| Co-Investigator(Kenkyū-buntansha) |
ISHII Kenji Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human Welfare, Tokyo Metropolitan Institute of Gerontology, Language, Positron Medical Clinic, MD, Head, 福祉振興財団・東京都老人総合研究所, 副参事研究員 (10231135)
FUSHIMI Takao Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human Welfare, Tokyo Metropolitan Institute of Gerontology, Language, Cognition and Brain Science Research Group, PhD, Research Scientist, 福祉振興財団・東京都老人総合研究所, 研究員 (60260303)
SAKUMA Naoko Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human Welfare, Tokyo Metropolitan Institute of Gerontology, Language, Cognition and Brain Science Research Group, PhD, Research Assistant, 福祉振興財団・東京都老人総合研究所, 研究助手 (70152163)
IJUIN Mutsuo Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human Welfare, Tokyo Metropolitan Institute of Gerontology, Language, Cognition and Brain Science Research Group, PhD, Research Scientist, 福祉振興財団・東京都老人総合研究所, 研究員 (00250192)
KURETA Yoich Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human Welfare, Tokyo Metropolitan Institute of Gerontology, Language, Cognition and Brain Science Research Group, PhD, Research Scientist, 福祉振興財団・東京都老人総合研究所, 研究員 (60321874)
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| Research Abstract |
It is often said that while aging increases vocabulary, retrieval of words, especially proper names such as person's names, becomes difficult with increasing age. Indeed, our past research on word retrieval (verbal fluency task) revealed that the retrieval performance of elderly people was approximately 75 % of younger students for words representing animate (e.g., mammals, fishes, etc.) or inanimate (vehicles, tools, etc.), and only 55 % for proper names (names of politicians, actresses, etc).
In this project we did a PET activation study in which brain regions activated during verbal fluency tasks for semantic categories like animates, inanimate and proper names of famous persons, as well as phonological categories (retrieving words beginning with a pre-specified syllable) were explored. We found that in young normal subjects verbal fluency for animates, inanimate and phonological cues activated areas including inferoposterior region of the left temporal gyrus (BA 20,37) to a temporop
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arietal junction, and the left inferior frontal gyrus (BA44,45). Whereas the left temporal gyrus was interpreted to process word semantics, the left frontal gyrus was interpreted to play a role in selecting an appropriate word based on semantic and phonological information. In proper name retrieval, more rostal areas were activated, i.e., the anterior region of the left temporal cortex (BA22,38), and a region including the frontal pole and medial frontal cortex (BA10), the former associating deep semantic processing and the latter more controlled processing of word selection.
We also observed activated areas during verbal fluency for semantic categories (inanimate and proper names) and phonological cues in aged people, and found almost the same areas are activated, but their volumes tend to be smaller.
Recently, some researchers report that activated areas during language tasks like reading aloud words are different in elderly and young subjects, reflecting differential word or sentence processing in the two groups. However, atrophy of the brain grows with increasing age, and influence of atrophy on language and cognition has not been elucidated. We examined age-related brain shrinkage using a software called VBM(Voxel Based Morphometry) based on MRI brain images of 77 young and 23 old people. It was found that the normal elderly did not show a uniform atrophy regardless of the brain region, rather they showed restricted atrophy in a region surrounding the Syrvian fissure, inferior frontal to inferior parietal region, anteromedial frontal area of both hemispheres, and superior cerebellum. It was found that the left inferoposterior temporal gyrus is an only region that does not overlap with the age-related shrinkage, suggesting that deficient verbal fluency in the elderly is attributable at least in part to brain atrophy. Less
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