Fig. 3.

Regions of significant FSIQ-by-age interaction in analyses of tissue contraction or expansion using volume-preserved warping (VPW_i = β₀ + β₁ × age + β₂ × age² + β₃ × age³ + β₄ × sex + β₅ × age × sex + β₆ × FSIQ + β₇ × FSIQ × sex + β₈ × FSIQ × age, where VPW_i is the set of tissue volume measurements). VPW warps a binarized image of the brain to generate a normalized image with varying pixel intensities. In this normalized image, regions of high intensity denote the regions compressed by the deformation field, and regions of low intensity denote the regions that were expanded by the deformation field. The color bar indicates the statistical significance of the interaction. A large territory of right frontal white matter shows significant FSIQ-by-age interaction. This interaction is shown in the three-dimensional graph, where greater VPW intensity is denoted in red color and reflects greater tissue volume, and blue-green colors indicate reduced VPW intensity and smaller tissue volumes. In the right frontal lobe, adults show inverse correlations of FSIQ with white matter volume, whereas in children no correlation is detected. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)