Mechanical and Aerospace Engineering Department, UCLA, Los Angeles, CA, USA.
J Neurosci Methods. 2012 Apr 30;206(1):65-72. doi: 10.1016/j.jneumeth.2012.02.008. Epub 2012 Feb 14.
Toward improving the quantitative tools available for evaluation of locomotion after a spinal cord injury, we characterized selected biomechanical and physiological parameters that could be used to assess the level of recovery of locomotion after a mid-thoracic spinal cord lateral hemisection. Specifically we defined quantitative measures of muscle activation and coordination, body weight support, propulsive force, and pre-toe contact activation. Generation of this ensemble of recovery measures was based on kinematics, ground reaction forces, and EMG in rats from the hindlimb ipsilateral to the hemisection during quadrupedal running on a trackway. We derived muscle activation levels using inverse dynamics and static optimization applied to a model of the hindlimb musculoskeletal system. Rats exhibited a phased recovery pattern: progressive recovery of general muscle activity beginning within 2-3 days post-injury, followed by recovery of propulsive force and intralimb coordination of antagonistic muscles 12-13 days post-injury. Even at 12-13 days post-injury however, body weight support and the normal pre-paw contact EMG burst were significantly impaired. These data are consistent with a differential rate of recovery of general motor pool recruitment, and coordination among motor pools. The results demonstrate the discriminative potential of these physiologically based measures in quantifying the progressive recovery of gait performance after a lateral spinal cord hemisection.
为了改进评估脊髓损伤后运动功能的定量工具，我们对一些生物力学和生理学参数进行了特征描述，这些参数可以用于评估脊髓中部侧面半切后运动功能的恢复程度。具体来说，我们定义了肌肉激活和协调、体重支撑、推进力以及预足接触激活的定量测量方法。这些恢复措施的产生是基于半切后同侧后肢在轨道上四足跑动时的运动学、地面反作用力和 EMG。我们使用反向动力学和静态优化方法，对后肢肌肉骨骼系统的模型进行了分析，得出了肌肉激活水平。大鼠表现出分相恢复模式：损伤后 2-3 天开始出现一般肌肉活动的逐渐恢复，随后 12-13 天出现推进力和拮抗肌的内肢协调恢复。然而，即使在 12-13 天，体重支撑和正常的前足接触 EMG 爆发仍明显受损。这些数据与一般运动神经元募集和运动神经元协调的不同恢复率一致。结果表明，这些基于生理学的测量方法在定量评估脊髓中部侧面半切后步态恢复方面具有鉴别潜力。
