Structural imaging in dyslexia: The planum temporale

The search for a neurobiological substrate for dyslexia has focused on anom alous planum symmetry. The results of imaging studies of the planum have be en inconsistent, perhaps due to diagnostic uncertainty, technical differenc es in measurement criteria, and inadequate control of handedness, sex, and cognitive ability. Although structural imaging studies have nor clarified t he neurobiology of reading disability, converging evidence suggests that va riation in asymmetry of the planum temporale does have functional significa nce. Studies in a variety of populations have shown a significant associati on between planar asymmetry, the strength of hand preference, and general v erbal skills such as vocabulary and comprehension. Future structural imagin g studies of dyslexia should match participants on hand preference and gene ral verbal ability in order to determine the relationship between brain str ucture and written and oral language, (C) 2000 Wiley-Liss. Inc.