Well, this is pretty freakin’ amazing. Researchers at the University of Louisville’s Kentucky Spinal Cord Injury Research Center have been testing a groundbreaking electrical spinal cord implant for the past few years, and so far, four test subjects — all with total paralysis in their legs — have recorded movement in their legs. And not just small movements, either. All four patients can move their legs and toes, and have lifted weights of up to 100 kilograms (about 220 pounds). We’re no scientists, so we’ll let the folks at New Scientist explain how it works:

The device – an array of electrodes – is implanted not at the point of injury, but in the still intact lumbosacral region of the spinal cord, which is the main information hub linking the brain to the lower limbs. Despite being crushed, (researcher Claudia) Angeli says, the spinal cord and its associated nerve connections retain huge capacity to continue sending messages…

…the implant restores what in healthy people would be the resting potential of the spinal cord, the baseline electrical activity that keeps the cord alert, but which wanes through lack of use in people who are paralysed.

Once this background electrical impetus is restored artificially, the cord reawakens and can register the brain’s “intent” to move from the brain and convert this into fine movement at the motor neuron level. And by modulating the voltage for each individual and for each task, algorithms that optimise delivery of electrical activity for specific movement can be worked out and applied at will by the patients.

In addition to the leg movement, patients have also reported — to varying degrees — restored bladder, bowel and sexual function. The team hopes to continue research on eight new subjects, in conjunction with ongoing animal studies, to achieve the ultimate goal of restoring the ability to walk.