Traumatic musculoskeletal injury (MSI) may involve changes in corticomotor structure and function but direct evidence is needed. To determine the corticomotor basis of MSI, we examined interactions among skeletomotor function, corticospinal excitability, corticomotor structure (cortical thickness and white matter microstructure), and intermittent theta burst stimulation (iTBS)-induced plasticity. Nine women with unilateral anterior cruciate ligament rupture (ACL) 3.2±1.1yr prior to the study and 11 matched controls (CON) completed an MRI session followed by an offline plasticity-probing protocol using a randomized, sham-controlled, double-blind, cross-over study design. iTBS was applied to the injured (ACL) or non-dominant (CON) motor cortex leg representation (M1_LEG) with plasticity assessed based on changes in skeletomotor function and corticospinal excitability compared to sham iTBS. The results showed persistent loss of function in the injured quadriceps, compensatory adaptations in the uninjured quadriceps and both hamstrings, and injury-specific increases in corticospinal excitability. Injury was associated with lateralized reductions in paracentral lobule thickness, greater centrality of non-leg corticomotor regions, and reduced (increased) primary somatosensory cortex leg area efficiency (segregation). Individual responses to iTBS were consistent with the principles of homeostatic metaplasticity; corresponded to injury-related differences in skeletomotor function, corticospinal excitability, and corticomotor structure; and suggested that corticomotor adaptations involve both hemispheres. Moreover, iTBS normalized skeletomotor function and corticospinal excitability in ACL. The results of this investigation directly confirm corticomotor involvement in chronic loss of function after traumatic MSI, emphasize the sensitivity of the corticomotor system to skeletomotor events and behaviors, and raise the possibility that brain-targeted therapies could improve recovery.

中文翻译：

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大脑结构的差异和 Theta Burst 刺激诱导的可塑性暗示皮质运动系统在肌肉骨骼损伤后功能丧失

外伤性肌肉骨骼损伤 (MSI) 可能涉及皮质运动结构和功能的变化，但需要直接证据。为了确定 MSI 的皮质运动基础，我们检查了骨骼运动功能、皮质脊髓兴奋性、皮质运动结构（皮质厚度和白质微结构）和间歇性 theta 脉冲刺激 (iTBS) 诱导的可塑性之间的相互作用。9 名在研究前 3.2±1.1 年患有单侧前交叉韧带断裂 (ACL) 的女性和 11 名匹配的对照 (CON) 完成了 MRI 会话，然后使用随机、假手术控制、双盲、交叉研究设计。iTBS 应用于受伤 (ACL) 或非优势 (CON) 运动皮层腿部表征 (M1 _LEG) 与假 iTBS 相比，根据骨骼运动功能和皮质脊髓兴奋性的变化评估可塑性。结果显示，受伤的股四头肌持续丧失功能，未受伤的股四头肌和双腿筋的补偿性适应，以及皮质脊髓兴奋性的损伤特异性增加。损伤与中央旁小叶厚度的侧向减少、非腿部皮质运动区的更大中心性以及降低（增加）初级躯体感觉皮层腿部面积效率（分离）有关。个体对 iTBS 的反应符合稳态化生性原则；对应于骨骼运动功能、皮质脊髓兴奋性和皮质运动结构的损伤相关差异；并建议皮质运动适应涉及两个半球。而且，iTBS 使 ACL 中的骨骼运动功能和皮质脊髓兴奋性正常化。这项调查的结果直接证实了皮质运动参与创伤性 MSI 后的慢性功能丧失，强调皮质运动系统对骨骼运动事件和行为的敏感性，并提高了大脑靶向治疗可以改善康复的可能性。