Subicular plateaus signal reward locations during goal-directed behavior.

Abstract

The hippocampus is essential for spatial learning, yet how its principal output structure, the subiculum, encodes behaviorally relevant information during navigation remains poorly understood. Because subicular neurons exhibit prominent burst firing, understanding how this bursting arises during behavior is critical. Using in vivo whole-cell recordings from dorsal subiculum neurons in head-fixed mice performing goal-directed navigation, we show that many bursts arise from plateau events. Plateaus were reduced by NMDA receptor blockade, indicating a dependence on synaptic input. Organizing plateaus by membrane potential preceding their onset revealed distinct behavioral associations. Plateaus initiated from hyperpolarized potentials clustered preferentially near reward locations, whereas those initiated from more depolarized potentials were more spatially distributed. Reward-related clustering required a fixed, learned reward location and was dynamically rearranged while learning a new reward location in a familiar environment. Together, these findings identify subicular plateaus as a cellular substrate of hippocampal bursting output, organized by membrane potential state.