BACKGROUND Associative plasticity, the neurophysiological bases of Hebbian learning, has been implied in the formation of the association between sensory and motor representations of actions in the Mirror Neuron System; however, such inductor role still needs empirical support. OBJECTIVE/HYPOTHESIS We have assessed whether Paired Associative Stimulation (PAS), known to activate Hebbian associative plasticity, can induce the formation of atypical (absent in normal conditions), visuo-motor associations, reshaping motor resonance. METHODS Healthy participants underwent a novel PAS protocol (mirror-PAS, m-PAS), during which they were exposed to repeated pairings of transcranial magnetic stimulation (TMS) applied over the right primary motor cortex (M1), time-locked with the view of index-finger movements of the right (ipsilateral) hand. In a first experiment, the inter-stimulus interval (ISI) between visual-action stimuli and TMS pulses was varied. Before and after each m-PAS session, motor resonance was assessed by recording Motor Evoked Potentials induced by single-pulse TMS applied to the right M1, during the observation of both contralateral (left) and ipsilateral (right) index-finger movements. In the second experiment, the specificity of the m-PAS was assessed by presenting a visual stimulus depicting a non-biological movement. RESULTS Before m-PAS, the facilitation of corticospinal excitability occurred only during the view of contralateral (with respect to the TMS side) index-finger movements. The m-PAS induced new ipsilateral motor resonance responses, indexed by atypical facilitation of corticospinal excitability by the view of ipsilateral hand movements. This effect occurred only if the associative stimulation followed the chronometry of motor control (ISI of 25 ms) and if the visual stimulus of the m-PAS depicts a biological movement (human hand action). CONCLUSIONS The present findings provide the first empirical evidence that Hebbian learning induced by a PAS protocol shapes the visual-motor matching properties of the human Mirror Neuron System.

中文翻译：

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配对联想刺激驱动运动共振的出现

背景联想可塑性，赫布学习的神经生理学基础，已经暗示在镜像神经元系统中动作的感觉和运动表征之间的关联的形成中；然而，这种电感作用仍需要实证支持。目标/假设我们已经评估了已知激活 Hebbian 联想可塑性的成对联想刺激 (PAS) 是否可以诱导非典型（正常情况下不存在）视觉运动关联的形成，重塑运动共振。方法 健康的参与者接受了一种新的 PAS 协议（mirror-PAS、m-PAS），在此期间，他们暴露于施加在右侧初级运动皮层 (M1) 上的经颅磁刺激 (TMS) 重复配对，与视图时间锁定右手（同侧）手的食指运动。在第一个实验中，视觉动作刺激和 TMS 脉冲之间的刺激间隔 (ISI) 是变化的。在每次 m-PAS 会话之前和之后，在观察对侧（左）和同侧（右）食指运动期间，通过记录应用于右侧 M1 的单脉冲 TMS 诱发的运动诱发电位来评估运动共振。在第二个实验中，通过呈现描述非生物运动的视觉刺激来评估 m-PAS 的特异性。结果 在 m-PAS 之前，仅在对侧（相对于 TMS 侧）食指运动时才发生皮质脊髓兴奋性的促进。m-PAS 诱导了新的同侧运动共振反应，通过同侧手部运动的视角对皮质脊髓兴奋性的非典型促进进行索引。只有当联想刺激遵循运动控制的计时（ISI 为 25 毫秒）并且 m-PAS 的视觉刺激描绘了生物运动（人类手部动作）时，才会发生这种效果。结论目前的研究结果提供了第一个经验证据，证明由 PAS 协议诱导的赫布学习塑造了人类镜像神经元系统的视觉运动匹配特性。