The first thing most people notice under a dissecting scope is how absurdly small the subject is. A fruit fly larva, barely visible without magnification, pinned open under a stream of saline, its nervous system laid bare beneath a lens built for something a thousand times its size. Few would guess that a disease affecting the human hippocampus has anything to learn from an organism whose entire brain fits on the head of a pin. And yet inside labs like the Mitchell Center for