Fig. 4: Associations of hair mercury level with fractional anisotropy (FA)(Nā=ā919).

Greater hair mercury level was significantly associated with greater FA in widespread bilateral white matter areas. Colored bars indicate TFCE scores. TFCE score is unit-free and reflects both voxelās height and the sum of the spatially contiguous voxels supporting it; therefore, it reflects both the strength and extent of effects. All results are overlaid on the mean preprocessed (including normalization) but unsmoothed FA images of participants from whom the DARTEL template was created (meaning that this mean image is in the normalized space). a Regions with significant results. The results shown were obtained using a threshold Pā<ā0.05, corrected for multiple comparisons based on 5000 permutations using the TFCE score. b, c Partial residual plots with the trend line depicting the associations between residuals of the logarithms of hair mercury levels and (b) residuals of mean FA in the significant cluster of the left posterior areas and (c) residuals of mean FA in the significant cluster of right middle white matter areas with other confounding factors controlled.