Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:5084-5088. doi: 10.1109/EMBC48229.2022.9871603.
Temporal interference stimulation has been suggested as a method to reach deep targets during transcutaneous electrical stimulation. Despite its growing use in transcutaneous stimulation therapies, the mechanism of its operation is not fully understood. Recent efforts to fill that gap have focused on computational modelling, in vitro and in vivo experiments relying on physical observations - e.g., sensation or movement. This paper expands the current range of experimental methods by demonstrating in vivo extraneural recordings from the ulnar nerve of a pig while applying temporal interference stimulation at a location targeting a distal part of the nerve. The main aim of the experiment was to compare neural activation using sinusoidal stimulation (100 Hz, 2 kHz, 4 kHz) and temporal interference stimulation (2 kHz and 4 kHz). The recordings showed a significant increase in the magnitude of stimulation artefacts at higher frequencies. While those artefacts could be removed and provided an indication of the depth of modulation, they resulted in the saturation of the amplifiers, limiting the stimulation currents and amplifier gains used. The results of the 100 Hz sine wave stimulation showed clear neural activity correlated to the stimulation waveform. However, this was not observed with temporal interference stimulation. The results suggest that, despite its greater penetration, higher currents might be required to observe a neural response with temporal interference stimulation, and more complex artefact rejection techniques may be required to validate the method.
时程干扰刺激已被提议作为一种在经皮电刺激时到达深部靶标的方法。尽管它在经皮刺激治疗中的应用越来越广泛，但它的作用机制仍不完全清楚。最近为填补这一空白的努力集中在计算建模、依赖于物理观察的体外和体内实验上——例如感觉或运动。本文通过在猪的尺神经上施加靶向神经远端的时程干扰刺激，同时进行体内非神经记录，扩展了当前的实验方法范围。实验的主要目的是比较使用正弦波刺激（100 Hz、2 kHz、4 kHz）和时程干扰刺激（2 kHz 和 4 kHz）时的神经激活。记录显示，在更高频率下，刺激伪影的幅度显著增加。虽然这些伪影可以被去除，并提供调制深度的指示，但它们会导致放大器饱和，限制使用的刺激电流和放大器增益。100 Hz 正弦波刺激的结果显示出与刺激波形相关的清晰神经活动。然而，时程干扰刺激并没有观察到这种情况。结果表明，尽管时程干扰刺激的穿透深度更高，但可能需要更高的电流才能观察到神经反应，并且可能需要更复杂的伪影消除技术来验证该方法。
