Working Memory Training and Cortical Arousal in Healthy Older Adults: A Resting-State EEG Pilot Study

The current pilot study aimed to test the gains of working memory (WM) training, both at the short- and long-term, at a behavioral level, and by examining the electrophysiological changes induced by training in resting-state EEG activity among older adults. The study group included 24 older adults (from 64 to 75 years old) who were randomly assigned to a training group (TG) or an active control group (ACG) in a double-blind, repeated-measures experimental design in which open eyes, resting-state EEG recording, followed by a WM task, i.e., the Categorization Working Memory Span (CWMS) task, were collected before and after training, as well as at a 6-month follow-up session. At the behavioral level, medium to large Cohen's d effect sizes was found for the TG in immediate and long-term gains in the WM criterion task, as compared with small gains for the ACG. Regarding intrusion errors committed in the CWMS, an index of inhibitory control representing a transfer effect, results showed that medium to large effect sizes for immediate and long-term gains emerged for the TG, as compared to small effect sizes for the ACG. Spontaneous high-beta/alpha ratio analyses in four regions of interest (ROIs) revealed no pre-training group differences. Significantly greater TG anterior rates, particularly in the left ROI, were found after training, with frontal oscillatory responses being correlated with better post-training CWMS performance in only the TG. The follow-up analysis showed similar results, with greater anterior left high-beta/alpha rates among TG participants. Follow-up frontal high-beta/alpha rates in the right ROI were correlated with lower CWMS follow-up intrusion errors in only the TG. The present findings are further evidence of the efficacy of WM training in enhancing the cognitive functioning of older adults and their frontal oscillatory activity. Overall, these results suggested that WM training also can be a promising approach toward fostering the so-called functional cortical plasticity in aging.