Claudia Mitchell, who had her left arm amputated at the shoulder after a motorcycle accident, can now grab a drawer pull with her prosthetic hand by thinking, "grab drawer pull." She is the first woman to be fitted with the “bionic arm” technology. That a person can successfully control multiple, complex movements of a prosthetic limb with his or her thoughts opens up a world of possibility for amputees.
The "bionic arm" technology is possible primarily because of two facts of amputation. First, the motor cortex in the brain (the area that controls voluntary muscle movements) is still sending out control signals even if certain voluntary muscles are no longer available for control; and second, when doctors amputate a limb, they don't remove all of the nerves that once carried signals to that limb. So if a person's arm is gone, there are working nerve stubs that end in the shoulder and simply have nowhere to send their information. If those nerve endings can be redirected to a working muscle group, then when a person thinks "grab handle with hand," and the brain sends out the corresponding signals to the nerves that should communicate with the hand, those signals end up at the working muscle group instead of at the dead end of the shoulder.
How can someone control a machine with
their thoughts
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Claudia Mitchell with her bionic arm
Video - Surgeon and engineer Todd Kuiken talks about the bionic arm