, 2009). The hairpin maze enabled us to determine whether representations in PPC and MEC were expressed synchronously or independently since it elicited spatially discrete firing fields from cells in both areas. We hypothesized that running the rats in hairpin mazes in two different rooms would drive grid cells to realign their firing fields (Fyhn et al., 2007 and Hafting et al., 2005) and allow us to observe whether such a realignment extended to representations

in PPC as well (Figure 6A). We ran the rats in hairpin mazes in two different rooms and found that grid cells realigned their firing fields completely in the different rooms, selleck chemical while parietal cells maintained the same preferences (Figure 6A). Statistical analysis confirmed that the firing field locations of PPC cells were more correlated than those of grid cells in different rooms (mean r value of 0.47 for PPC cells versus 0.03 for grids cells; D = 0.54, find more p < 0.001, K-S test; Figure 6B), while cells from both areas expressed comparable stability

in the same-room condition (mean r value of 0.56 for PPC cells versus 0.59 for grid cells; D = 0.11, p > 0.3; Figure 6B). Thus, representations in PPC were unchanged despite a complete realignment of firing fields in MEC. The observation that cells in PPC maintain their firing preferences in different recording rooms does not mean that representations in PPC are disconnected from the Tryptophan synthase environment. Electrophysiological studies have shown that locomotor responses of PPC cells vary depending on where in a maze or along which route an action was made (McNaughton et al., 1989, Chen et al., 1994a, Nitz,

2006 and Sato et al., 2006). It has never been determined, however, whether PPC cells respond primarily to the structure of the animal’s behavior in the task, or to the structure of the environment in which the recording was made. To address this we compared firing properties of PPC cells in the hairpin maze and open field in several ways. First, we generated self-motion and acceleration rate maps from recordings in the hairpin maze and found that a large fraction of PPC cells showed tuning to discrete modes of movement and that these representations were stable across west- and eastbound traversals (Figures S6–S8). The independence of running direction implies that the firing was independent of major sensory cues in this task. At the same time, we found that running in the hairpin task expanded the tuning of PPC cells to path segments traversed more than 1 s before and after the animals’ actual position (Figure S9). This may reflect the stereotypic sequential ordering of the animal’s behavior in this particular task, suggesting that the firing may have been dependent on the particular actions performed by the animal.