Abstract：
BACKGROUND: Prior work has shown that transcranial alternating current stimulation (tACS) of parietooccipital alpha oscillations (8-14 Hz) can modulate working memory (WM) performance as a function of the phase lag to endogenous oscillations. However, leveraging this effect using real-time phase-tuned tACS has not been feasible so far due to stimulation artifacts preventing continuous phase tracking.
OBJECTIVE: We aimed to develop a system that tracks and adapts the phase lag between tACS and ongoing parietooccipital alpha oscillations in real-time. We hypothesized that such real-time phase-tuned tACS enhances working memory performance, depending on the phase lag.
METHODS: We developed real-time phase-tuned closed-loop amplitude-modulated tACS (CLAM-tACS) targeting parietooccipital alpha oscillations. CLAM-tACS was applied at six different phase lags relative to ongoing alpha oscillations while participants (N = 21) performed a working memory task. To exclude that behavioral effects of CLAM-tACS were mediated by other factors such as sensory co-stimulation, a second group of participants (N = 25) received equivalent stimulation of the forehead.
RESULTS: WM accuracy improved in a phase lag dependent manner (p = 0.0350) in the group receiving parietooccipital stimulation, with the strongest enhancement observed at 330° phase lag between tACS and ongoing alpha oscillations (p = 0.00273, d = 0.976). Moreover, across participants, modulation of frontoparietal alpha oscillations correlated both in amplitude (p = 0.0248) and phase (p = 0.0270) with the modulation of WM accuracy. No such effects were observed in the control group receiving frontal stimulation.
CONCLUSIONS: Our results demonstrate the feasibility and efficacy of real-time phase-tuned CLAM-tACS in modulating both brain activity and behavior, thereby paving the way for further investigation into brain-behavior relationships and the exploration of innovative therapeutic applications.
OBJECTIVE: We aimed to develop a system that tracks and adapts the phase lag between tACS and ongoing parietooccipital alpha oscillations in real-time. We hypothesized that such real-time phase-tuned tACS enhances working memory performance, depending on the phase lag.
METHODS: We developed real-time phase-tuned closed-loop amplitude-modulated tACS (CLAM-tACS) targeting parietooccipital alpha oscillations. CLAM-tACS was applied at six different phase lags relative to ongoing alpha oscillations while participants (N = 21) performed a working memory task. To exclude that behavioral effects of CLAM-tACS were mediated by other factors such as sensory co-stimulation, a second group of participants (N = 25) received equivalent stimulation of the forehead.
RESULTS: WM accuracy improved in a phase lag dependent manner (p = 0.0350) in the group receiving parietooccipital stimulation, with the strongest enhancement observed at 330° phase lag between tACS and ongoing alpha oscillations (p = 0.00273, d = 0.976). Moreover, across participants, modulation of frontoparietal alpha oscillations correlated both in amplitude (p = 0.0248) and phase (p = 0.0270) with the modulation of WM accuracy. No such effects were observed in the control group receiving frontal stimulation.
CONCLUSIONS: Our results demonstrate the feasibility and efficacy of real-time phase-tuned CLAM-tACS in modulating both brain activity and behavior, thereby paving the way for further investigation into brain-behavior relationships and the exploration of innovative therapeutic applications.
摘要：
背景：先前的工作表明，上枕骨α振荡（8-14Hz）的经颅交流刺激（tACS）可以调节工作记忆（WM）性能，作为内源性振荡的相位滞后的函数。然而,利用使用实时相位调谐tACS的这种效果到目前为止还不可行，因为刺激伪影阻止了连续相位跟踪。
目的：我们旨在开发一种实时跟踪和适应tACS和正在进行的顶枕骨α振荡之间的相位滞后的系统。我们假设这种实时相位调谐tACS增强了工作记忆性能，取决于相位滞后。
方法：我们开发了针对顶枕骨α振荡的实时相位调谐闭环调幅tACS（CLAM-tACS）。在参与者（N=21）执行工作记忆任务时，相对于正在进行的alpha振荡，在六个不同的相位滞后下应用了CLAM-tACS。为了排除CLAM-tACS的行为效应是由其他因素介导的，例如感觉共刺激，第二组参与者(N=25)接受了相同的额头刺激.
结果：在接受顶枕骨刺激的组中，WM准确性以相位滞后的方式提高（p=0.0350），在tACS和正在进行的alpha振荡之间的330°相位滞后处观察到最强的增强（p=0.00273，d=0.976）。此外，跨参与者，额顶α振荡的调制在幅度（p=0.0248）和相位（p=0.0270）上都与WM精度的调制相关。在接受额叶刺激的对照组中未观察到此类影响。
结论：我们的结果证明了实时相位调谐CLAM-tACS在调节大脑活动和行为方面的可行性和有效性。从而为进一步研究大脑行为关系和探索创新治疗应用铺平了道路。
目的：我们旨在开发一种实时跟踪和适应tACS和正在进行的顶枕骨α振荡之间的相位滞后的系统。我们假设这种实时相位调谐tACS增强了工作记忆性能，取决于相位滞后。
方法：我们开发了针对顶枕骨α振荡的实时相位调谐闭环调幅tACS（CLAM-tACS）。在参与者（N=21）执行工作记忆任务时，相对于正在进行的alpha振荡，在六个不同的相位滞后下应用了CLAM-tACS。为了排除CLAM-tACS的行为效应是由其他因素介导的，例如感觉共刺激，第二组参与者(N=25)接受了相同的额头刺激.
结果：在接受顶枕骨刺激的组中，WM准确性以相位滞后的方式提高（p=0.0350），在tACS和正在进行的alpha振荡之间的330°相位滞后处观察到最强的增强（p=0.00273，d=0.976）。此外，跨参与者，额顶α振荡的调制在幅度（p=0.0248）和相位（p=0.0270）上都与WM精度的调制相关。在接受额叶刺激的对照组中未观察到此类影响。
结论：我们的结果证明了实时相位调谐CLAM-tACS在调节大脑活动和行为方面的可行性和有效性。从而为进一步研究大脑行为关系和探索创新治疗应用铺平了道路。
