University of Ottawa, Institute of Mental Health Research, Ottawa ON K1Z 7K4, Canada.
Department of Biomedical Engineering, Hamedan University of Technology, Hamedan 65169-13733, Iran.
Cereb Cortex. 2023 Oct 9;33(20):10477-10491. doi: 10.1093/cercor/bhad297.
Electroencephalography studies link sensory processing issues in schizophrenia to increased noise level-noise here is background spontaneous activity-as measured by the signal-to-noise ratio. The mechanism, however, of such increased noise is unknown. We investigate if this relates to changes in cortical excitation-inhibition balance, which has been observed to be atypical in schizophrenia, by combining electroencephalography and computational modeling. Our electroencephalography task results, for which the local field potentials can be used as a proxy, show lower signal-to-noise ratio due to higher noise in schizophrenia. Both electroencephalography rest and task states exhibit higher levels of excitation in the functional excitation-inhibition (as a proxy of excitation-inhibition balance). This suggests a relationship between increased noise and atypical excitation in schizophrenia, which was addressed by using computational modeling. A Leaky Integrate-and-Fire model was used to simulate the effects of varying degrees of noise on excitation-inhibition balance, local field potential, NMDA current, and . Results show a noise-related increase in the local field potential, excitation in excitation-inhibition balance, pyramidal NMDA current, and spike rate. Mutual information and mediation analysis were used to explore a cross-level relationship, showing that the cortical local field potential plays a key role in transferring the effect of noise to the cellular population level of NMDA.
脑电图研究将精神分裂症中的感觉处理问题与噪声水平增加联系起来——这里的噪声是指背景自发活动——这可以通过信噪比来衡量。然而，这种噪声增加的机制尚不清楚。我们通过结合脑电图和计算建模来研究这是否与皮质兴奋抑制平衡的变化有关，这种平衡在精神分裂症中被观察到是非典型的。我们的脑电图任务结果（局部场电位可以作为替代物）显示，由于精神分裂症中的噪声较高，信噪比较低。无论是在脑电图的静息状态还是任务状态下，功能性兴奋抑制（作为兴奋抑制平衡的替代物）的兴奋水平都较高。这表明在精神分裂症中，噪声增加与兴奋异常之间存在关系，这一点通过计算建模得到了证实。我们使用 Leaky Integrate-and-Fire 模型来模拟不同程度噪声对兴奋抑制平衡、局部场电位、NMDA 电流和尖峰发放率的影响。结果表明，局部场电位、兴奋抑制平衡、锥体 NMDA 电流和尖峰发放率都出现了与噪声相关的增加。互信息和中介分析用于探索跨层次关系，表明皮质局部场电位在将噪声的影响传递到 NMDA 细胞群体水平方面起着关键作用。
