Center for Theoretical Neuroscience and Department of Neuroscience, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA; RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Department of Computational Intelligence and Systems Science, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
Neuron. 2013 Oct 2;80(1):51-63. doi: 10.1016/j.neuron.2013.07.022.
What causes critical periods (CPs) to open? For the best-studied case, ocular dominance plasticity in primary visual cortex in response to monocular deprivation (MD), the maturation of inhibition is necessary and sufficient. How does inhibition open the CP? We present a theory: the transition from pre-CP to CP plasticity arises because inhibition preferentially suppresses responses to spontaneous relative to visually driven input activity, switching learning cues from internal to external sources. This differs from previous proposals in (1) arguing that the CP can open without changes in plasticity mechanisms when activity patterns become more sensitive to sensory experience through circuit development, and (2) explaining not simply a transition from no plasticity to plasticity, but a change in outcome of MD-induced plasticity from pre-CP to CP. More broadly, hierarchical organization of sensory-motor pathways may develop through a cascade of CPs induced as circuit maturation progresses from "lower" to "higher" cortical areas.
是什么导致了关键期（CPs）的开启？对于研究最充分的案例，即初级视觉皮层中对单眼剥夺（MD）的眼优势可塑性，抑制作用的成熟是必要且充分的。那么抑制作用是如何开启 CP 的呢？我们提出了一个理论：从 CP 前到 CP 可塑性的转变是因为抑制作用优先抑制自发的相对视觉驱动输入活动的反应，从而将学习线索从内部来源切换到外部来源。这与之前的观点不同，之前的观点认为，当通过电路发展使活动模式对感官体验变得更加敏感时，CP 可以在不改变可塑性机制的情况下开启，并且（2）解释的不仅仅是从无可塑性到可塑性的转变，而是 MD 诱导的可塑性从 CP 前到 CP 的结果的变化。更广泛地说，感觉运动通路的分层组织可能是通过随着电路成熟从“较低”到“较高”皮层区域的进展而引发的一系列 CP 而发展起来的。
