INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, Dijon, France.
Centre Hospitalier Le Vinatier, Université Claude Bernard Lyon 1, INSERM, CNRS, CRNL U1028 UMR5292, PsyR2 Team, Bron, France.
Eur J Neurosci. 2022 Dec;56(12):6187-6200. doi: 10.1111/ejn.15843. Epub 2022 Oct 18.
Motor imagery (MI) refers to the mental simulation of an action without overt movement. While numerous transcranial magnetic stimulation (TMS) studies provided evidence for a modulation of corticospinal excitability and intracortical inhibition during MI, the neural signature within the primary motor cortex is not clearly established. In the current study, we used directional TMS to probe the modulation of the excitability of early and late indirect waves (I-waves) generating pathways during MI. Corticospinal responses evoked by TMS with posterior-anterior (PA) and anterior-posterior (AP) current flow within the primary motor cortex evoke preferentially early and late I-waves, respectively. Seventeen participants were instructed to stay at rest or to imagine maximal isometric contractions of the right flexor carpi radialis. We demonstrated that the increase of corticospinal excitability during MI is greater with PA than AP orientation. By using paired-pulse stimulations, we confirmed that short-interval intracortical inhibition (SICI) increased during MI in comparison to rest with PA orientation, whereas we found that it decreased with AP orientation. Overall, these results indicate that the pathways recruited by PA and AP orientations that generate early and late I-waves are differentially modulated by MI.
运动想象（MI）是指在没有明显运动的情况下对动作进行心理模拟。虽然许多经颅磁刺激（TMS）研究为 MI 期间皮质脊髓兴奋性和皮质内抑制的调节提供了证据，但初级运动皮层内的神经特征尚未明确确定。在当前的研究中，我们使用定向 TMS 来探测 MI 期间早期和晚期间接波（I 波）生成途径的兴奋性调节。在初级运动皮层内，后前（PA）和前后（AP）电流流动的 TMS 诱发的皮质脊髓反应分别优先诱发早期和晚期 I 波。十七名参与者被指示保持休息或想象右手桡侧屈肌的最大等长收缩。我们证明，在 MI 期间，PA 方向的皮质脊髓兴奋性增加大于 AP 方向。通过使用成对脉冲刺激，我们证实与休息时相比，PA 方向的 MI 期间短程皮质内抑制（SICI）增加，而 AP 方向的 SICI 减少。总的来说，这些结果表明，产生早期和晚期 I 波的 PA 和 AP 方向所募集的途径受 MI 的差异调节。
