title: Age-related differences in effective connectivity of brain regions involved in Japanese kanji processing with homophone judgment task.
abstract: Reading is a complex process involving neural networks in which connections may be influenced by task demands and other factors. We employed functional magnetic resonance imaging and dynamic causal modeling to examine age-related influences on left-hemispheric kanji reading networks. During a homophone judgment task, activation in the middle frontal gyrus, and dorsal and ventral inferior frontal gyri were identified, representing areas involved in orthographic, phonological, and semantic processing, respectively. The young adults showed a preference for a semantically-mediated pathway from orthographic inputs to the retrieval of phonological representations, whereas the elderly preferred a direct connection from orthographic inputs to phonological lexicons prior to the activation of semantic representations. These sequential pathways are in line with the lexical semantic and non-semantic routes in the dual-route cascaded model. The shift in reading pathways accompanied by slowed reaction time for the elderly might suggest age-related declines in the efficiency of network connectivity.
authors.affiliation: Division of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, Singapore.
authors.forename: Chiao-Yi
authors.initials: CY
authors.lastname: Wu
authors.affiliation: Division of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, Singapore.
authors.forename: Jia Ying Serene
authors.initials: JY
authors.lastname: Koh
authors.affiliation: Division of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, Singapore.
authors.forename: Moon-Ho Ringo
authors.initials: MH
authors.lastname: Ho
authors.affiliation: Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, United States; Neuroimaging and Informatics Lab, National Center for Geriatrics and Gerontology, Ohbu, Aichi, Japan; Japan Society for the Promotion of Sciences, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Miyakoshi
authors.affiliation: Neuroimaging and Informatics Lab, National Center for Geriatrics and Gerontology, Ohbu, Aichi, Japan.
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Nakai
authors.affiliation: Division of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, Singapore. Electronic address: annabelchen@ntu.edu.sg.
authors.forename: Shen-Hsing Annabel
authors.initials: SH
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D007564:Japan; D007600:Judgment / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D012660:Semantics; D055815:Young Adult
keywords: Aging; Dynamic causal modeling (DCM); Effective connectivity; Functional magnetic resonance imaging (fMRI); Kanji processing; Orthography; Phonology; Semantics