Alterations of white matter diffusion anisotropy in early deafness

Abstract

To explore the effects of white matter in the absence of auditory input in the early deaf, we conducted a tract-based statistical analysis of the diffusion tensor anisotropy and the voxel-based morphometry in the white matter of 13 early deaf and 29 hearing individuals. Deaf individuals showed significant decreases in diffusion anisotropy and in regional volume reductions within the temporal white matter. Decreased anisotropy was also found at the internal capsule, superior longitudinal fasciculus, and the inferior frontal white matter. In contrast, the forceps major of the corpus callosum, where interhemispheric connections between visual cortices exist, showed increased anisotropy. We interpreted these white matter alterations in terms of both disuse-driven atrophy and compensatory plasticity in the early deaf.

Altered White Matter Integrity in Adolescents with Prelingual Deafness: A High-Resolution Tract-Based Spatial Statistics Imaging Study

“…This finding shows that WM anisotropy changes are largely independent of functional use. These findings are partially in agreement with those of previous studies with adults, 10,11,18 indicating that prelingual deafness in adolescents is mainly consistent with that in adults but shows certain differences. Compared with other imaging techniques, DTI is more sensitive because it can detect WM microstructural changes well before a macrostructural loss of WM becomes measurable by other procedures, such as voxel-based morphometry.…”

“…Axons in the most caudal region of the corpus callosum-the splenium-connect the occipital, temporal, and parietal regions. 35 The FA decreases we found in the posterior part of the corpus callosum are nearly the same as the parcellated areas corresponding to the temporal lobe projections in the study by Huang et al 36 However, our finding conflicts with the results of the study by Kim et al, 11 who observed increased (rather than decreased) FA in the corpus callosum. This discrepancy may be attributed to the younger age of our participants, who may have not had enough visual exposure.…”

“…10,11 The primary auditory cortex is believed to be involved in most of the high-level processing that takes place in sound processing and is essential for recognizing when sound starts, stops, or changes pitch. 20,21 The FA loss is more significant in the right STG and HG than in the left hemisphere, and the significant decreased FA areas in or near the right STG and HG are much greater than on the left side.…”

“…9 However, despite treatment, gross alterations in brain anatomy may still prevail as a consequence of prelingual deafness, but the localization and extent of such changes are not well understood. Previous studies 10,11 identified areas showing relatively small structural changes, which were mainly located in the STG, HG, and corpus callosum. Our hypothesis was that the prelingual deafness-induced WM alterations (locations of significant changes in diffusion tensor imaging metrics) in adolescents were mainly consistent with the changes reported in adults.…”

“…Our hypothesis was that the prelingual deafness-induced WM alterations (locations of significant changes in diffusion tensor imaging metrics) in adolescents were mainly consistent with the changes reported in adults. 11 Considering the developing brain is both more vulnerable to deprivation and more plastic than the adult brain, we further hypothesized that any brain morphologic alterations should be larger in prelingually deaf adolescents when compared with adults.…”