Talk of the Nation from NPR

When you gaze into your sweetheart's eyes, look for enlarged pupils. Studies show that our pupils dilate when we feel strong emotions. Psychologist Bruno Laeng, of the University of Oslo, explains how scientists are using "pupillometry" and what pupil diameter suggests about mental activity.

NYU psychology professor Gary Marcus took up guitar at the relatively ancient age of 38, by starting with the video game Guitar Hero. Marcus shares his experiences and insights on the science of learning, which he's gathered in a new book Guitar Zero: The New Musician and the Science of Learning.

According to Rolling Stone magazine, sales of vinyl albums continue to grow, setting a new record in 2010. Does vinyl reproduce sound better, or is it just a trend? Two audio experts join guest host John Dankosky to talk about the science of audio, and how perceptions can shape the sound experience.

Reporting in Science, researchers write that an FDA-approved drug for skin cancer had surprising results in mice with Alzheimer's. The drug rapidly cleared up amyloid protein from the brain and improved cognitive function. Co-author Gary Landreth discusses the drug's potential as a therapy for Alzheimer's.

In his book The Science of Yoga: The Risks and the Rewards, New York Times science writer and long-time yoga practitioner William Broad investigates popular health claims about yoga--that it boosts metabolism, for example--and finds that scientific studies tell a different story.

Several times in earth's history continents have collided to form supercontinents only to later break apart. Geologist Ross Mitchell discusses a new study in Nature that predicts in 50 to 200 million years time the Americas and Eurasia will collide to form a supercontinent over the Arctic.

Lt. Col. Daniel Davis ignited a controversy when he wrote that what he saw in Afghanistan "bore no resemblance to rosy official statements by U.S. military leaders." U.S. Rep. Jim McGovern (D-Ma), defense analyst Tom Donnelly and McClatchy Newspapers correspondent Johnathan Landay discuss the realities of the war in Afghanistan.

On September 17, 2011, hundreds of people gathered in Lower Manhattan to protest the growing wealth gap and Wall Street's involvement in the economic crisis. Five months later, most of the Occupy encampments across the country have been disbanded and the future of the movement remains uncertain.

SPIN Magazine is hoping to review 1,500 albums and mixtapes exclusively in 140-character tweets on the SPINReviews Twitter feed in 2012. The music magazine recently abandoned their 80-word reviews for the new Twitter format, which critics think is killing the art of the music review.

Historian Noah Andre Trudeau is known for uncovering secrets of the Civil War. His previous books, Bloody Roads South and Gettysburg, have unveiled information about Gen. William Tecumseh Sherman's march to the sea in 1864, and the legacy of Confederate Gen. Robert E. Lee. Now, in preparation for a book about a largely unexamined period of President Abraham Lincoln's life, Trudeau is in search of witnesses.