Where is the real Matrix?

Neural implant devices are now a reality. But misguided federal policies are keeping them from the people who need them.

By Shy Shoham and Sam Hall

Nov 11, 2003 | In the futuristic vision of the Wachowski brothers' movie trilogy "The Matrix," humans dive into a virtual world by connecting their brains directly to a computer. Most movie viewers may consider direct interfaces with the nervous system as much of a fantasy as the movie's gravity-defying special effects. However, for a small group of engineers and scientists this very idea is very real -- and is driving advances in medical technology that could help millions of disabled people see and hear -- and live normal lives. Unfortunately, bureaucratic hurdles have slowed the development of this technology, and its potential remains largely untapped.

Real-life human-computer interfaces are called neuroprostheses -- medical devices that connect directly to the human brain, spinal cord or nerves. "Matrix" fans might be surprised to learn that neuroprostheses have been around as long as more "traditional" devices like cardiac pacemakers. In fact, a number of neuroprosthetic devices were already being developed in the 1950s, and by the early 1970s the National Institutes of Health established the Neural Prostheses Program to coordinate research in this promising field.

The first neuroprostheses to become commercially available in the United States were cochlear implants, following their initial FDA approval in 1984. Sound from a microphone placed near the ear is coverted to weak electrical currents that activate auditory nerve endings inside the cochlea in the inner ear. The activity produced in these nerves propagates directly to the brain, where it produces an auditory perception. By bypassing the normal hearing apparatus it provides an artificial hearing sensation to deaf people. To date, more than 55,000 patients worldwide have received cochlear implants. The technology of cochlear implants has enjoyed remarkable advances since the early days. Improvements in signal processing now allow many deaf users to use these devices to perceive speech, talk on the phone, and even listen to music.

While sensory prostheses like the cochlear implant provide a substitute sensory percept, motor prostheses are used to move muscles -- allowing the paralyzed to regain lost function. One example of a motor prosthesis is the FreeHand system from NeuroControl Corp., which uses implanted muscle stimulators to restore limited hand movement in individuals paralyzed as a result of certain forms of spinal cord injury. The user of this system controls it with a controller-stimulator unit implanted behind his shoulder. Limb-control systems like the FreeHand system have been implanted in more than 300 patients.

The most widely used motor neuroprostheses are devices used to stimulate the bladder in paralyzed individuals who have lost control of bladder voiding. Thousands of such devices have been implanted worldwide for over three decades.

A very different use of neuroprosthetic devices is to disrupt unwanted brain activity, which can be the result of different neurological diseases. These devices target the tremors that result from Parkinson's disease, essential tremor, seizures that result from epilepsy, and chronic, persistent pain (which has a variety of causes). They are implanted in patients that are not responding to medication. Anti-tremor devices are implanted by neurosurgeons in the patient's brain, in a region called the basal ganglia. More than 15,000 patients have been implanted with such deep-brain stimulators. Anti-epileptic devices are implanted in the patient's neck region around the vagus nerve. Over 18,000 patients have been implanted with vagus-nerve stimulators to date. Devices for chronic pain have been implanted in a variety of regions, most commonly in the spinal cord.

Next Page: Spectacular advances in neuroprosthetics await us, but bureaucracy is stifling the field

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