First close loop system that can adjust spinal cord signals in real time to enable synchronized stepping movement despite paralysis an other spinal...

Swiss scientists severed the spinal cords of a half-dozen rats and then implanted flexible electrodes into the lower part of their spinal cords. The animals were also given a type of drug known as a serotonin agonist, which Courtine says readies the spinal cord to communicate with the legs, an ability that’s depleted after an injury. With their weight supported by a harness, the rats were placed on a treadmill or on a runway with obstacles.

This spring, doctors and researchers from the University of Louisville and the University of California, Los Angeles, said four men who had been paralyzed for years were able to regain movement in their legs, hips, ankles, and toes, and even stand using an implanted device that stimulated their spinal cords, a technique called epidural stimulation.

Though the movements achieved were modest—and fall short of allowing the men to walk on their own—the technology let them exercise their legs, which seemed to restore some movement.

A limit to epidural stimulation so far is that the electrical pulses don’t produce complex, coӧrdinated movement. Also, in human tests, the stimulators are controlled manually. That’s where the system Courtine developed could come into play. By filming the rats as they walked, the Swiss team fed the images to software that quickly adjusted the pattern of stimulation to produce synchronized stepping movements.

Such a system could help a person walk rhythmically and maintain his balance.

“This is the first closed-loop control system that can really adjust leg movements in real time, despite paralysis,” Courtine says. Each of the rats walked at least a thousand successive steps and successfully navigated rodent-sized stairs.

Science Translational Medicine – Closed-loop neuromodulation of spinal sensorimotor circuits controls refined locomotion after complete spinal cord injury

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