Statistical connectivity provides a sufficient foundation for specific functional connectivity in neocortical neural microcircuits
Statistical connectivity provides a sufficient foundation for specific functional connectivity in neocortical neural microcircuits
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DOI：
10.1073/pnas.1202128109
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发表时间：
2012-10-16
影响因子：
11.1
通讯作者：
Markram, Henry
中科院分区：
文献类型：
--
作者：
Hill, Sean L.;Wang, Yun;Markram, Henry
众所周知，突触的形成涉及高度选择性的化学特异性机制，但神经元乔木在突触形成之前是如何定位的仍不清楚。通过对298个不同类型的新皮层细胞（巢篮、小篮、大篮、沥青、锥体和Martinotti细胞）的三维重建，我们构建了一个皮层微电路的结构模型，其中不同类型的细胞被独立和随机放置。我们比较了模型中由轴突和树突树突偶然重叠引起的物理重合位置（统计结构连通性）与从皮层切片制备中重建的90个突触连接中假定的功能突触位置（功能性突触连通性）。总体而言，我们发现统计连通性预测9种皮质连接类型的突触位置分布平均为74 +/- 2.7%（平均+/- SEM）。这一发现表明，化学特异性的吸引和排斥机制通常不会导致成对特异性的连接。然而，在某些情况下，预测的分布并不精确匹配，这表明在某些类型的连接中可能会发生化学特异性的转向和对准。这一发现表明，轴突和树突的随机排列为局部神经微回路中出现的特定功能连接提供了充分的基础。
It is well-established that synapse formation involves highly selective chemospecific mechanisms, but how neuron arbors are positioned before synapse formation remains unclear. Using 3D reconstructions of 298 neocortical cells of different types (including nest basket, small basket, large basket, bitufted, pyramidal, and Martinotti cells), we constructed a structural model of a cortical microcircuit, in which cells of different types were independently and randomly placed. We compared the positions of physical appositions resulting from the incidental overlap of axonal and dendritic arbors in the model (statistical structural connectivity) with the positions of putative functional synapses (functional synaptic connectivity) in 90 synaptic connections reconstructed from cortical slice preparations. Overall, we found that statistical connectivity predicted an average of 74 +/- 2.7% (mean +/- SEM) synapse location distributions for nine types of cortical connections. This finding suggests that chemospecific attractive and repulsive mechanisms generally do not result in pairwise-specific connectivity. In some cases, however, the predicted distributions do not match precisely, indicating that chemospecific steering and aligning of the arbors may occur for some types of connections. This finding suggests that random alignment of axonal and dendritic arbors provides a sufficient foundation for specific functional connectivity to emerge in local neural microcircuits.