Controlling movement through thought alone
Posted July 15, 2006on:
A man with paralysis of all four limbs could directly control objects around him – open simulated email, play a game of Pong, adjust the volume on the television set – using only his thoughts. These pilot clinical trial findings, featured on the cover of Nature, mark a major advance in neuroscience, one that offers hope to people with severe motor impairments.
The Nature article is the first to provide in-depth scientific findings from the pilot trial of a device called BrainGate, a brain-to-movement system created and tested by Cyberkinetics Neurotechnology Systems Inc. Cyberkinetics, the forerunner of Cyberkinetics Neurotechnology Systems Inc. was founded in 2001 under a licensing agreement with the Brown University Research Foundation. Brown faculty and students created the company based on research and technology developed in the laboratory of neuroscientist John Donoghue, the Henry Merritt Wriston Professor and director of the Brain Science Program.
BrainGate consists of a surgically implanted sensor that records the activity of dozens of brain cells simultaneously. The system also decodes these signals in real time to control a computer or other external devices. In the future, BrainGate could control wheelchairs or prosthetic limbs. The long-term goal: Pairing BrainGate with a muscle stimulator system – which would allow people with paralysis to move their limbs again.
In the Nature article, the authors describe the experience of the first trial patient, a 25-year-old man with spinal cord injury, as he used the device for nine months of the 12-month study period. The team also discusses the initial performance of a second trial patient, a 55-year-old man with spinal cord injury.
Based on the experience of these patients, the team outlines three key findings:
movement signals persist in the primary motor cortex, the area of the brain responsible for movement, long after a spinal cord injury;
spiking from many neurons – the language of the brain – can be recorded and routed outside the human brain and decoded into command signals;
paralyzed humans can directly and successfully control external devices, such as a computer cursor and robotic limb, using these neural command signals.
“We found that cortical activity can be modulated voluntarily even years after spinal cord injury,” said Leigh Hochberg, M.D., a Brown alumnus and lead author of the article. “Some researchers might have predicted that this part of the brain would alter its function dramatically after the spinal cord was injured. But that doesn’t seem to be the case. The movement-related signals are still there.
“What’s truly exciting is this: The cortical activity of a person with spinal cord injury, controlling a device simply by intending to move his own hand, is similar to the brain activity seen during preclinical studies of monkeys actually using their hands,” Hochberg said. “Whether it is real or attempted movement, neurons seem to respond with similar firing patterns.”
Hochberg is an investigator in neuroscience at Brown and a neurologist at Massachusetts General Hospital, Spaulding Rehabilitation Hospital and Brigham and Women’s Hospital. Hochberg is also an instructor at Harvard Medical School and an associate investigator with the Rehabilitation Research and Development Service at the Providence VA Medical Center.
Donoghue, senior author of the article and chief scientific officer at Cyberkinetics, noted that technical problems arose during the pilot trial, including signal decline after months of recording. However, the patients’ control of the computer cursor and other devices was largely reliable. The first patient, for example, executed simple tasks such as moving a cursor to a target on a computer screen with 75 to 85 percent accuracy over many sessions. He also controlled a robotic arm, picking up pieces of hard candy and dropping them into a technician’s hand.
“What is also encouraging is the immediate response from the brain,” Donoghue said. “When asked to ‘think right’ or ‘think left,’ patients were able to change their neural activity immediately. And their use of the device is seemingly easy. Patients can control the computer cursor and carry on a conversation at the same time, just as we can simultaneously talk and use our computers.”
BrainGate is based on more than a decade of basic neuroscience research in the Donoghue lab, much of it funded by the National Institute of Neurological Disorders and Stroke, and much of it conducted by students. After proving the concept for BrainGate in experiments with monkeys, Donoghue and three Brown colleagues created Cyberkinetics to take their idea from bench to clinical trial.
Source: Brown University