Fig. 6

Expansion in Matrix-Like Volume Results from a Selective Increase in High-Bias Voxels. Increased matrix-like volume could result from multiple tissue-level changes to matrix or striosome. Histogram analyses can identify the type of voxels (high- vs. low-bias; matrix vs. striosome) that were changed in autism spectrum disorder (ASD) relative to Typically Developing (TD) controls, and thus allowed us to evaluate the potential tissue-level changes hypothesized in Fig. 5. We performed histogram analyses on the matrix-like and striosome-like probability distributions (1.0 to 0.55 for each), quantifying the voxels with compartment-specific connectivity in 0.01 unit bins (each circle = one bin, 45 total bins). Matrix- and striosome-like histograms followed similar patterns, but matrix-like volume diverged in ASD at the highest probability bins (left-to-right = high-to-low probability); below probabilities of approximately 0.95, matrix-like volume was indistinguishable in ASD and TD. Striosome-like volume did not differ between ASD and TD at any part of the probability distribution (data not shown); expansion in matrix-like volume cannot be attributed to a spurious overcount of matrix-like voxels due to a decrease in striosome-favoring connectivity. **, p = 2.5 × 10^–4; *, p ≤ 0.02