In our SZ group, we observed statistically significant relation between FA values and PANSS scores in the temporal and posterior parietal segments of CC white matter fibers connecting the two hemispheres. The FA of callosal fibers in the temporal segment was significantly negatively associated with the score of the PANSS negative. Several studies have reported that executive function in schizophrenia was associated with the PANSS negative score (Clark, Warman, & Lysaker, 2010; Kishi et al., 2010; Rodriguez‐Jimenez et al., 2010). Microstructural abnormalities of callosal fiber in the temporal segment may be associated with negative symptom in schizophrenia. On the other hand, the FA of callosal fibers in the posterior parietal segment was significantly positively associated with all scores of the PANSS, indicating higher FA related to the higher severity of the symptoms. These results suggest paradoxical effect of anisotropy of callosal fibers in the posterior parietal segment on psychiatric symptom. However, these results should be interpreted cautiously because there was no significant difference in FA of callosal fibers in the posterior parietal segment between the SZ and HC groups. There
