Adaptations to robotic resistance during treadmill training in SCI rats

California State University Los Angeles, Los Angeles CA

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Abstract

Abstract Gait training therapies improve the recovery of locomotor function following spinal cord injury. The time, cost and energy involved in gait training therapy limit its effectiveness and for many people with spinal cord injury, these factors limit access to therapy. Recent findings suggest that applying forces that resist limb movements has a temporary, beneficial effect on walking in people with spinal cord injury. These findings raise the possibility that integrating resistive forces into a gait training therapy will enhance the effectiveness of the therapy. We propose to study the effects of resistive force training in a rodent model of spinal cord injury. Our hypothesis is that applying resistive forces during treadmill training will induce changes within the nervous system that promote long-term locomotor recovery. Three specific aims are proposed. First, we will test the effects of three types of resistive forces that target specific movements and determine which force corrects movement trajectory and hindlimb muscle EMG activity. A robotic device will be used to apply the forces to the rat hindlimbs while they are trained to perform weight-supported, treadmill stepping. Second, we will determine if the effects of resistive force training on the treadmill result in improved quadrupedal, overground locomotion. Third, we will determine if resistive force training induces synaptic plasticity in the spinal cord. Specifically, synapses onto hindlimb muscle motor neurons will be examined. The proposed studies will utilize a number of different approaches (i.e. robotic-assisted gait training, kinematic and behavioral analyses, electrophysiology, and immunohistochemistry). The PI's laboratory at Cal State LA has been studying robotic-applied forces in the rodent models of spinal cord injury and thus has all the expertise necessary to perform the proposed work. If successful, the results will have important implications for gait training therapies that are currently used for spinal cord injured people. Specifically, we will know if applying resistive forces during training will have a long- term effect on recovery and we will also gain insight into how resistive forces should be used for maximal therapeutic effect.