LAUSR

Aim: To determine the effects of pulsed current transcutaneous spinal cord stimulation (TSCS) on both the spinal circuitry and the neuromotor response observed after a trunk force perturbation. Methods: A group of young healthy adults performed two experiments to study the effects of TSCS. In experiment I, the effect of TSCS on the spinal circuitry was assessed using the Hoffman-reflex (H-reflex) recruitment curve and recovery cycle. In Experiment II, the effect of TSCS on the response to trunk force perturbation was assessed with both stimulation on and off. The force perturbations were delivered by the robotic upright trunk support trainer (RobUST). Results: 30 Hz monophasic pulsed current TSCS induced spinal plasticity and increased spinal excitability. This TSCS protocol also increased muscle activation in response to specific pelvic force perturbations. These results suggest that TSCS can modulate the integration of voluntary descending commands and sensory signals and alter muscle activation during a postural task, even in neurologically intact subjects. We plan to use these results to develop training protocols to improve balance during standing in patients with spinal cord injury (SCI).