It will now be possible for a patient with spinal cord injury to produce brain signals that relay the intention of moving the paralyzed limbs , as signals to an implanted sensor, which is then output as electronic impulses. These impulses enable the user to operate mechanical devices with the help of a computer cursor.
A report appearing in the July 13 issue of Nature includes the first published findings from an ongoing clinical trial of the Brain Gate Neural Interface System, a brain-computer interface device in the early stages of clinical testing at Massachusetts General Hospital (MGH), Spaulding Rehabilitation Hospital and other institutions across the country.
"The broad question we are addressing is whether it's possible for someone with paralysis to use the activity of the motor cortex [the part of the brain responsible for motion] to control an external device," says Leigh Hochberg, MD, PhD, a neurologist at MGH, Spaulding and Brigham and Women's Hospital and lead author of the Nature paper. "There has been a question of how the function of the cortex might change after it was disconnected from the rest of the body by damage to the spinal cord. We're finding that, even years after spinal cord injury, the same signals that originally controlled a limb are available and can be utilized."
The Nature report describes the first participant in these trials, a 25-year-old man who had sustained a spinal cord injury leading to paralysis in all four limbs three years prior to the study. Over a period of nine months, he took part in 57 sessions during which the implanted BrainGate sensor recorded activity in his motor cortex while he imagined moving his paralyzed limbs and then used that imagined motion for several computer-based tasks. Among his accomplishments - completed with little or no learning time - was moving a computer cursor to open simulated e-mail, draw circular shapes and play simple video games. He also was able to open and close a prosthetic hand and use a robotic limb to grasp and move objects.
"This system is giving us, for the first time, the ability to look at and listen to firing patterns of ensembles of individual neurons in the human brain for extended periods of time. We hope the knowledge gained from this work will allow the development of systems that provide improved communication and environmental control for people with paralysis and someday, when combined with neuromuscular stimulators, restore control over their limbs," says Hochberg, an instructor in Neurology at Harvard Medical School and an investigator in neuroscience at Brown. He and his co-authors also note that the system requires significant improvement in reliability and control and that further research is needed before it will be useful outside a research setting.