Identification of the current generator underlying cholinergically induced gamma frequency field potential oscillations in the hippocampal CA3 region
Identification of the current generator underlying cholinergically induced gamma frequency field potential oscillations in the hippocampal CA3 region
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DOI：
10.1113/jphysiol.2009.180851
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发表时间：
2010-03-01
影响因子：
5.5
通讯作者：
Paulsen, Ole
中科院分区：
文献类型：
--
作者：
Oren, Iris;Hajos, Norbert;Paulsen, Ole
在活跃网络状态期间，海马脑电图信号中的伽玛频率振荡（30-100 Hz）很突出。已在 CA3 区域发现了海马内伽马发生器。要了解振荡产生的机制，必须识别节律和电流发生器。虽然早期的工作已经阐明了节律产生的机制，但很少有人关注确定 CA3 伽马电流发生器。在这里，我们的目的是确定体外胆碱能诱导伽马频率振荡的电流发生器。为此，我们分析了金字塔层中记录的场电位振荡的小波振幅的瞬时波动，并同时记录了单个解剖学上识别的神经元的动作电位和突触输入。数据显示，锥体细胞中的体周抑制电流产生了大部分场电位。锥体细胞动作电流也对该领域做出了贡献。相反，我们没有发现任何证据表明激发电流对该模型中的场振荡有显着贡献。这里提出的场电位动态的即时分析提供了对突触电流和动作电流对脑电图信号的独特贡献的深入了解，并揭示了胆碱能诱导的伽马频率振荡期间兴奋和抑制的平衡变化。
Gamma frequency oscillations (30-100 Hz) are prominent in the hippocampal EEG signal during active network states. An intrahippocampal gamma generator has been identified in the CA3 region. To understand the mechanism of oscillation generation, both the rhythm and the current generators must be identified. While earlier work has elucidated mechanisms of rhythm generation, little attention has been given to identifying the CA3 gamma current generator. Here, we aimed to identify a current generator underlying cholinergically induced gamma frequency oscillations in vitro. To this end, we analysed the instantaneous fluctuations in the wavelet amplitude of the field potential oscillation recorded in the stratum pyramidale, and concomitantly recorded action potentials and synaptic input in individual, anatomically identified neurons. The data revealed that perisomatic inhibitory currents in pyramidal cells generated the majority of the field potential. Pyramidal cell action currents also contributed to the field. In contrast, we found no evidence that excitatory currents contribute significantly to the field oscillations in this model. The moment-by-moment analysis of the dynamics of the field potential presented here provides insight into the distinct contributions of synaptic and action currents to the EEG signal and sheds light on the changing balance of excitation and inhibition during cholinergically induced gamma frequency oscillations.