Sam Swiller and his dog, Sully, in their home in Washington, D.C. Meredith Rizzo/NPR hide caption

itoggle caption Meredith Rizzo/NPR

The Allen Cell Types Database catalogs all sorts of details about each type of brain cell, including its shape and electrical activity. These cells, taken from the visual area of a mouse brain, are colored according to the patterns of electrical activity they produce. Courtesy of Allen Institute for Brain Science hide caption

itoggle caption Courtesy of Allen Institute for Brain Science

The ill-fated Sultana in Helena, Ark., just before it exploded on April 27, 1865, with about 2,500 people aboard. Most were Union soldiers, newly released from Confederate prison camps. Library of Congress hide caption

itoggle caption Library of Congress

A color-enhanced cerebral MRI showing a glioma tumor. Scott Camazine/Science Source hide caption

itoggle caption Scott Camazine/Science Source

To sleep, perchance to consolidate important connections in far-flung parts of the brain. Alberto Ruggieri/Illustration Works/Getty Images hide caption

itoggle caption Alberto Ruggieri/Illustration Works/Getty Images

The same nerve receptor that responds to the green paste on your sushi plate is activated by car exhaust, the smoke of a wildfire, tear gas and other chemical irritants. iStockphoto hide caption

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The Allen Institute for Brain Science hosted its first BigNeuron Hackathon in Beijing earlier this month. Similar events are planned for the U.S. and U.K. Courtesy of Allen Institute for Brain Science hide caption

itoggle caption Courtesy of Allen Institute for Brain Science

About twice a year, statistics suggest, a pilot somewhere in the world — usually flying alone — deliberately crashes a plane. The Germanwing flight downed last week may be one such case. But most people who fit the psychological profile of the pilots in these very rare events never have problems while flying. Patrik Stollarz/AFP/Getty Images hide caption

itoggle caption Patrik Stollarz/AFP/Getty Images

A simulation from the Neitz lab of what colorblindness looks like, with normal color vision on the left and red-green colorblindness on the right. Courtesy of Neitz Laboratory hide caption

itoggle caption Courtesy of Neitz Laboratory

When combined with results of other neurological tests, and in the context of a thorough medical history, atrophy of the brain (shown here in an MRI scan) sometimes indicates Alzheimer's. Simon Fraser/Science Source hide caption

itoggle caption Simon Fraser/Science Source

Jonathan Keleher talks with a colleague, Rafael Wainhaus, at work. Keleher was born without a cerebellum, but his brain has developed work-arounds for solving problems of balance and abstract thought. Ellen Webber for NPR hide caption

itoggle caption Ellen Webber for NPR

Jonathan Keleher is one of a handful of people who have lived their entire lives without a cerebellum. Ellen Webber for NPR hide caption

itoggle caption Ellen Webber for NPR

Prion protein can be infectious, spreading from cell to cell in the brain. Here four nerve cells in a mouse illustrate how infectious prion protein moves within cells along neurites — wire-like connections the nerve cells use for communicating with adjacent cells. Science Source hide caption

itoggle caption Science Source