TitleNeural networks underlying language processing in same script bilinguals
NameBoukrina, Olga (author), Delgado, Mauricio (chair), Hanson, Stephen José (internal member), Hanson, Catherine (internal member), Austin, Jennifer (internal member), Williams, Edwin (outside member), Rutgers University, Graduate School - Newark,
DescriptionA small area in the inferior occipito-temporal cortex of the brain named the Visual Word Form Area (VWFA) was shown to be involved in recognition of written words. This area becomes more active when participants view written words as compared to other kinds of visual stimuli, such as checkerboard patterns (e.g., Cohen et al., 2000; 2002), digits (Polk et al., 2002), or geometric shapes (Gros et al., 2001). This dissertation research examined how functional specialization to written words emerges in the VWFA as a function of language experience and how the response in this area may rapidly adapt to the constraints imposed by the characteristics of the visual input. VWFA activity was measured with fMRI in two samples of same-script bilingual speakers, who varied in the level of proficiency across two languages. In Experiments 1 and 2, activity for first and second language words was contrasted with checkerboard pattern baseline. Both overlapping and distinct areas of activation within VWFA were found for each language. The extent of activation overlap for first and second language was related to participants' language proficiency and age of acquisition. This result was confirmed by univariate (Experiment 1) and multivariate (Experiment 2) analyses. In Experiment 3, repetition suppression was observed in the VWFA for word-pairs with similar orthography (homographs), but not for word-pairs with similar orthography and meaning (cognates), indicating that the VWFA is sensitive to semantic information. In addition, graphical connectivity analyses revealed that the more proficient language activated a ventral route from the VWFA to the prefrontal areas, and the less proficient language activated a dorsal route. Experiment 4 tested whether neural activity in the VWFA increases when target words are semantically congruent with the rest of the words in a sentence. The results showed that while the VWFA activity is buffered against repetition suppression by semantic similarity between single words, the VWFA is not sensitive to sentence level congruency. Collectively, the results suggest that the VWFA supports abstract orthographic processing, with similar mechanisms employed for early-acquired same-script languages, and that it participates in the integration of incoming visual information with single word semantics.
NoteIncludes bibliographical references
Noteby Olga Boukrina
CollectionGraduate School - Newark Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.