Compensatory adaptation of parallel motor pathways promotes skilled forelimb recovery after spinal cord injury
Imran S. Sheikh,
Kathleen M. Keefe,
Noelle A. Sterling,
Ian P. Junker,
Chen Li,
Jie Chen,
Xiao-Ming Xu,
Lynn G. Kirby,
George M. Smith
Affiliations
Imran S. Sheikh
Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Center for Neural Rehabilitation and Repair, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
Kathleen M. Keefe
Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Center for Neural Rehabilitation and Repair, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
Noelle A. Sterling
Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Center for Neural Rehabilitation and Repair, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
Ian P. Junker
Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Center for Neural Rehabilitation and Repair, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
Chen Li
Department of Anatomy and Cell Biology, Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
Jie Chen
Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Center for Neural Rehabilitation and Repair, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
Xiao-Ming Xu
Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
Lynn G. Kirby
Department of Anatomy and Cell Biology, Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
George M. Smith
Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Center for Neural Rehabilitation and Repair, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; Corresponding author
Summary: Skilled forelimb patterning is regulated by the corticospinal tract (CST) with support from brainstem regions. When the CST is lesioned, there is a loss of forelimb function; however, if indirect pathways remain intact, rehabilitative training can facilitate recovery. Following spinal cord injury, rehabilitation is thought to enhance the reorganization and plasticity of spared supraspinal-propriospinal circuits, aiding functional recovery. This study focused on the roles of cervical propriospinal interneurons (PNs) and rubrospinal neurons (RNs) in the recovery of reaching and grasping behaviors in rats with bilateral lesions of the CST and dorsal columns at C5. The lesions resulted in a 50% decrease in pellet retrieval, which normalized over four weeks of training. Silencing PNs or RNs after recovery resulted in reduced retrieval success. Notably, silencing both pathways corresponded to greater functional loss, underscoring their parallel contributions to recovery, alongside evidence of CST fiber sprouting in the spinal cord and red nucleus.
