Klimes Petr, Duque Juliano J, Jurak Pavel, Halamek Josef, Worrell Gregory A
Annu Int Conf IEEE Eng Med Biol Soc. 2015 Aug;2015:2191-4. doi: 10.1109/EMBC.2015.7318825.
Focal epileptic brain is characterized by a region of pathological tissue seizure onset zone (SOZ) - the pathologic tissue generating seizures. During the interictal period (nonseizure) the SOZ is characterized by epileptiform activity - interictal spikes & high-frequency oscillations (HFO). The SOZ also exhibits hyper-synchrony and functional disconnection from the surrounding areas. Recent studies have described the synchrony inside the SOZ and surrounding tissue for just small sets of patients (2-4) and without any distinction in behavioral states. Wake and sleep cycles can, however, have a significant influence on SOZ activity. Here we show the results of connectivity analysis in three fundamental areas of the epileptic brain - inside SOZ, outside SOZ and bridging areas in 7 patients during wake and sleep. We observed increased synchrony inside SOZ and decreased synchrony on its edges (bridging areas) in specific frequency bands. We also detected significant differences of synchrony levels between wake and sleep periods in HFO frequencies. Our results provide additional insight into the properties of SOZ connectivity. Knowledge of these principles may prove useful for SOZ localization and understanding epileptic brain function in general.
局灶性癫痫脑的特征是存在一个病理性组织区域，即癫痫发作起始区（SOZ）——产生癫痫发作的病理性组织。在发作间期（非发作期），SOZ的特征是癫痫样活动——发作间期棘波和高频振荡（HFO）。SOZ还表现出高度同步性以及与周围区域的功能断开。最近的研究仅针对少量患者（2 - 4例）描述了SOZ内部和周围组织的同步性，且未对行为状态进行任何区分。然而，清醒和睡眠周期会对SOZ活动产生重大影响。在此，我们展示了7例患者在清醒和睡眠期间，癫痫脑三个基本区域——SOZ内部、SOZ外部和连接区域的连通性分析结果。我们观察到在特定频段内，SOZ内部同步性增加，其边缘（连接区域）同步性降低。我们还检测到HFO频率在清醒和睡眠期间同步水平的显著差异。我们的结果为SOZ连通性的特性提供了更多见解。了解这些原理可能对SOZ定位以及总体上理解癫痫脑功能有用。
