感觉输入干扰对咬肌运动皮质可塑性的影响

Influence of sensory input interference on motor cortex plasticity of masseter muscle

目的:本研究评估了感觉输入干扰对健康受试者牙齿咬合力精确控制训练(tooth-clenching task,TCT)后初级运动皮质(MI)咬肌控制区兴奋性变化的影响。方法:本试验纳入12名健康受试者进行了为期两期的垂直向研究,第一期:直接进行1小时TCT。第二期:切牙局部浸润麻醉下进行1小时TCT。应用导航经颅磁刺激(nTMS)对两期试验在基线和训练后两个时间点测量并记录受试者MI咬肌控制区及MI第一指间骨肌(FDI)控制区的特征。利用配对T检验分别对两期试验训练前后牙齿咬合力精确控制度进行比较,并对MI咬肌控制区及MI第一指间骨肌(FDI)控制区的运动诱发电位(MEP)平均振幅、运动阈值、地图面积进行比较。结果:在第一期试验中训练后与训练前相比咬肌皮质控制区MEPs平均振幅显著增加、牙齿咬合力控制精度显著增加(P<0.05),而第二期试验中训练前后MEPs平均振幅差异无统计学意义、牙齿咬合力控制精度无显著差异(P>0.05)。结论:1小时TCT可引发咬肌控制区域皮质兴奋性发生改变,切牙区局部浸润麻醉所引发的感觉输入干扰,钝化了TCT对大脑运动皮质咬肌控制区兴奋性的影响。

Objective:This study evaluated the effect of sensory input interference on excitatory changes in the primary motor cortex(MI)control area of the masseter muscle after tooth-clenching task(TCT)in healthy subjects.Methods:The study included 12 healthy subjects for a two-phase trial,Phase 1:Direct 1-hour TCT,Phase II:1-hour TCT was performed under local infiltration anesthesia of the incisor.Navigational transcranial magnetic stimulation(n TMS)was used to measure and record the characteristics of MI masseter control area and MI first interphalangeal musculi(FDI)control area at baseline and at two time points after training.Paired T test was used to compare the precision control degree of tooth bite force before and after the two phases of experimental training,and the mean amplitude of motor evoked potential(MEP),motion threshold and map area of MI masseter control area and MI first interphalanx(FDI)control area were compared.Results:In the first phase of the experiment,the mean amplitude of MEPs in the control area of the masseter cortex was significantly increased after training compared with that before training(P<0.05),while in the second phase of the experiment,the mean amplitude of MEPs before and after training was not statistically different,and the control precision of tooth bite force was also not significantly different(P>0.05).Conclusion:1-hour TCT can induce changes in the excitability of the masseter control area of the cortex.Sensory input interference caused by local infiltration anesthesia in the incisor area can dull the effects of TCT on the excitability of the masseter control area of the motor cortex of the brain.