When mind meets machine

Transcription

1 Adverti Will off-the-shelf body parts routinely replace injured or diseased tissue? Today, there's no one person who has all the gear shown in this Science cover illustration - but such thoroughly bionic humans could well be on the horizon. When mind meets machine Yo dr More Researchers forging connections between brain and bionic devices By Kathleen Wren SCIENCE WASHINGTON, Feb. 7 Once the stuff of science fiction and 1970s television, the idea of engineering replacement parts for the human body is making its way toward reality. Scientists around the world are working on all kinds of bionic spare parts, including groundbreaking technologies that communicate in near-real time with the brain. 1 of 8 4/10/2002 8:27 AM

2 Yellow Pages Auctions at ubid Personals Channel Shopping Newsletters Weather Advertisement AS RESEARCHERS explain in a special bionics issue of the journal Science, published Friday by the American Association for the Advancement of Science, there are major challenges but also exciting possibilities ahead for mind-machine communication. While the next-generation techniques to restore vision, hearing, and mobility are at different stages of development, they all involve the same principle. If there is a defect in a part of the nervous system that converts outside information into electrical messages for the brain, or vice versa, then it should be possible to bypass the defect with technology that can do the translation. MACHINE-ASSISTED MOVEMENT Research is under way to develop brain-computer interfaces that would allow individuals to control artificial or paralyzed limbs by thinking about moving them. William Craelius of Rutgers University has outlined some of the latest research efforts on this front in his Science article. While engineering these devices will pose significant technical challenges, the primary task now is to improve communication between mind and machine, according to Craelius. 2 of 8 4/10/2002 8:27 AM

3 A person with nerve damage in the spinal cord can grasp objects when his or her forearm muscles are activated by a device like this one. A computer "reads" the intention to grasp, and delivers electrical pulses to the necessary muscles via wire coils around the arm. Scientists have already demonstrated that it is possible to use electrodes to detect certain patterns of brain activity. A computer then recognizes these patterns as movement commands and directs a robotic arm to make simple movements, such as grasping. It may be possible to produce more complex movements by decoding neural signals arriving at the limb, instead of those emerging from the brain. In Craelius lab and elsewhere, researchers are trying to record the electrical changes that take place throughout an amputee s residual limb, as he or she imagines making various movements with the missing part. This information would then be used to train a computer to direct a prosthesis, such as an artificial hand, to make those movements. This technique allows movement toward natural biomimetic control. The individuals aren t thinking about first making this movement, then that movement; they re just thinking about moving their hand, Craelius said. Mobility-restoring technologies wouldn t necessarily have to activate a prosthetic limb, Craelius noted. Some people with paralyzed or weak limbs can use devices that activate their muscles directly with electric currents. These devices would interpret movement commands produced by working body parts. For example, a paraplegic is now able to walk by operating switches on his walker that control a stimulator chip his spinal cord. The chip activates his leg muscles, moving one leg forward, then the next. Such technologies have yet to emulate the complex, graceful motions of the human body. That s the dream to have a built-in rhythmic program that would be like turning on melody, said Craelius. 3 of 8 4/10/2002 8:27 AM

4 December 7, 1999 A remarkable new technology could someday allow blind people to enjoy a measure of sight. NBC s Robert Bazell reports. VISION OF THE FUTURE? Certain preliminary technologies may someday lead to implants in the retina that provide partial vision to people with retinal disease, according to Science author Eberhart Zrenner of the University of Tübingen, in Germany. In a healthy retina, a variety of neural cells and 130 million light-detecting molecules called photoreceptors form a complex information processing circuit. This circuit converts input from an optical image into output, in the form of electrical signals that travel along the optic nerve to the brain. In one type of retinal implant, a mini-camera is positioned outside the eye or in an artificial lens on the eye. Information about the image travels to a chip on top of the retina that translates the information into output pulses that stimulate the optic nerve. Developing the computing technology to accomplish this is proving to be a challenge. We need a computer that mimics the retina and reduces visual information to a neuronal image that the brain can understand, Zrenner said. Zrenner and other researchers are working on a different type of device, which activates the retina at the input stage of processing. In this case, an array of minute photodiodes, which generate current in response to light, would be inserted under the retina. Research on animals with such implants has shown that when light enters the eye, it stimulates the retinal 4 of 8 4/10/2002 8:27 AM

5 processing machinery and the connected brain cells. Neither approach would necessarily provide normal vision, but the primary goal is to allow people to see form and light, and thereby gain mobility and self-reliance, Zrenner said. It makes so much difference for a patient to know where the window is in a room, or to see the illuminated entrance of a door. It s a very big difference from seeing nothing to recognizing an area of strong contrast between light and dark, and to recognize larger objects, he said. Nor is it clear when if ever these devices will benefit humans. We have to put the elements we need for application into place, Zrenner said. Only when we have confidence that a patient would benefit would we be willing to apply it. We must also be confident that the implant would function for long time and be safe, and that will certainly take a few years before a product for clinical use is available, although animal experiments look promising. Pancreas A glucose sensor in a vein near the heart will test blood-glucose levels and relay that information to an insulin pump in the abdomen. The system will mimic a natural pancreas, automatically releasing the correct amount of insulin. Printable version BEYOND COCHLEAR IMPLANTS 5 of 8 4/10/2002 8:27 AM

6 January 22, 2002 Cochlear implants have helped many who suffer from hearing loss, including Rush Limbaugh. NBC s Robert Bazell reports. Results may come somewhat sooner in the field of auditory brain-stem implants, microelectrode arrays that directly stimulate an auditory processing center in the brain, as Josef Rauschecker of Georgetown University and Robert Shannon at the House Ear Institute in Los Angeles explain in a third Science article. Many deaf people already use cochlear implants, which activate the auditory nerve by stimulating the hair cells in the inner ear. But, some individuals, including those with a genetic disease called neurofibromatosis type 2, don t have functioning auditory nerves, according to Rauschecker and Shannon. Auditory brain-stem implants, or ABIs, may benefit these individuals, because the technology bypasses the cochlea and auditory nerve altogether. The first part of the device is similar to that of a cochlear implant. An external receiver and speech processor transmit sound waves in the form of electrical impulses. The device then sends the signals via electrodes to a processing center in the brain stem, called the ventral cochlear nucleus. So far, the ABI electrodes have been placed on the surface of this structure. They don t seem to help the brain hear different pitch sensations, including those that are necessary to understand speech. That s because different layers of the ventral cochlear nucleus respond to different sound frequencies, and conventional ABIs only stimulate the superficial layers, Rauschecker explained. For a limited time, MSNBC users can read the original studies from Science: Research on bionic limbs Research on bionic eyes Research on bionic ears Sign up for Science News from EurekAlert Bionic ears bring deaf into world of hearing From Newsweek: New heart, new hope "Health Horizons" "Mysteries" on MSNBC ABIs with surface electrodes just produce a low-frequency buzz that is not anything like the rich spectrum 6 of 8 4/10/2002 8:27 AM

7 natural sound has, Rauschecker said. Scientists have designed a new type of ABI, whose electrodes penetrate the various layers of the ventral cochlear nucleus, and may therefore be able to transmit sounds at various pitches, according to Rauschecker. It isn t clear yet whether these ABIs will indeed help patients understand speech, but the answer should be forthcoming. The FDA has approved the first clinical trial of the penetrating ABI in neurofibromatosis type 2 patients, with the first surgery expected sometime this year. All of the bionic technologies described in Science will take a lot of work to perfect, or even improve. None of them will be ready for the public anytime soon. The fact that they even seem possible, however, reveals that a lot of progress has already been made by the American Association for the Advancement of Science Science Online Sci-Fi Channel: The Six Million Dollar Man Sci-Fi Channel: The Bionic Woman Bionic ear brings sound to deaf "Mysteries of the Universe" Science news from MSNBC MSNBC's Health Library New species of whale discovered Scientists see a rice revolution Jeepers creepers! These bugs are big MSNBC VIEWER'S TOP 10 Would you recommend this story to other viewers? not at all highly MSNBC is optimized for Microsoft Internet Explorer Windows Media Player MSNBC Terms, Conditions and Privacy of 8 4/10/2002 8:27 AM

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