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Poplawsky AJ, Cover C, Reddy S, Chishti HB, Vazquez A, Fukuda M. Odor-evoked layer-specific fMRI activities in the awake mouse olfactory bulb. Neuroimage 2023; 274:120121. [PMID: 37080347 PMCID: PMC10240534 DOI: 10.1016/j.neuroimage.2023.120121] [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: 01/05/2023] [Revised: 03/22/2023] [Accepted: 04/17/2023] [Indexed: 04/22/2023] Open
Abstract
Awake rodent fMRI is increasingly common over the use of anesthesia since it permits behavioral paradigms and does not confound normal brain function or neurovascular coupling. It is well established that adequate acclimation to the loud fMRI environment and head fixation reduces stress in the rodents and allows for whole brain imaging with little contamination from motion. However, it is unknown whether high-resolution fMRI with increased susceptibility to motion and lower sensitivity can measure small, but spatially discrete, activations in awake mice. To examine this, we used contrast-enhanced cerebral blood volume-weighted (CBVw) fMRI in the mouse olfactory bulb for its enhanced sensitivity and neural specificity. We determined that activation patterns in the glomerular layer to four different odors were spatially distinct and were consistent with previously established histological patterns. In addition, odor-evoked laminar activations were greatest in superficial layers that decreased with laminar depth, similar to previous observations. Interestingly, the fMRI response strengths in the granule cell layer were greater in awake mice than our previous anesthetized rat studies, suggesting that feedback neural activities were intact with wakefulness. We finally determined that fMRI signal changes to repeated odor exposure (i.e., olfactory adaptation) attenuated relatively more in the feedback granule cell layer compared to the input glomerular layer, which is consistent with prior observations. We, therefore, conclude that high-resolution CBVw fMRI can measure odor-specific activation patterns and distinguish changes in laminar activity of head and body restrained awake mice.
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Affiliation(s)
- Alexander John Poplawsky
- Department of Radiology, University of Pittsburgh, McGowan Institute for Regenerative Medicine Building, 3025 E. Carson St., rm. 159, Pittsburgh, PA, 15203, United States.
| | - Christopher Cover
- Department of Radiology, University of Pittsburgh, McGowan Institute for Regenerative Medicine Building, 3025 E. Carson St., rm. 159, Pittsburgh, PA, 15203, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Sujatha Reddy
- Department of Radiology, University of Pittsburgh, McGowan Institute for Regenerative Medicine Building, 3025 E. Carson St., rm. 159, Pittsburgh, PA, 15203, United States
| | - Harris B Chishti
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Alberto Vazquez
- Department of Radiology, University of Pittsburgh, McGowan Institute for Regenerative Medicine Building, 3025 E. Carson St., rm. 159, Pittsburgh, PA, 15203, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Mitsuhiro Fukuda
- Department of Radiology, University of Pittsburgh, McGowan Institute for Regenerative Medicine Building, 3025 E. Carson St., rm. 159, Pittsburgh, PA, 15203, United States
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Pizzuti A, Huber L(R, Gulban OF, Benitez-Andonegui A, Peters J, Goebel R. Imaging the columnar functional organization of human area MT+ to axis-of-motion stimuli using VASO at 7 Tesla. Cereb Cortex 2023; 33:8693-8711. [PMID: 37254796 PMCID: PMC10321107 DOI: 10.1093/cercor/bhad151] [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: 02/11/2023] [Revised: 04/15/2023] [Accepted: 04/16/2023] [Indexed: 06/01/2023] Open
Abstract
Cortical columns of direction-selective neurons in the motion sensitive area (MT) have been successfully established as a microscopic feature of the neocortex in animals. The same property has been investigated at mesoscale (<1 mm) in the homologous brain area (hMT+, V5) in living humans by using ultra-high field functional magnetic resonance imaging (fMRI). Despite the reproducibility of the selective response to axis-of-motion stimuli, clear quantitative evidence for the columnar organization of hMT+ is still lacking. Using cerebral blood volume (CBV)-sensitive fMRI at 7 Tesla with submillimeter resolution and high spatial specificity to microvasculature, we investigate the columnar functional organization of hMT+ in 5 participants perceiving axis-of-motion stimuli for both blood oxygenation level dependent (BOLD) and vascular space occupancy (VASO) contrast mechanisms provided by the used slice-selective slab-inversion (SS-SI)-VASO sequence. With the development of a new searchlight algorithm for column detection, we provide the first quantitative columnarity map that characterizes the entire 3D hMT+ volume. Using voxel-wise measures of sensitivity and specificity, we demonstrate the advantage of using CBV-sensitive fMRI to detect mesoscopic cortical features by revealing higher specificity of axis-of-motion cortical columns for VASO as compared to BOLD contrast. These voxel-wise metrics also provide further insights on how to mitigate the highly debated draining veins effect. We conclude that using CBV-VASO fMRI together with voxel-wise measurements of sensitivity, specificity and columnarity offers a promising avenue to quantify the mesoscopic organization of hMT+ with respect to axis-of-motion stimuli. Furthermore, our approach and methodological developments are generalizable and applicable to other human brain areas where similar mesoscopic research questions are addressed.
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Affiliation(s)
- Alessandra Pizzuti
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands
- Brain Innovation, Maastricht, The Netherlands
| | - Laurentius (Renzo) Huber
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands
| | - Omer Faruk Gulban
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands
- Brain Innovation, Maastricht, The Netherlands
| | | | - Judith Peters
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands
| | - Rainer Goebel
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands
- Brain Innovation, Maastricht, The Netherlands
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Leikvoll A, Kara P. High fidelity sensory-evoked responses in neocortex after intravenous injection of genetically encoded calcium sensors. Front Neurosci 2023; 17:1181828. [PMID: 37250396 PMCID: PMC10213453 DOI: 10.3389/fnins.2023.1181828] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 04/12/2023] [Indexed: 05/31/2023] Open
Abstract
Two-photon imaging of genetically-encoded calcium indicators (GECIs) has traditionally relied on intracranial injections of adeno-associated virus (AAV) or transgenic animals to achieve expression. Intracranial injections require an invasive surgery and result in a relatively small volume of tissue labeling. Transgenic animals, although they can have brain-wide GECI expression, often express GECIs in only a small subset of neurons, may have abnormal behavioral phenotypes, and are currently limited to older generations of GECIs. Inspired by recent developments in the synthesis of AAVs that readily cross the blood brain barrier, we tested whether an alternative strategy of intravenously injecting AAV-PHP.eB is suitable for two-photon calcium imaging of neurons over many months after injection. We injected C57BL/6 J mice with AAV-PHP.eB-Synapsin-jGCaMP7s via the retro-orbital sinus. After allowing 5 to 34 weeks for expression, we performed conventional and widefield two-photon imaging of layers 2/3, 4 and 5 of the primary visual cortex. We found reproducible trial-by-trial neural responses and tuning properties consistent with known feature selectivity in the visual cortex. Thus, intravenous injection of AAV-PHP.eB does not interfere with the normal processing in neural circuits. In vivo and histological images show no nuclear expression of jGCaMP7s for at least 34 weeks post-injection.
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Affiliation(s)
| | - Prakash Kara
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
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Leikvoll A, Kara P. High fidelity sensory-evoked responses in neocortex after intravenous injection of genetically encoded calcium sensors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.09.531938. [PMID: 36945523 PMCID: PMC10028972 DOI: 10.1101/2023.03.09.531938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Two-photon imaging of genetically-encoded calcium indicators (GECIs) has traditionally relied on intracranial injections of adeno-associated virus (AAV) or transgenic animals to achieve expression. Intracranial injections require an invasive surgery and result in a relatively small volume of tissue labeling. Transgenic animals, although they can have brain-wide GECI expression, often express GECIs in only a small subset of neurons, may have abnormal behavioral phenotypes, and are currently limited to older generations of GECIs. Inspired by recent developments in the synthesis of AAVs that readily cross the blood brain barrier, we tested whether an alternative strategy of intravenously injecting AAV-PhP.eB is suitable for two-photon calcium imaging of neurons over many months after injection. We injected young (postnatal day 23 to 31) C57BL/6J mice with AAV-PhP.eB-Synapsin-jGCaMP7s via the retro-orbital sinus. After allowing 5 to 34 weeks for expression, we performed conventional and widefield two-photon imaging of layers 2/3, 4 and 5 of the primary visual cortex. We found reproducible trial-by-trial neural responses and tuning properties consistent with known feature selectivity in the visual cortex. Thus, intravenous injection of AAV-PhP.eB does not interfere with the normal processing in neural circuits. In vivo and histological images show no nuclear expression of jGCaMP7s for at least 34 weeks post-injection.
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Pfaffenrot V, Koopmans PJ. Magnetization transfer weighted laminar fMRI with multi-echo FLASH. Neuroimage 2022; 264:119725. [PMID: 36328273 DOI: 10.1016/j.neuroimage.2022.119725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 10/13/2022] [Accepted: 10/30/2022] [Indexed: 11/06/2022] Open
Abstract
Laminar functional magnetic resonance imaging (fMRI) using the gradient echo (GRE) blood oxygenation level dependent (BOLD) contrast is prone to signal changes arising from large unspecific venous vessels. Alternatives based on changes of cerebral blood volume (CBV) become more popular since it is expected that this hemodynamic response is dominant in microvasculature. One approach to sensitize the signal toward changes in CBV, and to simultaneously reduce unwanted extravascular (EV) BOLD blurring, is to selectively reduce gray matter (GM) signal via magnetization transfer (MT). In this work, we use off-resonant MT-pulses with a 3D FLASH readout to perform MT-prepared (MT-prep) laminar fMRI of the primary visual cortex (V1) at multiple echo times at 7 T. With a GRE-BOLD contrast without additional MT-weighting as reference, we investigated the influence of the MT-preparation on the shape and the echo time dependency of laminar profiles. Through numerical simulations, we optimized the sequence parameters to increase the sensitivity toward signal changes induced by changes in arterial CBV and to delineate the contributions of different compartments to the signal. We show that at 7 T, GM signals can be reduced by 30 %. Our laminar fMRI responses exhibit an increased signal change in the parenchyma at very short TE compared to a BOLD-only reference as a result of reduced EV signal intensity. By varying echo times, we could show that MT-prep results in less sensitivity toward unwanted signal changes based on changes in T2*. We conclude that when accounting for nuclear overhauser enhancement effects in blood, off-resonant MT-prep combined with efficient short TE readouts can become a promising method to reduce unwanted EV venous contributions in GRE-BOLD and/or to allow scanning at much shorter echo times without incurring a sensitivity penalty in laminar fMRI.
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Affiliation(s)
- Viktor Pfaffenrot
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, 45141 Essen, Germany; High Field and Hybrid MR Imaging, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany.
| | - Peter J Koopmans
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, 45141 Essen, Germany; High Field and Hybrid MR Imaging, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, the Netherlands
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Zhang H, Fu P, Liu Y, Zheng Z, Zhu L, Wang M, Abdellah M, He M, Qian J, Roe AW, Xi W. Large-depth three-photon fluorescence microscopy imaging of cortical microvasculature on nonhuman primates with bright AIE probe In vivo. Biomaterials 2022; 289:121809. [PMID: 36166895 DOI: 10.1016/j.biomaterials.2022.121809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 11/02/2022]
Abstract
Multiphoton microscopy has been a powerful tool in brain research, three-photon fluorescence microscopy is increasingly becoming an emerging technique for neurological research of the cortex in depth. Nonhuman primates play important roles in the study of brain science because of their neural and vascular similarity to humans. However, there are few research results of three-photon fluorescence microscopy on the brain of nonhuman primates due to the lack of optimized imaging systems and excellent fluorescent probes. Here we introduced a bright aggregation-induced emission (AIE) probe with excellent three-photon fluorescence efficiency as well as facile synthesis process and we validated its biocompatibility in the macaque monkey. We achieved a large-depth vascular imaging of approximately 1 mm in the cerebral cortex of macaque monkey with our lab-modified three-photon fluorescence microscopy system and the AIE probe. Functional measurement of blood velocity in deep cortex capillaries was also performed. Furthermore, the comparison of cortical deep vascular structure parameters across species was presented on the monkey and mouse cortex. This work is the first in vivo three-photon fluorescence microscopic imaging research on the macaque monkey cortex reaching the imaging depth of ∼1 mm with the bright AIE probe. The results demonstrate the potential of three-photon microscopy as primate-compatible method for imaging fine vascular networks and will advance our understanding of vascular function in normal and disease in humans.
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Affiliation(s)
- Hequn Zhang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China; State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, 310058, China
| | - Peng Fu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Yin Liu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Zheng Zheng
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, 230009, China
| | - Liang Zhu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, China
| | - Mengqi Wang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Marwan Abdellah
- Blue Brain Project (BBP), École Polytechnique Fédérale de Lausanne (EPFL), Campus Biotech, 1202, Geneva, Switzerland
| | - Mubin He
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, 310058, China
| | - Jun Qian
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, 310058, China.
| | - Anna Wang Roe
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Wang Xi
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China; Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, China
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