Impact of sleep-wake circuits on cortical synapse plasticity during motor learning

摘要 我们仍然想知道我们为什么睡觉。我们至少知道睡眠有助于我们的记忆。几乎每一个阶段， 睡眠的特征涉及记忆巩固，包括非快速眼动慢波睡眠 (NREM SWS）、NREM纺锤波、REM θ节律和睡眠结构连续性。破坏这些 在所有影响记忆的神经障碍中发现了阶段和特征（Angelman，Autisspectrum， 酒精中毒、阿尔茨海默氏症、脆性X染色体、亨廷顿氏症、帕金森氏症、Rett氏症等）。支持的机制 人们对这些记忆缺陷知之甚少，睡眠在突触中的作用仍有很大争议。 突触是支撑记忆和认知的中心生理结构，但每个突触是如何睡眠的呢？ 阶段和特点重塑突触仍不清楚。NREM SWS和总睡眠与 一般来说，突触缩小，但NREM和纺锤体也参与突触加强; 类似地，REM与突触修剪和维持两者相关联。一个主要的障碍， 研究表明，睡眠阶段和特征都是相互联系和综合的。破坏一个 通常会影响其他阶段/特征与特定突触功能之间的关联 挑战性通过对神经元回路进行精确的光遗传学控制，我们已经克服了这一障碍。睡眠 连续性和记忆巩固可以在不改变整体睡眠结构的情况下被中断， 通过使用下丘脑泌素神经元刺激（Aim 1）每60秒引入微觉醒（<2秒）来测量量。 刺激丘脑网状神经元可诱发NREM睡眠纺锤波和记忆巩固 不影响睡眠（目标2）。θ节律和记忆巩固可以被沉默破坏 内侧隔GABA神经元在REM发作期间仅不影响睡眠结构的完整性（目的3）。 我们将在皮层运动学习任务后操纵这三个睡眠特征， 运动皮层的突触形成这些新形成的突触和它们的邻居的重塑将 使用最先进的体内（双光子）和离体（阵列断层扫描）突触显微镜进行跟踪。 而前者的纵向分析将揭示导致记忆编码的脊柱动力学 巩固，后者的全球突触分析将揭示如何突触类（抑制性，兴奋性）， 突触群体（取决于层）和它们的突触下分子成分被重塑， 睡眠连续性（目标1）、纺锤波（目标2）和快速眼动（目标3）。光遗传学的具体用途是 操纵不同的睡眠阶段作为突触动力学研究是前所未有的， 阐明睡眠连续性、NREM纺锤波和REM如何各自影响皮层突触可塑性 支持运动学习后的记忆巩固这些发现对未来的战略至关重要， 恢复和治疗神经发育和神经退行性疾病中的记忆和认知缺陷。

Abstract We still wonder why we sleep. We know at least that sleep helps our memory. Almost every stages and features of sleep are involved memory consolidation, including non-rapid eye movement slow wave sleep (NREM SWS), NREM spindles, REM theta rhythm and sleep architecture continuity. Disruption of these stages and features are found in all neurological disorders afflicting memory (Angelman, autism spectrum, alcoholism, Alzheimer's, fragile X, Huntington's, Parkinson's, Rett etc…). The mechanisms underpinning these memory deficits are poorly understood and the role of sleep at the synapse is still highly debated. Synpases are the central physiological structures underpinning memory and cognition, but how each sleep stages and features remodels synapses remains unclear. NREM SWS and total sleep have been implicated in general synaptic downscaling, but NREM and spindles have also been involved in synaptic strengthening; similarly REM has been associated to both synapse pruning and maintenance. One major obstacle to such study has been that sleep stages and features are all interconnected and integrated. The disruption of one often impacts the others making the association between a stage/feature and a specific synaptic function challenging. Using precise optogenetic control of neuronal circuits, we have overcome this obstacle. Sleep continuity and memory consolidation can be disrupted without changing overall sleep architecture and quantity by introducing micro-arousals (<2sec) every 60 sec using hypocretin neuron stimulation (Aim 1). NREM sleep spindles and memory consolidation can be elicited by stimulating reticular thalamus neurons without disturbing sleep (Aim 2). Theta rhythms and memory consolidation can be disrupted by silencing medial septum GABA neurons during REM bouts only without affecting sleep architecture integrity (Aim 3). We will manipulate these three sleep features after a cortical motor learning task which rapidly induces synapse formation in the motor cortex. Remodeling of these newly formed synapses and their neighbors will be followed using state-of-the-art in vivo (two-photon) and ex vivo (array tomography) synapse microscopy. While the former longitudinal analysis will uncover the spine dynamics leading to memory encoding consolidation, the latter global synapse analysis will reveal how synapse classes (inhibitory, excitatory), synapse populations (depending on layers) and their subsynaptic molecular components are remodeled by sleep continuity (Aim 1), spindles (Aim 2) and REM specifically (Aim 3). The specific use of optogenetics to manipulate different sleep stages as synaptic dynamics are studied is unprecedented and will shed important light on how sleep continuity, NREM spindles, and REM can each influence cortical synaptic plasticity underpinning memory consolidation after motor learning. These discoveries are crucial for future strategies to recover and treat memory and cognitive deficits in neurodevelopmental and neurodegenerative disorders.