Groupe de Recherche sur le Système Nerveux Central (FRSQ), Department of Physiology, Université de Montréal, Montreal, Quebec, Canada.
J Neurophysiol. 2012 Jul;108(1):124-34. doi: 10.1152/jn.00073.2012. Epub 2012 Apr 4.
While walking in a straight path, changes in speed result mainly from adjustments in the duration of the stance phase while the swing phase remains relatively invariant, a basic feature of the spinal central pattern generator (CPG). To produce a broad range of locomotor behaviors, the CPG has to integrate modulatory inputs from the brain and the periphery and alter these swing/stance characteristics. In the present work we raise the issue as to whether the CPG can adapt or reorganize in response to a chronic change of supraspinal inputs, as is the case after spinal cord injury (SCI). Kinematic data obtained from six adult cats walking at different treadmill speeds were collected to calculate the cycle and subphase duration at different stages after a first spinal hemisection at T(10) and after a subsequent complete SCI at T(13) respectively aimed at disconnecting unilaterally and then totally the spinal cord from its supraspinal inputs. The results show, first, that the neural control of locomotion is flexible and responsive to a partial or total loss of supraspinal inputs. Second, we demonstrate that a hemisection induces durable plastic changes within the spinal locomotor circuitry below the lesion. In addition, this study gives new insights into the organization of the spinal CPG for locomotion such that phases of the step cycle (swing, stance) can be independently regulated for adapting to speed and also that the CPGs controlling the left and right hindlimbs can, up to a point, be regulated independently.
在直线行走时，速度的变化主要是由于站立相持续时间的调整，而摆动相相对不变，这是脊髓中枢模式发生器（CPG）的基本特征。为了产生广泛的运动行为，CPG 必须整合来自大脑和外周的调制输入，并改变这些摆动/站立特征。在本工作中，我们提出了一个问题，即 CPG 是否能够适应或重组对脊髓上输入的慢性变化的反应，就像脊髓损伤（SCI）后一样。从以不同跑步机速度行走的六只成年猫中收集运动学数据，以计算第一次 T(10)脊髓半切和随后的 T(13)完全 SCI 后不同阶段的周期和亚相持续时间，旨在分别单侧和完全切断脊髓与其脊髓上输入的连接。结果表明，首先，运动的神经控制是灵活的，并对部分或完全失去脊髓上输入有反应。其次，我们证明半切在损伤以下的脊髓运动电路中引起持久的可塑性变化。此外，这项研究深入了解了用于运动的脊髓 CPG 的组织，使得步周期的相位（摆动、站立）可以独立调节以适应速度，并且控制左右后肢的 CPG 可以在一定程度上独立调节。
