Age-related differences in effective connectivity of brain regions involved in Japanese kanji processing with homophone judgment task

• Published in: Brain and language Vol. 135; pp. 32 - 41
• Main Authors: Wu, Chiao-Yi, Koh, Jia Ying Serene, Ho, Moon-Ho Ringo, Miyakoshi, Makoto, Nakai, Toshiharu, Chen, Shen-Hsing Annabel
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.08.2014; Elsevier
• Subjects: Adult; Adult. Elderly; Aged; Aging; Aging - physiology; Anatomical correlates of behavior; Behavioral psychophysiology; Biological and medical sciences; Brain - physiology; Brain Mapping; Developmental psychology; Dynamic causal modeling (DCM); Effective connectivity; Female; Frontal Lobe - physiology; Functional magnetic resonance imaging (fMRI); Fundamental and applied biological sciences. Psychology; Humans; Japan; Judgment - physiology; Kanji processing; Magnetic Resonance Imaging; Male; Middle Aged; Models, Neurological; Nerve Net - physiology; Orthography; Phonology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reaction Time - physiology; Reading; Semantics; Young Adult; Japan; Kanji processing; Semantics; Aging; Phonology; Dynamic causal modeling (DCM); Functional magnetic resonance imaging (fMRI); Orthography; Effective connectivity; Human; Senescence; Central nervous system; Cognition; Homophone; Experimental study; Japanese; Encephalon; Language; Young adult; Functional magnetic resonance imaging; Causality; Dynamic model; Elderly; Age; Judgment
• ISSN: 0093-934X; 1090-2155
• DOI: 10.1016/j.bandl.2014.04.005

•DCM was applied to examine kanji reading networks in the young and the elderly.•Differential pathways were selected for each group in a homophone judgment task.•The selected pathways resemble the lexical routes in the dual-route cascaded model.•Shift in pathways suggests age-related alterations in network connectivity.•With slower responses, the elderly may have reduced efficiency in connectivity. 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.