基于发放时间依赖可塑性的递归神经网络中网络结构的出现III:由自发活动驱动的部分连接神经元
Emergence of network structure due to spike-timing-dependent plasticity in recurrent neuronal networks III: Partially connected neurons driven by spontaneous activity.
作者信息
Gilson Matthieu, Burkitt Anthony N, Grayden David B, Thomas Doreen A, van Hemmen J Leo
机构信息
Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia.
出版信息
Biol Cybern. 2009 Dec;101(5-6):411-26. doi: 10.1007/s00422-009-0343-4. Epub 2009 Nov 24.
In contrast to a feed-forward architecture, the weight dynamics induced by spike-timing-dependent plasticity (STDP) in a recurrent neuronal network is not yet well understood. In this article, we extend a previous study of the impact of additive STDP in a recurrent network that is driven by spontaneous activity (no external stimulating inputs) from a fully connected network to one that is only partially connected. The asymptotic state of the network is analyzed, and it is found that the equilibrium and stability conditions for the firing rates are similar for both full and partial connectivity: STDP causes the firing rates to converge toward the same value and remain quasi-homogeneous. However, when STDP induces strong weight competition, the connectivity affects the weight dynamics in that the distribution of the weights disperses more quickly for lower density than for higher density. The asymptotic weight distribution strongly depends upon that at the beginning of the learning epoch; consequently, homogeneous connectivity alone is not sufficient to obtain homogeneous neuronal activity. In the absence of external inputs, STDP can nevertheless generate structure in the network through autocorrelation effects, for example, by introducing asymmetry in network topology.
与前馈架构不同,循环神经网络中由尖峰时间依赖可塑性(STDP)引起的权重动态尚未得到很好的理解。在本文中,我们扩展了先前的一项研究,该研究探讨了在由自发活动(无外部刺激输入)驱动的循环网络中,全连接网络的加法STDP的影响,扩展到了仅部分连接的网络。分析了网络的渐近状态,发现全连接和部分连接情况下, firing速率的平衡和稳定性条件相似:STDP使firing速率趋向于相同的值并保持准均匀。然而,当STDP引起强烈的权重竞争时,连接性会影响权重动态,因为对于较低密度,权重的分布比较高密度时更快地分散。渐近权重分布强烈依赖于学习阶段开始时的分布;因此,仅均匀连接不足以获得均匀的神经元活动。在没有外部输入的情况下,STDP仍然可以通过自相关效应在网络中产生结构,例如,通过在网络拓扑中引入不对称性。