Figure 7.

Cross-trait genetic correlations between FA and FIQ, PIQ and OBJ scores, with maps of correlation coefficients r_a, corrected for age and sex (left), and the FDR-adjusted values for the significance of r_a (right). The MNI coordinate (mm) of the slices is indicated at the beginning of each row. For each of these IQ scores, cross-trait analysis was limited to the brain regions where phenotypic correlation between FA and that IQ score was significant. Common genetic factors affect both FA and FIQ, PIQ or OBJ in the cingulum and isthmus of the corpus callosum, a commissural pathway innervating the parietal cortex, which is crucial for multi-modal sensory integration (x = 3), the cerebral peduncles (for OBJ) and ILF/IFO (right > left, for OBJ) (z = −14), the posterior limbs of the internal capsule and the left posterior thalamic radiation/optic radiation (for PIQ and OBJ) (z = 3), bilateral anterior corona radiata and right superior fronto-occipital fasciculus (z = 20), and bilateral superior and posterior corona radiata (for PIQ and OBJ) (z = 35). There were no negative genetic correlations between IQ scores and white matter integrity, i.e., negative values of r_a were not significant.