Structural and functional reorganization of propriospinal connections promotes functional recovery after spinal cord injury

Linard Filli; Martin E Schwab

doi:10.4103/1673-5374.155425

摘要：Axonal regeneration and ifber regrowth is limited in the adult central nervous system, but re-search over the last decades has revealed a high intrinsic capacity of brain and spinal cord circuits to adapt and reorganize after smaller injuries or denervation. Short-distance ifber growth and synaptic rewiring was found in cortex, brain stem and spinal cord and could be associated with restoration of sensorimotor functions that were impaired by the injury. Such processes of struc-tural plasticity were initially observed in the corticospinal system following spinal cord injury or stroke, but recent studies showed an equally high potential for structural and functional reorganization in reticulospinal, rubrospinal or propriospinal projections. Here we review the lesion-induced plastic changes in the propriospinal pathways, and we argue that they represent a key mechanism triggering sensorimotor recovery upon incomplete spinal cord injury. The for-mation or strengthening of spinal detour pathways bypassing supraspinal commands around the lesion site to the denervated spinal cord were identiifed as prominent neural substrate inducing substantial motor recovery in different species from mice to primates. Indications for the exis-tence of propriospinal bypasses were also found in humans after cortical stroke. It is mandatory for current research to dissect the biological mechanisms underlying spinal circuit remodeling and to investigate how these processes can be stimulated in an optimal way by therapeutic inter-ventions (e.g., ifber-growth enhancing interventions, rehabilitation). This knowledge will clear the way for the development of novel strategies targeting the remarkable plastic potential of pro-priospinal circuits to maximize functional recovery after spinal cord injury.