In sighted people, the part of the brain that recognizes faces is linked to the brain's visual system. But in blind people it seems wired to circuits that process sound. Tina Zellmer/Ikon Images/Corbis hide caption

itoggle caption Tina Zellmer/Ikon Images/Corbis

A tangle of protein (green) in this scanning electron micrograph of a brain cell of an Alzheimer's patient lies within the cytoplasm (blue) of the cell. The tangle consists of clumps of a toxic form of tau. Thomas J. Deerinck/Corbis hide caption

itoggle caption Thomas J. Deerinck/Corbis

Mariama and Fomba Kanneh play in an open space in Barkedu, Liberia. With schools closed across the country, many kids spend their time playing outside every day. Tommy Trenchard for NPR hide caption

itoggle caption Tommy Trenchard for NPR

The nursing staff get a break at the Ebola care center run by Doctors Without Borders in Foya, Liberia. The center has helped stop the spread of the virus. Michealeen Doucleff/NPR hide caption

itoggle caption Michealeen Doucleff/NPR

Angie Gardea depends on her job at a hair salon to put food on the table. But because of the Ebola outbreak, business has been slow. Customers are afraid to come in. Michaeleen Doucleff/NPR hide caption

itoggle caption Michaeleen Doucleff/NPR

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

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