintenance and emergence states were identified and fNIRS features were identified and compared between states. Linear and non-linear machine learning algorithms were investigated as methods for the classification of maintenance/emergence. The results show that changes in oxygenated (HbO2) and deoxygenated hemoglobin (HHb) concentration and blood volume measured by fNIRS were associated with the transition between maintenance and emergence that occurs as a result of sevoflurane washout. We observed that during maintenance the signal is relatively more stable than during emergence. Maintenance and emergence states were classified with 94.7% accuracy with a non-linear model using the locally derived mean total hemoglobin, standard deviation of HbO2, minimum and range of HbO2 and HHb as features. These features were found to be correlated with the effects of sevoflurane and to carry information that allows real time and automatic classification of the anesthetized state with high accuracy.
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115
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Lecrux C, Sandoe CH, Neupane S, Kropf P, Toussay X, Tong XK, Lacalle-Aurioles M, Shmuel A, Hamel E. Impact of Altered Cholinergic Tones on the Neurovascular Coupling Response to Whisker Stimulation. J Neurosci 2017; 37:1518-1531. [PMID: 28069927 PMCID: PMC6705676 DOI: 10.1523/jneurosci.1784-16.2016] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 12/22/2016] [Accepted: 12/30/2016] [Indexed: 11/21/2022] Open
Abstract
Brain imaging techniques that use vascular signals to map changes in neuronal activity rely on the coupling between electrophysiology and hemodynamics, a phenomenon referred to as "neurovascular coupling" (NVC). It is unknown whether this relationship remains reliable under altered brain states associated with acetylcholine (ACh) levels, such as attention and arousal and in pathological conditions such as Alzheimer's disease. We therefore assessed the effects of varying ACh tone on whisker-evoked NVC responses in rat barrel cortex, measured by cerebral blood flow (CBF) and neurophysiological recordings (local field potentials, LFPs). We found that acutely enhanced ACh tone significantly potentiated whisker-evoked CBF responses through muscarinic ACh receptors and concurrently facilitated neuronal responses, as illustrated by increases in the amplitude and power in high frequencies of the evoked LFPs. However, the cellular identity of the activated neuronal network within the responsive barrel was unchanged, as characterized by c-Fos upregulation in pyramidal cells and GABA interneurons coexpressing vasoactive intestinal polypeptide. In contrast, chronic ACh deprivation hindered whisker-evoked CBF responses and the amplitude and power in most frequency bands of the evoked LFPs and reduced the rostrocaudal extent and area of the activated barrel without altering its identity. Correlations between LFP power and CBF, used to estimate NVC, were enhanced under high ACh tone and disturbed significantly by ACh depletion. We conclude that ACh is not only a facilitator but also a prerequisite for the full expression of sensory-evoked NVC responses, indicating that ACh may alter the fidelity of hemodynamic signals in assessing changes in evoked neuronal activity.SIGNIFICANCE STATEMENT Neurovascular coupling, defined as the tight relationship between activated neurons and hemodynamic responses, is a fundamental brain function that underlies hemodynamic-based functional brain imaging techniques. However, the impact of altered brain states on this relationship is largely unknown. We therefore investigated how acetylcholine (ACh), known to drive brain states of attention and arousal and to be deficient in pathologies such as Alzheimer's disease, would alter neurovascular coupling responses to sensory stimulation. Whereas acutely increased ACh enhanced neuronal responses and the resulting hemodynamic signals, chronic loss of cholinergic input resulted in dramatic impairments in both types of sensory-evoked signals. We conclude that ACh is not only a potent modulator but also a requirement for the full expression of sensory-evoked neurovascular coupling responses.
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Affiliation(s)
- Clotilde Lecrux
- Laboratory of Cerebrovascular Research and
- Laboratory of Brain Imaging Signals, Montreal Neurological Institute, McGill University, Montréal, Quebec, Canada H3A 2B4
| | | | - Sujaya Neupane
- Laboratory of Brain Imaging Signals, Montreal Neurological Institute, McGill University, Montréal, Quebec, Canada H3A 2B4
| | - Pascal Kropf
- Laboratory of Brain Imaging Signals, Montreal Neurological Institute, McGill University, Montréal, Quebec, Canada H3A 2B4
| | | | | | | | - Amir Shmuel
- Laboratory of Brain Imaging Signals, Montreal Neurological Institute, McGill University, Montréal, Quebec, Canada H3A 2B4
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Hemodynamic Changes Associated with Interictal Spikes Induced by Acute Models of Focal Epilepsy in Rats: A Simultaneous Electrocorticography and Near-Infrared Spectroscopy Study. Brain Topogr 2017; 30:390-407. [DOI: 10.1007/s10548-016-0541-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/15/2016] [Indexed: 02/07/2023]
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117
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Struys T, Govaerts K, Oosterlinck W, Casteels C, Bronckaers A, Koole M, Van Laere K, Herijgers P, Lambrichts I, Himmelreich U, Dresselaers T. In vivo evidence for long-term vascular remodeling resulting from chronic cerebral hypoperfusion in mice. J Cereb Blood Flow Metab 2017; 37:726-739. [PMID: 26994041 PMCID: PMC5381461 DOI: 10.1177/0271678x16638349] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We have characterized both acute and long-term vascular and metabolic effects of unilateral common carotid artery occlusion in mice by in vivo magnetic resonance imaging and positron emission tomography. This common carotid artery occlusion model induces chronic cerebral hypoperfusion and is therefore relevant to both preclinical stroke studies, where it serves as a control condition for a commonly used mouse model of ischemic stroke, and neurodegeneration, as chronic hypoperfusion is causative to cognitive decline. By using perfusion magnetic resonance imaging, we demonstrate that under isoflurane anesthesia, cerebral perfusion levels recover gradually over one month. This recovery is paralleled by an increase in lumen diameter and altered tortuosity of the contralateral internal carotid artery at one year post-ligation as derived from magnetic resonance angiography data. Under urethane/α-chloralose anesthesia, no acute perfusion differences are observed, but the vascular response capacity to hypercapnia is found to be compromised. These hemispheric perfusion alterations are confirmed by water [15O]-H2O positron emission tomography. Glucose metabolism ([18F]-FDG positron emission tomography) or white matter organization (diffusion-weighted magnetic resonance imaging) did not show any significant alterations. In conclusion, permanent unilateral common carotid artery occlusion results in acute and long-term vascular remodeling, which may have immediate consequences for animal models of stroke but also vascular dementia.
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Affiliation(s)
- Tom Struys
- 1 Biomedical Research Institute - Morphology Research Group, Hasselt University, Hasselt, Belgium
| | - Kristof Govaerts
- 2 Biomedical MRI Unit - MoSAIC, Department of Imaging & Pathology, KU Leuven, Leuven, Belgium
| | - Wouter Oosterlinck
- 3 Research Unit of Experimental Cardiac Surgery, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Cindy Casteels
- 4 Nuclear Medicine - MoSAIC, Department of Imaging & Pathology, KU Leuven, Leuven, Belgium
| | - Annelies Bronckaers
- 1 Biomedical Research Institute - Morphology Research Group, Hasselt University, Hasselt, Belgium
| | - Michel Koole
- 4 Nuclear Medicine - MoSAIC, Department of Imaging & Pathology, KU Leuven, Leuven, Belgium
| | - Koen Van Laere
- 4 Nuclear Medicine - MoSAIC, Department of Imaging & Pathology, KU Leuven, Leuven, Belgium
| | - Paul Herijgers
- 3 Research Unit of Experimental Cardiac Surgery, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Ivo Lambrichts
- 1 Biomedical Research Institute - Morphology Research Group, Hasselt University, Hasselt, Belgium
| | - Uwe Himmelreich
- 2 Biomedical MRI Unit - MoSAIC, Department of Imaging & Pathology, KU Leuven, Leuven, Belgium
| | - Tom Dresselaers
- 2 Biomedical MRI Unit - MoSAIC, Department of Imaging & Pathology, KU Leuven, Leuven, Belgium.,5 Radiology, University Hospitals, Leuven, Belgium
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118
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Rungta RL, Osmanski BF, Boido D, Tanter M, Charpak S. Light controls cerebral blood flow in naive animals. Nat Commun 2017; 8:14191. [PMID: 28139643 PMCID: PMC5290324 DOI: 10.1038/ncomms14191] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 12/07/2016] [Indexed: 01/05/2023] Open
Abstract
Optogenetics is increasingly used to map brain activation using techniques that rely on functional hyperaemia, such as opto-fMRI. Here we test whether light stimulation protocols similar to those commonly used in opto-fMRI or to study neurovascular coupling modulate blood flow in mice that do not express light sensitive proteins. Combining two-photon laser scanning microscopy and ultrafast functional ultrasound imaging, we report that in the naive mouse brain, light per se causes a calcium decrease in arteriolar smooth muscle cells, leading to pronounced vasodilation, without excitation of neurons and astrocytes. This photodilation is reversible, reproducible and energy-dependent, appearing at about 0.5 mJ. These results impose careful consideration on the use of photo-activation in studies involving blood flow regulation, as well as in studies requiring prolonged and repetitive stimulations to correct cellular defects in pathological models. They also suggest that light could be used to locally increase blood flow in a controlled fashion. Combination of optogenetics and BOLD fMRI is routinely used to map neuronal activity upon photostimulation. Here the authors show that light, shone at intensities used in optogenetic studies, dilates vessels and increases blood flow independently of exogenous light-sensitive proteins in the mouse brain.
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Affiliation(s)
- Ravi L Rungta
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Bruno-Félix Osmanski
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Davide Boido
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Mickael Tanter
- Institut Langevin, Espci Paris, CNRS UMR 7587, INSERM U979, PSL Research University, 17 rue Moreau, Paris 75012, France
| | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
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Cao R, Li J, Ning B, Sun N, Wang T, Zuo Z, Hu S. Functional and oxygen-metabolic photoacoustic microscopy of the awake mouse brain. Neuroimage 2017; 150:77-87. [PMID: 28111187 DOI: 10.1016/j.neuroimage.2017.01.049] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 12/10/2016] [Accepted: 01/19/2017] [Indexed: 01/22/2023] Open
Abstract
A long-standing challenge in optical neuroimaging has been the assessment of hemodynamics and oxygen metabolism in the awake rodent brain at the microscopic level. Here, we report first-of-a-kind head-restrained photoacoustic microscopy (PAM), which enables simultaneous imaging of the cerebrovascular anatomy, total concentration and oxygen saturation of hemoglobin, and blood flow in awake mice. Combining these hemodynamic measurements allows us to derive two key metabolic parameters-oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2). This enabling technology offers the first opportunity to comprehensively and quantitatively characterize the hemodynamic and oxygen-metabolic responses of the mouse brain to isoflurane, a general anesthetic widely used in preclinical research and clinical practice. Side-by-side comparison of the awake and anesthetized brains reveals that isoflurane induces diameter-dependent arterial dilation, elevated blood flow, and reduced OEF in a dose-dependent manner. As a result of the combined effects, CMRO2 is significantly reduced in the anesthetized brain under both normoxia and hypoxia, which suggests a mechanism for anesthetic neuroprotection. The head-restrained functional and metabolic PAM opens a new avenue for basic and translational research on neurovascular coupling without the strong influence of anesthesia and on the neuroprotective effects of various interventions, including but not limited to volatile anesthetics, against cerebral hypoxia and ischemia.
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Affiliation(s)
- Rui Cao
- Department of Biomedical Engineering, University of Virginia, VA 22908, USA
| | - Jun Li
- Department of Anesthesiology, University of Virginia, VA 22908, USA
| | - Bo Ning
- Department of Biomedical Engineering, University of Virginia, VA 22908, USA
| | - Naidi Sun
- Department of Biomedical Engineering, University of Virginia, VA 22908, USA
| | - Tianxiong Wang
- Department of Biomedical Engineering, University of Virginia, VA 22908, USA
| | - Zhiyi Zuo
- Department of Anesthesiology, University of Virginia, VA 22908, USA.
| | - Song Hu
- Department of Biomedical Engineering, University of Virginia, VA 22908, USA.
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120
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Wu TL, Mishra A, Wang F, Yang PF, Gore JC, Chen LM. Effects of isoflurane anesthesia on resting-state fMRI signals and functional connectivity within primary somatosensory cortex of monkeys. Brain Behav 2016; 6:e00591. [PMID: 28032008 PMCID: PMC5167001 DOI: 10.1002/brb3.591] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/15/2016] [Accepted: 09/06/2016] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Correlated low-frequency fluctuations of resting-state functional magnetic resonance imaging (rsfMRI) signals have been widely used for inferring intrinsic brain functional connectivity (FC). In animal studies, accurate estimate of anesthetic effects on rsfMRI signals is demanded for reliable interpretations of FC changes. We have previously shown that inter-regional FC can reliably delineate local millimeter-scale circuits within digit representations of primary somatosensory cortex (S1) subregions (areas 3a, 3b, and 1) in monkeys under isoflurane anesthesia. The goals of this study are to determine (1) the general effects of isoflurane on rsfMRI signals in the S1 circuit and (2) whether the effects are functional- and regional- dependent, by quantifying the relationships between isoflurane levels, power and inter-regional correlation coefficients in digit and face regions of distinct S1 subregions. METHODS Functional MRI data were collected from male adult squirrel monkeys at three different isoflurane levels (1.25%, 0.875%, and 0.5%). All scans were acquired on a 9.4T magnet with a 3-cm-diameter surface transmit-receive coil centered over the S1 cortex. Power and seed-based inter-regional functional connectivity analyses were subsequently performed. RESULTS As anesthesia level increased, we observed (1) diminishing amplitudes of signal fluctuations, (2) reduced power of fluctuations in the low-frequency band used for connectivity measurements, (3) decreased inter-voxel connectivity around seed regions, and (4) weakened inter-regional FC across all pairs of regions of interest (digit-to-digit). The low-frequency power measures derived from rsfMRI signals from control muscle regions, however, did not exhibit any isoflurane level-related changes. Within the isoflurane dosage range we tested, the inter-regional functional connectivity differences were still detectable, and the effects of isoflurane did not differ across region-of-interest (ROI) pairs. CONCLUSION Our data demonstrate that isoflurane induced similar dose-dependent suppressive effects on the power of rsfMRI signals and local fine-scale FC across functionally related but distinct S1 subregions.
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Affiliation(s)
- Tung-Lin Wu
- Vanderbilt University Institute of Imaging Science Nashville TN USA; Biomedical Engineering Vanderbilt University Nashville TN USA
| | - Arabinda Mishra
- Vanderbilt University Institute of Imaging Science Nashville TN USA; Radiology and Radiological Sciences Vanderbilt University Nashville TN USA
| | - Feng Wang
- Vanderbilt University Institute of Imaging Science Nashville TN USA; Radiology and Radiological Sciences Vanderbilt University Nashville TN USA
| | - Pai-Feng Yang
- Vanderbilt University Institute of Imaging Science Nashville TN USA; Radiology and Radiological Sciences Vanderbilt University Nashville TN USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science Nashville TN USA; Biomedical Engineering Vanderbilt University Nashville TN USA; Radiology and Radiological Sciences Vanderbilt University Nashville TN USA
| | - Li Min Chen
- Vanderbilt University Institute of Imaging Science Nashville TN USA; Radiology and Radiological Sciences Vanderbilt University Nashville TN USA
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121
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Gao YR, Ma Y, Zhang Q, Winder AT, Liang Z, Antinori L, Drew PJ, Zhang N. Time to wake up: Studying neurovascular coupling and brain-wide circuit function in the un-anesthetized animal. Neuroimage 2016; 153:382-398. [PMID: 27908788 PMCID: PMC5526447 DOI: 10.1016/j.neuroimage.2016.11.069] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 11/18/2016] [Accepted: 11/27/2016] [Indexed: 01/08/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) has allowed the noninvasive study of task-based and resting-state brain dynamics in humans by inferring neural activity from blood-oxygenation-level dependent (BOLD) signal changes. An accurate interpretation of the hemodynamic changes that underlie fMRI signals depends on the understanding of the quantitative relationship between changes in neural activity and changes in cerebral blood flow, oxygenation and volume. While there has been extensive study of neurovascular coupling in anesthetized animal models, anesthesia causes large disruptions of brain metabolism, neural responsiveness and cardiovascular function. Here, we review work showing that neurovascular coupling and brain circuit function in the awake animal are profoundly different from those in the anesthetized state. We argue that the time is right to study neurovascular coupling and brain circuit function in the awake animal to bridge the physiological mechanisms that underlie animal and human neuroimaging signals, and to interpret them in light of underlying neural mechanisms. Lastly, we discuss recent experimental innovations that have enabled the study of neurovascular coupling and brain-wide circuit function in un-anesthetized and behaving animal models.
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Affiliation(s)
- Yu-Rong Gao
- Neuroscience Graduate Program, Pennsylvania State University, University Park, PA 16802, Unidted States; Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, Unidted States
| | - Yuncong Ma
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, Unidted States
| | - Qingguang Zhang
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, Unidted States
| | - Aaron T Winder
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, Unidted States
| | - Zhifeng Liang
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, Unidted States
| | - Lilith Antinori
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, Unidted States
| | - Patrick J Drew
- Neuroscience Graduate Program, Pennsylvania State University, University Park, PA 16802, Unidted States; Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, Unidted States; Department of Neurosurgery, Pennsylvania State University, University Park, PA 16802, Unidted States; Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, Unidted States.
| | - Nanyin Zhang
- Neuroscience Graduate Program, Pennsylvania State University, University Park, PA 16802, Unidted States; Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, Unidted States.
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122
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Paasonen J, Salo RA, Huttunen JK, Gröhn O. Resting-state functional MRI as a tool for evaluating brain hemodynamic responsiveness to external stimuli in rats. Magn Reson Med 2016; 78:1136-1146. [PMID: 27774631 DOI: 10.1002/mrm.26496] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/06/2016] [Accepted: 09/14/2016] [Indexed: 11/11/2022]
Abstract
PURPOSE Anesthesia is a major confounding factor in functional MRI (fMRI) experiments attributed to its effects on brain function. Recent evidence suggests that parameters obtained with resting-state fMRI (rs-fMRI) are coupled with anesthetic depth. Therefore, we investigated whether parameters obtained with rs-fMRI, such as functional connectivity (FC), are also directly related to blood-oxygen-level-dependent (BOLD) responses. METHODS A simple rs-fMRI protocol was implemented in a pharmacological fMRI study to evaluate the coupling between hemodynamic responses and FC under five anesthetics (α-chloralose, isoflurane, medetomidine, thiobutabarbital, and urethane). Temporal change in the FC was evaluated at 1-hour interval. Supplementary forepaw stimulation experiments were also conducted. RESULTS Under thiobutabarbital anesthesia, FC was clearly coupled with nicotine-induced BOLD responses. Good correlation values were also obtained under isoflurane and medetomidine anesthesia. The observations in the thiobutabarbital group were supported by forepaw stimulation experiments. Additionally, the rs-fMRI protocol revealed significant temporal changes in the FC in the α-chloralose, thiobutabarbital, and urethane groups. CONCLUSION Our results suggest that FC can be used to estimate brain hemodynamic responsiveness to stimuli and evaluate the level and temporal changes of anesthesia. Therefore, analysis of the fMRI baseline signal may be highly valuable tool for controlling the outcome of preclinical fMRI experiments. Magn Reson Med 78:1136-1146, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jaakko Paasonen
- A.I.V. Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland
| | - Raimo A Salo
- A.I.V. Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland
| | - Joanna K Huttunen
- A.I.V. Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland
| | - Olli Gröhn
- A.I.V. Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland
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123
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Smith JB, Liang Z, Watson GDR, Alloway KD, Zhang N. Interhemispheric resting-state functional connectivity of the claustrum in the awake and anesthetized states. Brain Struct Funct 2016; 222:2041-2058. [PMID: 27714529 DOI: 10.1007/s00429-016-1323-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 09/28/2016] [Indexed: 11/30/2022]
Abstract
The claustrum is a brain region whose function remains unknown, though many investigators suggest it plays a role in conscious attention. Resting-state functional magnetic resonance imaging (RS-fMRI) has revealed how anesthesia alters many functional connections in the brain, but the functional role of the claustrum with respect to the awake versus anesthetized states remains unknown. Therefore, we employed a combination of seed-based RS-fMRI and neuroanatomical tracing to reveal how the anatomical connections of the claustrum are related to its functional connectivity during quiet wakefulness and the isoflurane-induced anesthetic state. In awake rats, RS-fMRI indicates that the claustrum has interhemispheric functional connections with the mediodorsal thalamus (MD) and medial prefrontal cortex (mPFC), as well as other known connections with cortical areas that correspond to the connections revealed by neuroanatomical tracing. During deep isoflurane anesthesia, the functional connections of the claustrum with mPFC and MD were significantly attenuated, while those with the rest of cortex were not significantly altered. These changes in claustral functional connectivity were also observed when seeds were placed in mPFC or MD during RS-fMRI comparisons of the awake and deeply anesthetized states. Collectively, these data indicate that the claustrum has functional connections with mPFC and MD-thalamus that are significantly lessened by anesthesia.
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Affiliation(s)
- Jared B Smith
- Department of Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA.,Center for Neural Engineering, Penn State University, W-316 Millennium Science Complex, University Park, PA, 16802, USA.,Department of Neural and Behavioral Sciences, Penn State University, Hershey, PA, 17033, USA.,Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Zhifeng Liang
- Center for Neural Engineering, Penn State University, W-316 Millennium Science Complex, University Park, PA, 16802, USA.,Department of Biomedical Engineering, Penn State University, W-341 Millennium Science Complex, University Park, PA, 16802, USA.,The Huck Institutes of Life Sciences, Penn State University, University Park, PA, 16802, USA.,Laboratory of Comparative Neuroimaging, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Glenn D R Watson
- Center for Neural Engineering, Penn State University, W-316 Millennium Science Complex, University Park, PA, 16802, USA.,The Huck Institutes of Life Sciences, Penn State University, University Park, PA, 16802, USA.,Department of Neural and Behavioral Sciences, Penn State University, Hershey, PA, 17033, USA
| | - Kevin D Alloway
- Center for Neural Engineering, Penn State University, W-316 Millennium Science Complex, University Park, PA, 16802, USA. .,The Huck Institutes of Life Sciences, Penn State University, University Park, PA, 16802, USA. .,Department of Neural and Behavioral Sciences, Penn State University, Hershey, PA, 17033, USA.
| | - Nanyin Zhang
- Center for Neural Engineering, Penn State University, W-316 Millennium Science Complex, University Park, PA, 16802, USA. .,Department of Biomedical Engineering, Penn State University, W-341 Millennium Science Complex, University Park, PA, 16802, USA. .,The Huck Institutes of Life Sciences, Penn State University, University Park, PA, 16802, USA.
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Noninvasive Measurement of Cerebral Blood Flow Under Anesthesia Using Arterial Spin Labeling MRI: A Pilot Study. J Neurosurg Anesthesiol 2016; 28:331-6. [DOI: 10.1097/ana.0000000000000231] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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125
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Yoshida K, Mimura Y, Ishihara R, Nishida H, Komaki Y, Minakuchi T, Tsurugizawa T, Mimura M, Okano H, Tanaka KF, Takata N. Physiological effects of a habituation procedure for functional MRI in awake mice using a cryogenic radiofrequency probe. J Neurosci Methods 2016; 274:38-48. [PMID: 27702586 DOI: 10.1016/j.jneumeth.2016.09.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 09/26/2016] [Accepted: 09/30/2016] [Indexed: 01/02/2023]
Abstract
BACKGROUND Functional magnetic resonance imaging (fMRI) in mice is typically performed under anesthesia due to difficulties in holding the head of awake mice stably with a conventional three-point fixation method that uses a tooth-bar and earplugs. Although some studies have succeeded in fMRI in awake mice by attaching a head-post on the skull, this cannot be applied to fMRI using a high signal-to-noise ratio (SNR) cryogenic MRI-detector, CryoProbe, because it covers the head of a mouse closely. NEW METHOD We developed head-fixation implements for awake mice that are applicable to fMRI using CryoProbe. RESULTS A head-bar was surgically attached to the skull of a mouse that was then habituated to a mock fMRI-environment, two hours/day for eight days with physiological examinations of body-weight, fecal weight, electromyogram (EMG), and electrocardiogram. EMG power decreased with just one day of habituation, whereas heart rate decreased after at least seven days of habituation. Estimated head motions of awake mice during fMRI were significantly smaller than a voxel size. Unexpectedly, temporal SNR of fMRI signals for awake mice was higher than that for anesthetized mice held by a conventional method. Functional connectivity in the brain of both anesthetized and awake mice showed bilateral and unilateral networks. COMPARISON WITH EXISTING METHOD(S): fMRI using CryoProbe had been performed on anesthetized mice previously. Our method does not use anesthetics during habituation or fMRI. CONCLUSION Our method would be beneficial for translational research using fMRI in mice and humans because human fMRI is typically performed without anesthetics.
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Affiliation(s)
- Keitaro Yoshida
- Department of Neuropsychiatry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Yu Mimura
- Department of Neuropsychiatry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Ryosuke Ishihara
- Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Hiroshi Nishida
- Department of Neuropsychiatry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Yuji Komaki
- Central Institute for Experimental Animals (CIEA), 3-25-12 Tonomachi, Kawasaki, Kanagawa 210-0821, Japan
| | - Tomohito Minakuchi
- Department of Neuropsychiatry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Tomokazu Tsurugizawa
- NeuroSpin, Commissariat à l'Energie Atomique et aux Energies Alternatives, 91191 Gif-sur-Yvette, France
| | - Masaru Mimura
- Department of Neuropsychiatry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Hideyuki Okano
- Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Kenji F Tanaka
- Department of Neuropsychiatry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Norio Takata
- Department of Neuropsychiatry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan; Central Institute for Experimental Animals (CIEA), 3-25-12 Tonomachi, Kawasaki, Kanagawa 210-0821, Japan.
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Sigal I, Koletar MM, Ringuette D, Gad R, Jeffrey M, Carlen PL, Stefanovic B, Levi O. Imaging brain activity during seizures in freely behaving rats using a miniature multi-modal imaging system. BIOMEDICAL OPTICS EXPRESS 2016; 7:3596-3609. [PMID: 27699123 PMCID: PMC5030035 DOI: 10.1364/boe.7.003596] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 08/11/2016] [Accepted: 08/11/2016] [Indexed: 05/20/2023]
Abstract
We report on a miniature label-free imaging system for monitoring brain blood flow and blood oxygenation changes in awake, freely behaving rats. The device, weighing 15 grams, enables imaging in a ∼ 2 × 2 mm field of view with 4.4 μm lateral resolution and 1 - 8 Hz temporal sampling rate. The imaging is performed through a chronically-implanted cranial window that remains optically clear between 2 to > 6 weeks after the craniotomy. This imaging method is well suited for longitudinal studies of chronic models of brain diseases and disorders. In this work, it is applied to monitoring neurovascular coupling during drug-induced absence-like seizures 6 weeks following the craniotomy.
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Affiliation(s)
- Iliya Sigal
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9,
Canada
- The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, 10 King’s College Road, Toronto, ON M5S 3G4,
Canada
| | - Margaret M. Koletar
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5,
Canada
| | - Dene Ringuette
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9,
Canada
| | - Raanan Gad
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9,
Canada
- The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, 10 King’s College Road, Toronto, ON M5S 3G4,
Canada
| | - Melanie Jeffrey
- Krembil Research Institute, 60 Leonard Avenue, Toronto, ON M5T 2S1,
Canada
| | - Peter L. Carlen
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9,
Canada
- Krembil Research Institute, 60 Leonard Avenue, Toronto, ON M5T 2S1,
Canada
| | - Bojana Stefanovic
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5,
Canada
- Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5,
Canada
| | - Ofer Levi
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9,
Canada
- The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, 10 King’s College Road, Toronto, ON M5S 3G4,
Canada
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127
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Ketamine-dependent neuronal activation in healthy volunteers. Brain Struct Funct 2016; 222:1533-1542. [PMID: 27578365 DOI: 10.1007/s00429-016-1291-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 08/12/2016] [Indexed: 01/03/2023]
Abstract
Over the last years, a number of studies have been conducted to clarify the neurobiological correlates of ketamine application. However, comprehensive information regarding the influence of ketamine on cortical activity is still lacking. Using resting-state functional MRI and integrating pharmacokinetic information, a double-blind, randomized, placebo-controlled, crossover study was performed to determine the effects of ketamine on neuronal activation. During a 55 min resting-state fMRI scan, esketamine (Ketanest S®) was administered intravenously to 35 healthy volunteers. Neural activation as indicated by the BOLD signal using the pharmacokinetic curve of ketamine plasma levels as a regressor was computed. Compared with placebo, ketamine-dependent increases of neural activation were observed in the midcingulate cortex, the dorsal part of the anterior cingulate cortex, the insula bilaterally, and the thalamus (t values ranging between 5.95-9.78, p < 0.05; FWE-corrected). A significant decrease of neural activation in the ketamine condition compared to placebo was found in a cluster within the subgenual/subcallosal part of the anterior cingulate cortex, the orbitofrontal cortex and the gyrus rectus (t = 7.81, p < 0.05, FWE-corrected). Using an approach combining pharmacological and fMRI data, important information about the neurobiological correlates of the clinical antidepressant effects of ketamine could be revealed.
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128
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Takuwa H, Ikoma Y, Yoshida E, Tashima H, Wakizaka H, Shinaji T, Yamaya T. Development of a simultaneous optical/PET imaging system for awake mice. Phys Med Biol 2016; 61:6430-40. [PMID: 27514436 DOI: 10.1088/0031-9155/61/17/6430] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Simultaneous measurements of multiple physiological parameters are essential for the study of brain disease mechanisms and the development of suitable therapies to treat them. In this study, we developed a measurement system for simultaneous optical imaging and PET for awake mice. The key elements of this system are the OpenPET, optical imaging and fixation apparatus for an awake mouse. The OpenPET is our original open-type PET geometry, which can be used in combination with another device because of the easily accessible open space of the former. A small prototype of the axial shift single-ring OpenPET was used. The objective lens for optical imaging with a mounted charge-coupled device camera was placed inside the open space of the AS-SROP. Our original fixation apparatus to hold an awake mouse was also applied. As a first application of this system, simultaneous measurements of cerebral blood flow (CBF) by laser speckle imaging (LSI) and [(11)C]raclopride-PET were performed under control and 5% CO2 inhalation (hypercapnia) conditions. Our system successfully obtained the CBF and [(11)C]raclopride radioactivity concentration simultaneously. Accumulation of [(11)C]raclopride was observed in the striatum where the density of dopamine D2 receptors is high. LSI measurements could be stably performed for more than 60 minutes. Increased CBF induced by hypercapnia was observed while CBF under the control condition was stable. We concluded that our imaging system should be useful for investigating the mechanisms of brain diseases in awake animal models.
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Affiliation(s)
- Hiroyuki Takuwa
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
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129
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Effects of Voluntary Locomotion and Calcitonin Gene-Related Peptide on the Dynamics of Single Dural Vessels in Awake Mice. J Neurosci 2016; 36:2503-16. [PMID: 26911696 DOI: 10.1523/jneurosci.3665-15.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The dura mater is a vascularized membrane surrounding the brain and is heavily innervated by sensory nerves. Our knowledge of the dural vasculature has been limited to pathological conditions, such as headaches, but little is known about the dural blood flow regulation during behavior. To better understand the dynamics of dural vessels during behavior, we used two-photon laser scanning microscopy (2PLSM) to measure the diameter changes of single dural and pial vessels in the awake mouse during voluntary locomotion. Surprisingly, we found that voluntary locomotion drove the constriction of dural vessels, and the dynamics of these constrictions could be captured with a linear convolution model. Dural vessel constrictions did not mirror the large increases in intracranial pressure (ICP) during locomotion, indicating that dural vessel constriction was not caused passively by compression. To study how behaviorally driven dynamics of dural vessels might be altered in pathological states, we injected the vasodilator calcitonin gene-related peptide (CGRP), which induces headache in humans. CGRP dilated dural, but not pial, vessels and significantly reduced spontaneous locomotion but did not block locomotion-induced constrictions in dural vessels. Sumatriptan, a drug commonly used to treat headaches, blocked the vascular and behavioral the effects of CGRP. These findings suggest that, in the awake animal, the diameters of dural vessels are regulated dynamically during behavior and during drug-induced pathological states.
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130
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Dienel GA, Cruz NF. Aerobic glycolysis during brain activation: adrenergic regulation and influence of norepinephrine on astrocytic metabolism. J Neurochem 2016; 138:14-52. [DOI: 10.1111/jnc.13630] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/24/2016] [Accepted: 03/31/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Gerald A. Dienel
- Department of Cell Biology and Physiology; University of New Mexico; Albuquerque; New Mexico USA
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
| | - Nancy F. Cruz
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
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131
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Wearable 3-D Photoacoustic Tomography for Functional Brain Imaging in Behaving Rats. Sci Rep 2016; 6:25470. [PMID: 27146026 PMCID: PMC4857106 DOI: 10.1038/srep25470] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/18/2016] [Indexed: 01/11/2023] Open
Abstract
Understanding the relationship between brain function and behavior remains a major challenge in neuroscience. Photoacoustic tomography (PAT) is an emerging technique that allows for noninvasive in vivo brain imaging at micrometer-millisecond spatiotemporal resolution. In this article, a novel, miniaturized 3D wearable PAT (3D-wPAT) technique is described for brain imaging in behaving rats. 3D-wPAT has three layers of fully functional acoustic transducer arrays. Phantom imaging experiments revealed that the in-plane X-Y spatial resolutions were ~200 μm for each acoustic detection layer. The functional imaging capacity of 3D-wPAT was demonstrated by mapping the cerebral oxygen saturation via multi-wavelength irradiation in behaving hyperoxic rats. In addition, we demonstrated that 3D-wPAT could be used for monitoring sensory stimulus-evoked responses in behaving rats by measuring hemodynamic responses in the primary visual cortex during visual stimulation. Together, these results show the potential of 3D-wPAT for brain study in behaving rodents.
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132
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Slack R, Boorman L, Patel P, Harris S, Bruyns-Haylett M, Kennerley A, Jones M, Berwick J. A novel method for classifying cortical state to identify the accompanying changes in cerebral hemodynamics. J Neurosci Methods 2016; 267:21-34. [PMID: 27063501 PMCID: PMC4896992 DOI: 10.1016/j.jneumeth.2016.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 03/29/2016] [Accepted: 04/06/2016] [Indexed: 11/27/2022]
Abstract
We classified brain state using a vector-based categorisation of neural frequencies. Changes in cerebral blood volume (CBV) were observed when brain state altered. During these state alterations, changes in blood oxygenation were also found. State dependent haemodynamic changes could affect blood based brain imaging.
Background Many brain imaging techniques interpret the haemodynamic response as an indirect indicator of underlying neural activity. However, a challenge when interpreting this blood based signal is how changes in brain state may affect both baseline and stimulus evoked haemodynamics. New method We developed an Automatic Brain State Classifier (ABSC), validated on data from anaesthetised rodents. It uses vectorised information obtained from the windowed spectral frequency power of the Local Field Potential. Current state is then classified by comparing this vectorised information against that calculated from state specific training datasets. Results The ABSC identified two user defined brain states (synchronised and desynchronised), with high accuracy (∼90%). Baseline haemodynamics were found to be significantly different in the two identified states. During state defined periods of elevated baseline haemodynamics we found significant decreases in evoked haemodynamic responses to somatosensory stimuli. Comparison to existing methods State classification – The ABSC (∼90%) demonstrated greater accuracy than clustering (∼66%) or ‘power threshold’ (∼64%) methods of comparison. Haemodynamic averaging – Our novel approach of selectively averaging stimulus evoked haemodynamic trials by brain state yields higher quality data than creating a single average from all trials. Conclusions The ABSC can account for some of the commonly observed trial-to-trial variability in haemodynamic responses which arises from changes in cortical state. This variability might otherwise be incorrectly attributed to alternative interpretations. A greater understanding of the effects of cortical state on haemodynamic changes could be used to inform techniques such as general linear modelling (GLM), commonly used in fMRI.
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Affiliation(s)
- R Slack
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - L Boorman
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - P Patel
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - S Harris
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - M Bruyns-Haylett
- Department of Systems Engineering, University of Reading, Whiteknights, Reading RG6 6AY, United Kingdom.
| | - A Kennerley
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - M Jones
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - J Berwick
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
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133
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Murugan M, Santhakumar V, Kannurpatti SS. Facilitating Mitochondrial Calcium Uptake Improves Activation-Induced Cerebral Blood Flow and Behavior after mTBI. Front Syst Neurosci 2016; 10:19. [PMID: 27013987 PMCID: PMC4782040 DOI: 10.3389/fnsys.2016.00019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 02/19/2016] [Indexed: 11/13/2022] Open
Abstract
Mild to moderate traumatic brain injury (mTBI) leads to secondary neuronal loss via excitotoxic mechanisms, including mitochondrial Ca(2+) overload. However, in the surviving cellular population, mitochondrial Ca(2+) influx, and oxidative metabolism are diminished leading to suboptimal neuronal circuit activity and poor prognosis. Hence we tested the impact of boosting neuronal electrical activity and oxidative metabolism by facilitating mitochondrial Ca(2+) uptake in a rat model of mTBI. In developing rats (P25-P26) sustaining an mTBI, we demonstrate post-traumatic changes in cerebral blood flow (CBF) in the sensorimotor cortex in response to whisker stimulation compared to sham using functional Laser Doppler Imaging (fLDI) at adulthood (P67-P73). Compared to sham, whisker stimulation-evoked positive CBF responses decreased while negative CBF responses increased in the mTBI animals. The spatiotemporal CBF changes representing underlying neuronal activity suggested profound changes to neurovascular activity after mTBI. Behavioral assessment of the same cohort of animals prior to fLDI showed that mTBI resulted in persistent contralateral sensorimotor behavioral deficit along with ipsilateral neuronal loss compared to sham. Treating mTBI rats with Kaempferol, a dietary flavonol compound that enhanced mitochondrial Ca(2+) uptake, eliminated the inter-hemispheric asymmetry in the whisker stimulation-induced positive CBF responses and the ipsilateral negative CBF responses otherwise observed in the untreated and vehicle-treated mTBI animals in adulthood. Kaempferol also improved somatosensory behavioral measures compared to untreated and vehicle treated mTBI animals without augmenting post-injury neuronal loss. The results indicate that reduced mitochondrial Ca(2+) uptake in the surviving populations affect post-traumatic neural activation leading to persistent behavioral deficits. Improvement in sensorimotor behavior and spatiotemporal neurovascular activity following kaempferol treatment suggests that facilitation of mitochondrial Ca(2+) uptake in the early window after injury may sustain optimal neural activity and metabolism and contribute to improved function of the surviving cellular populations after mTBI.
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Affiliation(s)
- Madhuvika Murugan
- Department of Radiology, Rutgers New Jersey Medical School Newark, NJ, USA
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School Newark, NJ, USA
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134
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Bailey J, Taylor K. Non-human Primates in Neuroscience Research: The Case against its Scientific Necessity. Altern Lab Anim 2016; 44:43-69. [DOI: 10.1177/026119291604400101] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Public opposition to non-human primate (NHP) experiments is significant, yet those who defend them cite minimal harm to NHPs and substantial human benefit. Here we review these claims of benefit, specifically in neuroscience, and show that: a) there is a default assumption of their human relevance and benefit, rather than robust evidence; b) their human relevance and essential contribution and necessity are wholly overstated; c) the contribution and capacity of non-animal investigative methods are greatly understated; and d) confounding issues, such as species differences and the effects of stress and anaesthesia, are usually overlooked. This is the case in NHP research generally, but here we specifically focus on the development and interpretation of functional magnetic resonance imaging (fMRI), deep brain stimulation (DBS), the understanding of neural oscillations and memory, and investigation of the neural control of movement and of vision/binocular rivalry. The increasing power of human-specific methods, including advances in fMRI and invasive techniques such as electrocorticography and single-unit recordings, is discussed. These methods serve to render NHP approaches redundant. We conclude that the defence of NHP use is groundless, and that neuroscience would be more relevant and successful for humans, if it were conducted with a direct human focus. We have confidence in opposing NHP neuroscience, both on scientific as well as on ethical grounds.
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135
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Comparison of seven different anesthesia protocols for nicotine pharmacologic magnetic resonance imaging in rat. Eur Neuropsychopharmacol 2016; 26:518-31. [PMID: 26796682 DOI: 10.1016/j.euroneuro.2015.12.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 10/19/2015] [Accepted: 12/20/2015] [Indexed: 11/21/2022]
Abstract
Pharmacologic MRI (phMRI) is a non-invasive in vivo imaging method, which can evaluate the drug effects on the brain and provide complementary information to ex vivo techniques. The preclinical phMRI studies usually require anesthesia to reduce the motion and stress of the animals. The anesthesia, however, is a crucial part of the experimental design, as it may modulate the neural drug-induced (de)activation and hemodynamic coupling. Therefore, the aim of the present study was to address this methodologic question by performing phMRI experiments with five anesthetics (α-chloralose, isoflurane, medetomidine, thiobutabarbital, and urethane) and seven anesthesia protocols. Nicotine, a widely studied psychostimulant, was administered to rats while measuring blood oxygenation level-dependent (BOLD) signals. Notably different responses were observed depending on the anesthetic used. The highest responses were measured in urethane-anesthetized rats whereas the responses were hardly noticeable in α-chloralose group. As urethane is not commonly used in phMRI, hemodynamic coupling under urethane anesthesia was investigated with functional cerebral blood flow (CBF) and volume-weighted (CBVw) imaging, and simultaneous electrophysiologic and BOLD measurements. The BOLD, CBF, and CBVw measurements in response to nicotine were highly correlated (R(2) ≥ 0.70, p<0.001). BOLD values correlated well (R(2)=0.43, p<10(-6)) with local field potential (LFP) spectral power (13-70Hz) during pharmacologic stimulation. These findings indicate that urethane anesthesia combined with BOLD contrast provides a robust protocol for nicotine phMRI studies. As urethane has mild effects to individual receptor systems, and coupling between electrophysiologic activity and hemodynamic response is maintained, this anesthetic may also be suitable for other phMRI studies.
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136
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Lee W, Lee SD, Park MY, Foley L, Purcell-Estabrook E, Kim H, Fischer K, Maeng LS, Yoo SS. Image-Guided Focused Ultrasound-Mediated Regional Brain Stimulation in Sheep. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:459-470. [PMID: 26525652 DOI: 10.1016/j.ultrasmedbio.2015.10.001] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 09/17/2015] [Accepted: 10/01/2015] [Indexed: 06/05/2023]
Abstract
Non-invasive brain stimulation using focused ultrasound has largely been carried out in small animals. In the present study, we applied stimulatory focused ultrasound transcranially to the primary sensorimotor (SM1) and visual (V1) brain areas in sheep (Dorset, all female, n = 8), under the guidance of magnetic resonance imaging, and examined the electrophysiologic responses. By use of a 250-kHz focused ultrasound transducer, the area was sonicated in pulsed mode (tone-burst duration of 1 ms, duty cycle of 50%) for 300 ms. The acoustic intensity at the focal target was varied up to a spatial peak pulse-average intensity (Isppa) of 14.3 W/cm(2). Sonication of SM1 elicited electromyographic responses from the contralateral hind leg, whereas stimulation of V1 generated electroencephalographic potentials. These responses were detected only above a certain acoustic intensity, and the threshold intensity, as well as the degree of responses, varied among sheep. Post-sonication animal behavior was normal, but minor microhemorrhages were observed from the V1 areas exposed to highly repetitive sonication (every second for ≥500 times for electroencephalographic measurements, Isppa = 6.6-10.5 W/cm(2), mechanical index = 0.9-1.2). Our results suggest the potential translational utility of focused ultrasound as a new brain stimulation modality, yet also call for caution in the use of an excessive number of sonications.
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Affiliation(s)
- Wonhye Lee
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Stephanie D Lee
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael Y Park
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Lori Foley
- Invasive Cardiovascular Experimental Laboratory, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Erin Purcell-Estabrook
- Invasive Cardiovascular Experimental Laboratory, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Hyungmin Kim
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Center for Bionics, Korea Institute of Science and Technology, Seoul, Korea
| | - Krisztina Fischer
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Lee-So Maeng
- Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Seung-Schik Yoo
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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137
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Hotta H. Neurogenic control of parenchymal arterioles in the cerebral cortex. PROGRESS IN BRAIN RESEARCH 2016; 225:3-39. [DOI: 10.1016/bs.pbr.2016.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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138
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Gozzi A, Schwarz AJ. Large-scale functional connectivity networks in the rodent brain. Neuroimage 2015; 127:496-509. [PMID: 26706448 DOI: 10.1016/j.neuroimage.2015.12.017] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 12/04/2015] [Accepted: 12/11/2015] [Indexed: 02/08/2023] Open
Abstract
Resting-state functional Magnetic Resonance Imaging (rsfMRI) of the human brain has revealed multiple large-scale neural networks within a hierarchical and complex structure of coordinated functional activity. These distributed neuroanatomical systems provide a sensitive window on brain function and its disruption in a variety of neuropathological conditions. The study of macroscale intrinsic connectivity networks in preclinical species, where genetic and environmental conditions can be controlled and manipulated with high specificity, offers the opportunity to elucidate the biological determinants of these alterations. While rsfMRI methods are now widely used in human connectivity research, these approaches have only relatively recently been back-translated into laboratory animals. Here we review recent progress in the study of functional connectivity in rodent species, emphasising the ability of this approach to resolve large-scale brain networks that recapitulate neuroanatomical features of known functional systems in the human brain. These include, but are not limited to, a distributed set of regions identified in rats and mice that may represent a putative evolutionary precursor of the human default mode network (DMN). The impact and control of potential experimental and methodological confounds are also critically discussed. Finally, we highlight the enormous potential and some initial application of connectivity mapping in transgenic models as a tool to investigate the neuropathological underpinnings of the large-scale connectional alterations associated with human neuropsychiatric and neurological conditions. We conclude by discussing the translational potential of these methods in basic and applied neuroscience.
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Affiliation(s)
- Alessandro Gozzi
- Istituto Italiano di Tecnologia, Center for Neuroscience and Cognitive Systems at UniTn, Rovereto, Italy.
| | - Adam J Schwarz
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA; Department of Radiology and Imaging Sciences, Indiana University, Indianapolis, IN 46202, USA
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139
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Lv P, Xiao Y, Liu B, Wang Y, Zhang X, Sun H, Li F, Yao L, Zhang W, Liu L, Gao X, Wu M, Tang Y, Chen Q, Gong Q, Lui S. Dose-dependent effects of isoflurane on regional activity and neural network function: A resting-state fMRI study of 14 rhesus monkeys: An observational study. Neurosci Lett 2015; 611:116-22. [PMID: 26633103 DOI: 10.1016/j.neulet.2015.11.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 11/02/2015] [Accepted: 11/23/2015] [Indexed: 02/05/2023]
Abstract
The dose-dependent effect of isoflurane on cerebral regional activity and functional connectivity (FC) in 14 rhesus monkeys was investigated using resting-state functional MRI. Amplitude of low-frequency fluctuations (ALFF) decreased in the cerebellum, visual cortex, and cortico-subcortical network when the isoflurane dose changed from 1.0 to 1.3 MAC. ALFF decreased in the arousal system, cerebellum, sensory, visual areas, cortico-subcortical network and default mode network and increased in the bilateral dorsal prefrontal cortices, frontal eye fields and motor-related areas from 1.0 to 1.6 MAC. FC of the default mode network, frontal-parietal, cortico-subcortical, motor, sensory, auditory and visual areas was reduced when isoflurane increased from 1.0 to 1.3 MAC. FC decreased in more widespread areas, especially in regions of cortico-subcortical networks and limbic systems, when isoflurane further increased from 1.0 to 1.6 MAC. Both dose-dependent decreased and increased ALFF were separately observed, while FC deteriorated as the anesthesia deepened. These results suggest that changes continue to occur past the loss of consciousness, and the dose-dependent effects of isoflurane are different with regard to regional function and neural network integration.
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Affiliation(s)
- Peilin Lv
- Department of Anesthesiology, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Yuan Xiao
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Bin Liu
- Department of Anesthesiology, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China.
| | - Yuqing Wang
- Department of Radiology, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Xiang Zhang
- Department of Anesthesiology, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Huaiqiang Sun
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Fei Li
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Li Yao
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Wenjing Zhang
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Lu Liu
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Xin Gao
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Min Wu
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Yingying Tang
- Department of Neurology, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Qin Chen
- Department of Neurology, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Qiyong Gong
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China
| | - Su Lui
- Huaxi MR Research Center (HMRRC), Department of Radiology, The Center for Medical Imaging, West China Hospital of Sichuan University, #37 Guo Xue Xiang, Chengdu, Sichuan, China; Department of Radiology, The Second Affiliated Hospital & Yuying Children's Hospital of Wenzhou Medical University, #109 Xueyuan Western Road, Wenzhou, Zhejiang, China.
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140
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Havlicek M, Roebroeck A, Friston K, Gardumi A, Ivanov D, Uludag K. Physiologically informed dynamic causal modeling of fMRI data. Neuroimage 2015; 122:355-72. [DOI: 10.1016/j.neuroimage.2015.07.078] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 12/15/2022] Open
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141
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Effects of anesthesia on BOLD signal and neuronal activity in the somatosensory cortex. J Cereb Blood Flow Metab 2015; 35:1819-26. [PMID: 26104288 PMCID: PMC4635237 DOI: 10.1038/jcbfm.2015.130] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 03/30/2015] [Accepted: 05/14/2015] [Indexed: 12/13/2022]
Abstract
Most functional magnetic resonance imaging (fMRI) animal studies rely on anesthesia, which can induce a variety of drug-dependent physiological changes, including depression of neuronal activity and cerebral metabolism as well as direct effects on the vasculature. The goal of this study was to characterize the effects of anesthesia on the BOLD signal and neuronal activity. Simultaneous fMRI and electrophysiology were used to measure changes in single units (SU), multi-unit activity (MUA), local field potentials (LFP), and the blood oxygenation level-dependent (BOLD) response in the somatosensory cortex during whisker stimulation of rabbits before, during and after anesthesia with fentanyl or isoflurane. Our results indicate that anesthesia modulates the BOLD signal as well as both baseline and stimulus-evoked neuronal activity, and, most significantly, that the relationship between the BOLD and electrophysiological signals depends on the type of anesthetic. Specifically, the behavior of LFP observed under isoflurane did not parallel the behavior of BOLD, SU, or MUA. These findings suggest that the relationship between these signals may not be straightforward. BOLD may scale more closely with the best measure of the excitatory subcomponents of the underlying neuronal activity, which may vary according to experimental conditions that alter the excitatory/inhibitory balance in the cortex.
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142
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Merkle CW, Srinivasan VJ. Laminar microvascular transit time distribution in the mouse somatosensory cortex revealed by Dynamic Contrast Optical Coherence Tomography. Neuroimage 2015; 125:350-362. [PMID: 26477654 DOI: 10.1016/j.neuroimage.2015.10.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 09/15/2015] [Accepted: 10/07/2015] [Indexed: 11/15/2022] Open
Abstract
The transit time distribution of blood through the cerebral microvasculature both constrains oxygen delivery and governs the kinetics of neuroimaging signals such as blood-oxygen-level-dependent functional Magnetic Resonance Imaging (BOLD fMRI). However, in spite of its importance, capillary transit time distribution has been challenging to quantify comprehensively and efficiently at the microscopic level. Here, we introduce a method, called Dynamic Contrast Optical Coherence Tomography (DyC-OCT), based on dynamic cross-sectional OCT imaging of an intravascular tracer as it passes through the field-of-view. Quantitative transit time metrics are derived from temporal analysis of the dynamic scattering signal, closely related to tracer concentration. Since DyC-OCT does not require calibration of the optical focus, quantitative accuracy is achieved even deep in highly scattering brain tissue where the focal spot degrades. After direct validation of DyC-OCT against dilution curves measured using a fluorescent plasma label in surface pial vessels, we used DyC-OCT to investigate the transit time distribution in microvasculature across the entire depth of the mouse somatosensory cortex. Laminar trends were identified, with earlier transit times and less heterogeneity in the middle cortical layers. The early transit times in the middle cortical layers may explain, at least in part, the early BOLD fMRI onset times observed in these layers. The layer-dependencies in heterogeneity may help explain how a single vascular supply manages to deliver oxygen to individual cortical layers with diverse metabolic needs.
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Affiliation(s)
- Conrad W Merkle
- Department of Biomedical Engineering, University of California at Davis 451 E. Health Sciences Dr. GBSF 2303 Davis CA 95616, USA
| | - Vivek J Srinivasan
- Department of Biomedical Engineering, University of California at Davis 451 E. Health Sciences Dr. GBSF 2303 Davis CA 95616, USA.
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143
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He JW, Liu H, Peng YB. The Scalp Confounds Near-Infrared Signal from Rat Brain Following Innocuous and Noxious Stimulation. Brain Sci 2015; 5:387-99. [PMID: 26426058 PMCID: PMC4701019 DOI: 10.3390/brainsci5040387] [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: 07/12/2015] [Revised: 09/02/2015] [Accepted: 09/11/2015] [Indexed: 11/16/2022] Open
Abstract
Functional near-infrared imaging (fNIRI) is a non-invasive, low-cost and highly portable technique for assessing brain activity and functions. Both clinical and experimental evidence suggest that fNIRI is able to assess brain activity at associated regions during pain processing, indicating a strong possibility of using fNIRI-derived brain activity pattern as a biomarker for pain. However, it remains unclear how, especially in small animals, the scalp influences fNIRI signal in pain processing. Previously, we have shown that the use of a multi-channel system improves the spatial resolution of fNIRI in rats (without the scalp) during pain processing. Our current work is to investigate a scalp effect by comparing with new data from rats with the scalp during innocuous or noxious stimulation (n = 6). Results showed remarkable stimulus-dependent differences between the no-scalp and intact-scalp groups. In conclusion, the scalp confounded the fNIRI signal in pain processing likely via an autonomic mechanism; the scalp effect should be a critical factor in image reconstruction and data interpretation.
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Affiliation(s)
- Ji-Wei He
- Departments of Psychology, University of Texas at Arlington, Arlington, TX 76019, USA.
- Department of Neurological Surgery, University of California San Francisco, 1700 Owens Street, San Francisco, CA 94158, USA.
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76019, USA.
| | - Yuan Bo Peng
- Departments of Psychology, University of Texas at Arlington, Arlington, TX 76019, USA.
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144
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He JW, Liu H, Peng YB. Hemodynamic and Light-Scattering Changes of Rat Spinal Cord and Primary Somatosensory Cortex in Response to Innocuous and Noxious Stimuli. Brain Sci 2015; 5:400-18. [PMID: 26426059 PMCID: PMC4701020 DOI: 10.3390/brainsci5040400] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/20/2015] [Accepted: 09/24/2015] [Indexed: 12/28/2022] Open
Abstract
Neuroimaging technologies with an exceptional spatial resolution and noninvasiveness have become a powerful tool for assessing neural activity in both animals and humans. However, the effectiveness of neuroimaging for pain remains unclear partly because the neurovascular coupling during pain processing is not completely characterized. Our current work aims to unravel patterns of neurovascular parameters in pain processing. A novel fiber-optic method was used to acquire absolute values of regional oxy- (HbO) and deoxy-hemoglobin concentrations, oxygen saturation rates (SO₂), and the light-scattering coefficients from the spinal cord and primary somatosensory cortex (SI) in 10 rats. Brief mechanical and electrical stimuli (ranging from innocuous to noxious intensities) as well as a long-lasting noxious stimulus (formalin injection) were applied to the hindlimb under pentobarbital anesthesia. Interhemispheric comparisons in the spinal cord and SI were used to confirm functional activation during sensory processing. We found that all neurovascular parameters showed stimulation-induced changes; however, patterns of changes varied with regions and stimuli. Particularly, transient increases in HbO and SO₂ were more reliably attributed to brief stimuli, whereas a sustained decrease in SO₂ was more reliably attributed to formalin. Only the ipsilateral SI showed delayed responses to brief stimuli. In conclusion, innocuous and noxious stimuli induced significant neurovascular responses at critical centers (e.g., the spinal cord and SI) along the somatosensory pathway; however, there was no single response pattern (as measured by amplitude, duration, lateralization, decrease or increase) that was able to consistently differentiate noxious stimuli. Our results strongly suggested that the neurovascular response patterns differ between brief and long-lasting noxious stimuli, and can also differ between the spinal cord and SI. Therefore, a use of multiple-parameter strategy tailored by stimulus modality (brief or long-lasting) as well as region-dependent characteristics may be more effective in detecting pain using neuroimaging technologies.
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Affiliation(s)
- Ji-Wei He
- Departments of Psychology, University of Texas at Arlington, Arlington, TX 76019, USA.
- Department of Neurological Surgery, University of California San Francisco, 1700 Owens Street, San Francisco, CA 94158, USA.
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76019, USA.
| | - Yuan Bo Peng
- Departments of Psychology, University of Texas at Arlington, Arlington, TX 76019, USA.
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145
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Errico C, Osmanski BF, Pezet S, Couture O, Lenkei Z, Tanter M. Transcranial functional ultrasound imaging of the brain using microbubble-enhanced ultrasensitive Doppler. Neuroimage 2015; 124:752-761. [PMID: 26416649 PMCID: PMC4686564 DOI: 10.1016/j.neuroimage.2015.09.037] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 08/13/2015] [Accepted: 09/14/2015] [Indexed: 11/15/2022] Open
Abstract
Functional ultrasound (fUS) is a novel neuroimaging technique, based on high-sensitivity ultrafast Doppler imaging of cerebral blood volume, capable of measuring brain activation and connectivity in rodents with high spatiotemporal resolution (100 μm, 1 ms). However, the skull attenuates acoustic waves, so fUS in rats currently requires craniotomy or a thinned-skull window. Here we propose a non-invasive approach by enhancing the fUS signal with a contrast agent, inert gas microbubbles. Plane-wave illumination of the brain at high frame rate (500 Hz compounded sequence with three tilted plane waves, PRF = 1500Hz with a 128 element 15 MHz linear transducer), yields highly-resolved neurovascular maps. We compared fUS imaging performance through the intact skull bone (transcranial fUS) versus a thinned-skull window in the same animal. First, we show that the vascular network of the adult rat brain can be imaged transcranially only after a bolus intravenous injection of microbubbles, which leads to a 9 dB gain in the contrast-to-tissue ratio. Next, we demonstrate that functional increase in the blood volume of the primary sensory cortex after targeted electrical-evoked stimulations of the sciatic nerve is observable transcranially in presence of contrast agents, with high reproducibility (Pearson's coefficient ρ = 0.7 ± 0.1, p = 0.85). Our work demonstrates that the combination of ultrafast Doppler imaging and injection of contrast agent allows non-invasive functional brain imaging through the intact skull bone in rats. These results should ease non-invasive longitudinal studies in rodents and open a promising perspective for the adoption of highly resolved fUS approaches for the adult human brain. We combined ultrafast sensitive Doppler with contrast-enhanced ultrasound imaging. We retrieved highly-resolved neurovascular transcranial maps with contrast agents. The presence of microbubbles compensates for the attenuation from the skull. fUS is sensitive to the local hyperemia in the rat brain through the skull with microbubbles. Transcranial fUS imaging allows non-invasive functional brain studies in rodents.
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Affiliation(s)
- Claudia Errico
- INSERM, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; ESPCI ParisTech, PSL Research University, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; CNRS, Institut Langevin, 1 rue Jussieu, 75005, Paris, France
| | - Bruno-Félix Osmanski
- INSERM, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; ESPCI ParisTech, PSL Research University, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; CNRS, Institut Langevin, 1 rue Jussieu, 75005, Paris, France
| | - Sophie Pezet
- CNRS, UMR 8249, 10 rue Vauquelin, 75005 Paris, France; Brain Plasticity Unit, ESPCI-ParisTech, PSL Research University 10 rue Vauquelin, 75005 Paris, France
| | - Olivier Couture
- INSERM, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; ESPCI ParisTech, PSL Research University, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; CNRS, Institut Langevin, 1 rue Jussieu, 75005, Paris, France
| | - Zsolt Lenkei
- CNRS, UMR 8249, 10 rue Vauquelin, 75005 Paris, France; Brain Plasticity Unit, ESPCI-ParisTech, PSL Research University 10 rue Vauquelin, 75005 Paris, France
| | - Mickael Tanter
- INSERM, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; ESPCI ParisTech, PSL Research University, Institut Langevin, 1 rue Jussieu, 75005, Paris, France; CNRS, Institut Langevin, 1 rue Jussieu, 75005, Paris, France.
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146
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Schwiedrzik CM, Zarco W, Everling S, Freiwald WA. Face Patch Resting State Networks Link Face Processing to Social Cognition. PLoS Biol 2015; 13:e1002245. [PMID: 26348613 PMCID: PMC4562659 DOI: 10.1371/journal.pbio.1002245] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 08/05/2015] [Indexed: 01/09/2023] Open
Abstract
Faces transmit a wealth of social information. How this information is exchanged between face-processing centers and brain areas supporting social cognition remains largely unclear. Here we identify these routes using resting state functional magnetic resonance imaging in macaque monkeys. We find that face areas functionally connect to specific regions within frontal, temporal, and parietal cortices, as well as subcortical structures supporting emotive, mnemonic, and cognitive functions. This establishes the existence of an extended face-recognition system in the macaque. Furthermore, the face patch resting state networks and the default mode network in monkeys show a pattern of overlap akin to that between the social brain and the default mode network in humans: this overlap specifically includes the posterior superior temporal sulcus, medial parietal, and dorsomedial prefrontal cortex, areas supporting high-level social cognition in humans. Together, these results reveal the embedding of face areas into larger brain networks and suggest that the resting state networks of the face patch system offer a new, easily accessible venue into the functional organization of the social brain and into the evolution of possibly uniquely human social skills. An analysis of the functional connectivity of regions of the monkey brain involved in face recognition suggests substrates for the cognitive, mnemonic, emotive, and motoric impact of faces, revealing striking similarities to the human brain, and implying a deep evolutionary heritage of even the most high-level sociocognitive functions. Primates have evolved to transmit social information through their faces. Where and how the brain processes facial information received by the eyes we now understand quite well. Yet we do not know how this information is made available to other brain areas so that a face can evoke an emotion, activate the memory of a person, or draw attention. Here, to identify brain regions interacting with face areas, we performed whole-brain imaging in macaque monkeys, whose face-processing system we know best. We find that the core face-processing areas are connected to several other brain areas supporting socially, emotionally, and cognitively relevant functions. Together, they form an extended face-processing network, similar to what has been proposed for humans. This extended face-processing network intersects with a second large-scale network, the so-called “default mode network”, in a pattern stunningly similar to that in the human brain. This intersection identifies selectively those brain regions that implement the most high-level forms of social cognition, such as understanding others’ thoughts and feelings. Thus, the results of this novel approach to understanding the functional organization of the social brain point to a deep evolutionary heritage of human abilities for social cognition.
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Affiliation(s)
- Caspar M. Schwiedrzik
- Laboratory of Neural Systems, The Rockefeller University, New York, New York, United States of America
- * E-mail: (CMS); (WAF)
| | - Wilbert Zarco
- Laboratory of Neural Systems, The Rockefeller University, New York, New York, United States of America
| | - Stefan Everling
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Winrich A. Freiwald
- Laboratory of Neural Systems, The Rockefeller University, New York, New York, United States of America
- * E-mail: (CMS); (WAF)
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147
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Maloney TC, Tenney JR, Szaflarski JP, Vannest J. Simultaneous Electroencephalography and Functional Magnetic Resonance Imaging and the Identification of Epileptic Networks in Children. JOURNAL OF PEDIATRIC EPILEPSY 2015; 4:174-183. [PMID: 26744634 DOI: 10.1055/s-0035-1559812] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
EEG/fMRI takes advantage of the high temporal resolution of EEG in combination with the high spatial resolution of fMRI. These features make it particularly applicable to the study of epilepsy in which the event duration (e.g., interictal epileptiform discharges) is short, typically less than 200 milliseconds. Interictal or ictal discharges can be identified on EEG and be used for source localization in fMRI analyses. The acquisition of simultaneous EEG/fMRI involves the use of specialized EEG hardware that is safe in the MR environment and comfortable to the participant. Advanced data analysis approaches such as independent component analysis conducted alone or sometimes combined with other, e.g., Granger Causality or "sliding window" analyses are currently thought to be most appropriate for EEG/fMRI data. These approaches make it possible to identify networks of brain regions associated with ictal and/or interictal events allowing examination of the mechanisms critical for generation and propagation through these networks. After initial evaluation in adults, EEG/fMRI has been applied to the examination of the pediatric epilepsy syndromes including Childhood Absence Epilepsy, Benign Epilepsy with Centrotemporal Spikes (BECTS), Dravet Syndrome, and Lennox-Gastaut Syndrome. Results of EEG/fMRI studies suggest that the hemodynamic response measured by fMRI may have a different shape in response to epileptic events compared to the response to external stimuli; this may be especially true in the developing brain. Thus, the main goal of this review is to provide an overview of the pediatric applications of EEG/fMRI and its associated findings up until this point.
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148
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The hemodynamic response to somatosensory stimulation in mice depends on the anesthetic used: Implications on analysis of mouse fMRI data. Neuroimage 2015; 116:40-9. [DOI: 10.1016/j.neuroimage.2015.05.013] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 04/30/2015] [Accepted: 05/05/2015] [Indexed: 11/23/2022] Open
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149
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Tang J, Xi L, Zhou J, Huang H, Zhang T, Carney PR, Jiang H. Noninvasive high-speed photoacoustic tomography of cerebral hemodynamics in awake-moving rats. J Cereb Blood Flow Metab 2015; 35:1224-32. [PMID: 26082016 PMCID: PMC4527999 DOI: 10.1038/jcbfm.2015.138] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/10/2015] [Accepted: 05/06/2015] [Indexed: 11/09/2022]
Abstract
We present a noninvasive method of photoacoustic tomography (PAT) for imaging cerebral hemodynamics in awake-moving rats. The wearable PAT (wPAT) system has a size of 15 mm in height and 33 mm in diameter, and a weight of ~8 g (excluding cabling). The wPAT achieved an imaging rate of 3.33 frames/s with a lateral resolution of 243 μm. Animal experiments were designed to show wPAT feasibility for imaging cerebral hemodynamics on awake-moving animals. Results showed that the cerebral oxy-hemoglobin and deoxy-hemoglobin changed significantly in response to hyperoxia; and, after the injection of pentylenetetrazol (PTZ), cerebral blood volume changed faster over time and larger in amplitude for rats in awake-moving state compared with rats under anesthesia. By providing a light-weight, high-resolution technology for in vivo monitoring of cerebral hemodynamics in awake-behaving animals, it will be possible to develop a comprehensive understanding on how activity alters hemodynamics in normal and diseased states.
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Affiliation(s)
- Jianbo Tang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Lei Xi
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Junli Zhou
- Department of Pediatrics, University of Florida, Gainesville, Florida, USA
| | - Hua Huang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Tao Zhang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Paul R Carney
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
- Department of Pediatrics, University of Florida, Gainesville, Florida, USA
- Department of Neurology, University of Florida, Gainesville, Florida, USA
- Department of Neuroscience, University of Florida, Gainesville, Florida, USA
| | - Huabei Jiang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
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150
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Comparison of stimulus-evoked cerebral hemodynamics in the awake mouse and under a novel anesthetic regime. Sci Rep 2015. [PMID: 26218081 PMCID: PMC4517464 DOI: 10.1038/srep12621] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neural activity is closely followed by a localised change in cerebral blood flow, a process termed neurovascular coupling. These hemodynamic changes form the basis of contrast in functional magnetic resonance imaging (fMRI) and are used as a correlate for neural activity. Anesthesia is widely employed in animal fMRI and neurovascular studies, however anesthetics are known to profoundly affect neural and vascular physiology, particularly in mice. Therefore, we investigated the efficacy of a novel ‘modular’ anesthesia that combined injectable (fentanyl-fluanisone/midazolam) and volatile (isoflurane) anesthetics in mice. To characterize sensory-evoked cortical hemodynamic responses, we used optical imaging spectroscopy to produce functional maps of changes in tissue oxygenation and blood volume in response to mechanical whisker stimulation. Following fine-tuning of the anesthetic regime, stimulation elicited large and robust hemodynamic responses in the somatosensory cortex, characterized by fast arterial activation, increases in total and oxygenated hemoglobin, and decreases in deoxygenated hemoglobin. Overall, the magnitude and speed of evoked hemodynamic responses under anesthesia resembled those in the awake state, indicating that the novel anesthetic combination significantly minimizes the impact of anesthesia. Our findings have broad implications for both neurovascular research and longitudinal fMRI studies that increasingly require the use of genetically engineered mice.
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