Symmetries in human brain language pathways correlate with verbal recall

Lateralization of language to the left hemisphere is considered a key aspect of human brain organization. We used diffusion tensor MRI to perform in vivo virtual dissection of language pathways to assess the relationship between brain asymmetry and cognitive performance in the normal population. Our findings suggest interhemispheric differences in direct connections between Broca's and Wernicke's territories, with extreme leftward lateralization in more than half of the subjects and bilateral symmetrical distribution in only 17.5% of the subjects. Importantly, individuals with more symmetric patterns of connections are better overall at remembering words using semantic association. Moreover, preliminary…