The locus of deficits in dysphonemic dyslexia: an ERP analysis

Abstract

Brain stem, middle auditory and auditory event-related potentials (ERPs) were recorded from a group of 13 dysphonemic dyslexic children and 10 matched normal controls. Auditory stimuli were used to elicit ERPs. The focus of our study was an ERP investigation of a slower auditory categorization, rather than simple detection, of pure tones. Brain stem and middle auditory evoked responses did not show any retardation in dyslexics compared with non-dyslexic children. When subjects performed a tone categorization task in which they were required to detect a rare tone interspersed in a series of frequent tones, dysphonemic dyslexics showed longer N2 latency. Compared with non-dyslexics, N2 delays were maximal over the left temporo-parietal r egion and bilaterally over the occipital sites. These areas have been postulated to be crucial in oral language and reading comprehension.