De Leon R D, Hodgson J A, Roy R R, Edgerton V R
Department of Physiological Science, University of California, Los Angeles, California 90095, USA.
J Neurophysiol. 1998 Jul;80(1):83-91. doi: 10.1152/jn.1998.80.1.83.
Behavioral and physiological characteristics of standing were studied in nontrained spinal cats and in spinal cats that received daily stand training of the hindlimbs for 12 wk. Training consisted of assisting the cats to stand with full weight support either on both hindlimbs or on one hindlimb (30 min/day, 5 days/wk). Extensor muscle electromyographic (EMG) amplitude and extension at the knee and ankle joints during full weight bearing recovered to prespinal levels in both stand-trained and nontrained spinal cats. However, full weight bearing of the hindquarters was sustained for up to approximately 20 min in the spinal cats that received bilateral stand training compared with approximately 4 min in cats that were not trained to stand. Unilateral stand training selectively improved weight bearing on the trained limb based on ground reaction forces and extensor muscle EMG activity levels measured during bilateral standing. These results suggest that the capacity of the adult lumbar spinal cord to generate full weight-bearing standing can be improved by as much as fivefold by the repetitive activation of selected neural pathways in the spinal cord after supraspinal connectivity has been eliminated. Given that stepping is improved in response to step training, it appears that the recovery of standing provides another example of training-specific motor learning in the spinal cord, i.e., the spinal cord learns to perform hindlimb standing by practicing that specific task.
对未训练的脊髓猫以及接受了为期12周的后肢每日站立训练的脊髓猫的站立行为和生理特征进行了研究。训练包括协助猫在双后肢或单后肢完全负重的情况下站立（每天30分钟，每周5天）。在完全负重时，站立训练的和未训练的脊髓猫的伸肌肌电图（EMG）幅度以及膝关节和踝关节的伸展均恢复到脊髓损伤前的水平。然而，接受双侧站立训练的脊髓猫后躯能维持完全负重长达约20分钟，而未接受站立训练的猫约为4分钟。根据双侧站立时测量的地面反作用力和伸肌肌电图活动水平，单侧站立训练选择性地改善了训练肢体的负重能力。这些结果表明，在脊髓上连接被消除后，通过脊髓中选定神经通路的重复激活，成年腰脊髓产生完全负重站立的能力可提高多达五倍。鉴于对步幅训练的反应中步幅得到改善，看来站立恢复提供了脊髓中特定训练运动学习的另一个例子，即脊髓通过练习该特定任务学会进行后肢站立。
