Poster C42, Sunday, March 25, 1:00-3:00 pm, Exhibit Hall C
The impact of literacy on microstructural properties of white matter
Falk Huettig1, Vidur Mahajan2, Madhuri Barnwal2, Nishant Lohagun3, Ouroz Khan3, Anuradha Singh3, Deepshikha Misra 3, Vaishna Narang3, Ramesh Mishra4, Alexis Hervais-Adelman1; 1Max Planck Institute for Psycholinguistics Nijmegen, 2Mahajan Imaging Delhi, 3Jawaharlal Nehru University New Delhi, 4University of Hyderabad
Learning to read is a profound cultural experience, requiring systematic instruction, and intensive practice. Previous research suggests that literacy acquisition results in substantial structural reorganization of the brain even in adults, but conclusions drawn from these studies are limited because of important methodological constraints and/or the small number of illiterate participants involved. In a large-scale study we recruited 48 completely illiterate and 13 literate individuals from informal settlements in New Delhi (India). Both groups were matched for their socioeconomic background. Participants underwent diffusion-weighted imaging which is more sensitive than other morphological analyses such as VBM. Four DTI sequences (2mm isotropic voxels, b=1000s/mm2, 64 directions, two sequences with AP phase-encoding, two with PA phase-encoding) were acquired. Raw diffusion images were processed using top up in FSL to correct for susceptibility artefacts and eddy to correct for eddy current-induced distortions and participant movements. FSL's dtifit was used to estimate diffusion properties. Fractional anisotropy and mean diffusivity images were then 'skeletonised' using the procedure implemented for Tract-Based Spatial Statistics, to enable voxel-wise analyses. Group-wise differences were tested using Randomise to implement a non-parametric unpaired t-test. Resulting statistical images were corrected for multiple comparisons using threshold-free cluster enhancement. Significant differences in mean diffusivity were found in a large number of white matter tracts bilaterally, including the inferior fronto-occipital fasciculus, the inferior and superior longitudinal fasciculi the anterior thalamic radiations and the forceps major. This pattern suggests that literacy has a broad impact on the white matter underlying and connecting sensory and language-related brain regions.
Topic Area: LANGUAGE: Development & aging