Identifying the Substrate for Successful Robot Rehabilitation in Adult Rats Spinalized as Neonates: The Role of the Trunk in Locomotor Recovery after Complete Low-Thoracic Transection.

摘要

Approximately 200,000 people live with spinal cord injury (SCI) worldwide, and more than 10,000 new cases are reported yearly. SCI patients suffer neurological deficits and severe functional loss below the level of injury, especially in cases where the cord is completely severed. After SCI, secondary injury processes worsen the damage, subsequently limiting the spinal cord's endogenous response to spontaneously repair and regenerate axons. This limits recovery of function. As a result, additional therapeutic interventions are often required to improve recovery. Unfortunately, there are no fully restorative therapies for SCI, but a lot of promising therapeutic techniques are currently being explored in animal models in labs across the globe.;One promising animal model for studying SCI recovery is a thoracic spinal cord spinalization in neonatal rats. This injury completely inhibits hindlimb stepping and locomotion. Using this model, spinalized neonates (NTX) manage to recover autonomous hindlimb weight supported (HWS) stepping as adults. Furthermore, intracortical microstimulation, cortical lesioning, and locomotor kinematic findings from the Giszter lab have identified cortical reorganization of trunk representation and trunk control as essential elements for NTX recovery.;NTX is the only reported successful autonomous recovery model known. Unfortunately, the mechanisms for this recovery have not yet been sufficiently investigated and are presently poorly understood. Consequently, in this thesis we explored the influence of trunk sensorimotor mechanisms on locomotor recovery after rat SCI. We investigated this trunk influence in two ways. First, we investigated trunk-locomotor interactions in adult intact rats by studying the effect of trunk muscle afferents on locomotion. Results from this study indicate that trunk muscle afferents modulate hindlimb extensor output during locomotion, which suggest the possibility of neuronal pathway(s) between trunk afferents and the spinal locomotor circuitry and HWS mechanisms. In the SCI rehabilitative tradition of using sensorimotor training to promote plasticity in hindlimb afferent reflex pathways, modifying trunk afferent reflexes in a similar context could also contribute to SCI locomotor recovery. Secondly, we studied the effect of trunk sensorimotor training on NTX recovery using a novel impedance training rehabilitation technique that interacts with the trunk Using our technique, some previously non-weight supporting rats achieve weight-support.