Enhancing Deep Brain Entrainment With Pulse Wave Temporal Interference Stimulation: A Comparative Study of Carrier...

Transcranial temporal interference stimulation (tTIS) is a novel noninvasive neuromodulation technique that uses high-frequency carrier waves to entrain low-frequency envelope oscillations in deep brain regions. Although conventional tTIS mainly uses sine waves as carriers, the effectiveness of alternative waveforms, such as pulse waves, is poorly understood. This study aimed to compare the effects of sine and pulse wave carriers in tTIS on neural activity within deep brain structures.

In this study, we used a minipig model implanted with deep brain electrodes to apply tTIS using either sine or pulse wave carriers. We recorded local field potentials (LFPs) to evaluate neural entrainment. The maximum stimulation intensity was set at 2V. Our analysis focused on comparing the stimulus-response relationships, evaluating the effects of different carrier frequencies, and assessing the range of entrained envelope oscillations for both sine and pulse wave tTIS.

Both sine and pulse wave tTIS generated comparable envelope oscillations in the deep brain. The relationship between stimulus intensity and LFP response followed a log-normal distribution for both waveforms. When carrier frequencies in the kilohertz range effectively generated envelope entrainment, envelope frequencies below 300 Hz also had measurable effects. Notably, pulse wave stimulation yielded a stronger envelope power spectrum.

Pulse and sine waves are both effective carriers for tTIS, with pulse waves providing practical advantages owing to their broader availability and greater entrainment effects. These findings support using both waveform types in future studies on the long-term neuromodulatory effects of tTIS.