Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, People's Republic of China.
Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
J Neural Eng. 2021 Mar 8;18(3). doi: 10.1088/1741-2552/abd2c9.
Transcranial temporally interfering stimulation (tTIS) is a noninvasive neuromodulation method, which has been reported to be able to affect the activity of small neuronal populations. To pinpoint smaller regions of the brain, a multi-channel tTIS strategy is proposed with larger numbers of electrodes and multiple sets of interfering fields.First, a computational model is adopted to prove the concept of multi-channel tTIS theoretically. Besides, animal experiments are implemented to activate motor cortex neurons in living mice and different frequencies are attempted. Finally, to better understand the envelope modulation properties of the two applied fields, tissue phantom measurement is conducted.The focality of six-channel (six electrode pairs) tTIS is increased by 46.7% and 70.2% respectively, compared with that of single-channel tTIS when maximal amplitude value drops by 3 dB and 6 dB in a numerical computation experiment. Furthermore, the focality of multi-channel tTIS is less sensitive to the electrode position. Confirmed with the myoelectricity signal, the movement frequencies of the contralateral forepaw are consistent with the corresponding difference frequencies. What is more, compared to single-channel (one electrode pair) tTIS with multi-channel (three electrode pairs) tTIS, the intensity of multi-channel tTIS stimulation is decreased by 28.5% on average in animal experiments. The c-fos-positive neurons of the target region are significantly higher than that of the non-target region. Results of the modulated envelope distribute around the whole region and its amplitude reaches a maximum at the interfering region.Both computational modeling and animal experiment validate the feasibility of the proposed multi-channel tTIS strategy and confirm that it can enhance focality and reduce scalp sensation.
经颅时变干扰刺激（tTIS）是一种非侵入性的神经调节方法，据报道，它能够影响小神经元群体的活动。为了精确定位大脑的较小区域，提出了一种多通道 tTIS 策略，该策略使用更多的电极和多组干扰场。首先，采用计算模型从理论上验证了多通道 tTIS 的概念。此外，还在活体小鼠中进行了动物实验，尝试了不同的频率。最后，为了更好地了解两个应用场的包络调制特性，进行了组织仿体测量。在数值计算实验中，当最大幅度值下降 3dB 和 6dB 时，六通道（六对电极）tTIS 的聚焦性分别比单通道 tTIS 提高了 46.7%和 70.2%。此外，多通道 tTIS 的聚焦性对电极位置的变化不敏感。通过肌电图信号证实，对侧前爪的运动频率与相应的差频一致。更重要的是，与单通道（一对电极）tTIS 相比，动物实验中多通道（三对电极）tTIS 的刺激强度平均降低了 28.5%。目标区域的 c-fos 阳性神经元明显高于非目标区域。调制包络的结果分布在整个区域，其幅度在干扰区域达到最大值。计算模型和动物实验都验证了所提出的多通道 tTIS 策略的可行性，并证实它可以增强聚焦性并减少头皮感觉。
