Evoked potential measures of interhemispheric transfer time in reading disabled and normal boys

Abstract

Previous research has implicated dysfunctions in interhemispheric interaction in the etiology of dyslexia. The present study was designed to examine whether dyslexics differ from matched controls on visual evoked potential measures of interhemispheric transfer time (IHTT). Checkerboard flashes were presented hemiretinally while evoked responses were recorded from right and left side occipital scalp locations. IHTT was computed separately in response to right and left visual field presentations. Dyslexics were found to have faster IHTT from right‐to‐left hemisphere and slower IHTT from left‐to‐right hemisphere compared with controls. Evoked potential measures of IHTT accounted for significant variance in measures of reading and related cognitive skills. The implications of these data for understanding the underlying neural substrates of dyslexia are discussed.