26 July 2013
Vol 341, Issue 6144

About The Cover

Cover image expansion

COVER Immunostained fluorescence microscopy image of memory engram–bearing cells (red) in the dentate gyrus of a mouse hippocampus (image width: 1.5 millimeters). These cells were genetically tricked to express the protein channelrhodopsin-2 during memory formation, thus becoming responsive to light stimulation. When the cells were activated by light, the mice simultaneously associated a genuine memory with an undesirable event (a foot shock) to create a new but false memory. See page 387. Image: Xu Liu and Steve Ramirez