A bicycle accident left him a quadriplegic ten years ago, unable to walk. Today Gert-Jan (who does not wish to give his name), 40, has regained natural control over the movement of his legs, can stand and even climb stairs. A feat achieved thanks to a brain-machine interface allowing you to transform your thoughts into concrete actions – the result of a collaboration between Swiss and French researchers.
After having succeeded in making paraplegic patients walk again using electrical stimulation of the spinal cord, then activated using remote controls, a new step was taken by the teams of Jocelyne Bloch and Grégoire Courtine, both professors at the University of Lausanne, the Ecole polytechnique fédérale de Lausanne and the Center hospitalier universitaire vaudois, as well as by their colleagues from the Swiss research center NeuroRestore and the Clinatec research center in Grenoble. Their case study, published Wednesday, May 24 in the journal Nature, shows how a wireless digital bridge between the brain and the spinal cord transmits movement intentions decoded from brain recordings, and then converts them into electrical stimulation activating leg muscles.
“In our previous trials, the way the muscles were stimulated could be compared to an “on-off” modeillustrates Grégoire Courtine. From now on, their activation is decided by the patient. This is why walking is much softer, more fluid. “With the previous technology, for example, it was very difficult to climb stairsadds neurosurgeon Jocelyne Bloch. From now on, the fact of thinking about carrying out a movement longer or with a greater amplitude makes it possible to walk by adapting to the environment voluntarily. To achieve this result, adding layers of technology was essential. »
Brain signals decoded by a laptop computer
The system comprises, on the one hand, an implant placed on the spinal cord. It consists of a neurostimulator connected to a field of electrodes to control the movement of the legs. On the other hand, two wireless electronic recording devices, 5 centimeters in diameter and composed of 64 electrodes each, were implanted on the patient’s head. They are arranged under the skin, in place of part of the cranial box at the level of the motor cortex, an area devoted to the control of voluntary movements of the body.