A few years ago the thought of a robotic limb controlled by a person's mind was the stuff of science fiction. Today, it seems like there's a new breakthrough in bionic technology every week.

A new study published on Tuesday by Nature described one of the more impressive feats we've heard about: A paralyzed man and woman each had chips implanted onto the motor cortex area of the brain that measured their neurons firing as they watched lab technicians move a robotic arm. A computer recorded the pattern of their thinking as they imagined moving the robotic arm and after they had trained the computer, they took control of the arm. For the first time in years, they were able to serve themselves using nothing more than brain power.

This is just the latest in a number of experimental procedures that connect the brain and nervous system to robotic appendages. DARPA, the Pentagon's research and development wing, has been working on this type of technology for injured soldiers for decades, and over the years, the capabilities of a brain-computer interface have grown from allowing a person to move a cursor on a computer screen to move limbs. The first person to move a prosthetic hand was a guy named Matt Nagle, who with the help of a chip implanted in his brain, could "move a prosthetic hand and robotic arm to grab sweets from one person's hand and place them into another." Within three years, Pentagon-funded researchers had developed entire arms that could be controlled by the brain. As Pentagon Channel News reported in 2008:

It's not just arms these days either. Another Pentagon program is outfitting military amputees with new knees and new ankles. They're functional enough that the soliders can go back into battle. Predictably, their bionic limbs are actually stronger and have better endurance than their natural limbs. From WCPO in Cincinnati:

There's also technology that can take the place of eyeballs and send visual signals from an implanted camera directly to the brain, like Canada's "eyeborg" Rob Spence. ITN News has the story:

Today the technology is simple enough that even a child, in this case, Matthew James, can use it. From ITN again: