Specifying the role of the ventromedial prefrontal cortex in memory formation

Recent neuroimaging research suggests that the ventromedial prefrontal cortex (vmPFC) plays an important role for successful memory formation that takes place in the context of activated prior knowledge. These findings led to the notion that the vmPFC integrates new information into existing knowledge structures. However, a considerable number of neuroimaging studies that have investigated memory formation in the context of prior knowledge have not found vmPFC involvement. To resolve this inconsistency, we propose a distinction between knowledge-relevance (the degree to which new information can be linked to prior knowledge) and knowledge-congruency (the perceived match between prior knowledge and the to-be-encoded information). We hypothesized that the vmPFC contributes to successful memory formation only when perceived knowledge-congruency is high, independent of knowledge-relevance. We tested this hypothesis in a design that varied both congruency and relevance during memory encoding, which was performed in the MR scanner. As predicted, the results showed that vmPFC contributions to memory formation vary as a function of knowledge-congruency, but not as a function of knowledge-relevance. Our finding contributes to elucidating the seemingly inconsistent findings in the literature and helps to specify the role of the vmPFC in memory formation.