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Neural Plasticity
Volume 2017, Article ID 9807512, 11 pages
https://doi.org/10.1155/2017/9807512
Research Article

Thalamocortical Connectivity and Microstructural Changes in Congenital and Late Blindness

1Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
2Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens Lyngby, Denmark
3Department of Neurology, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark
4Laboratory of Neuropsychiatry, Psychiatric Centre Copenhagen, Copenhagen, Denmark
5School of Optometry, Université de Montréal, Montréal, QC, Canada
6BRAINlab, Danish Centre for Sleep Medicine, Rigshospitalet, Department of Clinical Neurophysiology, University of Copenhagen, Copenhagen, Denmark
7Department of Radiology & Biomedical Imaging, Yale University, 300 Cedar Street, New Haven, CT 06520, USA

Correspondence should be addressed to N. H. Reislev; kd.rmcrd@ranin

Received 24 November 2016; Revised 2 February 2017; Accepted 19 February 2017; Published 13 March 2017

Academic Editor: Jiawei Zhou

Copyright © 2017 N. H. Reislev et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.