Department of Physical Therapy, University of Florida, Gainesville, Florida;
J Neurophysiol. 2013 Sep;110(6):1415-25. doi: 10.1152/jn.00676.2012. Epub 2013 Jun 12.
A module is a functional unit of the nervous system that specifies functionally relevant patterns of muscle activation. In adults, four to five modules account for muscle activation during walking. Neurological injury alters modular control and is associated with walking impairments. The effect of neurological injury on modular control in children is unknown and may differ from adults due to their immature and developing nervous systems. We examined modular control of locomotor tasks in children with incomplete spinal cord injuries (ISCIs) and control children. Five controls (8.6 ± 2.7 yr of age) and five children with ISCIs (8.6 ± 3.7 yr of age performed treadmill walking, overground walking, pedaling, supine lower extremity flexion/extension, stair climbing, and crawling. Electromyograms (EMGs) were recorded in bilateral leg muscles. Nonnegative matrix factorization was applied, and the minimum number of modules required to achieve 90% of the "variance accounted for" (VAF) was calculated. On average, 3.5 modules explained muscle activation in the controls, whereas 2.4 modules were required in the children with ISCIs. To determine if control is similar across tasks, the module weightings identified from treadmill walking were used to reconstruct the EMGs from each of the other tasks. This resulted in VAF values exceeding 86% for each child and each locomotor task. Our results suggest that 1) modularity is constrained in children with ISCIs and 2) for each child, similar neural control mechanisms are used across locomotor tasks. These findings suggest that interventions that activate the neuromuscular system to enhance walking also may influence the control of other locomotor tasks.
模块是神经系统的一个功能单位,它指定了与肌肉激活相关的功能模式。在成年人中,有四个到五个模块负责行走时的肌肉激活。神经损伤改变了模块控制,并与行走障碍有关。神经损伤对儿童模块控制的影响尚不清楚,由于其不成熟和发育中的神经系统,可能与成年人不同。我们研究了不完全性脊髓损伤(ISCI)儿童和对照组儿童的运动任务的模块控制。五名对照组儿童(8.6±2.7 岁)和五名 ISCI 儿童(8.6±3.7 岁)进行了跑步机行走、地面行走、蹬踏、仰卧下肢屈伸、爬楼梯和爬行。双侧腿部肌肉记录肌电图(EMG)。应用非负矩阵分解,并计算达到 90%“方差解释”(VAF)所需的最小模块数。平均而言,3.5 个模块可以解释对照组的肌肉激活,而 ISCI 儿童则需要 2.4 个模块。为了确定控制是否在所有任务中都相似,从跑步机行走中确定的模块权重用于重建每个其他任务的 EMG。这导致每个孩子和每个运动任务的 VAF 值都超过 86%。我们的研究结果表明:1)ISCI 儿童的模块性受到限制;2)对于每个孩子,在运动任务中使用了相似的神经控制机制。这些发现表明,激活神经肌肉系统以增强行走的干预措施也可能影响其他运动任务的控制。