1
|
Barbaresi P, Fabri M, Lorenzi T, Sagrati A, Morroni M. Intrinsic organization of the corpus callosum. Front Physiol 2024; 15:1393000. [PMID: 39035452 PMCID: PMC11259024 DOI: 10.3389/fphys.2024.1393000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 05/16/2024] [Indexed: 07/23/2024] Open
Abstract
The corpus callosum-the largest commissural fiber system connecting the two cerebral hemispheres-is considered essential for bilateral sensory integration and higher cognitive functions. Most studies exploring the corpus callosum have examined either the anatomical, physiological, and neurochemical organization of callosal projections or the functional and/or behavioral aspects of the callosal connections after complete/partial callosotomy or callosal lesion. There are no works that address the intrinsic organization of the corpus callosum. We review the existing information on the activities that take place in the commissure in three sections: I) the topographical and neurochemical organization of the intracallosal fibers, II) the role of glia in the corpus callosum, and III) the role of the intracallosal neurons.
Collapse
Affiliation(s)
- Paolo Barbaresi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Mara Fabri
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Teresa Lorenzi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Andrea Sagrati
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Manrico Morroni
- Electron Microscopy Unit, Azienda Ospedaliero-Universitaria, Ancona, Italy
| |
Collapse
|
2
|
Khadka N, Bikson M. Neurocapillary-Modulation. Neuromodulation 2022; 25:1299-1311. [PMID: 33340187 PMCID: PMC8213863 DOI: 10.1111/ner.13338] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 11/05/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023]
Abstract
OBJECTIVES We consider two consequences of brain capillary ultrastructure in neuromodulation. First, blood-brain barrier (BBB) polarization as a consequence of current crossing between interstitial space and the blood. Second, interstitial current flow distortion around capillaries impacting neuronal stimulation. MATERIALS AND METHODS We developed computational models of BBB ultrastructure morphologies to first assess electric field amplification at the BBB (principle 1) and neuron polarization amplification by the presence of capillaries (principle 2). We adapt neuron cable theory to develop an analytical solution for maximum BBB polarization sensitivity. RESULTS Electrical current crosses between the brain parenchyma (interstitial space) and capillaries, producing BBB electric fields (EBBB) that are >400x of the average parenchyma electric field (ĒBRAIN), which in turn modulates transport across the BBB. Specifically, for a BBB space constant (λBBB) and wall thickness (dth-BBB), the analytical solution for maximal BBB electric field (EABBB) is given as: (ĒBRAIN × λBBB)/dth-BBB. Electrical current in the brain parenchyma is distorted around brain capillaries, amplifying neuronal polarization. Specifically, capillary ultrastructure produces ∼50% modulation of the ĒBRAIN over the ∼40 μm inter-capillary distance. The divergence of EBRAIN (Activating function) is thus ∼100 kV/m2 per unit ĒBRAIN. CONCLUSIONS BBB stimulation by principle 1 suggests novel therapeutic strategies such as boosting metabolic capacity or interstitial fluid clearance. Whereas the spatial profile of EBRAIN is traditionally assumed to depend only on macroscopic anatomy, principle 2 suggests a central role for local capillary ultrastructure-which impact forms of neuromodulation including deep brain stimulation (DBS), spinal cord stimulation (SCS), transcranial magnetic stimulation (TMS), electroconvulsive therapy (ECT), and transcranial electrical stimulation (tES)/transcranial direct current stimulation (tDCS).
Collapse
Affiliation(s)
- Niranjan Khadka
- Department of Psychiatry, Laboratory for Neuropsychiatry and Neuromodulation, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, CUNY, New York, NY, USA.
| |
Collapse
|
3
|
Skoven CS, Tomasevic L, Kvitsiani D, Pakkenberg B, Dyrby TB, Siebner HR. Dose-response relationship between the variables of unilateral optogenetic stimulation and transcallosal evoked responses in rat motor cortex. Front Neurosci 2022; 16:968839. [PMID: 36213739 PMCID: PMC9539969 DOI: 10.3389/fnins.2022.968839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 08/19/2022] [Indexed: 11/17/2022] Open
Abstract
Efficient interhemispheric integration of neural activity between left and right primary motor cortex (M1) is critical for inter-limb motor control. We employed optogenetic stimulation to establish a framework for probing transcallosal M1–M1 interactions in rats. We performed optogenetic stimulation of excitatory neurons in right M1 of male Sprague-Dawley rats. We recorded the transcallosal evoked potential in contralateral left M1 via chronically implanted electrodes. Recordings were performed under anesthesia combination of dexmedetomidine and a low concentration of isoflurane. We systematically varied the stimulation intensity and duration to characterize the relationship between stimulation parameters in right M1 and the characteristics of the evoked intracortical potentials in left M1. Optogenetic stimulation of right M1 consistently evoked a transcallosal response in left M1 with a consistent negative peak (N1) that sometimes was preceded by a smaller positive peak (P1). Higher stimulation intensity or longer stimulation duration gradually increased N1 amplitude and reduced N1 variability across trials. A combination of stimulation intensities of 5–10 mW with stimulus durations of 1–10 ms were generally sufficient to elicit a robust transcallosal response in most animal, with our optic fiber setup. Optogenetically stimulated excitatory neurons in M1 can reliably evoke a transcallosal response in anesthetized rats. Characterizing the relationship between “stimulation dose” and “response magnitude” (i.e., the gain function) of transcallosal M1-to-M1 excitatory connections can be used to optimize the variables of optogenetic stimulation and ensure stimulation efficacy.
Collapse
Affiliation(s)
- Christian Stald Skoven
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark
- Center for Functional Integrative Neuroscience, Aarhus University (AU), Aarhus, Denmark
- *Correspondence: Christian Stald Skoven,
| | - Leo Tomasevic
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark
| | - Duda Kvitsiani
- Department of Molecular Biology and Genetics, Danish Research Institute of Translational Neuroscience, Aarhus University, Aarhus, Denmark
| | - Bente Pakkenberg
- Research Laboratory for Stereology and Neuroscience, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tim Bjørn Dyrby
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Hartwig Roman Siebner
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Neurology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
- Hartwig Roman Siebner,
| |
Collapse
|
4
|
Gagliano G, Monteverdi A, Casali S, Laforenza U, Gandini Wheeler-Kingshott CAM, D’Angelo E, Mapelli L. Non-Linear Frequency Dependence of Neurovascular Coupling in the Cerebellar Cortex Implies Vasodilation-Vasoconstriction Competition. Cells 2022; 11:1047. [PMID: 35326498 PMCID: PMC8947624 DOI: 10.3390/cells11061047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/11/2022] [Accepted: 03/17/2022] [Indexed: 01/28/2023] Open
Abstract
Neurovascular coupling (NVC) is the process associating local cerebral blood flow (CBF) to neuronal activity (NA). Although NVC provides the basis for the blood oxygen level dependent (BOLD) effect used in functional MRI (fMRI), the relationship between NVC and NA is still unclear. Since recent studies reported cerebellar non-linearities in BOLD signals during motor tasks execution, we investigated the NVC/NA relationship using a range of input frequencies in acute mouse cerebellar slices of vermis and hemisphere. The capillary diameter increased in response to mossy fiber activation in the 6-300 Hz range, with a marked inflection around 50 Hz (vermis) and 100 Hz (hemisphere). The corresponding NA was recorded using high-density multi-electrode arrays and correlated to capillary dynamics through a computational model dissecting the main components of granular layer activity. Here, NVC is known to involve a balance between the NMDAR-NO pathway driving vasodilation and the mGluRs-20HETE pathway driving vasoconstriction. Simulations showed that the NMDAR-mediated component of NA was sufficient to explain the time course of the capillary dilation but not its non-linear frequency dependence, suggesting that the mGluRs-20HETE pathway plays a role at intermediate frequencies. These parallel control pathways imply a vasodilation-vasoconstriction competition hypothesis that could adapt local hemodynamics at the microscale bearing implications for fMRI signals interpretation.
Collapse
Affiliation(s)
- Giuseppe Gagliano
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (G.G.); (A.M.); (S.C.); (C.A.M.G.W.-K.)
| | - Anita Monteverdi
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (G.G.); (A.M.); (S.C.); (C.A.M.G.W.-K.)
- IRCCS Mondino Foundation, 27100 Pavia, Italy
| | - Stefano Casali
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (G.G.); (A.M.); (S.C.); (C.A.M.G.W.-K.)
| | - Umberto Laforenza
- Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy;
| | - Claudia A. M. Gandini Wheeler-Kingshott
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (G.G.); (A.M.); (S.C.); (C.A.M.G.W.-K.)
- IRCCS Mondino Foundation, 27100 Pavia, Italy
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, London WC1N3 BG, UK
| | - Egidio D’Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (G.G.); (A.M.); (S.C.); (C.A.M.G.W.-K.)
- IRCCS Mondino Foundation, 27100 Pavia, Italy
| | - Lisa Mapelli
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (G.G.); (A.M.); (S.C.); (C.A.M.G.W.-K.)
| |
Collapse
|
5
|
Chen Y, Wang Q, Choi S, Zeng H, Takahashi K, Qian C, Yu X. Focal fMRI signal enhancement with implantable inductively coupled detectors. Neuroimage 2022; 247:118793. [PMID: 34896291 PMCID: PMC8842502 DOI: 10.1016/j.neuroimage.2021.118793] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 12/02/2021] [Accepted: 12/07/2021] [Indexed: 12/16/2022] Open
Abstract
Despite extensive efforts to increase the signal-to-noise ratio (SNR) of fMRI images for brain-wide mapping, technical advances of focal brain signal enhancement are lacking, in particular, for animal brain imaging. Emerging studies have combined fMRI with fiber optic-based optogenetics to decipher circuit-specific neuromodulation from meso to macroscales. High-resolution fMRI is needed to integrate hemodynamic responses into cross-scale functional dynamics, but the SNR remains a limiting factor given the complex implantation setup of animal brains. Here, we developed a multimodal fMRI imaging platform with an implanted inductive coil detector. This detector boosts the tSNR of MRI images, showing a 2-3-fold sensitivity gain over conventional coil configuration. In contrast to the cryoprobe or array coils with limited spaces for implanted brain interface, this setup offers a unique advantage to study brain circuit connectivity with optogenetic stimulation and can be further extended to other multimodal fMRI mapping schemes.
Collapse
Affiliation(s)
- Yi Chen
- Max Planck Institute for Biological Cybernetics, 72076 Tuebingen, Germany; Max Planck Institute for the Science of Light, 91058, Erlangen, Germany
| | - Qi Wang
- Max Planck Institute for Biological Cybernetics, 72076 Tuebingen, Germany; Graduate Training Centre of Neuroscience, University of Tuebingen, 72076 Tuebingen, Germany
| | - Sangcheon Choi
- Max Planck Institute for Biological Cybernetics, 72076 Tuebingen, Germany; Graduate Training Centre of Neuroscience, University of Tuebingen, 72076 Tuebingen, Germany
| | - Hang Zeng
- Max Planck Institute for Biological Cybernetics, 72076 Tuebingen, Germany; Graduate Training Centre of Neuroscience, University of Tuebingen, 72076 Tuebingen, Germany
| | - Kengo Takahashi
- Max Planck Institute for Biological Cybernetics, 72076 Tuebingen, Germany; Graduate Training Centre of Neuroscience, University of Tuebingen, 72076 Tuebingen, Germany
| | - Chunqi Qian
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA.
| | - Xin Yu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
| |
Collapse
|
6
|
Dehghani A, Phisonkunkasem T, Yilmaz Ozcan S, Dalkara T, van den Maagdenberg AMJM, Tolner EA, Karatas H. Widespread brain parenchymal HMGB1 and NF-κB neuroinflammatory responses upon cortical spreading depolarization in familial hemiplegic migraine type 1 mice. Neurobiol Dis 2021; 156:105424. [PMID: 34118418 DOI: 10.1016/j.nbd.2021.105424] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 04/04/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
Neuroinflammatory changes involving neuronal HMGB1 release and astrocytic NF-κB nuclear translocation occur following cortical spreading depolarization (CSD) in wildtype (WT) mice but it is unknown to what extent this occurs in the migraine brain. We therefore investigated in familial hemiplegic migraine type 1 (FHM1) knock-in mice, which express an intrinsic hyperexcitability phenotype, the extent of neuroinflammation without and after CSD. CSD was evoked in one hemisphere by pinprick (single CSD) or topical KCl application (multiple CSDs). Neuroinflammatory (HMGB1, NF-κB) and neuronal activation (pERK) markers were investigated by immunohistochemistry in the brains of WT and FHM1 mutant mice without and after CSD. Effects of NMDA receptor antagonism on basal and CSD-induced neuroinflammatory changes were examined by, respectively, systemically administered MK801 and ifenprodil or topical MK801 application. In FHM1 mutant mice, CSD caused enhanced neuronal HMGB1 release and astrocytic NF-κB nuclear translocation in the cortex and subcortical areas that were equally high in both hemispheres. In WT mice such effects were only pronounced in the hemisphere in which CSD was induced. Neuroinflammatory responses were associated with pERK expression indicating neuronal activation. Upon CSD, contralateral cortical and striatal HMGB1 release was reduced by topical application of MK801 in the hemisphere contralateral to the one in which CSD was induced. This study reveals that neuroinflammatory activation after CSD is widespread and extends to the contralateral hemisphere, particularly in brains of FHM1 mutant mice. Effective blockade of CSD-induced neuroinflammatory responses in the contralateral hemisphere in FHM1 mice by local NMDA receptor antagonism suggests that neuronal hyperexcitability-related neuroinflammation is relevant in migraine pathophysiology, but possibly also other neurological disorders in which spreading depolarization is involved.
Collapse
Affiliation(s)
- Anisa Dehghani
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.
| | - Thas Phisonkunkasem
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Sinem Yilmaz Ozcan
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Arn M J M van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands; Department of Neurology, Leiden University Medical Center, Leiden, the Netherlands
| | - Else A Tolner
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands; Department of Neurology, Leiden University Medical Center, Leiden, the Netherlands
| | - Hulya Karatas
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.
| |
Collapse
|
7
|
Chen Y, Sobczak F, Pais-Roldán P, Schwarz C, Koretsky AP, Yu X. Mapping the Brain-Wide Network Effects by Optogenetic Activation of the Corpus Callosum. Cereb Cortex 2020; 30:5885-5898. [PMID: 32556241 DOI: 10.1093/cercor/bhaa164] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/25/2020] [Accepted: 05/25/2020] [Indexed: 12/18/2022] Open
Abstract
Optogenetically driven manipulation of circuit-specific activity enables causality studies, but its global brain-wide effect is rarely reported. Here, we applied simultaneous functional magnetic resonance imaging (fMRI) and calcium recording with optogenetic activation of the corpus callosum (CC) connecting barrel cortices (BC). Robust positive BOLD was detected in the ipsilateral BC due to antidromic activity, spreading to the ipsilateral motor cortex (MC), and posterior thalamus (PO). In the orthodromic target, positive BOLD was reliably evoked by 2 Hz light pulses, whereas 40 Hz light pulses led to reduced calcium, indicative of CC-mediated inhibition. This presumed optogenetic CC-mediated inhibition was further elucidated by pairing light pulses with whisker stimulation at varied interstimulus intervals. Whisker-induced positive BOLD and calcium signals were reduced at intervals of 50/100 ms. The calcium-amplitude-modulation-based correlation with whole-brain fMRI signal revealed that the inhibitory effects spread to contralateral BC, ipsilateral MC, and PO. This work raises the need for fMRI to elucidate the brain-wide network activation in response to optogenetic stimulation.
Collapse
Affiliation(s)
- Yi Chen
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Baden-Württemberg 72074, Germany
| | - Filip Sobczak
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Baden-Württemberg 72074, Germany
| | - Patricia Pais-Roldán
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Baden-Württemberg 72074, Germany
| | - Cornelius Schwarz
- Werner Reichardt Center for Integrative Neuroscience, Tübingen, Baden-Württemberg 72076, Germany
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Xin Yu
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| |
Collapse
|
8
|
Noor MS, Yu L, Murari K, Kiss ZHT. Neurovascular coupling during deep brain stimulation. Brain Stimul 2020; 13:916-927. [DOI: 10.1016/j.brs.2020.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 02/29/2020] [Accepted: 03/09/2020] [Indexed: 12/30/2022] Open
|
9
|
Zhang X, Pan WJ, Keilholz S. The Relationship Between Local Field Potentials and the Blood-Oxygenation-Level Dependent MRI Signal Can Be Non-linear. Front Neurosci 2019; 13:1126. [PMID: 31708727 PMCID: PMC6823197 DOI: 10.3389/fnins.2019.01126] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 10/04/2019] [Indexed: 01/29/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) is currently one of the most important neuroimaging methods in neuroscience. The image contrast in fMRI relies on the blood-oxygenation-level dependent (BOLD) signal, which indirectly reflects neural activity through neurovascular coupling. Because the mechanism that links the BOLD signal to neural activities involves multiple complicated processes, where neural activity, regional metabolism, hemodynamics, and the BOLD signal are all inter-connected, understanding the quantitative relationship between the BOLD signal and the underlying neural activities is crucial for interpreting fMRI data. Simultaneous local field potential (LFP) and fMRI recordings provide a method to study neurovascular coupling. There were a few studies that have shown non-linearities in stimulus related responses, but whether there is any non-linearity in LFP—BOLD relationship at rest has not been specifically quantified. In this study, we analyzed the simultaneous LFP and resting state-fMRI data acquired from rodents, and found that the relationship between LFP and BOLD is non-linear under isoflurane (ISO) anesthesia, but linear under dexmedetomidine (DMED) anesthesia. Subsequent analysis suggests that such non-linearity may come from the non-Gaussian distribution of LFP power and switching from LFP power to LFP amplitude can alleviate the problem to a degree. We also confirmed that, despite the non-linearity in the mean LFP—BOLD curve, the Pearson correlation between the two signals is relatively unaffected.
Collapse
Affiliation(s)
- Xiaodi Zhang
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA, United States
| | - Wen-Ju Pan
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA, United States
| | - Shella Keilholz
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA, United States
| |
Collapse
|
10
|
Xiao T, Wang Y, Wei H, Yu P, Jiang Y, Mao L. Electrochemical Monitoring of Propagative Fluctuation of Ascorbate in the Live Rat Brain during Spreading Depolarization. Angew Chem Int Ed Engl 2019; 58:6616-6619. [DOI: 10.1002/anie.201901035] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/20/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Tongfang Xiao
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
| | - Yuexiang Wang
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
| | - Huan Wei
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Ping Yu
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Ying Jiang
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
| | - Lanqun Mao
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| |
Collapse
|
11
|
Xiao T, Wang Y, Wei H, Yu P, Jiang Y, Mao L. Electrochemical Monitoring of Propagative Fluctuation of Ascorbate in the Live Rat Brain during Spreading Depolarization. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201901035] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Tongfang Xiao
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
| | - Yuexiang Wang
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
| | - Huan Wei
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Ping Yu
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Ying Jiang
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
| | - Lanqun Mao
- Beijing National Laboratory for Molecular SciencesKey Laboratory of Analytical Chemistry for Living BiosystemsInstitute of Chemistry, theChinese Academy of Sciences (CAS)CAS Research/Education Center for Excellence in Molecular Science Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| |
Collapse
|
12
|
Yuan Y, Wang Z, Wang X, Yan J, Liu M, Li X. Low-Intensity Pulsed Ultrasound Stimulation Induces Coupling Between Ripple Neural Activity and Hemodynamics in the Mouse Visual Cortex. Cereb Cortex 2018; 29:3220-3223. [DOI: 10.1093/cercor/bhy187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Indexed: 12/19/2022] Open
Abstract
Abstract
Several studies have separately investigated neural activities and hemodynamic responses induced by low-intensity pulsed ultrasound stimulation (LIPUS), less is known about their coupling under LIPUS. This study aims to investigate the neurovascular coupling with LIPUS by measuring neural activity and hemodynamics. We found that the relative power and sample entropy of local field potential at the ripple band have a significant correlation to relative cerebral blood flow over time (correlation coefficients: 0.66 ± 0.13 [P < 0.01] and −0.58 ± 0.11 [P < 0.05]). These results demonstrate that LIPUS can induce neurovascular coupling in the mouse visual cortex.
Collapse
Affiliation(s)
- Yi Yuan
- Institute of Electrical Engineering, Yanshan University, Qinhuangdao, China
| | - Zhijie Wang
- Institute of Electrical Engineering, Yanshan University, Qinhuangdao, China
| | - Xingran Wang
- Institute of Electrical Engineering, Yanshan University, Qinhuangdao, China
| | - Jiaqing Yan
- College of Electrical and Control Engineering, North China University of Technology, Beijing, China
| | - Mengyang Liu
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna , Austria
| | - Xiaoli Li
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| |
Collapse
|
13
|
Iordanova B, Vazquez A, Kozai TDY, Fukuda M, Kim SG. Optogenetic investigation of the variable neurovascular coupling along the interhemispheric circuits. J Cereb Blood Flow Metab 2018; 38:627-640. [PMID: 29372655 PMCID: PMC5888863 DOI: 10.1177/0271678x18755225] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 01/03/2018] [Indexed: 12/13/2022]
Abstract
The interhemispheric circuit connecting the left and the right mammalian brain plays a key role in integration of signals from the left and the right side of the body. The information transfer is carried out by modulation of simultaneous excitation and inhibition. Hemodynamic studies of this circuit are inconsistent since little is known about neurovascular coupling of mixed excitatory and inhibitory signals. We investigated the variability in hemodynamic responses driven by the interhemispheric circuit during optogenetic and somatosensory activation. We observed differences in the neurovascular response based on the stimulation site - cell bodies versus distal projections. In half of the experiments, optogenetic stimulation of the cell bodies evoked a predominant post-synaptic inhibition in the other hemisphere, accompanied by metabolic oxygen consumption without coupled functional hyperemia. When the same transcallosal stimulation resulted in predominant post-synaptic excitation, the hemodynamic response was biphasic, consisting of metabolic dip followed by functional hyperemia. Optogenetic suppression of the postsynaptic excitation abolished the coupled functional hyperemia. In contrast, light stimulation at distal projections evoked consistently a metabolic response. Our findings suggest that functional hyperemia requires signals originating from the cell body and the hemodynamic response variability appears to reflect the balance between the post-synaptic excitation and inhibition.
Collapse
Affiliation(s)
- Bistra Iordanova
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alberto Vazquez
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Takashi DY Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mitsuhiro Fukuda
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea
| |
Collapse
|
14
|
Chen G, Carter RE, Cleary JD, Reid TS, Ranum LP, Swanson MS, Ebner TJ. Altered levels of the splicing factor muscleblind modifies cerebral cortical function in mouse models of myotonic dystrophy. Neurobiol Dis 2018; 112:35-48. [PMID: 29331264 PMCID: PMC5859959 DOI: 10.1016/j.nbd.2018.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 12/20/2017] [Accepted: 01/08/2018] [Indexed: 01/18/2023] Open
Abstract
Myotonic dystrophy (DM) is a progressive, multisystem disorder affecting skeletal muscle, heart, and central nervous system. In both DM1 and DM2, microsatellite expansions of CUG and CCUG RNA repeats, respectively, accumulate and disrupt functions of alternative splicing factors, including muscleblind (MBNL) proteins. Grey matter loss and white matter changes, including the corpus callosum, likely underlie cognitive and executive function deficits in DM patients. However, little is known how cerebral cortical circuitry changes in DM. Here, flavoprotein optical imaging was used to assess local and contralateral responses to intracortical motor cortex stimulation in DM-related mouse models. In control mice, brief train stimulation generated ipsilateral and contralateral homotopic fluorescence increases, the latter mediated by the corpus callosum. Single pulse stimulation produced an excitatory response with an inhibitory-like surround response mediated by GABAA receptors. In a mouse model of DM2 (Mbnl2 KO), we observed prolonged and increased responsiveness to train stimulation and loss of the inhibition from single pulse stimulation. Conversely, mice overexpressing human MBNL1 (MBNL1-OE) exhibited decreased contralateral response to train stimulation and reduction of inhibitory-like surround to single pulse stimulation. Therefore, altering levels of two key DM-associated splicing factors modifies functions of local cortical circuits and contralateral responses mediated through the corpus callosum.
Collapse
Affiliation(s)
- Gang Chen
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Russell E Carter
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - John D Cleary
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Tammy S Reid
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Laura P Ranum
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Maurice S Swanson
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA.
| |
Collapse
|
15
|
Koo H, Kim MS, Han SW, Paulus W, Nitche MA, Kim YH, Kim HI, Ko SH, Shin YI. After-effects of anodal transcranial direct current stimulation on the excitability of the motor cortex in rats. Restor Neurol Neurosci 2018; 34:859-68. [PMID: 27567759 DOI: 10.3233/rnn-160664] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE Transcranial direct current stimulation (tDCS) is increasingly seen as a useful tool for noninvasive cortical neuromodulation. A number of studies in humans have shown that when tDCS is applied to the motor cortex it can modulate cortical excitability. It is especially interesting to note that when applied with sufficient duration and intensity, tDCS can enable long-lasting neuroplastic effects. However, the mechanism by which tDCS exerts its effects on the cortex is not fully understood. We investigated the effects of anodal tDCS under urethane anesthesia on field potentials in in vivo rats. METHODS These were measured on the skull over the right motor cortex of rats immediately after stimulating the left corpus callosum. RESULTS Evoked field potentials in the motor cortex were gradually increased for more than one hour after anodal tDCS. To induce these long-lasting effects, a sufficient duration of stimulation (20 minutes or more) was found to may be required rather than high stimulation intensity. CONCLUSION We propose that anodal tDCS with a sufficient duration of stimulation may modulate transcallosal plasticity.
Collapse
Affiliation(s)
- Ho Koo
- Department of Physiology, Wonkwang University College of Medicine, Iksan, South Korea
| | - Min Sun Kim
- Department of Physiology, Wonkwang University College of Medicine, Iksan, South Korea
| | - Sang Who Han
- Department of Physiology, Wonkwang University College of Medicine, Iksan, South Korea
| | - Walter Paulus
- University Medical Center, Department Clinical Neurophysiology, Georg-August-University, Goettingen, Germany
| | - Michael A Nitche
- University Medical Center, Department Clinical Neurophysiology, Georg-August-University, Goettingen, Germany; Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany; Department of Neurology, BG University Hospital Bergmannsheil, Ruhr-University Bochum, Germany
| | - Yun-Hee Kim
- Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Hyoung-Ihl Kim
- Department of Medical System Engineering & Department of Mechatronics, Gwangju Institute of Science and Technology, Gwangju, South Korea
| | - Sung-Hwa Ko
- Department of Rehabilitation Medicine, Pusan National University School of Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, South Korea
| | - Yong-Il Shin
- Department of Rehabilitation Medicine, Pusan National University School of Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, South Korea
| |
Collapse
|
16
|
Walton LR, Boustead NG, Carroll S, Wightman RM. Effects of Glutamate Receptor Activation on Local Oxygen Changes. ACS Chem Neurosci 2017; 8:1598-1608. [PMID: 28425701 PMCID: PMC5685152 DOI: 10.1021/acschemneuro.7b00088] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
![]()
Glutamate is ubiquitous
throughout the brain and serves as the
primary excitatory neurotransmitter. Neurons require energy to fire,
and energetic substrates (i.e., O2, glucose) are renewed
via cerebral blood flow (CBF) to maintain metabolic homeostasis. Magnetic
resonance brain functionality studies rely on the assumption that
CBF and neuronal activity are coupled consistently throughout the
brain; however, the origin of neuronal activity does not always coincide
with signals indicative of energy consumption (e.g., O2 decreases) at high spatial resolutions. Therefore, relationships
between excitatory neurotransmission and energy use must be evaluated
at higher resolutions. In this study, we showed that both endogenously
released and exogenously ejected glutamate decrease local tissue O2 concentrations, but whether hyperemic O2 restoration
followed depended on the stimulus method. Electrically stimulating
the glutamatergic corticostriatal pathway evoked biphasic O2 responses at striatal terminals: first O2 decreased,
then concentrations increased above baseline. Using iontophoresis
to locally eject ionotropic glutamate receptor antagonists revealed
that these receptors only influenced the O2 decrease. We
compared electrical stimulation to iontophoretic glutamate stimulation,
and measured concurrent single-unit activity and O2 to
limit both stimulation and recordings to <50 μm radius from
our sensor. Similarly, iontophoretic glutamate delivery elicited monophasic
O2 decreases without subsequent increases.
Collapse
Affiliation(s)
- Lindsay R. Walton
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Nick G. Boustead
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Susan Carroll
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - R. Mark Wightman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
- Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| |
Collapse
|
17
|
Sutherland BA, Fordsmann JC, Martin C, Neuhaus AA, Witgen BM, Piilgaard H, Lønstrup M, Couch Y, Sibson NR, Lauritzen M, Buchan AM. Multi-modal assessment of neurovascular coupling during cerebral ischaemia and reperfusion using remote middle cerebral artery occlusion. J Cereb Blood Flow Metab 2017; 37:2494-2508. [PMID: 27629101 PMCID: PMC5531347 DOI: 10.1177/0271678x16669512] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 08/08/2016] [Accepted: 08/09/2016] [Indexed: 12/28/2022]
Abstract
Hyperacute changes in cerebral blood flow during cerebral ischaemia and reperfusion are important determinants of injury. Cerebral blood flow is regulated by neurovascular coupling, and disruption of neurovascular coupling contributes to brain plasticity and repair problems. However, it is unknown how neurovascular coupling is affected hyperacutely during cerebral ischaemia and reperfusion. We have developed a remote middle cerebral artery occlusion model in the rat, which enables multi-modal assessment of neurovascular coupling immediately prior to, during and immediately following reperfusion. Male Wistar rats were subjected to remote middle cerebral artery occlusion, where a long filament was advanced intraluminally through a guide cannula in the common carotid artery. Transcallosal stimulation evoked increases in blood flow, tissue oxygenation and neuronal activity, which were diminished by middle cerebral artery occlusion and partially restored during reperfusion. These evoked responses were not affected by administration of the thrombolytic alteplase at clinically used doses. Evoked cerebral blood flow responses were fully restored at 24 h post-middle cerebral artery occlusion indicating that neurovascular dysfunction was not sustained. These data show for the first time that the rat remote middle cerebral artery occlusion model coupled with transcallosal stimulation provides a novel method for continuous assessment of hyperacute neurovascular coupling changes during ischaemia and reperfusion, and offers unique insight into hyperacute ischaemic pathophysiology.
Collapse
Affiliation(s)
- Brad A Sutherland
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- School of Medicine, Faculty of Health, University of Tasmania, Hobart, Australia
| | - Jonas C Fordsmann
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Chris Martin
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
- Department of Psychology, The University of Sheffield, Sheffield, UK
| | - Ain A Neuhaus
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Brent M Witgen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Henning Piilgaard
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Micael Lønstrup
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Yvonne Couch
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Nicola R Sibson
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Martin Lauritzen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark
| | | |
Collapse
|
18
|
Lecrux C, Hamel E. Neuronal networks and mediators of cortical neurovascular coupling responses in normal and altered brain states. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150350. [PMID: 27574304 PMCID: PMC5003852 DOI: 10.1098/rstb.2015.0350] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2016] [Indexed: 12/18/2022] Open
Abstract
Brain imaging techniques that use vascular signals to map changes in neuronal activity, such as blood oxygenation level-dependent functional magnetic resonance imaging, rely on the spatial and temporal coupling between changes in neurophysiology and haemodynamics, known as 'neurovascular coupling (NVC)'. Accordingly, NVC responses, mapped by changes in brain haemodynamics, have been validated for different stimuli under physiological conditions. In the cerebral cortex, the networks of excitatory pyramidal cells and inhibitory interneurons generating the changes in neural activity and the key mediators that signal to the vascular unit have been identified for some incoming afferent pathways. The neural circuits recruited by whisker glutamatergic-, basal forebrain cholinergic- or locus coeruleus noradrenergic pathway stimulation were found to be highly specific and discriminative, particularly when comparing the two modulatory systems to the sensory response. However, it is largely unknown whether or not NVC is still reliable when brain states are altered or in disease conditions. This lack of knowledge is surprising since brain imaging is broadly used in humans and, ultimately, in conditions that deviate from baseline brain function. Using the whisker-to-barrel pathway as a model of NVC, we can interrogate the reliability of NVC under enhanced cholinergic or noradrenergic modulation of cortical circuits that alters brain states.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
Collapse
Affiliation(s)
- C Lecrux
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, Quebec, Canada H3A 2B4
| | - E Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, Quebec, Canada H3A 2B4
| |
Collapse
|
19
|
Wei HS, Kang H, Rasheed IYD, Zhou S, Lou N, Gershteyn A, McConnell ED, Wang Y, Richardson KE, Palmer AF, Xu C, Wan J, Nedergaard M. Erythrocytes Are Oxygen-Sensing Regulators of the Cerebral Microcirculation. Neuron 2016; 91:851-862. [PMID: 27499087 DOI: 10.1016/j.neuron.2016.07.016] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 05/11/2016] [Accepted: 06/26/2016] [Indexed: 01/23/2023]
Abstract
Energy production in the brain depends almost exclusively on oxidative metabolism. Neurons have small energy reserves and require a continuous supply of oxygen (O2). It is therefore not surprising that one of the hallmarks of normal brain function is the tight coupling between cerebral blood flow and neuronal activity. Since capillaries are embedded in the O2-consuming neuropil, we have here examined whether activity-dependent dips in O2 tension drive capillary hyperemia. In vivo analyses showed that transient dips in tissue O2 tension elicit capillary hyperemia. Ex vivo experiments revealed that red blood cells (RBCs) themselves act as O2 sensors that autonomously regulate their own deformability and thereby flow velocity through capillaries in response to physiological decreases in O2 tension. This observation has broad implications for understanding how local changes in blood flow are coupled to synaptic transmission.
Collapse
Affiliation(s)
- Helen Shinru Wei
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Hongyi Kang
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Izad-Yar Daniel Rasheed
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Sitong Zhou
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Nanhong Lou
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Anna Gershteyn
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Evan Daniel McConnell
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Yixuan Wang
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; School of Mechanical Engineering, University of Science and Technology, Beijing 100083, China
| | - Kristopher Emil Richardson
- William G. Lowrie Department of Chemical & Biomolecular Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Andre Francis Palmer
- William G. Lowrie Department of Chemical & Biomolecular Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Chris Xu
- School of Applied & Engineering Physics, Cornell University, Ithaca, NY 14853, USA
| | - Jiandi Wan
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA.
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.
| |
Collapse
|
20
|
Tan A, Hu L, Tu Y, Chen R, Hung YS, Zhang Z. N1 Magnitude of Auditory Evoked Potentials and Spontaneous Functional Connectivity Between Bilateral Heschl's Gyrus Are Coupled at Interindividual Level. Brain Connect 2016; 6:496-504. [PMID: 27105665 DOI: 10.1089/brain.2016.0418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
N1 component of auditory evoked potentials is extensively used to investigate the propagation and processing of auditory inputs. However, the substantial interindividual variability of N1 could be a possible confounding factor when comparing different individuals or groups. Therefore, identifying the neuronal mechanism and origin of the interindividual variability of N1 is crucial in basic research and clinical applications. This study is aimed to use simultaneously recorded electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data to investigate the coupling between N1 and spontaneous functional connectivity (FC). EEG and fMRI data were simultaneously collected from a group of healthy individuals during a pure-tone listening task. Spontaneous FC was estimated from spontaneous blood oxygenation level-dependent (BOLD) signals that were isolated by regressing out task evoked BOLD signals from raw BOLD signals and then was correlated to N1 magnitude across individuals. It was observed that spontaneous FC between bilateral Heschl's gyrus was significantly and positively correlated with N1 magnitude across individuals (Spearman's R = 0.829, p < 0.001). The specificity of this observation was further confirmed by two whole-brain voxelwise analyses (voxel-mirrored homotopic connectivity analysis and seed-based connectivity analysis). These results enriched our understanding of the functional significance of the coupling between event-related brain responses and spontaneous brain connectivity, and hold the potential to increase the applicability of brain responses as a probe to the mechanism underlying pathophysiological conditions.
Collapse
Affiliation(s)
- Ao Tan
- 1 Department of Electrical and Electronic Engineering, The University of Hong Kong , Hong Kong, China
| | - Li Hu
- 2 Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China .,3 Faculty of Psychology, Southwest University , Chongqing, China
| | - Yiheng Tu
- 1 Department of Electrical and Electronic Engineering, The University of Hong Kong , Hong Kong, China
| | - Rui Chen
- 3 Faculty of Psychology, Southwest University , Chongqing, China
| | - Yeung Sam Hung
- 1 Department of Electrical and Electronic Engineering, The University of Hong Kong , Hong Kong, China
| | - Zhiguo Zhang
- 4 School of Data and Computer Science, Sun Yat-Sen University , Guangzhou, China
| |
Collapse
|
21
|
Abstract
Functional magnetic resonance imaging (fMRI) maps the spatiotemporal distribution of neural activity in the brain under varying cognitive conditions. Since its inception in 1991, blood oxygen level-dependent (BOLD) fMRI has rapidly become a vital methodology in basic and applied neuroscience research. In the clinical realm, it has become an established tool for presurgical functional brain mapping. This chapter has three principal aims. First, we review key physiologic, biophysical, and methodologic principles that underlie BOLD fMRI, regardless of its particular area of application. These principles inform a nuanced interpretation of the BOLD fMRI signal, along with its neurophysiologic significance and pitfalls. Second, we illustrate the clinical application of task-based fMRI to presurgical motor, language, and memory mapping in patients with lesions near eloquent brain areas. Integration of BOLD fMRI and diffusion tensor white-matter tractography provides a road map for presurgical planning and intraoperative navigation that helps to maximize the extent of lesion resection while minimizing the risk of postoperative neurologic deficits. Finally, we highlight several basic principles of resting-state fMRI and its emerging translational clinical applications. Resting-state fMRI represents an important paradigm shift, focusing attention on functional connectivity within intrinsic cognitive networks.
Collapse
Affiliation(s)
- Bradley R Buchbinder
- Department of Radiology, Division of Neuroradiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
22
|
Rosenegger DG, Gordon GR. A slow or modulatory role of astrocytes in neurovascular coupling. Microcirculation 2015; 22:197-203. [PMID: 25556627 DOI: 10.1111/micc.12184] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 12/16/2014] [Indexed: 11/30/2022]
Abstract
Astrocytes are thought to play an important role in NVC, a process that allows the brain to locally control blood flow in response to changes in activity. However, there is an ongoing debate as to when, and under what conditions astrocyte activity is required. In the following review we set forth the hypotheses that astrocytes: (i) act to modulate but not initiate functional hyperemia and (ii) help set the basal tone state of the brain microvasculature by the tonic release of vaso-active messengers. Through these actions astrocytes could help match metabolic demand with supply over a spectrum of activity timescales.
Collapse
Affiliation(s)
- David George Rosenegger
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | | |
Collapse
|
23
|
Bao P, Purington CJ, Tjan BS. Using an achiasmic human visual system to quantify the relationship between the fMRI BOLD signal and neural response. eLife 2015; 4. [PMID: 26613411 PMCID: PMC4764551 DOI: 10.7554/elife.09600] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/26/2015] [Indexed: 12/15/2022] Open
Abstract
Achiasma in humans causes gross mis-wiring of the retinal-fugal projection, resulting in overlapped cortical representations of left and right visual hemifields. We show that in areas V1-V3 this overlap is due to two co-located but non-interacting populations of neurons, each with a receptive field serving only one hemifield. Importantly, the two populations share the same local vascular control, resulting in a unique organization useful for quantifying the relationship between neural and fMRI BOLD responses without direct measurement of neural activity. Specifically, we can non-invasively double local neural responses by stimulating both neuronal populations with identical stimuli presented symmetrically across the vertical meridian to both visual hemifields, versus one population by stimulating in one hemifield. Measurements from a series of such doubling experiments show that the amplitude of BOLD response is proportional to approximately 0.5 power of the underlying neural response. Reanalyzing published data shows that this inferred relationship is general.
Collapse
Affiliation(s)
- Pinglei Bao
- Neuroscience Graduate Program, University of Southern California, Los Angeles, United States
| | - Christopher J Purington
- School of Optometry, University of California, Berkeley, Berkeley, CA, United States.,Vision Science Graduate Program, University of California, Berkeley, Berkeley, United States.,Department of Psychology, University of Southern California, Los Angeles, CA, United States
| | - Bosco S Tjan
- Neuroscience Graduate Program, University of Southern California, Los Angeles, United States.,Department of Psychology, University of Southern California, Los Angeles, CA, United States
| |
Collapse
|
24
|
Ayata C, Lauritzen M. Spreading Depression, Spreading Depolarizations, and the Cerebral Vasculature. Physiol Rev 2015; 95:953-93. [PMID: 26133935 DOI: 10.1152/physrev.00027.2014] [Citation(s) in RCA: 364] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Spreading depression (SD) is a transient wave of near-complete neuronal and glial depolarization associated with massive transmembrane ionic and water shifts. It is evolutionarily conserved in the central nervous systems of a wide variety of species from locust to human. The depolarization spreads slowly at a rate of only millimeters per minute by way of grey matter contiguity, irrespective of functional or vascular divisions, and lasts up to a minute in otherwise normal tissue. As such, SD is a radically different breed of electrophysiological activity compared with everyday neural activity, such as action potentials and synaptic transmission. Seventy years after its discovery by Leão, the mechanisms of SD and its profound metabolic and hemodynamic effects are still debated. What we did learn of consequence, however, is that SD plays a central role in the pathophysiology of a number of diseases including migraine, ischemic stroke, intracranial hemorrhage, and traumatic brain injury. An intriguing overlap among them is that they are all neurovascular disorders. Therefore, the interplay between neurons and vascular elements is critical for our understanding of the impact of this homeostatic breakdown in patients. The challenges of translating experimental data into human pathophysiology notwithstanding, this review provides a detailed account of bidirectional interactions between brain parenchyma and the cerebral vasculature during SD and puts this in the context of neurovascular diseases.
Collapse
Affiliation(s)
- Cenk Ayata
- Neurovascular Research Laboratory, Department of Radiology, and Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Neuroscience and Pharmacology and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; and Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark
| | - Martin Lauritzen
- Neurovascular Research Laboratory, Department of Radiology, and Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Neuroscience and Pharmacology and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; and Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark
| |
Collapse
|
25
|
Fabri M, Pierpaoli C, Barbaresi P, Polonara G. Functional topography of the corpus callosum investigated by DTI and fMRI. World J Radiol 2014; 6:895-906. [PMID: 25550994 PMCID: PMC4278150 DOI: 10.4329/wjr.v6.i12.895] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 09/02/2014] [Accepted: 10/29/2014] [Indexed: 02/06/2023] Open
Abstract
This short review examines the most recent functional studies of the topographic organization of the human corpus callosum, the main interhemispheric commissure. After a brief description of its anatomy, development, microstructure, and function, it examines and discusses the latest findings obtained using diffusion tensor imaging (DTI) and tractography (DTT) and functional magnetic resonance imaging (fMRI), three recently developed imaging techniques that have significantly expanded and refined our knowledge of the commissure. While DTI and DTT have been providing insights into its microstructure, integrity and level of myelination, fMRI has been the key technique in documenting the activation of white matter fibers, particularly in the corpus callosum. By combining DTT and fMRI it has been possible to describe the trajectory of the callosal fibers interconnecting the primary olfactory, gustatory, motor, somatic sensory, auditory and visual cortices at sites where the activation elicited by peripheral stimulation was detected by fMRI. These studies have demonstrated the presence of callosal fiber tracts that cross the commissure at the level of the genu, body, and splenium, at sites showing fMRI activation. Altogether such findings lend further support to the notion that the corpus callosum displays a functional topographic organization that can be explored with fMRI.
Collapse
|
26
|
BROŽÍČKOVÁ C, MIKULECKÁ A, OTÁHAL J. Effect of 7-Nitroindazole, a Neuronal Nitric Oxide Synthase Inhibitor, on Behavioral and Physiological Parameters. Physiol Res 2014; 63:637-48. [DOI: 10.33549/physiolres.932781] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The role of brain derived nitric oxide in the physiology and behavior remains disputable. One of the reasons of the controversies might be systemic side effects of nitric oxide synthase inhibitors. Therefore, under nNOS inhibition by 7-nitroindazole (7-NI) we carried out recordings of blood gasses, blood pressure and spontaneous EEG in conscious adult rats. Locomotion and spontaneous behavior were assessed in an open field. In addition skilled walking and limb coordination were evaluated using a ladder rung walking test. The blood gas analysis revealed a significant increase in pCO2 180 min and 240 min after the application of 7-NI. The power and entropy decreased simultaneously with a shift of the mean frequency of the spontaneous EEG toward slow oscillations after 7-NI treatment. The thresholds of evoked potentials underwent a significant drop and a trend towards a slight increase in the I-O curve slope was observed. 7-NI significantly suppressed open field behavior expressed as distance moved, exploratory rearing and grooming. As for the ladder rung walking test the 7-NI treated animals had more errors in foot placement indicating impairment in limb coordination. Therefore our findings suggest that 7-NI increased cortical excitability and altered some physiological and behavioral parameters.
Collapse
Affiliation(s)
| | | | - J. OTÁHAL
- Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| |
Collapse
|
27
|
Brožíčková C, Otáhal J. Effect of an inhibitor of neuronal nitric oxide synthase 7-nitroindazole on cerebral hemodynamic response and brain excitability in urethane-anesthetized rats. Physiol Res 2014; 62:S57-66. [PMID: 24329704 DOI: 10.33549/physiolres.932564] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The role of neuronal nitric oxide synthase (nNOS) in the pathophysiology of epilepsy and seizures remains disputable. One of the reasons why results from the acute in vivo studies display controversies might be the effect on the regulation of cerebral blood flow (CBF) during pharmacologically induced alterations of NO system. We examined neurovascular coupling in the rat sensorimotor cortex in response to transcallosal stimulation under nNOS inhibition by 7-nitroindazole (7-NI). Adult Wistar rats were anesthetized with urethane and epidural silver EEG electrodes were implanted over sensorimotor cortices. Regional CBF was measured by Laser Doppler Flowmetry (LDF). We catheterized a common carotid artery to measure arterial blood pressure (BP). 7-NI did not significantly affect blood pressure and heart rate. Electrophysiological recordings of evoked potentials (EPs) revealed no effect on their amplitude, rhythmic potentiation or depression of EPs. Transcallosal stimulation of the contralateral cortex induced a frequency dependent rise in CBF. Although 7-NI did not significantly affect basal CBF and cortical excitability, hemodynamic responses to the transcallosal stimulation were diminished implicating a role of nNOS in neurovascular coupling. Urethane anesthesia is suitable for future epileptological experiments. Our findings demonstrate that NO contributes to the hemodynamic response during brain activation.
Collapse
Affiliation(s)
- C Brožíčková
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| | | |
Collapse
|
28
|
Martin C. Contributions and complexities from the use of in vivo animal models to improve understanding of human neuroimaging signals. Front Neurosci 2014; 8:211. [PMID: 25191214 PMCID: PMC4137227 DOI: 10.3389/fnins.2014.00211] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 07/01/2014] [Indexed: 01/18/2023] Open
Abstract
Many of the major advances in our understanding of how functional brain imaging signals relate to neuronal activity over the previous two decades have arisen from physiological research studies involving experimental animal models. This approach has been successful partly because it provides opportunities to measure both the hemodynamic changes that underpin many human functional brain imaging techniques and the neuronal activity about which we wish to make inferences. Although research into the coupling of neuronal and hemodynamic responses using animal models has provided a general validation of the correspondence of neuroimaging signals to specific types of neuronal activity, it is also highlighting the key complexities and uncertainties in estimating neural signals from hemodynamic markers. This review will detail how research in animal models is contributing to our rapidly evolving understanding of what human neuroimaging techniques tell us about neuronal activity. It will highlight emerging issues in the interpretation of neuroimaging data that arise from in vivo research studies, for example spatial and temporal constraints to neuroimaging signal interpretation, or the effects of disease and modulatory neurotransmitters upon neurovascular coupling. We will also give critical consideration to the limitations and possible complexities of translating data acquired in the typical animals models used in this area to the arena of human fMRI. These include the commonplace use of anesthesia in animal research studies and the fact that many neuropsychological questions that are being actively explored in humans have limited homologs within current animal models for neuroimaging research. Finally we will highlighting approaches, both in experimental animals models (e.g. imaging in conscious, behaving animals) and human studies (e.g. combined fMRI-EEG), that mitigate against these challenges.
Collapse
Affiliation(s)
- Chris Martin
- Department of Psychology, The University of Sheffield Sheffield, UK
| |
Collapse
|
29
|
Urban A, Mace E, Brunner C, Heidmann M, Rossier J, Montaldo G. Chronic assessment of cerebral hemodynamics during rat forepaw electrical stimulation using functional ultrasound imaging. Neuroimage 2014; 101:138-49. [PMID: 25008960 DOI: 10.1016/j.neuroimage.2014.06.063] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/10/2014] [Accepted: 06/27/2014] [Indexed: 01/29/2023] Open
Abstract
Functional ultrasound imaging is a method recently developed to assess brain activity via hemodynamics in rodents. Doppler ultrasound signals allow the measurement of cerebral blood volume (CBV) and red blood cells' (RBCs') velocity in small vessels. However, this technique originally requires performing a large craniotomy that limits its use to acute experiments only. Moreover, a detailed description of the hemodynamic changes that underlie functional ultrasound imaging has not been described but is essential for a better interpretation of neuroimaging data. To overcome the limitation of the craniotomy, we developed a dedicated thinned skull surgery for chronic imaging. This procedure did not induce brain inflammation nor neuronal death as confirmed by immunostaining. We successfully acquired both high-resolution images of the microvasculature and functional movies of the brain hemodynamics on the same animal at 0, 2, and 7 days without loss of quality. Then, we investigated the spatiotemporal evolution of the CBV hemodynamic response function (HRF) in response to sensory-evoked electrical stimulus (1 mA) ranging from 1 (200 μs) to 25 pulses (5s). Our results indicate that CBV HRF parameters such as the peak amplitude, the time to peak, the full width at half-maximum and the spatial extent of the activated area increase with stimulus duration. Functional ultrasound imaging was sensitive enough to detect hemodynamic responses evoked by only a single pulse stimulus. We also observed that the RBC velocity during activation could be separated in two distinct speed ranges with the fastest velocities located in the upper part of the cortex and slower velocities in deeper layers. For the first time, functional ultrasound imaging demonstrates its potential to image brain activity chronically in small animals and offers new insights into the spatiotemporal evolution of cerebral hemodynamics.
Collapse
Affiliation(s)
- Alan Urban
- Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, INSERM S894, Centre Hospitalier Sainte-Anne, Paris, France.
| | - Emilie Mace
- 1A Allée des bois de Gagny, 93340 Le Raincy, France
| | - Clément Brunner
- Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, INSERM S894, Centre Hospitalier Sainte-Anne, Paris, France
| | - Marc Heidmann
- Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, INSERM S894, Centre Hospitalier Sainte-Anne, Paris, France
| | - Jean Rossier
- Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, INSERM S894, Centre Hospitalier Sainte-Anne, Paris, France
| | - Gabriel Montaldo
- Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, INSERM S894, Centre Hospitalier Sainte-Anne, Paris, France
| |
Collapse
|
30
|
Barbaresi P, Fabri M, Mensà E. Characterization of NO-producing neurons in the rat corpus callosum. Brain Behav 2014; 4:317-36. [PMID: 24944862 PMCID: PMC4055183 DOI: 10.1002/brb3.218] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 12/13/2013] [Accepted: 12/23/2013] [Indexed: 12/13/2022] Open
Abstract
INTRODUCTION The aim of this study was to determine the presence and distribution of nitric oxide (NO)-producing neurons in the rat corpus callosum (cc). MATERIAL AND METHODS To investigate this aspect of cc organization we used nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry and neuronal NO synthase (nNOS) immunocytochemistry. RESULTS Intense NADPH-d-positive (NADPH-d+) neurons were found along the rostrocaudal extension of the cc (sagittal sections). They were more numerous in the lateral cc and gradually decreased in the more medial regions, where they were very few or absent. The Golgi-like appearance of NADPH-d+ intracallosal neurons allowed dividing them into five morphological types: (1) bipolar; (2) fusiform; (3) round; (4) polygonal; and (5) pyramidal. The number of NADPH-d+ neurons (both hemispheres) was counted in two brains using 50-μm thick sections. In the first brain, counts involved 145 sections and neurons were 2959; in the second, 2227 neurons were counted in 130 sections. The distribution and morphology of nNOS-immunopositive (nNOSIP) neurons was identical to that of NADPH-d+neurons. Some of these neurons were observed in the cc ependymal region, where they might be in contact with cerebrospinal fluid (CSF), monitoring its composition, pH, and osmolality changes, or playing a role in regulating the synthesis and release of several peptides. The somatic, dendritic, and axonal processes of many NADPH-d+/nNOSIP neurons were closely associated with intracallosal blood vessels. CONCLUSIONS Such close relationship raises the possibility that these neurons are a major source of NO during neural activity. As NO is a potent vasodilator, these findings strongly suggest that NO-positive neurons transduce neuronal signals into vascular responses in selected cc regions, thus giving rise to hemodynamic changes detectable by neuroimaging.
Collapse
Affiliation(s)
- Paolo Barbaresi
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Marche Polytechnic University Ancona, I-60020, Italy
| | - Mara Fabri
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Marche Polytechnic University Ancona, I-60020, Italy
| | - Emanuela Mensà
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Marche Polytechnic University Ancona, I-60020, Italy
| |
Collapse
|
31
|
Abstract
The cerebrovascular regulation involves highly complex mechanisms to assure that the brain is perfused at all times. These mechanisms depend on all components of the neurovascular units: neurons, glia, and vascular cells. All these cell types can produce nitric oxide (NO), a powerful vasodilator through different NO synthases. Many studies underlined the key role of NO in the maintenance of resting cerebral blood flow (CBF) as well as in the mechanisms that control cerebrovascular tone: autoregulation and neurovascular coupling. However, although the role of NO in the control of CBF has been largely investigated, the complexity of the NO system and the lack of specific NO synthase inhibitors led to still unresolved questions such as the origin of NO and the pathways by which it controls the vascular tone. In this chapter, the role of NO in the regulation of CBF is critically reviewed and discussed in the context of the neurovascular unit and the general principles of cerebrovascular regulation.
Collapse
|
32
|
Otáhal J, Folbergrová J, Kovacs R, Kunz WS, Maggio N. Epileptic focus and alteration of metabolism. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 114:209-43. [PMID: 25078504 DOI: 10.1016/b978-0-12-418693-4.00009-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Epilepsy is one of the most common neurologic disorders affecting a substantial part of the population worldwide. Epileptic seizures represent the situation of increased neuronal activity associated with the enhanced demands for sufficient energy supply. For that purpose, very efficient regulatory mechanisms have to operate to ensure that cerebral blood flow, delivery of oxygen, and nutrients are continuously adapted to the local metabolic needs. The sophisticated regulation has to function in concert at several levels (systemic, tissue, cellular, and subcellular). Particularly, mitochondria play a key role not only in the energy production, but they are also central to many other processes including those leading to neuronal death. Impairment of any of the involved pathways can result in serious functional alterations, neurodegeneration, and potentially in epileptogenesis. The present review will address some of the important issues concerning vascular and metabolic changes in pathophysiology of epilepsy.
Collapse
Affiliation(s)
- Jakub Otáhal
- Institute of Physiology, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| | - Jaroslava Folbergrová
- Institute of Physiology, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Richard Kovacs
- Institute for Neurophysiology, Charité-Medical University Berlin, Berlin, Germany
| | - Wolfram S Kunz
- Department of Epileptology, University of Bonn, Bonn, Germany
| | - Nicola Maggio
- Department of Neurology, The Joseph Sagol Neuroscience Center, The Chaim Sheba Medical Center, Tel HaShomer, Israel; Talpiot Medical Leadership Program, The Chaim Sheba Medical Center, Tel HaShomer, Israel
| |
Collapse
|
33
|
Increased 20-HETE synthesis explains reduced cerebral blood flow but not impaired neurovascular coupling after cortical spreading depression in rat cerebral cortex. J Neurosci 2013; 33:2562-70. [PMID: 23392684 DOI: 10.1523/jneurosci.2308-12.2013] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cortical spreading depression (CSD) is associated with release of arachidonic acid, impaired neurovascular coupling, and reduced cerebral blood flow (CBF), caused by cortical vasoconstriction. We tested the hypothesis that the released arachidonic acid is metabolized by the cytochrome P450 enzyme to produce the vasoconstrictor 20-hydroxyeicosatetraenoic acid (20-HETE), and that this mechanism explains cortical vasoconstriction and vascular dysfunction after CSD. CSD was induced in the frontal cortex of rats and the cortical electrical activity and local field potentials recorded by glass microelectrodes, CBF by laser Doppler flowmetry, and tissue oxygen tension (tpO(2)) using polarographic microelectrodes. 20-HETE synthesis was measured in parallel experiments in cortical brain slices exposed to CSD. We used the specific inhibitor HET0016 (N-hydroxy-N'-(4-n-butyl-2-methylphenyl)formamidine) to block 20-HETE synthesis. CSD increased 20-HETE synthesis in brain slices for 120 min, and the time course of the increase in 20-HETE paralleled the reduction in CBF after CSD in vivo. HET0016 blocked the CSD-induced increase in 20-HETE synthesis and ameliorated the persistent reduction in CBF, but not the impaired neurovascular coupling after CSD. These findings suggest that CSD-induced increments in 20-HETE cause the reduction in CBF after CSD and that the attenuation of stimulation-induced CBF responses after CSD has a different mechanism. We suggest that blockade of 20-HETE synthesis may be clinically relevant to ameliorate reduced CBF in patients with migraine and acute brain cortex injuries.
Collapse
|
34
|
Unekawa M, Tomita Y, Toriumi H, Masamoto K, Kanno I, Suzuki N. Potassium-induced cortical spreading depression bilaterally suppresses the electroencephalogram but only ipsilaterally affects red blood cell velocity in intraparenchymal capillaries. J Neurosci Res 2013; 91:578-84. [DOI: 10.1002/jnr.23184] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 10/10/2012] [Accepted: 11/10/2012] [Indexed: 12/21/2022]
|
35
|
Argandoña EG, Bengoetxea H, Bulnes S, Rico-Barrio I, Ortuzar N, Lafuente JV. Effect of intracortical vascular endothelial growth factor infusion and blockade during the critical period in the rat visual cortex. Brain Res 2012; 1473:141-54. [DOI: 10.1016/j.brainres.2012.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Revised: 06/18/2012] [Accepted: 07/06/2012] [Indexed: 12/11/2022]
|
36
|
Duchemin S, Boily M, Sadekova N, Girouard H. The complex contribution of NOS interneurons in the physiology of cerebrovascular regulation. Front Neural Circuits 2012; 6:51. [PMID: 22907993 PMCID: PMC3414732 DOI: 10.3389/fncir.2012.00051] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 07/19/2012] [Indexed: 12/23/2022] Open
Abstract
Following the discovery of the vasorelaxant properties of nitric oxide (NO) by Furchgott and Ignarro, the finding by Bredt and coll. of a constitutively expressed NO synthase in neurons (nNOS) led to the presumption that neuronal NO may control cerebrovascular functions. Consequently, numerous studies have sought to determine whether neuraly-derived NO is involved in the regulation of cerebral blood flow (CBF). Anatomically, axons, dendrites, or somata of NO neurons have been found to contact the basement membrane of blood vessels or perivascular astrocytes in all segments of the cortical microcirculation. Functionally, various experimental approaches support a role of neuronal NO in the maintenance of resting CBF as well as in the vascular response to neuronal activity. Since decades, it has been assumed that neuronal NO simply diffuses to the local blood vessels and produce vasodilation through a cGMP-PKG dependent mechanism. However, NO is not the sole mediator of vasodilation in the cerebral microcirculation and is known to interact with a myriad of signaling pathways also involved in vascular control. In addition, cerebrovascular regulation is the result of a complex orchestration between all components of the neurovascular unit (i.e., neuronal, glial, and vascular cells) also known to produce NO. In this review article, the role of NO interneuron in the regulation of cortical microcirculation will be discussed in the context of the neurovascular unit.
Collapse
Affiliation(s)
- Sonia Duchemin
- Department of Pharmacology, Université de Montréal Montreal, QC, Canada
| | | | | | | |
Collapse
|
37
|
Neuronal inhibition and excitation, and the dichotomic control of brain hemodynamic and oxygen responses. Neuroimage 2012; 62:1040-50. [PMID: 22261372 DOI: 10.1016/j.neuroimage.2012.01.040] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 12/27/2011] [Accepted: 01/01/2012] [Indexed: 12/30/2022] Open
Abstract
Brain's electrical activity correlates strongly to changes in cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO(2)). Subthreshold synaptic processes correlate better than the spike rates of principal neurons to CBF, CMRO(2) and positive BOLD signals. Stimulation-induced rises in CMRO(2) are controlled by the ATP turnover, which depends on the energy used to fuel the Na,K-ATPase to reestablish ionic gradients, while stimulation-induced CBF responses to a large extent are controlled by mechanisms that depend on Ca(2+) rises in neurons and astrocytes. This dichotomy of metabolic and vascular control explains the gap between the stimulation-induced rises in CMRO(2) and CBF, and in turn the BOLD signal. Activity-dependent rises in CBF and CMRO(2) vary within and between brain regions due to differences in ATP turnover and Ca(2+)-dependent mechanisms. Nerve cells produce and release vasodilators that evoke positive BOLD signals, while the mechanisms that control negative BOLD signals by activity-dependent vasoconstriction are less well understood. Activation of both excitatory and inhibitory neurons produces rises in CBF and positive BOLD signals, while negative BOLD signals under most conditions correlate to excitation of inhibitory interneurons, but there are important exceptions to that rule as described in this paper. Thus, variations in the balance between synaptic excitation and inhibition contribute dynamically to the control of metabolic and hemodynamic responses, and in turn the amplitude and polarity of the BOLD signal. Therefore, it is not possible based on a negative or positive BOLD signal alone to decide whether the underlying activity goes on in principal or inhibitory neurons.
Collapse
|
38
|
Hypoxic regulation of the cerebral microcirculation is mediated by a carbon monoxide-sensitive hydrogen sulfide pathway. Proc Natl Acad Sci U S A 2012; 109:1293-8. [PMID: 22232681 DOI: 10.1073/pnas.1119658109] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Enhancement of cerebral blood flow by hypoxia is critical for brain function, but signaling systems underlying its regulation have been unclear. We report a pathway mediating hypoxia-induced cerebral vasodilation in studies monitoring vascular disposition in cerebellar slices and in intact mouse brains using two-photon intravital laser scanning microscopy. In this cascade, hypoxia elicits cerebral vasodilation via the coordinate actions of H(2)S formed by cystathionine β-synthase (CBS) and CO generated by heme oxygenase (HO)-2. Hypoxia diminishes CO generation by HO-2, an oxygen sensor. The constitutive CO physiologically inhibits CBS, and hypoxia leads to increased levels of H(2)S that mediate the vasodilation of precapillary arterioles. Mice with targeted deletion of HO-2 or CBS display impaired vascular responses to hypoxia. Thus, in intact adult brain cerebral cortex of HO-2-null mice, imaging mass spectrometry reveals an impaired ability to maintain ATP levels on hypoxia.
Collapse
|
39
|
Devonshire IM, Papadakis NG, Port M, Berwick J, Kennerley AJ, Mayhew JEW, Overton PG. Neurovascular coupling is brain region-dependent. Neuroimage 2011; 59:1997-2006. [PMID: 21982928 DOI: 10.1016/j.neuroimage.2011.09.050] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 09/15/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022] Open
Abstract
Despite recent advances in alternative brain imaging technologies, functional magnetic resonance imaging (fMRI) remains the workhorse for both medical diagnosis and primary research. Indeed, the number of research articles that utilise fMRI have continued to rise unabated since its conception in 1991, despite the limitation that recorded signals originate from the cerebral vasculature rather than neural tissue. Consequently, understanding the relationship between brain activity and the resultant changes in metabolism and blood flow (neurovascular coupling) remains a vital area of research. In the past, technical constraints have restricted investigations of neurovascular coupling to cortical sites and have led to the assumption that coupling in non-cortical structures is the same as in the cortex, despite the lack of any evidence. The current study investigated neurovascular coupling in the rat using whole-brain blood oxygenation level-dependent (BOLD) fMRI and multi-channel electrophysiological recordings and measured the response to a sensory stimulus as it proceeded through brainstem, thalamic and cortical processing sites - the so-called whisker-to-barrel pathway. We found marked regional differences in the amplitude of BOLD activation in the pathway and non-linear neurovascular coupling relationships in non-cortical sites. The findings have important implications for studies that use functional brain imaging to investigate sub-cortical function and caution against the use of simple, linear mapping of imaging signals onto neural activity.
Collapse
Affiliation(s)
- Ian M Devonshire
- Department of Psychology, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
40
|
Yokawa T. [phMRI (pharmacological MRI): application in drug development]. Nihon Yakurigaku Zasshi 2011; 138:117-121. [PMID: 21908939 DOI: 10.1254/fpj.138.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
|
41
|
van Meer MPA, van der Marel K, van der Sprenkel JWB, Dijkhuizen RM. MRI of bilateral sensorimotor network activation in response to direct intracortical stimulation in rats after unilateral stroke. J Cereb Blood Flow Metab 2011; 31:1583-7. [PMID: 21522166 PMCID: PMC3137478 DOI: 10.1038/jcbfm.2011.61] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Reinstatement of perilesional activation and connectivity may underlie functional recovery after stroke. To measure activation responsiveness in perilesional cortex in relation to white matter integrity, we performed functional functional magnetic resonance imaging during stimulation of the contralesional cortex, together with diffusion tensor imaging, 3 and 28 days after stroke in rats. Despite disturbed sensorimotor function and abnormal callosal appearance at day 3, activation amplitudes were preserved in the perilesional sensorimotor cortex, although time-to-peak was significantly delayed. This indicates that in spite of dysfunction, perilesional cortical tissue can be activated subacutely after stroke, while delay of the hemodynamic activation response suggests impaired neurovascular coupling.
Collapse
Affiliation(s)
- Maurits P A van Meer
- Biomedical MR Imaging and Spectroscopy Group, Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | | |
Collapse
|
42
|
Piilgaard H, Witgen BM, Rasmussen P, Lauritzen M. Cyclosporine A, FK506, and NIM811 ameliorate prolonged CBF reduction and impaired neurovascular coupling after cortical spreading depression. J Cereb Blood Flow Metab 2011; 31:1588-98. [PMID: 21427730 PMCID: PMC3137467 DOI: 10.1038/jcbfm.2011.28] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 02/16/2011] [Accepted: 02/17/2011] [Indexed: 11/08/2022]
Abstract
Cortical spreading depression (CSD) is associated with mitochondrial depolarization, increasing intracellular Ca(2+), and the release of free fatty acids, which favor opening of the mitochondrial permeability transition pore (mPTP) and activation of calcineurin (CaN). Here, we test the hypothesis that cyclosporine A (CsA), which blocks both mPTP and CaN, ameliorates the persistent reduction of cerebral blood flow (CBF), impaired vascular reactivity, and a persistent rise in the cerebral metabolic rate of oxygen (CMRO(2)) following CSD. In addition to CsA, we used the specific mPTP blocker NIM811 and the specific CaN blocker FK506. Cortical spreading depression was induced in rat frontal cortex. Electrocortical activity was recorded by glass microelectrodes, CBF by laser Doppler flowmetry, and tissue oxygen tension with polarographic microelectrodes. Electrocortical activity, basal CBF, CMRO(2), and neurovascular and neurometabolic coupling were unaffected by all three drugs under control conditions. NIM811 augmented the rise in CBF observed during CSD. Cyclosporine A and FK506 ameliorated the persistent decrease in CBF after CSD. All three drugs prevented disruption of neurovascular coupling after CSD; the rise in CMRO(2) was unchanged. Our data suggest that blockade of mPTP formation and CaN activation may prevent persistent CBF reduction and vascular dysfunction after CSD.
Collapse
Affiliation(s)
- Henning Piilgaard
- Department of Neuroscience and Pharmacology, Center for Healthy Aging, The Panum Institute, University of Copenhagen, Copenhagen N, Denmark
| | - Brent M Witgen
- Department of Neuroscience and Pharmacology, Center for Healthy Aging, The Panum Institute, University of Copenhagen, Copenhagen N, Denmark
| | - Peter Rasmussen
- Department of Neuroscience and Pharmacology, Center for Healthy Aging, The Panum Institute, University of Copenhagen, Copenhagen N, Denmark
| | - Martin Lauritzen
- Department of Neuroscience and Pharmacology, Center for Healthy Aging, The Panum Institute, University of Copenhagen, Copenhagen N, Denmark
- Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark
| |
Collapse
|
43
|
Goense J, Whittingstall K, Logothetis NK. Neural and BOLD responses across the brain. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2011; 3:75-86. [PMID: 26302473 DOI: 10.1002/wcs.153] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Functional Magnetic Resonance Imaging (fMRI) has quickly grown into one of the most important tools for studying brain function, especially in humans. Despite its prevalence, we still do not have a clear picture of what exactly the blood oxygenation level dependent (BOLD) signal represents or how it compares to the signals obtained with other methods (e.g., electrophysiology). We particularly refer to single neuron recordings and electroencephalography when we mention 'electrophysiological methods', given that these methods have been used for more than 50 years, and have formed the basis of much of our current understanding of brain function. Brain function involves the coordinated activity of many different areas and many different cell types that can participate in an enormous variety of processes (neural firing, inhibitory and excitatory synaptic activity, neuromodulation, oscillatory activity, etc.). Of these cells and processes, only a subset is sampled with electrophysiological techniques, and their contribution to the recorded signals is not exactly known. Functional imaging signals are driven by the metabolic needs of the active cells, and are most likely also biased toward certain cell types and certain neural processes, although we know even less about which processes actually drive the hemodynamic response. This article discusses the current status on the interpretation of the BOLD signal and how it relates to neural activity measured with electrophysiological techniques. WIREs Cogn Sci 2012, 3:75-86. doi: 10.1002/wcs.153 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Jozien Goense
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Kevin Whittingstall
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Nikos K Logothetis
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom
| |
Collapse
|
44
|
Radhakrishnan H, Wu W, Boas D, Franceschini MA. Study of neurovascular coupling by modulating neuronal activity with GABA. Brain Res 2010; 1372:1-12. [PMID: 21145313 DOI: 10.1016/j.brainres.2010.11.082] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 11/05/2010] [Accepted: 11/24/2010] [Indexed: 10/18/2022]
Abstract
Fundamental to the interpretation of neurovascular coupling is determining the neuronal activity that accounts for functional hyperemia. Recently, synaptic and not spiking activity has been found to be responsible for the hemodynamic response. Using pharmacological manipulation in rats, we want to further determine whether the cortical synaptic activity generated by the thalamic input or the subsequent synaptic activity related to secondary cortical processing is driving the hemodynamic response. In this study, we topically applied γ-aminobutyric acid (GABA) in the somatosensory cortex and used electrical forepaw stimulation to evoke neural and vascular activity. In a group of 8 animals, using laminar electrophysiology, we verified that topical application of GABA for 20min does not affect layer IV synaptic activity but reduces subsequent activity in the supragranular and infragranular layers. In another group of 8 animals, we simultaneously measured the electrical and vascular responses with scalp electroencephalography (EEG) and diffuse optical imaging (DOI), respectively. We decomposed somatosensory evoked potentials (SEP) into three major components: P1, N1, and P2, where P1 represents the thalamic input activity originating in layer IV and N1 and P2 represent the subsequent cortical transmissions. We verified that GABA infusion in the somatosensory cortex does not significantly reduce the P1 SEP component but strongly reduces the N1 and P2 components. We found that GABA also elicits a large reduction in the hemodynamic responses, which correlate with the reduction in N1 and P2 components. These results suggest that the hemodynamic response is predominantly driven by cortico-cortical interactions and not by the initial thalamocortical activity in layer IV.
Collapse
Affiliation(s)
- Harsha Radhakrishnan
- MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA.
| | | | | | | |
Collapse
|
45
|
Hahn T, Heinzel S, Plichta MM, Reif A, Lesch KP, Fallgatter AJ. Neurovascular Coupling in the Human Visual Cortex Is Modulated by Cyclooxygenase-1 (COX-1) Gene Variant. Cereb Cortex 2010; 21:1659-66. [DOI: 10.1093/cercor/bhq236] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
|
46
|
Attwell D, Buchan AM, Charpak S, Lauritzen M, Macvicar BA, Newman EA. Glial and neuronal control of brain blood flow. Nature 2010; 468:232-43. [PMID: 21068832 PMCID: PMC3206737 DOI: 10.1038/nature09613] [Citation(s) in RCA: 1644] [Impact Index Per Article: 117.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches.
Collapse
Affiliation(s)
- David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
| | | | | | | | | | | |
Collapse
|
47
|
Cauli B, Hamel E. Revisiting the role of neurons in neurovascular coupling. FRONTIERS IN NEUROENERGETICS 2010; 2:9. [PMID: 20616884 PMCID: PMC2899521 DOI: 10.3389/fnene.2010.00009] [Citation(s) in RCA: 174] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 05/26/2010] [Indexed: 11/13/2022]
Abstract
In this article, we will review molecular, anatomical, physiological and pharmacological data in an attempt to better understand how excitatory and inhibitory neurons recruited by distinct afferent inputs to the cerebral cortex contribute to the coupled hemodynamic response, and how astrocytes can act as intermediaries to these neuronal populations. We aim at providing the pros and cons to the following statements that, depending on the nature of the afferent input to the neocortex, (i) different neuronal or astroglial messengers, likely acting in sequence, mediate the hemodynamic changes, (ii) some recruited neurons release messengers that directly alter blood vessel tone, (iii) others act by modulating neuronal and astroglial activity, and (iv) astrocytes act as intermediaries for both excitatory and inhibitory neurotransmitters. We will stress that a given afferent signal activates a precise neuronal circuitry that determines the mediators of the hemodynamic response as well as the level of interaction with surrounding astrocytes.
Collapse
Affiliation(s)
- Bruno Cauli
- Laboratoire de Neurobiologie des Processus Adaptatifs, Université Pierre et Marie Curie Paris, France
| | | |
Collapse
|
48
|
Franceschini MA, Radhakrishnan H, Thakur K, Wu W, Ruvinskaya S, Carp S, Boas DA. The effect of different anesthetics on neurovascular coupling. Neuroimage 2010; 51:1367-77. [PMID: 20350606 DOI: 10.1016/j.neuroimage.2010.03.060] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 03/01/2010] [Accepted: 03/20/2010] [Indexed: 02/03/2023] Open
Abstract
To date, the majority of neurovascular coupling studies focused on the thalamic afferents' activity in layer IV and the corresponding large spiking activity as responsible for functional hyperemia. This paper highlights the role of the secondary and late cortico-cortical transmission in neurovascular coupling. Simultaneous scalp electroencephalography (EEG) and diffuse optical imaging (DOI) measurements were obtained during multiple conditions of event-related electrical forepaw stimulation in 33 male Sprague-Dawley rats divided into 6 groups depending on the maintaining anesthetic - alpha-chloralose, pentobarbital, ketamine-xylazine, fentanyl-droperidol, isoflurane, or propofol. The somatosensory evoked potentials (SEP) were decomposed into four components and the question of which best predicts the hemodynamic responses was investigated. Results of the linear regression analysis show that the hemodynamic response is best correlated with the secondary and late cortico-cortical transmissions and not with the initial thalamic input activity in layer IV. Baseline cerebral blood flow (CBF) interacts with neural activity and influences the evoked hemodynamic responses. Finally, neurovascular coupling appears to be the same across all anesthetics used.
Collapse
Affiliation(s)
- Maria Angela Franceschini
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, USA.
| | | | | | | | | | | | | |
Collapse
|
49
|
Leithner C, Royl G, Offenhauser N, Füchtemeier M, Kohl-Bareis M, Villringer A, Dirnagl U, Lindauer U. Pharmacological uncoupling of activation induced increases in CBF and CMRO2. J Cereb Blood Flow Metab 2010; 30:311-22. [PMID: 19794398 PMCID: PMC2949119 DOI: 10.1038/jcbfm.2009.211] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Neurovascular coupling provides the basis for many functional neuroimaging techniques. Nitric oxide (NO), adenosine, cyclooxygenase, CYP450 epoxygenase, and potassium are involved in dilating arterioles during neuronal activation. We combined inhibition of NO synthase, cyclooxygenase, adenosine receptors, CYP450 epoxygenase, and inward rectifier potassium (Kir) channels to test whether these pathways could explain the blood flow response to neuronal activation. Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO(2)) of the somatosensory cortex were measured during forepaw stimulation in 24 rats using a laser Doppler/spectroscopy probe through a cranial window. Combined inhibition reduced CBF responses by two-thirds, somatosensory evoked potentials and activation-induced CMRO(2) increases remained unchanged, and deoxy-hemoglobin (deoxy-Hb) response was abrogated. This shows that in the rat somatosensory cortex, one-third of the physiological blood flow increase is sufficient to prevent microcirculatory increase of deoxy-Hb concentration during neuronal activity. The large physiological CBF response is not necessary to support small changes in CMRO(2). We speculate that the CBF response safeguards substrate delivery during functional activation with a considerable 'safety factor'. Reduction of the CBF response in pathological states may abolish the BOLD-fMRI signal, without affecting underlying neuronal activity.
Collapse
Affiliation(s)
- Christoph Leithner
- Department of Experimental Neurology, Charité Universitätsmedizin, Center for Stroke Research Berlin, Berlin, Germany
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Linear and nonlinear relationships between visual stimuli, EEG and BOLD fMRI signals. Neuroimage 2010; 50:1054-66. [PMID: 20079854 DOI: 10.1016/j.neuroimage.2010.01.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 01/05/2010] [Accepted: 01/07/2010] [Indexed: 11/23/2022] Open
Abstract
In the present study, the cascaded interactions between stimuli and neural and hemodynamic responses were modeled using linear systems. These models provided the theoretical hypotheses that were tested against the electroencephalography (EEG) and blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) data recorded from human subjects during prolonged periods of repeated visual stimuli with a variable setting of the inter-stimulus interval (ISI) and visual contrast. Our results suggest that (1) neural response is nonlinear only when ISI<0.2 s, (2) BOLD response is nonlinear with an exclusively vascular origin when 0.25<ISI<4.2 s, (3) vascular response nonlinearity reflects a refractory effect, rather than a ceiling effect, and (4) there is a strong linear relationship between the BOLD effect size and the integrated power of event-related synaptic current activity, after modeling and taking into account the vascular refractory effect. These conclusions offer important insights into the origins of BOLD nonlinearity and the nature of neurovascular coupling, and suggest an effective means to quantitatively interpret the BOLD signal in terms of neural activity. The validated cross-modal relationship between fMRI and EEG may provide a theoretical basis for the integration of these two modalities.
Collapse
|