A 58-year-old woman paralyzed by a stroke was all smiles after sipping her cinnamon latte with the help of a mind-controlled robotic arm. Cathy Hutchinson is one of two tetraplegic patients able to reach and grasp with a robotic limb linked to [a] tiny sensor in her brain, according to a study published today in the journal Nature. The device, called BrainGate, bypasses the nerve circuits broken by the brainstem stroke and replaces them with wires that run outside Hutchinson's body. The implanted sensor is about the size of a baby aspirin. You can go from the brain ... directly to a device like a computer or a robotic arm," said BrainGate developer John Donoghue, director of the Institute for Brain Science at Brown University in Providence, R.I. "This can help restore independence to a person who was completely reliant on other people for every activity, whether it's brushing their teeth, eating their dinner or taking a drink." Hutchinson, who has been unable to move or speak for 15 years, had the 96-channel sensor implanted in her brain's motor cortex in 2005. Since then, the BrainGate team has been fine-tuning the system to give her back some of the control she lost. With its hair-like electrodes, the BrainGate sensor taps into the flurry of brain activity, recording electrical signals that can be translated into movement commands. "It's like learning a language," Donoghue said of the translation process, a series of mathematical calculations that copy the brain's processing ability.