Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands; Maastricht Brain Imaging Centre (MBIC), Maastricht, Netherlands.
Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands; Language and Computation in Neural Systems Group, Max Planck Institute for Psycholinguistics, Nijmegen, Netherlands; Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, Netherlands.
Neuroimage. 2022 Jun;253:119109. doi: 10.1016/j.neuroimage.2022.119109. Epub 2022 Mar 16.
Transcranial alternating current stimulation (tACS) can be used to study causal contributions of oscillatory brain mechanisms to cognition and behavior. For instance, individual alpha frequency (IAF) tACS was reported to enhance alpha power and impact visuospatial attention performance. Unfortunately, such results have been inconsistent and difficult to replicate. In tACS, stimulation generally involves one frequency, sometimes individually calibrated to a peak value observed in an M/EEG power spectrum. Yet, the 'peak' actually observed in such power spectra often contains a broader range of frequencies, raising the question whether a biologically calibrated tACS protocol containing this fuller range of alpha-band frequencies might be more effective. Here, we introduce 'Broadband-alpha-tACS', a complex individually calibrated electrical stimulation protocol. We band-pass filtered left posterior resting-state EEG data around the IAF (± 2 Hz), and converted that time series into an electrical waveform for tACS stimulation of that same left posterior parietal cortex location. In other words, we stimulated a brain region with a 'replay' of its own alpha-band frequency content, based on spontaneous activity. Within-subjects (N = 24), we compared to a sham tACS session the effects of broadband-alpha tACS, power-matched spectral inverse ('alpha-removed') control tACS, and individual alpha frequency (IAF) tACS, on EEG alpha power and performance in an endogenous attention task previously reported to be affected by alpha tACS. Broadband-alpha-tACS significantly modulated attention task performance (i.e., reduced the rightward visuospatial attention bias in trials without distractors, and reduced attention benefits). Alpha-removed tACS also reduced the rightward visuospatial attention bias. IAF-tACS did not significantly modulate attention task performance compared to sham tACS, but also did not statistically significantly differ from broadband-alpha-tACS. This new broadband-alpha-tACS approach seems promising, but should be further explored and validated in future studies.
经颅交流电刺激（tACS）可用于研究振荡脑机制对认知和行为的因果贡献。例如，个体阿尔法频率（IAF）tACS 被报道能增强阿尔法功率并影响视觉空间注意表现。不幸的是，这些结果一直不一致且难以复制。在 tACS 中，刺激通常涉及一个频率，有时根据 M/EEG 功率谱中观察到的峰值进行单独校准。然而，在这种功率谱中观察到的“峰值”实际上包含更广泛的频率范围，这就提出了一个问题，即是否含有更广泛的阿尔法频带频率的生物校准 tACS 方案可能更有效。在这里，我们引入了“宽带阿尔法 tACS”，这是一种复杂的个体校准电刺激方案。我们在 IAF（±2Hz）周围对左后静息状态 EEG 数据进行带通滤波，并将该时间序列转换为同一左后顶叶皮层位置的 tACS 刺激的电波形。换句话说，我们根据自发活动，用大脑自身的阿尔法频带频率内容的“回放”来刺激一个脑区。在被试内（N=24），我们将宽带阿尔法 tACS 与假 tACS 会话、功率匹配的频谱反转（“去除阿尔法”）对照 tACS 以及个体阿尔法频率（IAF）tACS 进行了比较，以评估它们对先前报道的受阿尔法 tACS 影响的内源性注意任务中的 EEG 阿尔法功率和表现的影响。宽带阿尔法 tACS 显著调节了注意任务的表现（即，在没有分心物的试验中减少了右向视觉空间注意偏差，并减少了注意收益）。去除阿尔法的 tACS 也减少了右向视觉空间注意偏差。与 sham tACS 相比，IAF-tACS 对注意任务的表现没有显著调节作用，但也没有与宽带阿尔法 tACS 显著不同。这种新的宽带阿尔法 tACS 方法似乎很有前途，但应在未来的研究中进一步探索和验证。
