It is well established that the hippocampus and perirhinal cortex (PrC) encode associative and item representations, respectively. However, less is known about how item and associative memories are consolidated. We used high-resolution fMRI in humans to measure how functional connectivity between these distinct medial temporal lobe regions with the ventral tegmental area (VTA) after a paired associate encoding task is related to both immediate and 24 h item and associative memory performance. We found that the strength of post-encoding functional connectivity between the VTA and CA1 selectively correlated with long-term associative memory, despite subjects actively engaging in an unrelated task during this period. Conversely, VTA–PrC functional connectivity during the same period correlated with long-term item memory. Critically, connectivity between VTA and these MTL regions were only related to memory tested at a 24 h delay, implicating midbrain connectivity in the consolidation of distinct forms of memory.
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