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Li S, Lv P, He M, Zhang W, Liu J, Gong Y, Wang T, Gong Q, Ji Y, Lui S. Cerebral regional and network characteristics in asthma patients: a resting-state fMRI study. Front Med 2020; 14:792-801. [PMID: 32270434 DOI: 10.1007/s11684-020-0745-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 12/18/2019] [Indexed: 02/08/2023]
Abstract
Asthma is a serious health problem that involves not only the respiratory system but also the central nervous system. Previous studies identified either regional or network alterations in patients with asthma, but inconsistent results were obtained. A key question remains unclear: are the regional and neural network deficits related or are they two independent characteristics in asthma? Answering this question is the aim of this study. By collecting resting-state functional magnetic resonance imaging from 39 patients with asthma and 40 matched health controls, brain functional measures including regional activity (amplitude of low-frequency fluctuations) and neural network function (degree centrality (DC) and functional connectivity) were calculated to systematically characterize the functional alterations. Patients exhibited regional abnormities in the left angular gyrus, right precuneus, and inferior temporal gyrus within the default mode network. Network abnormalities involved both the sensorimotor network and visual network with key regions including the superior frontal gyrus and occipital lobes. Altered DC in the lingual gyrus was correlated with the degree of airway obstruction. This study elucidated different patterns of regional and network changes, thereby suggesting that the two parameters reflect different brain characteristics of asthma. These findings provide evidence for further understanding the potential cerebral alterations in the pathophysiology of asthma.
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Affiliation(s)
- Siyi Li
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Peilin Lv
- Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Min He
- Department of Respiratory Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Wenjing Zhang
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Jieke Liu
- Department of Radiology, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, 610041, China
| | - Yao Gong
- Department of Geriatric Psychiatry, The Fourth People's Hospital of Chengdu, Chengdu, 610036, China
| | - Ting Wang
- Department of Respiratory Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Qiyong Gong
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Yulin Ji
- Department of Respiratory Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Su Lui
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, 610041, China.
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An Unexpected Dependence of Cortical Depth in Shaping Neural Responsiveness and Selectivity in Mouse Visual Cortex. eNeuro 2020; 7:ENEURO.0497-19.2020. [PMID: 32051142 PMCID: PMC7092962 DOI: 10.1523/eneuro.0497-19.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 12/23/2019] [Accepted: 01/31/2020] [Indexed: 01/04/2023] Open
Abstract
Two-photon imaging studies in mouse primary visual cortex (V1) consistently report that around half of the neurons respond to oriented grating stimuli. However, in cats and primates, nearly all neurons respond to such stimuli. Here we show that mouse V1 responsiveness and selectivity strongly depends on neuronal depth. Moving from superficial layer 2 down to layer 4, the percentage of visually responsive neurons nearly doubled, ultimately reaching levels similar to what is seen in other species. Over this span, the amplitude of neuronal responses also doubled. Moreover, stimulus selectivity was also modulated, not only with depth but also with response amplitude. Specifically, we found that orientation and direction selectivity were greater in stronger responding neurons, but orientation selectivity decreased with depth whereas direction selectivity increased. Importantly, these depth-dependent trends were found not just between layer 2/3 and layer 4 but at different depths within layer 2/3 itself. Thus, neuronal depth is an important factor to consider when pooling neurons for population analyses. Furthermore, the inability to drive the majority of cells in superficial layer 2/3 of mouse V1 with grating stimuli indicates that there may be fundamental differences in the micro-circuitry and role of V1 between rodents and other mammals.
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Morante-Redolat JM, Fariñas I. NO Hemodynamic Speed Limit for Hippocampal Neurogenesis. Neuron 2020; 103:752-754. [PMID: 31487523 DOI: 10.1016/j.neuron.2019.08.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In this issue of Neuron, Shen et al. (2019) address the coupling between vascular flow and neurogenic output, showing that pre-existing hippocampal circuits modulate hemodynamics in a NO-dependent manner to promote IGF-1-dependent survival of newly generated neuroblasts.
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Affiliation(s)
- José Manuel Morante-Redolat
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), and Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, 46100 Burjassot, Spain
| | - Isabel Fariñas
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), and Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, 46100 Burjassot, Spain.
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Coelho‐Santos V, Shih AY. Postnatal development of cerebrovascular structure and the neurogliovascular unit. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2020; 9:e363. [PMID: 31576670 PMCID: PMC7027551 DOI: 10.1002/wdev.363] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 12/22/2022]
Abstract
The unceasing metabolic demands of brain function are supported by an intricate three-dimensional network of arterioles, capillaries, and venules, designed to effectively distribute blood to all neurons and to provide shelter from harmful molecules in the blood. The development and maturation of this microvasculature involves a complex interplay between endothelial cells with nearly all other brain cell types (pericytes, astrocytes, microglia, and neurons), orchestrated throughout embryogenesis and the first few weeks after birth in mice. Both the expansion and regression of vascular networks occur during the postnatal period of cerebrovascular remodeling. Pial vascular networks on the brain surface are dense at birth and are then selectively pruned during the postnatal period, with the most dramatic changes occurring in the pial venular network. This is contrasted to an expansion of subsurface capillary networks through the induction of angiogenesis. Concurrent with changes in vascular structure, the integration and cross talk of neurovascular cells lead to establishment of blood-brain barrier integrity and neurovascular coupling to ensure precise control of macromolecular passage and metabolic supply. While we still possess a limited understanding of the rules that control cerebrovascular development, we can begin to assemble a view of how this complex process evolves, as well as identify gaps in knowledge for the next steps of research. This article is categorized under: Nervous System Development > Vertebrates: Regional Development Vertebrate Organogenesis > Musculoskeletal and Vascular Nervous System Development > Vertebrates: General Principles.
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Affiliation(s)
- Vanessa Coelho‐Santos
- Center for Developmental Biology and Regenerative MedicineSeattle Children's Research InstituteSeattleWashington
- Department of PediatricsUniversity of WashingtonSeattleWashington
| | - Andy Y. Shih
- Center for Developmental Biology and Regenerative MedicineSeattle Children's Research InstituteSeattleWashington
- Department of PediatricsUniversity of WashingtonSeattleWashington
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Zechariah A, Tran CHT, Hald BO, Sandow SL, Sancho M, Kim MSM, Fabris S, Tuor UI, Gordon GR, Welsh DG. Intercellular Conduction Optimizes Arterial Network Function and Conserves Blood Flow Homeostasis During Cerebrovascular Challenges. Arterioscler Thromb Vasc Biol 2020; 40:733-750. [PMID: 31826653 PMCID: PMC7058668 DOI: 10.1161/atvbaha.119.313391] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Cerebral arterial networks match blood flow delivery with neural activity. Neurovascular response begins with a stimulus and a focal change in vessel diameter, which by themselves is inconsequential to blood flow magnitude, until they spread and alter the contractile status of neighboring arterial segments. We sought to define the mechanisms underlying integrated vascular behavior and considered the role of intercellular electrical signaling in this phenomenon. Approach and Results: Electron microscopic and histochemical analysis revealed the structural coupling of cerebrovascular cells and the expression of gap junctional subunits at the cell interfaces, enabling intercellular signaling among vascular cells. Indeed, robust vasomotor conduction was detected in human and mice cerebral arteries after focal vessel stimulation: a response attributed to endothelial gap junctional communication, as its genetic alteration attenuated this behavior. Conducted responses were observed to ascend from the penetrating arterioles, influencing the contractile status of cortical surface vessels, in a simulated model of cerebral arterial network. Ascending responses recognized in vivo after whisker stimulation were significantly attenuated in mice with altered endothelial gap junctional signaling confirming that gap junctional communication drives integrated vessel responses. The diminishment in vascular communication also impaired the critical ability of the cerebral vasculature to maintain blood flow homeostasis and hence tissue viability after stroke. CONCLUSIONS Our findings highlight the integral role of intercellular electrical signaling in transcribing focal stimuli into coordinated changes in cerebrovascular contractile activity and expose, a hitherto unknown mechanism for flow regulation after stroke.
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Affiliation(s)
- Anil Zechariah
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Cam Ha T. Tran
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- Department of Physiology and Cell Biology, University of Nevada, Reno, Nevada, USA 89557
| | - Bjorn O. Hald
- Department of Neuroscience, Translational Neurobiology, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Shaun L. Sandow
- University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland 4558 Australia
| | - Maria Sancho
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Michelle Sun Mi Kim
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Sergio Fabris
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Ursula I. Tuor
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Grant R.J. Gordon
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Donald G. Welsh
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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56
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Chow BW, Nuñez V, Kaplan L, Granger AJ, Bistrong K, Zucker HL, Kumar P, Sabatini BL, Gu C. Caveolae in CNS arterioles mediate neurovascular coupling. Nature 2020; 579:106-110. [PMID: 32076269 PMCID: PMC7060132 DOI: 10.1038/s41586-020-2026-1] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 01/03/2020] [Indexed: 12/13/2022]
Abstract
Proper brain function depends on neurovascular coupling: neural activity rapidly increases local blood flow to meet moment-to-moment changes in regional brain energy demand1. Neurovascular coupling is the basis for functional brain imaging2, and its impairment is implicated in neurodegeneration1. The underlying molecular and cellular mechanisms of neurovascular coupling remain poorly understood. The conventional view is that neurons or astrocytes release vasodilatory factors that act directly on smooth muscle cells (SMC) to induce arterial dilation and increase local blood flow1. Here, using two-photon microscopy to image neural activity and vascular dynamics simultaneously in the barrel cortex of awake mice under whisker stimulation, we found that arteriolar endothelial cells (aECs) play an active role in mediating neurovascular coupling. We found that aECs, unlike other vascular segments of ECs in the CNS, have abundant caveolae. Acute genetic perturbations that eliminated caveolae in aECs, but not in neighboring SMCs, impaired neurovascular coupling. Strikingly, caveolae function in aECs is independent of the eNOS-mediated nitric oxide (NO) pathway. Ablation of both caveolae and eNOS completely abolished neurovascular coupling, whereas each single mutant exhibited partial impairment, revealing that caveolae-mediated pathway in aECs is a major contributor to neurovascular coupling. Our findings indicate that vasodilation is largely due to ECs that actively relay signals from the CNS to SMCs via a caveolae-dependent pathway.
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Affiliation(s)
- Brian W Chow
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Vicente Nuñez
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Luke Kaplan
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Adam J Granger
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Karina Bistrong
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Hannah L Zucker
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Payal Kumar
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Bernardo L Sabatini
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Chenghua Gu
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
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57
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Chen W, Park K, Pan Y, Koretsky AP, Du C. Interactions between stimuli-evoked cortical activity and spontaneous low frequency oscillations measured with neuronal calcium. Neuroimage 2020; 210:116554. [PMID: 31972283 DOI: 10.1016/j.neuroimage.2020.116554] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/07/2019] [Accepted: 01/14/2020] [Indexed: 02/06/2023] Open
Abstract
Spontaneous brain activity has been widely used to map brain connectivity. The interactions between task-evoked brain responses and the spontaneous cortical oscillations, especially within the low frequency range of ~0.1 Hz, are not fully understood. Trial-to-trial variabilities in brain's response to sensory stimuli and the ability for brain to detect under noisy conditions suggest an appreciable impact of the brain state. Using a multimodality imaging platform, we simultaneously imaged neuronal Ca2+ and cerebral hemodynamics at baseline and in response to single-pulse forepaw stimuli in rat's somatosensory cortex. The high sensitivity of this system enables detection of responses to very weak and strong stimuli and real time determination of low frequency oscillations without averaging. Results show that the ongoing neuronal oscillations inversely modulate Ca2+ transients evoked by sensory stimuli. High intensity stimuli reset the spontaneous neuronal oscillations to an unpreferable excitability following the stimulus. Cerebral hemodynamic responses also inversely interact with the spontaneous hemodynamic oscillations, correlating with the neuronal Ca2+ transient changes. The results reveal competing interactions between spontaneous oscillations and stimulation-evoked brain activities in somatosensory cortex and the resultant hemodynamics.
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Affiliation(s)
- Wei Chen
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Kicheon Park
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Yingtian Pan
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Congwu Du
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA.
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58
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Valley MT, Moore MG, Zhuang J, Mesa N, Castelli D, Sullivan D, Reimers M, Waters J. Separation of hemodynamic signals from GCaMP fluorescence measured with wide-field imaging. J Neurophysiol 2020; 123:356-366. [DOI: 10.1152/jn.00304.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Wide-field calcium imaging is often used to measure brain dynamics in behaving mice. With a large field of view and a high sampling rate, wide-field imaging can monitor activity from several distant cortical areas simultaneously, revealing cortical interactions. Interpretation of wide-field images is complicated, however, by the absorption of light by hemoglobin, which can substantially affect the measured fluorescence. One approach to separating hemodynamics and calcium signals is to use multiwavelength backscatter recordings to measure light absorption by hemoglobin. Following this approach, we develop a spatially detailed regression-based method to estimate hemodynamics. This Spatial Model is based on a linear form of the Beer–Lambert relationship but is fit at every pixel in the image and does not rely on the estimation of physical parameters. In awake mice of three transgenic lines, the Spatial Model offers improved separation of hemodynamics and changes in GCaMP fluorescence. The improvement is pronounced near blood vessels and, in contrast with the Beer–Lambert equations, can remove vascular artifacts along the sagittal midline and in general permits more accurate fluorescence-based determination of neuronal activity across the cortex. NEW & NOTEWORTHY This paper addresses a well-known and strong source of contamination in wide-field calcium-imaging data: hemodynamics. To guide researchers toward the best method to separate calcium signals from hemodynamics, we compare the performance of several methods in three commonly used mouse lines and present a novel regression model that outperforms the other techniques we consider.
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Affiliation(s)
- M. T. Valley
- Allen Institute for Brain Science, Seattle, Washington
| | - M. G. Moore
- Neuroscience Program and Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, Michigan
| | - J. Zhuang
- Allen Institute for Brain Science, Seattle, Washington
| | - N. Mesa
- Allen Institute for Brain Science, Seattle, Washington
| | - D. Castelli
- Allen Institute for Brain Science, Seattle, Washington
| | - D. Sullivan
- Allen Institute for Brain Science, Seattle, Washington
| | - M. Reimers
- Neuroscience Program and Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, Michigan
| | - J. Waters
- Allen Institute for Brain Science, Seattle, Washington
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59
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Gu X, Chen W, Volkow ND, Koretsky AP, Du C, Pan Y. Synchronized Astrocytic Ca 2+ Responses in Neurovascular Coupling during Somatosensory Stimulation and for the Resting State. Cell Rep 2019; 23:3878-3890. [PMID: 29949771 PMCID: PMC7469112 DOI: 10.1016/j.celrep.2018.05.091] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 04/05/2018] [Accepted: 05/27/2018] [Indexed: 02/08/2023] Open
Abstract
The role of astrocytes in neurovascular coupling (NVC) is unclear. Here, we applied a multimodality imaging approach to concomitantly measure synchronized neuronal or astrocytic Ca2+ and hemodynamic changes in the mouse somatosensory cortex at rest and during sensory electrical stimulation. Strikingly, we found that low-frequency stimulation (0.3-1 Hz), which consistently evokes fast neuronal Ca2+ transients (6.0 ± 2.7 ms latency) that always precede vascular responses, does not always elicit astrocytic Ca2+ transients (313 ± 65 ms latency). However, the magnitude of the hemodynamic response is increased when astrocytic transients occur, suggesting a facilitatory role of astrocytes in NVC. High-frequency stimulation (5-10 Hz) consistently evokes a large, delayed astrocytic Ca2+ accumulation (3.48 ± 0.09 s latency) that is temporarily associated with vasoconstriction, suggesting a role for astrocytes in resetting NVC. At rest, neuronal, but not astrocytic, Ca2+ fluctuations correlate with hemodynamic low-frequency oscillations. Taken together, these results support a role for astrocytes in modulating, but not triggering, NVC.
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Affiliation(s)
- Xiaochun Gu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA; Jiangsu Key Laboratory of Molecular and Functional Imaging, Key Laboratory of Developmental Genes and Human Diseases, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, #87 Dingjiaqiao Road, Nanjing 210009, China
| | - Wei Chen
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nora D Volkow
- National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20857, USA
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Congwu Du
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
| | - Yingtian Pan
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
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60
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Meigel FJ, Cha P, Brenner MP, Alim K. Robust Increase in Supply by Vessel Dilation in Globally Coupled Microvasculature. PHYSICAL REVIEW LETTERS 2019; 123:228103. [PMID: 31868401 DOI: 10.1103/physrevlett.123.228103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Indexed: 06/10/2023]
Abstract
Neuronal activity induces changes in blood flow by locally dilating vessels in the brain microvasculature. How can the local dilation of a single vessel increase flow-based metabolite supply, given that flows are globally coupled within microvasculature? Solving the supply dynamics for rat brain microvasculature, we find one parameter regime to dominate physiologically. This regime allows for robust increase in supply independent of the position in the network, which we explain analytically. We show that local coupling of vessels promotes spatially correlated increased supply by dilation.
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Affiliation(s)
- Felix J Meigel
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Peter Cha
- John A. Paulson School of Engineering and Applied Sciences and Kavli Institute for Bionano Science and Technology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Michael P Brenner
- John A. Paulson School of Engineering and Applied Sciences and Kavli Institute for Bionano Science and Technology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Karen Alim
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- Physik-Department, Technische Universität München, 85748 Garching, Germany
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61
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Laminar specific fMRI reveals directed interactions in distributed networks during language processing. Proc Natl Acad Sci U S A 2019; 116:21185-21190. [PMID: 31570628 DOI: 10.1073/pnas.1907858116] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Interactions between top-down and bottom-up information streams are integral to brain function but challenging to measure noninvasively. Laminar resolution, functional MRI (lfMRI) is sensitive to depth-dependent properties of the blood oxygen level-dependent (BOLD) response, which can be potentially related to top-down and bottom-up signal contributions. In this work, we used lfMRI to dissociate the top-down and bottom-up signal contributions to the left occipitotemporal sulcus (LOTS) during word reading. We further demonstrate that laminar resolution measurements could be used to identify condition-specific distributed networks on the basis of whole-brain connectivity patterns specific to the depth-dependent BOLD signal. The networks corresponded to top-down and bottom-up signal pathways targeting the LOTS during word reading. We show that reading increased the top-down BOLD signal observed in the deep layers of the LOTS and that this signal uniquely related to the BOLD response in other language-critical regions. These results demonstrate that lfMRI can reveal important patterns of activation that are obscured at standard resolution. In addition to differences in activation strength as a function of depth, we also show meaningful differences in the interaction between signals originating from different depths both within a region and with the rest of the brain. We thus show that lfMRI allows the noninvasive measurement of directed interaction between brain regions and is capable of resolving different connectivity patterns at submillimeter resolution, something previously considered to be exclusively in the domain of invasive recordings.
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62
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Whole-Brain Functional Ultrasound Imaging Reveals Brain Modules for Visuomotor Integration. Neuron 2019; 100:1241-1251.e7. [PMID: 30521779 PMCID: PMC6292977 DOI: 10.1016/j.neuron.2018.11.031] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 09/05/2018] [Accepted: 11/16/2018] [Indexed: 11/22/2022]
Abstract
Large numbers of brain regions are active during behaviors. A high-resolution, brain-wide activity map could identify brain regions involved in specific behaviors. We have developed functional ultrasound imaging to record whole-brain activity in behaving mice at a resolution of ∼100 μm. We detected 87 active brain regions during visual stimulation that evoked the optokinetic reflex, a visuomotor behavior that stabilizes the gaze both horizontally and vertically. Using a genetic mouse model of congenital nystagmus incapable of generating the horizontal reflex, we identified a subset of regions whose activity was reflex dependent. By blocking eye motion in control animals, we further separated regions whose activity depended on the reflex’s motor output. Remarkably, all reflex-dependent but eye motion-independent regions were located in the thalamus. Our work identifies functional modules of brain regions involved in sensorimotor integration and provides an experimental approach to monitor whole-brain activity of mice in normal and disease states. Functional ultrasound enables imaging whole-brain activity during mouse behavior Activity in 87 brain regions are modulated during the optokinetic reflex Reflex-related regions were identified by perturbing retinal direction selectivity A subset of these regions, all in the thalamus, are independent of eye motion
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63
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Merkle CW, Zhu J, Bernucci MT, Srinivasan VJ. Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo. Neuroimage 2019; 202:116067. [PMID: 31394180 DOI: 10.1016/j.neuroimage.2019.116067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/01/2019] [Accepted: 08/01/2019] [Indexed: 12/18/2022] Open
Abstract
Studies of flow-metabolism coupling often presume that microvessel architecture is a surrogate for blood flow. To test this assumption, we introduce an in vivo Dynamic Contrast Optical Coherence Tomography (DyC-OCT) method to quantify layer-resolved microvascular blood flow and volume across the full depth of the mouse neocortex, where the angioarchitecture has been previously described. First, we cross-validate average DyC-OCT cortical flow against conventional Doppler OCT flow. Next, with laminar DyC-OCT, we discover that layer 4 consistently exhibits the highest microvascular blood flow, approximately two-fold higher than the outer cortical layers. While flow differences between layers are well-explained by microvascular volume and density, flow differences between subjects are better explained by transit time. Finally, from layer-resolved tracer enhancement, we also infer that microvascular hematocrit increases in deep cortical layers, consistent with predictions of plasma skimming. Altogether, our results show that while the cortical blood supply derives mainly from the pial surface, laminar hemodynamics ensure that the energetic needs of individual cortical layers are met. The laminar trends reported here provide data that links predictions based on the cortical angioarchitecture to cerebrovascular physiology in vivo.
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Affiliation(s)
- Conrad W Merkle
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Jun Zhu
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Marcel T Bernucci
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Vivek J Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA; Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, CA, 95817, USA.
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64
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Non-BOLD contrast for laminar fMRI in humans: CBF, CBV, and CMRO2. Neuroimage 2019; 197:742-760. [DOI: 10.1016/j.neuroimage.2017.07.041] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 07/10/2017] [Accepted: 07/19/2017] [Indexed: 12/22/2022] Open
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65
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Heartbeat-evoked cortical responses: Underlying mechanisms, functional roles, and methodological considerations. Neuroimage 2019; 197:502-511. [DOI: 10.1016/j.neuroimage.2019.04.081] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/29/2019] [Accepted: 04/30/2019] [Indexed: 11/24/2022] Open
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66
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Self MW, van Kerkoerle T, Goebel R, Roelfsema PR. Benchmarking laminar fMRI: Neuronal spiking and synaptic activity during top-down and bottom-up processing in the different layers of cortex. Neuroimage 2019. [DOI: 10.1016/j.neuroimage.2017.06.045] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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67
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Drew PJ. Vascular and neural basis of the BOLD signal. Curr Opin Neurobiol 2019; 58:61-69. [PMID: 31336326 DOI: 10.1016/j.conb.2019.06.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 06/22/2019] [Indexed: 12/26/2022]
Abstract
Neural activity in the brain is usually coupled to increases in local cerebral blood flow, leading to the increase in oxygenation that generates the BOLD fMRI signal. Recent work has begun to elucidate the vascular and neural mechanisms underlying the BOLD signal. The dilatory response is distributed throughout the vascular network. Arteries actively dilate within a second following neural activity increases, while venous distensions are passive and have a time course that last tens of seconds. Vasodilation, and thus local blood flow, is controlled by the activity of both neurons and astrocytes via multiple different pathways. The relationship between sensory-driven neural activity and the vascular dynamics in sensory areas are well-captured with a linear convolution model. However, depending on the behavioral state or brain region, the coupling between neural activity and hemodynamic signals can be weak or even inverted.
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Affiliation(s)
- Patrick J Drew
- Departments of Engineering Science and Mechanics, Biomedical Engineering and Neurosurgery, Pennsylvania State University, University Park, PA 16802, United States.
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68
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van Alst TM, Wachsmuth L, Datunashvili M, Albers F, Just N, Budde T, Faber C. Anesthesia differentially modulates neuronal and vascular contributions to the BOLD signal. Neuroimage 2019; 195:89-103. [DOI: 10.1016/j.neuroimage.2019.03.057] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 03/06/2019] [Accepted: 03/25/2019] [Indexed: 11/27/2022] Open
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69
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Shen J, Wang D, Wang X, Gupta S, Ayloo B, Wu S, Prasad P, Xiong Q, Xia J, Ge S. Neurovascular Coupling in the Dentate Gyrus Regulates Adult Hippocampal Neurogenesis. Neuron 2019; 103:878-890.e3. [PMID: 31257104 DOI: 10.1016/j.neuron.2019.05.045] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 04/25/2019] [Accepted: 05/29/2019] [Indexed: 12/11/2022]
Abstract
Newborn dentate granule cells (DGCs) are continuously generated in the adult brain. The mechanism underlying how the adult brain governs hippocampal neurogenesis remains poorly understood. In this study, we investigated how coupling of pre-existing neurons to the cerebrovascular system regulates hippocampal neurogenesis. Using a new in vivo imaging method in freely moving mice, we found that hippocampus-engaged behaviors, such as exploration in a novel environment, rapidly increased microvascular blood-flow velocity in the dentate gyrus. Importantly, blocking this exploration-elevated blood flow dampened experience-induced hippocampal neurogenesis. By imaging the neurovascular niche in combination with chemogenetic manipulation, we revealed that pre-existing DGCs actively regulated microvascular blood flow. This neurovascular coupling was linked by parvalbumin-expressing interneurons, primarily through nitric-oxide signaling. Further, we showed that insulin growth factor 1 signaling participated in functional hyperemia-induced neurogenesis. Together, our findings revealed a neurovascular coupling network that regulates experience-induced neurogenesis in the adult brain.
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Affiliation(s)
- Jia Shen
- The Program of Genetics, SUNY at Stony Brook, Stony Brook, NY 11794, USA; Department of Neurobiology & Behavior, SUNY at Stony Brook, Stony Brook, NY 11794, USA
| | - Depeng Wang
- Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - Xinxing Wang
- Department of Neurobiology & Behavior, SUNY at Stony Brook, Stony Brook, NY 11794, USA
| | - Shashank Gupta
- Department of Neurobiology & Behavior, SUNY at Stony Brook, Stony Brook, NY 11794, USA
| | - Bhargav Ayloo
- Department of Neurobiology & Behavior, SUNY at Stony Brook, Stony Brook, NY 11794, USA
| | - Song Wu
- Department of Applied Mathematics and Statistics, SUNY at Stony Brook, Stony Brook, NY 11794, USA
| | - Paras Prasad
- Institute for Lasers, Photonics and Biophotonics and the Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - Qiaojie Xiong
- Department of Neurobiology & Behavior, SUNY at Stony Brook, Stony Brook, NY 11794, USA.
| | - Jun Xia
- Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260, USA.
| | - Shaoyu Ge
- Department of Neurobiology & Behavior, SUNY at Stony Brook, Stony Brook, NY 11794, USA.
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70
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Liu C, Liao J, Chen L, Chen J, Ding R, Gong X, Cui C, Pang Z, Zheng W, Song L. The integrated high-resolution reflection-mode photoacoustic and fluorescence confocal microscopy. PHOTOACOUSTICS 2019; 14:12-18. [PMID: 30923675 PMCID: PMC6423349 DOI: 10.1016/j.pacs.2019.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 02/13/2019] [Accepted: 02/20/2019] [Indexed: 05/05/2023]
Abstract
A dual modality microscopy with the highest imaging resolution reported so far based on reflection-mode photoacoustic and confocal fluorescence is presented in this study. The unique design of the imaging head of the microscope makes it highly convenient for scalable high-resolution imaging by simply switching the optical objectives. The submicron resolution performance of the system is demonstrated via in vivo imaging of zebrafish, normal mouse ear, and a xenograft tumor model inoculated in the mouse ear. The imaging results confirm that the presented dual-modality microscopy imaging system could play a vital role in observing model organism, studying tumor angiogenesis and assessment of antineoplastic drugs.
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Affiliation(s)
- Chengbo Liu
- Research Laboratory for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Jiuling Liao
- Research Laboratory for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Longchao Chen
- Guangzhou SENVIV Technology Co. Ltd, Guangzhou 510006, China
| | - Jianhua Chen
- Guangzhou SENVIV Technology Co. Ltd, Guangzhou 510006, China
| | - Rubo Ding
- Guangzhou SENVIV Technology Co. Ltd, Guangzhou 510006, China
| | - Xiaojing Gong
- Research Laboratory for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Caimei Cui
- Guangzhou SENVIV Technology Co. Ltd, Guangzhou 510006, China
| | - Zhiqiang Pang
- Guangzhou SENVIV Technology Co. Ltd, Guangzhou 510006, China
| | - Wei Zheng
- Research Laboratory for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- Corresponding authors.
| | - Liang Song
- Research Laboratory for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- Corresponding authors.
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71
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Hughes AE, Greenwood JA, Finlayson NJ, Schwarzkopf DS. Population receptive field estimates for motion-defined stimuli. Neuroimage 2019; 199:245-260. [PMID: 31158480 PMCID: PMC6693563 DOI: 10.1016/j.neuroimage.2019.05.068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 05/27/2019] [Indexed: 11/12/2022] Open
Abstract
The processing of motion changes throughout the visual hierarchy, from spatially restricted ‘local motion’ in early visual cortex to more complex large-field ‘global motion’ at later stages. Here we used functional magnetic resonance imaging (fMRI) to examine spatially selective responses in these areas related to the processing of random-dot stimuli defined by differences in motion. We used population receptive field (pRF) analyses to map retinotopic cortex using bar stimuli comprising coherently moving dots. In the first experiment, we used three separate background conditions: no background dots (dot-defined bar-only), dots moving coherently in the opposite direction to the bar (kinetic boundary) and dots moving incoherently in random directions (global motion). Clear retinotopic maps were obtained for the bar-only and kinetic-boundary conditions across visual areas V1–V3 and in higher dorsal areas. For the global-motion condition, retinotopic maps were much weaker in early areas and became clear only in higher areas, consistent with the emergence of global-motion processing throughout the visual hierarchy. However, in a second experiment we demonstrate that this pattern is not specific to motion-defined stimuli, with very similar results for a transparent-motion stimulus and a bar defined by a static low-level property (dot size) that should have driven responses particularly in V1. We further exclude explanations based on stimulus visibility by demonstrating that the observed differences in pRF properties do not follow the ability of observers to localise or attend to these bar elements. Rather, our findings indicate that dorsal extrastriate retinotopic maps may primarily be determined by the visibility of the neural responses to the bar relative to the background response (i.e. neural signal-to-noise ratios) and suggests that claims about stimulus selectivity from pRF experiments must be interpreted with caution.
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Affiliation(s)
- Anna E Hughes
- Experimental Psychology, University College London, 26 Bedford Way, London, WC1H 0AP, UK.
| | - John A Greenwood
- Experimental Psychology, University College London, 26 Bedford Way, London, WC1H 0AP, UK
| | - Nonie J Finlayson
- Experimental Psychology, University College London, 26 Bedford Way, London, WC1H 0AP, UK
| | - D Samuel Schwarzkopf
- Experimental Psychology, University College London, 26 Bedford Way, London, WC1H 0AP, UK
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72
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Yi G, Grill WM. Average firing rate rather than temporal pattern determines metabolic cost of activity in thalamocortical relay neurons. Sci Rep 2019; 9:6940. [PMID: 31061521 PMCID: PMC6502890 DOI: 10.1038/s41598-019-43460-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 04/25/2019] [Indexed: 12/19/2022] Open
Abstract
Thalamocortical (TC) relay cells exhibit different temporal patterns of activity, including tonic mode and burst mode, to transmit sensory information to the cortex. Our aim was to quantify the metabolic cost of different temporal patterns of neural activity across a range of average firing rates. We used a biophysically-realistic model of a TC relay neuron to simulate tonic and burst patterns of firing. We calculated the metabolic cost by converting the calculated ion fluxes into the demand for ATP to maintain homeostasis of intracellular ion concentrations. Most energy was expended on reversing Na+ entry during action potentials and pumping Ca2+ out of the cell. Average firing rate determined the ATP cost across firing patterns by controlling the overall number of spikes. Varying intraburst frequency or spike number in each burst influenced the metabolic cost by altering the interactions of inward and outward currents on multiple timescales, but temporal pattern contributed substantially less to the metabolic demand of neural activity as compared to average firing rate. These predictions should be considered when interpreting findings of functional imaging studies that rely of estimates of neuronal metabolic demand, e.g., functional magnetic resonance imaging.
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Affiliation(s)
- Guosheng Yi
- Department of Biomedical Engineering, Duke University, Durham, NC, United States.,School of Electrical and Information Engineering, Tianjin University, Tianjin, China
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, United States. .,Department of Electrical and Computer Engineering, Duke University, Durham, NC, United States. .,Department of Neurobiology, Duke University School of Medicine, Durham, NC, United States. .,Department of Neurosurgery, Duke University School of Medicine, Durham, NC, United States.
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73
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Gottschalk S, Degtyaruk O, Mc Larney B, Rebling J, Hutter MA, Deán-Ben XL, Shoham S, Razansky D. Rapid volumetric optoacoustic imaging of neural dynamics across the mouse brain. Nat Biomed Eng 2019; 3:392-401. [PMID: 30992553 PMCID: PMC6825512 DOI: 10.1038/s41551-019-0372-9] [Citation(s) in RCA: 129] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 02/19/2019] [Indexed: 01/25/2023]
Abstract
Efforts to scale neuroimaging towards the direct visualization of mammalian brain-wide neuronal activity have faced major challenges. Although high-resolution optical imaging of the whole brain in small animals has been achieved ex vivo, the real-time and direct monitoring of large-scale neuronal activity remains difficult, owing to the performance gap between localized, largely invasive, optical microscopy of rapid, cellular-resolved neuronal activity and whole-brain macroscopy of slow haemodynamics and metabolism. Here, we demonstrate both ex vivo and non-invasive in vivo functional optoacoustic (OA) neuroimaging of mice expressing the genetically encoded calcium indicator GCaMP6f. The approach offers rapid, high-resolution three-dimensional snapshots of whole-brain neuronal activity maps using single OA excitations, and of stimulus-evoked slow haemodynamics and fast calcium activity in the presence of strong haemoglobin background absorption. By providing direct neuroimaging at depths and spatiotemporal resolutions superior to optical fluorescence imaging, functional OA neuroimaging bridges the gap between functional microscopy and whole-brain macroscopy.
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Affiliation(s)
- Sven Gottschalk
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
| | - Oleksiy Degtyaruk
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
| | - Benedict Mc Larney
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Faculty of Medicine, Technical University of Munich, Munich, Germany
| | - Johannes Rebling
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Faculty of Medicine, Technical University of Munich, Munich, Germany
- Faculty of Medicine, University of Zurich, Zurich, Switzerland
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland
- Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Magdalena Anastasia Hutter
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Department of Electrical and Computer Engineering, Technical University of Munich, Munich, Germany
| | - Xosé Luís Deán-Ben
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Faculty of Medicine, University of Zurich, Zurich, Switzerland
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland
- Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Shy Shoham
- Tech4Health Institute, New York University Langone Health, New York, NY, USA.
- Neuroscience Institute, New York University Langone Health, New York, NY, USA.
- Department of Ophthalmology, New York University Langone Health, New York, NY, USA.
| | - Daniel Razansky
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany.
- Faculty of Medicine, Technical University of Munich, Munich, Germany.
- Faculty of Medicine, University of Zurich, Zurich, Switzerland.
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
- Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland.
- Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland.
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74
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High-speed imaging of glutamate release with genetically encoded sensors. Nat Protoc 2019; 14:1401-1424. [PMID: 30988508 DOI: 10.1038/s41596-019-0143-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/22/2019] [Indexed: 11/08/2022]
Abstract
The strength of an excitatory synapse depends on its ability to release glutamate and on the density of postsynaptic receptors. Genetically encoded glutamate indicators (GEGIs) allow eavesdropping on synaptic transmission at the level of cleft glutamate to investigate properties of the release machinery in detail. Based on the sensor iGluSnFR, we recently developed accelerated versions of GEGIs that allow investigation of synaptic release during 100-Hz trains. Here, we describe the detailed procedures for design and characterization of fast iGluSnFR variants in vitro, transfection of pyramidal cells in organotypic hippocampal cultures, and imaging of evoked glutamate transients with two-photon laser-scanning microscopy. As the released glutamate spreads from a point source-the fusing vesicle-it is possible to localize the vesicle fusion site with a precision exceeding the optical resolution of the microscope. By using a spiral scan path, the temporal resolution can be increased to 1 kHz to capture the peak amplitude of fast iGluSnFR transients. The typical time frame for these experiments is 30 min per synapse.
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75
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Dizeux A, Gesnik M, Ahnine H, Blaize K, Arcizet F, Picaud S, Sahel JA, Deffieux T, Pouget P, Tanter M. Functional ultrasound imaging of the brain reveals propagation of task-related brain activity in behaving primates. Nat Commun 2019; 10:1400. [PMID: 30923310 PMCID: PMC6438968 DOI: 10.1038/s41467-019-09349-w] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 03/04/2019] [Indexed: 01/24/2023] Open
Abstract
Neuroimaging modalities such as MRI and EEG are able to record from the whole brain, but this comes at the price of either limited spatiotemporal resolution or limited sensitivity. Here, we show that functional ultrasound imaging (fUS) of the brain is able to assess local changes in cerebral blood volume during cognitive tasks, with sufficient temporal resolution to measure the directional propagation of signals. In two macaques, we observed an abrupt transient change in supplementary eye field (SEF) activity when animals were required to modify their behaviour associated with a change of saccade tasks. SEF activation could be observed in a single trial, without averaging. Simultaneous imaging of anterior cingulate cortex and SEF revealed a time delay in the directional functional connectivity of 0.27 ± 0.07 s and 0.9 ± 0.2 s for both animals. Cerebral hemodynamics of large brain areas can be measured at high spatiotemporal resolution using fUS. Neuroimaging modalities such as MRI and EEG are able to record brain activity, but spatiotemporal resolution and sensitivity are limited. Here, the authors show how a recently developed method, functional ultrasound imaging (fUS), can measure brain activation during cognitive tasks in primates.
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Affiliation(s)
- Alexandre Dizeux
- Physics for Medicine, ESPCI, INSERM, CNRS, PSL Research University, Paris, France.
| | - Marc Gesnik
- Physics for Medicine, ESPCI, INSERM, CNRS, PSL Research University, Paris, France
| | - Harry Ahnine
- INSERM 1127, CNRS 7225, Institut du Cerveau et de la Moelle épinière, Sorbonne Université, Paris, France
| | - Kevin Blaize
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France
| | - Fabrice Arcizet
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France
| | - Serge Picaud
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France
| | - José-Alain Sahel
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France.,Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Thomas Deffieux
- Physics for Medicine, ESPCI, INSERM, CNRS, PSL Research University, Paris, France
| | - Pierre Pouget
- INSERM 1127, CNRS 7225, Institut du Cerveau et de la Moelle épinière, Sorbonne Université, Paris, France.
| | - Mickael Tanter
- Physics for Medicine, ESPCI, INSERM, CNRS, PSL Research University, Paris, France.
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76
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van Mourik T, van der Eerden JPJM, Bazin PL, Norris DG. Laminar signal extraction over extended cortical areas by means of a spatial GLM. PLoS One 2019; 14:e0212493. [PMID: 30917123 PMCID: PMC6436691 DOI: 10.1371/journal.pone.0212493] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 02/05/2019] [Indexed: 01/06/2023] Open
Abstract
There is converging evidence that distinct neuronal processes leave distinguishable footprints in the laminar BOLD response. However, even though the achievable spatial resolution in functional MRI has much improved over the years, it is still challenging to separate signals arising from different cortical layers. In this work, we propose a new method to extract laminar signals. We use a spatial General Linear Model in combination with the equivolume principle of cortical layers to unmix laminar signals instead of interpolating through and integrating over a cortical area: thus reducing partial volume effects. Not only do we provide a mathematical framework for extracting laminar signals with a spatial GLM, we also illustrate that the best case scenarios of existing methods can be seen as special cases within the same framework. By means of simulation, we show that this approach has a sharper point spread function, providing better signal localisation. We further assess the partial volume contamination in cortical profiles from high resolution human ex vivo and in vivo structural data, and provide a full account of the benefits and potential caveats. We eschew here any attempt to validate the spatial GLM on the basis of fMRI data as a generally accepted ground-truth pattern of laminar activation does not currently exist. This approach is flexible in terms of the number of layers and their respective thickness, and naturally integrates spatial regularisation along the cortex, while preserving laminar specificity. Care must be taken, however, as this procedure of unmixing is susceptible to sources of noise in the data or inaccuracies in the laminar segmentation.
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Affiliation(s)
- Tim van Mourik
- Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
- * E-mail:
| | - Jan P. J. M. van der Eerden
- Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Pierre-Louis Bazin
- Integrative Model-based Cognitive Neuroscience research unit, Universiteit van Amsterdam, Amsterdam, the Netherlands
- Max Planck institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - David G. Norris
- Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany
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77
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Cinciute S. Translating the hemodynamic response: why focused interdisciplinary integration should matter for the future of functional neuroimaging. PeerJ 2019; 7:e6621. [PMID: 30941269 PMCID: PMC6438158 DOI: 10.7717/peerj.6621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 02/14/2019] [Indexed: 01/28/2023] Open
Abstract
The amount of information acquired with functional neuroimaging techniques, particularly fNIRS and fMRI, is rapidly growing and has enormous potential for studying human brain functioning. Therefore, many scientists focus on solving computational neuroimaging and Big Data issues to advance the discipline. However, the main obstacle—the accurate translation of the hemodynamic response (HR) by the investigation of a physiological phenomenon called neurovascular coupling—is still not fully overcome and, more importantly, often overlooked in this context. This article provides a brief and critical overview of significant findings from cellular biology and in vivo brain physiology with a focus on advancing existing HR modelling paradigms. A brief historical timeline of these disciplines of neuroscience is presented for readers to grasp the concept better, and some possible solutions for further scientific discussion are provided.
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Affiliation(s)
- Sigita Cinciute
- Institute of Biosciences, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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78
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Mesoscopic and microscopic imaging of sensory responses in the same animal. Nat Commun 2019; 10:1110. [PMID: 30846689 PMCID: PMC6405955 DOI: 10.1038/s41467-019-09082-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 02/20/2019] [Indexed: 01/09/2023] Open
Abstract
Imaging based on blood flow dynamics is widely used to study sensory processing. Here we investigated the extent to which local neuronal and capillary responses (two-photon microscopy) are correlated to mesoscopic responses detected with fast ultrasound (fUS) and BOLD-fMRI. Using a specialized chronic olfactory bulb preparation, we report that sequential imaging of the same mouse allows quantitative comparison of odour responses, imaged at both microscopic and mesoscopic scales. Under these conditions, functional hyperaemia occurred at the threshold of neuronal activation and fUS-CBV signals could be detected at the level of single voxels with activation maps varying according to blood velocity. Both neuronal and vascular responses increase non-linearly as a function of odour concentration, whereas both microscopic and mesoscopic vascular responses are linearly correlated to local neuronal calcium. These data establish strengths and limits of mesoscopic imaging techniques to report neural activity. Neuronal activity leads to a local increase in blood flow and volume, a process termed hyperaemia. Here, the authors employ multiple imaging approaches of neuronal and vascular activity at varying resolution to delineate the spatiotemporal dynamics of neurovascular coupling evoked by odours in the olfactory bulb.
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79
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Spatial contribution of hippocampal BOLD activation in high-resolution fMRI. Sci Rep 2019; 9:3152. [PMID: 30816226 PMCID: PMC6395694 DOI: 10.1038/s41598-019-39614-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 01/29/2019] [Indexed: 12/14/2022] Open
Abstract
While the vascular origin of the BOLD-fMRI signal is established, the exact neurovascular coupling events contributing to this signal are still incompletely understood. Furthermore, the hippocampal spatial properties of the BOLD activation are not elucidated, although electrophysiology approaches have already revealed the precise spatial patterns of neural activity. High magnetic field fMRI offers improved contrast and allows for a better correlation with the underlying neuronal activity because of the increased contribution to the BOLD signal of small blood vessels. Here, we take advantage of these two benefits to investigate the spatial characteristics of the hippocampal activation in a rat model before and after changing the hippocampal plasticity by long-term potentiation (LTP). We found that the hippocampal BOLD signals evoked by electrical stimulation at the perforant pathway increased more at the radiatum layer of the hippocampal CA1 region than at the pyramidal cell layer. The return to the baseline of the hippocampal BOLD activation was prolonged after LTP induction compared with that before most likely due vascular or neurovascular coupling changes. Based on these results, we conclude that high resolution BOLD-fMRI allows the segregation of hippocampal subfields probably based on their underlying vascular or neurovascular coupling features.
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80
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Kay K, Jamison KW, Vizioli L, Zhang R, Margalit E, Ugurbil K. A critical assessment of data quality and venous effects in sub-millimeter fMRI. Neuroimage 2019; 189:847-869. [PMID: 30731246 DOI: 10.1016/j.neuroimage.2019.02.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 02/02/2019] [Accepted: 02/04/2019] [Indexed: 01/07/2023] Open
Abstract
Advances in hardware, pulse sequences, and reconstruction techniques have made it possible to perform functional magnetic resonance imaging (fMRI) at sub-millimeter resolution while maintaining high spatial coverage and acceptable signal-to-noise ratio. Here, we examine whether sub-millimeter fMRI can be used as a routine method for obtaining accurate measurements of fine-scale local neural activity. We conducted fMRI in human visual cortex during a simple event-related visual experiment (7 T, gradient-echo EPI, 0.8-mm isotropic voxels, 2.2-s sampling rate, 84 slices), and developed analysis and visualization tools to assess the quality of the data. Our results fall along three lines of inquiry. First, we find that the acquired fMRI images, combined with appropriate surface-based processing, provide reliable and accurate measurements of fine-scale blood oxygenation level dependent (BOLD) activity patterns. Second, we show that the highly folded structure of cortex causes substantial biases on spatial resolution and data visualization. Third, we examine the well-recognized issue of venous contributions to fMRI signals. In a systematic assessment of large sections of cortex measured at a fine scale, we show that time-averaged T2*-weighted EPI intensity is a simple, robust marker of venous effects. These venous effects are unevenly distributed across cortex, are more pronounced in gyri and outer cortical depths, and are, to a certain degree, in consistent locations across subjects relative to cortical folding. Furthermore, we show that these venous effects are strongly correlated with BOLD responses evoked by the experiment. We conclude that sub-millimeter fMRI can provide robust information about fine-scale BOLD activity patterns, but special care must be exercised in visualizing and interpreting these patterns, especially with regards to the confounding influence of the brain's vasculature. To help translate these methodological findings to neuroscience research, we provide practical suggestions for both high-resolution and standard-resolution fMRI studies.
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Affiliation(s)
- Kendrick Kay
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, USA.
| | - Keith W Jamison
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, USA
| | - Luca Vizioli
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, USA
| | - Ruyuan Zhang
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, USA
| | - Eshed Margalit
- Stanford Neurosciences Institute, Stanford University, USA
| | - Kamil Ugurbil
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, USA
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81
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Senarathna J, Yu H, Deng C, Zou AL, Issa JB, Hadjiabadi DH, Gil S, Wang Q, Tyler BM, Thakor NV, Pathak AP. A miniature multi-contrast microscope for functional imaging in freely behaving animals. Nat Commun 2019; 10:99. [PMID: 30626878 PMCID: PMC6327063 DOI: 10.1038/s41467-018-07926-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 12/03/2018] [Indexed: 12/27/2022] Open
Abstract
Neurovascular coupling, cerebrovascular remodeling and hemodynamic changes are critical to brain function, and dysregulated in neuropathologies such as brain tumors. Interrogating these phenomena in freely behaving animals requires a portable microscope with multiple optical contrast mechanisms. Therefore, we developed a miniaturized microscope with: a fluorescence (FL) channel for imaging neural activity (e.g., GCaMP) or fluorescent cancer cells (e.g., 9L-GFP); an intrinsic optical signal (IOS) channel for imaging hemoglobin absorption (i.e., cerebral blood volume); and a laser speckle contrast (LSC) channel for imaging perfusion (i.e., cerebral blood flow). Following extensive validation, we demonstrate the microscope’s capabilities via experiments in unanesthetized murine brains that include: (i) multi-contrast imaging of neurovascular changes following auditory stimulation; (ii) wide-area tonotopic mapping; (iii) EEG-synchronized imaging during anesthesia recovery; and (iv) microvascular connectivity mapping over the life-cycle of a brain tumor. This affordable, flexible, plug-and-play microscope heralds a new era in functional imaging of freely behaving animals. Measuring multiple neurophysiologic variables usually requires bulky benchtop optical systems and working with anesthetized animals. Here the authors present a miniature portable microscope for neurovascular imaging in awake rodents, combining fluorescence, intrinsic optical signals and laser speckle contrast.
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Affiliation(s)
- Janaka Senarathna
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Hang Yu
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Callie Deng
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Alice L Zou
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - John B Issa
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Darian H Hadjiabadi
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Stacy Gil
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Qihong Wang
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Betty M Tyler
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Nitish V Thakor
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Arvind P Pathak
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. .,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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82
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Masamoto K, Vazquez A. Optical imaging and modulation of neurovascular responses. J Cereb Blood Flow Metab 2018; 38:2057-2072. [PMID: 30334644 PMCID: PMC6282226 DOI: 10.1177/0271678x18803372] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 09/02/2018] [Indexed: 12/17/2022]
Abstract
The cerebral microvasculature consists of pial vascular networks, parenchymal descending arterioles, ascending venules and parenchymal capillaries. This vascular compartmentalization is vital to precisely deliver blood to balance continuously varying neural demands in multiple brain regions. Optical imaging techniques have facilitated the investigation of dynamic spatial and temporal properties of microvascular functions in real time. Their combination with transgenic animal models encoding specific genetic targets have further strengthened the importance of optical methods for neurovascular research by allowing for the modulation and monitoring of neuro vascular function. Image analysis methods with three-dimensional reconstruction are also helping to understand the complexity of microscopic observations. Here, we review the compartmentalized cerebral microvascular responses to global perturbations as well as regional changes in response to neural activity to highlight the differences in vascular action sites. In addition, microvascular responses elicited by optical modulation of different cell-type targets are summarized with emphasis on variable spatiotemporal dynamics of microvascular responses. Finally, long-term changes in microvascular compartmentalization are discussed to help understand potential relationships between CBF disturbances and the development of neurodegenerative diseases and cognitive decline.
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Affiliation(s)
- Kazuto Masamoto
- Faculty of Informatics and Engineering, University of Electro-Communications, Tokyo, Japan
- Brain Science Inspired Life Support Research Center, University of Electro-Communications, Tokyo, Japan
| | - Alberto Vazquez
- Departments of Radiology and Bioengineering, University of Pittsburgh, PA, USA
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83
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Patterns of Cortical Visual Field Defects From Embolic Stroke Explained by the Anastomotic Organization of Vascular Microlobules. J Neuroophthalmol 2018; 38:538-550. [PMID: 30418333 DOI: 10.1097/wno.0000000000000733] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The cerebral cortex is supplied by vascular microlobules, each comprised of a half dozen penetrating arterioles that surround a central draining venule. The surface arterioles that feed the penetrating arterioles are interconnected via an extensively anastomotic plexus. Embolic occlusion of a small surface arteriole rarely produces a local infarct, because collateral blood flow is available through the vascular reticulum. Collateral flow also protects against infarct after occlusion of a single penetrating arteriole. Cortical infarction requires blockage of a major arterial trunk, with arrest of blood flow to a relatively large vascular territory. For striate cortex, the major vessels compromised by emboli are the inferior calcarine and superior calcarine arteries, as well as the distal branches of the middle cerebral artery. Their vascular territories have a fairly consistent relationship with the retinotopic map. Consequently, occlusion by emboli results in stereotypical visual field defects. The organization of the arterial supply to the occipital lobe provides an anatomical explanation for a phenomenon that has long puzzled neuro-ophthalmologists, namely, that of the myriad potential patterns of cortical visual field loss, only a few are encountered commonly from embolic cortical stroke.
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84
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Almairac F, Fontaine D, Demarcy T, Delingette H, Beuil S, Raffaelli C. Motor cortex neurovascular coupling: inputs from ultra-high-frequency ultrasound imaging in humans. J Neurosurg 2018; 131:1632-1638. [PMID: 30497179 DOI: 10.3171/2018.5.jns18754] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/31/2018] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Neurovascular coupling reflects the link between neural activity and changes in cerebral blood flow. Despite many technical advances in functional exploration of the brain, including functional MRI, there are only a few reports of direct evidence of neurovascular coupling in humans. The authors aimed to explore, for the first time in humans, the local cerebral blood flow of the primary motor cortex using ultra-high-frequency ultrasound (UHF-US) Doppler imaging to detect low blood flow velocity (1 mm/sec). METHODS Four consecutive patients underwent awake craniotomy for glioma resection using cortical direct electrostimulation for brain mapping. The primary motor cortical area eliciting flexion of the contralateral forearm was identified. UHF-US color Doppler imaging of this cortical area was acquired at rest, during repeated spontaneous forearm flexion, and immediately after the movement's termination. In each condition, the surface areas of the detectable vessels were measured after extraction of non-zero-velocity colored pixels and summed. RESULTS During movement, local cerebral blood flow increased significantly by 14.4% (range 5%-30%) compared with baseline. Immediately after the termination of movements, the local hyperemia decreased significantly by 8.6% (range 1.9%-15.7%). CONCLUSIONS To the authors' knowledge, this study is the first to provide a real-time demonstration of the neurovascular coupling in the human cortex by ultrasound imaging. They assume that UHF-US may be used to gather original and advanced data on brain functioning, which could be used to help in the identification of functional cortical areas during brain surgery.Clinical trial registration no.: NCT03179176 (clinicaltrials.gov).
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Affiliation(s)
| | - Denys Fontaine
- Departments of1Neurosurgery and
- 2FHU INOVPAIN, CHU de Nice, Université Cote d'Azur, Nice; and
| | - Thomas Demarcy
- 3Asclepios Research Team, INRIA Sophia Antipolis-Mediterranée, France
| | - Hervé Delingette
- 3Asclepios Research Team, INRIA Sophia Antipolis-Mediterranée, France
| | - Stéphanie Beuil
- 4Ultra-Sound Imaging, CHU de Nice, Université Cote d'Azur, Nice
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85
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Arbuckle SA, Yokoi A, Pruszynski JA, Diedrichsen J. Stability of representational geometry across a wide range of fMRI activity levels. Neuroimage 2018; 186:155-163. [PMID: 30395930 DOI: 10.1016/j.neuroimage.2018.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 10/30/2018] [Accepted: 11/01/2018] [Indexed: 02/04/2023] Open
Abstract
Fine-grained activity patterns, as measured with functional magnetic resonance imaging (fMRI), are thought to reflect underlying neural representations. Multivariate analysis techniques, such as representational similarity analysis (RSA), can be used to test models of brain representation by quantifying the representational geometry (the collection of pair-wise dissimilarities between activity patterns). One important caveat, however, is that non-linearities in the coupling between neural activity and the fMRI signal may lead to significant distortions in the representational geometry estimated from fMRI activity patterns. Here we tested the stability of representational dissimilarity measures in primary sensory-motor (S1 and M1) and early visual regions (V1/V2) across a large range of activation levels. Participants were visually cued with different letters to perform single finger presses with one of the 5 fingers at a rate of 0.3-2.6 Hz. For each stimulation frequency, we quantified the difference between the 5 activity patterns in M1, S1, and V1/V2. We found that the representational geometry remained relatively stable, even though the average activity increased over a large dynamic range. These results indicate that the representational geometry of fMRI activity patterns can be reliably assessed, largely independent of the average activity in the region. This has important methodological implications for RSA and other multivariate analysis approaches that use the representational geometry to make inferences about brain representations.
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Affiliation(s)
| | - Atsushi Yokoi
- Graduate School of Frontier Biosciences, Osaka University, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, Osaka, Japan
| | - J Andrew Pruszynski
- Brain and Mind Institute, Western University, Canada; Department of Physiology and Pharmacology, Western University, Canada; Department of Psychology, Western University, Canada; Robarts Research Institute, Western University, Canada
| | - Jörn Diedrichsen
- Brain and Mind Institute, Western University, Canada; Department of Statistical and Actuarial Sciences, Western University, Canada; Department of Computer Science, Western University, Canada.
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86
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Stability, affinity, and chromatic variants of the glutamate sensor iGluSnFR. Nat Methods 2018; 15:936-939. [PMID: 30377363 PMCID: PMC6394230 DOI: 10.1038/s41592-018-0171-3] [Citation(s) in RCA: 238] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 08/15/2018] [Indexed: 01/18/2023]
Abstract
Single-wavelength fluorescent reporters allow visualization of specific neurotransmitters with high spatial and temporal resolution. We report variants of the glutamate sensor iGluSnFR that are functionally brighter, detect sub-micromolar to millimolar glutamate, and have blue, cyan, green, or yellow emission profiles. These variants allow in vivo imaging where original iGluSnFR was too dim, can resolve glutamate transients in dendritic spines and axonal boutons, and permit kilohertz imaging.
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87
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Atry F, Chen RCH, Pisaniello J, Brodnick S, Suminski AJ, Novello J, Ness J, Williams JC, Pashaie R. Optogenetic interrogation of neurovascular coupling in the cerebral cortex of transgenic mice. J Neural Eng 2018; 15:056033. [DOI: 10.1088/1741-2552/aad840] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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88
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Hierro-Bujalance C, Bacskai BJ, Garcia-Alloza M. In Vivo Imaging of Microglia With Multiphoton Microscopy. Front Aging Neurosci 2018; 10:218. [PMID: 30072888 PMCID: PMC6060250 DOI: 10.3389/fnagi.2018.00218] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 06/26/2018] [Indexed: 01/04/2023] Open
Abstract
Neuroimaging has become an unparalleled tool to understand the central nervous system (CNS) anatomy, physiology and neurological diseases. While an altered immune function and microglia hyperactivation are common neuropathological features for many CNS disorders and neurodegenerative diseases, direct assessment of the role of microglial cells remains a challenging task. Non-invasive neuroimaging techniques, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single positron emission computed tomography (SPECT) are widely used for human clinical applications, and a variety of ligands are available to detect neuroinflammation. In animal models, intravital imaging has been largely used, and minimally invasive multiphoton microcopy (MPM) provides high resolution detection of single microglia cells, longitudinally, in living brain. In this study, we review in vivo real-time MPM approaches to assess microglia in preclinical studies, including individual cell responses in surveillance, support, protection and restoration of brain tissue integrity, synapse formation, homeostasis, as well as in different pathological situations. We focus on in vivo studies that assess the role of microglia in mouse models of Alzheimer’s disease (AD), analyzing microglial motility and recruitment, as well as the role of microglia in anti-amyloid-β treatment, as a key therapeutic approach to treat AD. Altogether, MPM provides a high contrast and high spatial resolution approach to follow microglia chronically in vivo in complex models, supporting MPM as a powerful tool for deep intravital tissue imaging.
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Affiliation(s)
- Carmen Hierro-Bujalance
- Division of Physiology, School of Medicine, Instituto de Investigación e Innovación en Ciencias Biomedicas de la Provincia de Cadiz (INiBICA), Universidad de Cádiz, Cádiz, Spain
| | - Brian J Bacskai
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Harvard University, Boston, MA, United States
| | - Monica Garcia-Alloza
- Division of Physiology, School of Medicine, Instituto de Investigación e Innovación en Ciencias Biomedicas de la Provincia de Cadiz (INiBICA), Universidad de Cádiz, Cádiz, Spain
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89
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The pial vasculature of the mouse develops according to a sensory-independent program. Sci Rep 2018; 8:9860. [PMID: 29959346 PMCID: PMC6026131 DOI: 10.1038/s41598-018-27910-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 06/12/2018] [Indexed: 12/15/2022] Open
Abstract
The cerebral vasculature is organized to supply the brain’s metabolic needs. Sensory deprivation during the early postnatal period causes altered neural activity and lower metabolic demand. Neural activity is instructional for some aspects of vascular development, and deprivation causes changes in capillary density in the deprived brain region. However, it is not known if the pial arteriole network, which contains many leptomeningeal anastomoses (LMAs) that endow the network with redundancy against occlusions, is also affected by sensory deprivation. We quantified the effects of early-life sensory deprivation via whisker plucking on the densities of LMAs and penetrating arterioles (PAs) in anatomically-identified primary sensory regions (vibrissae cortex, forelimb/hindlimb cortex, visual cortex and auditory cortex) in mice. We found that the densities of penetrating arterioles were the same across cortical regions, though the hindlimb representation had a higher density of LMAs than other sensory regions. We found that the densities of PAs and LMAs, as well as quantitative measures of network topology, were not affected by sensory deprivation. Our results show that the postnatal development of the pial arterial network is robust to sensory deprivation.
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90
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Bimbard C, Demene C, Girard C, Radtke-Schuller S, Shamma S, Tanter M, Boubenec Y. Multi-scale mapping along the auditory hierarchy using high-resolution functional UltraSound in the awake ferret. eLife 2018; 7:35028. [PMID: 29952750 PMCID: PMC6039176 DOI: 10.7554/elife.35028] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 06/16/2018] [Indexed: 12/22/2022] Open
Abstract
A major challenge in neuroscience is to longitudinally monitor whole brain activity across multiple spatial scales in the same animal. Functional UltraSound (fUS) is an emerging technology that offers images of cerebral blood volume over large brain portions. Here we show for the first time its capability to resolve the functional organization of sensory systems at multiple scales in awake animals, both within small structures by precisely mapping and differentiating sensory responses, and between structures by elucidating the connectivity scheme of top-down projections. We demonstrate that fUS provides stable (over days), yet rapid, highly-resolved 3D tonotopic maps in the auditory pathway of awake ferrets, thus revealing its unprecedented functional resolution (100/300µm). This was performed in four different brain regions, including very small (1–2 mm3 size), deeply situated subcortical (8 mm deep) and previously undescribed structures in the ferret. Furthermore, we used fUS to map long-distance projections from frontal cortex, a key source of sensory response modulation, to auditory cortex.
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Affiliation(s)
- Célian Bimbard
- Audition Team, Laboratoire des Systèmes Perceptifs CNRS UMR 8248, École Normale Supérieure, PSL Research University, Paris, France
| | - Charlie Demene
- Institut Langevin, ESPCI ParisTech, INSERM U979, CNRS UMR 7587, PSL Research University, Paris, France
| | - Constantin Girard
- Audition Team, Laboratoire des Systèmes Perceptifs CNRS UMR 8248, École Normale Supérieure, PSL Research University, Paris, France
| | - Susanne Radtke-Schuller
- Audition Team, Laboratoire des Systèmes Perceptifs CNRS UMR 8248, École Normale Supérieure, PSL Research University, Paris, France
| | - Shihab Shamma
- Audition Team, Laboratoire des Systèmes Perceptifs CNRS UMR 8248, École Normale Supérieure, PSL Research University, Paris, France.,Institute for Systems Research, Department of Electrical and Computer Engineering, University of Maryland College Park, Maryland, United States
| | - Mickael Tanter
- Institut Langevin, ESPCI ParisTech, INSERM U979, CNRS UMR 7587, PSL Research University, Paris, France
| | - Yves Boubenec
- Audition Team, Laboratoire des Systèmes Perceptifs CNRS UMR 8248, École Normale Supérieure, PSL Research University, Paris, France
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91
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Rungta RL, Chaigneau E, Osmanski BF, Charpak S. Vascular Compartmentalization of Functional Hyperemia from the Synapse to the Pia. Neuron 2018; 99:362-375.e4. [PMID: 29937277 PMCID: PMC6069674 DOI: 10.1016/j.neuron.2018.06.012] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 03/29/2018] [Accepted: 06/07/2018] [Indexed: 12/22/2022]
Abstract
Functional hyperemia, a regional increase of blood flow triggered by local neural activation, is used to map brain activity in health and disease. However, the spatial-temporal dynamics of functional hyperemia remain unclear. Two-photon imaging of the entire vascular arbor in NG2-creERT2;GCaMP6f mice shows that local synaptic activation, measured via oligodendrocyte precursor cell (OPC) Ca2+ signaling, generates a synchronous Ca2+ drop in pericytes and smooth muscle cells (SMCs) enwrapping all upstream vessels feeding the activated synapses. Surprisingly, the onset timing, direction, and amplitude of vessel diameter and blood velocity changes vary dramatically from juxta-synaptic capillaries back to the pial arteriole. These results establish a precise spatial-temporal sequence of vascular changes triggered by neural activity and essential for the interpretation of blood-flow-based imaging techniques such as BOLD-fMRI. Odor triggers rapid Ca2+ elevations in OPC process that are input specific All pericyte subtypes and SMCs respond to downstream synaptic activation Synchronous mural cell activation is associated with heterogeneous local hemodynamics The arteriole and first-order capillary dilate first and form the primary functional unit
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Affiliation(s)
- Ravi L Rungta
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris 75006, France.
| | - Emmanuelle Chaigneau
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris 75006, France
| | - Bruno-Félix Osmanski
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris 75006, France
| | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris 75006, France.
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92
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Guerra G, Lucariello A, Perna A, Botta L, De Luca A, Moccia F. The Role of Endothelial Ca 2+ Signaling in Neurovascular Coupling: A View from the Lumen. Int J Mol Sci 2018; 19:E938. [PMID: 29561829 PMCID: PMC5979341 DOI: 10.3390/ijms19040938] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 03/16/2018] [Accepted: 03/17/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Neurovascular coupling (NVC) is the mechanism whereby an increase in neuronal activity (NA) leads to local elevation in cerebral blood flow (CBF) to match the metabolic requirements of firing neurons. Following synaptic activity, an increase in neuronal and/or astrocyte Ca2+ concentration leads to the synthesis of multiple vasoactive messengers. Curiously, the role of endothelial Ca2+ signaling in NVC has been rather neglected, although endothelial cells are known to control the vascular tone in a Ca2+-dependent manner throughout peripheral vasculature. METHODS We analyzed the literature in search of the most recent updates on the potential role of endothelial Ca2+ signaling in NVC. RESULTS We found that several neurotransmitters (i.e., glutamate and acetylcholine) and neuromodulators (e.g., ATP) can induce dilation of cerebral vessels by inducing an increase in endothelial Ca2+ concentration. This, in turn, results in nitric oxide or prostaglandin E2 release or activate intermediate and small-conductance Ca2+-activated K⁺ channels, which are responsible for endothelial-dependent hyperpolarization (EDH). In addition, brain endothelial cells express multiple transient receptor potential (TRP) channels (i.e., TRPC3, TRPV3, TRPV4, TRPA1), which induce vasodilation by activating EDH. CONCLUSIONS It is possible to conclude that endothelial Ca2+ signaling is an emerging pathway in the control of NVC.
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Affiliation(s)
- Germano Guerra
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Angela Lucariello
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Angelica Perna
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Laura Botta
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
| | - Antonio De Luca
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
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93
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Bizeau A, Gilbert G, Bernier M, Huynh MT, Bocti C, Descoteaux M, Whittingstall K. Stimulus-evoked changes in cerebral vessel diameter: A study in healthy humans. J Cereb Blood Flow Metab 2018; 38:528-539. [PMID: 28361587 PMCID: PMC5851143 DOI: 10.1177/0271678x17701948] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The high metabolic demand of neuronal tissue, coupled with its relatively low energy storage capacity, requires that increases in neuronal activation are quickly matched with increased blood flow to ensure efficient supply of oxygen and nutrients to the tissue. For this to occur, dilation of nearby arterioles must be coordinated with the dilation of larger upstream feeding arteries. As it stands, the exact spatial extent of such dilation in humans is unknown. Using non-invasive time-of-flight magnetic resonance angiography in healthy participants, we developed an automatic methodology for reconstructing cerebral arterial vessels and quantifying their diameter on a voxel-by-voxel basis. Specifically, we isolated the posterior cerebral artery (PCA) supplying each occipital lobe and quantified its vasodilation induced by visual stimulation. Stimulus-induced changes were strongest (∼30%) near primary visual cortex and progressively decreased in a non-linear fashion as a function of distance. Surprisingly, weak - albeit significant - changes (∼2%) were observed ∼70 mm from the visual cortex. This demonstrates that visual stimulation modulates vascular tone along the bulk of the PCA segment, and thus may have important implications for our understanding of functional hyperemia in healthy and diseased states.
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Affiliation(s)
- Alexandre Bizeau
- 1 Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada.,2 Molecular Imagery Center of Sherbrooke (CIMS), Clinical Research Center (CRC) of Sherbrooke University Hospital Center (CHUS), Sherbrooke, QC, Canada
| | | | - Michaël Bernier
- 1 Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada.,2 Molecular Imagery Center of Sherbrooke (CIMS), Clinical Research Center (CRC) of Sherbrooke University Hospital Center (CHUS), Sherbrooke, QC, Canada
| | - Minh Tung Huynh
- 4 Department of Diagnostic Radiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Christian Bocti
- 5 Division of Neurology, Department of Medicine, and Research Center on Aging, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Maxime Descoteaux
- 2 Molecular Imagery Center of Sherbrooke (CIMS), Clinical Research Center (CRC) of Sherbrooke University Hospital Center (CHUS), Sherbrooke, QC, Canada.,6 Department of Computer Science, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Kevin Whittingstall
- 1 Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada.,2 Molecular Imagery Center of Sherbrooke (CIMS), Clinical Research Center (CRC) of Sherbrooke University Hospital Center (CHUS), Sherbrooke, QC, Canada.,4 Department of Diagnostic Radiology, Université de Sherbrooke, Sherbrooke, QC, Canada
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94
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Linking brain vascular physiology to hemodynamic response in ultra-high field MRI. Neuroimage 2018; 168:279-295. [DOI: 10.1016/j.neuroimage.2017.02.063] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 01/05/2023] Open
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95
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Poser BA, Setsompop K. Pulse sequences and parallel imaging for high spatiotemporal resolution MRI at ultra-high field. Neuroimage 2018; 168:101-118. [PMID: 28392492 PMCID: PMC5630499 DOI: 10.1016/j.neuroimage.2017.04.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/01/2017] [Accepted: 04/03/2017] [Indexed: 12/18/2022] Open
Abstract
The SNR and CNR benefits of ultra-high field (UHF) have helped push the envelope of achievable spatial resolution in MRI. For applications based on susceptibility contrast where there is a large CNR gain, high quality sub-millimeter resolution imaging is now being routinely performed, particularly in fMRI and phase imaging/QSM. This has enabled the study of structure and function of very fine-scale structures in the brain. UHF has also helped push the spatial resolution of many other MRI applications as will be outlined in this review. However, this push in resolution comes at a cost of a large encoding burden leading to very lengthy scans. Developments in parallel imaging with controlled aliasing and the move away from 2D slice-by-slice imaging to much more SNR-efficient simultaneous multi-slice (SMS) and 3D acquisitions have helped address this issue. In particular, these developments have revolutionized the efficiency of UHF MRI to enable high spatiotemporal resolution imaging at an order of magnitude faster acquisition. In addition to describing the main approaches to these techniques, this review will also outline important key practical considerations in using these methods in practice. Furthermore, new RF pulse design to tackle the B1+ and SAR issues of UHF and the increased SAR and power requirement of SMS RF pulses will also be touched upon. Finally, an outlook into new developments of smart encoding in more dimensions, particularly through using better temporal/across-contrast encoding and reconstruction will be described. Just as controlled aliasing fully exploits spatial encoding in parallel imaging to provide large multiplicative gains in accelerations, the complimentary use of these new approaches in temporal and across-contrast encoding are expected to provide exciting opportunities for further large gains in efficiency to further push the spatiotemporal resolution of MRI.
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Affiliation(s)
- Benedikt A Poser
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands.
| | - Kawin Setsompop
- Department of Radiology, Harvard Medical School, Boston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
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96
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How to choose the right MR sequence for your research question at 7 T and above? Neuroimage 2018; 168:119-140. [DOI: 10.1016/j.neuroimage.2017.04.044] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 12/29/2022] Open
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97
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Uğurbil K. Imaging at ultrahigh magnetic fields: History, challenges, and solutions. Neuroimage 2018; 168:7-32. [PMID: 28698108 PMCID: PMC5758441 DOI: 10.1016/j.neuroimage.2017.07.007] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 07/05/2017] [Accepted: 07/07/2017] [Indexed: 01/06/2023] Open
Abstract
Following early efforts in applying nuclear magnetic resonance (NMR) spectroscopy to study biological processes in intact systems, and particularly since the introduction of 4 T human scanners circa 1990, rapid progress was made in imaging and spectroscopy studies of humans at 4 T and animal models at 9.4 T, leading to the introduction of 7 T and higher magnetic fields for human investigation at about the turn of the century. Work conducted on these platforms has provided numerous technological solutions to challenges posed at these ultrahigh fields, and demonstrated the existence of significant advantages in signal-to-noise ratio and biological information content. Primary difference from lower fields is the deviation from the near field regime at the radiofrequencies (RF) corresponding to hydrogen resonance conditions. At such ultrahigh fields, the RF is characterized by attenuated traveling waves in the human body, which leads to image non-uniformities for a given sample-coil configuration because of destructive and constructive interferences. These non-uniformities were initially considered detrimental to progress of imaging at high field strengths. However, they are advantageous for parallel imaging in signal reception and transmission, two critical technologies that account, to a large extend, for the success of ultrahigh fields. With these technologies and improvements in instrumentation and imaging methods, today ultrahigh fields have provided unprecedented gains in imaging of brain function and anatomy, and started to make inroads into investigation of the human torso and extremities. As extensive as they are, these gains still constitute a prelude to what is to come given the increasingly larger effort committed to ultrahigh field research and development of ever better instrumentation and techniques.
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Affiliation(s)
- Kamil Uğurbil
- Center for Magnetic Resonance Research (CMRR), University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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98
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Kirschen GW, Kéry R, Liu H, Ahamad A, Chen L, Akmentin W, Kumar R, Levine J, Xiong Q, Ge S. Genetic dissection of the neuro-glio-vascular machinery in the adult brain. Mol Brain 2018; 11:2. [PMID: 29335006 PMCID: PMC5769320 DOI: 10.1186/s13041-017-0345-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 12/21/2017] [Indexed: 12/30/2022] Open
Abstract
The adult brain actively controls its metabolic homeostasis via the circulatory system at the blood brain barrier interface. The mechanisms underlying the functional coupling from neuron to vessel remain poorly understood. Here, we established a novel method to genetically isolate the individual components of this coupling machinery using a combination of viral vectors. We first discovered a surprising non-uniformity of the glio-vascular structure in different brain regions. We carried out a viral injection screen and found that intravenous Canine Adenovirus 2 (CAV2) preferentially targeted perivascular astrocytes throughout the adult brain, with sparing of the hippocampal hilus from infection. Using this new intravenous method to target astrocytes, we selectively ablated these cells and observed severe defects in hippocampus-dependent contextual memory and the metabolically regulated process of hippocampal neurogenesis. Combined with AAV9 targeting of neurons and endothelial cells, all components of the neuro-glio-vascular machinery can be simultaneously labeled for genetic manipulation. Together, we demonstrate a novel method, which we term CATNAP (CAV/AAV Targeting of Neurons and Astrocytes Perivascularly), to target and manipulate the neuro-glio-vascular machinery in the adult brain.
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Affiliation(s)
- Gregory W Kirschen
- Medical Scientist Training Program, Stony Brook, New York, USA.,Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA
| | - Rachel Kéry
- Medical Scientist Training Program, Stony Brook, New York, USA.,Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA
| | - Hanxiao Liu
- Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA
| | - Afrinash Ahamad
- School of Health Technology & Management, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Liang Chen
- Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA
| | - Wendy Akmentin
- Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA
| | - Ramya Kumar
- Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA
| | - Joel Levine
- Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA
| | - Qiaojie Xiong
- Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA.
| | - Shaoyu Ge
- Department of Neurobiology & Behavior, SUNY Stony Brook, Stony Brook, NY, 11794, USA.
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99
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Chen X, Lin W, Wang C, Chen S, Sheng J, Zeng B, Xu M. In vivo real-time imaging of cutaneous hemoglobin concentration, oxygen saturation, scattering properties, melanin content, and epidermal thickness with visible spatially modulated light. BIOMEDICAL OPTICS EXPRESS 2017; 8:5468-5482. [PMID: 29296481 PMCID: PMC5745096 DOI: 10.1364/boe.8.005468] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/20/2017] [Accepted: 10/24/2017] [Indexed: 05/04/2023]
Abstract
We present the real-time single snapshot multiple frequency demodulation - spatial frequency domain imaging (SSMD-SFDI) platform implemented with a visible digital mirror device that is capable of imaging and monitoring dynamic turbid medium and processes over a large field of view. One challenge in quantitative imaging of biological tissue such as the skin is the complex structure rendering techniques based on homogeneous medium models to fail. To address this difficulty we have also developed a novel method that maps the layered structure to a homogeneous medium for spatial frequency domain imaging. The varying penetration depth of spatially modulated light on its wavelength and modulation frequency is used to resolve the layered structure. The efficacy of the real-time SSMD-SFDI platform and this two-layer model is demonstrated by imaging forearms of 6 healthy subjects under the reactive hyperemia protocol. The results show that our approach not only successfully decouples light absorption by melanin from that by hemoglobin and yields accurate determination of cutaneous hemoglobin concentration and oxygen saturation, but also provides reliable estimation of the scattering properties, the melanin content and the epidermal thickness in real time. Potential applications of our system in imaging skin physiological and functional states, cancer screening, and microcirculation monitoring are discussed at the end.
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Affiliation(s)
- Xinlin Chen
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Weihao Lin
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Chenge Wang
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Shaoheng Chen
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Jing Sheng
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Bixin Zeng
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - M. Xu
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
- Dept. of Physics, Fairfield University, 1073 North Road, Fairfield, CT 06824, USA
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100
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Ugurbil K. What is feasible with imaging human brain function and connectivity using functional magnetic resonance imaging. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0361. [PMID: 27574313 DOI: 10.1098/rstb.2015.0361] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2016] [Indexed: 12/12/2022] Open
Abstract
When we consider all of the methods we employ to detect brain function, from electrophysiology to optical techniques to functional magnetic resonance imaging (fMRI), we do not really have a 'golden technique' that meets all of the needs for studying the brain. We have methods, each of which has significant limitations but provide often complimentary information. Clearly, there are many questions that need to be answered about fMRI, which unlike other methods, allows us to study the human brain. However, there are also extraordinary accomplishments or demonstration of the feasibility of reaching new and previously unexpected scales of function in the human brain. This article reviews some of the work we have pursued, often with extensive collaborations with other co-workers, towards understanding the underlying mechanisms of the methodology, defining its limitations, and developing solutions to advance it. No doubt, our knowledge of human brain function has vastly expanded since the introduction of fMRI. However, methods and instrumentation in this dynamic field have evolved to a state that discoveries about the human brain based on fMRI principles, together with information garnered at a much finer spatial and temporal scale through other methods, are poised to significantly accelerate in the next decade.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
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Affiliation(s)
- Kamil Ugurbil
- Center for Magnetic Resonance Research (CMRR), University of Minnesota Medical School, Minneapolis, MN 55455, USA
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