Self-sustained neural activity in the absence of ongoing external input is a fundamental feature of nervous system dynamics, yet the conditions under which it can emerge in biophysically grounded network models remain incompletely understood. We studied whether a recurrent network of Hodgkin-Huxley neurons with spike-timing-dependent plasticity and intrinsic stochasticity can maintain autonomous activity after brief transient stimulation. The simulated network comprised 200 neurons (160 excitatory, 40 inhibitory) with 80% connection probability, incorporating excitatory and inhibitory STDP, probabilistic vesicle release, probabilistic synapse formation, receptor variability, and voltage-dependent inhibition. After a brief 200 ms initialization stimulus to 30 excitatory neurons, the network received no further external input. In one 1800 s simulation and two additional 500 s simulations, the network maintained sparse, irregular activity without ongoing drive. In the 1800 s run, 67% of neurons exhibited mean firing rates below 1 Hz, the population mean firing rate was 1.13 +/- 1.34 Hz, participation increased across longer observation windows, and population-mean Fano factors remained near 1-2, consistent with irregular spike timing. Raster activity also showed spontaneous qualitative reorganizations in collective firing patterns over time. These findings suggest that recurrent Hodgkin-Huxley networks with plastic and stochastic synapses can sustain long-duration autonomous activity in a sparse firing regime after brief initialization.

翻译：在缺乏持续外部输入的情况下，神经系统的自维持活动是其动力学的基本特征，但生物物理网络模型中出现这一活动的条件尚未完全明确。我们研究了具有脉冲时序依赖可塑性和内在随机性的霍奇金-赫胥黎神经元递归网络，是否能在短暂瞬态刺激后维持自主活动。模拟网络包含200个神经元（160个兴奋性、40个抑制性），连接概率为80%，并整合了兴奋性与抑制性STDP、概率性囊泡释放、概率性突触形成、受体变异性以及电压依赖性抑制。在对30个兴奋性神经元进行200毫秒的初始化刺激后，网络不再接受任何外部输入。在1次1800秒和2次500秒的模拟中，网络在无持续输入条件下维持了稀疏且不规则的放电活动。在1800秒模拟中，67%的神经元平均放电频率低于1赫兹，群体平均放电频率为1.13±1.34赫兹，参与度随观测窗口延长而增加，群体平均Fano因子维持在1-2附近，与不规则脉冲时序一致。此外，光栅活动在时间维度上表现出集体放电模式的自发性质性重组。这些结果表明，具有可塑性和随机性突触的递归霍奇金-赫胥黎网络，在短暂初始化后能在稀疏放电状态下维持长时间的自主活动。