PDF(Pubmed)
Abstract：
Synaptic inputs to cortical neurons are highly structured in adult sensory systems, such that neighboring synapses along dendrites are activated by similar stimuli. This organization of synaptic inputs, called synaptic clustering, is required for high-fidelity signal processing, and clustered synapses can already be observed before eye opening. However, how clustered inputs emerge during development is unknown. Here, we employed concurrent in vivo whole-cell patch-clamp and dendritic calcium imaging to map spontaneous synaptic inputs to dendrites of layer 2/3 neurons in the mouse primary visual cortex during the second postnatal week until eye opening. We found that the number of functional synapses and the frequency of transmission events increase several fold during this developmental period. At the beginning of the second postnatal week, synapses assemble specifically in confined dendritic segments, whereas other segments are devoid of synapses. By the end of the second postnatal week, just before eye opening, dendrites are almost entirely covered by domains of co-active synapses. Finally, co-activity with their neighbor synapses correlates with synaptic stabilization and potentiation. Thus, clustered synapses form in distinct functional domains presumably to equip dendrites with computational modules for high-capacity sensory processing when the eyes open.
摘要：
对皮质神经元的突触输入在成人感觉系统中是高度结构化的，使得沿着树突的相邻突触被类似的刺激激活。这种突触输入的组织，称为突触聚类，是高保真信号处理所必需的，在睁眼之前已经可以观察到聚集的突触。然而,在开发过程中如何出现集群输入是未知的。这里,在出生后第2周,我们同时进行体内全细胞膜片钳和树突状钙成像,将自发突触输入映射到小鼠初级视皮层2/3层神经元的树突,直至睁眼.我们发现，在这个发育期，功能性突触的数量和传递事件的频率增加了几倍。在产后第二个星期开始时，突触在狭窄的树突节段中特别组装，而其他片段缺乏突触。产后第二周结束时，就在睁开眼睛之前，树突几乎完全被协同突触的结构域覆盖。最后,与相邻突触的协同作用与突触的稳定和增强有关。因此，聚集的突触形成在不同的功能域中，大概是为树突配备了计算模块，以在睁开眼睛时进行高容量的感觉处理。
