River of dreams

The hippocampus is a region of the mammalian brain involved in learning and memory. In this confocal microscopy image of an adult mouse’s hippocampus by Sandra Dieni of the Institute of Anatomy and Cell Biology at Albert-Ludwigs University in Germany, reactive astroglia (star-shaped cells that support neurons in the brain, here colored pale yellow) have proliferated and enlarged in response to neuronal activity over time.