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Xie Z, Dong S, Zhang Y, Yuan Y. Transcranial ultrasound stimulation at the peak-phase of theta-cycles in the hippocampus improve memory performance. Neuroimage 2023; 283:120423. [PMID: 37884166 DOI: 10.1016/j.neuroimage.2023.120423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 10/28/2023] Open
Abstract
The present study aimed to investigate the effectiveness of closed-loop transcranial ultrasound stimulation (closed-loop TUS) as a non-invasive, high temporal-spatial resolution method for modulating brain function to enhance memory. For this purpose, we applied closed-loop TUS to the CA1 region of the rat hippocampus for 7 consecutive days at different phases of theta cycles. Following the intervention, we evaluated memory performance through behavioral testing and recorded the neural activity. Our results indicated that closed-loop TUS applied at the peak phase of theta cycles significantly improves the memory performance in rats, as evidenced by behavioral testing. Furthermore, we observed that closed-loop TUS modifies the power and cross-frequency coupling strength of local field potentials (LFPs) during memory task, as well as modulates neuronal activity patterns and synaptic transmission, depending on phase of stimulation relative to theta rhythm. We demonstrated that closed-loop TUS can modulate neural activity and memory performance in a phase-dependent manner. Specifically, we observed that effectiveness of closed-loop TUS in regulating neural activity and memory is dependent on the timing of stimulation in relation to different theta phase. The findings implied that closed-loop TUS may have the capability to alter neural activity and memory performance in a phase-sensitive manner, and suggested that the efficacy of closed-loop TUS in modifying neural activity and memory was contingent on timing of stimulation with respect to the theta rhythm. Moreover, the improvement in memory performance after closed-loop TUS was found to be persistent.
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Affiliation(s)
- Zhenyu Xie
- School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China; Key Laboratory of Intelligent Rehabilitation and Neuromodulation of Hebei Province, Yanshan University, Qinhuangdao 066004, China
| | - Shuxun Dong
- School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China; Key Laboratory of Intelligent Rehabilitation and Neuromodulation of Hebei Province, Yanshan University, Qinhuangdao 066004, China
| | - Yiyao Zhang
- Neuroscience Institute, NYU Langone Health, New York 10016, USA.
| | - Yi Yuan
- School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China; Key Laboratory of Intelligent Rehabilitation and Neuromodulation of Hebei Province, Yanshan University, Qinhuangdao 066004, China.
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Chen HF, Lambers H, Nagelmann N, Sandbrink M, Segelcke D, Pogatzki-Zahn E, Faber C, Pradier B. Generation of a whole-brain hemodynamic response function and sex-specific differences in cerebral processing of mechano-sensation in mice detected by BOLD fMRI. Front Neurosci 2023; 17:1187328. [PMID: 37700753 PMCID: PMC10493293 DOI: 10.3389/fnins.2023.1187328] [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: 03/15/2023] [Accepted: 07/05/2023] [Indexed: 09/14/2023] Open
Abstract
BOLD fMRI has become a prevalent method to study cerebral sensory processing in rodent disease models, including pain and mechanical hypersensitivity. fMRI data analysis is frequently combined with a general-linear-model (GLM) -based analysis, which uses the convolution of a hemodynamic response function (HRF) with the stimulus paradigm. However, several studies indicated that the HRF differs across species, sexes, brain structures, and experimental factors, including stimulation modalities or anesthesia, and hence might strongly affect the outcome of BOLD analyzes. While considerable work has been done in humans and rats to understand the HRF, much less is known in mice. As a prerequisite to investigate mechano-sensory processing and BOLD fMRI data in male and female mice, we (1) designed a rotating stimulator that allows application of two different mechanical modalities, including innocuous von Frey and noxious pinprick stimuli and (2) determined and statistically compared HRFs across 30 brain structures and experimental conditions, including sex and, stimulus modalities. We found that mechanical stimulation lead to brain-wide BOLD signal changes thereby allowing extraction of HRFs from multiple brain structures. However, we did not find differences in HRFs across all brain structures and experimental conditions. Hence, we computed a whole-brain mouse HRF, which is based on 88 functional scans from 30 mice. A comparison of this mouse-specific HRF with our previously reported rat-derived HRF showed significantly slower kinetics in mice. Finally, we detected pronounced differences in cerebral BOLD activation between male and female mice with mechanical stimulation, thereby exposing divergent processing of noxious and innocuous stimuli in both sexes.
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Affiliation(s)
- Hui-Fen Chen
- Clinic of Radiology, Translational Research Imaging Center (TRIC), University of Münster, Münster, Germany
| | - Henriette Lambers
- Clinic of Radiology, Translational Research Imaging Center (TRIC), University of Münster, Münster, Germany
| | - Nina Nagelmann
- Clinic of Radiology, Translational Research Imaging Center (TRIC), University of Münster, Münster, Germany
| | - Martin Sandbrink
- Clinic of Radiology, Translational Research Imaging Center (TRIC), University of Münster, Münster, Germany
| | - Daniel Segelcke
- Department of Anesthesiology, Intensive Care and Pain Medicine, University of Münster, Münster, Germany
| | - Esther Pogatzki-Zahn
- Department of Anesthesiology, Intensive Care and Pain Medicine, University of Münster, Münster, Germany
| | - Cornelius Faber
- Clinic of Radiology, Translational Research Imaging Center (TRIC), University of Münster, Münster, Germany
| | - Bruno Pradier
- Clinic of Radiology, Translational Research Imaging Center (TRIC), University of Münster, Münster, Germany
- Department of Anesthesiology, Intensive Care and Pain Medicine, University of Münster, Münster, Germany
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Segeroth M, Wachsmuth L, Gagel M, Albers F, Hess A, Faber C. Disentangling the impact of cerebrospinal fluid formation and neuronal activity on solute clearance from the brain. Fluids Barriers CNS 2023; 20:43. [PMID: 37316849 DOI: 10.1186/s12987-023-00443-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 05/18/2023] [Indexed: 06/16/2023] Open
Abstract
BACKGROUND Despite recent attention, pathways and mechanisms of fluid transposition in the brain are still a matter of intense discussion and driving forces underlying waste clearance in the brain remain elusive. Consensus exists that net solute transport is a prerequisite for efficient clearance. The individual impact of neuronal activity and cerebrospinal fluid (CSF) formation, which both vary with brain state and anesthesia, remain unclear. METHODS To separate conditions with high and low neuronal activity and high and low CSF formation, different anesthetic regimens in naive rat were established, using Isoflurane (ISO), Medetomidine (MED), acetazolamide or combinations thereof. With dynamic contrast-enhanced MRI, after application of low molecular weight contrast agent (CA) Gadobutrol to cisterna magna, tracer distribution was monitored as surrogate for solute clearance. Simultaneous fiber-based Ca2+-recordings informed about the state of neuronal activity under different anesthetic regimen. T2-weighted MRI and diffusion-weighted MRI (DWI) provided size of subarachnoidal space and aqueductal flow as surrogates for CSF formation. Finally, a pathway and mechanism-independent two-compartment model was introduced to provide a measure of efficiency for solute clearance from the brain. RESULTS Anatomical imaging, DWI and Ca2+-recordings confirmed that conditions with distinct levels of neuronal activity and CSF formation were achieved. A sleep-resembling condition, with reduced neuronal activity and enhanced CSF formation was achieved using ISO+MED and an awake-like condition with high neuronal activity using MED alone. CA distribution in the brain correlated with the rate of CSF formation. The cortical brain state had major influence on tracer diffusion. Under conditions with low neuronal activity, higher diffusivity suggested enlargement of extracellular space, facilitating a deeper permeation of solutes into brain parenchyma. Under conditions with high neuronal activity, diffusion of solutes into parenchyma was hindered and clearance along paravascular pathways facilitated. Exclusively based on the measured time signal curves, the two-compartment model provided net exchange ratios, which were significantly larger for the sleep-resembling condition than for the awake-like condition. CONCLUSIONS Efficiency of solute clearance in brain changes with alterations in both state of neuronal activity and CSF formation. Our clearance pathway and mechanism agnostic kinetic model informs about net solute transport, solely based on the measured time signal curves. This rather simplifying approach largely accords with preclinical and clinical findings.
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Affiliation(s)
- Martin Segeroth
- Translational Research Imaging Center (TRIC), Clinic of Radiology, University of Münster, Albert-Schweitzer-Campus 1, Gebäude A16, 48149, Münster, Germany
- Department of Radiology, University Hospital Basel, Basel, Switzerland
| | - Lydia Wachsmuth
- Translational Research Imaging Center (TRIC), Clinic of Radiology, University of Münster, Albert-Schweitzer-Campus 1, Gebäude A16, 48149, Münster, Germany
| | - Mathias Gagel
- Translational Research Imaging Center (TRIC), Clinic of Radiology, University of Münster, Albert-Schweitzer-Campus 1, Gebäude A16, 48149, Münster, Germany
| | - Franziska Albers
- Translational Research Imaging Center (TRIC), Clinic of Radiology, University of Münster, Albert-Schweitzer-Campus 1, Gebäude A16, 48149, Münster, Germany
| | - Andreas Hess
- Department of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
- Institute of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
- FAU NeW, Research Center for New Bioactive Compounds, Nikolaus-Fiebiger-Str. 10, 91058, Erlangen, Germany
| | - Cornelius Faber
- Translational Research Imaging Center (TRIC), Clinic of Radiology, University of Münster, Albert-Schweitzer-Campus 1, Gebäude A16, 48149, Münster, Germany.
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Cabral J, Fernandes FF, Shemesh N. Intrinsic macroscale oscillatory modes driving long range functional connectivity in female rat brains detected by ultrafast fMRI. Nat Commun 2023; 14:375. [PMID: 36746938 PMCID: PMC9902553 DOI: 10.1038/s41467-023-36025-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 01/12/2023] [Indexed: 02/08/2023] Open
Abstract
Spontaneous fluctuations in functional magnetic resonance imaging (fMRI) signals correlate across distant brain areas, shaping functionally relevant intrinsic networks. However, the generative mechanism of fMRI signal correlations, and in particular the link with locally-detected ultra-slow oscillations, are not fully understood. To investigate this link, we record ultrafast ultrahigh field fMRI signals (9.4 Tesla, temporal resolution = 38 milliseconds) from female rats across three anesthesia conditions. Power at frequencies extending up to 0.3 Hz is detected consistently across rat brains and is modulated by anesthesia level. Principal component analysis reveals a repertoire of modes, in which transient oscillations organize with fixed phase relationships across distinct cortical and subcortical structures. Oscillatory modes are found to vary between conditions, resonating at faster frequencies under medetomidine sedation and reducing both in number, frequency, and duration with the addition of isoflurane. Peaking in power within clear anatomical boundaries, these oscillatory modes point to an emergent systemic property. This work provides additional insight into the origin of oscillations detected in fMRI and the organizing principles underpinning spontaneous long-range functional connectivity.
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Affiliation(s)
- Joana Cabral
- Preclinical MRI Lab, Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal. .,Life and Health Sciences Research Institute, School of Medicine, University of Minho, Braga, Portugal. .,ICVS/3B's - Portuguese Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Francisca F Fernandes
- Preclinical MRI Lab, Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
| | - Noam Shemesh
- Preclinical MRI Lab, Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal.
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Tillet Y. Magnetic Resonance Imaging, a New Tool for Neuroendocrine Research in Sheep. Neuroendocrinology 2023; 113:208-215. [PMID: 35051936 DOI: 10.1159/000522087] [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] [Received: 10/06/2021] [Accepted: 01/06/2022] [Indexed: 11/19/2022]
Abstract
Magnetic resonance imaging (MRI) brain analysis is used in rodents and for clinical investigation in humans, and it becomes also possible now for large animal models studies. Specific facilities are available with clinical scanners and benefit to neuroendocrine investigations in sheep. Sheep has a large gyrencephalic brain and its organization is very similar to primates and human, and among physiological regulations, oestrous cycle of the ewes is similar to women. Therefore, this animal is a good model for preclinical researches using MRI, as illustrated with steroids impact on the brain. New data were obtained concerning the effect of sexual steroids on neuronal networks involved in the control of reproduction and in the influence of sexual steroids on cognition. In addition to the importance of such data for understanding the role of these hormones on brain functions, they give new insights to consider the sheep as a powerful model for preclinical studies in the field of neuroendocrinology. These points are discussed in this short review.
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Affiliation(s)
- Yves Tillet
- CNRS UMR 7247, IFCE, INRAE, University of Tours, Physiologie de la Reproduction et des Comportements, Nouzilly, France
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Lambers H, Wachsmuth L, Lippe C, Faber C. The impact of vasomotion on analysis of rodent fMRI data. Front Neurosci 2023; 17:1064000. [PMID: 36908777 PMCID: PMC9998505 DOI: 10.3389/fnins.2023.1064000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/06/2023] [Indexed: 03/14/2023] Open
Abstract
Introduction Small animal fMRI is an essential part of translational research in the cognitive neurosciences. Due to small dimensions and animal physiology preclinical fMRI is prone to artifacts that may lead to misinterpretation of the data. To reach unbiased translational conclusions, it is, therefore, crucial to identify potential sources of experimental noise and to develop correction methods for contributions that cannot be avoided such as physiological noise. Aim of this study was to assess origin and prevalence of hemodynamic oscillations (HDO) in preclinical fMRI in rat, as well as their impact on data analysis. Methods Following the development of algorithms for HDO detection and suppression, HDO prevalence in fMRI measurements was investigated for different anesthetic regimens, comprising isoflurane and medetomidine, and for both gradient echo and spin echo fMRI sequences. In addition to assessing the effect of vasodilation on HDO, it was studied if HDO have a direct neuronal correlate using local field potential (LFP) recordings. Finally, the impact of HDO on analysis of fMRI data was assessed, studying both the impact on calculation of activation maps as well as the impact on brain network analysis. Overall, 303 fMRI measurements and 32 LFP recordings were performed in 71 rats. Results In total, 62% of the fMRI measurements showed HDO with a frequency of (0.20 ± 0.02) Hz. This frequent occurrence indicated that HDO cannot be generally neglected in fMRI experiments. Using the developed algorithms, HDO were detected with a specificity of 95%, and removed efficiently from the signal time courses. HDO occurred brain-wide under vasoconstrictive conditions in both small and large blood vessels. Vasodilation immediately interrupted HDO, which, however, returned within 1 h under vasoconstrictive conditions. No direct neuronal correlate of HDO was observed in LFP recordings. HDO significantly impacted analysis of fMRI data, leading to altered cluster sizes and F-values for activated voxels, as well as altered brain networks, when comparing data with and without HDO. Discussion We therefore conclude that HDO are caused by vasomotion under certain anesthetic conditions and should be corrected during fMRI data analysis to avoid bias.
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Affiliation(s)
| | - Lydia Wachsmuth
- Clinic of Radiology, University of Münster, Münster, Germany
| | - Chris Lippe
- Clinic of Radiology, University of Münster, Münster, Germany
| | - Cornelius Faber
- Clinic of Radiology, University of Münster, Münster, Germany
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7
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Vedaei F, Alizadeh M, Tantawi M, Romo V, Mohamed FB, Wu C. Vascular and neuronal effects of general anesthesia on the brain: An fMRI study. J Neuroimaging 2023; 33:109-120. [PMID: 36097249 DOI: 10.1111/jon.13049] [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: 07/22/2022] [Revised: 08/30/2022] [Accepted: 08/30/2022] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND AND PURPOSE A number of functional magnetic resonance imaging (fMRI) studies rely on application of anesthetic agents during scanning that can modulate and complicate interpretation of the measured hemodynamic blood oxygenation level-dependent (BOLD) response. The purpose of the present study was to investigate the effect of general anesthesia on two main components of BOLD signal including neuronal activity and vascular response. METHODS Breath-holding (BH) fMRI was conducted in wakefulness and under anesthesia states in 9 patients with drug-resistant epilepsy who needed to get scanned under anesthesia during laser interstitial thermal therapy. BOLD and BOLD cerebrovascular reactivity (BOLD-CVR) maps were compared using t-test between two states to assess the effect of anesthesia on neuronal activity and vascular factors (p < .05). RESULTS Overall, our findings revealed an increase in BOLD-CVR and decrease in BOLD response under anesthesia in several brain regions. The results proposed that the modulatory mechanism of anesthetics on neuronal and vascular components of BOLD signal may work in different ways. CONCLUSION This experiment for the first human study showed that anesthesia may play an important role in dissociation between neuronal and vascular responses contributed to hemodynamic BOLD signal using BH fMRI imaging that may assist the implication of general anesthesia and interpretation of outcomes in clinical setting.
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Affiliation(s)
- Faezeh Vedaei
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Mahdi Alizadeh
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Department of Neurological Surgery, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Mohamed Tantawi
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Victor Romo
- Department of Anesthesiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Feroze B Mohamed
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Chengyuan Wu
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Department of Neurological Surgery, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Lambers H, Wachsmuth L, Thomas D, Boumezbeur F, Hoesker V, Pradier B, Faber C. Fiber-based lactate recordings with fluorescence resonance energy transfer sensors by applying an magnetic resonance-informed correction of hemodynamic artifacts. NEUROPHOTONICS 2022; 9:032212. [PMID: 35558647 PMCID: PMC9084224 DOI: 10.1117/1.nph.9.3.032212] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/06/2022] [Indexed: 06/15/2023]
Abstract
Significance: Fluorescence resonance energy transfer (FRET) sensors offer enormous benefits when studying neurophysiology through confocal microscopy. Yet, their use for fiber-based in vivo recordings is hampered by massive confounding effects and has therefore been scarcely reported. Aim: We aim to investigate whether in vivo fiber-based lactate recordings in the rodent brain are feasible with FRET sensors and implement a correction algorithm for the predominant hemodynamic artifact. Approach: We performed fiber-based FRET recordings of lactate (Laconic) and calcium (Twitch-2B) simultaneously with functional MRI and pharmacological MRI. MR-derived parameters were applied to correct hemodynamic artifacts. Results of FRET measurements were validated by local field potential, magnetic resonance spectroscopy, and blood analysis. Results: Hemodynamic artifacts dominated fiber-based in vivo FRET measurements with both Laconic and Twitch-2B. Our MR-based correction algorithm enabled to remove the artifacts and detect lactate and calcium changes during sensory stimulation or intravenous lactate injections. Conclusions: In vivo fiber-based lactate recordings are feasible using FRET-based sensors. However, signal corrections are required. MR-derived hemodynamic parameters can successfully be applied for artifact correction.
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Affiliation(s)
- Henriette Lambers
- University Hospital Münster, Translational Research Imaging Center (TRIC), Clinic for Radiology, Münster, Germany
| | - Lydia Wachsmuth
- University Hospital Münster, Translational Research Imaging Center (TRIC), Clinic for Radiology, Münster, Germany
| | - Dominik Thomas
- University Hospital Münster, Translational Research Imaging Center (TRIC), Clinic for Radiology, Münster, Germany
| | - Fawzi Boumezbeur
- NeuroSpin, CEA, CNRS, Paris-Saclay University, Gif-Sur-Yvette, France
| | - Vanessa Hoesker
- University Hospital Münster, Translational Research Imaging Center (TRIC), Clinic for Radiology, Münster, Germany
| | - Bruno Pradier
- University Hospital Münster, Translational Research Imaging Center (TRIC), Clinic for Radiology, Münster, Germany
| | - Cornelius Faber
- University Hospital Münster, Translational Research Imaging Center (TRIC), Clinic for Radiology, Münster, Germany
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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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Cleppien D, Aedo-Jury F, Stroh A. Beyond correlation: functional OPTO-MAgnetic Integration Concept (OPTOMAIC) to reveal the brain-wide signature of local neuronal signals-of-interest. NEUROPHOTONICS 2022; 9:032213. [PMID: 35813935 PMCID: PMC9259002 DOI: 10.1117/1.nph.9.3.032213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
Significance: Due to the vascular origin of the fMRI signal, the spatiotemporally precise interpretation of the blood oxygen level-dependent (BOLD) response as brain-wide correlate of neuronal activity is limited. Optical fiber-based neuronal calcium recordings provide a specific and temporally highly resolved signal yet lacking brain-wide coverage. The cross-modal integration of both modalities holds the potential for unique synergies. Aim: The OPTO-MAgnetic Integration Concept (OPTOMAIC) extracts the very fraction of the BOLD response that reacts to optically recorded neuronal signals-of-interest. Approach and Results: First, OPTOMAIC identifies the trials containing neuronal signal-of-interest (SoI) in the optical recordings. The long duration of the BOLD response is considered by calculating and thresholding neuronal interevent intervals. The resulting optical regression vector is probed for a positive BOLD response with single-event and single-voxel resolution, generating a BOLD response matrix containing only those events and voxels with both a neuronal SoI and a positive fMRI signal increase. Last, the onset of the BOLD response is being quantified, representing the section of the BOLD response most reliably reporting at least components of the neuronal signal. Conclusions: The seven OPTOMAIC steps result in a brain-wide BOLD signature reflecting the underlying neuronal SoI with utmost cross-modal integration depth and taking full advantage of the specific strengths of each method.
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Affiliation(s)
- Dirk Cleppien
- Leibniz Institute for Resilience Research, Mainz, Germany
| | | | - Albrecht Stroh
- Leibniz Institute for Resilience Research, Mainz, Germany
- Institute of Pathophysiology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
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Ni R. Magnetic Resonance Imaging in Tauopathy Animal Models. Front Aging Neurosci 2022; 13:791679. [PMID: 35145392 PMCID: PMC8821905 DOI: 10.3389/fnagi.2021.791679] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
The microtubule-associated protein tau plays an important role in tauopathic diseases such as Alzheimer's disease and primary tauopathies such as progressive supranuclear palsy and corticobasal degeneration. Tauopathy animal models, such as transgenic, knock-in mouse and rat models, recapitulating tauopathy have facilitated the understanding of disease mechanisms. Aberrant accumulation of hyperphosphorylated tau contributes to synaptic deficits, neuroinflammation, and neurodegeneration, leading to cognitive impairment in animal models. Recent advances in molecular imaging using positron emission tomography (PET) and magnetic resonance imaging (MRI) have provided valuable insights into the time course of disease pathophysiology in tauopathy animal models. High-field MRI has been applied for in vivo imaging in animal models of tauopathy, including diffusion tensor imaging for white matter integrity, arterial spin labeling for cerebral blood flow, resting-state functional MRI for functional connectivity, volumetric MRI for neurodegeneration, and MR spectroscopy. In addition, MR contrast agents for non-invasive imaging of tau have been developed recently. Many preclinical MRI indicators offer excellent translational value and provide a blueprint for clinical MRI in the brains of patients with tauopathies. In this review, we summarized the recent advances in using MRI to visualize the pathophysiology of tauopathy in small animals. We discussed the outstanding challenges in brain imaging using MRI in small animals and propose a future outlook for visualizing tau-related alterations in the brains of animal models.
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Affiliation(s)
- Ruiqing Ni
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
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12
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Walton LR, Verber M, Lee SH, Chao THH, Wightman RM, Shih YYI. Simultaneous fMRI and fast-scan cyclic voltammetry bridges evoked oxygen and neurotransmitter dynamics across spatiotemporal scales. Neuroimage 2021; 244:118634. [PMID: 34624504 PMCID: PMC8667333 DOI: 10.1016/j.neuroimage.2021.118634] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/10/2021] [Accepted: 10/04/2021] [Indexed: 12/24/2022] Open
Abstract
The vascular contributions of neurotransmitters to the hemodynamic response are gaining more attention in neuroimaging studies, as many neurotransmitters are vasomodulatory. To date, well-established electrochemical techniques that detect neurotransmission in high magnetic field environments are limited. Here, we propose an experimental setting enabling simultaneous fast-scan cyclic voltammetry (FSCV) and blood oxygenation level-dependent functional magnetic imaging (BOLD fMRI) to measure both local tissue oxygen and dopamine responses, and global BOLD changes, respectively. By using MR-compatible materials and the proposed data acquisition schemes, FSCV detected physiological analyte concentrations with high temporal resolution and spatial specificity inside of a 9.4 T MRI bore. We found that tissue oxygen and BOLD correlate strongly, and brain regions that encode dopamine amplitude differences can be identified via modeling simultaneously acquired dopamine FSCV and BOLD fMRI time-courses. This technique provides complementary neurochemical and hemodynamic information and expands the scope of studying the influence of local neurotransmitter release over the entire brain.
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Affiliation(s)
- Lindsay R Walton
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America.
| | - Matthew Verber
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Sung-Ho Lee
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Tzu-Hao Harry Chao
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - R Mark Wightman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Yen-Yu Ian Shih
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America.
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13
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Pradier B, Wachsmuth L, Nagelmann N, Segelcke D, Kreitz S, Hess A, Pogatzki-Zahn EM, Faber C. Combined resting state-fMRI and calcium recordings show stable brain states for task-induced fMRI in mice under combined ISO/MED anesthesia. Neuroimage 2021; 245:118626. [PMID: 34637903 DOI: 10.1016/j.neuroimage.2021.118626] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 09/27/2021] [Indexed: 11/28/2022] Open
Abstract
For fMRI in animal models, the combination of low-dose anesthetic, isoflurane (ISO), and the sedative medetomidine (MED) has recently become an advocated regimen to achieve stable neuronal states and brain networks in rats that are required for reliable task-induced BOLD fMRI. However, in mice the temporal stability of neuronal states and networks in resting-state (rs)-fMRI experiments during the combined ISO/MED regimen has not been systematically investigated. Using a multimodal approach with optical calcium (Ca2+) recordings and rs-fMRI, we investigated cortical neuronal/astrocytic Ca2+activity states and brain networks at multiple time points while switching from anesthesia with 1% ISO to a combined ISO/MED regimen. We found that cortical activity states reached a steady-state 45 min following start of MED infusion as indicated by stable Ca2+ transients. Similarly, rs-networks were not statistically different between anesthesia with ISO and the combined ISO/MED regimen 45 and 100 min after start of MED. Importantly, during the transition time we identified changed rs-network signatures that likely reflect the different mode of action of the respective anesthetic; these included a dose-dependent increase in cortico-cortical functional connectivity (FC) presumably caused by reduction of ISO concentration and decreased FC in subcortical arousal nuclei due to MED infusion. Furthermore, we report detection of visual stimulation-induced BOLD fMRI during the stable ISO/MED neuronal state 45 min after induction. Based on our findings, we recommend a 45-minute waiting period after switching from ISO anesthesia to the combined ISO/MED regimen before performing rs- or task-induced fMRI experiments.
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Affiliation(s)
- Bruno Pradier
- Department of Clinical Radiology, Translational Research Imaging Center, University Hospital Münster, Münster 48149, Germany; Department of Anesthesiology Intensive Care and Pain Medicine, University Hospital Münster, Germany
| | - Lydia Wachsmuth
- Department of Clinical Radiology, Translational Research Imaging Center, University Hospital Münster, Münster 48149, Germany
| | - Nina Nagelmann
- Department of Clinical Radiology, Translational Research Imaging Center, University Hospital Münster, Münster 48149, Germany
| | - Daniel Segelcke
- Department of Anesthesiology Intensive Care and Pain Medicine, University Hospital Münster, Germany
| | - Silke Kreitz
- Institute of Experimental and Clinical Pharmacology and Toxicology, Emil Fischer Center, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Andreas Hess
- Institute of Experimental and Clinical Pharmacology and Toxicology, Emil Fischer Center, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Esther M Pogatzki-Zahn
- Department of Anesthesiology Intensive Care and Pain Medicine, University Hospital Münster, Germany
| | - Cornelius Faber
- Department of Clinical Radiology, Translational Research Imaging Center, University Hospital Münster, Münster 48149, Germany.
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14
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Berndt N, Kovács R, Schoknecht K, Rösner J, Reiffurth C, Maechler M, Holzhütter HG, Dreier JP, Spies C, Liotta A. Low neuronal metabolism during isoflurane-induced burst suppression is related to synaptic inhibition while neurovascular coupling and mitochondrial function remain intact. J Cereb Blood Flow Metab 2021; 41:2640-2655. [PMID: 33899556 PMCID: PMC8504408 DOI: 10.1177/0271678x211010353] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Deep anaesthesia may impair neuronal, vascular and mitochondrial function facilitating neurological complications, such as delirium and stroke. On the other hand, deep anaesthesia is performed for neuroprotection in critical brain diseases such as status epilepticus or traumatic brain injury. Since the commonly used anaesthetic propofol causes mitochondrial dysfunction, we investigated the impact of the alternative anaesthetic isoflurane on neuro-metabolism. In deeply anaesthetised Wistar rats (burst suppression pattern), we measured increased cortical tissue oxygen pressure (ptiO2), a ∼35% drop in regional cerebral blood flow (rCBF) and burst-associated neurovascular responses. In vitro, 3% isoflurane blocked synaptic transmission and impaired network oscillations, thereby decreasing the cerebral metabolic rate of oxygen (CMRO2). Concerning mitochondrial function, isoflurane induced a reductive shift in flavin adenine dinucleotide (FAD) and decreased stimulus-induced FAD transients as Ca2+ influx was reduced by ∼50%. Computer simulations based on experimental results predicted no direct effects of isoflurane on mitochondrial complexes or ATP-synthesis. We found that isoflurane-induced burst suppression is related to decreased ATP consumption due to inhibition of synaptic activity while neurovascular coupling and mitochondrial function remain intact. The neurometabolic profile of isoflurane thus appears to be superior to that of propofol which has been shown to impair the mitochondrial respiratory chain.
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Affiliation(s)
- Nikolaus Berndt
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Richard Kovács
- Institute for Neurophysiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Karl Schoknecht
- Carl-Ludwig-Institute for Physiology, University Leipzig, Leipzig, Germany
| | - Jörg Rösner
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Clemens Reiffurth
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Mathilde Maechler
- Institute for Neurophysiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Jens P Dreier
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Bernstein center for Computational Neuroscience, Charité - Universitätsmedizin, Humboldt-Universität zu Berlin and Technische Universität Berlin, Berlin, Germany.,Einstein Center for Neuroscience, Charité - Universitätsmedizin Berlin, the Freie Universität Berlin, the Humboldt-Universität zu Berlin and the Technische Universität Berlin, Berlin, Germany
| | - Claudia Spies
- Department of Anesthesiology and Intensive Care, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.,Berlin Institute of Health, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Agustin Liotta
- Institute for Neurophysiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Anesthesiology and Intensive Care, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.,Berlin Institute of Health, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
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15
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Characterization of brain-wide somatosensory BOLD fMRI in mice under dexmedetomidine/isoflurane and ketamine/xylazine. Sci Rep 2021; 11:13110. [PMID: 34162952 PMCID: PMC8222234 DOI: 10.1038/s41598-021-92582-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/10/2021] [Indexed: 02/05/2023] Open
Abstract
Mouse fMRI under anesthesia has become increasingly popular due to improvement in obtaining brain-wide BOLD response. Medetomidine with isoflurane has become well-accepted for resting-state fMRI, but whether this combination allows for stable, expected, and robust brain-wide evoked response in mice has yet to be validated. We thus utilized intravenous infusion of dexmedetomidine with inhaled isoflurane and intravenous infusion of ketamine/xylazine to elucidate whether stable mouse physiology and BOLD response are obtainable in response to simultaneous forepaw and whisker-pad stimulation throughout 8 h. We found both anesthetics result in hypercapnia with depressed heart rate and respiration due to self-breathing, but these values were stable throughout 8 h. Regardless of the mouse condition, brain-wide, robust, and stable BOLD response throughout the somatosensory axis was observed with differences in sensitivity and dynamics. Dexmedetomidine/isoflurane resulted in fast, boxcar-like, BOLD response with consistent hemodynamic shapes throughout the brain. Ketamine/xylazine response showed higher sensitivity, prolonged BOLD response, and evidence for cortical disinhibition as significant bilateral cortical response was observed. In addition, differing hemodynamic shapes were observed between cortical and subcortical areas. Overall, we found both anesthetics are applicable for evoked mouse fMRI studies.
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16
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Somogyi G, Hlatky D, Spisák T, Spisák Z, Nyitrai G, Czurkó A. Deciphering the scopolamine challenge rat model by preclinical functional MRI. Sci Rep 2021; 11:10873. [PMID: 34035328 PMCID: PMC8149883 DOI: 10.1038/s41598-021-90273-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 05/07/2021] [Indexed: 11/09/2022] Open
Abstract
During preclinical drug testing, the systemic administration of scopolamine (SCO), a cholinergic antagonist, is widely used. However, it suffers important limitations, like non-specific behavioural effects partly due to its peripheral side-effects. Therefore, neuroimaging measures would enhance its translational value. To this end, in Wistar rats, we measured whisker-stimulation induced functional MRI activation after SCO, peripherally acting butylscopolamine (BSCO), or saline administration in a cross-over design. Besides the commonly used gradient-echo echo-planar imaging (GE EPI), we also used an arterial spin labeling method in isoflurane anesthesia. With the GE EPI measurement, SCO decreased the evoked BOLD response in the barrel cortex (BC), while BSCO increased it in the anterior cingulate cortex. In a second experiment, we used GE EPI and spin-echo (SE) EPI sequences in a combined (isoflurane + i.p. dexmedetomidine) anesthesia to account for anesthesia-effects. Here, we also examined the effect of donepezil. In the combined anesthesia, with the GE EPI, SCO decreased the activation in the BC and the inferior colliculus (IC). BSCO reduced the response merely in the IC. Our results revealed that SCO attenuated the evoked BOLD activation in the BC as a probable central effect in both experiments. The likely peripheral vascular actions of SCO with the given fMRI sequences depended on the type of anesthesia or its dose.
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Affiliation(s)
- Gergely Somogyi
- Pharmacological and Drug Safety Research, Gedeon Richter Plc., POB: 27, Budapest 10, H-1475 , Hungary
| | - Dávid Hlatky
- Pharmacological and Drug Safety Research, Gedeon Richter Plc., POB: 27, Budapest 10, H-1475 , Hungary
| | - Tamás Spisák
- Pharmacological and Drug Safety Research, Gedeon Richter Plc., POB: 27, Budapest 10, H-1475 , Hungary.,Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
| | - Zsófia Spisák
- Pharmacological and Drug Safety Research, Gedeon Richter Plc., POB: 27, Budapest 10, H-1475 , Hungary
| | - Gabriella Nyitrai
- Pharmacological and Drug Safety Research, Gedeon Richter Plc., POB: 27, Budapest 10, H-1475 , Hungary
| | - András Czurkó
- Pharmacological and Drug Safety Research, Gedeon Richter Plc., POB: 27, Budapest 10, H-1475 , Hungary.
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17
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Wang J, Jing B, Liu R, Li D, Wang W, Wang J, Lei J, Xing Y, Yan J, Loh HH, Lu G, Yang X. Characterizing the seizure onset zone and epileptic network using EEG-fMRI in a rat seizure model. Neuroimage 2021; 237:118133. [PMID: 33951515 DOI: 10.1016/j.neuroimage.2021.118133] [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: 02/20/2021] [Revised: 04/07/2021] [Accepted: 04/26/2021] [Indexed: 11/26/2022] Open
Abstract
Accurate epileptogenic zone (EZ) or seizure onset zone (SOZ) localization is crucial for epilepsy surgery optimization. Previous animal and human studies on epilepsy have reported that changes in blood oxygen level-dependent (BOLD) signals induced by epileptic events could be used as diagnostic markers for EZ or SOZ localization. Simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) recording is gaining interest as a non-invasive tool for preoperative epilepsy evaluation. However, EEG-fMRI studies have reported inconsistent and ambiguous findings. Therefore, it remains unclear whether BOLD responses can be used for accurate EZ or SOZ localization. In this study, we used simultaneous EEG-fMRI recording in a rat model of 4-aminopyridine-induced acute focal seizures to assess the spatial concordance between individual BOLD responses and the SOZ. This was to determine the optimal use of simultaneous EEG-fMRI recording in the SOZ localization. We observed a high spatial consistency between BOLD responses and the SOZ. Further, dynamic BOLD responses were consistent with the regions where the seizures were propagated. These results suggested that simultaneous EEG-fMRI recording could be used as a noninvasive clinical diagnostic technique for localizing the EZ or SOZ and could be an effective tool for mapping epileptic networks.
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Affiliation(s)
- Junling Wang
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China; Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing Institute of Brain Disorders, Beijing, China; Neuroelectrophysiological Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Bin Jing
- School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Ru Liu
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China; Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing Institute of Brain Disorders, Beijing, China; Neuroelectrophysiological Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Donghong Li
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China; Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing Institute of Brain Disorders, Beijing, China; Neuroelectrophysiological Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Wei Wang
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China; Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing Institute of Brain Disorders, Beijing, China; Neuroelectrophysiological Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Jiaoyang Wang
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China; Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing Institute of Brain Disorders, Beijing, China; Neuroelectrophysiological Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Jianfeng Lei
- Core Facilities Center, Capital Medical University, Beijing, China
| | - Yue Xing
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China; Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing Institute of Brain Disorders, Beijing, China; Neuroelectrophysiological Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Jiaqing Yan
- College of Electrical and Control Engineering, North China University of Technology, Beijing, China
| | - Horace H Loh
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Guangming Lu
- Department of Medical Imaging, Jinling Hospital, Southern Medical University, Nanjing, China; Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Xiaofeng Yang
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China; Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing Institute of Brain Disorders, Beijing, China; Neuroelectrophysiological Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China.
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18
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Aksenov DP. Normal Development of Local Neurovascular Interactions and the Diagnostic Value of Resting State Functional MRI in Neurovascular Deficiency Based on the Example of Neonatal Anesthesia Exposure. Front Neurol 2021; 12:664706. [PMID: 33995262 PMCID: PMC8116565 DOI: 10.3389/fneur.2021.664706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/08/2021] [Indexed: 01/25/2023] Open
Affiliation(s)
- Daniil P Aksenov
- Department of Radiology, NorthShore University HealthSystem, Evanston, IL, United States.,Department of Anesthesiology, NorthShore University HealthSystem, Evanston, IL, United States
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19
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Blood oxygen level dependent fMRI and perfusion MRI in the sheep brain. Brain Res 2021; 1760:147390. [PMID: 33631207 DOI: 10.1016/j.brainres.2021.147390] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/15/2021] [Accepted: 02/17/2021] [Indexed: 11/23/2022]
Abstract
The ovine model could be an effective translational model but remains underexplored. Here, Blood Oxygen Level dependent functional MRI during visual stimulation and resting-state perfusion MRI were explored. We aimed at investigating the impact of isoflurane anesthesia during visual stimulation and evaluate resting cerebral blood flow and cerebral blood volume parameters in the lamb and adult sheep brain. BOLD fMRI and perfusion MRI after a bolus of DOTAREM were conducted in 4 lambs and 6 adult ewes at 3 T. A visual stimulation paradigm was delivered during fMRI at increasing isoflurane doses (1-3%). Robust but weak BOLD responses (0.21 ± 0.08%) were found in the lateral geniculate nucleus (LGN) up to 3% isoflurane anaesthesia. No significant differences were found beween BOLD responses in the range 1 to 3% ISO (p > 0.05). However, LGN cluster size decreased and functional localization became less reliable at high ISO doses (2.5-3% ISO). BOLD responses were weaker in adult sheep than in lambs (4.6 ± 1.5 versus 13.6 ± 8.5; p = 0.08). Relative cerebral blood volumes (rCBV) and relative cerebral blood flows (rCBF) were significantly higher (p < 0.0001) in lambs than in adult sheep for both gray and white matter. The impact of volatile anesthesia was explored for the first time on BOLD responses demonstrating increased reliability of functional localization of brain activity at low doses. Perfusion MRI was conducted for the first time in both lambs and adult ewes. Assessment of baseline cerebrovascular values are of interest for future studies of brain diseases allowing an improved interpretation of BOLD responses.
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20
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Barron HC, Mars RB, Dupret D, Lerch JP, Sampaio-Baptista C. Cross-species neuroscience: closing the explanatory gap. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190633. [PMID: 33190601 PMCID: PMC7116399 DOI: 10.1098/rstb.2019.0633] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2020] [Indexed: 12/17/2022] Open
Abstract
Neuroscience has seen substantial development in non-invasive methods available for investigating the living human brain. However, these tools are limited to coarse macroscopic measures of neural activity that aggregate the diverse responses of thousands of cells. To access neural activity at the cellular and circuit level, researchers instead rely on invasive recordings in animals. Recent advances in invasive methods now permit large-scale recording and circuit-level manipulations with exquisite spatio-temporal precision. Yet, there has been limited progress in relating these microcircuit measures to complex cognition and behaviour observed in humans. Contemporary neuroscience thus faces an explanatory gap between macroscopic descriptions of the human brain and microscopic descriptions in animal models. To close the explanatory gap, we propose adopting a cross-species approach. Despite dramatic differences in the size of mammalian brains, this approach is broadly justified by preserved homology. Here, we outline a three-armed approach for effective cross-species investigation that highlights the need to translate different measures of neural activity into a common space. We discuss how a cross-species approach has the potential to transform basic neuroscience while also benefiting neuropsychiatric drug development where clinical translation has, to date, seen minimal success. This article is part of the theme issue 'Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity'.
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Affiliation(s)
- Helen C. Barron
- Medical Research Council Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Rogier B. Mars
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Donders Institute for Brain, Cognition and Behavior, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - David Dupret
- Medical Research Council Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK
| | - Jason P. Lerch
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, CanadaM5G 1L7
| | - Cassandra Sampaio-Baptista
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QB, UK
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21
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Abstract
Renal diseases remain devastating illnesses with unacceptably high rates of mortality and morbidity worldwide. Animal models are essential tools to better understand the pathomechanism of kidney-related illnesses and to develop new, successful therapeutic strategies. Magnetic resonance imaging (MRI) has been actively explored in the last decades for assessing renal function, perfusion, tissue oxygenation as well as the degree of fibrosis and inflammation. This chapter aims to provide an overview of the preparation and monitoring of small animals before, during, and after surgical interventions or MR imaging. Standardization of experimental settings such as body temperature or hydration of animals and minimizing pain and distress are essential for diminishing nonexperimental variables as well as for conducting ethical research.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
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22
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Shim H, Lee J, Kim S. BOLD fMRI and hemodynamic responses to somatosensory stimulation in anesthetized mice: spontaneous breathing vs. mechanical ventilation. NMR IN BIOMEDICINE 2020; 33:e4311. [PMID: 32297409 PMCID: PMC7317444 DOI: 10.1002/nbm.4311] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/26/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
Mouse functional MRI (fMRI) has been of great interest due to the abundance of transgenic models. Due to a mouse's small size, spontaneous breathing has often been used. Because the vascular physiology affecting fMRI might not be controlled normally, its effects on functional responses were investigated with optical intrinsic signal (OIS) imaging and 9.4 T BOLD fMRI. Three conditions were tested in C57BL/6 mice: spontaneous breathing under ketamine and xylazine anesthesia (KX), mechanical ventilation under KX, and mechanical ventilation under isoflurane. Spontaneous breathing under KX induced an average pCO2 of 83 mmHg, whereas a mechanical ventilation condition achieved a pCO2 of 37-41 mmHg within a physiological range. The baseline diameter of arterial and venous vessels was only 7%-9% larger with spontaneous breathing than with mechanical ventilation under KX, but it was much smaller than that in normocapnic isoflurane-anesthetized mice. Three major functional studies were performed. First, CBV-weighted OIS and arterial dilations to 4-second forepaw stimulation were rapid and larger at normocapnia than hypercapnia under KX, but very small under isoflurane. Second, CBV-weighted OIS and arterial dilations by vasodilator acetazolamide were measured for investigating vascular reactivity and were larger in the normocapnic condition than in the hypercapnic condition under KX. Third, evoked OIS and BOLD fMRI responses in the contralateral mouse somatosensory cortex to 20-second forepaw stimulation were faster and larger in the mechanical ventilation than spontaneous breathing. BOLD fMRI peaked at the end of the 20-second stimulation under hypercapnic spontaneous breathing, and at ~9 seconds under mechanical ventilation. The peak amplitude of BOLD fMRI was 2.2% at hypercapnia and ~3.4% at normocapnia. Overall, spontaneous breathing induces sluggish reduced hemodynamic and fMRI responses, but it is still viable for KX anesthesia due to its simplicity, noninvasiveness, and well-localized BOLD activity in the somatosensory cortex.
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Affiliation(s)
- Hyun‐Ji Shim
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Health Sciences and Technology, SAIHSTSungkyunkwan UniversitySeoul06355Republic of Korea
| | - Joonyeol Lee
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Biomedical EngineeringSungkyunkwan UniversitySuwon16419Republic of Korea
| | - Seong‐Gi Kim
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Health Sciences and Technology, SAIHSTSungkyunkwan UniversitySeoul06355Republic of Korea
- Department of Biomedical EngineeringSungkyunkwan UniversitySuwon16419Republic of Korea
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23
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The Pharmacokinetics of Medetomidine Administered Subcutaneously during Isoflurane Anaesthesia in Sprague-Dawley Rats. Animals (Basel) 2020; 10:ani10061050. [PMID: 32570809 PMCID: PMC7341258 DOI: 10.3390/ani10061050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 12/21/2022] Open
Abstract
Anaesthetic protocols involving the combined use of a sedative agent, medetomidine, and an anaesthetic agent, isoflurane, are increasingly being used in functional magnetic resonance imaging (fMRI) studies of the rodent brain. Despite the popularity of this combination, a standardised protocol for the combined use of medetomidine and isoflurane has not been established, resulting in inconsistencies in the reported use of these drugs. This study investigated the pharmacokinetic detail required to standardise the use of medetomidine and isoflurane in rat brain fMRI studies. Using mass spectrometry, serum concentrations of medetomidine were determined in Sprague-Dawley rats during medetomidine and isoflurane anaesthesia. The serum concentration of medetomidine for administration with 0.5% (vapouriser setting) isoflurane was found to be 14.4 ng/mL (±3.0 ng/mL). The data suggests that a steady state serum concentration of medetomidine when administered with 0.5% (vapouriser setting) isoflurane can be achieved with an initial subcutaneous (SC) dose of 0.12 mg/kg of medetomidine followed by a 0.08 mg/kg/h SC infusion of medetomidine. Consideration of these results for future studies will facilitate standardisation of medetomidine and isoflurane anaesthetic protocols during fMRI data acquisition.
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Chen Y, Sobczak F, Pais-Roldán P, Schwarz C, Koretsky AP, Yu X. Mapping the Brain-Wide Network Effects by Optogenetic Activation of the Corpus Callosum. Cereb Cortex 2020; 30:5885-5898. [PMID: 32556241 DOI: 10.1093/cercor/bhaa164] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/25/2020] [Accepted: 05/25/2020] [Indexed: 12/18/2022] Open
Abstract
Optogenetically driven manipulation of circuit-specific activity enables causality studies, but its global brain-wide effect is rarely reported. Here, we applied simultaneous functional magnetic resonance imaging (fMRI) and calcium recording with optogenetic activation of the corpus callosum (CC) connecting barrel cortices (BC). Robust positive BOLD was detected in the ipsilateral BC due to antidromic activity, spreading to the ipsilateral motor cortex (MC), and posterior thalamus (PO). In the orthodromic target, positive BOLD was reliably evoked by 2 Hz light pulses, whereas 40 Hz light pulses led to reduced calcium, indicative of CC-mediated inhibition. This presumed optogenetic CC-mediated inhibition was further elucidated by pairing light pulses with whisker stimulation at varied interstimulus intervals. Whisker-induced positive BOLD and calcium signals were reduced at intervals of 50/100 ms. The calcium-amplitude-modulation-based correlation with whole-brain fMRI signal revealed that the inhibitory effects spread to contralateral BC, ipsilateral MC, and PO. This work raises the need for fMRI to elucidate the brain-wide network activation in response to optogenetic stimulation.
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Affiliation(s)
- Yi Chen
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Baden-Württemberg 72074, Germany
| | - Filip Sobczak
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Baden-Württemberg 72074, Germany
| | - Patricia Pais-Roldán
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Baden-Württemberg 72074, Germany
| | - Cornelius Schwarz
- Werner Reichardt Center for Integrative Neuroscience, Tübingen, Baden-Württemberg 72076, Germany
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Xin Yu
- Research Group of Translational Neuroimaging and Neural Control, High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg 72076, Germany.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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25
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Reimann HM, Niendorf T. The (Un)Conscious Mouse as a Model for Human Brain Functions: Key Principles of Anesthesia and Their Impact on Translational Neuroimaging. Front Syst Neurosci 2020; 14:8. [PMID: 32508601 PMCID: PMC7248373 DOI: 10.3389/fnsys.2020.00008] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 01/27/2020] [Indexed: 12/11/2022] Open
Abstract
In recent years, technical and procedural advances have brought functional magnetic resonance imaging (fMRI) to the field of murine neuroscience. Due to its unique capacity to measure functional activity non-invasively, across the entire brain, fMRI allows for the direct comparison of large-scale murine and human brain functions. This opens an avenue for bidirectional translational strategies to address fundamental questions ranging from neurological disorders to the nature of consciousness. The key challenges of murine fMRI are: (1) to generate and maintain functional brain states that approximate those of calm and relaxed human volunteers, while (2) preserving neurovascular coupling and physiological baseline conditions. Low-dose anesthetic protocols are commonly applied in murine functional brain studies to prevent stress and facilitate a calm and relaxed condition among animals. Yet, current mono-anesthesia has been shown to impair neural transmission and hemodynamic integrity. By linking the current state of murine electrophysiology, Ca2+ imaging and fMRI of anesthetic effects to findings from human studies, this systematic review proposes general principles to design, apply and monitor anesthetic protocols in a more sophisticated way. The further development of balanced multimodal anesthesia, combining two or more drugs with complementary modes of action helps to shape and maintain specific brain states and relevant aspects of murine physiology. Functional connectivity and its dynamic repertoire as assessed by fMRI can be used to make inferences about cortical states and provide additional information about whole-brain functional dynamics. Based on this, a simple and comprehensive functional neurosignature pattern can be determined for use in defining brain states and anesthetic depth in rest and in response to stimuli. Such a signature can be evaluated and shared between labs to indicate the brain state of a mouse during experiments, an important step toward translating findings across species.
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Affiliation(s)
- Henning M. Reimann
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Helmholtz Association of German Research Centers (HZ), Berlin, Germany
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Helmholtz Association of German Research Centers (HZ), Berlin, Germany
- Experimental and Clinical Research Center, A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
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26
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Chen W, Park K, Pan Y, Koretsky AP, Du C. Interactions between stimuli-evoked cortical activity and spontaneous low frequency oscillations measured with neuronal calcium. Neuroimage 2020; 210:116554. [PMID: 31972283 DOI: 10.1016/j.neuroimage.2020.116554] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/07/2019] [Accepted: 01/14/2020] [Indexed: 02/06/2023] Open
Abstract
Spontaneous brain activity has been widely used to map brain connectivity. The interactions between task-evoked brain responses and the spontaneous cortical oscillations, especially within the low frequency range of ~0.1 Hz, are not fully understood. Trial-to-trial variabilities in brain's response to sensory stimuli and the ability for brain to detect under noisy conditions suggest an appreciable impact of the brain state. Using a multimodality imaging platform, we simultaneously imaged neuronal Ca2+ and cerebral hemodynamics at baseline and in response to single-pulse forepaw stimuli in rat's somatosensory cortex. The high sensitivity of this system enables detection of responses to very weak and strong stimuli and real time determination of low frequency oscillations without averaging. Results show that the ongoing neuronal oscillations inversely modulate Ca2+ transients evoked by sensory stimuli. High intensity stimuli reset the spontaneous neuronal oscillations to an unpreferable excitability following the stimulus. Cerebral hemodynamic responses also inversely interact with the spontaneous hemodynamic oscillations, correlating with the neuronal Ca2+ transient changes. The results reveal competing interactions between spontaneous oscillations and stimulation-evoked brain activities in somatosensory cortex and the resultant hemodynamics.
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Affiliation(s)
- Wei Chen
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Kicheon Park
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Yingtian Pan
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Congwu Du
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA.
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Lambers H, Segeroth M, Albers F, Wachsmuth L, van Alst TM, Faber C. A cortical rat hemodynamic response function for improved detection of BOLD activation under common experimental conditions. Neuroimage 2019; 208:116446. [PMID: 31846759 DOI: 10.1016/j.neuroimage.2019.116446] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/13/2019] [Accepted: 12/05/2019] [Indexed: 01/23/2023] Open
Abstract
For a reliable estimation of neuronal activation based on BOLD fMRI measurements an accurate model of the hemodynamic response is essential. Since a large part of basic neuroscience research is based on small animal data, it is necessary to characterize a hemodynamic response function (HRF) which is optimized for small animals. Therefore, we have determined and investigated the HRFs of rats obtained under a variety of experimental conditions in the primary somatosensory cortex. Measurements were performed on animals of different sex and strain, under different anesthetics, with and without ventilation and using different stimulation modalities. All modalities of stimulation used in this study induced neuronal activity in the primary somatosensory cortex or in subcortical regions. Since the HRFs of the BOLD responses in the primary somatosensory cortex showed a close concordance for the different conditions, we were able to determine a cortical rat HRF. This HRF is based on 143 BOLD measurements of 76 rats and can be used for statistical parametric mapping. It showed substantially faster progression than the human HRF, with a maximum after 2.8 ± 0.8 s, and a following undershoot after 6.1 ± 3.7 s. If the rat HRF was used statistical analysis of rat data showed a significantly improved detection performance in the somatosensory cortex in comparison to the commonly used HRF based on measurements in humans.
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Affiliation(s)
- Henriette Lambers
- Translational Research Imaging Center (TRIC), Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Münster, D-48149, Germany
| | - Martin Segeroth
- Translational Research Imaging Center (TRIC), Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Münster, D-48149, Germany
| | - Franziska Albers
- Translational Research Imaging Center (TRIC), Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Münster, D-48149, Germany
| | - Lydia Wachsmuth
- Translational Research Imaging Center (TRIC), Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Münster, D-48149, Germany
| | - Timo Mauritz van Alst
- Translational Research Imaging Center (TRIC), Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Münster, D-48149, Germany
| | - Cornelius Faber
- Translational Research Imaging Center (TRIC), Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Münster, D-48149, Germany.
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28
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Sirmpilatze N, Baudewig J, Boretius S. Temporal stability of fMRI in medetomidine-anesthetized rats. Sci Rep 2019; 9:16673. [PMID: 31723186 PMCID: PMC6853937 DOI: 10.1038/s41598-019-53144-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 10/29/2019] [Indexed: 01/08/2023] Open
Abstract
Medetomidine has become a popular choice for anesthetizing rats during long-lasting sessions of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI). Despite this, it has not yet been thoroughly established how commonly reported fMRI readouts evolve over several hours of medetomidine anesthesia and how they are affected by the precise timing, dose, and route of administration. We used four different protocols of medetomidine administration to anesthetize rats for up to six hours and repeatedly evaluated somatosensory stimulus-evoked BOLD responses and resting state functional connectivity. We found that the temporal evolution of fMRI readouts strongly depended on the method of administration. Intravenous administration of a medetomidine bolus (0.05 mg/kg), combined with a subsequent continuous infusion (0.1 mg/kg/h), led to temporally stable measures of stimulus-evoked activity and functional connectivity throughout the anesthesia. Deviating from the above protocol-by omitting the bolus, lowering the medetomidine dose, or using the subcutaneous route-compromised the stability of these measures in the initial two-hour period. We conclude that both an appropriate protocol of medetomidine administration and a suitable timing of fMRI experiments are crucial for obtaining consistent results. These factors should be considered for the design and interpretation of future rat fMRI studies.
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Affiliation(s)
- Nikoloz Sirmpilatze
- Functional Imaging Laboratory, German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany.
- Georg-August University of Göttingen, Göttingen, Germany.
- International Max Planck Research School for Neurosciences, Göttingen, Germany.
- DFG Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany.
| | - Jürgen Baudewig
- Functional Imaging Laboratory, German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Susann Boretius
- Functional Imaging Laboratory, German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany.
- Georg-August University of Göttingen, Göttingen, Germany.
- International Max Planck Research School for Neurosciences, Göttingen, Germany.
- DFG Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany.
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29
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Just N, Faber C. Probing activation‐induced neurochemical changes using optogenetics combined with functional magnetic resonance spectroscopy: a feasibility study in the rat primary somatosensory cortex. J Neurochem 2019; 150:402-419. [DOI: 10.1111/jnc.14799] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/14/2019] [Accepted: 06/14/2019] [Indexed: 01/22/2023]
Affiliation(s)
- Nathalie Just
- Department of Clinical Radiology University Hospital Münster Münster Germany
| | - Cornelius Faber
- Department of Clinical Radiology University Hospital Münster Münster Germany
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