Training locomotor networks
Training locomotor networks
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DOI：
10.1016/j.brainresrev.2007.09.002
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发表时间：
2008-01-01
影响因子：
--
通讯作者：
Roy, Roland R.
中科院分区：
文献类型：
--
作者：
Edgerton, V. Reggie;Courtine, Gregoire;Roy, Roland R.
对于一个完整的成年脊髓大鼠，要恢复一些负重行走能力，似乎必须在重复的步循环中产生一系列相似但不相同的特定本体感觉输入。此外，这些循环必须包括腰骶脊髓节段固有的特定神经回路的激活。为了使这些感觉运动通路有效地产生步进，必须将脊髓回路调节到适当的兴奋性水平。这种水平的调节在完整的大鼠中由棘上输入维持，而不是脊柱大鼠。在一系列完整脊髓大鼠的实验中，我们已经表明，可以使用多种不同的方法来实现适当水平的脊髓回路兴奋性。例如，这种调节水平可以药理学上获得，通过硬膜外电刺激特定的腰骶脊髓节段，和/或通过使用依赖机制，如踏步或站立训练。关于这些治疗方法如何将脊髓回路“调谐”到一种“生理状态”，使其能够对本体感觉输入做出适当反应的证据将被提出。我们发现，每一种干预都可以使本体感觉输入实际控制广泛的细节，这些细节定义了跨越速度、负载和方向的动态。本文将描述一系列实验，说明脊髓损伤后对行走和站立的感觉控制，以及在兴奋性的关键窗口内调节脊髓回路的“生理状态”的必要性，以使这种控制得以体现。目前的研究结果不仅对我们理解行走运动模式是如何形成的，而且对设计康复干预措施以恢复脊髓损伤后人类腰骶回路功能具有重要意义。(c) 2007 Elsevier B.V.版权所有
For a complete adult spinal rat to regain some weight-bearing stepping capability, it appears that a sequence of specific proprioceptive inputs that are similar, but not identical, from step to step must be generated over repetitive step cycles. Furthermore, these cycles must include the activation of specific neural circuits that are intrinsic to the lumbosacral spinal cord segments. For these sensorimotor pathways to be effective in generating stepping, the spinal circuitry must be modulated to an appropriate excitability level. This level of modulation is sustained from supraspinal input in intact, but not spinal, rats. in a series of experiments with complete spinal rats, we have shown that an appropriate level of excitability of the spinal circuitry can be achieved using widely different means. For example, this modulation level can be acquired pharmacologically, via epidural electrical stimulation over specific lumbosacral spinal cord segments, and/or by use-dependent mechanisms such as step or stand training. Evidence as to how each of these treatments can "tune" the spinal circuitry to a "physiological state" that enables it to respond appropriately to proprioceptive input will be presented. We have found that each of these interventions can enable the proprioceptive input to actually control extensive details that define the dynamics of stepping over a range of speeds, loads, and directions. A series of experiments will be described that illustrate sensory control of stepping and standing after a spinal cord injury and the necessity for the "physiological state" of the spinal circuitry to be modulated within a critical window of excitability for this control to be manifested. The present findings have important consequences not only for our understanding of how the motor pattern for stepping is formed, but also for the design of rehabilitation intervention to restore lumbosacral circuit function in humans following a spinal cord injury. (c) 2007 Elsevier B.V. All rights reserved.