REM mechanisms in neocortical development

描述（由申请人提供）：眼优势可塑性是体内由双眼视觉变化触发的突触可塑性的典型形式。它为了解早期生命中皮层回路如何发展和重塑提供了重要的见解。我们已经证明，眼部优势可塑性通过类似于介导长期突触增强（LTP）的细胞机制得到巩固。我们的目标是更全面地识别这些机制以及它们发生的大脑状态。为了实现这一目标，我们将使用我们既定的方法来引发眼部优势可塑性，并结合行为状态监测、皮质内酶失活、内在皮质信号的光学成像、体内急性单神经元电生理学、自由行为动物中单神经元的慢性四极记录以及皮质蛋白的蛋白质印迹测量。这些技术结合在一个简单的实验设计中，使我们能够确定不同的大脑状态和细胞内信号通路如何促进皮质电路的持久修改。更具体地说，我们将测试以下假设：a) 快速眼动 (REM) 睡眠对于巩固眼部优势可塑性是必要的 b) 这是由 REM 睡眠中激活的蛋白激酶（Ca2/钙调蛋白依赖性蛋白激酶 [CaMKII] 和细胞外调节激酶 [ERK]）介导的。我们提出以下具体目标： 1. 确定快速眼动睡眠在巩固眼部优势可塑性中的作用。在这个目标中，我们将研究不同数量的快速眼动睡眠对两种不同类型的皮质可塑性的影响 需要加强视觉回路。这将通过定量测量和操纵自由行为动物的警戒状态和初级视觉皮层的双眼视觉输入来实现。接下来是体内皮质可塑性的三个独立且客观的测量（急性和慢性单神经元电生理学和内在皮质信号的光学成像）。 2.确定CaMKII和ERK在巩固眼部优势可塑性中的作用。在这个目标中，我们将研究 CaMKII 和 ERK 信号在强化睡眠期间发生的皮质回路中的作用。这将通过以下方式实现：a) 测量在不同量的视觉体验和快速眼动睡眠后处死的动物的初级视觉皮层中总的和磷酸化的 CaMKII 和 ERK 蛋白 b) 确定皮质内泛 CaMK、选择性 CaMKII 和 ERK 抑制对眼优势可塑性巩固的影响 c) 然后使用拟态和闭塞实验来确定 REM 睡眠的影响是否由 CaMK、CaMKII 或 ERK 激酶活性介导。我们的研究结果将为经验和内源性大脑活动如何指导皮层回路的发育和可塑性提供新的见解。他们还将提供有关正常和异常睡眠如何影响哺乳动物大脑发育的新信息。 公共健康相关性：本提案中的研究将为快速眼动 (REM) 睡眠如何促进大脑皮层的关键发育过程提供重要的新见解。这将提高我们对正常和病理性大脑发育以及早期睡眠功能的理解。

DESCRIPTION (provided by applicant): Ocular dominance plasticity is a canonical form of synaptic plasticity in vivo triggered by changes in binocular vision. It has provided crucial insights into how cortical circuits develop and remodel in early life. We have shown that ocular dominance plasticity is consolidated via cellular mechanisms similar to those mediating long-term synaptic potentiation (LTP). Our goal is to more completely identify these mechanisms and the brain states in which they occur. To achieve this goal we will use our established methods of eliciting ocular dominance plasticity combined with behavioral state monitoring, inactivation of intracortical enzymes, optical imaging of intrinsic cortical signals, acute single-neuron electrophysiology in vivo, chronic tetrode recording of single-neurons in freely-behaving animals, and Western blot measurements of cortical proteins. These techniques are combined in a simple experimental design that allows us to determine how different brain states and intracellular signaling pathways promote long-lasting modifications of cortical circuitry. More specifically, we will test the following hypotheses a) rapid-eye-movement (REM) sleep is necessary for the consolidation of ocular dominance plasticity b) this is mediated by protein kinases (Ca2+/calmodulin- dependent protein kinase [CaMKII] and extracellular regulated kinase [ERK]) activated in REM sleep. We propose the following Specific Aims: 1. Determine the role of REM sleep in the consolidation of ocular dominance plasticity. In this Aim, we will examine the effects of different amounts of REM sleep on two different types of cortical plasticity that require strengthening of visual circuits. This will be accomplished by quantitatively measuring and manipulating vigilance states and binocular visual input to primary visual cortex in the freely-behaving animal. This is followed by three independent and objective measures of cortical plasticity in vivo (acute and chronic single-neuron electrophysiology and optical imaging of intrinsic cortical signals). 2. Determine the role of CaMKII and ERK in the consolidation of ocular dominance plasticity. In this Aim, we will examine the role of CaMKII and ERK signaling in the strengthening of cortical circuits that occurs during sleep. This will be achieved by a) measuring total and phosphorylated CaMKII and ERK proteins in the primary visual cortices of animals that are sacrificed after different amounts of visual experience and rapid- eye-movement sleep b) determining the effects of intracortical pan-CaMK, selective CaMKII and ERK inhibition on the consolidation of ocular dominance plasticity c) mimicry and occlusion experiments are then used to determine if the effects of REM sleep are mediated by CaMK, CaMKII or ERK kinase activity. The results of our investigations will provide new insights into how experience and endogenous brain activity guide cortical circuit development and plasticity. They will also provide new information about how normal and abnormal sleep impacts mammalian brain development. PUBLIC HEALTH RELEVANCE: The research in this proposal will provide important new insights into how rapid-eye-movement (REM) sleep promotes critical developmental processes in the cerebral cortex. This will improve our understanding of normal and pathological brain development and the function of sleep in early life.