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Abstract:
t is postulated that the efficiency of frontal lobe function
decreases in normal aging. To assess the effects of aging on
working memory, behavioral and event-related brain potentials (ERP)
data were obtained from 12 young (22-29) and 12 old (69-79) adults
during a modified two-back task. A trial consisted of four separate
stimuli, the first two of which were the study set and the last two
the test set. Each stimulus could vary along two separate
dimensions (i.e., shape and position). For each of the two test
stimuli, subjects had to judge whether it shared the relevant
dimension, as specified by a cue, with the second to the last
stimulus. Working memory load was defined as the similarity between
the two study stimuli based on the relevant dimension. A secondary
memory load was added by manipulating the position of the cue
(i.e., before or after the study set). Although accuracy did not
significantly differ between groups, the old were significantly
slower in RT than the young. Furthermore, RT varied as a function
of load more for the old group than for the young. Preliminary ERP
data indicated a negative frontal component that was present only
in the young. Latency and scalp distribution varied as a function
of task and load in the young. Cue position effects at study were
most prominent at parietal electrodes in the old.
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