Correlations of striatal dopamine synthesis with default network deactivations during working memory in younger adults

• Published in: Human brain mapping 2011-06, Vol.32 (6), p.947-961
• Main Authors: Braskie, Meredith N., Landau, Susan M., Wilcox, Claire E., Taylor, Stephanie D., O'Neil, James P., Baker, Suzanne L., Madison, Cindee M., Jagust, William J.
• Format: Article
• Language: English
• Subjects: AADC; Aged; Aged, 80 and over; aging; Aging - physiology; Biological and medical sciences; Brain Mapping; caudate; Corpus Striatum - diagnostic imaging; Corpus Striatum - metabolism; Dopamine - biosynthesis; Fluorine Radioisotopes; fMRI; FMT; Fundamental and applied biological sciences. Psychology; Human; Humans; Image Interpretation, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Learning. Memory; Magnetic Resonance Imaging; Medical sciences; Memory; Memory, Short-Term - physiology; Middle Aged; Nervous system; PET; Positron-Emission Tomography; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Radiopharmaceuticals; Tyrosine - analogs & derivatives; Young Adult
• ISSN: 1065-9471; 1097-0193; 1097-0193
• DOI: 10.1002/hbm.21081

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‐[18F]‐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, 2011. © 2010 Wiley‐Liss, Inc.