Abnormal pattern of cortical speech feature discrimination in 6-year-old children at risk for dyslexia.

The present study aimed to determine whether speech sound encoding and discrimination are affected in 6-year-old children having an elevated risk for dyslexia. Their event-related potentials (ERPs) for syllables and syllable changes critical in speech perception and language development (vowel, vowel-duration, consonant, frequency (F0), and intensity changes) were compared with those of children without a dyslexia risk. ERPs were recorded with a new linguistic multi-feature paradigm which enables one to assess the discrimination of five features in 20min. Also, an oddball condition with vowel and vowel-duration deviants was included. The amplitudes of the P1 response elicited by the standard stimuli were smaller in the at-risk group. Furthermore, the amplitudes of the mismatch negativity (MMN) were smaller for the vowel, vowel-duration, consonant, and intensity deviants in children at risk for dyslexia. These results are consistent with earlier studies reporting auditory processing difficulties in children at risk for dyslexia and diagnosed dyslexia. However, the current study, enabling the recording of MMN for multiple sound features, suggests the presence of wide-spread auditory difficulties in children at risk for dyslexia. Copyright 2010 Elsevier B.V. All rights reserved.