ISR-Lisboa/LARSyS and Department of Bioengineering, Instituto Superior Técnico - Universidade de Lisboa, Portugal.
Department of Neurophysiology, Centro Hospitalar Psiquiátrico de Lisboa, Lisbon, Portugal.
Clin Neurophysiol. 2018 Mar;129(3):618-635. doi: 10.1016/j.clinph.2017.12.038. Epub 2018 Jan 11.
We hypothesize that the hypersynchronization associated with epileptic activity is best described by EEG synchronization measures, and propose to use these as predictors of epilepsy-related BOLD fluctuations.
We computed the phase synchronization index (PSI) and global field synchronization (GFS), within two frequency bands, a broadband (1-45 Hz) and a narrower band focused on the presence of epileptic activity (3-10 Hz). The associated epileptic networks were compared with those obtained using conventional unitary regressors and two power-weighted metrics (total power and root mean square frequency), on nine simultaneous EEG-fMRI datasets from four epilepsy patients, exhibiting inter-ictal epileptiform discharges (IEDs).
The average PSI within 3-10 Hz achieved the best performance across several measures reflecting reliability in all datasets. The results were cross-validated through electrical source imaging of the IEDs. The applicability of PSI when no IEDs are recorded on the EEG was evaluated on three additional patients, yielding partially plausible networks in all cases.
Epileptic networks can be mapped based on the EEG PSI metric within an IED-specific frequency band, performing better than commonly used EEG metrics.
This is the first study to investigate EEG synchronization measures as potential predictors of epilepsy-related BOLD fluctuations.
我们假设与癫痫活动相关的过度同步性可以通过 EEG 同步测量来最好地描述，并提出将这些测量用作癫痫相关 BOLD 波动的预测因子。
我们在两个频带内计算了相位同步指数 (PSI) 和全局场同步 (GFS)，一个宽带 (1-45 Hz) 和一个更窄的频带专门针对癫痫活动的存在 (3-10 Hz)。将相关的癫痫网络与使用传统单元回归器和两种功率加权指标（总功率和均方根频率）在来自四个癫痫患者的九个同时 EEG-fMRI 数据集上获得的网络进行了比较，这些患者表现出间歇性癫痫样放电 (IEDs)。
在几个反映所有数据集可靠性的指标中，3-10 Hz 范围内的平均 PSI 表现最佳。通过对 IED 的电源成像对结果进行了交叉验证。在另外三个没有在 EEG 上记录 IED 的患者上评估了 PSI 的适用性，在所有情况下都产生了部分合理的网络。
可以根据 IED 特定频带内的 EEG PSI 指标来绘制癫痫网络，其性能优于常用的 EEG 指标。
这是第一项研究，旨在调查 EEG 同步测量作为癫痫相关 BOLD 波动的潜在预测因子的可能性。
