Hertie Institute for Clinical Brain Research, University Medical Center Tübingen, Tübingen 72076, Germany.
Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, Tübingen 72076, Germany.
eNeuro. 2024 Sep 4;11(9). doi: 10.1523/ENEURO.0242-24.2024. Print 2024 Sep.
Generalized epilepsy (GE) encompasses a heterogeneous group of hyperexcitability disorders that clinically manifest as seizures. At the whole-brain level, distinct seizure patterns as well as interictal epileptic discharges (IEDs) reflect key signatures of hyperexcitability in magneto- and electroencephalographic (M/EEG) recordings. Moreover, it had been suggested that aperiodic activity, specifically the slope of the 1/ decay function of the power spectrum, might index neural excitability. However, it remained unclear if hyperexcitability as encountered at the cellular level directly translates to putative large-scale excitability signatures, amenable to M/EEG. In order to test whether the power spectrum is altered in hyperexcitable states, we recorded resting-state MEG from male and female GE patients ( = 51; 29 females; 28.82 ± 12.18 years; mean ± SD) and age-matched healthy controls ( = 49; 22 females; 32.10 ± 12.09 years). We parametrized the power spectra using FOOOF ("fitting oscillations and one over ") to separate oscillatory from aperiodic activity to directly test whether aperiodic activity is systematically altered in GE patients. We further identified IEDs to quantify the temporal dynamics of aperiodic activity around overt epileptic activity. The results demonstrate that aperiodic activity indexes hyperexcitability in GE at the whole-brain level, especially during epochs when no IEDs were present ( = 0.0130; = 0.52). Upon IEDs, large-scale circuits transiently shifted to a less excitable network state ( = 0.001; = 0.68). In sum, these results uncover that MEG background activity might index hyperexcitability based on the current brain state and does not rely on the presence of epileptic waveforms.
全面性癫痫（GE）包含一大组兴奋性障碍疾病，这些疾病在临床上表现为癫痫发作。在全脑水平上，不同的癫痫发作模式以及发作间期癫痫样放电（IEDs）反映了磁和脑电图（M/EEG）记录中兴奋性过高的关键特征。此外，有人提出非周期性活动，特别是功率谱 1/衰减函数的斜率，可能反映神经兴奋性。然而，尚不清楚细胞水平上的兴奋性过高是否直接转化为可用于 M/EEG 的潜在的大尺度兴奋性特征。为了测试在兴奋性过高状态下功率谱是否发生改变，我们记录了男性和女性 GE 患者（ = 51；29 名女性；28.82 ± 12.18 岁；均值 ± 标准差）以及年龄匹配的健康对照组（ = 49；22 名女性；32.10 ± 12.09 岁）的静息态 MEG。我们使用 FOOOF（“拟合振荡和一个以上”）对功率谱进行参数化，以分离振荡和非周期性活动，从而直接测试 GE 患者的非周期性活动是否系统地发生改变。我们进一步确定了 IEDs，以量化在明显癫痫活动周围的非周期性活动的时间动态。结果表明，非周期性活动在全脑水平上反映了 GE 的兴奋性过高，特别是在没有 IEDs 存在的时期（ = 0.0130； = 0.52）。在 IEDs 出现时，大尺度电路暂时转移到兴奋性较低的网络状态（ = 0.001； = 0.68）。总之，这些结果揭示了 MEG 背景活动可能基于当前的大脑状态来反映兴奋性过高，而不依赖于癫痫波形的存在。
