Paraplegic rats that couldn’t move their legs voluntarily can now walk and even run again after undergoing tests at UCLA. Neuroscientists used a combination of drugs, electrical stimulation and regular exercise to help rats with complete spinal cord injuries regain movement, spurring hopes that similar treatments could help humans with paralysis.

The findings, published in the online edition of Nature Neuroscience, suggest that the regeneration of severed nerve fibers isn’t necessarily required for paralyzed rats to learn to walk again.

There’s a slight catch, however: the rats aren’t exactly walking of their own volition. The paralyzed rats were set on a moving treadmill belt and given drugs that act on the neurotransmitter seratonin. Scientists applied low levels of electrical currents to the spinal cord below the point of injury to stimulate movement.

"The spinal cord contains nerve circuits that can generate rhythmic activity without input from the brain to drive the hind leg muscles in a way that resembles walking called 'stepping'," said principal investigator Reggie Edgerton, a professor of neurobiology and physiological sciences at the David Geffen School of Medicine at UCLA.

Edgerton stresses that the key finding here is that the rats’ legs were able to support their full weight.

"Previous studies have tried to tap into this circuitry to help victims of spinal cord injury. While other researchers have elicited similar leg movements in people with complete spinal injuries, they have not achieved full weight-bearing and sustained stepping as we have in our study."

Technology may be able to help bridge the gap that spinal cord injuries cause between the brain and rhythmic walking circuitry. Neuro-prosthetic devices could activate that circuitry to help the paralyzed regain control over their legs.