Carrasco-Gómez Martín, García-Colomo Alejandra, Cabrera-Álvarez Jesús, Del Cerro-León Alberto, Gómez-Ariza Carlos J, Santos Andrés, Maestú Fernando
Department of Electronical Engineering, E.T.S. de Ingenieros de Telecomunicación, Universidad Politécnica de Madrid, Madrid, Spain.
Center for Cognitive and Computational Neuroscience, Complutense University of Madrid, Madrid, Spain.
Front Hum Neurosci. 2025 May 14;19:1534321. doi: 10.3389/fnhum.2025.1534321. eCollection 2025.
Research on the influence of transcranial alternating current stimulation over alpha functional connectivity (FC) is scarce, even when it poses as a potential treatment for various diseases. This study aimed to investigate the effects of individual alpha frequency tACS (IAF-tACS) on FC within the default mode network (DMN) in healthy individuals, particularly following the triple network model.
27 healthy participants were recruited, who underwent a 20-min IAF-tACS session over parieto-occipital areas and three magnetoencephalography (MEG) recordings: two pre-stimulation and one post-stimulation. Participants were randomly assigned to either the stimulation or sham group. Both dynamic FC (dFC) and static FC (sFC) were evaluated through the leakage corrected amplitude envelope correlation (AEC-c). Statistical analyses compared both Pre-Post FC ratio between groups through ratio -tests and intragroup FC changes through repeated measures -tests, with FDR correction applied to account for multiple comparisons. An additional analysis simulated the influence of the cortical folding on the effect of tACS over FC.
IAF-tACS significantly decreased sFC in intra- and inter-DMN links in the stimulation group compared to the sham group, with a special influence over antero-posterior links between hubs of the DMN. Negative correlations were found between AEC-c sFC changes and power alterations in posterior DMN areas, suggesting a complex interaction between cortical folding and electric field direction. On the other hand, dFC increased in both sham and stimulation groups, and no between-group differences were found.
Against our initial hypothesis, IAF-tACS reduced sFC in the DMN, possibly due to phase disparities introduced by cortical gyrification. These findings suggest that tACS might modulate FC in a more complex manner than previously thought, highlighting the need for further research into the personalized application of neuromodulation techniques, as well as its potential therapeutic implications for conditions like Alzheimer's disease.
尽管经颅交流电刺激对α功能连接（FC）的影响研究作为各种疾病的潜在治疗方法具有重要意义，但目前相关研究较少。本研究旨在探讨个体α频率经颅交流电刺激（IAF-tACS）对健康个体默认模式网络（DMN）内FC的影响，特别是基于三重网络模型进行研究。
招募了27名健康参与者，他们在顶枕区域接受了20分钟的IAF-tACS治疗，并进行了三次脑磁图（MEG）记录：两次刺激前记录和一次刺激后记录。参与者被随机分配到刺激组或假刺激组。通过泄漏校正幅度包络相关性（AEC-c）评估动态FC（dFC）和静态FC（sFC）。统计分析通过比率检验比较两组之间的刺激前后FC比率，并通过重复测量检验比较组内FC变化，应用错误发现率（FDR）校正以考虑多重比较。另外一项分析模拟了皮质折叠对tACS对FC影响的作用。
与假刺激组相比，刺激组中IAF-tACS显著降低了DMN内和DMN间连接的sFC，对DMN枢纽之间的前后连接有特别影响。在后脑DMN区域，AEC-c sFC变化与功率改变之间发现负相关，表明皮质折叠与电场方向之间存在复杂的相互作用。另一方面，假刺激组和刺激组的dFC均增加，且未发现组间差异。
与我们最初的假设相反，IAF-tACS降低了DMN中的sFC，这可能是由于皮质回旋引入的相位差异所致。这些发现表明，tACS对FC的调节方式可能比以前认为的更为复杂，这凸显了对神经调节技术个性化应用进行进一步研究的必要性，以及其对阿尔茨海默病等疾病的潜在治疗意义。
