经颅磁声刺激与经颅超声刺激诱发肌电运动阈值的对比研究

Comparative study of transcranial magnetic stimulation and transcranial ultrasound stimulation on induced EMG motion threshold

目的:通过对经颅磁声刺激(transcranial magneto-acoustic stimulation,TMAS)与经颅超声刺激(transcranial ultrasound stimulation,TUS)诱发的小鼠肌电信号(electromyography,EMG)的采集与分析,对比小鼠的TMAS与TUS运动阈值,进而评估相对于TUS,TMAS对运动皮层的作用效果及潜在作用机制。方法:搭建针对小鼠的TUS与TMAS系统,设置不同超声强度的TUS与TMAS刺激参数,分别对TMAS与TUS诱发的小鼠EMG进行采集与分析,检测小鼠的TMAS与TUS运动阈值。结果:当刺激靶点处的空间峰值时间平均声强(Ispta)>144 mW/cm^2时,TUS与TMAS均能检测到小鼠的运动阈值,但TMAS能引起较稳定的运动反馈;当25 mW/cm^2<I_(spta)<144 mW/cm^2时,仅TMAS能检测到小鼠的运动阈值;当I_(spta)<25 mW/cm^2时,TUS与TMAS均未能检测到小鼠的运动阈值。结论:相对于TUS,TMAS能在更低的超声强度(Ispta)作用下兴奋小鼠的运动皮层,诱发小鼠EMG并获得运动阈值。TMAS较TUS具有更有效的运动皮层调控能力。TMAS实际上是一种结合了磁声耦合电场与声场的复合刺激,同步的声场与磁声耦合电场形成了对小鼠脑运动皮层的协同调控。

Objective To compare the cortical motion thresholds respectively by transcranial magneto-acoustic stimulation(TMAS)and transcranial ultrasound stimulation(TUS)and evaluate the efficacy and potential mechanism of TMAS on motor cortex when compared with TUS by collecting and analyzing the TMAS-and TUS-induced electromyography(EMG)signals.Methods A set of TUS-TMAS system for mice was set up.The stimulation parameters with different ultrasound intensities in TUS and TMAS were designed.To detect the TMAS and TUS motion thresholds of mice,the EMG induced by TMAS and TUS were collected and analyzed.Results When the spatial-peak temporal-average intensity(Ispta)of the target was more than 144 mW/cm2,both TUS and TMAS could acquire the motion threshold of mice,while TMAS caused more stable motion feedback;in case of 25 mW/cm2<Ispta<144 mW/cm2,only TMAS could acquire the threshold of motion in mice;in case of Ispta<25 mW/cm2,neither TUS nor TMAS could acquire the threshold of motion in mice.Conclusion Compared with TUS,TMAS can excite the motor cortex of mice under the action of lower ultrasound intensity(Ispta),and acquire the motion threshold of mice.The results show that TMAS is more effective for motivating motor cortex than TUS on regulation ability.TMAS is supposed to function as a dual-mode stimulation combining the electric field of the magneto-acoustic effect and the mechanical force of TUS.The spatially and temporally synchronousacoustic field and the magneto-acoustic coupling electric field induce a coordinated modulation in motor cortex of mice.