Recovering steady‐state visual evoked potential‐related electroencephalography during amplitude‐modulated‐transcranial alternating current stimulation using dynamic adaptive stimulation artifact source separation

Abstract

Simultaneous electroencephalography (EEG) recording during transcranial alternating current stimulation (tACS) is strongly contaminated by stimulation artifacts, limiting direct assessment of neural activity. Steady‐state visual evoked potentials (SSVEPs) provide frequency‐specific and phase‐locked responses, making them suitable for validating task‐related EEG recovery. This study evaluated whether dynamic adaptive stimulation artifact source separation (DASASS) can recover task‐related EEG during amplitude‐modulated tACS (AM‐tACS), using SSVEPs as a validation paradigm. Fourteen healthy participants completed SSVEP experiments under no‐stimulation and AM‐tACS conditions. No‐stimulation EEG served as the artifact‐free reference, whereas AM‐tACS EEG was analyzed before and after DASASS processing as artifact‐contaminated and DASASS‐recovered signals, respectively. Recovery performance was quantified in the time, frequency, and phase domains using amplitude‐ratio error, spectral correlation, and phase concentration error. DASASS‐recovered EEG showed waveform patterns closer to the artifact‐free reference across stimulation frequencies. Time‐domain amplitude‐ratio error was significantly reduced at all nine frequencies. In the frequency domain, DASASS produced higher spectral correlation with artifact‐free EEG at 8.5, 10, 10.5, 11, 11.5, and 12 Hz. In the phase domain, phase concentration error was reduced at 9 and 9.5 Hz. These findings indicate that DASASS suppresses AM‐tACS artifacts while preserving key features of task‐related SSVEP responses, supporting direct analysis of task‐related brain dynamics during AM‐tACS.