 |
 |
Brain Implants Move at the Speed of Thought New Devices Operate on the Power of Thought Alone, Testing Beginning in Humans By Jennifer Warner - WebMD Medical News Reviewed By Michael Smith, MD on Thursday, April 15, 2004 April 15, 2004 -- It may sound like science fiction, but brain implants that generate action based on the power of human thought are about to become reality. This week the FDA approved the first clinical trial of such a device in paralyzed people. The device, called the BrainGate system, uses a tiny silicone chip and electrodes implanted in the brain designed to allow people who can't move to operate a computer with their thoughts. Previous studies of the device in monkeys showed that it allowed the animals to use their brains to control cursor movements on a computer screen. Experts say this is just the first of many such brain implants that will be moving from the drawing board and animal testing to clinical trials in humans in the not-so-distant future. The hope is that these devices may eventually help people with movement problems caused by spinal cord injury, stroke, Lou Gehrig's disease, and other disorders, communicate better and gain greater independence. Researchers say the advances made in treating disabled and impaired people with brain implants may also have much broader implications in treating a wide range of ailments -- from depression to cerebral palsy. "There's something for the benefit of everybody with a better understanding of how the brain works," says Eric Braverman, MD, director of the Place for Achieving Total Health (PATH) in New York City. But experts say the more immediate challenge will be translating the information gained in this first-ever trial of thought-controlled devices in humans into technologies that may restore movement in paralyzed people. "It's a big step from controlling a computer cursor to ultimately controlling a robot arm or an artificial limb," says neurologist John W. Krakauer, MD, assistant professor of medicine at Columbia University in New York City. "It's not just a little bit more difficult, but it's a categorically more difficult problem." Thinking Makes Them Work Although brain implants that send electrical shocks to the brain have been used for several years to improve muscle control in people with Parkinson's disease, this new generation of brain implants does not deliver electricity to brain. Instead, they harness the brain's own electrical current and use it to create movement, such as moving a cursor across a computer screen. The implants are designed to help people who have lost muscle function but still have an intact brain that is capable of producing movement commands. They bypass the damaged nerves and muscles that no longer work and transmit the commands from the brain to external sensors that are then interpreted by a computer interface. The BrainGate system, created by Cyberkinetics Inc. of Foxborough, Mass., consists of an internal sensor implanted in the brain that carries signals to external processors via wires running through the skull. The sensor itself is smaller than a baby aspirin and has 100 electrode sensors -- each thinner than a hair -- that detect electrical activity in the brain. A similar device known as the Brain Communicator is under development at Neural Signals in Atlanta. Researchers say the device can operate using either a single electrode implanted under the brain's surface or a conductive skull screw that does not enter the brain and records signals from the surface. The major difference between the Brain Communicator and the BrainGate system is that the Brain Communicator uses wireless technology to transmit signals to external processors rather than requiring the user to have wires protruding from their head, which could pose an infection risk. Cyberkinetics says they plan to introduce an updated, fully implated version of the BrainGate that will make use of wireless technology before marketing the device. The year-long, phase I clinical trial of the device will involve five quadriplegics who have been paralyzed for at least two years but are still able to talk. Tim Surgenor, president and CEO of Cyberkinetics says having study participants who can communicate will facilitate testing and refinement of the device by allowing them to provide feedback about how it's working. Even though the quadriplegics involved in this initial trial of the device may also be eligible to use voice-activated or tongue switch devices to operate a computer, Surgenor says the limitation of current technology is that these devices are not under their control and have to be mounted by someone else. "We view that for these patients the computer can be a gateway for lots of things in their life," Surgenor tells WebMD. "In terms of moving their own arm, robotics, or almost any application you can think of, the first step would be using a computer, and we're focused on that first step." Translating Thought Into Movement Both the BrainGate and Brain Communicator are designed to translate brain signals into actions on a computer, but the next step will be to develop devices that can transform thoughts into movements of muscles or robotic limbs. "There are a very large number of challenges that are going to face having people controlling a real limb. Moving a cursor is just one task in two dimensions," says Krakauer. "If you're going to have someone use a robot arm, they're going to have to be doing all sorts of different tasks with it, combing their hair, opening a door, etc., and it may well be that a small number of neurons isn't sufficient for the whole multiplicity of tasks that might be required." Researchers at Duke University recently reported progress in that area in animal studies. Neurobiologist Miguel Nicolelis, MD, PhD, and his colleagues at Duke have already successfully taught rhesus monkeys to consciously control the movements of a robotic arm using only signals from their brains. Now they are developing a prototype neuroprosthetic device for use in humans and have applied for federal approval for implanting electrodes in quadriplegic patients. The implants being studied in primates are much more complex and involve sampling brain activity from many more regions than the ones being studied in humans. Krakauer says that eventually these human studies using brain implants to move a computer cursor and the increasingly sophisticated experiments in primates using implants to move robotic limbs will converge. He says it could happen in as little as five to 10 years, depending on the success and excitement generated by the BrainGate clinical trial. Cyberkinetics' Surgenor says the company plans to begin a second clinical trial next year and have a product ready to take to market by 2007, pending FDA approval. "It really is just the first step in terms of seeing how the product works and developing a commercial product," says Surgenor. "It's an important milestone, but it's not the end of road. It's really in some ways the beginning of the road in working with humans." SOURCES: Eric Braverman, MD, director, Place for Achieving Total Health (PATH), New York City. John W. Krakauer, MD, assistant professor of medicine, Columbia University, New York City. Tim Surgenor, president and CEO, Cyberkinetics, Foxborough, Mass. Nicolelis, M. PLoS Biology, Oct. 13, 2003; vol 1: pp 193-208. News release, Duke University. News release, Neural Signals. News release, Cyberkinetics. American Academy of Neurology. SOURCE: WebMD http://tinyurl.com/2atp7 * * * ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn