Muir G D, Katz S L, Gosline J M, Steeves J D
Department of Zoology, University of British Columbia, Vancouver, Canada.
Exp Brain Res. 1998 Oct;122(3):275-82. doi: 10.1007/s002210050515.
The purpose of this study was to compare the asymmetric gait induced by unilateral spinal cord injury in chicks with asymmetric gaits of other bipeds and quadrupeds. After lateral hemisection of the left thoracic spinal cord, kinetic (ground reaction forces) and kinematic (distance and timing) data were recorded as chicks moved overground unrestrained. Ground reaction forces were analyzed to obtain the mechanical energy changes throughout the stride. Kinematic measurements were obtained over a range of speeds to determine the velocity-dependent characteristics of the gait. Hemisected chicks adopted an asymmetric hopping gait in which the animals hopped from the right leg (contralateral to the lesion) onto the left (ipsilateral) leg but then fell forward onto the right leg. Mechanical energy fluctuations throughout a single stride (i.e., two steps) approximated the oscillations that occur during a single walking step of control animals. When examined over a range of velocities, asymmetries in limb timing remained constant, but distance measurements such as step length became more symmetric as speed increased. The results show that, after spinal hemisection, adaptations of the remaining neural circuitry permitted the production of a locomotor pattern that, in addition to providing effective support and propulsion, incorporated some of the energy-conserving mechanisms of the normal walk. Adjustment of this novel locomotor pattern for different velocities further demonstrates the flexibility of locomotor circuitry. Comparisons with other studies shows that this gait shares some temporal and energetic features with asymmetric gaits of several bipedal species, including humans. In particular, hemisected chicks and some hemiplegic humans adopt an asymmetric gait in which maximum energy recovery occurs during the stance of the affected limb; these similarities probably relate to common mechanical constraints imposed on bipedal forms of terrestrial locomotion.
本研究的目的是比较雏鸡单侧脊髓损伤引起的不对称步态与其他两足动物和四足动物的不对称步态。在左侧胸段脊髓进行外侧半横切后，当雏鸡在无约束的地面上移动时，记录动力学（地面反作用力）和运动学（距离和时间）数据。分析地面反作用力以获得整个步幅的机械能变化。在一系列速度范围内进行运动学测量，以确定步态的速度依赖性特征。半横切的雏鸡采用不对称跳跃步态，动物从右腿（与损伤对侧）跳到左腿（同侧），但随后向前倒向右腿。单个步幅（即两步）中的机械能波动近似于对照动物单个步行步骤中发生的振荡。当在一系列速度下进行检查时，肢体时间的不对称性保持不变，但随着速度增加，诸如步长等距离测量变得更加对称。结果表明，脊髓半横切后，剩余神经回路的适应性允许产生一种运动模式，该模式除了提供有效的支撑和推进外，还融入了正常步行的一些节能机制。针对不同速度调整这种新的运动模式进一步证明了运动回路的灵活性。与其他研究的比较表明，这种步态与包括人类在内的几种两足动物的不对称步态具有一些时间和能量特征。特别是，半横切的雏鸡和一些偏瘫患者采用不对称步态，其中在患侧肢体站立期间发生最大能量恢复；这些相似性可能与对两足陆地运动形式施加的共同机械约束有关。
