How well do we understand the neurology of learning? Why does the brain's ability to learn diminish as we age? Can science find a way to extend brain "fitness," even for the very old? This program addresses those questions as it describes important medical experiments and studies. Topics include the central role of nerve cell connections in learning and cognitive development; cerebral plasticity, or the breakdown of unused connections; and growing evidence that plaque, diet, and poor blood circulation all "age" the brain. Tests at Germany's Max Planck Institute and the University of Zurich highlight comparisons between healthy and Alzheimer-afflicted brains while assessing the potential for an Alzheimer's vaccine.