Procedure for microstructural quantification of the callosal segments. Colors of the callosal projections correspond to the colors of the cortical areas. (A) ROI definition via atlas-based automatic parcellation. Eleven homotopic pairs of ROIs were chosen as target regions for probabilistic diffusion tractography. This results in the identification of callosal segments for each homotopic ROI pair. (B) Averaged callosal segments are visualized on a common template space. (C) For each individual participant, we created image maps for FA, INVF, and MWF. The individual callosal segments were transformed into each one of these maps to gain an estimate of FA, INVF, and MWF values.