Deficits in Processing Characters in Chinese Developmental Dyslexia: Preliminary Results From Event-related Potentials and Time Frequency Analyses

Abstract

Individuals with dyslexia have deficiencies in lexical organization and processing that are behaviorally manifested as difficulties in learning grapheme-phoneme correspondences. The present study investigates the lexical representations of Chinese reading-impaired children using event-related potentials (ERP) and time-frequency analysis. Two Cantonese-speaking male children, one with reading impairment (PR) and one with normal reading performance (CA), performing a character recognition task were conducted. ERP results indicated that CA showed lexicality effect at N400 and N170 that was not evident in PR. The time-frequency analyses found greater event-related synchronization and phase coherence at theta band suggesting greater cognitive demand in processing pseudowords than real words for CA. Greater synchronization between cortical regions was also observed at the gamma band for pseudowords. These differences were not found for PR, suggesting that PR may have weaker lexical representations, resulting in inefficient orthographic processing and perhaps difficulties in accessing phonological and/or semantic information of known characters.