Local Increase of Sleep Slow Wave Activity after Three Weeks of Working Memory Training in Children and Adolescents

Study Objectives: Evidence is accumulating that electroencephalographic (EEG) sleep slow wave activity (SWA), the key characteristic of deep sleep, is regulated not only globally, but also locally. Several studies have shown local learning- and use-dependent changes in SWA. In vitro and in vivo animal experiments and studies in humans indicate that these local changes in SWA reflect synaptic plasticity. During maturation, when synaptic changes are most prominent, learning is of utmost importance. Thus, in this study, we aimed to examine whether intensive working memory training for 3 w would lead to a local increase of sleep SWA using high-density EEG recordings in children and young adolescents. Setting: Sleep laboratory at the University Children's Hospital Zurich. Participants: Fourteen healthy subjects between 10 and 16 y. Interventions: Three weeks of intensive working memory training. Measurements and Results: After intensive working memory training, sleep SWA was increased in a small left frontoparietal cluster (11.06 +/- 1.24%, mean +/- standard error of the mean). In addition, the local increase correlated positively with increased working memory performance assessed immediately (r = 0.66) and 2 to 5 mo (r = 0.68) after the training. Conclusions: The increase in slow wave activity (SWA) correlates with cognitive training-induced plasticity in a region known to be involved in working memory performance. Thus, in future, the mapping of sleep SWA may be used to longitudinally monitor the effects of working memory training in children and adolescents with working memory deficiencies.