Bragin Anatol, Wilson Charles L, Almajano Joyel, Mody Istvan, Engel Jerome
Department of Neurology, UCLA School of Medicine, Los Angeles, California 90095, USA.
Epilepsia. 2004 Sep;45(9):1017-23. doi: 10.1111/j.0013-9580.2004.17004.x.
To investigate the temporal relation between high-frequency oscillations (HFOs) in the dentate gyrus and recurrent spontaneous seizures after intrahippocampal kainite-induced status epilepticus.
Recording microelectrodes were implanted bilaterally in different regions of hippocampus and entorhinal cortex. A guide cannula for microinjection of kainic acid (KA) was implanted above the right posterior CA3 area of hippocampus. After recording baseline electrical activity, KA (0.4 microg/0.2 microl) was injected. Beginning on the next day, electrographic activity was recorded with video monitoring for seizures every day for 8 h/day for > or = 30 days.
Of the 26 rats studied, 19 revealed the appearance of sharp-wave activity and HFOs in the frequency range of 80 to 500 Hz in the dentate gyrus ipsilateral to the KA injection. In the remaining seven rats, no appreciable activity was noted in this frequency range. In some rats with recurrent seizures, HFOs were in the ripple frequency range (100-200 Hz); in others, HFOs were in the fast ripple frequency range (200-500 Hz), or a mixture of both oscillation frequencies was found. The time of detection of the first HFOs after status epilepticus varied between 1 and 30 days, with a mean of 6.3 +/- 2.0 (SEM). Of the 19 rats in which HFO activity appeared, all later developed recurrent spontaneous seizures, whereas none of the rats without HFOs developed seizures. The sooner HFO activity was detected after status epilepticus, the sooner the first spontaneous seizure occurred. A significant inverse relation was found between the time to the first HFO detection and the subsequent rate of spontaneous seizures.
A strong correlation was found between a decreased time to detection of HFOs and an increased rate of spontaneous seizures, as well as with a decrease in the duration of the latent period between KA injection and the detection of spontaneous seizures. Two types of HFOs were found after KA injection, one in the frequency range of 100 to 200 Hz, and the other, in the frequency range of 200 to 500 Hz, and both should be considered pathological, suggesting that both are epileptogenic.
研究海马内注射红藻氨酸诱导癫痫持续状态后齿状回高频振荡（HFOs）与复发性自发性癫痫发作之间的时间关系。
将记录微电极双侧植入海马和内嗅皮质的不同区域。在海马右后CA3区上方植入用于微量注射红藻氨酸（KA）的引导套管。记录基线电活动后，注射KA（0.4微克/0.2微升）。从第二天开始，每天进行8小时的视频监测记录脑电图活动，持续≥30天以观察癫痫发作。
在研究的26只大鼠中，19只在KA注射侧齿状回出现了尖锐波活动以及80至500赫兹频率范围内的HFOs。其余7只大鼠在该频率范围内未观察到明显活动。在一些复发性癫痫发作的大鼠中，HFOs处于涟漪频率范围（100 - 200赫兹）；在另一些大鼠中，HFOs处于快速涟漪频率范围（200 - 500赫兹），或者发现两种振荡频率混合存在。癫痫持续状态后首次检测到HFOs的时间在1至30天之间，平均为6.3±2.0（标准误）。在出现HFO活动的19只大鼠中，所有大鼠后来都出现了复发性自发性癫痫发作，而没有HFOs的大鼠均未出现癫痫发作。癫痫持续状态后越早检测到HFO活动，首次自发性癫痫发作就越早出现。首次检测到HFO的时间与随后的自发性癫痫发作率之间存在显著的负相关。
发现检测到HFOs的时间缩短与自发性癫痫发作率增加以及KA注射与检测到自发性癫痫发作之间潜伏期的持续时间缩短之间存在强烈相关性。KA注射后发现两种类型的HFOs，一种在1
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