Researchers studying brains want to know what's happening in an area called the premotor cortex — the place in the brain that gears up for something the body is about to do, like swimming. Above, Michael Phelps dives off the starting blocks in the final heat of the men's 400-meter individual medley during the 2012 U.S. Olympic Swimming Team Trials in Omaha, Neb., on June 25. Jamie Squire/Getty Images hide caption

itoggle caption Jamie Squire/Getty Images

Unrefrigerated brains in preserving solution are stacked high on shelves at the Harvard Brain Tissue Resource Center at McLean Hospital. Olin College of Engineering/Flickr hide caption

itoggle caption Olin College of Engineering/Flickr

This image shows the grid structure of the major pathways of the brain. It was created using a scanner that's part of the Human Connectome Project, a five-year effort which is studying and mapping the human brain. MGH-UCLA Human Connectome Project hide caption

itoggle caption MGH-UCLA Human Connectome Project

The most common cause of brain injury in premature infants is a lack of oxygen in the days and weeks after birth, researchers say. Ibrahim Usta/AP hide caption

itoggle caption Ibrahim Usta/AP