Having proved in 2004 that plugging a sensor into the human brain's motor cortex could turn the thoughts of paralysis victims into action, a team of Brown University scientists now has the green light from the U.S. Food and Drug Administration (FDA) and the Massachusetts General Hospital (MGH) institutional review board to expand its efforts developing technology that reconnects the brain to lifeless limbs.

Brown's BrainGate Neural Interface System—conceived in 2000 with the help of a $4.25-million U.S. Defense Department grant—includes a baby aspirin–size brain sensor containing 100 electrodes, each thinner than a human hair, that connects to the surface of the motor cortex (the part of the brain that enables voluntary movement), registers electrical signals from nearby neurons, and transmits them through gold wires to a set of computers, processors and monitors. (ScientificAmerican.com in 2006 wrote about one patient's experience using BrainGate during its first phase of trials.)

The researchers designed BrainGate to assist those suffering from spinal cord injuries, muscular dystrophy, brain stem stroke, amyotrophic lateral sclerosis (ALS, or Lou Gehrig's Disease), and other motor neuron diseases. During the initial testing five years ago, patients suffering from paralysis demonstrated their ability to use brain signals sent from their motor cortex to control external devices such as computer screen cursors and robotic arms just by thinking about them. "The signals may have been disconnected from the (participant's) limb, but they were still there," says Leigh Hochberg, a Brown associate professor of engineering and a vascular and critical care neurologist at MGH who is helping lead the research.

Due to the high risk of plugging a device directly into the brain, the FDA in 2004 granted the BrainGate system an investigational device exemption so that researchers could begin testing the unit in patients and collect data about its safety and effectiveness. Thanks to the success of those early tests, the researchers last week kicked off a pilot clinical trial, dubbed BrainGate2. Although the technology is similar to what was used in the original testing, the researchers are looking to enlist up to 15 patients this time and gather more information that will help them better understand brain signals as well as "the method by which we decode them," Hochberg says. Since the initial four-person clinical trial launched five years ago, "we have a better appreciation for things that we need to learn."

A successful BrainGate2 trial could open up a number of new possibilities, including the use of a second sensor to stimulate both sides of the motor cortex, says John Donoghue, a Brown neuroscience professor and director of the Brown Institute for Brain Science. Researchers thus far have implanted the sensor in the side of the brain that controls a patient's dominant side—the left cortex for righties and the right cortex for lefties.

BrainGate2 is part of a larger mission to help paralysis victims regain control of their bodies. "We want to reconnect the brain back to the muscles and eventually back to the entire limb," Donoghue says. "We are attempting to recreate parts of the nervous system that have been disconnected from the brain."

Hochberg expects this second phase to last for several years, "depending on what we learn and how quickly we learn it." The research project has received about $8 million in funding over the past three years from a number of organizations, including the National Institutes of Health (NIH) and the U.S. Department of Veterans Affairs.