A hormone that impacts memory in rats likely does the same thing in other animals, like humans. S. Ugur Okcu/iStockphoto.com hide caption

itoggle caption S. Ugur Okcu/iStockphoto.com

High school players will experience more than 40,000 concussions this season. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Severe mental illness among college students has increased dramatically over the last ten years.  The most common problem is anxiety and depression. Allison Rose/iStockphoto.com hide caption

itoggle caption Allison Rose/iStockphoto.com

Emergency personnel work on Jan 8 at the scene where Rep. Gabrielle Giffords, (D-AZ) and others were shot outside a Safeway grocery store in Tucson, Ariz. Nearly anyone at the scene that day will be at risk for post traumatic stress disorder, but it's difficult to predict who will be affected. Matt York/AP hide caption

itoggle caption Matt York/AP

Surrounded by detectives, Lee Harvey Oswald talks to the press as he is led down a corridor of the Dallas police station after the assassination of U.S. President John F. Kennedy. AP hide caption

itoggle caption AP

Joseph Corbett (center), who was convicted of killing millionaire Adolph Coors III, is led to the Jefferson County courthouse in Golden, Colo., in 1961. John F. Urwiller/AP hide caption

itoggle caption John F. Urwiller/AP

Mira Bartok is the author of 28 books for children. The Memory Palace is her first book for adults. Courtesy of the author hide caption

itoggle caption Courtesy of the author

A mother watches a video taken of herself playing with her daughter for Bellevue Hospital's Video Interaction Project. Former hospital employee Brenda Woodford reviews the footage, offering positive feedback and areas for improvement. Courtesy of Children of Bellevue Archives hide caption

itoggle caption Courtesy of Children of Bellevue Archives

Allen Shawn is an American composer who lives in Vermont. Cynthia Locklin via Viking Adult hide caption

itoggle caption Cynthia Locklin via Viking Adult