Glinski Benedikt, Salehinejad Mohammed Ali, Takahashi Kuri, Jamil Asif, Yavari Fatemeh, Kuo Min-Fang, Nitsche Michael A
Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany.
Department of Psychology, Ruhr-University Bochum, Bochum, Germany.
Imaging Neurosci (Camb). 2025 Sep 10;3. doi: 10.1162/IMAG.a.140. eCollection 2025.
Gamma oscillations play a crucial role in core cognitive functions such as memory processes. Enhancing gamma oscillatory activity, which is reduced in Alzheimer's Disease, may have therapeutic potential, but effective interventions remain to be determined. Previous studies have shown that phase-synchronized electric and magnetic stimulation boosts brain oscillatory activities at theta, alpha, and delta frequency bands in different ways. The high-frequency gamma frequency band remains to be investigated. This study applies novel noninvasive brain stimulation techniques, namely phase-locked 40-Hz intermittent theta-burst stimulation (iTBS) and transcranial alternating current stimulation (tACS), and explores gamma oscillation changes in the brain. Thirty healthy young participants randomly underwent 40-Hz tACS (1), 40-Hz iTBS (2), two combined interventions (phase-locked iTBS to tACS peak sine wave or tACS trough sine wave) (3-4), and a sham condition (5). The target regions were the left and right dorsolateral prefrontal cortex and were stimulated by simultaneous tACS and iTBS. Gamma oscillatory activities (for 2 hours after intervention) were monitored following each intervention. Our results show that all stimulation protocols enhanced 40-Hz oscillatory power. The iTBS-tACS Peak shows the most significant and stable increase in gamma oscillatory activities (up to 2 hours), followed by 40-Hz tACS and 40-Hz iTBS. 40-Hz tACS and 40-Hz iTBS had the strongest acute effects (up to 30 minutes) on induced gamma oscillations, while 40-Hz tACS most consistently induced gamma oscillations for up to 2 hours in overall resting EEG data. Phase-synchronizing iTBS with tACS at 40 Hz and the very 40 Hz tACS alone targeting the dorsolateral prefrontal cortex may be a viable approach for inducing and stabilizing gamma oscillatory activity, particularly in conditions where endogenous gamma oscillations are attenuated, such as Alzheimer's Disease.
γ振荡在诸如记忆过程等核心认知功能中起着至关重要的作用。增强γ振荡活动（在阿尔茨海默病中该活动会降低）可能具有治疗潜力，但有效的干预措施仍有待确定。先前的研究表明，相位同步的电刺激和磁刺激以不同方式增强了大脑在θ、α和δ频段的振荡活动。高频γ频段仍有待研究。本研究应用了新颖的非侵入性脑刺激技术，即锁相40赫兹间歇性θ爆发刺激（iTBS）和经颅交流电刺激（tACS），并探索大脑中的γ振荡变化。30名健康的年轻参与者随机接受40赫兹tACS（1）、40赫兹iTBS（2）、两种联合干预（iTBS与tACS峰值正弦波或tACS谷值正弦波锁相）（3 - 4）以及假刺激条件（5）。目标区域是左右背外侧前额叶皮层，并通过同时进行的tACS和iTBS进行刺激。每次干预后监测γ振荡活动（干预后2小时内）。我们的结果表明，所有刺激方案均增强了40赫兹的振荡功率。iTBS - tACS峰值显示γ振荡活动有最显著且稳定的增加（长达2小时），其次是40赫兹tACS和40赫兹iTBS。40赫兹tACS和40赫兹iTBS对诱发的γ振荡具有最强的急性效应（长达30分钟），而在总体静息脑电图数据中，40赫兹tACS最持续地诱发γ振荡长达2小时。将40赫兹的iTBS与tACS相位同步以及单独使用40赫兹的tACS靶向背外侧前额叶皮层可能是诱导和稳定γ振荡活动的可行方法，特别是在诸如阿尔茨海默病等内源性γ振荡减弱的情况下。
