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Fu P, Liu Y, Zhu L, Wang M, Yu Y, Yang F, Zhang W, Zhang H, Shoham S, Roe AW, Xi W. Two-photon imaging of excitatory and inhibitory neural response to infrared neural stimulation. NEUROPHOTONICS 2024; 11:025003. [PMID: 38800606 PMCID: PMC11125280 DOI: 10.1117/1.nph.11.2.025003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 04/29/2024] [Accepted: 04/30/2024] [Indexed: 05/29/2024]
Abstract
Significance Pulsed infrared neural stimulation (INS, 1875 nm) is an emerging neurostimulation technology that delivers focal pulsed heat to activate functionally specific mesoscale networks and holds promise for clinical application. However, little is known about its effect on excitatory and inhibitory cell types in cerebral cortex. Aim Estimates of summed population neuronal response time courses provide a potential basis for neural and hemodynamic signals described in other studies. Approach Using two-photon calcium imaging in mouse somatosensory cortex, we have examined the effect of INS pulse train application on hSyn neurons and mDlx neurons tagged with GCaMP6s. Results We find that, in anesthetized mice, each INS pulse train reliably induces robust response in hSyn neurons exhibiting positive going responses. Surprisingly, mDlx neurons exhibit negative going responses. Quantification using the index of correlation illustrates responses are reproducible, intensity-dependent, and focal. Also, a contralateral activation is observed when INS applied. Conclusions In sum, the population of neurons stimulated by INS includes both hSyn and mDlx neurons; within a range of stimulation intensities, this leads to overall excitation in the stimulated population, leading to the previously observed activations at distant post-synaptic sites.
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Affiliation(s)
- Peng Fu
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
| | - Yin Liu
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
- KU Leuven Medical School, Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, Leuven, Belgium
| | - Liang Zhu
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
- Zhejiang University, College of Biomedical Engineering and Instrument Science, Key Laboratory of Biomedical Engineering of Ministry of Education, Hangzhou, China
| | - Mengqi Wang
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
| | - Yuan Yu
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
| | - Fen Yang
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
| | - Weijie Zhang
- Zhejiang University, College of Biomedical Engineering and Instrument Science, Key Laboratory of Biomedical Engineering of Ministry of Education, Hangzhou, China
| | - Hequn Zhang
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
| | - Shy Shoham
- NYU Langone Health, Department of Ophthalmology and Tech4Health and Neuroscience Institutes, New York, New York, United States
| | - Anna Wang Roe
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
- Zhejiang University, MOE Frontier Science Center for Brain Research and Brain Machine Integration, Hangzhou, China
- Zhejiang University, NHC and CAMS Key Laboratory of Medical Neurobiology, Hangzhou, China
| | - Wang Xi
- Second Affiliated Hospital, Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, China
- Zhejiang University, MOE Frontier Science Center for Brain Research and Brain Machine Integration, Hangzhou, China
- Zhejiang University, NHC and CAMS Key Laboratory of Medical Neurobiology, Hangzhou, China
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Renden RB, Institoris A, Sharma K, Tran CHT. Modulatory effects of noradrenergic and serotonergic signaling pathway on neurovascular coupling. Commun Biol 2024; 7:287. [PMID: 38459113 PMCID: PMC10923894 DOI: 10.1038/s42003-024-05996-y] [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: 06/24/2023] [Accepted: 02/28/2024] [Indexed: 03/10/2024] Open
Abstract
Dynamic changes in astrocyte Ca2+ are recognized as contributors to functional hyperemia, a critical response to increased neuronal activity mediated by a process known as neurovascular coupling (NVC). Although the critical role of glutamatergic signaling in this process has been extensively investigated, the impact of behavioral state, and the release of behavior-associated neurotransmitters, such as norepinephrine and serotonin, on astrocyte Ca2+ dynamics and functional hyperemia have received less attention. We used two-photon imaging of the barrel cortex in awake mice to examine the role of noradrenergic and serotonergic projections in NVC. We found that both neurotransmitters facilitated sensory stimulation-induced increases in astrocyte Ca2+. Interestingly, while ablation of serotonergic neurons reduced sensory stimulation-induced functional hyperemia, ablation of noradrenergic neurons caused both attenuation and potentiation of functional hyperemia. Our study demonstrates that norepinephrine and serotonin are involved in modulating sensory stimulation-induced astrocyte Ca2+ elevations and identifies their differential effects in regulating functional hyperemia.
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Affiliation(s)
- Robert B Renden
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV, USA
| | - Adam Institoris
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Kushal Sharma
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV, USA
| | - Cam Ha T Tran
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV, USA.
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Guilbert J, Légaré A, De Koninck P, Desrosiers P, Desjardins M. Toward an integrative neurovascular framework for studying brain networks. NEUROPHOTONICS 2022; 9:032211. [PMID: 35434179 PMCID: PMC8989057 DOI: 10.1117/1.nph.9.3.032211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/11/2022] [Indexed: 05/28/2023]
Abstract
Brain functional connectivity based on the measure of blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signals has become one of the most widely used measurements in human neuroimaging. However, the nature of the functional networks revealed by BOLD fMRI can be ambiguous, as highlighted by a recent series of experiments that have suggested that typical resting-state networks can be replicated from purely vascular or physiologically driven BOLD signals. After going through a brief review of the key concepts of brain network analysis, we explore how the vascular and neuronal systems interact to give rise to the brain functional networks measured with BOLD fMRI. This leads us to emphasize a view of the vascular network not only as a confounding element in fMRI but also as a functionally relevant system that is entangled with the neuronal network. To study the vascular and neuronal underpinnings of BOLD functional connectivity, we consider a combination of methodological avenues based on multiscale and multimodal optical imaging in mice, used in combination with computational models that allow the integration of vascular information to explain functional connectivity.
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Affiliation(s)
- Jérémie Guilbert
- Université Laval, Department of Physics, Physical Engineering, and Optics, Québec, Canada
- Université Laval, Centre de recherche du CHU de Québec, Québec, Canada
| | - Antoine Légaré
- Université Laval, Department of Physics, Physical Engineering, and Optics, Québec, Canada
- Centre de recherche CERVO, Québec, Canada
- Université Laval, Department of Biochemistry, Microbiology, and Bioinformatics, Québec, Canada
| | - Paul De Koninck
- Centre de recherche CERVO, Québec, Canada
- Université Laval, Department of Biochemistry, Microbiology, and Bioinformatics, Québec, Canada
| | - Patrick Desrosiers
- Université Laval, Department of Physics, Physical Engineering, and Optics, Québec, Canada
- Centre de recherche CERVO, Québec, Canada
| | - Michèle Desjardins
- Université Laval, Department of Physics, Physical Engineering, and Optics, Québec, Canada
- Université Laval, Centre de recherche du CHU de Québec, Québec, Canada
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4
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Tran CHT. Toolbox for studying neurovascular coupling in vivo, with a focus on vascular activity and calcium dynamics in astrocytes. NEUROPHOTONICS 2022; 9:021909. [PMID: 35295714 PMCID: PMC8920490 DOI: 10.1117/1.nph.9.2.021909] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 02/23/2022] [Indexed: 05/14/2023]
Abstract
Significance: Insights into the cellular activity of each member of the neurovascular unit (NVU) is critical for understanding their contributions to neurovascular coupling (NVC)-one of the key control mechanisms in cerebral blood flow regulation. Advances in imaging and genetic tools have enhanced our ability to observe, manipulate and understand the cellular activity of NVU components, namely neurons, astrocytes, microglia, endothelial cells, vascular smooth muscle cells, and pericytes. However, there are still many unresolved questions. Since astrocytes are considered electrically unexcitable,Ca 2 + signaling is the main parameter used to monitor their activity. It is therefore imperative to study astrocyticCa 2 + dynamics simultaneously with vascular activity using tools appropriate for the question of interest. Aim: To highlight currently available genetic and imaging tools for studying the NVU-and thus NVC-with a focus on astrocyteCa 2 + dynamics and vascular activity, and discuss the utility, technical advantages, and limitations of these tools for elucidating NVC mechanisms. Approach: We draw attention to some outstanding questions regarding the mechanistic basis of NVC and emphasize the role of astrocyticCa 2 + elevations in functional hyperemia. We further discuss commonly used genetic, and optical imaging tools, as well as some newly developed imaging modalities for studying NVC at the cellular level, highlighting their advantages and limitations. Results: We provide an overview of the current state of NVC research, focusing on the role of astrocyticCa 2 + elevations in functional hyperemia; summarize recent advances in genetically engineeredCa 2 + indicators, fluorescence microscopy techniques for studying NVC; and discuss the unmet challenges for future imaging development. Conclusions: Advances in imaging techniques together with improvements in genetic tools have significantly contributed to our understanding of NVC. Many pieces of the puzzle have been revealed, but many more remain to be discovered. Ultimately, optimizing NVC research will require a concerted effort to improve imaging techniques, available genetic tools, and analytical software.
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Affiliation(s)
- Cam Ha T. Tran
- University of Nevada, Reno School of Medicine, Department of Physiology and Cell Biology, Reno, Nevada, United States
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Ahmadpour N, Kantroo M, Stobart JL. Extracellular Calcium Influx Pathways in Astrocyte Calcium Microdomain Physiology. Biomolecules 2021; 11:1467. [PMID: 34680100 PMCID: PMC8533159 DOI: 10.3390/biom11101467] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/25/2021] [Accepted: 10/01/2021] [Indexed: 02/08/2023] Open
Abstract
Astrocytes are complex glial cells that play many essential roles in the brain, including the fine-tuning of synaptic activity and blood flow. These roles are linked to fluctuations in intracellular Ca2+ within astrocytes. Recent advances in imaging techniques have identified localized Ca2+ transients within the fine processes of the astrocytic structure, which we term microdomain Ca2+ events. These Ca2+ transients are very diverse and occur under different conditions, including in the presence or absence of surrounding circuit activity. This complexity suggests that different signalling mechanisms mediate microdomain events which may then encode specific astrocyte functions from the modulation of synapses up to brain circuits and behaviour. Several recent studies have shown that a subset of astrocyte microdomain Ca2+ events occur rapidly following local neuronal circuit activity. In this review, we consider the physiological relevance of microdomain astrocyte Ca2+ signalling within brain circuits and outline possible pathways of extracellular Ca2+ influx through ionotropic receptors and other Ca2+ ion channels, which may contribute to astrocyte microdomain events with potentially fast dynamics.
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Affiliation(s)
| | | | - Jillian L. Stobart
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, 750 McDermot Avenue, Winnipeg, MG R3E 0T5, Canada; (N.A.); (M.K.)
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Li L, Tong XK, Hosseini Kahnouei M, Vallerand D, Hamel E, Girouard H. Impaired Hippocampal Neurovascular Coupling in a Mouse Model of Alzheimer's Disease. Front Physiol 2021; 12:715446. [PMID: 34475828 PMCID: PMC8406685 DOI: 10.3389/fphys.2021.715446] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/02/2021] [Indexed: 12/21/2022] Open
Abstract
Alzheimer’s disease (AD), the most common form of dementia, is characterized by neuronal degeneration and cerebrovascular dysfunction. Increasing evidence indicates that cerebrovascular dysfunction may be a key or an aggravating pathogenic factor in AD. This emphasizes the importance to investigate the tight coupling between neuronal activity and cerebral blood flow (CBF) termed neurovascular coupling (NVC). NVC depends on all cell types of the neurovascular unit within which astrocytes are important players in the progression of AD. Hence, the objective of this study was to characterize the hippocampal NVC in a mouse model of AD. Hippocampal NVC was studied in 6-month-old amyloid-beta precursor protein (APP) transgenic mice and their corresponding wild-type littermates using in vivo laser Doppler flowmetry to measure CBF in area CA1 of the hippocampus in response to Schaffer collaterals stimulation. Ex vivo two-photon microscopy experiments were performed to determine astrocytic Ca2+ and vascular responses to electrical field stimulation (EFS) or caged Ca2+ photolysis in hippocampal slices. Neuronal synaptic transmission, astrocytic endfeet Ca2+ in correlation with reactive oxygen species (ROS), and vascular reactivity in the presence or absence of Tempol, a mimetic of superoxide dismutase, were further investigated using electrophysiological, caged Ca2+ photolysis or pharmacological approaches. Whisker stimulation evoked-CBF increases and ex vivo vascular responses to EFS were impaired in APP mice compared with their age-matched controls. APP mice were also characterized by decreased basal synaptic transmission, a shorter astrocytic Ca2+ increase, and altered vascular response to elevated perivascular K+. However, long-term potentiation, astrocytic Ca2+ amplitude in response to EFS, together with vascular responses to nitric oxide remained unchanged. Importantly, we found a significantly increased Ca2+ uncaging-induced ROS production in APP mice. Tempol prevented the vascular response impairment while normalizing astrocytic Ca2+ in APP mice. These findings suggest that NVC is altered at many levels in APP mice, at least in part through oxidative stress. This points out that therapies against AD should include an antioxidative component to protect the neurovascular unit.
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Affiliation(s)
- Lin Li
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.,Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, Montréal, QC, Canada
| | - Xin-Kang Tong
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Mohammadamin Hosseini Kahnouei
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.,Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, Montréal, QC, Canada.,Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA), Université de Montréal, Montréal, QC, Canada
| | - Diane Vallerand
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.,Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA), Université de Montréal, Montréal, QC, Canada
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Hélène Girouard
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.,Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, Montréal, QC, Canada.,Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA), Université de Montréal, Montréal, QC, Canada.,Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, QC, Canada
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7
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Paquette T, Piché M, Leblond H. Contribution of astrocytes to neurovascular coupling in the spinal cord of the rat. J Physiol Sci 2021; 71:16. [PMID: 34049480 PMCID: PMC10717833 DOI: 10.1186/s12576-021-00800-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/19/2021] [Indexed: 12/13/2022]
Abstract
Functional magnetic resonance imaging (fMRI) of the spinal cord relies on the integrity of neurovascular coupling (NVC) to infer neuronal activity from hemodynamic changes. Astrocytes are a key component of cerebral NVC, but their role in spinal NVC is unclear. The objective of this study was to examine whether inhibition of astrocyte metabolism by fluorocitrate alters spinal NVC. In 14 rats, local field potential (LFP) and spinal cord blood flow (SCBF) were recorded simultaneously in the lumbosacral enlargement during noxious stimulation of the sciatic nerve before and after a local administration of fluorocitrate (N = 7) or saline (N = 7). Fluorocitrate significantly reduced SCBF responses (p < 0.001) but not LFP amplitude (p = 0.22) compared with saline. Accordingly, NVC was altered by fluorocitrate compared with saline (p < 0.01). These results support the role of astrocytes in spinal NVC and have implications for spinal cord imaging with fMRI for conditions in which astrocyte metabolism may be altered.
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Affiliation(s)
- Thierry Paquette
- Department of Anatomy, Université du Québec À Trois-Rivières, 3351 Boulevard des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada
- CogNAC Research Group, Université du Québec À Trois-Rivières, Trois-Rivières, QC, G9A 5H7, Canada
| | - Mathieu Piché
- Department of Anatomy, Université du Québec À Trois-Rivières, 3351 Boulevard des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada
- CogNAC Research Group, Université du Québec À Trois-Rivières, Trois-Rivières, QC, G9A 5H7, Canada
| | - Hugues Leblond
- Department of Anatomy, Université du Québec À Trois-Rivières, 3351 Boulevard des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada.
- CogNAC Research Group, Université du Québec À Trois-Rivières, Trois-Rivières, QC, G9A 5H7, Canada.
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