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Tsai YC, Hleihil M, Otomo K, Abegg A, Cavaccini A, Panzanelli P, Cramer T, Ferrari KD, Barrett MJP, Bosshard G, Karayannis T, Weber B, Tyagarajan SK, Stobart JL. The gephyrin scaffold modulates cortical layer 2/3 pyramidal neuron responsiveness to single whisker stimulation. Sci Rep 2024; 14:4169. [PMID: 38379020 PMCID: PMC10879104 DOI: 10.1038/s41598-024-54720-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 02/15/2024] [Indexed: 02/22/2024] Open
Abstract
Gephyrin is the main scaffolding protein at inhibitory postsynaptic sites, and its clusters are the signaling hubs where several molecular pathways converge. Post-translational modifications (PTMs) of gephyrin alter GABAA receptor clustering at the synapse, but it is unclear how this affects neuronal activity at the circuit level. We assessed the contribution of gephyrin PTMs to microcircuit activity in the mouse barrel cortex by slice electrophysiology and in vivo two-photon calcium imaging of layer 2/3 (L2/3) pyramidal cells during single-whisker stimulation. Our results suggest that, depending on the type of gephyrin PTM, the neuronal activities of L2/3 pyramidal neurons can be differentially modulated, leading to changes in the size of the neuronal population responding to the single-whisker stimulation. Furthermore, we show that gephyrin PTMs have their preference for selecting synaptic GABAA receptor subunits. Our results identify an important role of gephyrin and GABAergic postsynaptic sites for cortical microcircuit function during sensory stimulation.
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Affiliation(s)
- Yuan-Chen Tsai
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Mohammad Hleihil
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Kanako Otomo
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Andrin Abegg
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Anna Cavaccini
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini, University of Turin, Turin, Italy
| | - Teresa Cramer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Giovanna Bosshard
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Theofanis Karayannis
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Shiva K Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- College of Pharmacy, University of Manitoba, Winnipeg, MB, R3E 0T5, Canada.
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Schmid F, Barrett MJP, Obrist D, Weber B, Jenny P. Red blood cells stabilize flow in brain microvascular networks. PLoS Comput Biol 2019; 15:e1007231. [PMID: 31469820 PMCID: PMC6750893 DOI: 10.1371/journal.pcbi.1007231] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 09/18/2019] [Accepted: 07/01/2019] [Indexed: 12/28/2022] Open
Abstract
Capillaries are the prime location for oxygen and nutrient exchange in all tissues. Despite their fundamental role, our knowledge of perfusion and flow regulation in cortical capillary beds is still limited. Here, we use in vivo measurements and blood flow simulations in anatomically accurate microvascular network to investigate the impact of red blood cells (RBCs) on microvascular flow. Based on these in vivo and in silico experiments, we show that the impact of RBCs leads to a bias toward equating the values of the outflow velocities at divergent capillary bifurcations, for which we coin the term “well-balanced bifurcations”. Our simulation results further reveal that hematocrit heterogeneity is directly caused by the RBC dynamics, i.e. by their unequal partitioning at bifurcations and their effect on vessel resistance. These results provide the first in vivo evidence of the impact of RBC dynamics on the flow field in the cortical microvasculature. By structural and functional analyses of our blood flow simulations we show that capillary diameter changes locally alter flow and RBC distribution. A dilation of 10% along a vessel length of 100 μm increases the flow on average by 21% in the dilated vessel downstream a well-balanced bifurcation. The number of RBCs rises on average by 27%. Importantly, RBC up-regulation proves to be more effective the more balanced the outflow velocities at the upstream bifurcation are. Taken together, we conclude that diameter changes at capillary level bear potential to locally change the flow field and the RBC distribution. Moreover, our results suggest that the balancing of outflow velocities contributes to the robustness of perfusion. Based on our in silico results, we anticipate that the bi-phasic nature of blood and small-scale regulations are essential for a well-adjusted oxygen and energy substrate supply. Glucose and oxygen are key energy sources of the brain. As energy storage capabilities are limited in the brain, a continuous supply of oxygen and glucose via the bloodstream is crucial for the brain’s functioning. The bulk of discharge occurs at the level of capillaries, which are the smallest and most frequent vessels of the cortical vasculature. Nonetheless, our understanding of perfusion and topology of the capillary bed is still limited. Here, we use in vivo two-photon based blood flow measurements and numerical simulations in large realistic microvascular networks to study the flow in the cortical microvasculature. Our results reveal that the impact of red blood cells enhances the robustness of microvascular perfusion and increases the heterogeneity in red blood cell distribution. It is well established that higher neuronal activity leads to an increase in blood flow. However, the precise regulation mechanisms and their spatial extent remain largely unknown. We show that small-scale regulations locally alter flow and red blood cell distribution. We suggest that these mechanisms are key for an efficient and flexible circulatory system. Moreover, our results reveal a novel role of the bi-phasic nature of blood.
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Affiliation(s)
- Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, Zurich, Switzerland
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- * E-mail:
| | - Matthew J. P. Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Murtenstrasse 50, Bern, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, Zurich, Switzerland
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Esipova TV, Barrett MJP, Erlebach E, Masunov AE, Weber B, Vinogradov SA. Oxyphor 2P: A High-Performance Probe for Deep-Tissue Longitudinal Oxygen Imaging. Cell Metab 2019; 29:736-744.e7. [PMID: 30686745 PMCID: PMC6402963 DOI: 10.1016/j.cmet.2018.12.022] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 10/22/2018] [Accepted: 12/26/2018] [Indexed: 01/09/2023]
Abstract
Quantitative imaging of oxygen distributions in tissue can provide invaluable information about metabolism in normal and diseased states. Two-photon phosphorescence lifetime microscopy (2PLM) has been developed to perform measurements of oxygen in vivo with micron-scale resolution in 3D; however, the method's potential has not yet been fully realized due to the limitations of current phosphorescent probe technology. Here, we report a new sensor, Oxyphor 2P, that enables oxygen microscopy twice as deep (up to 600 μm below the tissue surface) and with ∼60 times higher speed than previously possible. Oxyphor 2P allows longitudinal oxygen measurements without having to inject the probe directly into the imaged region. As proof of principle, we monitored oxygen dynamics for days following micro-stroke induced by occlusion of a single capillary in the mouse brain. Oxyphor 2P opens up new possibilities for studies of tissue metabolic states using 2PLM in a wide range of biomedical research areas.
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Affiliation(s)
- Tatiana V Esipova
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Zürich 8057, Switzerland
| | - Eva Erlebach
- Institute of Pharmacology and Toxicology, University of Zurich, Zürich 8057, Switzerland; Neuroscience Center, University of Zurich, Zurich 8057, Switzerland
| | - Artëm E Masunov
- NanoScience Technology Center, Department of Chemistry, University of Central Florida, Orlando, FL 32826, USA; School of Modeling, Simulation and Training, University of Central Florida, Orlando, FL 32826, USA; National Research Nuclear University MEPhI, Kashirskoye Shosse 31, Moscow 115409, Russia; South Ural State University, Lenin Pr. 76, Chelyabinsk 454080, Russia
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zürich 8057, Switzerland; Neuroscience Center, University of Zurich, Zurich 8057, Switzerland.
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Looser ZJ, Barrett MJP, Hirrlinger J, Weber B, Saab AS. Intravitreal AAV-Delivery of Genetically Encoded Sensors Enabling Simultaneous Two-Photon Imaging and Electrophysiology of Optic Nerve Axons. Front Cell Neurosci 2018; 12:377. [PMID: 30405358 PMCID: PMC6205974 DOI: 10.3389/fncel.2018.00377] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/03/2018] [Indexed: 11/21/2022] Open
Abstract
Myelination of axons by oligodendrocytes is a key feature of the remarkably fast operating CNS. Oligodendrocytes not only tune axonal conduction speed but are also suggested to maintain long-term axonal integrity by providing metabolic support to the axons they ensheath. However, how myelinating oligodendrocytes impact axonal energy homeostasis remains poorly understood and difficult to investigate. Here, we provide a method of how to study electrically active myelinated axons expressing genetically encoded sensors by combining electrophysiology and two-photon imaging of acutely isolated optic nerves. We show that intravitreal adeno-associated viral (AAV) vector delivery is an efficient tool to achieve functional sensor expression in optic nerve axons, which is demonstrated by measuring axonal ATP dynamics following AAV-mediated sensor expression. This novel approach allows for fast expression of any optical sensor of interest to be studied in optic nerve axons without the need to go through the laborious process of producing new transgenic mouse lines. Viral-mediated biosensor expression in myelinated axons and the subsequent combination of nerve recordings and sensor imaging outlines a powerful method to investigate oligodendroglial support functions and to further interrogate cellular mechanisms governing axonal energy homeostasis under physiological and pathological conditions.
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Affiliation(s)
- Zoe J. Looser
- Institute of Pharmacology & Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Matthew J. P. Barrett
- Institute of Pharmacology & Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
- Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
| | - Bruno Weber
- Institute of Pharmacology & Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Aiman S. Saab
- Institute of Pharmacology & Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
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Lücker A, Secomb TW, Barrett MJP, Weber B, Jenny P. The Relation Between Capillary Transit Times and Hemoglobin Saturation Heterogeneity. Part 2: Capillary Networks. Front Physiol 2018; 9:1296. [PMID: 30298017 PMCID: PMC6160581 DOI: 10.3389/fphys.2018.01296] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 08/29/2018] [Indexed: 12/22/2022] Open
Abstract
Brain metabolism is highly dependent on continuous oxygen supply. Cortical microvascular networks exhibit heterogeneous blood flow, leading to non-uniform tissue oxygenation and capillary hemoglobin saturation. We recently proposed capillary outflow saturation heterogeneity (COSH) to represent effects of heterogeneity on oxygen supply to tissue regions most vulnerable to hypoxia, and showed that diffusive oxygen exchange among red blood cells within capillaries and among capillaries (diffusive interaction) significantly reduces COSH in simplified geometrical configurations. Here, numerical simulations of oxygen transport in capillary network geometries derived from mouse somatosensory cortex are presented. Diffusive interaction was found to reduce COSH by 41 to 62% compared to simulations where diffusive interaction was excluded. Hemoglobin saturation drop across the microvascular network is strongly correlated with red blood cell transit time, but the coefficient of variation of saturation drop is approximately one third lower. Unexpectedly, the radius of the tissue cylinder supplied by a capillary correlates weakly with the anatomical tissue cylinder radius, but strongly with hemoglobin saturation. Thus, diffusive interaction contributes greatly to the microcirculation's ability to achieve tissue oxygenation, despite heterogeneous capillary transit time and hematocrit distribution. These findings provide insight into the effects of cerebral small vessel disease on tissue oxygenation and brain function.
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Affiliation(s)
- Adrien Lücker
- Department of Mechanical and Process Engineering, Institute of Fluid Dynamics, ETH Zürich, Zurich, Switzerland
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, United States
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zürich, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zürich, Zurich, Switzerland
| | - Patrick Jenny
- Department of Mechanical and Process Engineering, Institute of Fluid Dynamics, ETH Zürich, Zurich, Switzerland
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Stobart JL, Ferrari KD, Barrett MJP, Stobart MJ, Looser ZJ, Saab AS, Weber B. Long-term In Vivo Calcium Imaging of Astrocytes Reveals Distinct Cellular Compartment Responses to Sensory Stimulation. Cereb Cortex 2018; 28:184-198. [PMID: 28968832 DOI: 10.1093/cercor/bhw366] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/02/2016] [Indexed: 01/28/2023] Open
Abstract
Localized, heterogeneous calcium transients occur throughout astrocytes, but the characteristics and long-term stability of these signals, particularly in response to sensory stimulation, remain unknown. Here, we used a genetically encoded calcium indicator and an activity-based image analysis scheme to monitor astrocyte calcium activity in vivo. We found that different subcellular compartments (processes, somata, and endfeet) displayed distinct signaling characteristics. Closer examination of individual signals showed that sensory stimulation elevated the number of specific types of calcium peaks within astrocyte processes and somata, in a cortical layer-dependent manner, and that the signals became more synchronous upon sensory stimulation. Although mice genetically lacking astrocytic IP3R-dependent calcium signaling (Ip3r2-/-) had fewer signal peaks, the response to sensory stimulation was sustained, suggesting other calcium pathways are also involved. Long-term imaging of astrocyte populations revealed that all compartments reliably responded to stimulation over several months, but that the location of the response within processes may vary. These previously unknown characteristics of subcellular astrocyte calcium signals provide new insights into how astrocytes may encode local neuronal circuit activity.
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Affiliation(s)
- Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Michael J Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Zoe J Looser
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
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Stobart JL, Ferrari KD, Barrett MJP, Glück C, Stobart MJ, Zuend M, Weber B. Cortical Circuit Activity Evokes Rapid Astrocyte Calcium Signals on a Similar Timescale to Neurons. Neuron 2018; 98:726-735.e4. [PMID: 29706581 DOI: 10.1016/j.neuron.2018.03.050] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 02/12/2018] [Accepted: 03/30/2018] [Indexed: 12/22/2022]
Abstract
Sensory stimulation evokes intracellular calcium signals in astrocytes; however, the timing of these signals is disputed. Here, we used novel combinations of genetically encoded calcium indicators for concurrent two-photon imaging of cortical astrocytes and neurons in awake mice during whisker deflection. We identified calcium responses in both astrocyte processes and endfeet that rapidly followed neuronal events (∼120 ms after). These fast astrocyte responses were largely independent of IP3R2-mediated signaling and known neuromodulator activity (acetylcholine, serotonin, and norepinephrine), suggesting that they are evoked by local synaptic activity. The existence of such rapid signals implies that astrocytes are fast enough to play a role in synaptic modulation and neurovascular coupling. VIDEO ABSTRACT.
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Affiliation(s)
- Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Chaim Glück
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Michael J Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Marc Zuend
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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Schmid F, Barrett MJP, Jenny P, Weber B. Vascular density and distribution in neocortex. Neuroimage 2017; 197:792-805. [PMID: 28669910 DOI: 10.1016/j.neuroimage.2017.06.046] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/09/2017] [Accepted: 06/20/2017] [Indexed: 12/22/2022] Open
Abstract
An amazingly wide range of complex behavior emerges from the cerebral cortex. Much of the information processing that leads to these behaviors is performed in neocortical circuits that span throughout the six layers of the cortex. Maintaining this circuit activity requires substantial quantities of oxygen and energy substrates, which are delivered by the complex yet well-organized and tightly-regulated vascular system. In this review, we provide a detailed characterization of the most relevant anatomical and functional features of the cortical vasculature. This includes a compilation of the available data on laminar variation of vascular density and the topological aspects of the microvascular system. We also review the spatio-temporal dynamics of cortical blood flow regulation and oxygenation, many aspects of which remain poorly understood. Finally, we discuss some of the important implications of vascular density, distribution, oxygenation and blood flow regulation for (laminar) fMRI.
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Affiliation(s)
- Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland.
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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Mayrhofer JM, Haiss F, Haenni D, Weber S, Zuend M, Barrett MJP, Ferrari KD, Maechler P, Saab AS, Stobart JL, Wyss MT, Johannssen H, Osswald H, Palmer LM, Revol V, Schuh CD, Urban C, Hall A, Larkum ME, Rutz-Innerhofer E, Zeilhofer HU, Ziegler U, Weber B. Design and performance of an ultra-flexible two-photon microscope for in vivo research. Biomed Opt Express 2015; 6:4228-37. [PMID: 26600989 PMCID: PMC4646533 DOI: 10.1364/boe.6.004228] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 09/28/2015] [Accepted: 09/28/2015] [Indexed: 05/12/2023]
Abstract
We present a cost-effective in vivo two-photon microscope with a highly flexible frontend for in vivo research. Our design ensures fast and reproducible access to the area of interest, including rotation of imaging plane, and maximizes space for auxiliary experimental equipment in the vicinity of the animal. Mechanical flexibility is achieved with large motorized linear stages that move the objective in the X, Y, and Z directions up to 130 mm. 360° rotation of the frontend (rotational freedom for one axis) is achieved with the combination of a motorized high precision bearing and gearing. Additionally, the modular design of the frontend, based on commercially available optomechanical parts, allows straightforward updates to future scanning technologies. The design exceeds the mobility of previous movable microscope designs while maintaining high optical performance.
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Affiliation(s)
- Johannes M. Mayrhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Florent Haiss
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- IZKF Aachen, Medical Faculty of the RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
- Institute for Neuropathology, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
- Department of Ophthalmology, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Dominik Haenni
- Center for Microscopy and Image Analysis, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Institute of Anatomy, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Stefan Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Marc Zuend
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Matthew J. P. Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Philipp Maechler
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Aiman S. Saab
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Jillian L. Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Matthias T. Wyss
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Helge Johannssen
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Harald Osswald
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Lucy M. Palmer
- Florey Instittue, University of Melbourne, 30 Royal Parade, Melbourne, Victoria, 3010, Australia
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Vincent Revol
- CSEM Suisse d’Electronique et de Microtechnique, Technoparkstrasse 1, 8005 Zurich, Switzerland
| | - Claus-Dieter Schuh
- Institute of Anatomy, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Claus Urban
- CSEM Suisse d’Electronique et de Microtechnique, Technoparkstrasse 1, 8005 Zurich, Switzerland
| | - Andrew Hall
- Institute of Anatomy, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Matthew E. Larkum
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Edith Rutz-Innerhofer
- CSEM Suisse d’Electronique et de Microtechnique, Technoparkstrasse 1, 8005 Zurich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Urs Ziegler
- Center for Microscopy and Image Analysis, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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Barrett MJP, Suresh V. Extra permeability is required to model dynamic oxygen measurements: evidence for functional recruitment? J Cereb Blood Flow Metab 2013; 33:1402-11. [PMID: 23673433 PMCID: PMC3764383 DOI: 10.1038/jcbfm.2013.74] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 02/14/2013] [Accepted: 04/02/2013] [Indexed: 01/29/2023]
Abstract
Neural activation triggers a rapid, focal increase in blood flow and thus oxygen delivery. Local oxygen consumption also increases, although not to the same extent as oxygen delivery. This 'uncoupling' enables a number of widely-used functional neuroimaging techniques; however, the physiologic mechanisms that govern oxygen transport under these conditions remain unclear. Here, we explore this dynamic process using a new mathematical model. Motivated by experimental observations and previous modeling, we hypothesized that functional recruitment of capillaries has an important role during neural activation. Using conventional mechanisms alone, the model predictions were inconsistent with in vivo measurements of oxygen partial pressure. However, dynamically increasing net capillary permeability, a simple description of functional recruitment, led to predictions consistent with the data. Increasing permeability in all vessel types had the same effect, but two alternative mechanisms were unable to produce predictions consistent with the data. These results are further evidence that conventional models of oxygen transport are not sufficient to predict dynamic experimental data. The data and modeling suggest that it is necessary to include a mechanism that dynamically increases net vascular permeability. While the model cannot distinguish between the different possibilities, we speculate that functional recruitment could have this effect in vivo.
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Affiliation(s)
- Matthew J P Barrett
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
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Barrett MJP, Tawhai MH, Suresh V. Arteries dominate volume changes during brief functional hyperemia: evidence from mathematical modelling. Neuroimage 2012; 62:482-92. [PMID: 22587899 DOI: 10.1016/j.neuroimage.2012.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 04/27/2012] [Accepted: 05/04/2012] [Indexed: 10/28/2022] Open
Abstract
Variations in local neural activity are accompanied by rapid, focal changes in cerebral blood flow and volume. While a range of observations have shown that dilation occurs in cerebral arteries, there is conflicting evidence about the significance of volume changes in post-arteriole vessels. Here, we reconcile the competing observations using a new mathematical model of the hemodynamic response. First, we followed a 'top down' approach, without constraining the model, but using experimental observations at progressively more detailed scales to ensure physiological behaviour. Then, we blocked dilation of post-arteriole vessels, and predicted observations at progressively more aggregated scales (a 'bottom up' approach). Predictions of blood flow, volume, velocity, and vessel diameter changes were consistent with experimental observations. Interestingly, the model predicted small, slow increases in capillary and venous diameter in agreement with recent in vivo data. Blocking dilation in these vessels led to erroneous volume predictions. The results are further evidence that arteries make up the majority of blood volume increases during brief functional activation. However, dilation of capillaries and veins appears to be increasingly significant during extended stimulation. These are important considerations when interpreting results from different neurovascular imaging modalities.
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Affiliation(s)
- Matthew J P Barrett
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
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