Swallowing is a complex sensorimotor process, which involves precise temporal coordination of the upper and lower lips, tongue, and pharyngeal and esophageal musculatures. This integrated process is controlled by neural interplay across cortical and subcortical networks. Although numerous functional brain imaging studies have suggested means to measure post-stroke pathological changes in the cortical control region of swallowing [1], identifying the precise functional localization of the motor area for swallowing has been challenging. This complexity is partly due to the extensive cortical network that executes the swallowing function [2]. Transcranial magnetic stimulation (TMS) has been proposed and used as a powerful tool for functional localization of swallowing function [3]. However, because pharyngeal motor cortex (M1) representation of the intrinsic swallowing muscles is overlaid by those of the tongue and jaw in the somatotopic organization of the motor cortex, localization of swallowing area is substantially more challenging than the standard motor mapping of the hand area. This makes the administering of the non-invasive stimulation to relevant swallowing areas as well as the recording of the elicited muscle responses particularly challenging. As a solution, we propose that surface electromyography (sEMG) recordings of lip orbicularis oris (OO) muscle activities elicited by a functional MRI (fMRI)-guided neuronavigated TMS (nTMS) techniquewould aid in the detection of the submental complex (SMC) muscles’ motor evoked potentials (MEPs) for localization of the SMC target in pharyngeal M1. We hypothesized that the lip OO target as a control target, could readily assist us in determining the SMC target (the candidate target). This hypothesis was made based on the previous studies in which the OO muscle was localized in the motor cortex during lip-pursing tasks using the rTMS procedure [4]. The OO muscle is an important orofacial muscle for initiating the swallowing function by creating and maintaining an adequate labial seal that prevents foods or liquids from leaking out of themouth duringmastication and the swallowing reflex. In addition, it plays critical roles in speech articulation and facial expressions. Therefore, mapping the lip motor area would not only provide an efficient means to precisely determine the SMC targeting intervention for rehabilitation of dysphagia, but also gives insight into therapeutic techniques for restoring lip functions in speech articulation and other lip muscle activities. Three healthy adult volunteer subjects (age 1⁄4 32.0 years; 1 female and 2 males) participated in this pilot study. Each subject participated in three study visits including the fMIR scan session, the TMS MEPs session, and the continuous theta burst transcranial

中文翻译：

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通过将非侵入性脑刺激与神经成像相结合来定位中枢吞咽功能

吞咽是一个复杂的感觉运动过程，涉及上下唇、舌头、咽部和食道肌肉组织的精确时间协调。这一整合过程由跨皮质和皮质下网络的神经相互作用控制。尽管许多功能性脑成像研究已经提出了测量吞咽皮质控制区域中风后病理变化的方法 [1]，但确定吞咽运动区域的精确功能定位一直具有挑战性。这种复杂性部分是由于执行吞咽功能的广泛皮质网络[2]。经颅磁刺激 (TMS) 已被提出并用作吞咽功能定位的有力工具 [3]。然而，因为内在吞咽肌肉的咽部运动皮层 (M1) 表示被运动皮层的体细胞组织中的舌头和下巴的表示所覆盖，因此吞咽区域的定位比手部区域的标准运动映射更具挑战性。这使得对相关吞咽区域进行非侵入性刺激以及记录引起的肌肉反应特别具有挑战性。作为一种解决方案，我们建议由功能性 MRI (fMRI) 引导的神经导航 TMS (nTMS) 技术引发的口轮匝肌 (OO) 肌肉活动的表面肌电图 (sEMG) 记录将有助于检测颏下复合体 (SMC) 肌肉' 运动诱发电位 (MEP) 用于定位咽部 M1 中的 SMC 目标。我们假设嘴唇 OO 目标作为控制目标，可以很容易地帮助我们确定 SMC 目标（候选目标）。这一假设是基于先前的研究提出的，在这些研究中，OO 肌肉在使用 rTMS 程序进行嘴唇撅起任务期间位于运动皮层中 [4]。OO 肌是重要的口面肌，它通过建立和维持足够的唇密封来启动吞咽功能，防止食物或液体在咀嚼和吞咽反射期间从口中漏出。此外，它在语音清晰度和面部表情中起着至关重要的作用。因此，绘制唇部运动区域图不仅可以提供一种有效的手段来精确确定 SMC 靶向干预以促进吞咽困难的康复，而且还深入了解了在语音清晰度和其他唇肌活动中恢复唇部功能的治疗技术。三名健康成年志愿者受试者（年龄 1⁄4 32.0 岁；1 名女性和 2 名男性）参加了这项试点研究。每个受试者都参加了三项研究访问，包括 fMIR 扫描会议、TMS MEP 会议和连续 theta 爆裂经颅