Monkey mind-controlled arm: It sounds like the name of an awesomely terrible sci-fi film or a fledgling grindcore group, but it's a very real phenomenon, and one that could pay significant dividends for paraplegics everywhere. Neurobiology professor Miguel Nicolelis and his team of researchers at Duke University recently devised a method by which monkeys (and, perhaps one day, humans) can control a virtual arm using only their brains. It's a concept similar to what DARPA has been pursuing with its mind-controlled "Luke" arm, with one important difference: Nicolelis' system not only allows users to remotely execute motor functions, but provides them with near-instantaneous sensory feedback, as well. Most similar techniques use electrode implants to stimulate brain activity, but this can create confusion when a patient's brain sends and receives signals to and from a prosthetic arm. Nicolelis circumvented this problem with a new interface that can read and transmit brain signals to an artificial limb, before switching to a receptive mode in just milliseconds.

After designing the technology, Nicolelis and his colleagues tested it on two, electrode-equipped rhesus monkeys. One set of electrodes was placed in the motor cortex of each animal, with the other implanted within their brains' sensory regions. They then trained the monkeys to look at a three identical objects on a computer screen and to "touch" each object with a virtual arm, controlled by signals sent from the brain electrodes. Only one of the three objects had a so-called "virtual texture," which, if selected with the on-screen arm, would send a sensory signal back to the monkey's brain (while triggering a tasty squirt of fruit juice for the lucky contestant). The two rhesus species ended up passing the test with flying colors, resulting in a "proof of principle" that Nicolelis' system can send tactile signals to the brain in almost real-time. The scientists have already developed a way for monkeys to control the arm wirelessly, and are now embedding their technology within a full-body, mind-controlled exoskeleton for paralyzed patients, as well. Of course, the technology still needs to be tested on actual humans, though Nicolelis seems confident that he and his team have already cleared the most difficult hurdle: "Since we cannot talk to the monkeys, I assume with human patients, it's going to be much easier."