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Maharjan S, Tsai AP, Lin PB, Ingraham C, Jewett MR, Landreth GE, Oblak AL, Wang N. Age-dependent microstructure alterations in 5xFAD mice by high-resolution diffusion tensor imaging. Front Neurosci 2022; 16:964654. [PMID: 36061588 PMCID: PMC9428354 DOI: 10.3389/fnins.2022.964654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/18/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose To evaluate the age-dependent microstructure changes in 5xFAD mice using high-resolution diffusion tensor imaging (DTI). Methods The 5xFAD mice at 4, 7.5, and 12 months and the wild-type controls at 4 months were scanned at 9.4T using a 3D echo-planar imaging (EPI) pulse sequence with the isotropic spatial resolution of 100 μm. The b-value was 3000 s/mm2 for all the diffusion MRI scans. The samples were also acquired with a gradient echo pulse sequence at 50 μm isotropic resolution. The microstructure changes were quantified with DTI metrics, including fractional anisotropy (FA) and mean diffusivity (MD). The conventional histology was performed to validate with MRI findings. Results The FA values (p = 0.028) showed significant differences in the cortex between wild-type (WT) and 5xFAD mice at 4 months, while hippocampus, anterior commissure, corpus callosum, and fornix showed no significant differences for either FA and MD. FA values of 5xFAD mice gradually decreased in cortex (0.140 ± 0.007 at 4 months, 0.132 ± 0.008 at 7.5 months, 0.126 ± 0.013 at 12 months) and fornix (0.140 ± 0.007 at 4 months, 0.132 ± 0.008 at 7.5 months, 0.126 ± 0.013 at 12 months) with aging. Both FA (p = 0.029) and MD (p = 0.037) demonstrated significant differences in corpus callosum between 4 and 12 months age old. FA and MD were not significantly different in the hippocampus or anterior commissure. The age-dependent microstructure alterations were better captured by FA when compared to MD. Conclusion FA showed higher sensitivity to monitor amyloid deposition in 5xFAD mice. DTI may be utilized as a sensitive biomarker to monitor beta-amyloid progression for preclinical studies.
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Affiliation(s)
- Surendra Maharjan
- Department of Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, United States
| | - Andy P. Tsai
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, United States
| | - Peter B. Lin
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, United States
| | - Cynthia Ingraham
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, United States
| | - Megan R. Jewett
- Department of Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, United States
| | - Gary E. Landreth
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, United States
- Department of Anatomy, Cell Biology and Physiology, Indiana University, Indianapolis, IN, United States
| | - Adrian L. Oblak
- Department of Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, United States
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, United States
| | - Nian Wang
- Department of Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, United States
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, United States
- *Correspondence: Nian Wang,
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2
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Ni R. Magnetic Resonance Imaging in Animal Models of Alzheimer's Disease Amyloidosis. Int J Mol Sci 2021; 22:12768. [PMID: 34884573 PMCID: PMC8657987 DOI: 10.3390/ijms222312768] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/18/2021] [Accepted: 11/23/2021] [Indexed: 02/07/2023] Open
Abstract
Amyloid-beta (Aβ) plays an important role in the pathogenesis of Alzheimer's disease. Aberrant Aβ accumulation induces neuroinflammation, cerebrovascular alterations, and synaptic deficits, leading to cognitive impairment. Animal models recapitulating the Aβ pathology, such as transgenic, knock-in mouse and rat models, have facilitated the understanding of disease mechanisms and the development of therapeutics targeting Aβ. There is a rapid advance in high-field MRI in small animals. Versatile high-field magnetic resonance imaging (MRI) sequences, such as diffusion tensor imaging, arterial spin labeling, resting-state functional MRI, anatomical MRI, and MR spectroscopy, as well as contrast agents, have been developed for preclinical imaging in animal models. These tools have enabled high-resolution in vivo structural, functional, and molecular readouts with a whole-brain field of view. MRI has been used to visualize non-invasively the Aβ deposits, synaptic deficits, regional brain atrophy, impairment in white matter integrity, functional connectivity, and cerebrovascular and glymphatic system in animal models of Alzheimer's disease amyloidosis. Many of the readouts are translational toward clinical MRI applications in patients with Alzheimer's disease. In this review, we summarize the recent advances in MRI for visualizing the pathophysiology in amyloidosis animal models. We discuss the outstanding challenges in brain imaging using MRI in small animals and propose future outlook in visualizing Aβ-related alterations in the brains of animal models.
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Affiliation(s)
- Ruiqing Ni
- Institute for Biomedical Engineering, ETH Zurich & University of Zurich, 8093 Zurich, Switzerland;
- Institute for Regenerative Medicine, University of Zurich, 8952 Zurich, Switzerland
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3
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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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4
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Multiple inflammatory profiles of microglia and altered neuroimages in APP/PS1 transgenic AD mice. Brain Res Bull 2020; 156:86-104. [DOI: 10.1016/j.brainresbull.2020.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/14/2019] [Accepted: 01/03/2020] [Indexed: 12/11/2022]
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5
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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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Colon-Perez LM, Ibanez KR, Suarez M, Torroella K, Acuna K, Ofori E, Levites Y, Vaillancourt DE, Golde TE, Chakrabarty P, Febo M. Neurite orientation dispersion and density imaging reveals white matter and hippocampal microstructure changes produced by Interleukin-6 in the TgCRND8 mouse model of amyloidosis. Neuroimage 2019; 202:116138. [PMID: 31472250 DOI: 10.1016/j.neuroimage.2019.116138] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 08/15/2019] [Accepted: 08/27/2019] [Indexed: 02/07/2023] Open
Abstract
Extracellular β-amyloid (Aβ) plaque deposits and inflammatory immune activation are thought to alter various aspects of tissue microstructure, such as extracellular free water, fractional anisotropy and diffusivity, as well as the density and geometric arrangement of axonal processes. Quantifying these microstructural changes in Alzheimer's disease and related neurodegenerative dementias could serve to monitor or predict disease course. In the present study we used high-field diffusion magnetic resonance imaging (dMRI) to investigate the effects of Aβ and inflammatory interleukin-6 (IL6), alone or in combination, on in vivo tissue microstructure in the TgCRND8 mouse model of Alzheimer's-type Aβ deposition. TgCRND8 and non-transgenic (nTg) mice expressing brain-targeted IL6 or enhanced glial fibrillary protein (EGFP controls) were scanned at 8 months of age using a 2-shell, 54-gradient direction dMRI sequence at 11.1 T. Images were processed using the diffusion tensor imaging (DTI) model or the neurite orientation dispersion and density imaging (NODDI) model. DTI and NODDI processing in TgCRND8 mice revealed a microstructure pattern in white matter (WM) and hippocampus consistent with radial and longitudinal diffusivity deficits along with an increase in density and geometric complexity of axonal and dendritic processes. This included reduced FA, mean, axial and radial diffusivity, and increased orientation dispersion (ODI) and intracellular volume fraction (ICVF) measured in WM and hippocampus. IL6 produced a 'protective-like' effect on WM FA in TgCRND8 mice, observed as an increased FA that counteracted a reduction in FA observed with endogenous Aβ production and accumulation. In addition, we found that ICVF and ODI had an inverse relationship with the functional connectome clustering coefficient. The relationship between NODDI and graph theory metrics suggests that currently unknown microstructure alterations in WM and hippocampus are associated with diminished functional network organization in the brain.
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Affiliation(s)
- Luis M Colon-Perez
- Florida Alzheimer's Disease Research Center, University of Florida, Gainesville, United States; Department of Psychiatry, University of Florida, Gainesville, United States
| | - Kristen R Ibanez
- Center for Translational Research on Neurodegenerative Diseases, University of Florida, Gainesville, United States; Department of Neuroscience, University of Florida, Gainesville, United States
| | - Mallory Suarez
- Department of Psychiatry, University of Florida, Gainesville, United States
| | - Kristin Torroella
- Department of Psychiatry, University of Florida, Gainesville, United States
| | - Kelly Acuna
- Department of Psychiatry, University of Florida, Gainesville, United States
| | - Edward Ofori
- Florida Alzheimer's Disease Research Center, University of Florida, Gainesville, United States; Applied Physiology & Kinesiology, University of Florida, Gainesville, United States
| | - Yona Levites
- Florida Alzheimer's Disease Research Center, University of Florida, Gainesville, United States; Center for Translational Research on Neurodegenerative Diseases, University of Florida, Gainesville, United States; Department of Neuroscience, University of Florida, Gainesville, United States; McKnight Brain Institute, University of Florida, Gainesville, United States
| | - David E Vaillancourt
- Florida Alzheimer's Disease Research Center, University of Florida, Gainesville, United States; Advanced Magnetic Resonance Imaging and Spectroscopy Facility, University of Florida, Gainesville, United States; Department of Psychiatry, University of Florida, Gainesville, United States; Applied Physiology & Kinesiology, University of Florida, Gainesville, United States
| | - Todd E Golde
- Florida Alzheimer's Disease Research Center, University of Florida, Gainesville, United States; Center for Translational Research on Neurodegenerative Diseases, University of Florida, Gainesville, United States; Department of Neuroscience, University of Florida, Gainesville, United States; McKnight Brain Institute, University of Florida, Gainesville, United States
| | - Paramita Chakrabarty
- Florida Alzheimer's Disease Research Center, University of Florida, Gainesville, United States; Center for Translational Research on Neurodegenerative Diseases, University of Florida, Gainesville, United States; Department of Neuroscience, University of Florida, Gainesville, United States; McKnight Brain Institute, University of Florida, Gainesville, United States.
| | - Marcelo Febo
- Florida Alzheimer's Disease Research Center, University of Florida, Gainesville, United States; Advanced Magnetic Resonance Imaging and Spectroscopy Facility, University of Florida, Gainesville, United States; Department of Psychiatry, University of Florida, Gainesville, United States; McKnight Brain Institute, University of Florida, Gainesville, United States.
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7
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Gorges M, Müller HP, Liepelt-Scarfone I, Storch A, Dodel R, Hilker-Roggendorf R, Berg D, Kunz MS, Kalbe E, Baudrexel S, Kassubek J. Structural brain signature of cognitive decline in Parkinson's disease: DTI-based evidence from the LANDSCAPE study. Ther Adv Neurol Disord 2019; 12:1756286419843447. [PMID: 31205489 PMCID: PMC6535714 DOI: 10.1177/1756286419843447] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 03/19/2019] [Indexed: 12/12/2022] Open
Abstract
Background: The nonmotor symptom spectrum of Parkinson’s disease (PD) includes progressive cognitive decline mainly in late stages of the disease. The aim of this study was to map the patterns of altered structural connectivity of patients with PD with different cognitive profiles ranging from cognitively unimpaired to PD-associated dementia. Methods: Diffusion tensor imaging and neuropsychological data from the observational multicentre LANDSCAPE study were analyzed. A total of 134 patients with PD with normal cognitive function (56 PD-N), mild cognitive impairment (67 PD-MCI), and dementia (11 PD-D) as well as 72 healthy controls were subjected to whole-brain-based fractional anisotropy mapping and covariance analysis with cognitive performance measures. Results: Structural data indicated subtle changes in the corpus callosum and thalamic radiation in PD-N, whereas severe white matter impairment was observed in both PD-MCI and PD-D patients including anterior and inferior fronto-occipital, uncinate, insular cortices, superior longitudinal fasciculi, corona radiata, and the body of the corpus callosum. These regional alterations were demonstrated for PD-MCI and were more pronounced in PD-D. The pattern of involved regions was significantly correlated with the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) total score. Conclusions: The findings in PD-N suggest impaired cross-hemispherical white matter connectivity that can apparently be compensated for. More pronounced involvement of the corpus callosum as demonstrated for PD-MCI together with affection of fronto-parieto-temporal structural connectivity seems to lead to gradual disruption of cognition-related cortico-cortical networks and to be associated with the onset of overt cognitive deficits. The increase of regional white matter damage appears to be associated with the development of PD-associated dementia.
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Affiliation(s)
- Martin Gorges
- Department of Neurology, University of Ulm, Ulm, Germany
| | | | - Inga Liepelt-Scarfone
- German Center of Neurodegenerative Diseases and Hertie Institute for Clinical Brain Research, Tübingen, Germany
| | - Alexander Storch
- Department of Neurology, University of Rostock, Rostock, Germany
| | - Richard Dodel
- Department of Neurology, Philipps University Marburg, Marburg, Germany
| | | | - Rüdiger Hilker-Roggendorf
- Klinik für Neurologie und Klinische Neurophysiologie, Klinikum Vest, Knappschaftskrankenhaus Recklinghausen, Recklinghausen, Germany
| | - Daniela Berg
- German Center of Neurodegenerative Diseases and Hertie Institute for Clinical Brain Research, Tübingen, Germany
| | - Martin S Kunz
- Department of Neurology, University of Ulm, Ulm, Germany
| | - Elke Kalbe
- Medical Psychology
- Neuropsychology and Gender Studies, Center for Neuropsychological Diagnostics and Intervention (CeNDI), University Hospital Cologne, Cologne, Germany
| | - Simon Baudrexel
- Department of Neurology, J.W. Goethe University, Frankfurt/Main, Germany
| | - Jan Kassubek
- Department of Neurology, University of Ulm, RKU, Oberer Eselsberg 45, Ulm 89081, Germany
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8
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Abe Y, Komaki Y, Seki F, Shibata S, Okano H, Tanaka KF. Correlative study using structural MRI and super-resolution microscopy to detect structural alterations induced by long-term optogenetic stimulation of striatal medium spiny neurons. Neurochem Int 2019; 125:163-174. [PMID: 30825601 DOI: 10.1016/j.neuint.2019.02.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 11/27/2022]
Abstract
Striatal medium spiny neurons (MSNs) control motor function. Hyper- or hypo-activity of MSNs coincides with basal ganglia-related movement disorders. Based on the assumption that lasting alterations in neuronal activity lead to structural changes in the brain, understanding these structural alterations may be used to infer MSN functional abnormalities. To infer MSN function from structural data, understanding how long-lasting alterations in MSN activity affect brain morphology is essential. To address this, we utilized a simplified model of functional induction by stimulating MSNs expressing channelrhodopsin 2 (ChR2). Subsequent structural alterations which induced long-term activity changes in these MSNs were investigated in the striatal pathway and its associated regions by diffusion tensor imaging (DTI) and histological assessment with super-resolution microscopy. DTI detected changes in the striatum, substantia nigra, and motor cortex. Histological assessment found a reduction in the diameter of myelinated cortical axons as well as MSN dendrites and axons. The structural changes showed a high correlation between DTI parameters and histological data. These results demonstrated that long-term neural activation in the MSNs alters the diameter of MSN and cortical neurons fibers. This study provides a tool for understanding the causal relationship between functional and structural alterations.
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Affiliation(s)
- Yoshifumi Abe
- Department of Neuropsychiatry, Keio University School of Medicine, Japan.
| | - Yuji Komaki
- Department of Physiology, Keio University School of Medicine, Japan; Live Imaging Center, Central Institute for Experimental Animals, Japan
| | - Fumiko Seki
- Department of Physiology, Keio University School of Medicine, Japan; Live Imaging Center, Central Institute for Experimental Animals, Japan
| | - Shinsuke Shibata
- Department of Physiology, Keio University School of Medicine, Japan; Electron Microscope Laboratory, Keio University School of Medicine, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Japan; Electron Microscope Laboratory, Keio University School of Medicine, Japan; Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science, Japan
| | - Kenji F Tanaka
- Department of Neuropsychiatry, Keio University School of Medicine, Japan
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9
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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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10
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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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11
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Barlow RL, Gorges M, Wearn A, Niessen HG, Kassubek J, Dalley JW, Pekcec A. Ventral Striatal D2/3 Receptor Availability Is Associated with Impulsive Choice Behavior As Well As Limbic Corticostriatal Connectivity. Int J Neuropsychopharmacol 2018; 21:705-715. [PMID: 29554302 PMCID: PMC6030945 DOI: 10.1093/ijnp/pyy030] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/14/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Low dopamine D2/3 receptor availability in the nucleus accumbens shell is associated with highly impulsive behavior in rats as measured by premature responses in a cued attentional task. However, it is unclear whether dopamine D2/3 receptor availability in the nucleus accumbens is equally linked to intolerance for delayed rewards, a related form of impulsivity. METHODS We investigated the relationship between D2/3 receptor availability in the nucleus accumbens and impulsivity in a delay-discounting task where animals must choose between immediate, small-magnitude rewards and delayed, larger-magnitude rewards. Corticostriatal D2/3 receptor availability was measured in rats stratified for high and low impulsivity using in vivo [18F]fallypride positron emission tomography and ex vivo [3H]raclopride autoradiography. Resting-state functional connectivity in limbic corticostriatal networks was also assessed using fMRI. RESULTS Delay-discounting task impulsivity was inversely related to D2/3 receptor availability in the nucleus accumbens core but not the dorsal striatum, with higher D2/3 binding in the nucleus accumbens shell of high-impulsive rats compared with low-impulsive rats. D2/3 receptor availability was associated with stronger connectivity between the cingulate cortex and hippocampus of high- vs low-impulsive rats. CONCLUSIONS We conclude that delay-discounting task impulsivity is associated with low D2/3 receptor binding in the nucleus accumbens core. Thus, two related forms of waiting impulsivity-premature responding and delay intolerance in a delay-of-reward task-implicate an involvement of D2/3 receptor availability in the nucleus accumbens shell and core, respectively. This dissociation may be causal or consequential to enhanced functional connectivity of limbic brain circuitry and hold relevance for attention-deficit/hyperactivity disorder, drug addiction, and other psychiatric disorders.
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Affiliation(s)
- Rebecca L Barlow
- Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Discovery Research, Biberach an der Riss, Germany
| | - Martin Gorges
- Department of Neurology, University of Ulm, RKU, Ulm, Germany
| | - Alfie Wearn
- Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Discovery Research, Biberach an der Riss, Germany
| | - Heiko G Niessen
- Boehringer Ingelheim Pharma GmbH & Co. KG, Translational Medicine & Clinical Pharmacology, Biberach an der Riss, Germany
| | - Jan Kassubek
- Department of Neurology, University of Ulm, RKU, Ulm, Germany
| | - Jeffrey W Dalley
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom,Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom
| | - Anton Pekcec
- Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Discovery Research, Biberach an der Riss, Germany,Correspondence: Anton Pekcec, DVM, PhD, Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Discovery Research, Birkendorfer Strasse 65, 88397, Biberach an der Riss, Germany ()
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12
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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: 58] [Impact Index Per Article: 8.3] [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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13
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Badea A, Kane L, Anderson RJ, Qi Y, Foster M, Cofer GP, Medvitz N, Buckley AF, Badea AK, Wetsel WC, Colton CA. The fornix provides multiple biomarkers to characterize circuit disruption in a mouse model of Alzheimer's disease. Neuroimage 2016; 142:498-511. [PMID: 27521741 DOI: 10.1016/j.neuroimage.2016.08.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/23/2016] [Accepted: 08/09/2016] [Indexed: 12/19/2022] Open
Abstract
Multivariate biomarkers are needed for detecting Alzheimer's disease (AD), understanding its etiology, and quantifying the effect of therapies. Mouse models provide opportunities to study characteristics of AD in well-controlled environments that can help facilitate development of early interventions. The CVN-AD mouse model replicates multiple AD hallmark pathologies, and we identified multivariate biomarkers characterizing a brain circuit disruption predictive of cognitive decline. In vivo and ex vivo magnetic resonance imaging (MRI) revealed that CVN-AD mice replicate the hippocampal atrophy (6%), characteristic of humans with AD, and also present changes in subcortical areas. The largest effect was in the fornix (23% smaller), which connects the septum, hippocampus, and hypothalamus. In characterizing the fornix with diffusion tensor imaging, fractional anisotropy was most sensitive (20% reduction), followed by radial (15%) and axial diffusivity (2%), in detecting pathological changes. These findings were strengthened by optical microscopy and ultrastructural analyses. Ultrastructual analysis provided estimates of axonal density, diameters, and myelination-through the g-ratio, defined as the ratio between the axonal diameter, and the diameter of the axon plus the myelin sheath. The fornix had reduced axonal density (47% fewer), axonal degeneration (13% larger axons), and abnormal myelination (1.5% smaller g-ratios). CD68 staining showed that white matter pathology could be secondary to neuronal degeneration, or due to direct microglial attack. In conclusion, these findings strengthen the hypothesis that the fornix plays a role in AD, and can be used as a disease biomarker and as a target for therapy.
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Affiliation(s)
- Alexandra Badea
- Center for In Vivo Microscopy, Duke University Medical Center, Department of Radiology, Durham, NC 27710, USA.
| | - Lauren Kane
- Trinity College of Arts & Sciences, Duke University, Durham, NC 27710, USA
| | - Robert J Anderson
- Center for In Vivo Microscopy, Duke University Medical Center, Department of Radiology, Durham, NC 27710, USA
| | - Yi Qi
- Center for In Vivo Microscopy, Duke University Medical Center, Department of Radiology, Durham, NC 27710, USA
| | - Mark Foster
- Center for In Vivo Microscopy, Duke University Medical Center, Department of Radiology, Durham, NC 27710, USA
| | - Gary P Cofer
- Center for In Vivo Microscopy, Duke University Medical Center, Department of Radiology, Durham, NC 27710, USA
| | - Neil Medvitz
- Department of Pathology, and Preston Robert Tisch Brain Tumor Center, Duke University Medical Center, Durham, NC 27710, USA
| | - Anne F Buckley
- Department of Pathology, and Preston Robert Tisch Brain Tumor Center, Duke University Medical Center, Durham, NC 27710, USA
| | - Andreas K Badea
- Center for In Vivo Microscopy, Duke University Medical Center, Department of Radiology, Durham, NC 27710, USA
| | - William C Wetsel
- Departments of Psychiatry and Behavioral Sciences, Cell Biology, and Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Carol A Colton
- Department of Neurology, Duke University Medical Center, Durham, NC 27710, USA
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14
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Fischer FU, Wolf D, Scheurich A, Fellgiebel A. Altered whole-brain white matter networks in preclinical Alzheimer's disease. NEUROIMAGE-CLINICAL 2015; 8:660-6. [PMID: 26288751 PMCID: PMC4536470 DOI: 10.1016/j.nicl.2015.06.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 06/17/2015] [Accepted: 06/20/2015] [Indexed: 11/28/2022]
Abstract
Surrogates of whole-brain white matter (WM) networks reconstructed using diffusion tensor imaging (DTI) are novel markers of structural brain connectivity. Global connectivity of networks has been found impaired in clinical Alzheimer's disease (AD) compared to cognitively healthy aging. We hypothesized that network alterations are detectable already in preclinical AD and investigated major global WM network properties. Other structural markers of neurodegeneration typically affected in prodromal AD but seeming largely unimpaired in preclinical AD were also examined. 12 cognitively healthy elderly with preclinical AD as classified by florbetapir-PET (mean age 73.4 ± 4.9) and 31 age-matched controls without cerebral amyloidosis (mean age 73.1 ± 6.7) from the ADNI were included. WM networks were reconstructed from DTI using tractography and graph theory. Indices of network capacity and the established imaging markers of neurodegeneration hippocampal volume, and cerebral glucose utilization as measured by fludeoxyglucose-PET were compared between the two groups. Additionally, we measured surrogates of global WM integrity (fractional anisotropy, mean diffusivity, volume). We found an increase of shortest path length and a decrease of global efficiency in preclinical AD. These results remained largely unchanged when controlling for WM integrity. In contrast, neither markers of neurodegeneration nor WM integrity were altered in preclinical AD subjects. Our results suggest an impairment of WM networks in preclinical AD that is detectable while other structural imaging markers do not yet indicate incipient neurodegeneration. Moreover, these findings are specific to WM networks and cannot be explained by other surrogates of global WM integrity.
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Affiliation(s)
- Florian Udo Fischer
- University Medical Center Mainz, Untere Zahlbacher Str. 8, Mainz 55131, Germany
| | - Dominik Wolf
- University Medical Center Mainz, Untere Zahlbacher Str. 8, Mainz 55131, Germany
| | - Armin Scheurich
- University Medical Center Mainz, Untere Zahlbacher Str. 8, Mainz 55131, Germany
| | - Andreas Fellgiebel
- University Medical Center Mainz, Untere Zahlbacher Str. 8, Mainz 55131, Germany
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15
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Bilkei-Gorzo A. Genetic mouse models of brain ageing and Alzheimer's disease. Pharmacol Ther 2014; 142:244-57. [DOI: 10.1016/j.pharmthera.2013.12.009] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 11/26/2013] [Indexed: 12/21/2022]
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16
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Racine AM, Adluru N, Alexander AL, Christian BT, Okonkwo OC, Oh J, Cleary CA, Birdsill A, Hillmer AT, Murali D, Barnhart TE, Gallagher CL, Carlsson CM, Rowley HA, Dowling NM, Asthana S, Sager MA, Bendlin BB, Johnson SC. Associations between white matter microstructure and amyloid burden in preclinical Alzheimer's disease: A multimodal imaging investigation. NEUROIMAGE-CLINICAL 2014; 4:604-14. [PMID: 24936411 PMCID: PMC4053642 DOI: 10.1016/j.nicl.2014.02.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 01/29/2014] [Accepted: 02/10/2014] [Indexed: 10/30/2022]
Abstract
Some cognitively healthy individuals develop brain amyloid accumulation, suggestive of incipient Alzheimer's disease (AD), but the effect of amyloid on other potentially informative imaging modalities, such as Diffusion Tensor Imaging (DTI), in characterizing brain changes in preclinical AD requires further exploration. In this study, a sample (N = 139, mean age 60.6, range 46 to 71) from the Wisconsin Registry for Alzheimer's Prevention (WRAP), a cohort enriched for AD risk factors, was recruited for a multimodal imaging investigation that included DTI and [C-11]Pittsburgh Compound B (PiB) positron emission tomography (PET). Participants were grouped as amyloid positive (Aβ+), amyloid indeterminate (Aβi), or amyloid negative (Aβ-) based on the amount and pattern of amyloid deposition. Regional voxel-wise analyses of four DTI metrics, fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da), and radial diffusivity (Dr), were performed based on amyloid grouping. Three regions of interest (ROIs), the cingulum adjacent to the corpus callosum, hippocampal cingulum, and lateral fornix, were selected based on their involvement in the early stages of AD. Voxel-wise analysis revealed higher FA among Aβ+ compared to Aβ- in all three ROIs and in Aβi compared to Aβ- in the cingulum adjacent to the corpus callosum. Follow-up exploratory whole-brain analyses were consistent with the ROI findings, revealing multiple regions where higher FA was associated with greater amyloid. Lower fronto-lateral gray matter MD was associated with higher amyloid burden. Further investigation showed a negative correlation between MD and PiB signal, suggesting that Aβ accumulation impairs diffusion. Interestingly, these findings in a largely presymptomatic sample are in contradistinction to relationships reported in the literature in symptomatic disease stages of Mild Cognitive Impairment and AD, which usually show higher MD and lower FA. Together with analyses showing that cognitive function in these participants is not associated with any of the four DTI metrics, the present results suggest an early relationship between PiB and DTI, which may be a meaningful indicator of the initiating or compensatory mechanisms of AD prior to cognitive decline.
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Key Words
- AD risk
- ANCOVA, Analysis of Covariance
- ANTs, Advanced Normalization Tools
- APOE4, apolipoprotein E gene ε4
- Alzheimer's disease
- Amyloid imaging
- Aβ+, amyloid positive
- Aβi, amyloid indeterminate
- Aβ−, amyloid negative
- BET, Brain Extraction Tool
- Cingulum–CC, cingulum adjacent to corpus callosum
- Cingulum–HC, hippocampal cingulum (projecting to medial temporal lobe)
- DTI, Diffusion Tensor Imaging
- DTI-TK, Diffusion Tensor Imaging Toolkit
- DVR, distribution volume ratio
- Da, axial diffusivity
- Dr, radial diffusivity
- FA, fractional anisotropy
- FH, (parental) family history
- FSL, FMRIB Software Library
- FUGUE, FMRIB's utility for geometrically unwarping EPIs
- FWE, family wise error
- GM, gray matter
- HARDI, high angular resolution diffusion imaging
- ICBM, International Consortium for Brain Mapping
- MD, mean diffusivity
- PCC, posterior cingulate cortex
- PIB, Pittsburgh compound B
- PRELUDE, phase region expanding labeler for unwrapping discrete estimates
- RAVLT, Rey Auditory Verbal Learning Test
- SPM, Statistical Parametric Mapping
- TMT, Trail Making Test
- WASI, Wechsler Abbreviated Scale of Intelligence
- WM, white matter
- WRAP, Wisconsin Registry for Alzheimer's Prevention
- WRAT, Wide Range Achievement Test
- White matter
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Affiliation(s)
- Annie M Racine
- Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Nagesh Adluru
- Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Andrew L Alexander
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, WI 53705, USA ; Department of Psychiatry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53719, USA
| | - Bradley T Christian
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Ozioma C Okonkwo
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Jennifer Oh
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Caitlin A Cleary
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Alex Birdsill
- Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Ansel T Hillmer
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Department of Psychiatry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53719, USA
| | - Dhanabalan Murali
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Todd E Barnhart
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Catherine L Gallagher
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Cynthia M Carlsson
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Howard A Rowley
- Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - N Maritza Dowling
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Sanjay Asthana
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Mark A Sager
- Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Barbara B Bendlin
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Sterling C Johnson
- Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI 53705, USA ; Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA ; Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, WI 53705, USA
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