Reorganization of neural circuits in the blind on diffusion direction analysis.

The neural reorganization of the visual cortex of early blind individuals was evaluated using voxel-by-voxel analysis of diffusion tensor images with regard to the diffusion direction, diffusion anisotropy and diffusivity. Reduced anisotropy and increased diffusivity was found mainly in the visual pathways of 18 early blind individuals as opposed to 25 sighted individuals. Alteration of the diffusion direction was detected not only in the visual pathways but also in nonvisual pathways such as the u fibers of the parietal lobe, the sagittal striatum, the pulvinar and the inferior and superior longitudinal fasciculi. The alteration of regional diffusion direction, reduced anisotropy and increased diffusivity in early blind individuals imply the neural reorganization for functional adaptation to the loss of visual input during the early development period.