title: Altered hemispheric asymmetry during word processing in dyslexic children: an event-related potential study.
abstract: The present event-related potential study aimed at finding neurophysiological correlates of inadequate reading performances in developmental dyslexia. By using the same set of words in different linguistic tasks, we found variations of cortical asymmetry between dyslexic individuals and controls starting with the N420, a component supposed to index the phonological processing during reading. Whereas in controls this component was left lateralized, in disabled readers it was more distributed across hemispheres. The observed lack of lateralization in dyslexic individuals was also found in the later slow negative wave that developed in the 700 to 1500-ms time interval. We postulate that the altered asymmetry is related to an impairment of the grapheme-phoneme conversion mechanism. The findings would therefore support the hypothesis of a phonological deficit underlying this learning disability.
authors.affiliation: Department of General Psychology, University of Padova, Padova, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Penolazzi
authors.forename: Chiara
authors.initials: C
authors.lastname: Spironelli
authors.forename: Claudio
authors.initials: C
authors.lastname: Vio
authors.forename: Alessandro
authors.initials: A
authors.lastname: Angrilli
mesh_terms: D000293:Adolescent; D002540:Cerebral Cortex / Q000502:physiology*; D002648:Child; D004410:Dyslexia / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D007807:Language Tests; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D014705:Verbal Behavior / Q000502:physiology*