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

该项目将开发一种低噪声经颅磁刺激(TMS)系统。TMS是一种技术 使用强而短暂的磁脉冲进行非侵入性脑刺激。TMS被广泛用作探测工具 具有脑功能，是FDA批准的治疗抑郁症的药物。然而，TMS的一个重要限制是 磁脉冲传输与高达140分贝的响亮的滴答声有关，这是由 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，它有效地减少了TMS的焦点，因为每次点击都会激活听觉皮质、脑干和其他 连通的区域，与磁脉冲同步。第二，重复的滴答声，两者都是本身 或者与TMS靶点的同步激活配对，可以诱导神经调节，从而干扰 与TMS目标的预期效果相混淆。第三，滴答声会影响盲人 TMS研究并有必要使用复制声音的虚假条件，但这可能会导致 还有不受欢迎的声音中介调制效果。最后，还有一些众所周知的安全问题，比如 听力损失和耳鸣的诱发，特别是在脆弱人群中，以及耐受性 考虑因素，因为TMS噪音可能会导致头痛，并导致某些患者不适。 为了满足这一需求，我们提出了一种静音TMS(QTMS)设备，它包含两个关键概念：第一， TMS脉冲声音的主要频率(通常为2-5 kHz)将被移至更高的频率， 高于人类听觉上限约20千赫。这将通过使 磁脉冲超短，并对其进行整形，使其基频在20 kHz以上。由于 神经反应的强度-持续时间特性，超短脉冲需要更高的幅度才能实现 神经刺激，但总脉冲能量实际上低于传统脉冲。第二，TMS 线圈将在电气和机械上重新设计，以产生超过阈值的电场脉冲，同时 将可听频率(&lt；20 kHz)发出的声音降至最低。这将需要线圈维持脉冲 更高的电压和电流，但持续时间比传统脉冲更短，同时最小化 在低于20千赫的频率下转换为声能并以声能的形式发射的电磁能量。这个 线圈的声学性能将通过一种新颖的分层线圈设计来实现。我们将设计 并在此基础上搭建了QTMS装置，目标是初步降低噪声40分贝 与传统设备相比。QTMS产生的神经和声音刺激将是 以台面测量和概念验证人体研究为特征。我们提供了来自一个 低幅度qTMS原型已经显示出使用超短脉冲将噪声降低19分贝，例如 以及一项人类研究的数据显示，在幅度调整的短暂和 脉搏很长。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.