Shimono Masanori, Beggs John M
Indiana University Bloomington, Bloomington, IN 47405, USA.
Cereb Cortex. 2015 Oct;25(10):3743-57. doi: 10.1093/cercor/bhu252. Epub 2014 Oct 21.
Although relationships between networks of different scales have been observed in macroscopic brain studies, relationships between structures of different scales in networks of neurons are unknown. To address this, we recorded from up to 500 neurons simultaneously from slice cultures of rodent somatosensory cortex. We then measured directed effective networks with transfer entropy, previously validated in simulated cortical networks. These effective networks enabled us to evaluate distinctive nonrandom structures of connectivity at 2 different scales. We have 4 main findings. First, at the scale of 3-6 neurons (clusters), we found that high numbers of connections occurred significantly more often than expected by chance. Second, the distribution of the number of connections per neuron (degree distribution) had a long tail, indicating that the network contained distinctively high-degree neurons, or hubs. Third, at the scale of tens to hundreds of neurons, we typically found 2-3 significantly large communities. Finally, we demonstrated that communities were relatively more robust than clusters against shuffling of connections. We conclude the microconnectome of the cortex has specific organization at different scales, as revealed by differences in robustness. We suggest that this information will help us to understand how the microconnectome is robust against damage.
尽管在宏观脑研究中已观察到不同尺度网络之间的关系，但神经元网络中不同尺度结构之间的关系尚不清楚。为了解决这个问题，我们从啮齿动物体感皮层的切片培养物中同时记录了多达500个神经元的活动。然后，我们用转移熵测量了有向有效网络，转移熵先前已在模拟皮层网络中得到验证。这些有效网络使我们能够评估2种不同尺度下独特的非随机连接结构。我们有4个主要发现。第一，在3至6个神经元（簇）的尺度上，我们发现大量连接出现的频率显著高于随机预期。第二，每个神经元的连接数分布（度分布）有一个长尾，表明该网络包含明显的高连接度神经元或枢纽。第三，在数十到数百个神经元的尺度上，我们通常发现2至3个明显大的群落。最后，我们证明群落相对于簇在连接重排方面具有更强的稳健性。我们得出结论，皮层的微连接组在不同尺度上具有特定的组织，这通过稳健性的差异得以揭示。我们认为这些信息将有助于我们理解微连接组如何抵抗损伤。
