CORRECTIVE RESPONSES TO LOSS OF GROUND SUPPORT DURING WALKING .2. COMPARISON OF INTACT AND CHRONIC SPINAL CATS
CORRECTIVE RESPONSES TO LOSS OF GROUND SUPPORT DURING WALKING .2. COMPARISON OF INTACT AND CHRONIC SPINAL CATS
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DOI：
10.1152/jn.1994.71.2.611
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发表时间：
1994-02-01
影响因子：
2.5
通讯作者：
PEARSON, KG
中科院分区：
文献类型：
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作者：
HIEBERT, GW;GORASSINI, MA;PEARSON, KG
1.先前的研究描述了猫的一条后腿踩进洞里时的矫正反应。在这项研究中，我们通过比较完整的和慢性的脊髓猫的反应来检查这种行为在脊髓水平上的组织程度。2.成年猫被训练用后腿在跑步机上两足行走。训练结束后，通过录像机和双后腿肌肉的肌电记录，对步入跑步机腰带上的一个洞的反应进行了监测。在脊椎化几周后恢复了用后腿行走的能力的慢性脊椎猫身上，也记录了步入洞中的反应。3.两组动物的行为反应在两个方面有所不同。首先，完整的动物从洞中取出脚的屈曲运动开始的潜伏期较短(完整的动物为70-150毫秒，而脊柱动物为130-350毫秒)。第二，完整动物的屈曲运动较强。完整动物夸张的屈曲运动将爪子抬离洞口，并使跑步机腰带重新获得支撑。脊椎动物较弱的屈曲运动通常不足以将爪子从洞中完全抬起。4.完整动物和脊髓动物矫正反应过程中屈肌运动模式的差异与运动学上的差异相一致。首先，与正常动物相比，脊椎动物在脚进入洞后屈肌活动的开始时间推迟了大约100毫秒。其次，在完整的动物中，屈肌爆发的幅度相对于与踏步中摆动阶段相关的屈肌爆发的幅度增加，而在脊椎动物中，矫正反应中的屈肌爆发与摆动时发生的相似。5.在矫正反应和摆动过程中，完整动物和脊柱动物不同屈肌爆发的持续时间和时间相似，表明矫正反应涉及脊髓系统的激活，该系统通常产生摆动阶段的屈肌活动。我们得出的结论是，在完整动物的矫正反应中，该系统的激活是由脊柱上结构的输入促进的。6.在所有完好的动物和五只脊椎动物中的三只中，当脚进入洞时，后肢的支撑由对侧腿维持。这条腿的站立阶段延长，伸展明显增加。同侧小腿进入洞口后60ms左右，对侧小腿的伸肌活动量增加，这可能是因为额外的负荷。这些相似之处表明，在矫正反应期间，对侧腿维持支持的机制主要是在脊柱水平上组织的。
1. The preceding study described a corrective response in cats when one hind leg steps into a hole. In this investigation we examine the extent to which this behavior is organized at the spinal level by comparing the responses elicited in intact and chronic spinal cats. 2. Adult cats were trained to step bipedally with their hind legs on a treadmill. After training, the responses to stepping into a hole cut in the treadmill belt were monitored with a video recorder and by recording electromyograms from muscles in both hind legs. The responses to stepping into the hole were also recorded in chronic spinal cats that had recovered the ability to step with their hind legs a few weeks after spinalization. 3. The behavioral responses in the two groups of animals differed in two respects. First, the latency of the onset of the flexion movement to remove the foot from the hole was shorter in intact animals (70-150 ms in intact vs. 130-350 ms in spinal animals). Second, the flexion movement in the intact animals was stronger. The exaggerated flexion movement in intact animals lifted the paw well clear of the hole and allowed support to be regained on the treadmill belt. The weaker flexion movement in spinal animals was usually insufficient to lift the paw completely from the hole. 4. Differences in the motor patterns recorded from flexor muscles during the corrective response in intact and spinal animals correspond with the differences in the kinematics. First, the onset of flexor activity after the foot entered the hole was delayed by similar to 100 ms in spinal animals relative to intact animals. Second, in intact animals the magnitudes of flexor bursts were increased relative to the flexor bursts associated with the swing phase during stepping, whereas in spinal animals flexor bursts during the corrective response resembled those occurring during swing. 5. Similarities in the duration and the timing of bursts in different flexor muscles in intact and spinal animals during the corrective response and during swing indicated that the corrective response involves activation of the spinal system that normally produces swing phase flexor activity. We conclude that activation of this system is facilitated by input from supraspinal structures during the corrective response in intact animals. 6. In all intact animals and three of five spinal animals, support of the hindquarters when the foot entered the hole was maintained by the contralateral leg. The stance phase of this leg was prolonged and extension significantly increased. The magnitude of extensor activity in the contralateral leg increased similar to 60 ms after the ipsilateral leg entered the hole, presumably because of the additional loading. These similarities indicate that the mechanism by which the contralateral leg maintains support during the corrective response is organized primarily at the spinal level.