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P4‐019: Variability in Spatial Pattern Separation Performance in Memory Impaired and Unimpaired Older Adults
Author(s) -
Stark Shauna M.,
Yassa Micheal A.,
Stark Craig E.L.
Publication year - 2010
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2010.08.079
Subject(s) - audiology , psychology , hippocampus , young adult , age groups , developmental psychology , medicine , demography , neuroscience , sociology
Background: In this study, we sought to capitalize on the variability observed in the aging of both rats and humans in a study of spatial memory. Hunsaker et al. (2008) reported that when rats had a lesion to the dentate gyrus (DG) of the hippocampus, they were impaired in their ability to detect the metric change in object locations. Methods: We modified this design for humans by presenting pairs of pictures on a computer screen to healthy older (N1⁄4 21) and younger (N1⁄4 20) adults. Participants studied 10 pairs of pictures and were then tested on whether the same pairs were in the same or different locations compared to the study session, completing 10 blocks of 10 pairs of pictures total. Critically, for the different trials, only one picture of the pair changed location and it could be moved a small amount (close), a moderate amount (medium), or a large amount (far). Since we were interested in the variability associated with healthy aging, we divided the aging group into aged intact and aged impaired. Aged intact participants scored within the normal range for young individuals (ages 20-29) on the delayed test of the Rey Auditory Verbal Learning Test (RAVLT), whereas aged impaired individuals scoredmore than 1 standard deviation below these norms. Importantly, the aged impaired individuals scored within the normal range for their own age group (ages 60-80), so they were not clinically impaired, just impaired relative to the young. Results: We found that the aged intact group performed exactly the same as the young adults, with performance gradually increasing from the close to the far spatial distance. In contrast, the aged intact group performed significantly worse on the different conditions, but were not impaired when the pictures had not changed locations . In addition, there was a strong correlation between the aged impaired RAVLT scores and their performance on the different trials. Conclusions: These data indicate a shift away from pattern separation and toward pattern completion, consistent with rodent studies. The variability observed in memory performance in aging may be due to changes associated with the DG in aging.