Hippocampal differentiation of competing memories predicts the precision of preparatory coding in visual cortex.

Many memories contain overlapping features, causing them to compete. How do we overcome memory competition to guide attention in complex environments? We hypothesized that hippocampal differentiation of competing memories would influence the precision of preparatory coding in visual cortex during memory-guided attention. We leveraged fMRI-based pattern similarity, receptive field modeling, and eye tracking to test this hypothesis in humans performing a memory-dependent visual search task. In the hippocampus, differentiation of competing memories predicted the precision of memory-guided eye movements. In visual cortex, preparatory coding of remembered target locations predicted search successes, whereas preparatory coding of competing locations predicted search failures due to interference. These effects were linked: stronger hippocampal memory differentiation was associated with lower competitor activation in visual cortex, yielding more precise preparatory representations. These results reveal how attention succeeds despite memory competition, highlighting a role for memory systems in shaping the precision of preparatory coding in sensory cortex.