Functional role of symmetric and asymmetric STDP rules in sequence learning in the brain

我们研究了对称和非对称STDP学习规则在内嗅皮层和海马的顺序学习中的作用。说明了对称STDP学习规则适用于在背景噪声条件下建立代表位置序列的环路连接序列。而非对称STDP学习规则则适用于突触竞争选择空间信息（如气味等有价值的非空间信息），并引起海马CA3网络神经元活动的定向传播。这些结果表明，为了揭示由海马和内嗅皮层组成的整个系统的序列学习机制，考虑哪些STDP学习规则适合局部网络结构是很重要的。

We investigated roles of symmetric and asymmetric STDP learning rules in sequence learning in the entorhinal cortex and the hippocampus. It was elucidated that the symmetric STDP learning rule was suitable for establishing a sequence of loop connections, which represented a sequence of places, amid background noise. In contrast, the asymmetric STDP learning rule was suitable for synaptic competition to select spatial information accompanied by valuable non-spatial information such as odor and to cause directional propagation of neuronal activity in the hippocampal CA3 network. These results suggest that it is important to consider what STDP learning rules are suitable for local network structures in order to unveil mechanisms of the sequence learning in the whole system consisting of the hippocampus and the entorhinal cortex.