Stehouwer D J, Van Hartesveldt C
Department of Psychology, and The Center for Neurobiological Sciences, University of Florida, Gainesville, FL 32611, USA.
Dev Psychobiol. 2000 Jan;36(1):1-8.
We studied the ability of L-DOPA (100 mg/kg, subcutaneous) to elicit air-stepping in decerebrate and sham-operated Sprague-Dawley rats from postnatal Day 5 through postnatal Day 20. The most common gait consisted of fore- and hindlimb alternation, but between 10 and 20 days of age, patterns of coordination resembling swimming, in which the forelimbs remained adducted, and galloping became more frequent in both decerebrate and sham-operated rats. Because episodes of galloping were rarely more than two or three step cycles in length, our analyses focused on episodes of stepping in which limbs within the girdles stepped in alternation and diagonal pairs of limbs moved in synchrony ("trot"). The rate of stepping of both decerebrate and sham-operated rats increased from about 2.9 steps/s at Day 5 to about 4 steps/s at Day 20. In both groups, this increase was found to result from a decrease in the duration of the retraction phase of the step cycle. Amplitudes of movement at the wrist, knee, and ankle increased with age in both decerebrate and sham-operated neonates, whereas those of the shoulder, elbow, and hip did not change in either group. The timing of movements at joints within each limb also changed similarly with age in sham-operated and decerebrate pups. During development, forelimb movement was increasingly led by the wrist, which was followed by the elbow and then finally by the shoulder. Hindlimb movements were increasingly led by the knee, followed by the ankle, and finally by the hip. At all ages, diagonal limbs moved in synchrony, and heterolateral limbs within each girdle moved in antiphase. However, the phase relationship between hindlimb and forelimb movements changed both in sham-operated rats and in decerebrate rats during ontogeny. On Day 5, movement of each hindlimb was phase-delayed relative to that of the diagonal forelimb whereas on Days 15 and 20, the hindlimb was phase-advanced. The parallel emergence of different gaits and the similarity of coordination during diagonal progression in sham-operated and decerebrate pups show that age-related changes in gait are mediated no more rostrally than the midbrain.
我们研究了左旋多巴（100毫克/千克，皮下注射）在出生后第5天至出生后第20天期间诱发去大脑和假手术的Sprague-Dawley大鼠空中踏步的能力。最常见的步态包括前肢和后肢交替，但在10至20日龄之间，类似游泳的协调模式（前肢保持内收）以及奔跑模式在去大脑和假手术大鼠中都变得更加频繁。由于奔跑发作很少超过两到三个步周期，我们的分析集中在腰带内肢体交替踏步且对角肢体同步移动（“小跑”）的踏步发作上。去大脑和假手术大鼠的踏步频率从第5天的约2.9步/秒增加到第20天的约4步/秒。在两组中，这种增加是由于步周期回缩阶段持续时间的减少。去大脑和假手术新生大鼠手腕、膝盖和脚踝处的运动幅度随年龄增加，而两组中肩部、肘部和髋部的运动幅度均未改变。假手术和去大脑幼崽中每个肢体关节的运动时间也随年龄发生类似变化。在发育过程中，前肢运动越来越多地由手腕引导，其次是肘部，最后是肩部。后肢运动越来越多地由膝盖引导，其次是脚踝，最后是髋部。在所有年龄段，对角肢体同步移动，每个腰带内的异侧肢体反相移动。然而，在个体发育过程中，假手术大鼠和去大脑大鼠的后肢与前肢运动之间的相位关系都发生了变化。在第5天，每个后肢的运动相对于对角前肢的运动相位延迟，而在第15天和第20天，后肢相位提前。假手术和去大脑幼崽中不同步态的平行出现以及对角行进过程中协调的相似性表明，与年龄相关的步态变化在中脑以上的部位介导作用不超过中脑。
