Abstract
Memory can guide attention, improving our ability to quickly identify or detect visual stimuli in complex environments. However, many of our memories contain overlapping features, which can trigger them to compete in guiding behavior. How does the brain overcome memory competition to effectively guide visual attention? We designed a memory-guided attention task that required human participants to recall scene-location memories to predict the location of search targets (small visual distortions) on the following trial. Critically, all scenes had a visually similar, and therefore competing, scene that guided search to a different location. Analysis of eye movements confirmed that participants effectively used memory to improve visual search; search was more accurate on trials for which memory-based predictions were valid, compared to when they were invalid or when no memory was available. However, participants also made some eye movements to the competing location, suggesting that interference between memories was also present. Using fMRI, we tested the hypothesis that the hippocampus would differentiate competing memories, allowing visual cortex to anticipate the correct target location and guide precise eye movements. Hippocampal activity patterns for competing memories were less correlated than activity patterns for unrelated memories, and stronger hippocampal memory differentiation was related to better visual search. We then used a population receptive field model fit to independent data to evaluate spatially-selective activity in visual cortex and its relationship to subsequent eye movements during search. Anticipatory activation of the target location in visual cortex predicted accurate search performance on the next trial, whereas activation of the competing location predicted poor performance. Ongoing analyses aim to directly relate memory differentiation in the hippocampus to spatial anticipation in visual cortex. These results suggest that the hippocampus may resolve competition between similar memories, enabling visual cortex to anticipate task-relevant locations to prepare efficient behavior.