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Lee HL, Zhou XA, Li Z, Chuang KH. Optimizing diffusion MRI acquisition efficiency of rodent brain using simultaneous multislice EPI. NMR IN BIOMEDICINE 2021; 34:e4398. [PMID: 32839964 DOI: 10.1002/nbm.4398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 06/11/2023]
Abstract
Diffusion tensor imaging (DTI) of the brain provides essential information on the white matter integrity and structural connectivity. However, it suffers from a low signal-to-noise ratio (SNR) and requires a long scan time to achieve high spatial and/or diffusion resolution and wide brain coverage. With recent advances in parallel and simultaneous multislice (multiband) imaging, the SNR efficiency has been improved by reducing the repetition time (TR ). However, due to the limited number of RF coil channels available on preclinical MRI scanners, simultaneous multislice acquisition has not been practical. In this study, we demonstrate the ability of multiband DTI to acquire high-resolution data of the mouse brain with 84 slices covering the whole brain in 0.2 mm isotropic resolution without a coil array at 9.4 T. Hadamard-encoding four-band pulses were used to acquire four slices simultaneously, with the reduction in the TR maximizing the SNR efficiency. To overcome shot-to-shot phase variations, Hadamard decoding with a self-calibrated phase was developed. Compared with single-band DTI acquired with the same scan time, the multiband DTI leads to significantly increased SNR by 40% in the white matter. This SNR gain resulted in reduced variations in fractional anisotropy, mean diffusivity, and eigenvector orientation. Furthermore, the cerebrospinal fluid signal was attenuated, leading to reduced free-water contamination. Without the need for a high-density coil array or parallel imaging, this technique enables highly efficient preclinical DTI that will facilitate connectome studies.
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Affiliation(s)
- Hsu-Lei Lee
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Xiaoqing Alice Zhou
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Zengmin Li
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Kai-Hsiang Chuang
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
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2
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Müller HP, Roselli F, Rasche V, Kassubek J. Diffusion Tensor Imaging-Based Studies at the Group-Level Applied to Animal Models of Neurodegenerative Diseases. Front Neurosci 2020; 14:734. [PMID: 32982659 PMCID: PMC7487414 DOI: 10.3389/fnins.2020.00734] [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: 04/17/2020] [Accepted: 06/22/2020] [Indexed: 12/11/2022] Open
Abstract
The understanding of human and non-human microstructural brain alterations in the course of neurodegenerative diseases has substantially improved by the non-invasive magnetic resonance imaging (MRI) technique of diffusion tensor imaging (DTI). Animal models (including disease or knockout models) allow for a variety of experimental manipulations, which are not applicable to humans. Thus, the DTI approach provides a promising tool for cross-species cross-sectional and longitudinal investigations of the neurobiological targets and mechanisms of neurodegeneration. This overview with a systematic review focuses on the principles of DTI analysis as used in studies at the group level in living preclinical models of neurodegeneration. The translational aspect from in-vivo animal models toward (clinical) applications in humans is covered as well as the DTI-based research of the non-human brains' microstructure, the methodological aspects in data processing and analysis, and data interpretation at different abstraction levels. The aim of integrating DTI in multiparametric or multimodal imaging protocols will allow the interrogation of DTI data in terms of directional flow of information and may identify the microstructural underpinnings of neurodegeneration-related patterns.
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Affiliation(s)
| | - Francesco Roselli
- Department of Neurology, University of Ulm, Ulm, Germany.,German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany
| | - Volker Rasche
- Core Facility Small Animal MRI, University of Ulm, Ulm, Germany
| | - Jan Kassubek
- Department of Neurology, University of Ulm, Ulm, Germany
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3
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Müller HP, Brenner D, Roselli F, Wiesner D, Abaei A, Gorges M, Danzer KM, Ludolph AC, Tsao W, Wong PC, Rasche V, Weishaupt JH, Kassubek J. Longitudinal diffusion tensor magnetic resonance imaging analysis at the cohort level reveals disturbed cortical and callosal microstructure with spared corticospinal tract in the TDP-43 G298S ALS mouse model. Transl Neurodegener 2019; 8:27. [PMID: 31485326 PMCID: PMC6716821 DOI: 10.1186/s40035-019-0163-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 07/16/2019] [Indexed: 12/11/2022] Open
Abstract
Background In vivo diffusion tensor imaging (DTI) of the mouse brain was used to identify TDP-43 associated alterations in a mouse model for amyotrophic lateral sclerosis (ALS). Methods Ten mice with TDP-43 G298S overexpression under control of the Thy1.2 promoter and 10 wild type (wt) underwent longitudinal DTI scans at 11.7 T, including one baseline and one follow-up scan with an interval of about 5 months. Whole brain-based spatial statistics (WBSS) of DTI-based parameter maps was used to identify longitudinal alterations of TDP-43 G298S mice compared to wt at the cohort level. Results were supplemented by tractwise fractional anisotropy statistics (TFAS) and histological evaluation of motor cortex for signs of neuronal loss. Results Alterations at the cohort level in TDP-43 G298S mice were observed cross-sectionally and longitudinally in motor areas M1/M2 and in transcallosal fibers but not in the corticospinal tract. Neuronal loss in layer V of motor cortex was detected in TDP-43 G298S at the later (but not at the earlier) timepoint compared to wt. Conclusion DTI mapping of TDP-43 G298S mice demonstrated progression in motor areas M1/M2. WBSS and TFAS are useful techniques to localize TDP-43 G298S associated alterations over time in this ALS mouse model, as a biological marker.
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Affiliation(s)
- Hans-Peter Müller
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
| | - David Brenner
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
| | - Francesco Roselli
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany.,2German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany
| | - Diana Wiesner
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
| | - Alireza Abaei
- 3Core Facility Small Animal MRI, University of Ulm, Ulm, Germany
| | - Martin Gorges
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
| | - Karin M Danzer
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
| | - Albert C Ludolph
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
| | - William Tsao
- 4Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, USA
| | - Philip C Wong
- 4Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, USA
| | - Volker Rasche
- 3Core Facility Small Animal MRI, University of Ulm, Ulm, Germany
| | - Jochen H Weishaupt
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
| | - Jan Kassubek
- 1Department of Neurology, University of Ulm, Oberer Eselsberg 45, RKU, D-89081 Ulm, Germany
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Salmi M, Bolbos R, Bauer S, Minlebaev M, Burnashev N, Szepetowski P. Transient microstructural brain anomalies and epileptiform discharges in mice defective for epilepsy and language-related NMDA receptor subunit gene Grin2a. Epilepsia 2018; 59:1919-1930. [DOI: 10.1111/epi.14543] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 07/25/2018] [Accepted: 07/25/2018] [Indexed: 12/27/2022]
Affiliation(s)
- Manal Salmi
- INSERM, UMR1249; INMED; Aix-Marseille University; Marseille France
| | | | - Sylvian Bauer
- INSERM, UMR1249; INMED; Aix-Marseille University; Marseille France
| | - Marat Minlebaev
- INSERM, UMR1249; INMED; Aix-Marseille University; Marseille France
- Laboratory of Neurobiology; Kazan Federal University; Kazan Russia
| | - Nail Burnashev
- INSERM, UMR1249; INMED; Aix-Marseille University; Marseille France
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Nouls JC, Badea A, Anderson RB, Cofer GP, Johnson GA. Diffusion tensor imaging using multiple coils for mouse brain connectomics. NMR IN BIOMEDICINE 2018; 31:e3921. [PMID: 29675882 PMCID: PMC5980786 DOI: 10.1002/nbm.3921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 02/15/2018] [Accepted: 02/20/2018] [Indexed: 06/08/2023]
Abstract
The correlation between brain connectivity and psychiatric or neurological diseases has intensified efforts to develop brain connectivity mapping techniques on mouse models of human disease. The neural architecture of mouse brain specimens can be shown non-destructively and three-dimensionally by diffusion tensor imaging, which enables tractography, the establishment of a connectivity matrix and connectomics. However, experiments on cohorts of animals can be prohibitively long. To improve throughput in a 7-T preclinical scanner, we present a novel two-coil system in which each coil is shielded, placed off-isocenter along the axis of the magnet and connected to a receiver circuit of the scanner. Preservation of the quality factor of each coil is essential to signal-to-noise ratio (SNR) performance and throughput, because mouse brain specimen imaging at 7 T takes place in the coil-dominated noise regime. In that regime, we show a shielding configuration causing no SNR degradation in the two-coil system. To acquire data from several coils simultaneously, the coils are placed in the magnet bore, around the isocenter, in which gradient field distortions can bias diffusion tensor imaging metrics, affect tractography and contaminate measurements of the connectivity matrix. We quantified the experimental alterations in fractional anisotropy and eigenvector direction occurring in each coil. We showed that, when the coils were placed 12 mm away from the isocenter, measurements of the brain connectivity matrix appeared to be minimally altered by gradient field distortions. Simultaneous measurements on two mouse brain specimens demonstrated a full doubling of the diffusion tensor imaging throughput in practice. Each coil produced images devoid of shading or artifact. To further improve the throughput of mouse brain connectomics, we suggested a future expansion of the system to four coils. To better understand acceptable trade-offs between imaging throughput and connectivity matrix integrity, studies may seek to clarify how measurement variability, post-processing techniques and biological variability impact mouse brain connectomics.
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Affiliation(s)
- John C. Nouls
- Center for In Vivo Microscopy, Radiology, Duke University Medical Center, Durham, NC, USA
- Radiology, Duke University, Durham, NC, USA
| | - Alexandra Badea
- Center for In Vivo Microscopy, Radiology, Duke University Medical Center, Durham, NC, USA
- Radiology, Duke University, Durham, NC, USA
| | - Robert B.J. Anderson
- Center for In Vivo Microscopy, Radiology, Duke University Medical Center, Durham, NC, USA
- Radiology, Duke University, Durham, NC, USA
| | - Gary P. Cofer
- Center for In Vivo Microscopy, Radiology, Duke University Medical Center, Durham, NC, USA
- Radiology, Duke University, Durham, NC, USA
| | - G. Allan Johnson
- Center for In Vivo Microscopy, Radiology, Duke University Medical Center, Durham, NC, USA
- Radiology, Duke University, Durham, NC, USA
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6
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Snow WM, Dale R, O'Brien-Moran Z, Buist R, Peirson D, Martin M, Albensi BC. In Vivo Detection of Gray Matter Neuropathology in the 3xTg Mouse Model of Alzheimer's Disease with Diffusion Tensor Imaging. J Alzheimers Dis 2018; 58:841-853. [PMID: 28505976 DOI: 10.3233/jad-170136] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A diagnosis of Alzheimer's disease (AD), a neurodegenerative disorder accompanied by severe functional and cognitive decline, is based on clinical findings, with final confirmation of the disease at autopsy by the presence of amyloid-β (Aβ) plaques and neurofibrillary tangles. Given that microstructural brain alterations occur years prior to clinical symptoms, efforts to detect brain changes early could significantly enhance our ability to diagnose AD sooner. Diffusion tensor imaging (DTI), a type of MRI that characterizes the magnitude, orientation, and anisotropy of the diffusion of water in tissues, has been used to infer neuropathological changes in vivo. Its utility in AD, however, is still under investigation. The current study used DTI to examine brain regions susceptible to AD-related pathology; the cerebral cortex, entorhinal cortex, and hippocampus, in 12-14-month-old 3xTg AD mice that possess both Aβ plaques and neurofibrillary tangles. Mean diffusivity did not differ between 3xTg and control mice in any region. Decreased fractional anisotropy (p < 0.01) and axial diffusivity (p < 0.05) were detected only in the hippocampus, in which both congophilic Aβ plaques and hyperphosphorylated tau accumulation, consistent with neurofibrillary tangle formation, were detected. Pathological tau accumulation was seen in the cortex. The entorhinal cortex was largely spared from AD-related neuropathology. This is the first study to demonstrate DTI abnormalities in gray matter in a mouse model of AD in which both pathological hallmarks are present, suggesting the feasibility of DTI as a non-invasive means of detecting brain pathology in vivo in early-stage AD.
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Affiliation(s)
- Wanda M Snow
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada.,Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Ryan Dale
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada.,Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | | | - Richard Buist
- Department of Radiology, University of Manitoba, Winnipeg, MB, Canada
| | - Danial Peirson
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada.,Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Melanie Martin
- Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, MB, Canada.,Department of Physics, University of Winnipeg, Winnipeg, MB, Canada.,Department of Radiology, University of Manitoba, Winnipeg, MB, Canada
| | - Benedict C Albensi
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada.,Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, MB, Canada
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Gorges M, Roselli F, Müller HP, Ludolph AC, Rasche V, Kassubek J. Functional Connectivity Mapping in the Animal Model: Principles and Applications of Resting-State fMRI. Front Neurol 2017; 8:200. [PMID: 28539914 PMCID: PMC5423907 DOI: 10.3389/fneur.2017.00200] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 04/24/2017] [Indexed: 12/25/2022] Open
Abstract
"Resting-state" fMRI has substantially contributed to the understanding of human and non-human functional brain organization by the analysis of correlated patterns in spontaneous activity within dedicated brain systems. Spontaneous neural activity is indirectly measured from the blood oxygenation level-dependent signal as acquired by echo planar imaging, when subjects quietly "resting" in the scanner. Animal models including disease or knockout models allow a broad spectrum of experimental manipulations not applicable in humans. The non-invasive fMRI approach provides a promising tool for cross-species comparative investigations. This review focuses on the principles of "resting-state" functional connectivity analysis and its applications to living animals. The translational aspect from in vivo animal models toward clinical applications in humans is emphasized. We introduce the fMRI-based investigation of the non-human brain's hemodynamics, the methodological issues in the data postprocessing, and the functional data interpretation from different abstraction levels. The longer term goal of integrating fMRI connectivity data with structural connectomes obtained with tracing and optical imaging approaches is presented and will allow the interrogation of fMRI data in terms of directional flow of information and may identify the structural underpinnings of observed functional connectivity patterns.
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Affiliation(s)
- Martin Gorges
- Department of Neurology, University of Ulm, Ulm, Germany
| | - Francesco Roselli
- Department of Neurology, University of Ulm, Ulm, Germany
- Department of Anatomy and Cell Biology, University of Ulm, Ulm, Germany
| | | | | | - Volker Rasche
- Core Facility Small Animal MRI, University of Ulm, Ulm, Germany
| | - Jan Kassubek
- Department of Neurology, University of Ulm, Ulm, Germany
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8
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Alomair OI, Brereton IM, Smith MT, Galloway GJ, Kurniawan ND. In vivo high angular resolution diffusion-weighted imaging of mouse brain at 16.4 Tesla. PLoS One 2015; 10:e0130133. [PMID: 26110770 PMCID: PMC4482319 DOI: 10.1371/journal.pone.0130133] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 05/18/2015] [Indexed: 11/19/2022] Open
Abstract
Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T1 and shorter T2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM) diseases.
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Affiliation(s)
- Othman I. Alomair
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
- College of Applied Medical Science, King Saud University, Riyadh, Saudi Arabia
| | - Ian M. Brereton
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
| | - Maree T. Smith
- School of Pharmacy, University of Queensland, Brisbane, Queensland, Australia
| | - Graham J. Galloway
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
| | - Nyoman D. Kurniawan
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
- * E-mail:
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9
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Keifer OP, Gutman DA, Hecht EE, Keilholz SD, Ressler KJ. A comparative analysis of mouse and human medial geniculate nucleus connectivity: a DTI and anterograde tracing study. Neuroimage 2014; 105:53-66. [PMID: 25450110 DOI: 10.1016/j.neuroimage.2014.10.047] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 10/16/2014] [Accepted: 10/19/2014] [Indexed: 01/16/2023] Open
Abstract
Understanding the function and connectivity of thalamic nuclei is critical for understanding normal and pathological brain function. The medial geniculate nucleus (MGN) has been studied mostly in the context of auditory processing and its connection to the auditory cortex. However, there is a growing body of evidence that the MGN and surrounding associated areas ('MGN/S') have a diversity of projections including those to the globus pallidus, caudate/putamen, amygdala, hypothalamus, and thalamus. Concomitantly, pathways projecting to the medial geniculate include not only the inferior colliculus but also the auditory cortex, insula, cerebellum, and globus pallidus. Here we expand our understanding of the connectivity of the MGN/S by using comparative diffusion weighted imaging with probabilistic tractography in both human and mouse brains (most previous work was in rats). In doing so, we provide the first report that attempts to match probabilistic tractography results between human and mice. Additionally, we provide anterograde tracing results for the mouse brain, which corroborate the probabilistic tractography findings. Overall, the study provides evidence for the homology of MGN/S patterns of connectivity across species for understanding translational approaches to thalamic connectivity and function. Further, it points to the utility of DTI in both human studies and small animal modeling, and it suggests potential roles of these connections in human cognition, behavior, and disease.
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Affiliation(s)
- Orion P Keifer
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA; Yerkes National Primate Research Center, Atlanta, GA, USA
| | - David A Gutman
- Department of Biomedical Informatics, Emory University, Atlanta, GA, USA
| | - Erin E Hecht
- Department of Anthropology, Emory University, Atlanta, GA, USA
| | - Shella D Keilholz
- Coulter Department of Biomedical Engineering, Emory University/Georgia Institute of Technology, Atlanta, GA, USA
| | - Kerry J Ressler
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA; Yerkes National Primate Research Center, Atlanta, GA, USA.
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10
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Taveira TH, Wu WC, Tschibelu E, Borsook D, Simonson DC, Yamamoto R, Langleben DD, Swift R, Elman I. The effect of naltrexone on body fat mass in olanzapine-treated schizophrenic or schizoaffective patients: a randomized double-blind placebo-controlled pilot study. J Psychopharmacol 2014; 28:395-400. [PMID: 24218048 DOI: 10.1177/0269881113509904] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Olanzapine (OLZ), a commonly prescribed second generation antipsychotic drug, is associated with obesity and metabolic syndrome and may contribute to increased cardiovascular morbidity and mortality. Opioidergic neurotransmission may be implicated in the development of these metabolic disturbances. The objective of this study was to assess the effects of opioid blockade on OLZ-treated patients' metabolic status. Patients with schizophrenia or schizoaffective disorder (n=30) on a stable dose of OLZ were randomized in a double-blind fashion to receive an opioid receptor antagonist, naltrexone (NTX), (n=14) or placebo (n=16). The primary outcome measure was the change in body mass index (BMI) at 12 weeks. Secondary measures included body fat and fat-free mass, along with homeostasis model assessment-estimated insulin resistance (HOMA-IR), plasma lipids and liver function tests (LFTs). There was no significant change in BMI between the treatment arms. However, in comparison to the OLZ + placebo combination, the OLZ + NTX group displayed a significant decrease in the fat and increase in fat-free mass along with a trend towards improvement in HOMA-IR values. There were no significant differences in plasma lipids and LFTs. These findings suggest that addition of NTX to OLZ may attenuate OLZ-induced body fat mass gain. A larger study of longer duration will be needed to confirm these results.
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11
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Müller HP, Kassubek J, Vernikouskaya I, Ludolph AC, Stiller D, Rasche V. Diffusion tensor magnetic resonance imaging of the brain in APP transgenic mice: a cohort study. PLoS One 2013; 8:e67630. [PMID: 23840754 PMCID: PMC3695895 DOI: 10.1371/journal.pone.0067630] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/20/2013] [Indexed: 12/11/2022] Open
Abstract
INTRODUCTION Fast in-vivo high resolution diffusion tensor imaging (DTI) of the mouse brain has recently been shown to enable cohort studies by the combination of appropriate pulse sequences and cryogenically cooled resonators (CCR). The objective of this study was to apply this DTI approach at the group level to β-amyloid precursor protein (APP) transgenic mice. METHODS Twelve mice (5 wild type, 7 APP transgenic tg2576) underwent DTI examination at 156(2) × 250 µm(3) spatial resolution with a CCR at ultrahigh field (11.7 T). Diffusion images were acquired along 30 gradient directions plus 5 references without diffusion encoding with a total acquisition time of 35 minutes. Fractional anisotropy (FA) maps were statistically compared by whole brain-based spatial statistics (WBSS) at the group level vs. wild type controls. RESULTS FA-map comparison showed characteristic regional patterns of differences between the groups with localizations associated with Alzheimer's disease in humans, such as the hippocampus, the entorhinal cortex, and the caudoputamen. CONCLUSION In this proof-of-principle study, regions associated with amyloid-β deposition could be identified by WBSS of FA maps in APP transgenic mice vs. wild type mice. Thus, DTI in the mouse brain acquired at 11.7 T by use of a CCR was demonstrated to be feasible for cohort studies.
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12
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In vivo high-resolution diffusion tensor imaging of the mouse brain. Neuroimage 2013; 83:18-26. [PMID: 23769916 DOI: 10.1016/j.neuroimage.2013.06.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 06/04/2013] [Accepted: 06/05/2013] [Indexed: 01/21/2023] Open
Abstract
Diffusion tensor imaging (DTI) of the laboratory mouse brain provides important macroscopic information for anatomical characterization of mouse models in basic research. Currently, in vivo DTI of the mouse brain is often limited by the available resolution. In this study, we demonstrate in vivo high-resolution DTI of the mouse brain using a cryogenic probe and a modified diffusion-weighted gradient and spin echo (GRASE) imaging sequence at 11.7 T. Three-dimensional (3D) DTI of the entire mouse brain at 0.125 mm isotropic resolution could be obtained in approximately 2 h. The high spatial resolution, which was previously only available with ex vivo imaging, enabled non-invasive examination of small structures in the adult and neonatal mouse brains. Based on data acquired from eight adult mice, a group-averaged DTI atlas of the in vivo adult mouse brain with 60 structure segmentations was developed. Comparisons between in vivo and ex vivo mouse brain DTI data showed significant differences in brain morphology and tissue contrasts, which indicate the importance of the in vivo DTI-based mouse brain atlas.
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