Brain-Computer Interfaces: Has Science Fiction Become Reality?
By: Veterans Health Administration, Research & Development Dept.
When a team led by John Donoghue, PhD, and Leigh Hochberg, MD, PhD, published results from their pilot study of the BrainGate system in Nature in 2006, the headline in one Canadian newspaper proclaimed, "Movement by Thought: Science Fiction to Fact." A London newspaper referred to the trial participant as "the first bionic man." The editors at an Oakland daily were equally impressed, running the headline: "Paralyzed Man Moves Mountains with Mind."
It was hard for even the most serious science journalists to ignore the fascination surrounding the researchers' stunning achievement. The scientists—from Brown University, VA and other institutions—had enabled a 25-year-old man with quadriplegia to operate a computer cursor and perform other tasks solely through his thoughts.
The technology, called BrainGate, uses a tiny sensor implanted in the motor cortex, the part of the brain that controls movement. The sensor, about the size of Lincoln's head on a penny, has 100 hair-thin electrodes that pick up brain signals. The signals are sent to an external decoder that turns them into commands for electronic or robotic devices. For now, the brain implant is wired to a computer, but the researchers hope to go wireless in the future.
Development of the system is spearheaded by Donoghue, a Brown neuroscientist who became affiliated with VA when the agency established its Providence-based Center for Restorative and Regenerative Medicine in 2004. Donoghue is also chief scientific officer at Cyberkinetics Neurotechnology Systems, a company formed by Donoghue and colleagues in 2001 to bring BrainGate to market.
Hochberg, lead author on the landmark Nature paper and the principal investigator on current trials involving BrainGate, admits there has been some hype in media coverage of the technology, but says most reports have been balanced and accurate.
"Overall, many people have been captivated by the potential of the technology. But thankfully, the media has generally been responsible in describing these as early trials [and making clear] that this is a nascent science—that we're really at the beginning of a tremendous period of learning and opportunity in terms of restoring lost function for people with paralysis or limb loss."
'The focus now, for people with spinal cord injury, brain stem stroke, ALS, and other diseases or injuries of the nervous system, is to be able to restore movement and communication.'
Notwithstanding Hochberg's tempered view, it may be fair to say that in the case of brain-computer interfaces, yesterday's science fiction—for example, the 1938 Andre Maurois novel The Thought-Reading Machine—has indeed become today's reality.
Even so, what's been realized by researchers to date has clear boundaries. BrainGate and similar technologies have little applicability with regard to "higher" functions of the human mind: that which is uniquely individual, such as memory, emotions, creativity. "For the moment, that's a theoretical discussion," notes Hochberg. "The technology is not even close to being able to read into memories or thoughts in the general sense. The leading edge of the field is the ability to extract a neural signal that's related to the intention to move one's limb—and thereby a computer cursor—in a particular direction."
And even the notion of "reading thoughts," while not wholly inaccurate, is more a handy catchphrase for the media than a precise description of what the technology is designed to do.
"'Thoughts' is a useful word because it's immediately meaningful to everyone," says Hochberg, "and the concept of being able to 'read thoughts' has been around in science fiction a long time. But that's not what we're doing in our current research. The focus now, for people with spinal cord injury, brain stem stroke, ALS, and other diseases or injuries of the nervous system, is to be able to restore movement and communication."
Hochberg is principal investigator on two BrainGate trials now underway: one involving people with ALS and related motor-neuron diseases, the other for people with spinal cord injury, muscular dystrophy or stroke.
Enabling those with paralysis to move, communicate
The main way in which BrainGate could restore communication for people who have lost motor ability is to enable them to move a computer cursor, which in turn could allow them to use email, the Internet and word processing, or operate a TV set.
Similar results have been achieved through somewhat different means by Dr. Jonathan Wolpaw and colleagues at the Wadsworth Center, part of the New York State Department of Health. Their method relies on EEG technology—electrodes placed on the scalp, not inside the brain. Users wear a breathable cap on their head that contains eight electrodes—down from 64, just a few years ago—wired to a laptop loaded with software that translates the brainwaves into commands for devices.
This approach avoids some of the risks of brain implants, and may eventually prove viable for many patients with disabilities. One drawback with EEG, however, is that the output is less precise than with implants, and users need far more training than with BrainGate to effectively control a cursor.
Yet another method for restoring communication—this one focused on patients who've lost their speaking ability—is being developed by a private Georgia-based company called Neural Signals, Inc., the only other neuroprosthetics group worldwide, to Hochberg's knowledge, that is using recording sensors inside the brain. Their product is a computer-controlled prosthetic device that would be controlled by brain signals and reproduce the sounds of natural speech.
Brain waves may drive natural or artificial limbs
As for enabling movement, BrainGate has already enabled research participants to open and close a robotic arm. This aspect of the work—using brain signals to activate limbs—may benefit from a new $6.5 million grant from the National Institutes of Health to Cyberkinetics, Brown and the Cleveland Functional Electrical Stimulation (FES) Center, which is sponsored jointly by VA and Case Western Reserve University.
The partnership with the FES Center represents an intriguing melding of approaches. Most past FES work has involved people with intact but non-functioning limbs—such as those with spinal cord injury or stroke. Electrodes are implanted not in the brain but in the weakened or paralyzed muscles that would normally move the limb. Small electrical currents from external or implanted devices activate the muscles and restore movement and function. Only recently, research there has expanded to prosthetics applications. In one project, electrodes would be implanted onto intact arm and shoulder muscles near the amputation and pick up brain signals to drive an artificial hand.
The new FES-BrainGate collaboration is "potentially very promising," says Hochberg, in that two groups of patients might benefit: those using prosthetics limbs, and those whose natural limbs are intact but disconnected from the brain and nervous system. Either way, what BrainGate inventor John Donoghue has described as the ultimate goal of the technology—"to reconnect brain to limb"—may eventually be within reach.