Xu Kesheng, Zhang Xiyun, Wang Chaoqing, Liu Zonghua
Department of Physics, East China Normal University, Shanghai, 200062, China.
Sci Rep. 2014 Dec 19;4:7568. doi: 10.1038/srep07568.
Many experiments have evidenced the transition with different time scales from short-term memory (STM) to long-term memory (LTM) in mammalian brains, while its theoretical understanding is still under debate. To understand its underlying mechanism, it has recently been shown that it is possible to have a long-period rhythmic synchronous firing in a scale-free network, provided the existence of both the high-degree hubs and the loops formed by low-degree nodes. We here present a simplified memory network model to show that the self-sustained synchronous firing can be observed even without these two necessary conditions. This simplified network consists of two loops of coupled excitable neurons with different synaptic conductance and with one node being the sensory neuron to receive an external stimulus signal. This model can be further used to show how the diversity of firing patterns can be selectively formed by varying the signal frequency, duration of the stimulus and network topology, which corresponds to the patterns of STM and LTM with different time scales. A theoretical analysis is presented to explain the underlying mechanism of firing patterns.
许多实验已经证明，哺乳动物大脑中存在从短期记忆（STM）到长期记忆（LTM）的不同时间尺度的转变，但其理论理解仍在争论中。为了理解其潜在机制，最近有研究表明，在无标度网络中，只要存在高度枢纽和由低度节点形成的回路，就有可能产生长周期的节律性同步放电。我们在此提出一个简化的记忆网络模型，以表明即使没有这两个必要条件，也能观察到自持同步放电。这个简化网络由两个具有不同突触电导的耦合可兴奋神经元回路组成，其中一个节点是接收外部刺激信号的感觉神经元。该模型还可进一步用于展示如何通过改变信号频率、刺激持续时间和网络拓扑结构来选择性地形成放电模式的多样性，这与不同时间尺度的STM和LTM模式相对应。本文进行了理论分析以解释放电模式的潜在机制。
