Ganzer Patrick Daniel, Meyers Eric Christopher, Sloan Andrew Michael, Maliakkal Reshma, Ruiz Andrea, Kilgard Michael Paul, Robert LeMoine Rennaker
The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080, United States.
The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080, United States.
Behav Brain Res. 2016 Jul 1;307:100-11. doi: 10.1016/j.bbr.2016.03.042. Epub 2016 Mar 28.
Spinal cord injury usually occurs at the level of the cervical spine and results in profound impairment of forelimb function. In this study, we recorded awake behaving intramuscular electromyography (EMG) from the biceps and triceps muscles of the impaired forelimb during volitional and reflexive forelimb movements before and after unilateral cervical spinal cord injury (cSCI) in rats. C5/C6 hemicontusion reduced volitional forelimb strength by more than 50% despite weekly rehabilitation for one month post-injury. Triceps EMG during volitional strength assessment was reduced by more than 60% following injury, indicating reduced descending drive. Biceps EMG during reflexive withdrawal from a thermal stimulus was increased by 500% following injury, indicating flexor withdrawal hyperreflexia. The reduction in volitional forelimb strength was significantly correlated with volitional and reflexive biceps EMG activity. Our results support the hypothesis that biceps hyperreflexia and descending volitional drive both significantly contribute to forelimb strength deficits after cSCI and provide new insight into dynamic muscular dysfunction after cSCI. The use of multiple automated quantitative measures of forelimb dysfunction in the rodent cSCI model will likely aid the search for effective regenerative, pharmacological, and neuroprosthetic treatments for spinal cord injury.
脊髓损伤通常发生在颈椎水平，导致前肢功能严重受损。在本研究中，我们记录了大鼠单侧颈脊髓损伤（cSCI）前后，在自主和反射性前肢运动过程中，受损前肢肱二头肌和肱三头肌的清醒行为肌电图（EMG）。C5/C6半横断损伤使自主前肢力量在损伤后一个月每周进行康复训练的情况下仍降低了50%以上。损伤后，自主力量评估期间肱三头肌EMG降低了60%以上，表明下行驱动减少。热刺激反射性退缩期间肱二头肌EMG在损伤后增加了500%，表明屈肌退缩反射亢进。自主前肢力量的降低与自主和反射性肱二头肌EMG活动显著相关。我们的结果支持以下假设，即肱二头肌反射亢进和下行自主驱动均显著导致cSCI后前肢力量缺陷，并为cSCI后动态肌肉功能障碍提供了新的见解。在啮齿动物cSCI模型中使用多种自动定量测量前肢功能障碍的方法可能有助于寻找脊髓损伤的有效再生、药理学和神经假体治疗方法。
