Borisiuk R M
Institute of Mathematical Problems in Biology, Russian Academy of Sciences, Pushchino.
Zh Vyssh Nerv Deiat Im I P Pavlova. 2004 Jan-Feb;54(1):85-100.
Centre of Theoretical and Computational Neuroscience, University of Plymouth, UK Basing on the hypothesis about the mechanisms of the theta rhythm generation, the article presents mathematical and computational models of theta activity in the hippocampus. The problem of the theta rhythm modeling is nontrivial because the slow theta oscillations (about 5 Hz) should be generated by a neural system composed of frequently firing neural populations. We studied a model of neural pacemakers in the septum. In this model, the pacemaker follows the frequency of the external signal if this frequency does not deviate too far from the natural frequency of the pacemaker, otherwise the pacemaker returns to the frequency of its own oscillations. These results are in agreement with the experimental records of medial septum neurons. Our model of the septal pacemaker of the theta rhythm is based on the hypothesis that the hippocampal theta appears as a result of the influence of the assemblies of neurons in the medial septum which are under control of pacemaker neurons. Though the model of the pacemaker satisfies many experimental facts, the synchronization of activity in different neural assemblies of the model is not as strong as it should be. Another model of the theta generation is based on the anatomical data about the existence of the inhibitory GABAergic loop between the medial septum and the hippocampus. This model shows stable oscillations at the frequency of the theta rhythm in a broad range of parameter values. It also provides explanation to the experimental data about the variation of the frequency and the amplitude of the theta rhythm under different external stimulations of the system. The role of the theta rhythm for information processing in the hippocampus is discussed.
英国普利茅斯大学理论与计算神经科学中心 基于关于θ节律产生机制的假设，本文提出了海马体中θ活动的数学和计算模型。θ节律建模问题并不简单，因为缓慢的θ振荡（约5赫兹）应由由频繁放电的神经群体组成的神经系统产生。我们研究了隔区神经起搏器模型。在这个模型中，如果外部信号的频率与起搏器的自然频率偏差不太大，起搏器就会跟随外部信号的频率，否则起搏器会恢复到自身振荡频率。这些结果与内侧隔区神经元的实验记录一致。我们的θ节律隔区起搏器模型基于这样的假设：海马体θ是由内侧隔区受起搏器神经元控制的神经元集合的影响而出现的。尽管起搏器模型符合许多实验事实，但模型中不同神经集合的活动同步性并不像预期的那么强。另一种θ产生模型基于关于内侧隔区和海马体之间存在抑制性GABA能环路的解剖学数据。该模型在广泛的参数值范围内显示出稳定的θ节律频率振荡。它还对系统在不同外部刺激下θ节律频率和振幅变化的实验数据提供了解释。文中讨论了θ节律在海马体信息处理中的作用。
