Autoassociative memory retrieval and spontaneous activity bumps in small-world networks of integrate-and-fire neurons
Autoassociative memory retrieval and spontaneous activity bumps in small-world networks of integrate-and-fire neurons
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DOI：
10.1016/j.jphysparis.2007.01.004
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发表时间：
2006-10-01
影响因子：
--
通讯作者：
Treves, Alessandro
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文献类型：
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作者：
Anishchenko, Anastasia;Treves, Alessandro
突触连接的度量结构显然是塑造神经网络特性的重要因素，特别是检索记忆的能力，神经网络被赋予了通过吸引子动力学操作的自联想网络。定性地说，大脑中的一些真实网络可以被描述为“小世界”，从这个意义上说，它们的连接结构介于有序几何排列和几何无关的随机网格的极端之间。小世界可以用它们的平均路径长度和聚集系数来更精确地定义；但这样精确的描述对于更好地理解连接类型如何影响记忆提取有用吗？我们模拟了一个由整合与开火单元组成的自联想记忆网络，它位于一个环上，网络连接在有序和随机之间参数变化。我们发现，当连通性接近随机时，网络检索先前存储的记忆模式，并且当连通性接近于有序时，网络显示有序网的特征行为(局部的活动“凸起”)。最近的分析工作表明，这两种行为可以共存于一个简单的阈值-线性单元网络中，从而导致局部提取状态。然而，我们发现，对于我们的整合与开火单位，它们往往是相互排斥的行为。此外，这两个参数之间的转换发生在连接性参数值之间，而这些参数值不仅仅与小世界的概念有关。(C)2007爱思唯尔有限公司。保留所有权利。
The metric structure of synaptic connections is obviously an important factor in shaping the properties of neural networks, in particular the capacity to retrieve memories, with which are endowed autoassociative nets operating via attractor dynamics. Qualitatively, some real networks in the brain could be characterized as 'small worlds', in the sense that the structure of their connections is intermediate between the extremes of an orderly geometric arrangement and of a geometry-independent random mesh. Small worlds can be defined more precisely in terms of their mean path length and clustering coefficient; but is such a precise description useful for a better understanding of how the type of connectivity affects memory retrieval?We have simulated an autoassociative memory network of integrate-and-fire units, positioned on a ring, with the network connectivity varied parametrically between ordered and random. We find that the network retrieves previously stored memory patterns when the connectivity is close to random, and displays the characteristic behavior of ordered nets (localized 'bumps' of activity) when the connectivity is close to ordered. Recent analytical work shows that these two behaviors can coexist in a network of simple threshold -linear units, leading to localized retrieval states. We find that they tend to be mutually exclusive behaviors, however, with our integrate-and-fire units. Moreover, the transition between the two occurs for values of the connectivity parameter which are not simply related to the notion of small worlds. (c) 2007 Elsevier Ltd. All rights reserved.