It's a scene football fans will see over and over during the bowl and NFL playoff seasons: a player, often the quarterback, being slammed to the ground and hitting the back of his head on the landing.
Sure, it hurts, but what happens to the inside of the skull? Researchers and doctors long have relied upon crude approximations made from test dummy crashes or mathematical models that infer – rather loosely – what happens to the brain during traumatic brain injury or concussion.
But the truth is that the state of the art in understanding brain deformation after impact is rather crude and uncertain because such methods don't give any true picture of what happens. Now, mechanical engineers at Washington University in St. Louis and collaborators have devised a technique on humans that for the first time shows just what the brain does when the skull accelerates.
What they've done is use a technique originally developed to measure cardiac deformation to image deformation in human subjects during repeated mild head decelerations. Picture, if you will, a mangled quarterback's occipital bone banging the ground, then rebounding. The researchers have mimicked that very motion with humans on a far milder, gentler, smaller scale and captured the movement inside the brain by magnetic resonance imaging (MRI).

New technique puts brain-imaging research on its head