Impact of Electrode Drift in Multi-Electrode Temporal Interference Stimulation

Drift in electrode position during a session of transcranial direct current stimulation (tDCS) produces significant alteration in the intensity of stimulation delivered to the brain. However, the impact of electrode position drift remains unclear on temporal interference stimulation (TIS), which is a novel method for noninvasive deep brain stimulation utilizing two high-frequency alternating current signals (≥1 kHz). In this study, we investigated the impact of electrode drift in four directions on multi-electrode TIS based on the electrode montage obtained by our optimization paradigm. Moreover, the impact of TIS with different electrode numbers was evaluated in the same electrode drift. Our findings show that electrode drifts in any direction have comparable impacts on TIS, with larger impacts observed for drifts exceeding 10 mm. Furthermore, the influence of electrode drift increases with the number of electrodes. A 5mm offset under 16 electrodes has a similar impact to a 15mm offset under 4 electrodes. The above findings suggest that electrode offset has a significant impact on TIS, which may affect the clinical efficacy of TIS. Meanwhile, controlling the electrode offset below 5mm has the potential to enhance the effectiveness of TIS when using multi-electrode TIS.