In sum, our results suggest that (a) healthy aging is accompanied by a widespread decrease in slow wave power and worse performance on various cognitive tests; this phenomenon could underlie decreased synaptic plasticity and communication between functional networks, associated with impaired cognitive function, (b) for healthy older adults who are able to maintain relatively higher levels of resting slow wave power, improved performance is observed in tests assessing perceptual speed, working memory and executive functioning. This conclusion is consistent with numerous studies which implicate slow wave oscillations in critical cognitive functions, including speech perception, working memory, perceptual decision making, executive functioning as well as in facilitating interaction and coordinating different brain regions into functional networks27404142434445. It is also in line with recent proposals which consider slow wave activity as a neural correlate of enhanced control engagement, structuring and integrating the dynamics of neuronal communication in order to effectively adapt to current behavioral demands42 and which can be used to predict individuals who are more able to benefit from cognitive training regimes and show broad-based transfer effects to untrained cognitive control tasks4041.
