International Encyclopedia of Rehabilitation

After spinal cord injury (SCI) of the cat or rat neuronal circuits below the level of lesion exhibit plasticity that can be exploited by specific training paradigms. In individuals with complete or incomplete SCI, human spinal locomotor centers can be activated by providing an appropriate afferent input. This includes to facilitate and assist stepping movements of the legs and to provide body weight support (BWS) of SCI subjects standing on a moving treadmill. Individuals with incomplete SCI benefit from such locomotor training such that they improve the ability to walk over ground. Loadand hipjoint-related afferent input seems to be of crucial importance for both the generation of a locomotor pattern and the effectiveness of the training. It appears to be a critical combination of afferent signals that is needed to generate and improve a locomotor pattern after a SCI. Several years of driven gait orthoses can provide a standardized locomotor training. In the future, if regeneration approaches can successfully be applied in human SCI, even individuals with complete SCI may recover walking ability with locomotor training. However, recent studies also indicate that in individuals with a severe SCI, spinal neuronal circuits undergo a degradation of their function 1 year after injury. Generation of locomotor activity Neuronal circuits (networks of interneurons) within the spinal cord that interact with specific sensory information under supraspinal control are responsible for locomotion in non-primate mammals (Barbeau and Rossignol 1987). These spinal neuronal circuits are defined as central pattern generators (CPGs) and were identified with experiments that demonstrated self-sustained patterns of locomotor-like neuronal activity generated independently of supraspinal and afferent input (Barbeau and Rossignol 1994, Pearson 2000). The understanding of the basis principles of CPG function is based on research in vertebrates and invertebrates. This research has shown that a significant level of control of locomotion is mediated at the level of the spinal cord. In fact, spinally transected animals can relearn or reexpress hindlimb stepping in the absence of input from the brain (Barbeau and Rossignol 1987, Barbeau and Rossignol 1994, Pearson 2000). There is convincing evidence in spinal animals that use-dependent plasticity of spinal neuronal circuits modifies the sensory-motor function of lumbosacral spinal cord. Regular locomotor training after complete spinal cord transection in adult cats improved the recovery of hindlimb function. Whether these neuronal properties such as the CPG also exist in humans is of crucial importance for the recovery of standing and walking