“They dream of an anti-Alzheimer's pill that regenerates neurons to keep memory intact. "There has to be some kind of chemical stuff in the [hippo-campus] that is sensing exercise and saying, OK, let's start cranking out new cells," says Columbia University neurologist Scott Small, who recently used a novel MRI technique to track neurogenesis in live human subjects. "If we can identify those molecular pathways, we might be able to think of clever ways to induce neurogenesis biochemically."”