Changing the shape of an enclosure from a cylinder to a square can cause hippocampal place cells to remap the environment (Muller & Kubie 1987; Quirk et al. 1992). Lever, Cacucci, Burgess, & O'Keefe (SFN Abstract 1999) reported that remapping occurred primarily when the cylinder and square occupied different locations in the environment. We recorded place cells from ensembles in CA1, CA3, and dentate gyrus in 7 rats foraging in a gray cylinder or square, each with a white cue card. When the cylinder and square were in identical locations in the room (4 rats), and the rat was returned to a holding platform between sessions, 27/40 cells maintained the same place fields in both enclosures, 7 cells remapped, and 6 cells remapped partially (either maintaining the same field at a weaker strength or by remapping one subfield but maintaining another). When the rat was moved directly from the cylinder to an adjacently located square (5 rats), only 7/54 cells maintained the same field, 37 cells remapped, and 10 cell...