Quiet TMS: A Low-Acoustic-Noise Transcranial Magnetic Stimulation System

本计画将开发一套低杂讯的经颅磁刺激系统。TMS是一种技术 使用强而短的磁脉冲进行非侵入性脑刺激。TMS被广泛用作探测工具， 是FDA批准的治疗抑郁症的药物然而，TMS的一个重要局限性是， 磁脉冲输送与高达140 dB的响亮的咔哒声相关， 电磁力巨大的噪音严重阻碍了基础研究和临床应用。 TMS。首先，它有效地使TMS不那么集中，因为每次点击都会激活听觉皮层，脑干和其他神经元。 连接区域，与磁脉冲同步。第二，重复的咔嗒声， 或与TMS靶位点的同步激活配对，可以诱导神经调节， 与TMS目标的预期效果混淆。第三，咔嗒声噪声可能会损害 经颅磁刺激研究并需要使用假条件，复制声音，但可能会诱导 不希望的声音介导的调制效果。最后，存在已知的安全问题， 听力损失和耳鸣的诱导，尤其是在脆弱人群中，以及耐受性 由于TMS噪声可能会导致头痛，并导致某些患者不适，因此应考虑以下因素。 为了满足这一需求，我们提出了一种安静的TMS（qTMS）设备，它包含两个关键概念：首先， TMS脉冲声的主频率（通常为2-5 kHz）将被移动到更高的频率， 高于人类听力上限约20 kHz。这将通过使 磁脉冲超短时，并对其进行整形，使得其基频高于20 kHz。由于 由于超短脉冲具有神经反应的强度-持续时间特性，因此需要更高的幅度来实现 神经刺激，但总脉冲能量实际上低于常规脉冲。第二，TMS 线圈将在电气和机械上重新设计，以产生阈上电场脉冲， 最小化在可听频率（< 20 kHz）下发出的声音。这将需要线圈维持脉冲， 更高的电压和电流，但比传统脉冲的持续时间更短，同时最小化 电磁能被转换为频率低于20 kHz的声能并作为声能发射。的 线圈的增强的声学特性将通过新颖的分层线圈设计来实现。我们将设计 并基于这些概念构建qTMS设备，旨在将声学噪声初始降低40 dB 与传统设备相比。由qTMS产生的神经和声学刺激将被 其特征在于台式测量和概念验证人体研究。我们目前的试点数据从一个 低幅度qTMS原型已经证明了超短脉冲的噪声降低了19 dB， 以及一项人类研究的数据，显示幅度调整短暂与 长脉冲因此，qTMS技术可以实现更精确、有效、安全和可容忍的TMS。

This project will develop a low-noise transcranial magnetic stimulation (TMS) system. TMS is a technique for non-invasive brain stimulation using strong, brief magnetic pulses. TMS is widely used as a tool for probing brain function and is an FDA approved treatment for depression. A significant limitation of TMS, however, is that the magnetic pulse delivery is associated with a loud clicking sound as high as 140 dB resulting from electromagnetic forces. The loud noise significantly impedes both basic research and clinical applications of TMS. First, it effectively makes TMS less focal since every click activates auditory cortex, brainstem, and other connected regions, synchronously with the magnetic pulse. Second, the repetitive clicking sound, both by itself or paired with synchronous activation at the TMS target site, can induce neuromodulation that can interfere with and confound the intended effects at the TMS target. Third, the clicking noise can compromise blinding of TMS studies and necessitates the use of sham conditions that replicate the sound but that could induce undesirable sound-mediated modulation effects as well. Finally, there are known safety concerns regarding hearing loss and induction of tinnitus, especially in vulnerable populations, as well as tolerability considerations, since TMS noise may contribute to headache and cause discomfort in some patients. Addressing this need, we propose a quiet TMS (qTMS) device that incorporates two key concepts: First, the dominant frequency of the TMS pulse sound (typically 2–5 kHz) will be shifted to higher frequencies that are above the human hearing upper threshold of about 20 kHz. This will be accomplished by making the magnetic pulse ultrabrief, and shaping it so that its fundamental frequency is above 20 kHz. Due to the strength–duration properties of the neural response, ultrabrief pulses require higher amplitude to achieve neural stimulation, but the total pulse energy is actually lower than for conventional pulses. Second, the TMS coil will be redesigned electrically and mechanically to generate suprathreshold electric field pulses while minimizing the sound emitted at audible frequencies (< 20 kHz). This will require the coil to sustain pulses with higher voltage and current but of briefer duration than conventional pulses, while minimizing the electromagnetic energy that is converted to and emitted as acoustic energy at frequencies below 20 kHz. The enhanced acoustic properties of the coil will be accomplished with a novel, layered coil design. We will design and build a qTMS device based on these concepts, aiming at an initial reduction of the acoustic noise of 40 dB compared to a conventional device. The neural and acoustic stimulation produced by qTMS will be characterized in bench-top measurements and a proof-of-concept human study. We present pilot data from a low-amplitude qTMS prototype already demonstrating reduction of noise by 19 dB with ultrabrief pulses, as well as data from a human study showing comparable neural activation with amplitude-adjusted brief versus long pulses. Thus, qTMS technology could enable more precise, effective, safe, and tolerable TMS.