The Rev. Herman Browne voluntarily quarantined himself for 21 days after his wife's friend tested positive for Ebola. On Sunday, he returned to his church, Trinity Cathedral, to preach to his congregation about Ebola prevention. Jon Hamilton/NPR hide caption

itoggle caption Jon Hamilton/NPR

Dr. Allan Ropper speaks with residents and fellows as they do rounds at the neuroscience intensive care unit at Brigham and Women's Hospital in Boston. M. Scott Brauer for NPR hide caption

itoggle caption M. Scott Brauer for NPR

Justin McCowan, 39, has Down syndrome and lives at home with his parents in Santa Monica, Calif. Benjamin B. Morris for NPR hide caption

itoggle caption Benjamin B. Morris for NPR

Deion Jefferson, 10, and Samuel Jefferson, 7, take turns climbing and jumping off a stack of old tires at the Berkeley Adventure Playground in California. The playground is a half-acre park with a junkyard feel where kids are encouraged to "play wild." David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

In epilepsy, the normal behavior of brain neurons is disturbed. The drug valproic acid appears to help the brain replenish a key chemical, preventing seizures. David Mack/Science Source hide caption

itoggle caption David Mack/Science Source

Klotho (right) is one of the three Greek Fates depicted in this Flemish tapestry at the Victoria and Albert Museum in London. Wikimedia Commons hide caption

itoggle caption Wikimedia Commons