TEMPORAL-LOBE SURFACE-AREA MEASUREMENTS ON MRI IN NORMAL AND DYSLEXICREADERS

In a neuroanatomical study of dyslexia, measurements were made of the superior surface of the temporal lobe (SSTL) on MRI scans in a sample of 17 dyslexics and 21 non-dyslexic subjects. Both anterior and poster ior halves of the SSTL area showed significant leftward asymmetry in n on-dyslexics, but showed symmetry in dyslexics. The total SSTL area sh owed greater leftward asymmetry in non-dyslexics than in dyslexics. Th e dyslexics also revealed a significant correlation (r=0.69, P=0.005) between Woodcock-Johnson Passage Comprehension scores and posterior SS TL asymmetry, such that those with higher scores had more leftward asy mmetry. This suggests that among dyslexics the direction of SSTL asymm etry may serve as a risk factor and/or a marker for the severity of re ading comprehension problems.