Gert-Jan Oskam was living in China in 2011 when he was paralyzed from the hips down in a motorcycle accident. Now, with a combination of devices, the scientists have given her control over his lower body again.

“For 12 years I have been trying to recover,” Mr Oskam said at a news conference on Tuesday. “Now I have learned to walk normally, naturally.”

in a study Published 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 the injured sections. The discovery enabled Mr. Oskam, 40, to stand, walk and climb a steep ramp with only the aid of a walker. Over a year after the implant was inserted, he has retained these abilities and has, in fact, shown signs of neurological recovery, walking on crutches even when the implant was turned off.

“We captured Gert-Jan’s thoughts and translated these thoughts into stimulation of the spinal cord to restore voluntary movement,” Grégoire Courtine, a spinal cord specialist at the Swiss Federal Institute of Technology, Lausanne, who helped lead the research, said in Press conference.

Jocelyne Bloch, a neuroscientist at the University of Lausanne who placed the implant in Mr Oskam, added: “At first it was quite science fiction for me, but today it became reality.”

There have been a number of advances in the technological treatment of spinal cord injuries in recent decades. In 2016, a group of scientists led by Dr. Courtine was able to restore the ability to walk in paralyzed monkeys, and another helped a man regain control of his crippled hand. In 2018, a different group of scientists, also led by Dr. Courtine, devised a way to stimulate the brain with electrical pulse generators, allowing partially paralyzed people to walk and cycle again. Last year, more advanced Brain stimulation procedures allowed paralyzed subjects to swim, walk, and bike in a single treatment day.

Mr. Oskam had undergone stimulation procedures in previous years and had even regained some ability to walk, but ultimately his improvement stalled. At the press conference, Mr. Oskam said that these stimulation technologies had left him feeling that there was something strange about locomotion, an odd distance between his mind and his body.

The new interface changed this, he said: “The stimulation used to control me, and now I control the stimulation.”

In the new study, the brain-spine interface, as the researchers called it, took advantage of an artificial intelligence thought decoder to read Mr Oskam’s intentions, detectable as electrical signals in his brain, and relate them to muscle movements. The etiology of natural movement, from thought to intention and action, was preserved. The only addition, as described by Dr. Courtine, was the digital bridge that spanned the injured parts of the spine.

Andrew Jackson, a neuroscientist at Newcastle University who was not involved in the study, said: “It raises interesting questions about autonomy and the source of commands. You continue to blur the philosophical line between what is the brain and what is technology.”

Dr. Jackson added that scientists in the field had been theorizing about connecting the brain to spinal cord stimulators for decades, but this represented the first time they had achieved such success in a human patient. “It’s easy to say, it’s much harder to do,” he said.

To achieve this result, the researchers first implanted electrodes into Mr. Oskam’s skull and spine. The team then used a machine learning program to observe which parts of his brain lit up as he tried to move different parts of his body. This thought decoder was able to match the activity of certain electrodes to particular intentions: one setting turned on whenever Mr. Oskam tried to move his ankles, another when he tried to move his hips.

The researchers then used another algorithm to connect the brain implant to the spinal implant, which was configured to send electrical signals to different parts of his body, causing movement. The algorithm was able to account for slight variations in the direction and speed of each muscle contraction and relaxation. And, because the signals between the brain and the spinal cord were sent every 300 milliseconds, Mr. Oskam was able to quickly adjust his strategy based on what worked and what didn’t. Within the first treatment session, he was able to twist his hip muscles.

Over the next few months, the researchers fine-tuned the brain-spine interface to better accommodate basic actions like walking and standing. Mr. Oskam achieved a somewhat healthy-seeming gait and was able to traverse steps and ramps with relative ease, even after months without treatment. In addition, after a year of treatment, he began to notice clear improvements in his movement without the help of the brain-spine interface. The researchers documented these improvements on weight-bearing, balance, and walking tests.

Now, Mr. Oskam can walk around his house in limited ways, get in and out of a car, and stop at a bar for a drink. For the first time, he said, he feels that he is the one in control.

The researchers acknowledged the limitations of their work. Subtle intentions in the brain are hard to discern, and while the current brain-spine interface is adequate for walking, the same probably cannot be said for restoring upper-body movement. The treatment is also invasive, requiring multiple surgeries and hours of physical therapy. The current system does not solve all spinal cord paralysis.

But the team was hopeful that further advances would make the treatment more accessible and consistently more effective. “This is our true goal,” Dr. Courtine said, “to make this technology available worldwide to all patients who need it.”