Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Neurosci. 2010 Aug 18;30(33):11086-95. doi: 10.1523/JNEUROSCI.1661-10.2010.
The impact of activity on neuronal circuitry is complex, involving both functional and structural changes whose interaction is largely unknown. We have used optical imaging of mouse visual cortex responses and two-photon imaging of superficial layer spines on layer 5 neurons to monitor network function and synaptic structural dynamics in the mouse visual cortex in vivo. Total lack of vision due to dark-rearing from birth dampens visual responses and shifts spine dynamics and morphologies toward an immature state. The effects of vision after dark rearing are strongly dependent on the timing of exposure: over a period of days, functional and structural changes are temporally related such that light stabilizes spines while increasing visually driven activity. The effects of long-term light exposure can be partially mimicked by experimentally enhancing inhibitory signaling in the darkness. Brief light exposure, however, results in a rapid, transient, NMDA-dependent increase of cortical responses, accompanied by increased dynamics of dendritic spines. These findings indicate that visual experience induces rapid reorganization of cortical circuitry followed by a period of stabilization, and demonstrate a close relationship between dynamic changes at single synapses and cortical network function.
活动对神经元回路的影响很复杂，涉及功能和结构变化，其相互作用在很大程度上尚不清楚。我们使用光学成像技术来监测小鼠视觉皮层的反应，并使用双光子显微镜对浅层 5 层神经元的棘突进行成像，从而在体内监测小鼠视觉皮层的网络功能和突触结构动态。由于出生后就处于黑暗环境中而导致的完全失明会抑制视觉反应，并使棘突动力学和形态向不成熟状态转变。黑暗饲养后再接受视觉刺激的效果强烈依赖于暴露的时间：在几天的时间内，功能和结构变化是时间相关的，因此光照可以稳定棘突，同时增加视觉驱动的活动。在黑暗中实验性地增强抑制性信号可以部分模拟长期光照的效果。然而，短暂的光照会导致皮质反应的快速、短暂、NMDA 依赖性增加，并伴有树突棘突动力学的增加。这些发现表明，视觉体验会引起皮质回路的快速重组，然后是一段稳定期，并证明了单个突触的动态变化与皮质网络功能之间存在密切关系。
