Functional Role of NREM sleep oscillations in aging

衰老与睡眠的重要改变有关，包括睡眠时间变短、睡眠变浅以及特定脑电波（或大脑活动的振荡）如慢波和纺锤波的减少。陈述性记忆巩固的特定组成部分（即明确回忆事实和事件的能力）也随着正常年龄的增长而显著下降。重要的是，慢波和纺锤波在睡眠中强化大脑记忆痕迹方面发挥着重要作用。这项研究计划的长期目标是了解睡眠振荡在衰老中的功能作用。具体来说，我们将使用多模态方法来检验睡眠振荡中与年龄相关的变化与大脑增强陈述性记忆能力的变化有关的假设。我们的第一个具体目标是定位皮层同步活动，并评估在学习陈述性记忆任务后，这些皮层区域如何在睡眠振荡期间相互沟通。我们预测，与控制任务相比，在学习后，睡眠振荡期间的同步性将从更广泛、更紧密的皮层区域中出现。我们还预计，这些影响在年龄较大的参与者中不那么明显，并且在早晨保持陈述性记忆任务的表现将与睡眠振荡期间增强的皮层通信有关。我们的第二个具体目标是评估在头皮特定区域诱导弱电流的效果，以诱导睡眠振荡并增强年轻和老年参与者在陈述性记忆任务中的保留。我们预测，与控制条件相比，年轻人的睡眠振荡会增强，尤其是老年参与者，这将提高对陈述性记忆任务的保留。该研究项目将提供关键的知识，以了解与年龄相关的睡眠振荡变化如何与大脑可塑性的变化相关联。诱发睡眠振荡的方法的发展为评估睡眠振荡的作用提供了一种创新的因果方法。在NSERC授权的精神下，这项研究计划还将促进新方法（电磁神经成像）和先进技术设备（基于波的神经刺激）的发展。总体目标是在睡眠振荡异常的特定人群（如轻度认知障碍和帕金森病）中增强睡眠期间大脑的可塑性。

Aging is associated with important modifications in sleep including shorter sleep duration, shallower sleep and reductions in specific brain waves (or oscillations of the brain activity) such as slow-waves and spindles. Specific components of declarative memory consolidation (i.e. ability to recall explicitly facts and events) also decline significantly with normal aging. Importantly, slow-waves and spindles play an important role in reinforcing cerebral memory traces during sleep. The long-term objective of this research program is to understand the functional role of sleep oscillations in aging. Specifically, we will use a multi-modal approach to test the hypothesis that age-related changes in sleep oscillations are associated with changes in the ability of the brain to strengthen declarative memory. Our first specific objective is to localize on the cortex synchronous activity and evaluate how these cortical areas communicate together during sleep oscillations after learning a declarative memory task in young and older participants. We predict that synchrony during sleep oscillations will emerge from a broader and more connected set of cortical regions after learning, as compared to the control task. We also expect that these effects will be less pronounced in older participants and that performance on the retention of a declarative memory task in the morning will be associated to enhanced cortical communication during sleep oscillations. Our second specific objective is to evaluate the effects of inducing weak electric currents on specific areas on the scalp to induce sleep oscillations and enhance retention on a declarative memory task in young and older participants. We predict that compared to a control condition, sleep oscillations will be enhanced in the young and, in particular, in the older participants, which will improve the retention on a declarative memory task. The research program will provide crucial knowledge as to how age-related changes in sleep oscillations are associated with changes in brain plasticity. The development of a methodology to induce sleep oscillations provides an innovative causal approach to assess the role of sleep oscillations. In the spirit of the NSERC mandate, this research program will also stimulate the development of new methodology (electromagnetic neuroimaging) and advanced technological devices (wave-based neurostimulation). The overall objective is the enhancement of brain plasticity during sleep in specific populations which show sleep oscillations abnormalities (e.g. mild cognitive impairment and Parkinson disease).