Specific synapses develop preferentially among sister excitatory neurons in the neocortex.
Specific synapses develop preferentially among sister excitatory neurons in the neocortex.
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DOI：
10.1038/nature07722
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发表时间：
2009-03-26
期刊：
影响因子：
64.8
通讯作者：
Shi, Song-Hai
中科院分区：
文献类型：
--
作者：
Yu, Yong-Chun;Bultje, Ronald S.;Wang, Xiaoqun;Shi, Song-Hai
哺乳动物新皮层中的神经元被组织成功能柱。在一个柱中，形成了高度特异性的突触连接，以确保从丘脑到白质的神经元群共享相似的生理特性。最近的研究表明，新皮层的突触连接是稀疏的和高度特异性的，甚至允许相邻的神经元独立地传递信息。这个精细的微电路是如何在单个神经元的水平上构建一个功能柱状结构的，这在很大程度上仍然是一个谜。在这里，我们研究了在发育中的新皮层中由同一母细胞产生的兴奋性神经元的径向克隆是否作为形成这种高度特异性微电路的底物。我们在小鼠新皮层神经发生高峰期前后，通过在子宫内室内注射表达egfp的逆转录病毒，标记了小鼠新皮层兴奋性神经元的个体发生径向克隆。通过多电极全细胞记录来探测这些egfp标记的姐妹兴奋性神经元在出生后的放射状克隆和邻近的非兄弟姐妹之间的突触形成。我们发现放射状排列的姐妹兴奋性神经元倾向于相互之间发展单向化学突触，而不是与邻近的非兄弟姐妹。此外，这些突触连接表现出与在成熟的新皮层中观察到的相同的层间方向偏好。这些结果表明，在发育中的新皮层中，特定的微电路在兴奋性神经元的个体发生径向克隆中优先发育，并有助于成熟的新皮层中出现功能性柱状微结构。
Neurons in the mammalian neocortex are organized into functional columns. Within a column, highly specific synaptic connections are formed to ensure that similar physiological properties are shared by neuron ensembles spanning from the pia to the white matter. Recent studies suggest that synaptic connectivity in the neocortex is sparse and highly specific to allow even adjacent neurons to convey information independently. How this fine-scale microcircuit is constructed to create a functional columnar architecture at the level of individual neurons largely remains a mystery. Here we investigate whether radial clones of excitatory neurons arising from the same mother cell in the developing neocortex serve as a substrate for the formation of this highly specific microcircuit. We labelled ontogenetic radial clones of excitatory neurons in the mouse neocortex by in utero intraventricular injection of EGFP-expressing retroviruses around the onset of the peak phase of neocortical neurogenesis. Multiple-electrode whole-cell recordings were performed to probe synapse formation among these EGFP-labelled sister excitatory neurons in radial clones and the adjacent non-siblings during postnatal stages. We found that radially aligned sister excitatory neurons have a propensity for developing unidirectional chemical synapses with each other rather than with neighbouring non-siblings. Moreover, these synaptic connections display the same interlaminar directional preference as those observed in the mature neocortex. These results suggest that specific microcircuits develop preferentially within ontogenetic radial clones of excitatory neurons in the developing neocortex and contribute to the emergence of functional columnar microarchitectures in the mature neocortex.
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