Computational Neurobiology Laboratory and Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Proc Natl Acad Sci U S A. 2013 May 7;110(19):7886-91. doi: 10.1073/pnas.1305219110. Epub 2013 Apr 22.
Cortical spike trains are highly irregular both during ongoing, spontaneous activity and when driven at high firing rates. There is uncertainty about the source of this irregularity, ranging from intrinsic noise sources in neurons to collective effects in large-scale cortical networks. Cortical interneurons display highly irregular spike times (coefficient of variation of the interspike intervals >1) in response to dc-current injection in vitro. This is in marked contrast to cortical pyramidal cells, which spike highly irregularly in vivo, but regularly in vitro. We show with in vitro recordings and computational models that this is due to the fast activation kinetics of interneuronal K(+) currents. This explanation holds over a wide parameter range and with Gaussian white, power-law, and Ornstein-Uhlenbeck noise. The intrinsically irregular spiking of interneurons could contribute to the irregularity of the cortical network.
皮质尖峰序列在持续的自发性活动和高频率驱动时都具有高度不规则性。这种不规则性的来源存在不确定性，范围从神经元中的固有噪声源到大规模皮质网络中的集体效应。在体外，皮质中间神经元在直流电流注入时表现出高度不规则的尖峰时间（尖峰间隔的变异系数 >1）。这与皮质锥体神经元形成鲜明对比，后者在体内高度不规则地尖峰，但在体外规则地尖峰。我们通过体外记录和计算模型表明，这是由于中间神经元 K+电流的快速激活动力学。这种解释适用于广泛的参数范围和高斯白噪声、幂律噪声和 Ornstein-Uhlenbeck 噪声。中间神经元的固有不规则尖峰可能导致皮质网络的不规则性。
