RECENT PRESENTATIONS

McEvoy, L K., Pellouchoud, E., Smith, M.E., Gevins, A. (2000). Neurophysiological Signals of Working Memory in Normal Aging. Annual Meeting of the Society for Neuroscience. November, New Orleans.

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.