We consider a two-population network consisting of both inhibitory (I) interneurons and excitatory (E) pyramidal cells. This I–E neuronal network has adaptive dynamic I to E and E to I interpopulation synaptic strengths, governed by interpopulation spike-timing-dependent plasticity (STDP). In previous works without STDPs, fast sparsely synchronized rhythms, related to diverse cognitive functions, were found to appear in a range of noise intensity D for static synaptic strengths. Here, by varying D, we investigate the effect of interpopulation STDPs on fast sparsely synchronized rhythms that emerge in both the I- and the E-populations. Depending on values of D, long-term potentiation (LTP) and long-term depression (LTD) for population-averaged values of saturated interpopulation synaptic strengths are found to occur. Then, the degree of fast sparse synchronization varies due to effects of LTP and LTD. In a broad region of intermediate D, the degree of good synchronization (with higher synchronization degree) becomes decreased, while in a region of large D, the degree of bad synchronization (with lower synchronization degree) gets increased. Consequently, in each I- or E-population, the synchronization degree becomes nearly the same in a wide range of D (including both the intermediate and the large D regions). This kind of “equalization effect” is found to occur via cooperative interplay between the average occupation and pacing degrees of spikes (i.e., the average fraction of firing neurons and the average degree of phase coherence between spikes in each synchronized stripe of spikes in the raster plot of spikes) in fast sparsely synchronized rhythms. Finally, emergences of LTP and LTD of interpopulation synaptic strengths (leading to occurrence of equalization effect) are intensively investigated via a microscopic method based on the distributions of time delays between the pre- and the post-synaptic spike times.

中文翻译：

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群体间尖峰时间依赖性可塑性对具有抑制性和兴奋性群体的神经元网络中同步节律的影响。

我们考虑由抑制性 (I) 中间神经元和兴奋性 (E) 锥体细胞组成的双种群网络。这个 I-E 神经元网络具有自适应动态 I 到 E 和 E 到 I 种群间突触强度，由种群间尖峰时间依赖性可塑性 (STDP) 控制。在以前没有 STDP 的工作中，发现与不同认知功能相关的快速稀疏同步节奏出现在静态突触强度的噪声强度D范围内。在这里，通过改变D，我们研究了种群间 STDP 对出现在 I 和 E 种群中的快速稀疏同步节律的影响。取决于D 的值, 发现发生了饱和群体间突触强度的群体平均值的长期增强 (LTP) 和长期抑制 (LTD)。然后，快速稀疏同步的程度因 LTP 和 LTD 的影响而变化。在较大的中间D区域内，良好同步程度（同步度较高）变小，而在较大D区域内，不良同步度（同步度较低）增加。因此，在每个 I 或 E 种群中，同步度在很宽的D范围内变得几乎相同（包括中间和大D地区）。发现这种“均衡效应”是通过尖峰的平均占用度和起搏度（即，发射神经元的平均分数和光栅中每个同步尖峰条中尖峰之间的平均相位相干度）之间的协同相互作用而发生的。尖峰图）以快速稀疏同步的节奏。最后，通过基于突触前和突触后尖峰时间之间的时间延迟分布的微观方法，对群体间突触强度的 LTP 和 LTD 的出现（导致均衡效应的发生）进行了深入研究。