Behrendt Frank, de Lussanet Marc H E, Zentgraf Karen, Zschorlich Volker R
University Children's Hospital Basle, Basle, Switzerland.
Research Department, Reha Rheinfelden, Rheinfelden, Switzerland.
PLoS One. 2016 Jun 23;11(6):e0157811. doi: 10.1371/journal.pone.0157811. eCollection 2016.
Facilitation of the primary motor cortex (M1) during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer's motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS) to measure the corticospinal excitability of the m. erector spinae (ES) while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature.
仅仅在观察一个动作时，初级运动皮层（M1）的易化作用与所观察到的动作本身高度一致。这种一致性包括所执行动作的几个特征，如躯体定位和时间编码。使用伸手-抓握-提起范式的研究表明，观察者运动系统中特定肌肉的易化作用反映了在观察到的手部动作中施加的握力程度。在动作观察期间对提起物体的重量判断是一项简单任务，对于手部动作以及从地面提起箱子的情况都是如此。在这里，我们研究了M1中腰背部肌肉的皮层表征是否会像手部动作那样，由于观察全身提起动作而受到调制。我们使用经颅磁刺激（TMS）来测量竖脊肌（ES）的皮质脊髓兴奋性，同时让受试者视觉观察一个人从地面提起不同重量箱子的录制序列。与关于手部动作的结果一致，本研究揭示了尽管背部在M1中的表征相对较小，但对于主要涉及下背部肌肉组织的提起动作，皮质脊髓兴奋性仍存在差异调制。
