"Post-stroke patients and to some extent those having experienced spinal cord trauma frequently have to go through rehabilitation in an attempt to reconnect the intention in the brain to move the affected limb and the actual muscle movement," the lead author of the study, Skoltech research intern Ivan Ninenko, commented.

"Our team's achievement is that we designed a training system that brings together all of the following: a virtual reality headset that prompts the patient to initiate a leg motion toward a virtual goal and creates the illusion of independent movement, a neural interface that registers the patient's intention to move, a robot that actually moves the leg in a natural way thanks to our own software, and transcutaneous electrical stimulation of the spinal cord, which, roughly speaking, amplifies the signal from the brain."

The neural interface used by the researchers is an off-the-shelf device, a cap with electrodes picking up the electrical activity of the brain. However, the software part has been augmented by the scientists, who modified the protocol responsible for identifying an intention to move.

The robot, manufactured by KUKA, is an industrial collaborative manipulator equipped with highly accurate torque sensors. It is capable of guiding the patient's leg in the direction corresponding to the goal they choose in the virtual reality. The team wrote special software that enables the robot to emulate natural limb movements, reproducing the trajectory that the leg of a healthy person would follow.