Dr. Andrew Ko performed brain surgery on Genette Hofmann at Harborview Medical Center in Seattle in hopes of reducing the epileptic seizures that had disrupted Hofmann’s life for decades. At the same time, Hofmann agreed to donate a small bit of her healthy brain tissue to researchers at the Allen Institute, who were eager to study brain cells while they were still alive, joining a long line of epilepsy patients who’ve helped scientists reveal basic secrets of the brain.