A brain implant combined with electrical stimulation has allowed a paralyzed man to regain some movement and the sensation of touch. The device bypasses the spinal cord injury by directly connecting the brain, muscles, and sensory areas.
Keith Thomas lost the use of his limbs after a diving accident in 2020. He could no longer raise his arms to his face and no longer felt contact on his hands and wrists. In 2023, he joined a clinical trial led by the Feinstein Institutes.
Chad Bouton helps Keith Thomas apply a non-invasive stimulation patch to be worn on the skin, as part of the 'double neural bypass' clinical trial.
Photo credit: Northwell Health
The researchers implanted five networks of microelectrodes in his brain. Some record the signals produced when he imagines a movement. Others stimulate the brain regions that normally process information coming from the hand.
The system forms a 'double neural bypass'. A first link decodes the intention to move and commands stimulators placed on the muscles of the arm. A second transmits to the brain information from sensors placed on the hand and fingers.
When Thomas grasps an object, the sensors detect pressure and contact. The system then converts this information into adapted electrical stimulations. The brain thus receives an artificial signal that can be interpreted as a sensation coming from the hand.
The researchers also developed a method called 'cortical mirroring'. They record brain activity associated with the feeling of being touched, then reproduce some of these signals through stimulation. This approach aims to progressively reactivate circuits that remained silent after the injury.
After several weeks of training, the participant was able to perform precise gestures, such as grasping an empty eggshell without breaking it. He also regained sensations in his right wrist, an area that had been numb since the accident.
The results observed in a single person do not yet allow concluding a generalizable solution. The implantation remains invasive and the system still requires external equipment. Further trials will need to clarify its safety, stability, and efficacy according to different spinal cord injuries.