| |
Abstract:
Abstract: To determine how normal aging affects the
neurocognitive processes involved with spatial working memory (WM),
we recorded multi-channel EEG from high functioning, healthy adults
during the performance of easy and difficult versions of an n-back
WM task. Three age groups (younger mean=22yrs; middle-aged
mean=48yrs; older mean=69yrs; n=10 each) were matched for IQ (mean
IQ 123) and practiced in task performance. Older subjects had
slower responses than younger subjects, particularly in the more
difficult task. Accuracy did not significantly differ. Several
age-related evoked potential differences were observed: The visual
N1 and P3 decreased in amplitude and increased in latency as a
function of age. Older subjects did not show the parietal maximum
that was characteristic of the younger subjects' P3. Older subjects
also showed a larger and more frontally distributed P2 than did the
younger subjects. In the task-related EEG, older subjects showed
larger and topographically more widespread alpha-band EEG
suppression with increased task difficulty than did the young
adults. These results suggest that age can affect stages of task
processing that span from perceptual processing to response
execution. Since alpha amplitude is inversely related to the
proportion of neurons activated by a task, the results also suggest
that older subjects attempt to compensate for age-related changes
by exerting extra effort during task performance. Supported by NIMH
& NASA.
|
