Resting-state microstate dynamics predict behavioral and neural efficiency during working memory processing in healthy aging
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Working memory performance declines with age, yet substantial variability exists among cognitively healthy older adults. Although task-evoked electrophysiological responses such as the P300b are sensitive to working memory load, it remains unclear how they relate to stable characteristics of intrinsic brain organization and individual differences in working memory performance. We combined resting-state and task-based electroencephalography (EEG) to examine relationships among working memory performance, P300b amplitude, and resting-state microstate dynamics in 33 cognitively healthy older adults. Participants completed an eyes-closed resting-state recording followed by a visual 0-, 1-, and 2-back task. Behavioral performance (d’), target-evoked P300b amplitude, and canonical resting-state microstate parameters were quantified using linear mixed-effects models. Increasing working memory load produced significant reductions in both discrimination performance and P300b amplitude, confirming expected behavioral and neural modulation. However, load-related changes in P300b amplitude were not associated with behavioral modulation, and neither was absolute P300b amplitude. Resting-state microstate dynamics selectively predicted task outcomes. In particular, longer duration of microstate D was associated with poorer behavioral discrimination performance. Longer duration of microstate C, in contrast was not associated with task outcomes but with larger P300b amplitude. These findings suggest that although behavioral performance and P300b amplitude reflect common neural responses to increasing working memory demands, stable characteristics of intrinsic brain organization account for meaningful individual differences in neural responsiveness and cognitive performance. Resting-state EEG microstates may therefore provide complementary, perhaps highly sensitive biomarkers of cognitive functioning beyond conventional task-evoked measures in healthy aging.
