title: Thalamocortical Connectivity and Microstructural Changes in Congenital and Late Blindness.
abstract: There is ample evidence that the occipital cortex of congenitally blind individuals processes nonvisual information. It remains a debate whether the cross-modal activation of the occipital cortex is mediated through the modulation of preexisting corticocortical projections or the reorganisation of thalamocortical connectivity. Current knowledge on this topic largely stems from anatomical studies in animal models. The aim of this study was to test whether purported changes in thalamocortical connectivity in blindness can be revealed by tractography based on diffusion-weighted magnetic resonance imaging. To assess the thalamocortical network, we used a clustering method based on the thalamic white matter projections towards predefined cortical regions. Five thalamic clusters were obtained in each group representing their cortical projections. Although we did not find differences in the thalamocortical network between congenitally blind individuals, late blind individuals, and normal sighted controls, diffusion tensor imaging (DTI) indices revealed significant microstructural changes within thalamic clusters of both blind groups. Furthermore, we find a significant decrease in fractional anisotropy (FA) in occipital and temporal thalamocortical projections in both blind groups that were not captured at the network level. This suggests that plastic microstructural changes have taken place, but not in a degree to be reflected in the tractography-based thalamocortical network.
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.
authors.forename: N H
authors.identifier: 0000-0002-8119-8973
authors.initials: NH
authors.lastname: Reislev
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: T B
authors.initials: TB
authors.lastname: Dyrby
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Department of Neurology, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark.
authors.forename: H R
authors.initials: HR
authors.lastname: Siebner
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Lundell
authors.affiliation: Laboratory of Neuropsychiatry, Psychiatric Centre Copenhagen, Copenhagen, Denmark; School of Optometry, Université de Montréal, Montréal, QC, Canada.
authors.forename: M
authors.identifier: 0000-0002-5173-5862
authors.initials: M
authors.lastname: Ptito
authors.affiliation: School of Optometry, Université de Montréal, Montréal, QC, Canada; BRAINlab, Danish Centre for Sleep Medicine, Rigshospitalet, Department of Clinical Neurophysiology, University of Copenhagen, Copenhagen, Denmark; Department of Radiology & Biomedical Imaging, Yale University, 300 Cedar Street, New Haven, CT 06520, USA.
authors.forename: R
authors.initials: R
authors.lastname: Kupers
mesh_terms: D000328:Adult; D016880:Anisotropy; D001766:Blindness / Q000151:congenital* / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging; D006801:Humans; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology; D013788:Thalamus / Q000473:pathology*; D066127:White Matter / Q000473:pathology*