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

International Standard Serial Number (ISSN)

  • 0898-929X

Language

  • eng

Conference Location

  • United States