Effective seizure control remains challenging for about 30% of epilepsy patients who are resistant to present-day pharmacotherapy. Novel approaches that not only reduce the severity and frequency of seizures, but also have limited side effects are therefore desirable. Accordingly, various neuromodulation approaches such as cortical electrical stimulation have been implemented to reduce seizure burden; however, the underlying mechanisms are not completely understood. Given that the initiation and spread of epileptic seizures critically depend on cortical excitability, understanding the neuromodulatory effects of cortical electrical stimulation on cortical excitability levels is paramount. Based on observations that synchronization in the electrocorticogram closely tracks brain excitability level, the effects of low-frequency (1 Hz) intracranial brain stimulation on the levels of cortical phase synchronization before, during, and after 1 Hz electrical stimulation were assessed in twelve patients. Analysis of phase synchronization levels across three broad frequency bands (1–45 Hz, 55–95 Hz, and 105–195 Hz) revealed that in patients with stimulation sites in the neocortex, phase synchronization levels were significantly reduced within the 55–95 Hz and 105–195 Hz bands during post-stimulation intervals compared to baseline; this effect persisted for at least 30 min post-stimulation. Similar effects were observed when phase synchronization levels were examined in the classic frequency bands, whereby a significant reduction was found during the post-stimulation intervals in the alpha, beta, and gamma bands. The anatomical extent of these effects was then assessed. Analysis of the results from six patients with intracranial electrodes in both hemispheres indicated that reductions in phase synchronization in the 1–45 Hz and 55–95 Hz frequency ranges were more prominent in the stimulated hemisphere. Overall, these findings demonstrate that low-frequency electrical stimulation reduces phase synchronization and hence cortical excitability in the human brain. Low-frequency stimulation of the epileptic focus may therefore contribute to the prevention of impending epileptic seizures.

对于约 30% 对现有药物治疗有抵抗力的癫痫患者来说，有效控制癫痫发作仍然具有挑战性。因此，人们需要新的方法，不仅可以降低癫痫发作的严重程度和频率，而且副作用也有限。因此，已经实施了各种神经调节方法（例如皮质电刺激）来减轻癫痫发作负担；然而，其根本机制尚未完全了解。鉴于癫痫发作的发生和扩散很大程度上取决于皮质兴奋性，了解皮质电刺激对皮质兴奋性水平的神经调节作用至关重要。基于皮层电图中的同步密切跟踪大脑兴奋性水平的观察，低频 (1 Hz) 颅内脑刺激对 12 名患者在 1 Hz 电刺激之前、期间和之后的皮质相位同步水平的影响进行了评估。对三个宽频带（1-45 Hz、55-95 Hz 和 105-195 Hz）的相位同步水平的分析表明，在新皮质部位受到刺激的患者中，相位同步水平在 55-95 Hz 范围内显着降低。与基线相比，刺激后间隔期间为 105–195 Hz 频段；这种效果在刺激后持续至少 30 分钟。当在经典频段中检查相位同步水平时，观察到类似的效果，从而在 α、β 和 γ 频段的刺激后间隔期间发现显着降低。然后评估这些影响的解剖范围。对六名在两个半球均装有颅内电极的患者的结果进行的分析表明，在受刺激的半球中，1-45 Hz 和 55-95 Hz 频率范围内的相位同步降低更为明显。总的来说，这些发现表明低频电刺激会降低相位同步性，从而降低人脑皮质的兴奋性。因此，低频刺激癫痫病灶可能有助于预防即将发生的癫痫发作。