You can thank my mother for this.  She gives me a subscription to National Geographic for my birthday.  Each year she asks if I’d still like to get it.  Here’s one reason I always answer “yes.”

The January 2010 issue includes A Better Life with Bionics.  Joel Fischman’s article  starts with Amanda Kitts (pictured at right ), who lost most of her left arm in an auto accident in 2006.  Kitts one of the people on the front lines of bionics because of her collaboration with the Rehabilitation Institute of Chicago‘s Todd Kuiken.

Traditional prosthetic arms, the article says, rely on cables: the individual presses a lever on a harness to make one of three movements of the pincer hand.  In Kitts’s case, Kuiken “rewired” nerves that used to go all the way down her arm.  That’s reinnervation (New York Times graphic).

The nerves started in Kitts’s brain…which holds a rough map of the body…. In an intricate operation, a surgeon rerouted those nerves to different regions of Kitts’s upper-arm muscles…

“By four months, I could actually feel different parts of my hand when I touched my upper arm.  I could touch it in different places and feel different fingers,” [says Kitts.]

That was the start.  Kitts then received a new bionic arm with electrodes that could pick up electrical signals from those muscles.  How does it know which signals?  Because Kitts also has a phantom arm–a set of electrodes controlling a virtual arm in a computer–that RIC’s Blair Lock uses to fine-turn the connection between muscle signal and the desired motion.

So, how does it do?  Here’s Kitts in the lab.  (Note: there’s no sound in this video.)

Related items:

• Amanda Kitts’s Patient Story (from the Rehabilitation Institute of Chicago)
• Prosthetic Limb Advance (from NPR’s Science Friday; includes video of bionic arm in use)
• The Bionic Body (interactive graphic at the National Geographic)
• In New Procedure, Artificial Arm Listens to Brain (New York Times, Feb. 10, 2009)