Over the past year, scientists have made great strides in the development of brain-machine interfaces (BMIs), wired external devices that are controlled solely by brain activity [see “Roadmapping the Adoption of Brain-Machine Interfaces”]. Last October, Nathan Copeland, a man who had been paralyzed from the chest down for more than 10 years, made headlines when he fist-bumped President Obama with a BMI-controlled robotic arm using only his thoughts. As BMI-related technologies and neuroprosthetics become more sophisticated, researchers are learning that these tools can make some fascinating changes to the brain, engaging its natural plasticity in sometimes unanticipated ways. Understanding those changes to underlying plasticity, some say, could offer clues to how to rewire and rehabilitate the damaged brain—perhaps even without the need of external hardware. Prosthetics, even without the addition of a BMI component, can alter the brain’s connections, says Lewis Wheaton, director of the Cognitive Motor Control Lab at the Georgia Institute of Technology says.