IEEE Trans Biomed Circuits Syst. 2023 Oct;17(5):1084-1096. doi: 10.1109/TBCAS.2023.3299750. Epub 2023 Nov 21.
The invasiveness of neuromodulation technologies that require surgical implantation (e.g., electrical and optical stimulation) may limit their clinical application. Thus, alternative technologies that offer similar benefits without surgery are of paramount importance in the field of neuromodulation. Low-intensity ultrasound is an emerging modality for neural stimulation as ultrasound can be focused in deep tissues with millimeter resolution. Transcranial focused ultrasound stimulation (tFUS) has already been demonstrated in a wide range of animals and even humans at different sonication frequencies (mostly in the sub-MHz range due to the presence of the skull). This article first provides some fundamental knowledge in ultrasound, and then reviews various examples of successful tFUS experiments in animals and humans using different stimulation patterns, as well as available tFUS technologies for generating, focusing, and steering ultrasound beams in neural tissues. In particular, phased array technologies for the ultrasound stimulation application are discussed with an emphasis on the design, fabrication, and integration of ultrasound transducer arrays as well as the design and development of phased array electronics with beamformer and high-voltage driver circuitry. The challenges in tFUS, such as its underlying mechanism, indirect auditory response, and skull aberration effects, are also discussed.
神经调节技术的侵袭性需要手术植入（例如，电和光刺激），这可能限制了其临床应用。因此，在神经调节领域，无需手术就能提供类似益处的替代技术至关重要。低强度超声是一种新兴的神经刺激方式，因为超声可以在具有毫米分辨率的深层组织中聚焦。经颅聚焦超声刺激（tFUS）已经在各种动物中得到了广泛的证明，甚至在不同的超声频率下在人类中也得到了证明（由于颅骨的存在，主要在亚兆赫兹范围内）。本文首先提供了一些关于超声的基础知识，然后回顾了在动物和人类中使用不同刺激模式的各种成功 tFUS 实验的例子，以及用于在神经组织中产生、聚焦和引导超声束的可用 tFUS 技术。特别是，讨论了用于超声刺激应用的相控阵技术，重点介绍了超声换能器阵列的设计、制造和集成，以及带有波束形成器和高压驱动器电路的相控阵电子设备的设计和开发。还讨论了 tFUS 的挑战，例如其潜在机制、间接听觉反应和颅骨像差效应。
