Locomotion Control by Lumbar Spinal Cord Stimulation

描述（申请人提供）：腰部以上的脊髓损伤（SCI）后，由于失去来自大脑的下行指令，下肢会瘫痪。然而，脊髓损伤后，腰椎神经间网络仍能维持运动功能，如气踏。慢性脊髓损伤猫也可以在训练后在跑步机上站立或行走一小段时间。不完全性脊髓损伤患者可以在广泛的跑步机训练后恢复地面活动能力。这些结果表明，脊髓损伤后，腰椎神经间网络在适当激活的情况下可以进行运动。因此，我们在本项目中建议电激活猫的腰椎神经元间运动网络，以恢复脊髓损伤后的行走功能。先前的研究表明，腰椎神经元间运动网络可以通过几个电极激活，引发复杂的、协调的、多关节的运动。当使用传统的周围神经肌肉刺激时，这种运动需要许多电极。脊髓刺激的其他优点包括：(1)与肌肉内电极相比，椎管中的电极运动相对较小，因此破损较少；(2).腰椎神经元间运动网络能按生理招募顺序激活肌肉，更能抵抗疲劳。肌肉疲劳是周围神经肌肉刺激的主要问题。在这个项目中，我们将确定有效的刺激位置，并制定控制策略，以恢复脊髓损伤猫的行走功能，使用脊髓外电刺激结合脊髓内刺激。与脊髓内电极相比，脊髓外电极对脊髓的损伤较小，但在激活腰椎深处的神经成分方面，脊髓内电极比脊髓外电极更有效。这项在猫身上的研究的成功将提示如何进行人体研究。该项目的长期目标是开发一种基于腰椎脊髓刺激的新型运动神经假体。本研究不仅将提高我们对腰椎运动控制的认识，也将使脊髓损伤患者受益。

DESCRIPTION (provided by applicant): After spinal cord injury (SCI) above the lumbar level, the lower limbs will be paralyzed due to the loss of descending commands from the brain. However, after SCI the interneuronal network in lumbar spinal cord can still sustain locomotor function such as air-stepping. Chronic SCI cats can also stand or walk for a short time on a treadmill after training. Patients with incomplete SCI can regain over ground mobility after extensive treadmill training. All of these observations indicate that the interneuronal network in lumbar spinal cord can carry out locomotion after SCI, if it can be activated properly. Therefore, we propose in this project to electrically activate the lumbar interneuronal locomotor network in cats to restore walking function after SCI. Previous studies have shown that the lumbar interneuronal locomotor network can be activated with only a few electrodes to elicit complex, coordinated, multi-joint movements. Such movements require many electrodes when traditional peripheral neuromuscular stimulation is used: Other advantages of spinal cord stimulation include: (1). electrodes in spinal canal experience relatively small movements, and thus exhibit less breakage, than the intramuscular electrodes; (2). the lumbar interneuronal locomotor network can activate muscles in a physiological recruitment order, which is more resistant to fatigue. Muscle fatigue is a major problem in the peripheral neuromuscular stimulation. In this project we will identify the effective stimulation locations and develop the control strategy to restore walking function in SCI cats, using extra- spinal electrical stimulation of the lumbar spinal cord in combination with intra-spinal stimulation. The extra- spinal electrode is less invasive to the spinal cord than the intra-spinal electrode, but the intra-spinal electrode is more effective than the extra-spinal electrode to activate the neural component deep in the lumbar spinal cord. The success of this study in cat will suggest how human studies could be pursued. The long-term goal of this project is to develop a new neuroprosthesis for locomotion based on lumbar spinal cord stimulation. The proposed studies will not only improve our understanding of locomotion control in lumbar spinal cord but also benefit SCI patients.