Fig. 5

Potential Tissue Alterations Underlying Increased Matrix-like Volume. Each diffusion voxel (resolution = 2 mm isotropic) has the potential to include both matrix and striosome. The character of the tissue included in each voxel determines whether it will be parcellated as matrix-like, striosome-like, or indeterminate. Three potential changes to striatal tissue – a decrease in striosome numbers or projections to the striosome (A); a simplification of striosomal branching and complexity (architecture, B); an increase in matrix volume with no change in striosome (C) – can explain the increase in matrix-like volume we detected in ASD. Granular measurements of compartment bias throughout the probability distribution (histogram analysis, Fig. 6) allow us to infer the nature of the tissue abnormality in ASD that leads to an expansion in matrix-like volume