Salami Pariya, Lévesque Maxime, Benini Ruba, Behr Charles, Gotman Jean, Avoli Massimo
Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada.
Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada.
Neurobiol Dis. 2014 Jul;67:97-106. doi: 10.1016/j.nbd.2014.03.012. Epub 2014 Mar 28.
Mesial temporal lobe epilepsy (MTLE) is characterized in humans and in animal models by a seizure-free latent phase that follows an initial brain insult; this period is presumably associated to plastic changes in temporal lobe excitability and connectivity. Here, we analyzed the occurrence of interictal spikes and high frequency oscillations (HFOs; ripples: 80-200Hz and fast ripples: 250-500Hz) from 48h before to 96h after the first seizure in the rat pilocarpine model of MTLE. Interictal spikes recorded with depth EEG electrodes from the hippocampus CA3 area and entorhinal cortex (EC) were classified as type 1 (characterized by a spike followed by a wave) or type 2 (characterized by a spike with no wave). We found that: (i) there was a switch in the distribution of both types of interictal spikes before and after the occurrence of the first seizure; during the latent phase both types of interictal spikes predominated in the EC whereas during the chronic phase both types of spikes predominated in CA3; (ii) type 2 spike duration decreased in both regions from the latent to the chronic phase; (iii) type 2 spikes associated to fast ripples occurred at higher rates in EC compared to CA3 during the latent phase while they occurred at similar rates in both regions in the chronic phase; and (iv) rates of fast ripples outside of spikes were higher in EC compared to CA3 during the latent phase. Our findings demonstrate that the transition from the latent to the chronic phase is paralleled by dynamic changes in interictal spike and HFO expression in EC and CA3. We propose that these changes may represent biomarkers of epileptogenicity in MTLE.
内侧颞叶癫痫（MTLE）在人类和动物模型中的特征是，在最初的脑部损伤后会出现一个无癫痫发作的潜伏期；这个时期可能与颞叶兴奋性和连接性的可塑性变化有关。在此，我们分析了MTLE大鼠匹鲁卡品模型中首次癫痫发作前48小时至发作后96小时期间发作间期棘波和高频振荡（HFOs；涟漪：80 - 200Hz和快速涟漪：250 - 500Hz）的发生情况。用深度脑电图电极从海马CA3区和内嗅皮质（EC）记录的发作间期棘波被分类为1型（特征为一个棘波后跟随一个波）或2型（特征为一个无波的棘波）。我们发现：（i）在首次癫痫发作前后，两种类型的发作间期棘波的分布发生了转变；在潜伏期，两种类型的发作间期棘波在EC中占主导，而在慢性期，两种类型的棘波在CA3中占主导；（ii）从潜伏期到慢性期，两个区域的2型棘波持续时间均缩短；（iii）与快速涟漪相关的2型棘波在潜伏期EC中的发生率高于CA3，而在慢性期两个区域的发生率相似；（iv）在潜伏期，EC中棘波外的快速涟漪发生率高于CA3。我们的研究结果表明，从潜伏期到慢性期的转变伴随着EC和CA3中发作间期棘波和HFO表达的动态变化。我们提出这些变化可能代表MTLE中癫痫发生的生物标志物。
