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Asymmetric bipedal locomotion--an adaptive response to incomplete spinal injury in the chick.

Abstract：

: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.

journal_name

Exp Brain Res

journal_title

Experimental brain research

authors

Muir GD,Katz SL,Gosline JM,Steeves JD

doi

10.1007/s002210050515

subject

Has Abstract

pub_date

1998-10-01 00:00:00

pages

275-82

issue

eissn

0014-4819

issn

1432-1106

journal_volume

122

pub_type

杂志文章

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Asymmetric bipedal locomotion--an adaptive response to incomplete spinal injury in the chick.