Jones Ryan T, Barth Albert M, Ormiston Laurel D, Mody Istvan
Department of Neurobiology Graduate Program, The David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, U.S.A.
Department of Neurology, The David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, U.S.A.
Epilepsia. 2015 Dec;56(12):1879-89. doi: 10.1111/epi.13218. Epub 2015 Oct 30.
In temporal lobe epilepsy (TLE), pathologic high frequency oscillations (pHFOs, 200-600 Hz) are present in the hippocampus, especially the dentate gyrus (DG). The pHFOs emerge during a latent period prior to the onset of spontaneous generalized seizures. We used a unilateral suprahippocampal injection of kainic acid (KA) mouse model of TLE to characterize the properties of hippocampal pHFOs during epileptogenesis.
In awake head-fixed mice, 4-14 days after KA-induced status epilepticus (SE), we recorded local field potentials (LFPs) with 64-channel silicon probes spanning from CA1 alveus to the DG hilus, or with glass pipettes in the DC mode in the CA1 str radiatum.
The pHFOs, are observed simultaneously in the CA1 and the DG, or in the DG alone, as early as 4 days post-SE. The pHFOs ride on top of DC deflections, occur during motionless periods, persist through the onset of TLE, and are generated in bursts. Burst parameters remain remarkably constant during epileptogenesis, with a random number of pHFOs generated per burst. In contrast, pHFO duration and spectral dynamics evolve from short events at 4 days post-SE to prolonged discharges with complex spectral characteristics by 14 days post-SE. Simultaneous dural EEG recordings were exceedingly unreliable for detecting hippocampal pHFOs; therefore, such recordings may deceptively indicate a "silent" period even when massive hippocampal activity is present.
Our results demonstrate that hippocampal pHFOs exhibit a dynamic evolution during the epileptogenic period following SE, consistent with their role in transitioning to the chronic stage of TLE.
在颞叶癫痫（TLE）中，病理性高频振荡（pHFOs，200 - 600Hz）存在于海马体中，尤其是齿状回（DG）。pHFOs在自发性全身性癫痫发作开始前的潜伏期出现。我们使用单侧海马体上注射 kainic 酸（KA）的TLE小鼠模型来表征癫痫发生过程中海马体pHFOs的特性。
在清醒的头部固定小鼠中，KA诱导的癫痫持续状态（SE）后4 - 14天，我们用64通道硅探针从CA1海马槽记录到DG门区的局部场电位（LFPs），或在CA1辐射层以直流模式用玻璃微电极记录。
早在SE后4天，就在CA1和DG中同时观察到pHFOs，或者仅在DG中观察到。pHFOs叠加在直流偏转之上，在静止期出现，持续到TLE发作，并以突发形式产生。在癫痫发生过程中，突发参数保持显著恒定，每次突发产生的pHFOs数量随机。相比之下，pHFO持续时间和频谱动态从SE后4天的短事件演变为SE后14天具有复杂频谱特征的延长放电。同时进行的硬脑膜脑电图记录对于检测海马体pHFOs极其不可靠；因此，即使存在大量海马体活动，此类记录可能会误导性地显示一个“静止”期。
我们的结果表明，海马体pHFOs在SE后的癫痫发生期表现出动态演变，这与其在向TLE慢性阶段转变中的作用一致。
