期刊
HUMAN BRAIN MAPPING
卷 32, 期 6, 页码 947-961出版社
WILEY-BLACKWELL
DOI: 10.1002/hbm.21081
关键词
aging; caudate; fMRI; FMT; PET; AADC
资金
- National Institute on Aging [AG027984]
Age-related deficits have been demonstrated in working memory performance and in the dopamine system thought to support it. We performed positron emission tomography (PET) scans on 12 younger (mean 22.7 years) and 19 older (mean 65.8 years) adults using the radiotracer 6-[(18)F]-fluoro-L-m-tyrosine (FMT), which measures dopamine synthesis capacity. Subjects also underwent functional magnetic resonance imaging (fMRI) while performing a delayed recognition working memory task. We evaluated age-related fMRI activity differences and examined how they related to FMT signal variations in dorsal caudate within each age group. In posterior cingulate cortex and precuneus (PCC/Pc), older adults showed diminished fMRI deactivations during memory recognition compared with younger adults. Greater task-induced deactivation (in younger adults only) was associated both with higher FMT signal and with worse memory performance. Our results suggest that dopamine synthesis helps modulate default network activity in younger adults and that alterations to the dopamine system may contribute to age-related changes in working memory function. Hum Brain Mapp 32:947-961, 2011. (C) 2010 Wiley-Liss, Inc.
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