STRATEGY-DEPENDENT MANIFESTATION OF MEMORY RECALL UNDER INTERFERENCE

During memory-guided behavior, animals use experience to guide decisions beyond simple sensory–motor mappings. In natural environments, recall often involves competition between multiple relevant memories, leading to interference and behavioral variability, yet how this competition is resolved remains unclear. To address this, we used the 8-port maze (Morales.,2020), a high-throughput rodent spatial task designed to probe recall under uncertainty, in which the memory of multiple previously rewarded locations compete within the same session. A GLM-HMM allowed us to identify four distinct latent strategies: 2h memory-based, 24h memory-based, memory avoidance, and lapse (reward foraging) that are manifested during recall behavior. These strategies dynamically fluctuated within and across sessions and accounted for trial-by-trial behavioral variability. Crucially, we found a distance-dependent effect in the competition between 2h and 24h memory strategies, showing that when 2h memory fails to guide behavior, alternative strategies are selected rather than reduced expression of that memory in behavior. To causally test the interpretation of our results, we perturbed long-term memory through anti-NMDAR antibody infusion, which led to decrease in memory consolidation and a change of strategy usage characterized by dominance of short-term recall (2h), and reduced expression of alternative strategies. Building on this behavioral paradigm, ongoing calcium imaging analyses aim to investigate how these latent recall strategies are reflected in hippocampal neural population dynamics. Our work reframes memory recall as a dynamic, state-dependent process, in which interference and variability arise from flexible strategy selection and could be the first demonstration of strategy neuronal encoding in mouse hippocampus.