Fig. 1.

Left–right hemispheric differences in perisylvian language pathways. (A) Tractography reconstruction of language pathways in the average DT-MRI data set. In both hemispheres, the anterior indirect segment (green) connects posterior inferior frontal cortex (B, Broca's territory) and inferior parietal cortex (G, Geschwind's territory), whereas the posterior indirect segment (yellow) connects superior posterior temporal cortex (W, Wernicke's territory) and Geschwind's territory. In the left hemisphere, but not in the right, the direct segment (red) connects Wernicke's and Broca's territories. (B–D) Segment overlap maps derived from dissection of single brains show L-R asymmetry only in the direct segment (B) and L-R symmetry in the anterior indirect (C) and posterior indirect (D) segments. “Hotter” (yellow) colors correspond to a higher degree of overlap, whereas “cooler” (red) colors reflect less overlap.