title: On the origin of the N400 effects: an ERP waveform and source localization analysis in three matching tasks.
abstract: The question of the cognitive nature and the cerebral origins of the event-related potential (ERP) N400 component has frequently been debated. Here, the N400 effects were analyzed in three tasks. In the semantic task, subjects decided whether sequentially presented word pairs were semantically related or unrelated. In the phonologic (rhyme detection) task, they decided if words were phonologically related or not. In the image categorization task, they decided whether images were categorically related or not. Difference waves between ERPs to unrelated and related conditions (defined here as the N400 effect) demonstrated a greater amplitude and an earlier peak latency effect in the image than in semantic and phonologic tasks. In contrast, spatial correlation analysis revealed that the maps computed during the peak of the N400 effects were highly correlated. Source localization computed from these maps showed the involvement in all tasks of the middle/superior temporal gyrus. Our results suggest that these qualitatively similar N400 effects index the same cognitive content despite differences in the representational formats (words vs. images) and the types of mismatch (semantic vs. phonological) across tasks.
authors.affiliation: The Edmond J. Safra Brain Research Center for the Study of Learning Disabilities and the Department of Learning Disabilities, Faculty of Education, University of Haifa, Mount Carmel, Haifa, 31905, Israel. akhateb@construct.haifa.ac.il
authors.forename: Asaid
authors.initials: A
authors.lastname: Khateb
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Pegna
authors.forename: Theodor
authors.initials: T
authors.lastname: Landis
authors.forename: Michaël S
authors.initials: MS
authors.lastname: Mouthon
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Annoni
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004192:Discrimination, Psychological; D004569:Electroencephalography / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007206:Individuality; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D009716:Numerical Analysis, Computer-Assisted; D010700:Phonetics; D012660:Semantics; D055815:Young Adult