Changes in the density of stage 2 sleep spindles following motor learning in young and older adults

Abstract

SUMMAR Y The purpose of this study was to compare the changes that occur in sleep architecture following the acquisition of a simple motor learning task in young and older adults. Subjects included 14 young (range = 17-24 years) and 14 older (range = 62-79 years) adults, all of whom were in good health. Using in-home recording systems, sleep architecture (sleep stages and the density of Stage 2 sleep spindles) was examined before and after learning the pursuit rotor. To control for possible age differences in baseline motor performance and spindle density, both absolute and relative (percent change) measures were examined. Both groups improved significantly on the pursuit rotor task at Retest (1 week later); however, the magnitude of absolute improvement was larger in the young group than in the older group. There was no group difference when a relative measure of improvement (percent increase across sessions) was used. The density of Stage 2 sleep spindles increased significantly following task Acquisition in the young group but not in the older group. These age differences failed to reach significance when change was measured as a percentage of baseline level of spindle density. The increase in spindle density was correlated with performance level during acquisition in the young group but not the older group. The results of the present study are largely consistent with previous studies on sleep and memory in young adults and suggest that more detailed examination of this relationship in older adults is warranted.k e y w o r d s aging, consolidation, motor learning, non-rapid eye movement sleep, procedural learning, stage 2 sleep spindle

Slow wave sleep and REM sleep awakenings do not affect sleep dependent memory consolidation

“…58 Given the lack of effect in our study between the amounts of SWS, REM sleep, and delta power on learning tasks, we then analyzed the spindle measures, which were unchanged in all our conditions and which are often associated with memory consolidation. [35][36][37][38][39][40][41][42][43][44] In the undisturbed condition, we found a significant correlation between the declarative task and the spindle measures in stage 2 and NREM: absolute spindle activity and spindle density. This correlation is particularly strong when considering only the absolute spindle activity and spindle density in stage 2 in the first third of the night.…”

“…2,18,47 Recently, further correlations have been found between the overnight enhancement of simple motor tasks and stage 2 spindle density, as well as an increase of stage 2 spindle density after motor learning. 38,39,[41][42][43] We explore the evidence for this effect in our study at the end of this section.…”

“…Since sleep spindles have often been correlated with memory consolidation, [35][36][37][38][39][40][41][42][43][44] we performed a bivariate Pearson correlation between the declarative consolidation (dcons) and the stage 2 and NREM spindle measures (SpD and aSpA), as well as between the motor consolidation (mcons) and the spindle measures. If a significant correlation was found, we carried out further correlations with aSpA and SpD of the thirds of the night.…”

Association of salivary-assessed oxytocin and cortisol levels with time of night and sleep stage

“…This study is relevant to proposals for mnemonic consolidation functions of REM sleep and of N2, in that it indicates that during the later part of sleep CT is as high in N2 as it is in REM. If REM memory-consolidation processes late in sleep are subject to increased CT levels at that time, as proposed by Payne and Nadel (2004), Wagner and Born (2008) and Payne (2010), then N2 memory-consolidation mechanisms (Peters et al 2008;Fogel and Smith 2010) may be subject to the same cortisol-induced processes. Cortisol can have a disruptive effect on learning and memory (e.g.…”

Cognitive training improves sleep quality and cognitive function among older adults with insomnia

“…Evidence from studies in younger and older populations without insomnia suggests that sleep architecture changes as a result of learning. Following learning, young adults exhibit an increase in proportion of REM sleep [58]; an increase in number of REMs and in REM density [59], [60]; an increase in duration of Stage 2 sleep, in the number of sleep spindles and in spindle density [60][61][62][63][64][65]; and an increases in slow-wave activity (SWA) [66], while older adults display an increase in number of minutes in SWS and in SWS percentage [61]. Yet to the best of our knowledge, no research has examined the beneficial effects of learning on sleep structure and cognitive function among older adults suffering from insomnia.…”