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Natsubori A, Kwon S, Honda Y, Kojima T, Karashima A, Masamoto K, Honda M. Serotonergic regulation of cortical neurovascular coupling and hemodynamics upon awakening from sleep in mice. J Cereb Blood Flow Metab 2024; 44:1591-1607. [PMID: 38477254 DOI: 10.1177/0271678x241238843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Neurovascular coupling (NVC) is the functional hyperemia of the brain responding to local neuronal activity. It is mediated by astrocytes and affected by subcortical ascending pathways in the cortex that convey information, such as sensory stimuli and the animal condition. Here, we investigate the influence of the raphe serotonergic system, a subcortical ascending arousal system in animals, on the modulation of cortical NVC and cerebral blood flow (CBF). Raphe serotonergic neurons were optogenically activated for 30 s, which immediately awakened the mice from non-rapid eye movement sleep. This caused a biphasic cortical hemodynamic change: a transient increase for a few seconds immediately after photostimulation onset, followed by a large progressive decrease during the stimulation period. Serotonergic neuron activation increased intracellular Ca2+ levels in cortical pyramidal neurons and astrocytes, demonstrating its effect on the NVC components. Pharmacological inhibition of cortical neuronal firing activity and astrocyte metabolic activity had small hypovolemic effects on serotonin-induced biphasic CBF changes, while blocking 5-HT1B receptors expressed primarily in cerebral vasculature attenuated the decreasing CBF phase. This suggests that serotonergic neuron activation leading to animal awakening could allow the NVC to exert a hyperemic function during a biphasic CBF response, with a predominant decrease in the cortex.
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Affiliation(s)
- Akiyo Natsubori
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Soojin Kwon
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Yoshiko Honda
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Takashi Kojima
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Akihiro Karashima
- Department of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, Sendai, Japan
| | - Kazuto Masamoto
- Dept. Mechanical and Intelligent Systems Engineering, Univ. of Electro-Communications, Tokyo, Japan
| | - Makoto Honda
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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Cerri DH, Albaugh DL, Walton LR, Katz B, Wang TW, Chao THH, Zhang W, Nonneman RJ, Jiang J, Lee SH, Etkin A, Hall CN, Stuber GD, Shih YYI. Distinct neurochemical influences on fMRI response polarity in the striatum. Nat Commun 2024; 15:1916. [PMID: 38429266 PMCID: PMC10907631 DOI: 10.1038/s41467-024-46088-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 02/13/2024] [Indexed: 03/03/2024] Open
Abstract
The striatum, known as the input nucleus of the basal ganglia, is extensively studied for its diverse behavioral roles. However, the relationship between its neuronal and vascular activity, vital for interpreting functional magnetic resonance imaging (fMRI) signals, has not received comprehensive examination within the striatum. Here, we demonstrate that optogenetic stimulation of dorsal striatal neurons or their afferents from various cortical and subcortical regions induces negative striatal fMRI responses in rats, manifesting as vasoconstriction. These responses occur even with heightened striatal neuronal activity, confirmed by electrophysiology and fiber-photometry. In parallel, midbrain dopaminergic neuron optogenetic modulation, coupled with electrochemical measurements, establishes a link between striatal vasodilation and dopamine release. Intriguingly, in vivo intra-striatal pharmacological manipulations during optogenetic stimulation highlight a critical role of opioidergic signaling in generating striatal vasoconstriction. This observation is substantiated by detecting striatal vasoconstriction in brain slices after synthetic opioid application. In humans, manipulations aimed at increasing striatal neuronal activity likewise elicit negative striatal fMRI responses. Our results emphasize the necessity of considering vasoactive neurotransmission alongside neuronal activity when interpreting fMRI signal.
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Affiliation(s)
- Domenic H Cerri
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Daniel L Albaugh
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Lindsay R Walton
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Brittany Katz
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Tzu-Wen Wang
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Tzu-Hao Harry Chao
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Weiting Zhang
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Randal J Nonneman
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jing Jiang
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA
- Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, USA
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Sung-Ho Lee
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Amit Etkin
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA
- Alto Neuroscience, Los Altos, CA, USA
| | - Catherine N Hall
- Sussex Neuroscience, University of Sussex, Falmer, United Kingdom
- School of Psychology, University of Sussex, Falmer, United Kingdom
| | - Garret D Stuber
- Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
- Department of Pharmacology, University of Washington, Seattle, WA, USA
| | - Yen-Yu Ian Shih
- Center for Animal MRI, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Biomedical Research Imaging Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Neurology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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3
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Lee JY, You T, Woo CW, Kim SG. Optogenetic fMRI for Brain-Wide Circuit Analysis of Sensory Processing. Int J Mol Sci 2022; 23:ijms232012268. [PMID: 36293125 PMCID: PMC9602603 DOI: 10.3390/ijms232012268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/12/2022] [Accepted: 10/12/2022] [Indexed: 11/20/2022] Open
Abstract
Sensory processing is a complex neurological process that receives, integrates, and responds to information from one's own body and environment, which is closely related to survival as well as neurological disorders. Brain-wide networks of sensory processing are difficult to investigate due to their dynamic regulation by multiple brain circuits. Optogenetics, a neuromodulation technique that uses light-sensitive proteins, can be combined with functional magnetic resonance imaging (ofMRI) to measure whole-brain activity. Since ofMRI has increasingly been used for investigating brain circuits underlying sensory processing for over a decade, we systematically reviewed recent ofMRI studies of sensory circuits and discussed the challenges of optogenetic fMRI in rodents.
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Affiliation(s)
- Jeong-Yun Lee
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Korea
| | - Taeyi You
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon 16419, Korea
| | - Choong-Wan Woo
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon 16419, Korea
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon 16419, Korea
- Correspondence: ; Tel.: +82-31-299-4350; Fax: +82-31-299-4506
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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.
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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,
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5
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Chan RW, Cron GO, Asaad M, Edelman BJ, Lee HJ, Adesnik H, Feinberg D, Lee JH. Distinct local and brain-wide networks are activated by optogenetic stimulation of neurons specific to each layer of motor cortex. Neuroimage 2022; 263:119640. [PMID: 36176220 PMCID: PMC10025169 DOI: 10.1016/j.neuroimage.2022.119640] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 09/13/2022] [Accepted: 09/19/2022] [Indexed: 11/20/2022] Open
Abstract
Primary motor cortex (M1) consists of a stack of interconnected but distinct layers (L1-L6) which affect motor control through large-scale networks. However, the brain-wide functional influence of each layer is poorly understood. We sought to expand our knowledge of these layers' circuitry by combining Cre-driver mouse lines, optogenetics, fMRI, and electrophysiology. Neuronal activities initiated in Drd3 neurons (within L2/3) were mainly confined within M1, while stimulation of Scnn1a, Rbp4, and Ntsr1 neurons (within L4, L5, and L6, respectively) evoked distinct responses in M1 and motor-related subcortical regions, including striatum and motor thalamus. We also found that fMRI responses from targeted stimulations correlated with both local field potentials (LFPs) and spike changes. This study represents a step forward in our understanding of how different layers of primary motor cortex are embedded in brain-wide circuitry.
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Affiliation(s)
- Russell W Chan
- Department of Neurology and Neurological Sciences, Stanford University, CA 94305, USA
| | - Greg O Cron
- Department of Neurology and Neurological Sciences, Stanford University, CA 94305, USA
| | - Mazen Asaad
- Department of Molecular and Cellular Physiology, Stanford University, CA 94305, USA
| | - Bradley J Edelman
- Department of Neurology and Neurological Sciences, Stanford University, CA 94305, USA
| | - Hyun Joo Lee
- Department of Neurology and Neurological Sciences, Stanford University, CA 94305, USA
| | - Hillel Adesnik
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - David Feinberg
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Jin Hyung Lee
- Department of Neurology and Neurological Sciences, Stanford University, CA 94305, USA; Department of Bioengineering, Stanford University, CA 94305, USA; Department of Neurosurgery, Stanford University, CA 94305, USA; Department of Electrical Engineering, Stanford University, CA 94305, USA.
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6
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Ioanas HI, Schlegel F, Skachokova Z, Schroeter A, Husak T, Rudin M. Hybrid fiber optic-fMRI for multimodal cell-specific recording and manipulation of neural activity in rodents. NEUROPHOTONICS 2022; 9:032206. [PMID: 35355657 PMCID: PMC8936941 DOI: 10.1117/1.nph.9.3.032206] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 01/19/2022] [Indexed: 05/08/2023]
Abstract
Significance: Multiscale imaging holds particular relevance to neuroscience, where it helps integrate the cellular and molecular biological scale, which is most accessible to interventions, with holistic organ-level evaluations, most relevant with respect to function. Being inextricably interdisciplinary, multiscale imaging benefits substantially from incremental technology adoption, and a detailed overview of the state-of-the-art is vital to an informed application of imaging methods. Aim: In this article, we lay out the background and methodological aspects of multimodal approaches combining functional magnetic resonance imaging (fMRI) with simultaneous optical measurement or stimulation. Approach: We focus on optical techniques as these allow, in conjunction with genetically encoded proteins (e.g. calcium indicators or optical signal transducers), unprecedented read-out and control specificity for individual cell-types during fMRI experiments, while leveraging non-interfering modalities. Results: A variety of different solutions for optical/fMRI methods has been reported ranging from bulk fluorescence recordings via fiber photometry to high resolution microscopy. In particular, the plethora of optogenetic tools has enabled the transformation of stimulus-evoked fMRI into a cell biological interrogation method. We discuss the capabilities and limitations of these genetically encoded molecular tools in the study of brain phenomena of great methodological and neuropsychiatric interest-such as neurovascular coupling (NVC) and neuronal network mapping. We provide a methodological description of this interdisciplinary field of study, and focus in particular on the limitations of the widely used blood oxygen level dependent (BOLD) signal and how multimodal readouts can shed light on the contributions arising from neurons, astrocytes, or the vasculature. Conclusion: We conclude that information from multiple signaling pathways must be incorporated in future forward models of the BOLD response to prevent erroneous conclusions when using fMRI as a surrogate measure for neural activity. Further, we highlight the potential of direct neuronal stimulation via genetically defined brain networks towards advancing neurophysiological understanding and better estimating effective connectivity.
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Affiliation(s)
- Horea-Ioan Ioanas
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
- Massachusetts Institute of Technology, Department of Biological Engineering, Cambridge, Massachusetts, United States
- Dartmouth College, Center for Open Neuroscience, Hanover, New Hampshire, United States
- Address all correspondence to Markus Rudin, ; Horea-Ioan Ioanas,
| | - Felix Schlegel
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
| | - Zhiva Skachokova
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
| | - Aileen Schroeter
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
- University of Zurich, USZ Innovation Hub, Zurich, Switzerland
| | - Tetiana Husak
- Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, Cambridge, Massachusetts, United States
| | - Markus Rudin
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
- The LOOP Zurich, Zurich, Switzerland
- Address all correspondence to Markus Rudin, ; Horea-Ioan Ioanas,
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7
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Beloate LN, Zhang N. Connecting the dots between cell populations, whole-brain activity, and behavior. NEUROPHOTONICS 2022; 9:032208. [PMID: 35350137 PMCID: PMC8957372 DOI: 10.1117/1.nph.9.3.032208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Simultaneously manipulating and monitoring both microscopic and macroscopic brain activity in vivo and identifying the linkage to behavior are powerful tools in neuroscience research. These capabilities have been realized with the recent technical advances of optogenetics and its combination with fMRI, here termed "opto-fMRI." Opto-fMRI allows for targeted brain region-, cell-type-, or projection-specific manipulation and targeted Ca 2 + activity measurement to be linked with global brain signaling and behavior. We cover the history, technical advances, applications, and important considerations of opto-fMRI in anesthetized and awake rodents and the future directions of the combined techniques in neuroscience and neuroimaging.
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Affiliation(s)
- Lauren N. Beloate
- Pennsylvania State University, Department of Biomedical Engineering, Pennsylvania, United States
| | - Nanyin Zhang
- Pennsylvania State University, Department of Biomedical Engineering, Pennsylvania, United States
- Pennsylvania State University, Huck Institutes of the Life Sciences, Pennsylvania, United States
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8
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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.
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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.)
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9
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Contribution of animal models toward understanding resting state functional connectivity. Neuroimage 2021; 245:118630. [PMID: 34644593 DOI: 10.1016/j.neuroimage.2021.118630] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 08/06/2021] [Accepted: 09/29/2021] [Indexed: 12/27/2022] Open
Abstract
Functional connectivity, which reflects the spatial and temporal organization of intrinsic activity throughout the brain, is one of the most studied measures in human neuroimaging research. The noninvasive acquisition of resting state functional magnetic resonance imaging (rs-fMRI) allows the characterization of features designated as functional networks, functional connectivity gradients, and time-varying activity patterns that provide insight into the intrinsic functional organization of the brain and potential alterations related to brain dysfunction. Functional connectivity, hence, captures dimensions of the brain's activity that have enormous potential for both clinical and preclinical research. However, the mechanisms underlying functional connectivity have yet to be fully characterized, hindering interpretation of rs-fMRI studies. As in other branches of neuroscience, the identification of the neurophysiological processes that contribute to functional connectivity largely depends on research conducted on laboratory animals, which provide a platform where specific, multi-dimensional investigations that involve invasive measurements can be carried out. These highly controlled experiments facilitate the interpretation of the temporal correlations observed across the brain. Indeed, information obtained from animal experimentation to date is the basis for our current understanding of the underlying basis for functional brain connectivity. This review presents a compendium of some of the most critical advances in the field based on the efforts made by the animal neuroimaging community.
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10
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Moon HS, Jiang H, Vo TT, Jung WB, Vazquez AL, Kim SG. Contribution of Excitatory and Inhibitory Neuronal Activity to BOLD fMRI. Cereb Cortex 2021; 31:4053-4067. [PMID: 33895810 PMCID: PMC8328221 DOI: 10.1093/cercor/bhab068] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The BOLD fMRI response in the cortex is often assumed to reflect changes in excitatory neural activity. However, the contribution of inhibitory neurons to BOLD fMRI is unclear. Here, the role of inhibitory and excitatory activity was examined using multimodal approaches: electrophysiological recording, 15.2 T fMRI, optical intrinsic signal imaging, and modeling. Inhibitory and excitatory neuronal activity in the somatosensory cortex were selectively modulated by 20-s optogenetic stimulation of VGAT-ChR2 and CaMKII-ChR2 mice, respectively. Somatosensory stimulation and optogenetic stimulation of excitatory neurons induced positive BOLD responses in the somatosensory network, whereas stimulation of inhibitory neurons produced biphasic responses at the stimulation site, initial positive and later negative BOLD signals, and negative BOLD responses at downstream sites. When the stimulation duration was reduced to 5 s, the hemodynamic response of VGAT-ChR2 mice to optogenetic stimulation was only positive. Lastly, modeling performed from neuronal and hemodynamic data shows that the hemodynamic response function (HRF) of excitatory neurons is similar across different conditions, whereas the HRF of inhibitory neurons is highly sensitive to stimulation frequency and peaks earlier than that of excitatory neurons. Our study provides insights into the neurovascular coupling of excitatory and inhibitory neurons and the interpretation of BOLD fMRI signals.
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Affiliation(s)
- Hyun Seok Moon
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.,Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Haiyan Jiang
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Thanh Tan Vo
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.,Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Won Beom Jung
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
| | - Alberto L Vazquez
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15203, USA.,Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.,Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
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11
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Lee J, Stile CL, Bice AR, Rosenthal ZP, Yan P, Snyder AZ, Lee JM, Bauer AQ. Opposed hemodynamic responses following increased excitation and parvalbumin-based inhibition. J Cereb Blood Flow Metab 2021; 41:841-856. [PMID: 33736512 PMCID: PMC7983494 DOI: 10.1177/0271678x20930831] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 03/24/2020] [Accepted: 04/30/2020] [Indexed: 02/05/2023]
Abstract
Understanding cellular contributions to hemodynamic activity is essential for interpreting blood-based brain mapping signals. Optogenetic studies examining cell-specific influences on local hemodynamics have reported that excitatory activity results in cerebral perfusion and blood volume increase, while inhibitory activity contributes to both vasodilation and vasoconstriction. How specific subpopulations of interneurons regulate the brain's blood supply is less examined. Parvalbumin interneurons are the largest subpopulation of GABAergic neurons in the brain, critical for brain development, plasticity, and long-distance excitatory neurotransmission. Despite their essential role in brain function, the contribution of parvalbumin neurons to neurovascular coupling has been relatively unexamined. Using optical intrinsic signal imaging and laser speckle contrast imaging, we photostimulated awake and anesthetized transgenic mice expressing channelrhodopsin under a parvalbumin promoter. Increased parvalbumin activity reduced local oxygenation, cerebral blood volume, and cerebral blood flow. These "negative" hemodynamic responses were consistent within and across mice and reproducible across a broad range of photostimulus parameters. However, the sign and magnitude of the hemodynamic response resulting from increased parvalbumin activity depended on the type and level of anesthesia used. Opposed hemodynamic responses following increased excitation or parvalbumin-based inhibition suggest unique contributions from different cell populations to neurovascular coupling.
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Affiliation(s)
- Joonhyuk Lee
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Chloe L Stile
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Annie R Bice
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Zachary P Rosenthal
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Ping Yan
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Abraham Z Snyder
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jin-Moo Lee
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO, USA
| | - Adam Q Bauer
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO, USA
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12
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Poplawsky AJ, Iordanova B, Vazquez AL, Kim SG, Fukuda M. Postsynaptic activity of inhibitory neurons evokes hemodynamic fMRI responses. Neuroimage 2021; 225:117457. [PMID: 33069862 PMCID: PMC7818351 DOI: 10.1016/j.neuroimage.2020.117457] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/15/2020] [Accepted: 10/12/2020] [Indexed: 02/08/2023] Open
Abstract
Functional MRI responses are localized to the synaptic sites of evoked inhibitory neurons, but it is unknown whether, or by what mechanisms, these neurons initiate functional hyperemia. Here, the neuronal origins of these hemodynamic responses were investigated by fMRI or local field potential and blood flow measurements during topical application of pharmacological agents when GABAergic granule cells in the rat olfactory bulb were synaptically targeted. First, to examine if postsynaptic activation of these inhibitory neurons was required for neurovascular coupling, we applied an NMDA receptor antagonist during cerebral blood volume-weighted fMRI acquisition and found that responses below the drug application site (up to ~1.5 mm) significantly decreased within ~30 min. Similarly, large decreases in granule cell postsynaptic activities and blood flow responses were observed when AMPA or NMDA receptor antagonists were applied. Second, inhibition of nitric oxide synthase preferentially decreased the initial, fast component of the blood flow response, while inhibitors of astrocyte-specific glutamate transporters and vasoactive intestinal peptide receptors did not decrease blood flow responses. Third, inhibition of GABA release with a presynaptic GABAB receptor agonist caused less reduction of neuronal and blood flow responses compared to the postsynaptic glutamate receptor antagonists. In conclusion, local hyperemia by synaptically-evoked inhibitory neurons was primarily driven by their postsynaptic activities, possibly through NMDA receptor-dependent calcium signaling that was not wholly dependent on nitric oxide.
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Affiliation(s)
| | - Bistra Iordanova
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15203, United States
| | - Alberto L Vazquez
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15203, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15203, United States
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon 440-330, Korea; Department of Biomedical Engineering, Sungkyunkwan University, Suwon, 440-330, Korea
| | - Mitsuhiro Fukuda
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15203, United States.
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13
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Bo B, Li Y, Li W, Wang Y, Tong S. Neurovascular Coupling Impairment in Acute Ischemic Stroke by Optogenetics and Optical Brain Imaging. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:3727-3730. [PMID: 33018811 DOI: 10.1109/embc44109.2020.9176641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The coupling between neuronal activity and cerebral blood flow (CBF), known as neurovascular coupling, has been reported to be impaired after stroke. This study aims to investigate the neurovascular coupling impairment at the acute stage after ischemic stroke. Laser speckle contrast imaging (LSCI) was applied to measure the hemodynamic response to optogenetic excitation of sensorimotor neurons in healthy and ischemic brain. The results showed that the hemodynamic response to optogenetic stimulation decreased and the regional CBF response was correlated with the distance from the ischemic core at the acute stage, regardless of the change in resting CBF. Our results also demonstrated that excitatory neuronal stimulation of intact area could promote the recovery of neurovascular coupling, whereas peri-infarct neuronal excitation failed to restore neurovascular function 24 hrs after ischemia. These results suggested the intact periphery of penumbra as the target for excitatory stimulation in aspect of restoring the perfusion after ischemic stroke.
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14
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Bo B, Li Y, Li W, Wang Y, Tong S. Cortical Hemodynamic Response to Multi-afferent Stimulation: an optical imaging study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:2913-2916. [PMID: 33018616 DOI: 10.1109/embc44109.2020.9175284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Multisensory stimulation plays an important role in the recovery of ischemic stroke. However, little is known about the interactions between neuronal activities with multi-afferent stimulations and their effects on hemodynamic responses. Optogenetics has been a useful tool in neuroscience research to unravel the mechanisms of neurovascular coupling at cell-specific level. In this study, we applied laser speckle contrast imaging (LSCI) to map the cortical hemodynamic response with high spatiotemporal resolution. The results showed that optogenetic inhibition of pyramidal neurons in sensorimotor cortex induced both local and distant increases of cerebral blood flow (CBF) with dual peaks, and the full width at half maximum (FWHM) was significantly larger than that of the CBF response to optogenetic excitation. Furthermore, optogenetic excitation of pyramidal neurons could significantly increase the local CBF response to sensory stimulation, whereas optogenetic inhibition of pyramidal neurons decreased the local CBF response at the early stage after sensory stimulation and increased the distant CBF response during the recovery period. Our work provided useful insights into the mechanisms of brain stimulation, which might help in clinical neurological applications.
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15
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Krawchuk MB, Ruff CF, Yang X, Ross SE, Vazquez AL. Optogenetic assessment of VIP, PV, SOM and NOS inhibitory neuron activity and cerebral blood flow regulation in mouse somato-sensory cortex. J Cereb Blood Flow Metab 2020; 40:1427-1440. [PMID: 31418628 PMCID: PMC7307010 DOI: 10.1177/0271678x19870105] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 12/31/2022]
Abstract
The impact of different neuronal populations on local cerebral blood flow (CBF) regulation is not well known and insight into these relationships could enhance the interpretation of brain function and dysfunction from brain imaging data. We investigated the role of sub-types of inhibitory neuron activity on the regulation of CBF using optogenetics, laser Doppler flowmetry and different transgenic mouse models (parvalbumin (PV), vasoactive intestinal peptide (VIP), somatostatin (SOM) and nitric oxide synthase (NOS)). Whisker stimulation was used to verify that typical CBF responses were obtained in all mice. Photo-stimulation of SOM-cre and NOS-cre mice produced significant increases in CBF that were similar to whisker responses. In NOS-cre mice, CBF responses scaled with the photo-stimulus pulse duration and frequency. In SOM-cre mice, CBF increases were followed by decreases. In VIP-cre mice, photo-stimulation did not consistently produce significant changes in CBF, while slower increases in CBF that peaked 14-18 s after stimulation onset were observed in PV-cre mice. Control experiments performed in non-expressing regions showed no changes in CBF. These findings suggest that dysfunction in NOS or SOM neurons can have a significant impact on vascular responses that are detected by brain imaging methods like functional magnetic resonance imaging (fMRI).
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Affiliation(s)
- Michael B Krawchuk
- Department of Neuroscience, University of
Pittsburgh, Pittsburgh, PA, USA
| | - Catherine F Ruff
- Department of Neurobiology, University of
Pittsburgh, Pittsburgh, PA, USA
| | - Xiaoling Yang
- Department of Radiology, University of
Pittsburgh, Pittsburgh, PA, USA
| | - Sarah E Ross
- Department of Neurobiology, University of
Pittsburgh, Pittsburgh, PA, USA
| | - Alberto L Vazquez
- Department of Radiology, University of
Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering University of
Pittsburgh, Pittsburgh, PA, USA
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16
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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
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17
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Böhm M, Chung DY, Gómez CA, Qin T, Takizawa T, Sadeghian H, Sugimoto K, Sakadžić S, Yaseen MA, Ayata C. Neurovascular coupling during optogenetic functional activation: Local and remote stimulus-response characteristics, and uncoupling by spreading depression. J Cereb Blood Flow Metab 2020; 40:808-822. [PMID: 31063009 PMCID: PMC7168797 DOI: 10.1177/0271678x19845934] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neurovascular coupling is a fundamental response that links activity to perfusion. Traditional paradigms of neurovascular coupling utilize somatosensory stimulation to activate the primary sensory cortex through subcortical relays. Therefore, examination of neurovascular coupling in disease models can be confounded if the disease process affects these multisynaptic pathways. Optogenetic stimulation is an alternative to directly activate neurons, bypassing the subcortical relays. We employed minimally invasive optogenetic cortical activation through intact skull in Thy1-channelrhodopsin-2 transgenic mice, examined the blood flow changes using laser speckle imaging, and related these to evoked electrophysiological activity. Our data show that optogenetic activation of barrel cortex triggers intensity- and frequency-dependent hyperemia both locally within the barrel cortex (>50% CBF increase), and remotely within the ipsilateral motor cortex (>30% CBF increase). Intriguingly, activation of the barrel cortex causes a small (∼10%) but reproducible hypoperfusion within the contralateral barrel cortex, electrophysiologically linked to transhemispheric inhibition. Cortical spreading depression, known to cause neurovascular uncoupling, diminishes optogenetic hyperemia by more than 50% for up to an hour despite rapid recovery of evoked electrophysiological activity, recapitulating a unique feature of physiological neurovascular coupling. Altogether, these data establish a minimally invasive paradigm to investigate neurovascular coupling for longitudinal characterization of cerebrovascular pathologies.
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Affiliation(s)
- Maximilian Böhm
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - David Y Chung
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Neurocritical Care and Emergency Neurology, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Carlos A Gómez
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Tao Qin
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Tsubasa Takizawa
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| | - Homa Sadeghian
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Kazutaka Sugimoto
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Japan
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Cenk Ayata
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Stroke Service, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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18
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Optogenetic translocation of protons out of penumbral neurons is protective in a rodent model of focal cerebral ischemia. Brain Stimul 2020; 13:881-890. [PMID: 32289721 DOI: 10.1016/j.brs.2020.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Intracellular acidosis in the ischemic penumbra can contribute to further cell death, effectively enlarging the infarct core. Restoring the acid-base balance may enhance tissue survivability after cerebral ischemia. OBJECTIVE This study investigated whether translocating protons out of penumbral neurons could mitigate tissue acidification and induce neuroprotection in a rodent model of acute cerebral ischemia. METHODS We modulated the penumbral neurons via a light-driven pump to translocate protons out (i.e., archaerhodopsin/ArchT group) or into (i.e., channelrhodopsin-2/ChR2 group) neurons after focal cerebral ischemia in rats. Intracellular pH values were imaged via neutral red (NR) fluorescence and cerebral blood flow (CBF) was monitored through laser speckle contrast imaging (LSCI). Global CBF responses to electrical stimulation of the hindlimbs were obtained 24 h and 48 h after ischemia to assess neurological function. Behavioral and histological outcomes were evaluated 48 h after ischemia. A control group without gene modification was included. RESULTS The reduction of relative pH (RpH), the amplitude of negative peak of hypoemic response (RNP) and the hemispheric lateralization index (LI) in ArchT group were significantly less than those of the ChR2 or control group. Moreover, RpH was strongly correlated with RNP (r = 0.60) and LI (r24h = 0.80, r48h = 0.59). In addition, behavioral and histological results supported a neuroprotective effect of countering neuronal acidosis in penumbra through optogenetic stimulation. CONCLUSION(S) These results indicate that countering intracellular acidosis by optogenetically translocating protons out of penumbral neurons during the acute ischemic stage could induce protection after ischemic brain injury.
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19
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Mandino F, Cerri DH, Garin CM, Straathof M, van Tilborg GAF, Chakravarty MM, Dhenain M, Dijkhuizen RM, Gozzi A, Hess A, Keilholz SD, Lerch JP, Shih YYI, Grandjean J. Animal Functional Magnetic Resonance Imaging: Trends and Path Toward Standardization. Front Neuroinform 2020; 13:78. [PMID: 32038217 PMCID: PMC6987455 DOI: 10.3389/fninf.2019.00078] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 12/19/2019] [Indexed: 12/21/2022] Open
Abstract
Animal whole-brain functional magnetic resonance imaging (fMRI) provides a non-invasive window into brain activity. A collection of associated methods aims to replicate observations made in humans and to identify the mechanisms underlying the distributed neuronal activity in the healthy and disordered brain. Animal fMRI studies have developed rapidly over the past years, fueled by the development of resting-state fMRI connectivity and genetically encoded neuromodulatory tools. Yet, comparisons between sites remain hampered by lack of standardization. Recently, we highlighted that mouse resting-state functional connectivity converges across centers, although large discrepancies in sensitivity and specificity remained. Here, we explore past and present trends within the animal fMRI community and highlight critical aspects in study design, data acquisition, and post-processing operations, that may affect the results and influence the comparability between studies. We also suggest practices aimed to promote the adoption of standards within the community and improve between-lab reproducibility. The implementation of standardized animal neuroimaging protocols will facilitate animal population imaging efforts as well as meta-analysis and replication studies, the gold standards in evidence-based science.
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Affiliation(s)
- Francesca Mandino
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Singapore
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Domenic H. Cerri
- Center for Animal MRI, Department of Neurology, Biomedical Research Imaging Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Clement M. Garin
- Direction de la Recherche Fondamentale, MIRCen, Institut de Biologie François Jacob, Commissariat à l’Énergie Atomique et aux Énergies Alternatives, Fontenay-aux-Roses, France
- Neurodegenerative Diseases Laboratory, Centre National de la Recherche Scientifique, UMR 9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Milou Straathof
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Geralda A. F. van Tilborg
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - M. Mallar Chakravarty
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
- Department of Biological and Biomedical Engineering, Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Marc Dhenain
- Direction de la Recherche Fondamentale, MIRCen, Institut de Biologie François Jacob, Commissariat à l’Énergie Atomique et aux Énergies Alternatives, Fontenay-aux-Roses, France
- Neurodegenerative Diseases Laboratory, Centre National de la Recherche Scientifique, UMR 9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Rick M. Dijkhuizen
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Alessandro Gozzi
- Functional Neuroimaging Laboratory, Istituto Italiano di Tecnologia, Centre for Neuroscience and Cognitive Systems @ UNITN, Rovereto, Italy
| | - Andreas Hess
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich–Alexander University Erlangen–Nürnberg, Erlangen, Germany
| | - Shella D. Keilholz
- Department of Biomedical Engineering, Georgia Tech, Emory University, Atlanta, GA, United States
| | - Jason P. Lerch
- Hospital for Sick Children, Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Wellcome Centre for Integrative NeuroImaging, University of Oxford, Oxford, United Kingdom
| | - Yen-Yu Ian Shih
- Center for Animal MRI, Department of Neurology, Biomedical Research Imaging Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Joanes Grandjean
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Singapore
- Department of Radiology and Nuclear Medicine, Donders Institute for Brain, Cognition, and Behaviour, Donders Institute, Radboud University Medical Center, Nijmegen, Netherlands
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20
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Neurovascular Coupling under Chronic Stress Is Modified by Altered GABAergic Interneuron Activity. J Neurosci 2019; 39:10081-10095. [PMID: 31672788 PMCID: PMC6978951 DOI: 10.1523/jneurosci.1357-19.2019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/10/2019] [Accepted: 10/15/2019] [Indexed: 12/15/2022] Open
Abstract
Neurovascular coupling (NVC), the interaction between neural activity and vascular response, ensures normal brain function by maintaining brain homeostasis. We previously reported altered cerebrovascular responses during functional hyperemia in chronically stressed animals. However, the underlying neuronal-level changes associated with those hemodynamic changes remained unclear. Here, using in vivo and ex vivo experiments, we investigate the neuronal origins of altered NVC dynamics under chronic stress conditions in adult male mice. Stimulus-evoked hemodynamic and neural responses, especially beta and gamma-band local field potential activity, were significantly lower in chronically stressed animals, and the NVC relationship, itself, had changed. Further, using acute brain slices, we discovered that the underlying cause of this change was dysfunction of neuronal nitric oxide synthase (nNOS)-mediated vascular responses. Using FISH to check the mRNA expression of several GABAergic subtypes, we confirmed that only nNOS mRNA was significantly decreased in chronically stressed mice. Ultimately, chronic stress impairs NVC by diminishing nNOS-mediated vasodilation responses to local neural activity. Overall, these findings provide useful information in understanding NVC dynamics in the healthy brain. More importantly, this study reveals that impaired nNOS-mediated NVC function may be a contributory factor in the progression of stress-related diseases. SIGNIFICANCE STATEMENT The correlation between neuronal activity and cerebral vascular dynamics is defined as neurovascular coupling (NVC), which plays an important role for meeting the metabolic demands of the brain. However, the impact of chronic stress, which is a contributory factor of many cerebrovascular diseases, on NVC is poorly understood. We therefore investigated the effects of chronic stress on impaired neurovascular response to sensory stimulation and their underlying mechanisms. Multimodal approaches, from in vivo hemodynamic imaging and electrophysiology to ex vivo vascular imaging with pharmacological treatment, patch-clamp recording, FISH, and immunohistochemistry revealed that chronic stress-induced dysfunction of nNOS-expressing interneurons contributes to NVC impairment. These findings will provide useful information to understand the role of nNOS interneurons in NVC in normal and pathological conditions.
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21
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Albers F, Wachsmuth L, Schache D, Lambers H, Faber C. Functional MRI Readouts From BOLD and Diffusion Measurements Differentially Respond to Optogenetic Activation and Tissue Heating. Front Neurosci 2019; 13:1104. [PMID: 31708721 PMCID: PMC6821691 DOI: 10.3389/fnins.2019.01104] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 10/01/2019] [Indexed: 12/12/2022] Open
Abstract
Functional blood-oxygenation-level-dependent (BOLD) MRI provides a brain-wide readout that depends on the hemodynamic response to neuronal activity. Diffusion fMRI has been proposed as an alternative to BOLD fMRI and has been postulated to directly rely on neuronal activity. These complementary functional readouts are versatile tools to be combined with optogenetic stimulation to investigate networks of the brain. The cell-specificity and temporal precision of optogenetic manipulations promise to enable further investigation of the origin of fMRI signals. The signal characteristics of the diffusion fMRI readout vice versa may better resolve network effects of optogenetic stimulation. However, the light application needed for optogenetic stimulation is accompanied by heat deposition within the tissue. As both diffusion and BOLD are sensitive to temperature changes, light application can lead to apparent activations confounding the interpretation of fMRI data. The degree of tissue heating, the appearance of apparent activation in different fMRI sequences and the origin of these phenomena are not well understood. Here, we disentangled apparent activations in BOLD and diffusion measurements in rats from physiological activation upon sensory or optogenetic stimulation. Both, BOLD and diffusion fMRI revealed similar signal shapes upon sensory stimulation that differed clearly from those upon heating. Apparent activations induced by high-intensity light application were dominated by T2∗-effects and resulted in mainly negative signal changes. We estimated that even low-intensity light application used for optogenetic stimulation reduces the BOLD response close to the fiber by up to 0.4%. The diffusion fMRI signal contained T2, T2∗ and diffusion components. The apparent diffusion coefficient, which reflects the isolated diffusion component, showed negative changes upon both optogenetic and electric forepaw stimulation. In contrast, positive changes were detected upon high-intensity light application and thus ruled out heating as a major contributor to the diffusion fMRI signal.
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Affiliation(s)
- Franziska Albers
- Translational Research Imaging Center, Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Lydia Wachsmuth
- Translational Research Imaging Center, Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Daniel Schache
- Translational Research Imaging Center, Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Henriette Lambers
- Translational Research Imaging Center, Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Cornelius Faber
- Translational Research Imaging Center, Department of Clinical Radiology, University Hospital Münster, Münster, Germany
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22
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Drew PJ. Vascular and neural basis of the BOLD signal. Curr Opin Neurobiol 2019; 58:61-69. [PMID: 31336326 DOI: 10.1016/j.conb.2019.06.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 06/22/2019] [Indexed: 12/26/2022]
Abstract
Neural activity in the brain is usually coupled to increases in local cerebral blood flow, leading to the increase in oxygenation that generates the BOLD fMRI signal. Recent work has begun to elucidate the vascular and neural mechanisms underlying the BOLD signal. The dilatory response is distributed throughout the vascular network. Arteries actively dilate within a second following neural activity increases, while venous distensions are passive and have a time course that last tens of seconds. Vasodilation, and thus local blood flow, is controlled by the activity of both neurons and astrocytes via multiple different pathways. The relationship between sensory-driven neural activity and the vascular dynamics in sensory areas are well-captured with a linear convolution model. However, depending on the behavioral state or brain region, the coupling between neural activity and hemodynamic signals can be weak or even inverted.
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Affiliation(s)
- Patrick J Drew
- Departments of Engineering Science and Mechanics, Biomedical Engineering and Neurosurgery, Pennsylvania State University, University Park, PA 16802, United States.
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23
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Li B, Esipova TV, Sencan I, Kılıç K, Fu B, Desjardins M, Moeini M, Kura S, Yaseen MA, Lesage F, Østergaard L, Devor A, Boas DA, Vinogradov SA, Sakadžić S. More homogeneous capillary flow and oxygenation in deeper cortical layers correlate with increased oxygen extraction. eLife 2019; 8:42299. [PMID: 31305237 PMCID: PMC6636997 DOI: 10.7554/elife.42299] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 07/01/2019] [Indexed: 01/01/2023] Open
Abstract
Our understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of resting-state microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that more homogeneous distribution of the physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to local brain metabolism. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of the diseases that affect cerebral microcirculation.
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Affiliation(s)
- Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Tatiana V Esipova
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, United States.,Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Ikbal Sencan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Kıvılcım Kılıç
- Department of Neurosciences, University of California, San Diego, La Jolla, United States
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Michele Desjardins
- Department of Radiology, University of California, San Diego, La Jolla, United States
| | - Mohammad Moeini
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.,Research Centre, Montreal Heart Institute, Montréal, Canada
| | - Sreekanth Kura
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Frederic Lesage
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.,Research Centre, Montreal Heart Institute, Montréal, Canada
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States.,Department of Neurosciences, University of California, San Diego, La Jolla, United States.,Department of Radiology, University of California, San Diego, La Jolla, United States
| | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States.,Department of Biomedical Engineering, Boston University, Boston, United States
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, United States.,Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
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24
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Snyder AZ, Bauer AQ. Mapping Structure-Function Relationships in the Brain. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:510-521. [PMID: 30528965 PMCID: PMC6488459 DOI: 10.1016/j.bpsc.2018.10.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/17/2018] [Accepted: 10/17/2018] [Indexed: 01/06/2023]
Abstract
Mapping the structural and functional connectivity of the brain is a major focus of systems neuroscience research and will help to identify causally important changes in neural circuitry responsible for behavioral dysfunction. Several methods for examining brain activity in humans have been extended to rodent and monkey models in which molecular and genetic manipulations exist for linking to human disease. In this review, which is part of a special issue focused on bridging brain connectivity information across species and spatiotemporal scales, we address mapping brain activity and neural connectivity in rodents using optogenetics in conjunction with either functional magnetic resonance imaging or optical intrinsic signal imaging. We chose to focus on these techniques because they are capable of reporting spontaneous or evoked hemodynamic activity most closely linked to human neuroimaging studies. We discuss the capabilities and limitations of blood-based imaging methods, usage of optogenetic techniques to map neural systems in rodent models, and other powerful mapping techniques for examining neural connectivity over different spatial and temporal scales. We also discuss implementing strategies for mapping brain connectivity in humans with both basic and clinical applications, and conclude with how cross-species mapping studies can be utilized to influence preclinical imaging studies and clinical practices alike.
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Affiliation(s)
- Abraham Z Snyder
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Adam Q Bauer
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri.
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25
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In vivo neurovascular response to focused photoactivation of Channelrhodopsin-2. Neuroimage 2019; 192:135-144. [DOI: 10.1016/j.neuroimage.2019.01.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/31/2018] [Accepted: 01/14/2019] [Indexed: 01/03/2023] Open
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26
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Albers F, Wachsmuth L, van Alst TM, Faber C. Multimodal Functional Neuroimaging by Simultaneous BOLD fMRI and Fiber-Optic Calcium Recordings and Optogenetic Control. Mol Imaging Biol 2019; 20:171-182. [PMID: 29027094 DOI: 10.1007/s11307-017-1130-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Recent developments of optogenetic tools and fluorescence-based calcium recording techniques enable the manipulation and monitoring of neural circuits on a cellular level. Non-invasive imaging of brain networks, however, requires the application of methods such as blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI), which is commonly used for functional neuroimaging. While BOLD fMRI provides brain-wide non-invasive reading of the hemodynamic response, it is only an indirect measure of neural activity. Direct observation of neural responses requires electrophysiological or optical methods. The latter can be combined with optogenetic control of neuronal circuits and are MRI compatible. Yet, simultaneous optical recordings are still limited to fiber-optic-based approaches. Here, we review the integration of optical recordings and optogenetic manipulation into fMRI experiments. As a practical example, we describe how BOLD fMRI in a 9.4-T small animal MR scanner can be combined with in vivo fiber-optic calcium recordings and optogenetic control in a multimodal setup. We present simultaneous BOLD fMRI and calcium recordings under optogenetic control in rat. We outline details about MR coil configuration, choice, and usage of opsins and chemically and genetically encoded calcium sensors, fiber implantation, appropriate light power for stimulation, and calcium signal detection, to provide a glimpse into challenges and opportunities of this multimodal molecular neuroimaging approach.
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Affiliation(s)
- Franziska Albers
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Lydia Wachsmuth
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | | | - Cornelius Faber
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany.
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27
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Masamoto K, Vazquez A. Optical imaging and modulation of neurovascular responses. J Cereb Blood Flow Metab 2018; 38:2057-2072. [PMID: 30334644 PMCID: PMC6282226 DOI: 10.1177/0271678x18803372] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 09/02/2018] [Indexed: 12/17/2022]
Abstract
The cerebral microvasculature consists of pial vascular networks, parenchymal descending arterioles, ascending venules and parenchymal capillaries. This vascular compartmentalization is vital to precisely deliver blood to balance continuously varying neural demands in multiple brain regions. Optical imaging techniques have facilitated the investigation of dynamic spatial and temporal properties of microvascular functions in real time. Their combination with transgenic animal models encoding specific genetic targets have further strengthened the importance of optical methods for neurovascular research by allowing for the modulation and monitoring of neuro vascular function. Image analysis methods with three-dimensional reconstruction are also helping to understand the complexity of microscopic observations. Here, we review the compartmentalized cerebral microvascular responses to global perturbations as well as regional changes in response to neural activity to highlight the differences in vascular action sites. In addition, microvascular responses elicited by optical modulation of different cell-type targets are summarized with emphasis on variable spatiotemporal dynamics of microvascular responses. Finally, long-term changes in microvascular compartmentalization are discussed to help understand potential relationships between CBF disturbances and the development of neurodegenerative diseases and cognitive decline.
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Affiliation(s)
- Kazuto Masamoto
- Faculty of Informatics and Engineering, University of Electro-Communications, Tokyo, Japan
- Brain Science Inspired Life Support Research Center, University of Electro-Communications, Tokyo, Japan
| | - Alberto Vazquez
- Departments of Radiology and Bioengineering, University of Pittsburgh, PA, USA
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28
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Atry F, Chen RCH, Pisaniello J, Brodnick S, Suminski AJ, Novello J, Ness J, Williams JC, Pashaie R. Optogenetic interrogation of neurovascular coupling in the cerebral cortex of transgenic mice. J Neural Eng 2018; 15:056033. [DOI: 10.1088/1741-2552/aad840] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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29
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Bauer AQ, Kraft AW, Baxter GA, Wright PW, Reisman MD, Bice AR, Park JJ, Bruchas MR, Snyder AZ, Lee JM, Culver JP. Effective Connectivity Measured Using Optogenetically Evoked Hemodynamic Signals Exhibits Topography Distinct from Resting State Functional Connectivity in the Mouse. Cereb Cortex 2018; 28:370-386. [PMID: 29136125 PMCID: PMC6057523 DOI: 10.1093/cercor/bhx298] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Indexed: 02/07/2023] Open
Abstract
Brain connectomics has expanded from histological assessment of axonal projection connectivity (APC) to encompass resting state functional connectivity (RS-FC). RS-FC analyses are efficient for whole-brain mapping, but attempts to explain aspects of RS-FC (e.g., interhemispheric RS-FC) based on APC have been only partially successful. Neuroimaging with hemoglobin alone lacks specificity for determining how activity in a population of cells contributes to RS-FC. Wide-field mapping of optogenetically defined connectivity could provide insights into the brain's structure-function relationship. We combined optogenetics with optical intrinsic signal imaging to create an efficient, optogenetic effective connectivity (Opto-EC) mapping assay. We examined EC patterns of excitatory neurons in awake, Thy1-ChR2 transgenic mice. These Thy1-based EC (Thy1-EC) patterns were evaluated against RS-FC over the cortex. Compared to RS-FC, Thy1-EC exhibited increased spatial specificity, reduced interhemispheric connectivity in regions with strong RS-FC, and appreciable connection strength asymmetry. Comparing the topography of Thy1-EC and RS-FC patterns to maps of APC revealed that Thy1-EC more closely resembled APC than did RS-FC. The more general method of Opto-EC mapping with hemoglobin can be determined for 100 sites in single animals in under an hour, and is amenable to other neuroimaging modalities. Opto-EC mapping represents a powerful strategy for examining evolving connectivity-related circuit plasticity.
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Affiliation(s)
- Adam Q Bauer
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Andrew W Kraft
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Grant A Baxter
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Patrick W Wright
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Matthew D Reisman
- Department of Physics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Annie R Bice
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Jasmine J Park
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Michael R Bruchas
- Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Abraham Z Snyder
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Jin-Moo Lee
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Neurology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Joseph P Culver
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Physics, Washington University School of Medicine, Saint Louis, MO 63110, USA
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30
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Eles JR, Vazquez AL, Kozai TDY, Cui XT. In vivo imaging of neuronal calcium during electrode implantation: Spatial and temporal mapping of damage and recovery. Biomaterials 2018; 174:79-94. [PMID: 29783119 PMCID: PMC5987772 DOI: 10.1016/j.biomaterials.2018.04.043] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/16/2018] [Accepted: 04/21/2018] [Indexed: 12/13/2022]
Abstract
Implantable electrode devices enable long-term electrophysiological recordings for brain-machine interfaces and basic neuroscience research. Implantation of these devices, however, leads to neuronal damage and progressive neural degeneration that can lead to device failure. The present study uses in vivo two-photon microscopy to study the calcium activity and morphology of neurons before, during, and one month after electrode implantation to determine how implantation trauma injures neurons. We show that implantation leads to prolonged, elevated calcium levels in neurons within 150 μm of the electrode interface. These neurons show signs of mechanical distortion and mechanoporation after implantation, suggesting that calcium influx is related to mechanical trauma. Further, calcium-laden neurites develop signs of axonal injury at 1-3 h post-insert. Over the first month after implantation, physiological neuronal calcium activity increases, suggesting that neurons may be recovering. By defining the mechanisms of neuron damage after electrode implantation, our results suggest new directions for therapies to improve electrode longevity.
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Affiliation(s)
- James R Eles
- Bioengineering, University of Pittsburgh, United States; Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, United States
| | - Alberto L Vazquez
- Bioengineering, University of Pittsburgh, United States; Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, United States; Radiology, University of Pittsburgh, United States
| | - Takashi D Y Kozai
- Bioengineering, University of Pittsburgh, United States; Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, United States; McGowan Institute for Regenerative Medicine, University of Pittsburgh, United States; NeuroTech Center of the University of Pittsburgh Brain Institute, United States; Center for Neuroscience, University of Pittsburgh, United States
| | - X Tracy Cui
- Bioengineering, University of Pittsburgh, United States; Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, United States; McGowan Institute for Regenerative Medicine, University of Pittsburgh, United States.
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31
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Kim SG. Biophysics of BOLD fMRI investigated with animal models. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 292:82-89. [PMID: 29705033 DOI: 10.1016/j.jmr.2018.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 02/14/2018] [Accepted: 04/09/2018] [Indexed: 06/08/2023]
Abstract
The widely-used BOLD fMRI signal depends on various anatomical, physiological, and imaging parameters. Thus, it is important to examine its biophysical and physiological source in order to optimize, model and accurately interpret fMRI. Animal models have been used to investigate these issues to take systematic measurements and combine with conventional invasive approaches. Here, we reviewed and discussed multiple issues, including the echo time-dependent intravascular contribution and extravascular contributions, gradient-echo vs. spin-echo fMRI, the physiological source of BOLD fMRI, arterial vs. venous cerebral blood volume change, cerebral oxygen consumption change, and arterial oxygen saturation change. We then discuss future directions of animal fMRI and translation to human fMRI. Systematic biophysical BOLD fMRI studies provide insight into the modeling and interpretation of BOLD fMRI in animals and humans.
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Affiliation(s)
- Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Republic of Korea; Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
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32
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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: 27] [Impact Index Per Article: 4.5] [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.
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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
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33
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Albers F, Schmid F, Wachsmuth L, Faber C. Line scanning fMRI reveals earlier onset of optogenetically evoked BOLD response in rat somatosensory cortex as compared to sensory stimulation. Neuroimage 2018; 164:144-154. [DOI: 10.1016/j.neuroimage.2016.12.059] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/17/2016] [Accepted: 12/20/2016] [Indexed: 12/20/2022] Open
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34
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Bo B, Li W, Wang Y, Li Y, Tong S. Hemodynamic response to optogenetic stimulation varied under different stimulus parameters. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:4022-4025. [PMID: 29060779 DOI: 10.1109/embc.2017.8037738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The coupling between neuronal activity and cerebral blood flow(CBF), known as neurovascular coupling, serves as the basis of functional brain imaging. Optogenetics provides a precise and selective approach to manipulate the activity in cell-specific neurons. It has been used in neuroscience research for comprehensive understanding about the light-evoked neurovascular coupling in rodent neuronal circuits. However, the spatiotemporal CBF response characteristics under different stimulus parameters such as pulse width and frequency remains unclear due to the lack of efficient CBF imaging technology. In this work, we used laser speckle contrast imaging(LSCI) to study the spatiotemporal hemodynamic response to optogenetic stimulation with different pulse widths (5ms, 10ms, 20ms) and frequencies (5Hz, 10Hz, 20Hz) in Channelrhodopsin-2(ChR2) expressing rats. The results showed that the averaged CBF response generally increased along with higher pulse width or frequency. The CBF peak response was significantly higher at 20ms and it took significantly shorter time to reach response peak at 5Hz. Our work adds additional insights in understanding the cell-specific neurovascular coupling mechanism and provides informative reference when applying ChR2 optogenetics in neurological disease research.
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35
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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.
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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
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36
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Poplawsky AJ, Fukuda M, Kim SG. Foundations of layer-specific fMRI and investigations of neurophysiological activity in the laminarized neocortex and olfactory bulb of animal models. Neuroimage 2017; 199:718-729. [PMID: 28502845 DOI: 10.1016/j.neuroimage.2017.05.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 05/02/2017] [Accepted: 05/11/2017] [Indexed: 12/25/2022] Open
Abstract
Laminar organization of neuronal circuits is a recurring feature of how the brain processes information. For instance, different layers compartmentalize different cell types, synaptic activities, and have unique intrinsic and extrinsic connections that serve as units for specialized signal processing. Functional MRI is an invaluable tool to investigate laminar processing in the in vivo human brain, but it measures neuronal activity indirectly by way of the hemodynamic response. Therefore, the accuracy of high-resolution laminar fMRI depends on how precisely it can measure localized microvascular changes nearest to the site of evoked activity. To determine the specificity of fMRI responses to the true neurophysiological responses across layers, the flexibility to invasive procedures in animal models has been necessary. In this review, we will examine different fMRI contrasts and their appropriate uses for layer-specific fMRI, and how localized laminar processing was examined in the neocortex and olfactory bulb. Through collective efforts, it was determined that microvessels, including capillaries, are regulated within single layers and that several endogenous and contrast-enhanced fMRI contrast mechanisms can separate these neural-specific vascular changes from the nonspecific, especially cerebral blood volume-weighted fMRI with intravenous contrast agent injection. We will also propose some open questions that are relevant for the successful implementation of layer-specific fMRI and its potential future directions to study laminar processing when combined with optogenetics.
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Affiliation(s)
- Alexander John Poplawsky
- Neuroimaging Laboratory, Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Mitsuhiro Fukuda
- Neuroimaging Laboratory, Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute of Basic Science, Suwon 440-746, Republic of Korea; Department of Biomedical Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea
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37
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Grinband J, Steffener J, Razlighi QR, Stern Y. BOLD neurovascular coupling does not change significantly with normal aging. Hum Brain Mapp 2017; 38:3538-3551. [PMID: 28419680 DOI: 10.1002/hbm.23608] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 03/28/2017] [Accepted: 03/28/2017] [Indexed: 12/11/2022] Open
Abstract
Studies of cognitive function that compare the blood oxygenation level dependent (BOLD) signal across age groups often require the assumption that neurovascular coupling does not change with age. Tests of this assumption have produced mixed results regarding the strength of the coupling and its relative time course. Using deconvolution, we found that age does not have a significant effect on the time course of the hemodynamic impulse response function or on the slope of the BOLD versus stimulus duration relationship. These results suggest that in cognitive studies of healthy aging, group differences in BOLD activation are likely due to age-related changes in cognitive-neural interactions and information processing rather than to impairments in neurovascular coupling. Hum Brain Mapp 38:3538-3551, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Jack Grinband
- Department of Radiology, Columbia University, New York
| | - Jason Steffener
- Interdisciplinary School of Health Sciences, University of Ottawa, Ontario
| | - Qolamreza R Razlighi
- Department of Neurology, Columbia University, New York.,Department of Biomedical Engineering, Columbia University, New York
| | - Yaakov Stern
- Department of Neurology, Columbia University, New York
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Unexpected global impact of VTA dopamine neuron activation as measured by opto-fMRI. Mol Psychiatry 2017; 22:585-594. [PMID: 27457809 PMCID: PMC5269559 DOI: 10.1038/mp.2016.102] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 04/27/2016] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
Dopamine neurons in the ventral tegmental area (VTA) are strongly implicated in cognitive and affective processing as well as in psychiatric disorders, including schizophrenia, depression, attention-deficit hyperactivity disorder and substance abuse disorders. In human studies, dopamine-related functions are routinely assessed using functional magnetic resonance imaging (fMRI) measures of blood oxygenation-level-dependent (BOLD) signals during the performance of dopamine-dependent tasks. There is, however, a critical void in our knowledge about whether and how activation of VTA dopamine neurons specifically influences regional or global fMRI signals. Here, we used optogenetics in Th::Cre rats to selectively stimulate VTA dopamine neurons while simultaneously measuring global hemodynamic changes using BOLD and cerebral blood volume-weighted (CBVw) fMRI. Phasic activation of VTA dopamine neurons increased BOLD and CBVw fMRI signals in VTA-innervated limbic regions, including the ventral striatum (nucleus accumbens). Surprisingly, basal ganglia regions that receive sparse or no VTA dopaminergic innervation, including the dorsal striatum and the globus pallidus, were also activated. In fact, the most prominent fMRI signal increase in the forebrain was observed in the dorsal striatum that is not traditionally associated with VTA dopamine neurotransmission. These data establish causation between phasic activation of VTA dopamine neurons and global fMRI signals. They further suggest that mesolimbic and non-limbic basal ganglia dopamine circuits are functionally connected and thus provide a potential novel framework for understanding dopamine-dependent functions and interpreting data obtained from human fMRI studies.
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Volumetric Spatial Correlations of Neurovascular Coupling Studied using Single Pulse Opto-fMRI. Sci Rep 2017; 7:41583. [PMID: 28176823 PMCID: PMC5296864 DOI: 10.1038/srep41583] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 12/21/2016] [Indexed: 11/21/2022] Open
Abstract
Neurovascular coupling describes the link between neuronal activity and cerebral blood flow. This relationship has been the subject of intense scrutiny, with most previous work seeking to understand temporal correlations that describe neurovascular coupling. However, to date, the study of spatial correlations has been limited to two-dimensional mapping of neuronal or vascular derived signals emanating from the brain’s surface, using optical imaging techniques. Here, we investigate spatial correlations of neurovascular coupling in three dimensions, by applying a single 10 ms pulse of light to trigger optogenetic activation of cortical neurons transduced to express channelrhodopsin2, with concurrent fMRI. We estimated the spatial extent of increased neuronal activity using a model that takes into the account the scattering and absorption of blue light in brain tissue together with the relative density of channelrhodopsin2 expression across cortical layers. This method allows precise modulation of the volume of activated tissue in the cerebral cortex with concurrent three-dimensional mapping of functional hyperemia. Single pulse opto-fMRI minimizes adaptation, avoids heating artefacts and enables confined recruitment of the neuronal activity. Using this novel method, we present evidence for direct proportionality of volumetric spatial neurovascular coupling in the cerebral cortex.
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Riemann S, Helbing C, Angenstein F. From unspecific to adjusted, how the BOLD response in the rat hippocampus develops during consecutive stimulations. J Cereb Blood Flow Metab 2017; 37:590-604. [PMID: 26911895 PMCID: PMC5381453 DOI: 10.1177/0271678x16634715] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To determine the possibility to deconvolve measured BOLD responses to neuronal signals, the rat perforant pathway was electrically stimulated with 10 related stimulation protocols. All stimulation protocols were composed of low-frequency pulse sequences with superimposed high-frequency pulse bursts. Because high-frequency pulse bursts trigger only one synchronized spiking of granular cells, variations of the stimulation protocol were used: (a) to keep the spiking activity similar during the presentation of different numbers of pulses, (b) to apply identical numbers of pulses to induce different amounts of spiking activity, and (c) to concurrently vary the number of applied electrical pulses and resultant spiking activity. When complex pulse sequences enter the hippocampus, an unspecific default-like BOLD response is first generated, which relates neither to the number of incoming pulses nor to the induced spiking activity. Only during subsequent stimulations does the initial unspecific response adjust to a more adequate response, which in turn either strongly related to spiking activity when low-frequency pulses were applied or depended on the incoming activity when high-frequency pulse bursts were presented. Thus, only the development of BOLD responses during repetitive stimulations can predict the underlying neuronal activity and deconvolution analysis should not be performed during an initial stimulation period.
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Affiliation(s)
- Stephanie Riemann
- 1 Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Cornelia Helbing
- 1 Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Frank Angenstein
- 1 Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany.,2 Special Lab for Noninvasive Brain Imaging, Leibniz Institute for Neurobiology, Magdeburg, Germany
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Rungta RL, Osmanski BF, Boido D, Tanter M, Charpak S. Light controls cerebral blood flow in naive animals. Nat Commun 2017; 8:14191. [PMID: 28139643 PMCID: PMC5290324 DOI: 10.1038/ncomms14191] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 12/07/2016] [Indexed: 01/05/2023] Open
Abstract
Optogenetics is increasingly used to map brain activation using techniques that rely on functional hyperaemia, such as opto-fMRI. Here we test whether light stimulation protocols similar to those commonly used in opto-fMRI or to study neurovascular coupling modulate blood flow in mice that do not express light sensitive proteins. Combining two-photon laser scanning microscopy and ultrafast functional ultrasound imaging, we report that in the naive mouse brain, light per se causes a calcium decrease in arteriolar smooth muscle cells, leading to pronounced vasodilation, without excitation of neurons and astrocytes. This photodilation is reversible, reproducible and energy-dependent, appearing at about 0.5 mJ. These results impose careful consideration on the use of photo-activation in studies involving blood flow regulation, as well as in studies requiring prolonged and repetitive stimulations to correct cellular defects in pathological models. They also suggest that light could be used to locally increase blood flow in a controlled fashion. Combination of optogenetics and BOLD fMRI is routinely used to map neuronal activity upon photostimulation. Here the authors show that light, shone at intensities used in optogenetic studies, dilates vessels and increases blood flow independently of exogenous light-sensitive proteins in the mouse brain.
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Affiliation(s)
- Ravi L Rungta
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Bruno-Félix Osmanski
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Davide Boido
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Mickael Tanter
- Institut Langevin, Espci Paris, CNRS UMR 7587, INSERM U979, PSL Research University, 17 rue Moreau, Paris 75012, France
| | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
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Tang Q, Lin J, Tsytsarev V, Erzurumlu RS, Liu Y, Chen Y. Review of mesoscopic optical tomography for depth-resolved imaging of hemodynamic changes and neural activities. NEUROPHOTONICS 2017; 4:011009. [PMID: 27990452 PMCID: PMC5108095 DOI: 10.1117/1.nph.4.1.011009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 10/19/2016] [Indexed: 05/18/2023]
Abstract
Understanding the functional wiring of neural circuits and their patterns of activation following sensory stimulations is a fundamental task in the field of neuroscience. Furthermore, charting the activity patterns is undoubtedly important to elucidate how neural networks operate in the living brain. However, optical imaging must overcome the effects of light scattering in the tissue, which limit the light penetration depth and affect both the imaging quantitation and sensitivity. Laminar optical tomography (LOT) is a three-dimensional (3-D) in-vivo optical imaging technique that can be used for functional imaging. LOT can achieve both a resolution of 100 to [Formula: see text] and a penetration depth of 2 to 3 mm based either on absorption or fluorescence contrast, as well as large field-of-view and high acquisition speed. These advantages make LOT suitable for 3-D depth-resolved functional imaging of the neural functions in the brain and spinal cords. We review the basic principles and instrumentations of representative LOT systems, followed by recent applications of LOT on 3-D imaging of neural activities in the rat forepaw stimulation model and mouse whisker-barrel system.
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Affiliation(s)
- Qinggong Tang
- University of Maryland, Fischell Department of Bioengineering, 2334 Jeong H. Kim Engineering Building, College Park, Maryland 20742, United States
| | - Jonathan Lin
- University of Maryland, Fischell Department of Bioengineering, 2334 Jeong H. Kim Engineering Building, College Park, Maryland 20742, United States
| | - Vassiliy Tsytsarev
- University of Maryland School of Medicine, Department of Anatomy and Neurobiology, 20 Penn Street, HSFII S251, Baltimore, Maryland 21201, United States
| | - Reha S. Erzurumlu
- University of Maryland School of Medicine, Department of Anatomy and Neurobiology, 20 Penn Street, HSFII S251, Baltimore, Maryland 21201, United States
| | - Yi Liu
- University of Maryland, Fischell Department of Bioengineering, 2334 Jeong H. Kim Engineering Building, College Park, Maryland 20742, United States
| | - Yu Chen
- University of Maryland, Fischell Department of Bioengineering, 2334 Jeong H. Kim Engineering Building, College Park, Maryland 20742, United States
- Address all correspondence to: Yu Chen, E-mail:
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43
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Schmid F, Wachsmuth L, Schwalm M, Prouvot PH, Jubal ER, Fois C, Pramanik G, Zimmer C, Faber C, Stroh A. Assessing sensory versus optogenetic network activation by combining (o)fMRI with optical Ca2+ recordings. J Cereb Blood Flow Metab 2016; 36:1885-1900. [PMID: 26661247 PMCID: PMC5094300 DOI: 10.1177/0271678x15619428] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/03/2015] [Indexed: 11/16/2022]
Abstract
Encoding of sensory inputs in the cortex is characterized by sparse neuronal network activation. Optogenetic stimulation has previously been combined with fMRI (ofMRI) to probe functional networks. However, for a quantitative optogenetic probing of sensory-driven sparse network activation, the level of similarity between sensory and optogenetic network activation needs to be explored. Here, we complement ofMRI with optic fiber-based population Ca2+ recordings for a region-specific readout of neuronal spiking activity in rat brain. Comparing Ca2+ responses to the blood oxygenation level-dependent signal upon sensory stimulation with increasing frequencies showed adaptation of Ca2+ transients contrasted by an increase of blood oxygenation level-dependent responses, indicating that the optical recordings convey complementary information on neuronal network activity to the corresponding hemodynamic response. To study the similarity of optogenetic and sensory activation, we quantified the density of cells expressing channelrhodopsin-2 and modeled light propagation in the tissue. We estimated the effectively illuminated volume and numbers of optogenetically stimulated neurons, being indicative of sparse activation. At the functional level, upon either sensory or optogenetic stimulation we detected single-peak short-latency primary Ca2+ responses with similar amplitudes and found that blood oxygenation level-dependent responses showed similar time courses. These data suggest that ofMRI can serve as a representative model for functional brain mapping.
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Affiliation(s)
- Florian Schmid
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Lydia Wachsmuth
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Miriam Schwalm
- Focus Program translational Neuroscience & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Pierre-Hugues Prouvot
- Focus Program translational Neuroscience & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Eduardo Rosales Jubal
- Focus Program translational Neuroscience & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany.,Faculty of Psychology, Diego Portales University, Santiago, Chile
| | - Consuelo Fois
- Focus Program translational Neuroscience & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Gautam Pramanik
- Focus Program translational Neuroscience & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Claus Zimmer
- Department of Neuroradiology, Technical University Munich, Munich, Germany
| | - Cornelius Faber
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Albrecht Stroh
- Focus Program translational Neuroscience & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany
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44
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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: 77] [Impact Index Per Article: 9.6] [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'.
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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
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45
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Aksenov DP, Li L, Miller MJ, Wyrwicz AM. Blood oxygenation level dependent signal and neuronal adaptation to optogenetic and sensory stimulation in somatosensory cortex in awake animals. Eur J Neurosci 2016; 44:2722-2729. [PMID: 27564781 DOI: 10.1111/ejn.13384] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 08/18/2016] [Accepted: 08/23/2016] [Indexed: 11/27/2022]
Abstract
The adaptation of neuronal responses to stimulation, in which a peak transient response is followed by a sustained plateau, has been well-studied. The blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal has also been shown to exhibit adaptation on a longer time scale. However, some regions such as the visual and auditory cortices exhibit significant BOLD adaptation, whereas other such as the whisker barrel cortex may not adapt. In the sensory cortex a combination of thalamic inputs and intracortical activity drives hemodynamic changes, although the relative contributions of these components are not entirely understood. The aim of this study is to assess the role of thalamic inputs vs. intracortical processing in shaping BOLD adaptation during stimulation in the somatosensory cortex. Using simultaneous fMRI and electrophysiology in awake rabbits, we measured BOLD, local field potentials (LFPs), single- and multi-unit activity in the cortex during whisker and optogenetic stimulation. This design allowed us to compare BOLD and haemodynamic responses during activation of the normal thalamocortical sensory pathway (i.e., both inputs and intracortical activity) vs. the direct optical activation of intracortical circuitry alone. Our findings show that whereas LFP and multi-unit (MUA) responses adapted, neither optogenetic nor sensory stimulation produced significant BOLD adaptation. We observed for both paradigms a variety of excitatory and inhibitory single unit responses. We conclude that sensory feed-forward thalamic inputs are not primarily responsible for shaping BOLD adaptation to stimuli; but the single-unit results point to a role in this behaviour for specific excitatory and inhibitory neuronal sub-populations, which may not correlate with aggregate neuronal activity.
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Affiliation(s)
- Daniil P Aksenov
- NorthShore University HealthSystem, 1033 University Pl., Suite 100, Evanston, IL, 60201, USA
| | - Limin Li
- NorthShore University HealthSystem, 1033 University Pl., Suite 100, Evanston, IL, 60201, USA
| | - Michael J Miller
- NorthShore University HealthSystem, 1033 University Pl., Suite 100, Evanston, IL, 60201, USA
| | - Alice M Wyrwicz
- NorthShore University HealthSystem, 1033 University Pl., Suite 100, Evanston, IL, 60201, USA.
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Probing Neural Transplant Networks In Vivo with Optogenetics and Optogenetic fMRI. Stem Cells Int 2016; 2016:8612751. [PMID: 27293449 PMCID: PMC4880717 DOI: 10.1155/2016/8612751] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 04/18/2016] [Indexed: 01/23/2023] Open
Abstract
Understanding how stem cell-derived neurons functionally integrate into the brain upon transplantation has been a long sought-after goal of regenerative medicine. However, methodological limitations have stood as a barrier, preventing key insight into this fundamental problem. A recently developed technology, termed optogenetic functional magnetic resonance imaging (ofMRI), offers a possible solution. By combining targeted activation of transplanted neurons with large-scale, noninvasive measurements of brain activity, ofMRI can directly visualize the effect of engrafted neurons firing on downstream regions. Importantly, this tool can be used to identify not only whether transplanted neurons have functionally integrated into the brain, but also which regions they influence and how. Furthermore, the precise control afforded over activation enables the input-output properties of engrafted neurons to be systematically studied. This review summarizes the efforts in stem cell biology and neuroimaging that made this development possible and outlines its potential applications for improving and optimizing stem cell-based therapies in the future.
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Abstract
The investigation of the functional connectivity of precise neural circuits across the entire intact brain can be achieved through optogenetic functional magnetic resonance imaging (ofMRI), which is a novel technique that combines the relatively high spatial resolution of high-field fMRI with the precision of optogenetic stimulation. Fiber optics that enable delivery of specific wavelengths of light deep into the brain in vivo are implanted into regions of interest in order to specifically stimulate targeted cell types that have been genetically induced to express light-sensitive trans-membrane conductance channels, called opsins. fMRI is used to provide a non-invasive method of determining the brain's global dynamic response to optogenetic stimulation of specific neural circuits through measurement of the blood-oxygen-level-dependent (BOLD) signal, which provides an indirect measurement of neuronal activity. This protocol describes the construction of fiber optic implants, the implantation surgeries, the imaging with photostimulation and the data analysis required to successfully perform ofMRI. In summary, the precise stimulation and whole-brain monitoring ability of ofMRI are crucial factors in making ofMRI a powerful tool for the study of the connectomics of the brain in both healthy and diseased states.
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Affiliation(s)
- Peter Lin
- Neurology and Neurological Sciences, Stanford University
| | - Zhongnan Fang
- Electrical Engineering, Neurology and Neurological Sciences, Stanford University
| | - Jia Liu
- Neurology and Neurological Sciences, Stanford University
| | - Jin Hyung Lee
- Neurology and Neurological Sciences, Stanford University; Electrical Engineering, Neurology and Neurological Sciences, Stanford University;
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48
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Lebhardt P, Hohenberg CCV, Weber-Fahr W, Kelsch W, Sartorius A. Optogenetic fMRI in the mouse hippocampus: Hemodynamic response to brief glutamatergic stimuli. J Cereb Blood Flow Metab 2016; 36:629-38. [PMID: 26661158 PMCID: PMC4794094 DOI: 10.1177/0271678x15606455] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 07/24/2015] [Indexed: 01/03/2023]
Abstract
The combination of optogenetics with functional magnetic resonance imaging is a promising tool to study the causal relationship between specific neuronal populations and global brain activity. We employed this technique to study the brain response to recruitment of glutamatergic neurons in the mouse hippocampus. The light-sensitive protein channelrhodopsin-2 was expressed in α-CamKII-positive glutamatergic neurons in the left hippocampus (N = 10). Functional magnetic resonance imaging was performed during local laser stimulation, with stimulus duration of 1 second. The hemodynamic response to these stimuli was analyzed on a whole-brain level. In a secondary analysis, we examined the impact of the stimulation locus on the dorso-ventral axis within the hippocampal formation. The hemodynamic response in the mouse hippocampus had an earlier peak and a shorter duration compared to those observed in humans. Photostimulation was associated with significantly increased blood oxygen level-dependent signal in group statistics: bilaterally in the hippocampus, frontal lobe and septum, ipsilaterally in the nucleus accumbens and contralaterally in the striatum. More dorsal position of the laser fiber was associated with a stronger activation in projection regions (insular cortex and striatum). The characterization of brain-region-specific hemodynamic response functions may enable more precise interpretation of future functional magnetic resonance imaging experiments.
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Affiliation(s)
- Philipp Lebhardt
- RG Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany Shared first authorship
| | - Christian Clemm von Hohenberg
- RG Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany Shared first authorship
| | - Wolfgang Weber-Fahr
- RG Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany
| | - Wolfgang Kelsch
- RG Developmental Biology of Psychiatric Disorders, Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany Shared last authorship
| | - Alexander Sartorius
- RG Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany Shared last authorship
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49
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Yu X, He Y, Wang M, Merkle H, Dodd SJ, Silva AC, Koretsky AP. Sensory and optogenetically driven single-vessel fMRI. Nat Methods 2016; 13:337-40. [PMID: 26855362 DOI: 10.1038/nmeth.3765] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 01/07/2016] [Indexed: 01/24/2023]
Abstract
Magnetic resonance imaging (MRI) sensitivity approaches vessel specificity. We developed a single-vessel functional MRI (fMRI) method to image the contribution of vascular components to blood oxygenation level-dependent (BOLD) and cerebral blood volume (CBV) fMRI signal. We mapped individual vessels penetrating the rat somatosensory cortex with 100-ms temporal resolution by MRI with sensory or optogenetic stimulation. The BOLD signal originated primarily from venules, and the CBV signal from arterioles. The single-vessel fMRI method and its combination with optogenetics provide a platform for mapping the hemodynamic signal through the neurovascular network with specificity at the level of individual arterioles and venules.
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Affiliation(s)
- Xin Yu
- High Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
| | - Yi He
- High Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
| | - Maosen Wang
- High Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
| | - Hellmut Merkle
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, US National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen J Dodd
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, US National Institutes of Health, Bethesda, Maryland, USA
| | - Afonso C Silva
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, US National Institutes of Health, Bethesda, Maryland, USA
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, US National Institutes of Health, Bethesda, Maryland, USA
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50
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Schmid F, Wachsmuth L, Albers F, Schwalm M, Stroh A, Faber C. True and apparent optogenetic BOLD fMRI signals. Magn Reson Med 2016; 77:126-136. [PMID: 26778283 DOI: 10.1002/mrm.26095] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 10/29/2015] [Accepted: 11/25/2015] [Indexed: 01/06/2023]
Abstract
PURPOSE Optogenetic fMRI (ofMRI) is a novel tool in neurophysiology and neuroimaging. The method is prone to light-induced artifacts, two of which were investigated in this study. METHODS ofMRI was performed in rats using two excitatory opsins (ChR2 and C1V1TT ) virally transduced in somatosensory cortex or thalamus. Heat-induced apparent BOLD activation at the site of the optical fiber and stimulation light-induced activation of the visual pathways were investigated, and control experiments for these two artifacts were established. RESULTS Specific optogenetic BOLD activation was observed with both opsins, accompanied by BOLD in the visual pathways. Unspecific heat-induced BOLD was ruled out by a control experiment employing low-level constant illumination in addition to pulsed optogenetic stimulation. Activation of the visual pathways was confirmed to be physiological by direct visual stimulation of the eyes and was suppressed by additional low-level constant light to the eyes. Light inside the brain was identified as one source of the BOLD signal observed in the visual pathways. CONCLUSION ofMRI is a method of tremendous potential, but unspecific activations in fMRI not caused by the activation of opsins must be avoided or recognized as such. The control experiments presented here allow for validating the specificity of optogenetic stimulation. Magn Reson Med 77:126-136, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Florian Schmid
- Department of Clinical Radiology, University Hospital Münster, 48149, Münster, Germany
| | - Lydia Wachsmuth
- Department of Clinical Radiology, University Hospital Münster, 48149, Münster, Germany
| | - Franziska Albers
- Department of Clinical Radiology, University Hospital Münster, 48149, Münster, Germany
| | - Miriam Schwalm
- Focus Program Translational Neurosciences & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, 55128, Mainz, Germany
| | - Albrecht Stroh
- Focus Program Translational Neurosciences & Institute for Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, 55128, Mainz, Germany
| | - Cornelius Faber
- Department of Clinical Radiology, University Hospital Münster, 48149, Münster, Germany
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