Testing Models of the Visual Word Form Area Using Combined ERP and fMRI Using the Special Properties of Chinese Characters

Abstract

The visual word form area or VWFA has been of special interest for studies of reading and dyslexia and yet there are conflicting models regarding its function. Here we put the Local Combination Detector, Lexicon, and Interactive accounts to the test, using a combination of event-related potentials and functional magnetic resonance imaging. We do so using both pseudoword and reversed radical false word manipulations with Chinese characters, making use of its special properties. We recorded event-related potentials with 68 channels while twenty native Chinese speakers were making rhyme and meaning judgments on single Chinese characters and BOLD signals were collected in a 3T magnet using multi-plane EPI with a further fifteen native Chinese speakers. The word N170 showed a prolongation for reversed radical false characters while the VWFA also showed an effect of reversal, albeit only for pseudocharacters. Furthermore, an N450 rhyming effect was observed in the phonological task compared to the semantic task, but only via an interaction with reversal. The source analysis of the N450 co-registered with a Supplementary Motor Area activation. The combination of these observations suggests that the ventral orthographic pathway is partially order insensitive and that full phonological encoding occurs relatively late, supporting and expanding a model of dyslexia. Overall, they best support a version of the Lexicon account of the VWFA.