Scientists give new life to paralyzed limbs by rewiring brain

By rerouting brain signals, researchers restore voluntary movement

Researchers at the University of Washington are working to reroute brain signals in an effort to give paralyzed people the ability to move their limbs again.

By creating an artificial connection between nerve cells in the brain and muscles, scientists say they are restoring voluntary movement to the once-paralyzed limbs, according to a report from the University of Washington in Seattle. The rerouting effectively bypasses damaged nerves in subjects with spinal cord injuries, which generally damage nerves but leave muscles and brain tissue unharmed.

Research that involves making new connections in living brains and even connecting robots to living brains has been gaining a lot of attention in the past year.

Less than a year ago, a scientist at the University of Arizona announced that he had successfully connected a moth's brain to a robot. Charles Higgins, an associate professor at the university, told Computerworld last year that the research will lead to hybrid computers running both technology and living organic tissue. He also said that the hybrid systems could be used to make people with spinal cord injuries mobile again.

And in January, an international group of scientists successfully used a monkey's brain activity to control a humanoid robot. Miguel Nicolelis, a professor of neurobiology at Duke University and lead researcher on the project, said at the time the research may only be a few years away from helping paralyzed people walk again by enabling them to use their thoughts to control exoskeletons attached to their bodies.

In the most recent study out of the University of Washington, scientists conducted a proof of concept experiment by directly stimulating muscles using neuron activity in the motor cortex, which is the part of the brain that controls limb movement.

Eberhard Fetz, a UW professor and a researcher at the Washington National Primate Research Center, reported that by not having to decode complex neural signals to control a computer or robotic, direct muscle stimulation may give people more natural control of their movements.

In their experiments, monkeys were enabled to flex and extend their wrist to play a video game by artificially stimulating arbitrarily chosen motor cortex cells in their brains. The monkeys' wrist nerves were temporarily numbed with a local anesthetic, which paralyzed the muscles, according to the report. But despite the nerve block, the monkeys were still able to control the contraction strength of their wrist muscles. University scientists noted that controlling the strength of the muscle contraction is what allows someone to gently pick up an egg or grab tightly to a handrail.

"Nearly every motor cortex neuron we tested in the brain could be used to control the stimulation of the wrist muscles," said Chet Moritz, a UW senior fellow and lead author on the study. He added that even brain cells initially unrelated to movement could be controlled and used to stimulate muscles.

The university reported that about 10 more years of research will be needed before this research could be applied in human patients.

Copyright © 2008 IDG Communications, Inc.

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