Visual information processing in dyslexic children

Objective: Several studies presented evidence for magnocellular deficits in dyslexics both in behavioural as well as in electrophysiological data of local electrode sites. We investigated two well-known paradigms (motion-onset and random-dot-kinematogram) with regard to global electrophysiological parameters. Methods: Twenty-one-channel event-related potentials (ERPs) of 16 dyslectic and 15 control children were analyzed with reference-independent methods. For each paradigm quasi stable microstates were identified by means of a data-driven segmentation procedure and compared between both groups. Results: Differences in global ERP responses between dyslexic and control children could be found for rapid moving gratings but not for the dot coherence. Conclusions: Dyslexic children seem to have some highly specific visual deficits in processing moving stimuli. These deficits can be related to the magnocellular system. (C) 2004 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.