Alpha-frequency transcranial alternating current stimulation (α-tACS) applied to the cortical source of alpha oscillations in healthy adults not only increased EEG alpha activity but also strengthened functional connectivity within the default mode network (DMN), with the alpha increase mediating the connectivity enhancement. The findings identify a mechanistic link between alpha oscillations and DMN functioning and highlight α-tACS as a noninvasive intervention to regulate the DMN, which is dysregulated in major neuropsychiatric disorders.
Stimulating the brain's alpha oscillations with a non-invasive technique called high-definition alpha-frequency transcranial alternating current stimulation (α-tACS) strengthened the default mode network (DMN), a key brain network involved in self-reflection and mind-wandering. Compared to a sham control, α-tACS increased both EEG alpha oscillations and fMRI connectivity within the core of the DMN. The increase in alpha activity mediated the enhancement of DMN connectivity. These results identify a mechanistic link between alpha oscillations and DMN functioning and suggest that α-tACS could be an effective non-invasive intervention for normalizing DMN dysregulation in neuropsychiatric disorders.