Highly Heterogeneous Excitatory Connections Require Less Amount of Noise to Sustain Firing Activities in Cortical Networks
Highly Heterogeneous Excitatory Connections Require Less Amount of Noise to Sustain Firing Activities in Cortical Networks
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DOI：
10.3389/fncom.2018.00104
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发表时间：
2018-12-21
影响因子：
3.2
通讯作者：
Tokuda, Isao T.
中科院分区：
文献类型：
--
作者：
Kada, Hisashi;Teramae, Jun-nosuke;Tokuda, Isao T.
体内和体外的皮质网络都能维持极低频率的非同步不规则放电。为了在神经网络模型中实现这种自我持续的活动，兴奋性和抑制性活动之间的平衡是关键之一。此外，最近的理论研究表明，皮层网络中常见的另一个特征，即稀疏但强的连接和密集的弱连接，在其中起着至关重要的作用。然而，以往的研究并没有充分考虑这种异质突触连接网络与内在噪声之间的合作动力学。噪声刺激代表了神经元活动的固有性质，例如突触前放电的可变性，对于维持皮层网络中的不规则放电也应该具有重要意义。在这里，我们在数值上证明了高度非均匀分布（通常是对数正态型）的兴奋性到兴奋性连接减少了维持网络发射活动所需的噪声量。从噪声消耗能量的意义上说，接受较少噪声刺激的异构网络可以实现皮层的高效动态。双模态分布突触的噪声驱动网络进一步表明，许多弱突触和一些非常强的突触是突触异质性的关键特征，支持网络发射活动。
Cortical networks both in vivo and in vitro sustain asynchronous irregular firings with extremely low frequency. To realize such self-sustained activity in neural network models, balance between excitatory and inhibitory activities is known to be one of the keys. In addition, recent theoretical studies have revealed that another feature commonly observed in cortical networks, i.e., sparse but strong connections and dense weak connections, plays an essential role. The previous studies, however, have not thoroughly considered the cooperative dynamics between a network of such heterogeneous synaptic connections and intrinsic noise. The noise stimuli, representing inherent nature of the neuronal activities, e.g., variability of presynaptic discharges, should be also of significant importance for sustaining the irregular firings in cortical networks. Here, we numerically demonstrate that highly heterogeneous distribution, typically a lognormal type, of excitatory-to-excitatory connections, reduces the amount of noise required to sustain the network firing activities. In the sense that noise consumes an energy resource, the heterogeneous network receiving less amount of noise stimuli is considered to realize an efficient dynamics in cortex. A noise-driven network of bi-modally distributed synapses further shows that many weak and a few very strong synapses are the key feature of the synaptic heterogeneity, supporting the network firing activity.