ann mckee. how do you do?ice to meet you. >> nothing ann mckee is about to tell them will bring nathan back. >> this is looking at it under the microscope and seeing all those dark brown -- >> but the stiles hope this rare gift will teach us more about brain conditions than ever before. >> we have all the confidence that there's something to be learned from it. >> i think i want it to be my life's mission to make sure this doesn't happen to other kids. >> mckee knows how much more vulnerable these young kids may be. when the young developing brain is hit during football, no matter how hard, the brain is rocked. it's like an egg inside a shell. it stretches, the delicate fibers pulled, fluids violently sloshed around the brain, trying to absorb the blow. >> youth are at risk for any changes in that fluid balance, and they may not be able to handle it as well. >> sounds like you're saying they're more at risk than adults. >> oh, absolutely. >> and this is important, no matter how good a helmet is, it can't compl