Opie George M, Sasaki Ryoki, Hand Brodie J, Semmler John G
Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide 5005, Australia.
Brain Sci. 2021 Jan 18;11(1):121. doi: 10.3390/brainsci11010121.
The late indirect (I)-waves recruited by transcranial magnetic stimulation (TMS) over primary motor cortex (M1) can be modulated using I-wave periodicity repetitive TMS (iTMS). The purpose of this study was to determine if the response to iTMS is influenced by different interstimulus intervals (ISIs) targeting late I-waves, and whether these responses were associated with individual variations in intracortical excitability. Seventeen young (27.2 ± 6.4 years, 12 females) healthy adults received iTMS at late I-wave intervals (4.0, 4.5, and 5.0 ms) in three separate sessions. Changes due to each intervention were examined with motor evoked potential (MEP) amplitudes and short-interval intracortical facilitation (SICF) using both posterior-anterior (PA) and anterior-posterior (AP) TMS current directions. Changes in MEP amplitude and SICF were influenced by iTMS ISI, with the greatest facilitation for ISIs at 4 and 5 ms with PA TMS, and 4 ms with AP TMS. Maximum SICF at baseline (irrespective of ISI) was associated with increased iTMS response, but only for PA stimulation. These results suggest that modifying iTMS parameters targeting late I-waves can influence M1 plasticity. They also suggest that maximum SICF may be a means by which responders to iTMS targeting the late I-waves could be identified.
经颅磁刺激（TMS）作用于初级运动皮层（M1）所引出的晚期间接（I）波，可通过I波周期性重复经颅磁刺激（iTMS）进行调制。本研究的目的是确定针对晚期I波的不同刺激间隔（ISI）是否会影响对iTMS的反应，以及这些反应是否与皮质内兴奋性的个体差异相关。17名年轻（27.2±6.4岁，12名女性）健康成年人在三个独立的时段接受了针对晚期I波间隔（4.0、4.5和5.0毫秒）的iTMS。使用前后（PA）和后前（AP）TMS电流方向，通过运动诱发电位（MEP）幅度和短间隔皮质内易化（SICF）来检查每次干预引起的变化。MEP幅度和SICF的变化受iTMS的ISI影响，PA TMS时，ISI为4和5毫秒时促进作用最大，AP TMS时，ISI为4毫秒时促进作用最大。基线时的最大SICF（与ISI无关）与iTMS反应增强相关，但仅适用于PA刺激。这些结果表明，改变针对晚期I波的iTMS参数可影响M1可塑性。它们还表明，最大SICF可能是识别针对晚期I波的iTMS反应者的一种方法。
