Longitudinal group brain deformation differences and brain– behavioral correlations in the corpus callosum. The brain image (a sagittal slice) shows areas of significant difference in relative voxel size over 15 months in instrumental (n = 15) versus control (n = 16) children in terms of a t-statistical color map of the significant clusters superimposed on an average MR image of all children (n = 31). The yellow arrow points to the corpus callosum. To illustrate the group differences, the relative voxel size is plotted for each group at the most significant (peak) voxel in the corpus callosum (x = 14, y = −24, z = 30; t = 5.2, p < 0.05 at whole-brain cluster threshold) (a). The significant positive correlation of relative voxel size with behavioral difference scores (from time 1 to time 2) of each child is shown for the left-hand motor test at the peak voxel in the corpus callosum (b).

Longitudinal group brain deformation differences and brain– behavioral correlations in primary motor area. The brain image (a horizontal slice) shows areas of significant difference in relative voxel size over 15 months in instrumental (n = 15) versus control (n = 16) children in terms of a t-statistical color map of the significant clusters superimposed on an average MR image of all children (n = 31). The yellow arrow points to the primary motor area (right precentral gyrus). To illustrate the group differences, the relative voxel size (expressed as the mean by the horizontal dark black line, 25% and 75% quartiles by the top and bottom lines of the box, SDs by the errors bars, and outliers by circles) is plotted for each group at the most significant (peak) voxel in the right precentral gyrus (x = 40, y = −7, z = 57; t = 4.2, p < 0.05 at whole-brain cluster threshold) (a). A voxel with a relative voxel size of 1 indicates no brain deformation change from time 1, values >1 indicate voxel expansion, and values <1 indicate voxel contraction. For example, a value of 1.1 at voxel X indicates a 10% expansion from time 1, whereas 0.9 indicates a 10% contraction (this also applies to Figs. 2, 3). The significant positive correlation of relative voxel size with behavioral difference scores (from time 1 to time 2) of each child on the left-hand motor test that was found at the peak voxel in the right precentral gyrus is shown in b.

Longitudinal group brain deformation differences and brain– behavioral correlations in right primary auditory area. The brain image (a horizontal slice) shows areas of significant difference in relative voxel size over 15 months in instrumental (n = 15) versus control (n = 16) children in terms of a t-statistical color map of the significant clusters superimposed on an average MR image of all children (n = 31). The yellow arrow points to the right primary auditory region (lateral aspect of Heschl’s gyrus). To illustrate the group differences, the relative voxel size is plotted for each group at the most significant (peak) voxel in the right primary auditory region (x = 55, y = −8, z = 10; t = 4.9, p < 0.1 at a priori cluster threshold) (a). The significant positive correlations of relative voxel size with behavioral difference scores (from time 1 to time 2) of each child is shown for the melody/rhythm test at the peak voxel in the right primary auditory area (b).