Differences in brain structure in deaf persons on MR imaging studied with voxel-based morphometry

Area of Science:

• Neuroscience
• Neuroimaging
• Auditory Neuroscience

Background:

• Early sensory deprivation can alter brain structure and function.
• Gross anatomical effects of early-onset deafness are not fully understood.
• Voxel-based morphometry (VBM) is a key tool for analyzing brain structure differences.

Purpose of the Study:

• To compare brain anatomy in prelingually deaf individuals versus hearing controls using VBM.
• To investigate potential hypoplasia in temporal lobe regions associated with hearing and speech in deaf subjects.
• To test the hypothesis that early deafness leads to structural brain alterations.

Main Methods:

• Volumetric T1-weighted MRI scans from 53 deaf and 51 hearing participants were analyzed.
• VBM was employed for spatial normalization and segmentation of brain images.
• Statistical parametric mapping identified voxel-wise differences and asymmetries between groups.

Main Results:

• A significant white matter deficit was observed in the left posterior superior temporal gyrus (STG) of deaf individuals.
• This deficit was located inferior to the auditory cortex, suggesting impacts on auditory/speech tracts.
• While overall gray matter asymmetries were similar, a loss of asymmetry was noted in the posterior STG white matter in deaf subjects.

Conclusions:

• Early deafness results in observable gross anatomical changes in the brain.
• The identified white matter deficit in the left posterior STG supports the hypothesis of hypoplasia in auditory/speech pathways.
• Despite localized changes, major hemispheric asymmetries appear largely preserved in early deafness.