Because the animal had to forage over the entire arena to retrieve the pellet(s), good sampling of all locations was obtained during recordings

Because the animal had to forage over the entire arena to retrieve the pellet(s), good sampling of all locations was obtained during recordings. dorsal hippocampal place cells encode space independently of its associated value despite the effect of that value on spatial behavior. Our findings are consistent with a model of place cells in which they provide a spontaneously constructed value-free spatial representation rather than encoding other navigationally relevant but nonspatial information. SIGNIFICANCE STATEMENT We investigated whether hippocampal place cells, which compute a self-localization signal, also encode the relative value of places, which is essential information for optimal navigation. When choosing between two spatial goals of different value, rats favored the higher-value goal. We saw out-of-field goal firing in place cells, replicating previous observations that this cells are influenced by the goal, but their activity was not modulated by the value of these goals. Our results suggest that place cells do not encode all of the navigationally relevant aspects of a place, but instead form a value-free AST2818 mesylate map that links to such aspects in other parts of the brain. in the hippocampus. One such study found no evidence of hippocampal encoding of goal value (Tabuchi et al., 2003), but the spatial demands of this task were low. Others have suggested that place cells may encode reward probability, action value, or reward expectation (H Lee et al., 2012; Lee et al., 2017; Tryon et al., 2017) CEACAM5 in linear mazes with no need for localizing a hidden goal. The amount of reward available at a goal seems to affect some hippocampal phenomena such as sharp-wave ripples in the local field potential (Singer and Frank, 2009) or patterns of sequential place cell activation (replay; Ambrose et al., 2016), but these events happen at the time of reward consumption and might reflect a reward-related feedback signal rather than a representation of goal value. Therefore, the question of whether place cells encode the value of spatial goals is still open. To address this question, we modified a task we have previously used to investigate hippocampal AST2818 mesylate AST2818 mesylate goal coding (Hok et al., 2007a). The continuous navigation task (adapted from Rossier et al., 2000) requires animals to navigate to an unmarked location in an open field and wait there for AST2818 mesylate a short duration (2 s), after which an overhead dispenser releases a food pellet that the animal has to search for. This task dissociates goal location from reward consumption, and allows recording of place fields because the animal covers the whole environment during its search for the reward. We previously found that CA1 place cells with place fields located away from the goal fire spikes when the animal waits in the goal zone (Hok et al., 2007a), suggesting possible goal encoding. The task that we designed has two simultaneous goals that could provide different amounts of food, thus adding a value-based decision-making component to this spatial task. We found that rats were able to locate the two goals and preferentially navigate to the higher-value goal, indicating behavioral sensitivity to this parameter. However, we did not observe AST2818 mesylate any place field overrepresentation of the goals and saw no evidence of consistent goal value coding by place cells. We conclude that place cells do not encode the value.