title: Trunk robot rehabilitation training with active stepping reorganizes and enriches trunk motor cortex representations in spinal transected rats.
abstract: Trunk motor control is crucial for postural stability and propulsion after low thoracic spinal cord injury (SCI) in animals and humans. Robotic rehabilitation aimed at trunk shows promise in SCI animal models and patients. However, little is known about the effect of SCI and robot rehabilitation of trunk on cortical motor representations. We previously showed reorganization of trunk motor cortex after adult SCI. Non-stepping training also exacerbated some SCI-driven plastic changes. Here we examine effects of robot rehabilitation that promotes recovery of hindlimb weight support functions on trunk motor cortex representations. Adult rats spinal transected as neonates (NTX rats) at the T9/10 level significantly improve function with our robot rehabilitation paradigm, whereas treadmill-only trained do not. We used intracortical microstimulation to map motor cortex in two NTX groups: (1) treadmill trained (control group); and (2) robot-assisted treadmill trained (improved function group). We found significant robot rehabilitation-driven changes in motor cortex: (1) caudal trunk motor areas expanded; (2) trunk coactivation at cortex sites increased; (3) richness of trunk cortex motor representations, as examined by cumulative entropy and mutual information for different trunk representations, increased; (4) trunk motor representations in the cortex moved toward more normal topography; and (5) trunk and forelimb motor representations that SCI-driven plasticity and compensations had caused to overlap were segregated. We conclude that effective robot rehabilitation training induces significant reorganization of trunk motor cortex and partially reverses some plastic changes that may be adaptive in non-stepping paraplegia after SCI.
authors.affiliation: School of Biomedical Engineering and Health Systems and.
authors.forename: Chintan S
authors.initials: CS
authors.lastname: Oza
authors.affiliation: School of Biomedical Engineering and Health Systems and Department of Neurobiology and Anatomy, Drexel University, Philadelphia, Pennsylvania 19129 simon.giszter@drexelmed.edu.
authors.forename: Simon F
authors.initials: SF
authors.lastname: Giszter
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001931:Brain Mapping / Q000379:methods; D005080:Exercise Test / Q000379:methods*; D005260:Female; D008124:Locomotion / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012371:Robotics / Q000379:methods*; D013119:Spinal Cord Injuries / Q000503:physiopathology / Q000534:rehabilitation*; D013904:Thoracic Vertebrae
keywords: cortex motor map; locomotion; muscle synergy; recovery of function; robot rehabilitation; spinal cord injury