Pre-attentive processing of auditory patterns in dyslexic human subjects

It has been hypothesized that auditory temporal processing plays a major ro le in the aetiology of dyslexia. Event-related brain potentials (mismatch n egativity, MMN) of auditory temporal processing were assessed in 15 dyslect ic adults and 20 controls. A complex tonal pattern was used where the diffe rence between standard and deviant stimuli was the temporal, not the freque ncy structure. Dyslexics had a significantly smaller MMN in the time window of 225-600 ms. This result shows that dyslexics have a significant pre-att entive deficit in processing of rapid temporal patterns suggesting that it may be the temporal information embedded in speech sounds, rather than phon etic information per se, that resulted in the attenuated MMN found in dysle xics in previous studies. MMN scalp topographies were similar for both grou ps, showing a maximum over fronto-central leads. (C) 1999 Elsevier Science ireland Ltd. All rights reserved.