Two monkeys have learned to adopt artificial arms as their own, controlling them only with brain activity. Paralyzed humans can control cursors on computer screens with their brain waves. Research released online by the journal Nature suggests they could do the same thing with artificial arms, legs or other prosthetics. This could be good news for those with paralyzing conditions, including veterans returning from Iraq and Afghanistan. John Kalaska is a professor of Neuroscience at the University of Montreal.