"Walking naturally after spinal cord injury using a brain–spine interface"

Here's some truly amazing medical science:

A spinal cord injury interrupts the communication between the brain and the region of the spinal cord that produces walking, leading to paralysis. Here, we restored this communication with a digital bridge between the brain and spinal cord that enabled an individual with chronic tetraplegia to stand and walk naturally in community settings. This brain–spine interface (BSI) consists of fully implanted recording and stimulation systems that establish a direct link between cortical signals and the analogue modulation of epidural electrical stimulation targeting the spinal cord regions involved in the production of walking. . . . The participant reports that the BSI enables natural control over the movements of his legs to stand, walk, climb stairs and even traverse complex terrains. Moreover, neurorehabilitation supported by the BSI improved neurological recovery. The participant regained the ability to walk with crutches overground even when the BSI was switched off. This digital bridge establishes a framework to restore natural control of movement after paralysis.

To back up a bit: Scientists, including the ones responsible for this work, had previously built similar systems to pick up signals within the spinal chord and transmit them past the damaged section to a receiver on the other side. But this never worked very well, and the subjects never felt like they were walking naturally.

So this time they implanted their sensors in the brain. Scientists had previously identified the precise brain regions that formulate instructions to the legs, and the article makes it sound like implanting electrodes to pick up signals there was no big deal. The impulses were converted to a digital signal and transmitted directly to receivers below the spinal damage, which converted them back into analog electrical stimulation of the lower spinal chord. This, they find, works far better than the old method, restoring at least one person to something like natural walking.

NY Times:

In a study published on Wednesday in the journal Nature, researchers in Switzerland described implants that provided a “digital bridge” between Mr. Oskam’s brain and his spinal cord, bypassing injured sections. The discovery allowed Mr. Oskam, 40, to stand, walk and ascend a steep ramp with only the assistance of a walker. More than a year after the implant was inserted, he has retained these abilities and has actually showed signs of neurological recovery, walking with crutches even when the implant was switched off.

“We’ve captured the thoughts of Gert-Jan, and translated these thoughts into a stimulation of the spinal cord to re-establish voluntary movement,” Grégoire Courtine, a spinal cord specialist at the Swiss Federal Institute of Technology, Lausanne, who helped lead the research, said at the press briefing.

Amazing. Even more amazing would be if such a system could restore control of the arms to people who have lost the use of all their limbs, and I can't think of any reason why that wouldn't be possible using this technology.