title: Inter- and intrahemispheric connectivity differences when reading Japanese Kanji and Hiragana.
abstract: Unlike most languages that are written using a single script, Japanese uses multiple scripts including morphographic Kanji and syllabographic Hiragana and Katakana. Here, we used functional magnetic resonance imaging with dynamic causal modeling to investigate competing theories regarding the neural processing of Kanji and Hiragana during a visual lexical decision task. First, a bilateral model investigated interhemispheric connectivity between ventral occipito-temporal (vOT) cortex and Broca's area ("pars opercularis"). We found that Kanji significantly increased the connection strength from right-to-left vOT. This is interpreted in terms of increased right vOT activity for visually complex Kanji being integrated into the left (i.e. language dominant) hemisphere. Secondly, we used a unilateral left hemisphere model to test whether Kanji and Hiragana rely preferentially on ventral and dorsal paths, respectively, that is, they have different intrahemispheric functional connectivity profiles. Consistent with this hypothesis, we found that Kanji increased connectivity within the ventral path (V1 ↔ vOT ↔ Broca's area), and that Hiragana increased connectivity within the dorsal path (V1 ↔ supramarginal gyrus ↔ Broca's area). Overall, the results illustrate how the differential processing demands of Kanji and Hiragana influence both inter- and intrahemispheric interactions.
authors: Wellcome Trust Centre for Neuroimaging.
authors: Keith J
authors: KJ
authors: Kawabata Duncan
authors: Tae
authors: T
authors: Twomey
authors: 'Ōiwi
authors: '
authors: Parker Jones
authors: Mohamed L
authors: ML
authors: Seghier
authors: Tomoki
authors: T
authors: Haji
authors: Katsuyuki
authors: K
authors: Sakai
authors: Cathy J
authors: CJ
authors: Price
authors: Joseph T
authors: JT
authors: Devlin
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D032882:Comprehension / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007564:Japan; D007802:Language; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009434:Neural Pathways / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011932:Reading; D012815:Signal Processing, Computer-Assisted; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: dynamic causal modeling; functional connectivity; logograph; reading; visual word recognition
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