Lim Rosary Yuting, Jiang Muyun, Ang Kai Keng, Lin Xiaohao, Guan Cuntai
Annu Int Conf IEEE Eng Med Biol Soc. 2024 Jul;2024:1-4. doi: 10.1109/EMBC53108.2024.10782251.
In this study, we introduce a novel brain-computer-brain (BCB) system to investigate the aftereffects of individualized, task-dependent transcranial alternating current stimulation (tACS) delivered to the motor cortex. While previous studies utilized either a generic stimulation frequency or matched it to an individual's resting frequency (e.g. individual alpha frequency, iAF), our study employed a trial-by-trial tACS stimulation design wherein the stimulation frequency delivered matches the individual's peak motor imagery (MI) performance frequency. 14 healthy subjects participated in both tACS and tACS-sham on separate days in a within-subject, randomized controlled design. We found that active tACS delivered to subjects receiving alpha (α)-tACS resulted in a decline in MI performance while that with tACS-sham did not differ significantly from baseline. However, subjects receiving beta (β)-tACS showed no significant difference in effect for both active tACS and tACS-sham conditions. These findings indirectly corroborated with that from literature advocating the notion of α tACS as functionally inhibitory; hence the consequential deterioration of MI performance observed only in α-tACS subjects. A more conclusive analysis will be conducted once more data is collected from this ongoing study.Clinical Relevance: The results gathered suggest the differential functional significance of α- and β-tACS in an individualized MI task-specific tACS delivery to the motor cortex with concurrent EEG recording. Although insignificant at the point of data analysis where sample size is small in this ongoing study, tACS-sham (30 Hz) seemed to potentially modulate neural oscillations in the direction of improving MI performance. These findings can inform future tACS study designs based on a system with personalized stimulation delivery for MI task investigations within laboratory and clinical settings - potentially beneficial towards upper limb stroke rehabilitation.
在本研究中，我们引入了一种新型脑-机-脑（BCB）系统，以研究向运动皮层施加个体化、任务依赖型经颅交流电刺激（tACS）后的效应。以往的研究要么采用通用的刺激频率，要么将其与个体的静息频率（如个体阿尔法频率，iAF）相匹配，而我们的研究采用了逐次试验的tACS刺激设计，其中施加的刺激频率与个体的运动想象（MI）峰值表现频率相匹配。14名健康受试者在不同日期分别参与了tACS和tACS伪刺激实验，采用受试者内随机对照设计。我们发现，接受阿尔法（α）-tACS的受试者在接受有源tACS时，MI表现下降，而接受tACS伪刺激的受试者与基线相比无显著差异。然而，接受贝塔（β）-tACS的受试者在有源tACS和tACS伪刺激条件下的效果均无显著差异。这些发现间接证实了文献中主张α-tACS具有功能抑制作用的观点；因此，仅在α-tACS受试者中观察到MI表现的相应恶化。一旦从这项正在进行的研究中收集到更多数据，将进行更具结论性的分析。临床意义：收集到的结果表明，在向运动皮层施加个体化MI任务特异性tACS并同步记录脑电图时，α-和β-tACS具有不同的功能意义。尽管在本正在进行的研究中，由于样本量小，在数据分析时不显著，但tACS伪刺激（30Hz）似乎有可能朝着改善MI表现的方向调节神经振荡。这些发现可为未来基于个性化刺激传递系统的tACS研究设计提供参考，用于实验室和临床环境中的MI任务研究——可能对上肢中风康复有益。
