Aging and recognition memory: changes in regional cerebral blood flow associated with components of reaction time distributions.
Journal Article
We used H(2)15O positron emission tomography (PET) to measure age-related changes in regional cerebral blood flow (rCBF) during a verbal recognition memory task. Twelve young adults (20 to 29 years) and 12 older adults (62 to 79 years) participated. Separate PET scans were conducted during Encoding, Baseline, and Retrieval conditions. Each of the conditions involved viewing a series of 64 words and making a two-choice response manually. The complete reaction time (RT) distributions in each task condition were characterized in terms of an ex-Gaussian model (convolution of exponential and Gaussian functions). Parameter estimates were obtained for the mean of the exponential component (tau), representing a task-specific decision process and the mean of the Gaussian component (mu) representing residual sensory coding and response processes. Independently of age group, both tau and mu were higher in the Encoding and Retrieval conditions than in the Baseline condition, and tau was higher during Retrieval than during Encoding. Age-related slowing in task performance was evident primarily in mu. For young adults, rCBF activation in the right prefrontal cortex, in the Retrieval condition, was correlated positively with mu but not with tau. For older adults, rCBF changes (both increases and decreases) in several cortical regions were correlated with both mu and tau. The data suggest that the attentional demands of this task are relatively greater for older adults and consequently lead to the recruitment of additional neural systems during task performance.
Full Text
Duke Authors
Cited Authors
- Madden, DJ; Gottlob, LR; Denny, LL; Turkington, TG; Provenzale, JM; Hawk, TC; Coleman, RE
Published Date
- September 1999
Published In
Volume / Issue
- 11 / 5
Start / End Page
- 511 - 520
PubMed ID
- 10511640
Pubmed Central ID
- 10511640
International Standard Serial Number (ISSN)
- 0898-929X
Digital Object Identifier (DOI)
- 10.1162/089892999563571
Language
- eng
Conference Location
- United States