Summary

Spinal cord injury results in a wide range of behavioral changes including impaired motor and sensory function, autonomic dysfunction, spasticity, and depression. Currently, restoring lost motor function is the most actively studied and sought-after goal of spinal cord injury research. This research is rooted in the fact that although self-repair following spinal cord injury in adult mammals is very limited, there can be some recovery of motor function. This recovery is strongly dependent on the lesion size and location as well as on neural activity of denervated networks activated mainly through physical activity (i.e., rehabilitative training). Recovery of motor function is largely due to neuroplasticity, which includes adaptive changes in spared and injured neural circuitry. Neuroplasticity after spinal cord injury is extensive and includes mechanisms such as moderate axonal sprouting, the formation of new synaptic connections, network remapping, and changes to neuron cell properties. Neuroplasticity after spinal cord injury has been described at various physiological and anatomical levels of the central nervous system including the brain, brainstem, and spinal cord, both above and below injury sites. The growing number of mechanisms underlying postinjury plasticity indicate the vast complexity of injury-induced plasticity. This poses important opportunities to further enhance and harness plasticity in order to promote recovery. However, the diversity of neuroplasticity also creates challenges for research, which is frequently based on mechanistically driven approaches. The appreciation of the complexity of neuronal plasticity and the findings that recovery is based on a multitude and interlinked adaptations will be essential in developing meaningful new treatment avenues.