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Zhiheng Zhou, Carol Whitney, Lars Strother; Hemifield-dependent fMRI repetition enhancement for word pairs with concomitantly repeated and added letters. Journal of Vision 2017;17(10):1042. doi: 10.1167/17.10.1042.
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Results from fMRI repetition studies of whole-word representation implicate a visual word form area (VWFA) in left occipitotemporal cortex. We used a rapid event-related fMRI partial word repetition paradigm to study the effects of repeating all letters of a word and concomitantly adding a letter, either at the end of the word or at the beginning (e.g. CAR → CART or CAR → SCAR), as compared to words that changed in full (e.g. CAR → DESK); we also varied the hemifield location of words within a pair, which either matched or not. Our main goal was to identify voxels showing repetition suppression for repeated letters in the context of a change in the meaning of a word. Results of previous studies (Strother et al. 2016; Glezer et al. 2009) led us to expect repetition suppression in an occipital word form area (OWFA), and possibly portions of retinotopic visual cortex, but not in the VWFA. Surprisingly, we observed little if any evidence of repetition suppression in any of our targeted cortical regions. We instead observed a single consistent locus of "repetition enhancement"—the VWFA—for partially repeated word pairs relative to fully changing words, even when each word within an event pair was viewed in an opposite visual hemifield. The sole exception to this effect was observed for word pairs in which both words appeared in the left visual hemifield. Our results suggest reactivation of letters shared between two words when these letters represent a real word, but only when at least one of the words appears in the right visual field, contralateral to the VWFA. We interpret our results in relation to the interhemispheric transfer of visual word form information and whole-word representation in the VWFA.
Meeting abstract presented at VSS 2017
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