When Walt Whitman first wrote that line in the mid 1800's, he could not have known just how electric the body is! |
| When we think, when we feel, when we taste, and any time we move a muscle, information moves around inside our bodies in the form of minute electrical signals on biological wires called "neurons". In the last few years, biologists have made great strides in detecting and interpreting those signals. | 
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Last September, Jesse Sullivan, a Chicago area man who had lost both
arms in an electrical accident, received a pair of prosthetic arms.
Though Mr. Sullivan had used artificial limbs before, his new pair has
a new feature. His former prostheses, like most, were controlled
mechanically with springs and cables attached to other areas of his body.
Mr. Sullivan was able to manipulate his old artificial limbs by carefully
coordinating the movement of those other areas. But his new arms
are wired directly into his nervous system!
Surgeons implanted wires in Mr. Sullivan shoulder muscles, which were still intact after the accident. These wires were then connected to the miniature computer which controls his new, motorized prostheses. By detecting and responding to the small electrical impulses which Mr. Sullivan would normally use to control his own, natural limbs, his new robotic arms will be able to react to the signals coming from his brain, just as his original arms did. |
| And in early October, a team of scientists from Duke University in
North Carolina took that same process one step farther. Rather than
using an electrical signal which was being sent by the brain to a missing
limb, Miguel A.L. Nicolelis was able to use brain activity itself to control
a robotic arm. Nicolelis led a team of researchers who monitored
a monkey's brain activity when he used a joystick to control a robot arm
in another room. They then programmed a computer to respond to the
signals within the monkey's brain and move the robot for him.
At first, the monkey was given the joystick to hold, even though it was no longer connected to anything. But the monkey quickly realized that he was not controlling the robot with the joystick, but with his brain instead. Soon, the monkey set the joystick aside and began to make the artificial limb move just by thinking about it. |
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| This most recent development offers hope to people whose nervous systems are so badly damaged that they no longer have functional neurons onto which a limb like Mr. Sullivan's could be grafted. |