title: The role of myelination in measures of white matter integrity: Combination of diffusion tensor imaging and two-photon microscopy of CLARITY intact brains.
abstract: Diffusion tensor imaging (DTI) is used extensively in neuroscience to noninvasively estimate white matter (WM) microarchitecture. However, the diffusion signal is inherently ambiguous because it infers WM structure from the orientation of water diffusion and cannot identify the biological sources of diffusion changes. To compare inferred WM estimates to directly labeled axonal elements, we performed a novel within-subjects combination of high-resolution ex vivo DTI with two-photon laser microscopy of intact mouse brains rendered optically transparent by Clear Lipid-exchanged, Anatomically Rigid, Imaging/immunostaining compatible, Tissue hYdrogel (CLARITY). We found that myelin basic protein (MBP) immunofluorescence significantly correlated with fractional anisotropy (FA), especially in WM regions with coherent fiber orientations and low fiber dispersion. Our results provide evidence that FA is particularly sensitive to myelination in WM regions with these characteristics. Furthermore, we found that radial diffusivity (RD) was only sensitive to myelination in a subset of WM tracts, suggesting that the association of RD with myelin should be used cautiously. This combined DTI-CLARITY approach illustrates, for the first time, a framework for using brain-wide immunolabeling of WM targets to elucidate the relationship between the diffusion signal and its biological underpinnings. This study also demonstrates the feasibility of a within-subject combination of noninvasive neuroimaging and tissue clearing techniques that has broader implications for neuroscience research.
authors.affiliation: Center for Psychiatric Neuroscience, The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Division of Psychiatry Research, Zucker Hillside Hospital, Northwell Health, 75-59 263rd Street, Glen Oaks, NY 11004, USA. Electronic address: echang1@northwell.edu.
authors.forename: Eric H
authors.initials: EH
authors.lastname: Chang
authors.affiliation: Center for Psychiatric Neuroscience, The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Division of Psychiatry Research, Zucker Hillside Hospital, Northwell Health, 75-59 263rd Street, Glen Oaks, NY 11004, USA.
authors.forename: Miklos
authors.initials: M
authors.lastname: Argyelan
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Manisha
authors.initials: M
authors.lastname: Aggarwal
authors.affiliation: Center for Psychiatric Neuroscience, The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Division of Psychiatry Research, Zucker Hillside Hospital, Northwell Health, 75-59 263rd Street, Glen Oaks, NY 11004, USA.
authors.forename: Toni-Shay S
authors.initials: TS
authors.lastname: Chandon
authors.affiliation: Center for Psychiatric Neuroscience, The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Division of Psychiatry Research, Zucker Hillside Hospital, Northwell Health, 75-59 263rd Street, Glen Oaks, NY 11004, USA; Hofstra Northwell School of Medicine, Departments of Psychiatry and Molecular Medicine, Hofstra University, Hempstead, NY, USA; Department of Psychology, University of California at Los Angeles, 1285 Franz Hall Box 951563, Los Angeles, CA 90095, USA.
authors.forename: Katherine H
authors.initials: KH
authors.lastname: Karlsgodt
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205, USA.
authors.forename: Susumu
authors.initials: S
authors.lastname: Mori
authors.affiliation: Center for Psychiatric Neuroscience, The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Division of Psychiatry Research, Zucker Hillside Hospital, Northwell Health, 75-59 263rd Street, Glen Oaks, NY 11004, USA; Hofstra Northwell School of Medicine, Departments of Psychiatry and Molecular Medicine, Hofstra University, Hempstead, NY, USA.
authors.forename: Anil K
authors.initials: AK
authors.lastname: Malhotra
mesh_terms: D000818:Animals; D016880:Anisotropy; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005455:Fluorescent Antibody Technique; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D009186:Myelin Sheath; D066127:White Matter / Q000000981:diagnostic imaging*
keywords: Fractional anisotropy; Multimodal imaging; Myelin basic protein; Neuroimaging; Tissue clearing; Whole brain immunolabeling