Department of Brain Sciences, Imperial College London, London, United Kingdom; UK Dementia Research Institute, Imperial College London, United Kingdom.
Institut de Neurosciences des Systèmes (INS), INSERM, UMR_1106, Aix-Marseille Université, Marseille, France; Department of Neurosurgery, Emory University, Atlanta, GA, USA.
Brain Stimul. 2024 Jan-Feb;17(1):92-103. doi: 10.1016/j.brs.2023.12.010. Epub 2023 Dec 23.
Electrical stimulation involving temporal interference of two different kHz frequency sinusoidal electric fields (temporal interference (TI)) enables non-invasive deep brain stimulation, by creating an electric field that is amplitude modulated at the slow difference frequency (within the neural range), at the target brain region.
Here, we investigate temporal interference neural stimulation using square, rather than sinusoidal, electric fields that create an electric field that is pulse-width, but not amplitude, modulated at the difference frequency (pulse-width modulated temporal interference, (PWM-TI)).
METHODS/RESULTS: We show, using ex-vivo single-cell recordings and in-vivo calcium imaging, that PWM-TI effectively stimulates neural activity at the difference frequency at a similar efficiency to traditional TI. We then demonstrate, using computational modelling, that the PWM stimulation waveform induces amplitude-modulated membrane potential depolarization due to the membrane's intrinsic low-pass filtering property.
PWM-TI can effectively drive neural activity at the difference frequency. The PWM-TI mechanism involves converting an envelope amplitude-fixed PWM field to an amplitude-modulated membrane potential via the low-pass filtering of the passive neural membrane. Unveiling the biophysics underpinning the neural response to complex electric fields may facilitate the development of new brain stimulation strategies with improved precision and efficiency.
通过在目标脑区产生幅度调制在慢差频（神经范围内）的电场，实现两种不同 kHz 频率正弦电场的时间干扰（TI），从而实现非侵入性的大脑深部刺激。
本研究采用方波而非正弦波的电场进行时间干扰神经刺激，创建一种在差频处脉冲宽度而非幅度调制的电场（脉宽调制时间干扰（PWM-TI））。
方法/结果：我们通过离体单细胞记录和体内钙成像显示，PWM-TI 以与传统 TI 相似的效率有效地刺激差频处的神经活动。然后，我们通过计算模型证明，由于细胞膜的固有低通滤波特性，PWM 刺激波形会引起幅度调制的膜电位去极化。
PWM-TI 可以有效地在差频处驱动神经活动。PWM-TI 机制涉及通过被动神经膜的低通滤波，将包络幅度固定的 PWM 场转换为幅度调制的膜电位。揭示复杂电场引起神经反应的生物物理机制，可能有助于开发具有更高精度和效率的新型脑刺激策略。
