A synaptic organizing principle for cortical neuronal groups
A synaptic organizing principle for cortical neuronal groups
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DOI：
10.1073/pnas.1016051108
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发表时间：
2011-03-29
影响因子：
11.1
通讯作者：
Markram, Henry
中科院分区：
文献类型：
--
作者：
Perin, Rodrigo;Berger, Thomas K.;Markram, Henry
神经元电路通常被认为是一张空白的石板，可以由经验动态而任意地塑造。然而，当我们研究新皮质锥体神经元组的突触连接性时，我们发现连接性和突触重量都出人意料地可预测。突触重量与一组神经元中的连接数量密切相关，在一组神经元之间仅形成20%的可能连接后，突触权重就会饱和。当我们检查神经元之间连接的网络拓扑时，我们发现神经元聚集成小世界网络，这些网络不是无标度的，间隔不到2度。我们发现了一个简单的聚类规则，其中连通性与公共邻居的数量成正比，这解释了这些小世界网络，并准确地预测了任何两个神经元之间的连接概率。这个锥体神经元网络聚集成多个组，每个组几十个神经元。组成每一组神经元的分布令人惊讶，通常相距超过100微米，允许多组神经元在同一空间交错排列。总而言之，我们发现了一种突触组织原理，它以动物中常见的方式对神经元进行分组，因此不受个体经验的影响。我们推测，这些基本神经元组被规定为类似乐高积木的感知积木，获得的记忆更多地依赖于将这些基本组件组合成更高阶的结构。
Neuronal circuitry is often considered a clean slate that can be dynamically and arbitrarily molded by experience. However, when we investigated synaptic connectivity in groups of pyramidal neurons in the neocortex, we found that both connectivity and synaptic weights were surprisingly predictable. Synaptic weights follow very closely the number of connections in a group of neurons, saturating after only 20% of possible connections are formed between neurons in a group. When we examined the network topology of connectivity between neurons, we found that the neurons cluster into small world networks that are not scale-free, with less than 2 degrees of separation. We found a simple clustering rule where connectivity is directly proportional to the number of common neighbors, which accounts for these small world networks and accurately predicts the connection probability between any two neurons. This pyramidal neuron network clusters into multiple groups of a few dozen neurons each. The neurons composing each group are surprisingly distributed, typically more than 100 mu m apart, allowing for multiple groups to be interlaced in the same space. In summary, we discovered a synaptic organizing principle that groups neurons in a manner that is common across animals and hence, independent of individual experiences. We speculate that these elementary neuronal groups are prescribed Lego-like building blocks of perception and that acquired memory relies more on combining these elementary assemblies into higher-order constructs.