Poster B73, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Linguistic and Non-Linguistic Semantic Processing in Individuals with Autism Spectrum Disorders: An ERP Study
Emily Coderre1, Mariya Chernenok1,2, Barry Gordon1,3, Kerry Ledoux1; 1Cognitive Neurology/Neuropsychology, Department of Neurology, The Johns Hopkins University School of Medicine, 2Center for Mind and Brain, University of California, Davis, 3Department of Cognitive Science, The Johns Hopkins University
Individuals with autism spectrum disorders (ASD) experience difficulties with language, particularly with higher-level functions such as semantic integration. Some studies have suggested that this semantic integration deficit is specific to language. However, this appearance of specificity may have been caused by the use of cross-modal stimuli to compare linguistic and non-linguistic semantic processing. Using a semantic priming task with EEG, we compared within-modality lexico-semantic processing (pairs of written words) and visuo-semantic processing (pairs of pictures) in adults with ASD and adults with typical development (TD). Both groups showed an N400 effect (i.e. larger negative amplitude for unrelated than related stimulus pairs) in response to picture pairs, indicating intact visuo-semantic processing in the ASD group, as predicted. However, in contrast to previous studies, the ASD group also showed successful lexico-semantic processing, with similar N400 effects between groups for word stimuli. Nonetheless, subtle differences in the timing and topography of the N400 effect suggested different lexico-semantic processing mechanisms between groups. Specifically, an earlier frontal negativity, interpreted as an N300, was observed for the TD group while a later right-lateralized parietal N400 effect, interpreted as an N400RP, was observed for the ASD group. The N300 has been attributed to expectancy-based processes in semantic priming, while the N400RP has been attributed to semantic matching and more strategic processes of post-lexical semantic integration. These findings suggest that the two groups used different strategies to achieve successful lexico-semantic processing: an expectancy-based strategy for the TD group and a controlled post-lexical integration strategy for the ASD group.
Topic Area: LANGUAGE: Semantic