Individual predictors and electrophysiological signatures of working memory enhancement in aging

A primary goal of translational neuroscience is to identify the neural mechanisms of age-related cognitive de-cline and develop protocols to maximally improve cognition. Here, we demonstrate how interventions that apply noninvasive neurostimulation to older adults improve working memory (WM). We found that one session of sham-controlled transcranial direct current stimulation (tDCS) selectively improved WM in older adults with more education, extending earlier work and underscoring the importance of identifying individual predictors of tDCS responsivity. Improvements in WM were associated with two distinct electrophysiological signatures. First, a broad enhancement of theta network synchrony tracked improvements in behavioral accuracy, with tDCS effects moderated by education level. Further analysis revealed that accuracy dynamics reflected an anterior-posterior network distribution regardless of cathode placement. Second, specific enhancements of theta-gamma phase-amplitude coupling (PAC) reflecting tDCS current flow tracked improvements in reaction time (RT). RT dynamics further explained inter-individual variability in WM improvement independent of education. These findings illuminate theta network synchrony and theta-gamma PAC as distinct but complementary mechanisms supporting WM in aging. Both mechanisms are amenable to intervention, the effectiveness of which can be pre-dicted by individual demographic factors.

Automated summary

The study suggests that applying noninvasive neurostimulation to older adults can improve their working memory. The effects of neurostimulation are influenced by education level and individual characteristics. Improvements in working memory are associated with specific changes in brain waves, providing theoretical support for enhancing cognitive ability in aging.