Altered Obstacle Negotiation after Low Thoracic Hemisection in the Cat
Altered Obstacle Negotiation after Low Thoracic Hemisection in the Cat
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DOI：
10.1089/neu.2010.1457
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发表时间：
2011-09-01
影响因子：
4.2
通讯作者：
Howland, Dena R.
中科院分区：
文献类型：
--
作者：
Doperalski, Adele E.;Tester, Nicole J.;Howland, Dena R.
人类发生侧向脊髓损伤（SCI）后，行走能力会得到显着恢复；然而，对于社区行走至关重要的运动适应性特征（包括障碍物谈判）仍然存在缺陷。正常的越过障碍是通过在摆动过程中增加屈曲来完成的。如果一个物体是意料之外的或脊髓上输入不存在，障碍协商可能涉及脊髓组织的绊倒纠正反应。部分 SCI 后这些自愿和反射成分如何受到影响尚未得到充分研究。这项研究首次描述了猫低位胸椎半截断后障碍物通过的恢复情况。猫在受伤前和受伤后都接受了穿越有障碍物的跑道的训练。评估集中在病变同侧的后肢。受伤前，猫通过在摆动过程中增加膝盖弯曲来有效地清除障碍。受伤后，障碍物间隙永久改变。 2周后，当基本的地上行走能力恢复时，后肢被拖过障碍物（接近90%）。令人惊讶的是，直到两周后才出现了错误的纠正反应。尽管在 4 至 8 周之间，接近障碍物时修改肢体轨迹的能力显着增加，但在接近障碍物时，肢体举升在大约 50% 的遭遇中仍然不足，甚至在 16 周时仍继续引起绊倒的纠正反应。在与完全清除的谈判过程中发现的受伤后前肢偏差，表明了一种潜在的训练策略，以增加成功清除的数量。因此，在完全切断一半脊髓后，改变同侧后肢轨迹的能力显示出显着恢复，并且到 16 周时可以在不接触的情况下有效清除障碍，类似于 50% 的时间。尽管这表明支持电路的可塑性，但不足以支持一致的间隙。即使在评估的最长期时间点（16 周），这种不一致也可能是导致 SCI 患者跌倒的一个促成因素。
Following a lateralized spinal cord injury (SCI) in humans, substantial walking recovery occurs; however, deficits persist in adaptive features of locomotion critical for community ambulation, including obstacle negotiation. Normal obstacle negotiation is accomplished by an increase in flexion during swing. If an object is unanticipated or supraspinal input is absent, obstacle negotiation may involve the spinally organized stumbling corrective response. How these voluntary and reflex components are affected following partial SCI is not well studied. This study is the first to characterize recovery of obstacle negotiation following low-thoracic spinal hemisection in the cat. Cats were trained pre- and post-injury to cross a runway with an obstacle. Assessments focused on the hindlimb ipsilateral to the lesion. Pre-injury, cats efficiently cleared an obstacle by increasing knee flexion during swing. Post-injury, obstacle clearance permanently changed. At 2 weeks, when basic overground walking ability been recovered, the hindlimb was dragged over the obstacle (similar to 90%). Surprisingly, the stumbling corrective response was not elicited until after 2 weeks. Despite a notable increase, between 4 and 8 weeks, in the ability to modify limb trajectory when approaching an obstacle, limb lift during obstacle approach was insufficient during similar to 50% of encounters and continued to evoke the stumbling corrective response even at 16 weeks. A post-injury lead limb bias identified during negotiations with complete clearance, suggests a potential training strategy to increase the number of successful clearances. Therefore, following complete severing of half of the spinal cord, the ability to modify ipsilateral hindlimb trajectory shows significant recovery and by 16 weeks permits effective clearing of an obstacle, without contact, similar to 50% of the time. Although this suggests plasticity of supporting circuitry, it is insufficient to support consistent clearance. This inconsistency, even at the most chronic time point assessed (16 weeks), is probably a contributing factor to falls reported for people with SCI.