Objective. Transcranial alternating current stimulation (tACS) can be used to non-invasively entrain neural activity and thereby cause changes in local neural oscillatory power. Despite its increased use in cognitive and clinical neuroscience, the fundamental mechanisms of tACS are still not fully understood. Approach. We developed a computational neuronal network model of two-compartment pyramidal neurons (PY) and inhibitory interneurons, which mimic the local cortical circuits. We modeled tACS with electric field strengths that are achievable in human applications. We then simulated intrinsic network activity and measured neural entrainment to investigate how tACS modulates ongoing endogenous oscillations. Main results. The intensity-specific effects of tACS are non-linear. At low intensities (<0.3 mV mm⁻¹), tACS desynchronizes neural firing relative to the endogenous oscillations. At higher intensities (>0.3 mV mm⁻¹), neurons are entrained to the exogenous electric field. We then further explore the stimulation parameter space and find that the entrainment of ongoing cortical oscillations also depends on stimulation frequency by following an Arnold tongue. Moreover, neuronal networks can amplify the tACS-induced entrainment via synaptic coupling and network effects. Our model shows that PY are directly entrained by the exogenous electric field and drive the inhibitory neurons. Significance. The results presented in this study provide a mechanistic framework for understanding the intensity- and frequency-specific effects of oscillating electric fields on neuronal networks. This is crucial for rational parameter selection for tACS in cognitive studies and clinical applications.

中文翻译：

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通过网络动力学解释经颅交流电刺激的强度和频率特异性效应

客观的。经颅交流电刺激（tACS）可用于无创地诱导神经活动，从而引起局部神经振荡功率的变化。尽管 tACS 在认知和临床神经科学中的应用越来越多，但其基本机制仍未完全了解。方法。我们开发了一个由两室锥体神经元（PY）和抑制性中间神经元组成的计算神经元网络模型，它模仿了局部皮质回路。我们使用人类应用中可实现的电场强度对 tACS 进行建模。然后，我们模拟内在网络活动并测量神经夹带，以研究 tACS 如何调节持续的内源振荡。主要成果。 tACS 的强度特异性效应是非线性的。在低强度（<0.3 mV mm ^-1）下，tACS 使神经放电相对于内源性振荡去同步。在较高强度（>0.3 mV mm ^-1）下，神经元被夹带到外源电场中。然后，我们进一步探索刺激参数空间，发现持续皮质振荡的夹带也取决于遵循阿诺德舌头的刺激频率。此外，神经元网络可以通过突触耦合和网络效应放大 tACS 诱导的夹带。我们的模型表明，PY 直接被外源电场夹带并驱动抑制性神经元。意义。这项研究中提出的结果为理解振荡电场对神经元网络的强度和频率特定影响提供了一个机制框架。这对于认知研究和临床应用中 tACS 的合理参数选择至关重要。