The NYTimes reports in Monkey's Control A Mechanical Arm with Their Thoughts that two monkeys learned how to feed themselves with the use of robotic arms, which were attached to electrical sensors in their brains that transmitted signals to control movement. "The more we understand about the brain, the better we'll be able to treat a wide range of brain disorders, everything from Parkinson's disease and paralysis to, eventually, Alzheimer's disease and perhaps even mental illness," said the device creator.