Impaired visual expertise for print in French adults with dyslexia as shown by N170 tuning

Abstract

Efficient reading relies on expertise in the visual word form area, with abnormalities in the functional specialization of this area observed in individuals with developmental dyslexia. We have investigated event related potentials in print tuning in adults with dyslexia, based on their N170 response at 135–255ms. Control and dyslexic adults performed a lexical decision task with symbol strings and four sets of word-like stimuli (consonant strings, pseudowords, low frequency words and high frequency words). N170 tuning was observed in the control group, with larger left occipito-temporal negativities for word-like stimuli than for symbol strings. In contrast, N170 specialization was lacking in dyslexics, suggesting no visual expertise for print. Moreover, behavioral data indicated that adults with dyslexia had longer latencies and more errors for pseudowords than for other stimuli, suggesting a persistent phonological deficit in these individuals. These findings suggest that altered decoding abilities may disrupt perceptual expertise for print. The results are discussed in the context of the phonological mapping deficit theory.