title: A multiscale approach for the reconstruction of the fiber architecture of the human brain based on 3D-PLI.
abstract: Structural connectivity of the brain can be conceptionalized as a multiscale organization. The present study is built on 3D-Polarized Light Imaging (3D-PLI), a neuroimaging technique targeting the reconstruction of nerve fiber orientations and therefore contributing to the analysis of brain connectivity. Spatial orientations of the fibers are derived from birefringence measurements of unstained histological sections that are interpreted by means of a voxel-based analysis. This implies that a single fiber orientation vector is obtained for each voxel, which reflects the net effect of all comprised fibers. We have utilized two polarimetric setups providing an object space resolution of 1.3 μm/px (microscopic setup) and 64 μm/px (macroscopic setup) to carry out 3D-PLI and retrieve fiber orientations of the same tissue samples, but at complementary voxel sizes (i.e., scales). The present study identifies the main sources which cause a discrepancy of the measured fiber orientations observed when measuring the same sample with the two polarimetric systems. As such sources the differing optical resolutions and diverging retardances of the implemented waveplates were identified. A methodology was implemented that enables the compensation of measured different systems' responses to the same birefringent sample. This opens up new ways to conduct multiscale analysis in brains by means of 3D-PLI and to provide a reliable basis for the transition between different scales of the nerve fiber architecture.
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Structural and Functional Organization of the Human Brain, Research Centre Jülich Jülich, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Reckfort
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Structural and Functional Organization of the Human Brain, Research Centre Jülich Jülich, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Wiese
authors.affiliation: Institute of Neuroscience and Medicine (INM-4), Medical Imaging Physics, Research Centre Jülich Jülich, Germany ; Department of Mathematics and Natural Sciences, University of Wuppertal Wuppertal, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Pietrzyk
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Structural and Functional Organization of the Human Brain, Research Centre Jülich Jülich, Germany ; Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital, RWTH Aachen University and JARA Translational Brain Medicine Aachen, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Zilles
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Structural and Functional Organization of the Human Brain, Research Centre Jülich Jülich, Germany ; Cécile and Oskar Vogt Institute for Brain Research, Heinrich-Heine University Düsseldorf Düsseldorf, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Amunts
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Structural and Functional Organization of the Human Brain, Research Centre Jülich Jülich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Axer
keywords: brain; connectome; fiber orientation; multiscale approach; polarized light imaging