When a person loses a leg above the knee, the nerves that once moved that leg don’t simply go quiet. They keep firing. The brain still sends signals down through what remains, still attempts to flex the ankle, extend the knee, curl the toes, even when none of those structures exist anymore. The signals travel to the end of what’s left and stop there, carrying movement instructions that have nowhere to go. For decades, those signals were essentially inaccessible, too faint and too difficult to interpret reliably. Prosthetic legs, unlike their arm counterparts, have largely operated on autopilot, using mechanical systems and built-in sensors to approximate walking without any direct input from the user’s own nervous system. In a study published in Nature Communications, the researchers describe the first successful decoding of leg movement signals recorded directly from the remaining nerves of people with above-knee amputations. Using hair-thin implantable electrodes and an AI system designed to process signals the way biological neurons do, they extracted not just broad movement categories but precise, detailed intentions, including …