The MRI machine in Dr. Owen Carmichael's lab blares as it scans a subject's brain. Carmichael, Director of Biomedical Imaging at Pennington Research Center, studies those scans trying to understand how the brain ages.
Carmichael explains that "what you'll see on the MRI scan is the amount of brain tissue. And all of that brain tissue is part of that electrical circuitry that makes it possible for you to think." As we age, our brains tend to shrink. And as that tissue goes away, the harder it becomes to think.
He describes the young brain as a grape that's just been pulled from the vine, while "the elderly brain looks more like a raisin, in that it's deflated and smaller in size. And the person with Alzheimer's, that 'looking like a grape' goes even further, it's extremely shriveled up."