School of Social Development and Health Management, University of Health and Rehabilitation Sciences, Qingdao, China.
Krembil Research Institute, University Health Network, Toronto, Canada.
J Physiol. 2024 Jun;602(12):2931-2943. doi: 10.1113/JP285139. Epub 2024 May 2.
Theta-burst transcranial ultrasound stimulation (tbTUS) increases primary motor cortex (M1) excitability for at least 30 min. However, the remote effects of focal M1 tbTUS on the excitability of other cortical areas are unknown. Here, we examined the effects of left M1 tbTUS on right M1 excitability. An 80 s train of active or sham tbTUS was delivered to the left M1 in 20 healthy subjects. Before and after the tbTUS, we measured: (1) corticospinal excitability using motor-evoked potential (MEP) amplitudes from single-pulse transcranial magnetic stimulation (TMS) of left and right M1; (2) interhemispheric inhibition (IHI) from left to right M1 and from right to left M1 using a dual-site paired-pulse TMS paradigm; and (3) intracortical circuits of the right M1 with short-interval intracortical inhibition and intracortical facilitation (ICF) using paired-pulse TMS. Left M1 tbTUS decreased right M1 excitability as shown by decreased MEP amplitudes, increased right M1 ICF and decreased short-interval IHI from left to right hemisphere at interstimulus interval (ISI) of 10 ms but not long-interval IHI at interstimulus interval of 40 ms. The study showed that left M1 tbTUS can change the excitability of remote cortical areas with decreased right M1 excitability and interhemispheric inhibition. The remote effects of tbTUS should be considered when it is used in neuroscience research and as a potential neuromodulation treatment for brain disorders. KEY POINTS: Transcranial ultrasound stimulation (TUS) is a novel non-invasive brain stimulation technique for neuromodulation with the advantages of being able to achieve high spatial resolution and target deep brain structures. A repetitive TUS protocol, with an 80 s train of theta burst patterned TUS (tbTUS), has been shown to increase primary motor cortex (M1) excitability, as well as increase alpha and beta movement-related spectral power in distinct brain regions. In this study, we examined on the effects of the motor cortical tbTUS on the excitability of contralateral M1 measured with MEPs elicited by transcranial magnetic stimulation. We showed that left M1 tbTUS decreased right M1 excitability and left-to-right M1 interhemispheric inhibition, and increased intracortical facilitation of right M1. These results lead to better understand the effects of tbTUS and can help the development of tbTUS for the treatment of neurological and psychiatric disorders and in neuroscience research.
经颅超声刺激（TUS）能增加初级运动皮层（M1）的兴奋性，至少持续 30 分钟。然而，焦点 M1 的 TUS 对其他皮质区的远程影响尚不清楚。在此，我们检查了左 M1 的 TUS 对右 M1 兴奋性的影响。20 名健康受试者的左 M1 接受 80 秒的活动或假 TUS 训练。在 TUS 之前和之后，我们测量了：（1）使用左、右 M1 的单脉冲经颅磁刺激（TMS）测量皮质脊髓兴奋性（MEP 幅度）；（2）使用双位点成对 TMS 范式测量左到右 M1 和右到左 M1 的抑制性（IHI）；（3）使用短间隔内皮质内抑制和皮质内易化（ICF）的成对 TMS 测量右 M1 的皮质内回路。左 M1 的 TUS 降低了右 M1 的兴奋性，表现为 MEP 幅度降低、右 M1 的 ICF 增加以及短间隔内的 IHI 从左到右半球的 ISI 为 10ms，但 40ms 的长间隔内 IHI 不变。该研究表明，左 M1 的 TUS 可以改变远程皮质区的兴奋性，降低右 M1 的兴奋性和半球间抑制。在神经科学研究中以及作为脑疾病的潜在神经调节治疗方法，都应考虑 TUS 的远程效应。
经颅超声刺激（TUS）是一种用于神经调节的新型非侵入性脑刺激技术，具有能够实现高空间分辨率和靶向深部脑结构的优点。已显示重复 TUS 方案，即 80 秒的 theta 爆发模式 TUS（tbTUS）训练，可增加初级运动皮层（M1）的兴奋性，并增加不同脑区的 alpha 和 beta 运动相关频谱功率。在这项研究中，我们检查了运动皮质 tbTUS 对经颅磁刺激诱发的 MEP 测量的对侧 M1 兴奋性的影响。我们发现，左 M1 的 TUS 降低了右 M1 的兴奋性和左到右 M1 的半球间抑制，并且增加了右 M1 的皮质内易化。这些结果有助于更好地理解 tbTUS 的影响，并有助于开发 tbTUS 治疗神经和精神疾病以及神经科学研究。
