ACTIVITY DEPENDENT PLASTICITY AFTER HUMAN SPINAL CORD INJURY

人类脊髓损伤（SCI）后行走恢复的前景是黯淡的。康复的预后主要基于可检测到的自主腿部功能，这指导了脊髓损伤后行走的康复策略。这种方法是基于传统的人类运动神经控制层次模型的假设，该模型认为大脑是主要的控制者，脊髓是传导棘上信号和反射通路的管道。我们实验室和其他人最近的研究结果提出了一种运动神经控制的综合模型，将脊髓分配为运动的重要神经控制器，整合感觉和棘上信号以产生有效的运动输出。在这个提议中，我们通过理解感官和

The prospects for recovery of walking after human spinal cord injury (SCI) are dismal after a severe injury. The prognosis for recovery is primarily based on detectable voluntary leg function and this directs the rehabilitative strategy for walking after SCI. This approach is based on assumptions from the conventional hierarchal model of the neural control of locomotion in humans that designates the brain as the primary controller and the spinal cord as a conduit for supraspinal signals and reflex pathways. Recent results from our laboratory and others suggest an integrative model of the neural control of locomotion, allocating the spinal cord as an important neural controller of locomotion that integrates sensory and supraspinal signals to generate effective locomotor output. In this proposal we test this model by understanding sensory and supraspinal signal processing by the human spinal cord during the motor tasks of stepping and standing before and after each task specific training. We theorize that the neural circuitry of the human spinal cord is functionally organized to generate a particular efferent pattern when an expected set of kinematic and kinetic patterns are presented. We hypothesize that this neuralcircuitry can adapt to the repetitive presentation of a specific set of kinematic and kinetic patterns to modulate the efferent output in a predictable manner. We further hypothesize that after incomplete SCI both supraspinal and sensory signals can be integrated by the human spinal cord to generate a specific motor output that is related to repetitive stand or step training. We will study individuals following clinically complete SCI to understand the role of the human spinal cord in processing sensory signals. We will study individuals with clinically incomplete SCI to assess the integrative potential of supraspinal and sensory signals to generate functional output after repetitive stand or step training. We will examine the electromyographic activity, kinematics and kinetics of the lower limbs of these SCI subjects during bilateral and unilateral stepping and during functional tasks using body weight support on a treadmill after repetitive step or stand training. These studies will demonstrate aspects of use-dependent plasticity that are being studied in the animal models of this PPG. Identifying the specific sensory cues that facilitate motor output during stepping; and assessing whether repetitive task specific training can induce activity-dependent plasticity of spinal and supraspinal centers to result in functional improvements after spinal cord injury will have significant implications for new rehabilitative strategies for the recovery of walking after neurologic injury. Further, optimizing training strategies for functional recovery will also be extremely important in combination with promising neural regeneration approaches that are continuously emerging.