A brief outline of this process can be seen in Figure 7. only one route), whereas only two cells (4.2%) showed goal-dependent firing (firing similarly on both routes). In addition, route-dependent place cells over-represented the less discriminable routes, and place cells in Madecassic acid general over-represented the start location. These results indicate that place cell firing on overlapping routes reflects the animals route, not its goals, and that this firing may aid spatial discrimination. DOI: http://dx.doi.org/10.7554/eLife.15986.001 = 0.32; Physique 2A solid line). The time the rats took to complete each trial once they had located the rewarded goal in a block of trials also decreased significantly across sessions (= 0.38; Physique 2B solid line). In contrast, neither the number of errors per session (= 0.70). Across all sessions, the rats averaged 9.08?s (S.D. = 6.19?s) to travel from the start box to Madecassic acid the end of the maze on trials before they had identified the goal box which contained reward. Once the rewarded goal box had been visited, travel time on later trials in that block decreased to 5.38?s (S.D. = 3.48?s). Routes to the same goal were more difficult to distinguish than routes to different goals During training the animals made a greater number of errors around the trials when Routes 2 or 3 3 to the Centre Goal Box were rewarded than on trials when the outer routes (Routes 1 or 4) to the Left and Right Goal Boxes, respectively, were rewarded (= 0.21; Physique 2D). We sought to define the nature of the errors which rats made after finding the location of the food reward in each block. An error where the rat took Route 1 to the Left Madecassic acid Goal Box when Route 2 to the Centre Goal Box was rewarded can be interpreted as a similar form of navigation error as taking Route 2 to the Centre Goal Box when Route 1 to the Left Goal Box was rewarded. Both results may reflect an inability to discriminate between those two reward locations or routes. Figure 2E shows the distribution of post-reward errors when grouped into the six possible pairs of these confusion errors. From this physique it is clear that this rats made more errors between the two routes to the same goal (Routes 2 and 3 to the Centre Goal) as opposed to any other route pairs (= Madecassic acid 0.52). Post-hoc multiple comparison tests confirmed Routes 2 and 3 were confused more than any other route pair (p<0.05 in all cases, with Sidak correction). Single unit activity Place cells over-represent the start area of the Rabbit Polyclonal to FAKD1 maze To test whether place cell activity encodes routes or goals, the trained rats were implanted with tetrodes targeting the CA1 cell layer of the hippocampus. In total, we recorded 377 place cells that were active on the maze from eight rats. We first analysed the distribution of place cell activity within the maze. The maze was divided into 14 sectors and place cells were categorised as being active in a given sector (defined as mean firing rate >1?Hz in that sector when the rat traversed one of the four trajectories) or not. Place cells were more likely to have a place field in the initial areas of the maze (e.g., the start box, central stem and first choice point) than in later ones (Physique 3A; see also Ainge et al., 2007). Consistent with this, there was a significant unfavorable correlation between distance of the sector from the start box and the number of recorded place cells that were active in that sector (= 48) = 15.96, p<0.004, Fischers exact test, Figure 5A). Open in a separate.