A chip implanted in a young quadriplegic's brain is already improving his quality of life. Soon the benefits may be more widespread

　　A 25-year-old man unable to move from the neck down recently did what many assumed impossible. After a knife attack that had left him paralyzed, all he could move was his head, which he used to push a switch and summon a nurse. And he could steer his wheelchair by blowing into a straw near his face. That was it.

　　Then last June, a Foxborough (Mass.) company called CyberKinetics opened the man's skull and implanted a special chip no larger than a baby aspirin. That implant has given him a few additional and precious abilities. When hooked to a special computer via a cable, the chip translates the young man's thoughts into commands that let him move a cursor across a PC screen and open e-mail. He can draw a circle with a computer painting program. And he can use a robotic hook to perform simple tasks like picking up a candy and sliding it across a table.

　　All he has to do is think.

　　Welcome to the daunting yet promising world of "thought technology." After more than two decades of research, the use of thoughts to manipulate computers and robots is no longer solely the stuff of science fiction.

　　Several groundbreaking studies, employing brain implants as well as noninvasive methods of reading thoughts, have begun or been completed in the past year. In fact, more than half of the scientific papers in this field, called brain-to-computer interaction (BCI), have been published in the past two years, notes Jonathan Wolpaw, a research physician at Wadsworth Center, the New York State Health Dept.'s research laboratory in upstate Albany.

　　Why now? Credit major advances in information technology as well as brain science. Brain surgeries are no longer rare: Thousands of Parkinson's disease patients have had special devices implanted in their brains to alleviate uncontrollable shaking and other symptoms. The implants themselves have improved, so the body doesn't reject them as furiously. And significant development has been achieved in software used to interpret the brain's signals and convert them into commands understood by computers.

　　But increased demand for thought technology remains the biggest reason for the field's progress. Today, 4 million Americans live with paralysis resulting from any of a wide array of factors including car accidents, strokes, and cerebral palsy, according to the Christopher Reeve Paralysis Foundation. Their numbers could skyrocket as the U.S. population ages.

　　Scientists hope that thought technology will reduce the impact of such disabilities. People with spinal-cord injuries, for example, often lose their ability to walk because the communications network between their brain and their legs has been interrupted. The brain still commands the leg muscles to move, but they don't hear its orders.

　　Thought technology, scientists hope, will bridge this communications gap by sending the brain's command to an implant in the paralyzed legs that would, in turn, relay the message to the muscles. "Our goal is for you to see paralyzed people eating at a restaurant and for you not to know that they are paralyzed," says John Donoghue, founder and chief scientific officer at CyberKinetics.