This study aimed to examine whether observing an expert's action swapped with an observer's face increases corticospinal excitability during combined action observation and motor imagery (AOMI). Twelve young males performed motor imagery of motor tasks with different difficulties while observing the actions of an expert performer and an expert performer with a swapped face. Motor tasks included bilateral wrist dorsiflexion (EASY) and unilateral two-ball rotating motions (DIFF). During the AOMI of EASY and DIFF, single-pulse transcranial magnetic stimulation was delivered to the left primary motor cortex, and motor-evoked potentials (MEPs) were obtained from the extensor carpi ulnaris and first dorsal interosseous muscles of the right upper limb, respectively. Visual analogue scale (VAS) assessed the subjective similarity of the expert performer with the swapped face in the EASY and DIFF to the participants themselves. The MEP amplitude in DIFF was larger in the observation of the expert performer with the swapped face than that of the expert performer (P = 0.012); however, the corresponding difference was not observed in EASY (P = 1.000). The relative change in the MEP amplitude from observing the action of the expert performer to that of the expert performer with the swapped face was positively correlated with VAS only in DIFF (r = 0.644, P = 0.024). These results indicate that observing the action of an expert performer with the observer's face enhances corticospinal excitability during AOMI, depending on the task difficulty and subjective similarity between the expert performer being observed and the observer.

中文翻译：

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在动作观察和运动想象相结合的过程中，观察专家的动作与观察者的面部交换会增加皮质脊髓的兴奋性

本研究旨在检验在联合动作观察和运动想象（AOMI）过程中，观察专家的动作与观察者的面部交换是否会增加皮质脊髓的兴奋性。十二名年轻男性在观察一名专家表演者和一名换脸专家表演者的动作的同时，对不同难度的运动任务进行了运动想象。运动任务包括双侧手腕背屈（EASY）和单侧双球旋转运动（DIFF）。在EASY和DIFF的AOMI过程中，向左侧初级运动皮层施加单脉冲经颅磁刺激，分别从尺侧腕伸肌和右上肢第一背侧骨间肌获得运动诱发电位（MEP） 。视觉模拟量表 (VAS) 评估了 EASY 和 DIFF 中交换面孔的专家表演者与参与者本身的主观相似性。交换脸部的专家表演者的观察中的 DIFF 中的 MEP 幅度大于表演专家的 MEP 幅度（P  = 0.012）；然而，在 EASY 中没有观察到相应的差异（P  = 1.000）。仅在 DIFF 中，从观察专家表演者的动作到观察交换脸部的专家表演者的动作时，MEP 幅度的相对变化与 VAS 呈正相关（r  = 0.644，P  = 0.024）。这些结果表明，用观察者的面部观察专家执行者的动作会增强 AOMI 期间的皮质脊髓兴奋性，具体取决于任务难度以及被观察的专家执行者与观察者之间的主观相似性。