Mammalian cortical networks are active before synaptogenesis begins in earnest, before neuronal migration is complete, and well before an animal opens its eyes and begins to actively explore its surroundings. This early activity undergoes several transformations during development. The most important of these is a transition from episodic synchronous network events, which are necessary for patterning the neocortex into functionally related modules, to desynchronized activity that is computationally more powerful and efficient. Network desynchronization is perhaps the most dramatic and abrupt developmental event in an otherwise slow and gradual process of brain maturation. In this Review, we summarize what is known about the phenomenology of developmental synchronous activity in the rodent neocortex and speculate on the mechanisms that drive its eventual desynchronization. We argue that desynchronization of network activity is a fundamental step through which the cortex transitions from passive, bottom–up detection of sensory stimuli to active sensory processing with top–down modulation.

哺乳动物的皮层网络在突触发生真正开始之前，在神经元迁移完成之前，以及在动物睁开眼睛并开始积极探索周围环境之前就已经活跃了。这个早期活动在开发过程中经历了几次转变。其中最重要的是从情景同步网络事件（将新皮层模式化为功能相关模块所必需的）过渡到计算上更强大和高效的非同步活动。网络不同步可能是大脑成熟缓慢而渐进的过程中最戏剧性和最突然的发育事件。在这篇综述中，我们总结了关于啮齿动物新皮层发育同步活动的现象学的已知情况，并推测了驱动其最终不同步的机制。我们认为，网络活动的不同步是皮层从被动的、自下而上的感官刺激检测过渡到自上而下调制的主动感觉处理的基本步骤。