Motoneuron pool plasticity following spinal cord injury

项目总结 脊髓损伤后，脊髓运动神经元的特性发生改变，兴奋性和 汇聚在它们身上的抑制性突触通路。这种可塑性被认为是一种适应性 对受伤的反应，补偿下降动力的损失。或者，这样的更改可以是 适应不良，导致肌肉痉挛和受伤后拮抗肌群的共同激活。 脊髓的可塑性也提供了恢复功能和改善不良反应的治疗前景。 通过运动训练和反射调节等措施对脊髓损伤后的影响。在这 我们将确定脊髓不完整后运动神经元池组织的变化 运动训练对这些变化的影响，以及这些变化对运动神经元的影响 池功能。这些研究将使用不完全脊髓损伤的大鼠模型进行，在该模型中， 当动物处于深度麻醉状态时，脊髓损伤是由挫伤造成的。未受伤的老鼠将被 与不完全性脊髓损伤大鼠和不完全脊髓损伤大鼠比较 获得自愿运动锻炼的机会。这些组的大鼠将在1)强度方面进行比较 以及反射源和中枢(下行和固有脊髓)源在运动神经元池中的分布 突触兴奋；2)突触抑制反射来源的强度和分布；3)突触抑制 由这组运动神经元支配的肌肉纤维的收缩特性。每一项的组织 这些系统将根据运动神经元的内在属性和它们的 放电特性。不完全性脊髓损伤引起的改变对功能的影响 受伤后的运动治疗将通过模拟进行评估，使用一对拮抗剂的动态模型 运动神经元池-肌肉，其参数包括突触，运动神经元池和 在这些研究中观察到的肌肉组织。这个项目的总体目标是了解 一种常见脊髓损伤对运动神经元池组织和功能的影响 它控制的肌肉，并评估运动训练的益处和局限性。

Project summary Following spinal cord injury, alterations occur in the properties of spinal motoneurons and in the excitatory and inhibitory synaptic pathways that converge upon them. This plasticity has been considered an adaptive response to injury, compensating for loss of descending drive. Alternatively, such alterations may be maladaptive, contributing to muscle spasticity and coactivation of antagonist muscle groups following injury. The plasticity of the spinal cord also offers the promise of therapies to restore function and ameliorate adverse effects following spinal cord injury through such measures as locomotor training and reflex conditioning. In this project we will identify changes in the organization of motoneuron pools following incomplete spinal cord injuries, the effect of locomotor training on these changes, and the impact of these changes on motoneuron pool function. These studies will be conducted using a rat model of incomplete spinal cord injury in which a spinal cord injury is produced by contusion while the animal is deeply anesthetized. Uninjured rats will be compared to those with incomplete spinal cord injury and to rats with incomplete spinal cord injury given access to voluntary locomotor exercise. These groups of rats will be compared with respect to 1) the strength and distribution in a motoneuron pool of a reflex source and a central (descending and propriospinal) source of synaptic excitation; 2) the strength and distribution of a reflex source of synaptic inhibition; and 3) the contractile properties of muscle fibers innervated by this group of motoneurons. The organization of each of these systems will be characterized according to the intrinsic properties of the motoneurons and their discharge characteristics. The functional impact of changes produced by incomplete spinal cord injury and by exercise therapy following injury will be assessed by simulation, using a dynamic model of an antagonist pair of motoneuron pool-muscles whose parameters incorporate the changes in synaptic, motoneuron pool and muscle organization observed in these studies. The overall goal of this project is to gain an understanding of the effects of a common type of spinal cord injury on the organization and function of a motoneuron pool and the muscle it controls and to assess the benefits and limitations locomotor training.