Li Xiaoli, Jefferys John G R, Fox John, Yao Xin
Institute of Electrical Engineering, Yanshan University, 066004, China.
Neural Netw. 2008 Oct;21(8):1105-11. doi: 10.1016/j.neunet.2008.06.002. Epub 2008 Jun 22.
Neuronal population oscillations in the hippocampus have an important effect in the information processing in the brain and the generation of epileptic seizures. In this paper, we investigate the neuronal population oscillations in the hippocampus of epileptic rats in vivo using an empirical mode decomposition (EMD) method. A neuronal population oscillation can be decomposed into several relaxation oscillations, which possess a recovery and release phase, with the different frequencies that ranges from 0 to 600 Hz. The natures of relaxation oscillations at the pre-ictal, seizure onset and ictal states are distinctly different. The analysis of relaxation oscillations show that the gamma wave is a lead relaxation oscillation at the pre-ictal stage, then it moves to beta oscillation or theta oscillation while the ictal stage starts; the fast relaxation oscillations are associated with the slow relaxation oscillations in the CA1 or CA3, in particular, the fast relaxation oscillations are associated on the recovery phase of the slow relaxation oscillations during the pre-ictal interval, however move to the release phase of the slow relaxation oscillations during the ictal interval. Comparison of the relaxation oscillations in CA1 and CA3 shows that the neurons in the CA1 are more active during the epileptic seizures than during the pre-ictal stage. These findings demonstrate that this method is very helpful to decompose neuronal population for understanding the underlying mechanism of epileptic seizures.
海马体中的神经元群体振荡对大脑中的信息处理以及癫痫发作的产生具有重要影响。在本文中，我们使用经验模态分解（EMD）方法对癫痫大鼠海马体中的神经元群体振荡进行了体内研究。神经元群体振荡可分解为几个弛豫振荡，这些弛豫振荡具有恢复和释放阶段，频率范围为0至600赫兹。发作前、发作开始和发作期的弛豫振荡性质明显不同。对弛豫振荡的分析表明，γ波在发作前阶段是主导弛豫振荡，然后在发作阶段开始时转变为β振荡或θ振荡；快速弛豫振荡与CA1或CA3中的慢速弛豫振荡相关，特别是在发作前间隔期间，快速弛豫振荡与慢速弛豫振荡的恢复阶段相关，但在发作期间则转变为慢速弛豫振荡的释放阶段。CA1和CA3中弛豫振荡的比较表明，癫痫发作期间CA1中的神经元比发作前阶段更活跃。这些发现表明，该方法对于分解神经元群体以理解癫痫发作的潜在机制非常有帮助。
