REM mechanisms in neocortical development

描述（申请人提供）：眼优势可塑性是由双目视觉变化引发的体内突触可塑性的典型形式。它提供了关于大脑皮层回路如何在生命早期发育和重塑的重要见解。我们已经证明，眼优势可塑性是通过类似于长期突触增强（LTP）的细胞机制巩固的。我们的目标是更全面地确定这些机制以及它们发生时的大脑状态。为了实现这一目标，我们将使用我们已经建立的方法，结合行为状态监测、皮质内酶失活、皮质内在信号的光学成像、体内急性单神经元电生理、自由行为动物单神经元的慢性四极记录和皮质蛋白的Western blot测量，来激发眼优势可塑性。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层电路的持久修改。更具体地说，我们将测试以下假设：a)快速眼动（REM）睡眠对于巩固眼优势可塑性是必要的；b)这是由蛋白激酶介导的（Ca2+/钙调蛋白依赖性蛋白激酶[CaMKII]和细胞外调节激酶[ERK]）在REM睡眠中激活。我们提出以下具体目标：确定REM睡眠在眼优势可塑性巩固中的作用。在这篇文章中，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层可塑性的影响

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.