A previous study using traditional paired-pulse TMS methods (amplitude-tracking) has reported differences in resting motor threshold (RMT) and short-interval intracortical inhibition (SICI) between healthy subjects of Caucasian and Han Chinese backgrounds, probably due to differences in the skull shape. The amplitude-tracking method delivers stimuli with constant intensity, and causes substantial variabilities in MEP amplitudes. To overcome this variability, threshold tracking transcranial magnetic stimulation (TT-TMS) has been developed. The present study aimed to investigate whether racial differences in motor cortical function exist, using TT-TMS. A total of 83 healthy volunteers (30 Caucasians, 25 Han Chinese and 28 Japanese) were included in the present series. In TT-TMS and nerve conduction studies, electrodes were placed on the dominant limb, with measures recorded from the abductor pollicis brevis muscle. Stimulations were delivered with a circular coil, directly above primary motor cortex. There were no significant differences at all the SICI intervals between races. Similarly, there were no significant differences in other measures of excitability including mean RMT, intracortical facilitation, and cortical silent period. Contrary to traditional amplitude-tracking TMS, motor cortical excitability and thereby motor cortical function is minimally influenced by racial differences when measured by TT-TMS. Recent studies have disclosed that SICI measured by TT-TMS differentiates amyotrophic lateral sclerosis (ALS) from ALS mimic disorders, with high sensitivity and specificity, in Caucasians. This study suggested that TT-TMS can be applied for the ALS diagnosis in Asian patients, as well as Caucasians.

中文翻译：

---

通过阈值跟踪经颅磁刺激测量种族背景对运动皮层功能的影响

先前使用传统配对脉冲 TMS 方法（幅度跟踪）的研究报告了高加索和汉族背景的健康受试者之间的静息运动阈值 (RMT) 和短间隔皮质内抑制 (SICI) 的差异，这可能是由于在头骨形状。幅度跟踪方法提供具有恒定强度的刺激，并导致 MEP 幅度的显着变化。为了克服这种可变性，已经开发了阈值跟踪经颅磁刺激 (TT-TMS)。本研究旨在使用 TT-TMS 调查运动皮层功能是否存在种族差异。本系列共纳入 83 名健康志愿者（30 名白种人、25 名汉族和 28 名日本人）。在 TT-TMS 和神经传导研究中，将电极放置在优势肢体上，并从拇短展肌记录测量值。直接在初级运动皮层上方使用圆形线圈进行刺激。比赛之间的所有 SICI 间隔都没有显着差异。同样，在其他兴奋性指标（包括平均 RMT、皮质内促进和皮质静默期）方面也没有显着差异。与传统的振幅跟踪 TMS 不同，当通过 TT-TMS 测量时，运动皮层兴奋性和运动皮层功能受种族差异的影响最小。最近的研究表明，通过 TT-TMS 测量的 SICI 在高加索人中以高灵敏度和特异性区分肌萎缩侧索硬化症 (ALS) 和 ALS 模拟疾病。