Neurophysiological studies in dyslexia.

Using sophisticated computer graphics technologies and sensitive methods, our original dyslexia study of dyslexic boys delineated specific areas of the brain which in combination could constitute a "physiological signature" of dyslexia. In addition to identifying aberrant brain function in the traditional language-associated left posterior region, we also observed medial frontal lobe differences from normals, a finding confirmed by others in recent research. Our subsequent study sought to refine further current definitional subgroupings within the broad entity known as dyslexia-pure. Indeed language-based subgroups appear to have identifiable and differing topographic signatures. Furthermore, based on correlations between neuropsychological test scores and neurophysiological measurements, we suggest that subgroup electrophysiological differences may reflect compensatory as well as pathological brain activity. We believe that the currently expanding understanding of the neurophysiology of dyslexia will lead eventually to improved diagnosis and remediation of this learning disability. The detailed mapping of brain electrical activity shows promise of providing the neuropsychologist and learning disability specialist with another "perspective" on reading disability. This technique may prove valuable in the diagnosis of dyslexia at an early age and in the tailoring of the learning experience to a child's specific deficits and capabilities.