Figure 6. Axial, coronal, and sagittal views through a region of the brain centred on the superior longitudinal fasciculus. Top: best estimates of fibre orientations obtained from the diffusion tensor, overlaid on a fractional anisotropy map. Bottom: regions of crossing fibres highlighted in white, as defined using a mixture model of two tensors, with two resulting estimates of fibre orientation. Light grey regions indicate the presence of anisotropic single tensor tissue (single fibre bundle); dark grey indicates isotropic diffusion (mostly grey matter). Green ovals indicate regions where crossing fibres may be wrongly interpreted as representing coherent single fibre structure in single tensor analysis.