Transcranial magnetic stimulation (TMS) studies showed that corticospinal excitability (CSE) is modulated during observation of object lifting, an effect termed ‘motor resonance’. Specifically, motor resonance is driven by movement features indicating object weight, such as object size or observed movement kinematics. We investigated in 16 humans (8 females) whether motor resonance is also modulated by an object's weight distribution. Participants were asked to lift an inverted T-shaped manipulandum with interchangeable center of mass after first observing an actor lift the same manipulandum. Participants and actor were instructed to minimize object roll and rely on constrained digit positioning during lifting. Constrained positioning was either collinear (i.e., fingertips on the same height) or noncollinear (i.e., fingertip on the heavy side higher than the one on the light side). The center of mass changed unpredictably before the actor's lifts and participants were explained that their weight distribution always matched the actor's one. Last, TMS was applied during both lift observation and planning of lift actions. Our results showed that CSE was similarly modulated during lift observation and planning: when participants observed or planned lifts in which the weight distribution was asymmetrically right-sided, CSE recorded from the thumb muscles was significantly increased compared to when the weight distribution was left-sided. During both lift observation and planning, this increase seemed to be primarily driven by the weight distribution and not specifically by the (observed) digit positioning or muscle contraction. In conclusion, our results indicate that complex intrinsic object properties such as weight distributions can modulate activation of the motor system during both observation and planning of lifting actions.

经颅磁刺激（TMS）研究表明，在观察物体抬起过程中，皮质脊髓兴奋性（CSE）受到调节，这种效应被称为“运动共振”。具体而言，运动共振由指示物体重量的运动特征驱动，例如物体大小或观察到的运动学。我们调查了16位人类（8位女性）是否通过物体的重量分布来调节运动共振。在首先观察到一个演员举起相同的Manipulandum之后，要求参与者举起重心可互换的倒T形Manilandandum。指示参与者和演员最小化对象滚动，并在举起过程中依靠受限的手指定位。约束定位是共线的（即指尖在同一高度）或非共线的（即，重指的指尖高于轻指的指尖）。在演员举重之前，重心发生了不可预测的变化，并向参与者解释说，他们的体重分布始终与演员的重心匹配。最后，在举升观测和举升行动计划中均应用了TMS。我们的结果表明，在举重观察和计划过程中，CSE受到类似的调节：当参与者观察或计划举重不对称于右侧的举重时，拇指肌肉记录的CSE与重量分布为左侧时相比明显增加。在升降机的观察和计划过程中，这种增加似乎主要是由体重分布驱动的，而不是（观察到的）手指位置或肌肉的收缩。综上所述，