This summer the United States Food and Drug Administration (FDA) approved three devices intended to replace or supplement neurological function in people who are disabled. Two medical device companies are now marketing "brain pacemakers" to control epileptic seizures and to quiet the tremors of Parkinson's disease, and a third is selling a device that allows paraplegics limited control of their hands. Other neural prosthetics, most notably the cochlear implant, which can return a sense of hearing to some deaf people, have been in clinical use for years.
But researchers aren't resting on their laurels. Improvements are under way in all of these devices, and many others are in various stages of development. While most of the current devices perform relatively simple stimulation of peripheral nerves or deep brain structures, some researchers believe the world is not far from a science-fiction future in which silicon chips performing advanced computations will be ...
