Comparative electrophysiological study of word reading in French: does the P1-N1 temporal window reveal a neurodevelopmental anomaly?

International audience; Background: Event-Related Potentials (ERPs) permit to study neuronal specialization during reading acquisition. The N170 wave was previously shown to be a surrogate of the fine tuning of reading in adults and adolescents as well. Aim: We analyzed and described the variations of the N170 wave as a function of French words with visual or phonetical similarities in 12 to 14 yearold dyslexic patients. We tested the validity and modulation of this effect by comparing different populations of normal and dyslexic patients of various severity. Methods: ERPs were recorded in seventeen dyslexic children with the same method as in normative populations in lexical decision. Stimuli consisted of frequent words chosen on the basis of near or far visemes and morphemes. Dyslexic children were compared to two control (i.e. normal readers) groups, one group of the same age (N=15) and one group of adults (N=17). N170 and P100 waves were analyzed, as well as interactions between both (i.e. P1N1) searched. Psychometric and language tests were also performed. Results were analyzed by ANOVA. Results: The results of sixteen patients are presented. All sixteen showed significant differences on all psycholinguistic items when compared to the two control groups. All groups (patients and controls) significantly differed from each other for all tests (F'(4;42)=119, 2; p