Ehrhardt Nina M, Hanna Jevri, Hayek Dayana, Fleischmann Robert, Grittner Ulrike, Thielscher Axel, Flöel Agnes, Antonenko Daria
Department of Neurology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße, 17475, Greifswald, Germany.
Berlin Institute of Health (BIH), Anna-Louisa-Karsch-Straße 2, 10178, Berlin, Germany.
Sci Rep. 2025 Jul 21;15(1):26504. doi: 10.1038/s41598-025-09841-y.
Targeting subcortical regions like the hippocampus with non-invasive brain stimulation is challenging due to predominantly cortical distribution of electric fields. Frontoparietal phase-synchronous transcranial alternating stimulation (tACS) offers a promising approach to modulate hippocampal functions, though its ability to induce modulation of oscillatory activity in deep subcortical targets remains to be shown. In this pilot study, we applied dual-site theta-tACS (in-phase between left frontoparietal regions) during a temporal order memory task. To quantify hippocampal activity and connectivity, we performed subcortical source analyses of electroencephalography (EEG) data using a hierarchical subspace pursuit algorithm. While memory did not differ between tACS and sham conditions, we observed tACS-induced increases in hippocampal theta power and its connectivity in individuals with superior memory performance. This study provides first-time evidence that phase-synchronized tACS over lateral frontoparietal areas influences hippocampal theta oscillatory activity, substantiating its potential to modulate hippocampal functions in health and disease.
由于电场主要分布在皮层，因此使用非侵入性脑刺激靶向海马体等皮层下区域具有挑战性。额顶叶相位同步经颅交变刺激（tACS）为调节海马体功能提供了一种有前景的方法，不过其在深部皮层下靶点诱导振荡活动调制的能力仍有待证实。在这项初步研究中，我们在一项时间顺序记忆任务期间应用了双位点θ-tACS（左额顶叶区域之间同相）。为了量化海马体活动和连通性，我们使用分层子空间追踪算法对脑电图（EEG）数据进行了皮层下源分析。虽然tACS和假刺激条件下的记忆没有差异，但我们观察到，在记忆表现优异的个体中，tACS诱导海马体θ波功率及其连通性增加。这项研究首次证明，外侧额顶叶区域的相位同步tACS会影响海马体θ振荡活动，证实了其在健康和疾病状态下调节海马体功能的潜力。
