Understanding metamemory: neural correlates of the cognitive process and subjective level of confidence in recognition memory.

An essential feature of human memory is the capacity to assess confidence in one's own memory performance, but the neural mechanisms underlying the process of determining confidence in memory performance have not yet been isolated. Using functional magnetic resonance imaging, we examined both the process of confidence assessment and the subjective level of high or low confidence expressed during this process. The comparison of confidence assessment to recognition showed greater relative activation during confidence assessment in medial and lateral parietal regions, which typically deactivate during cognitive tasks, previously described as part of the "default network". Furthermore, comparisons of high versus low confidence judgments revealed modulation of neural activity in the hippocampus, cingulate and other limbic regions, previously described as the Circuit of Papez. Our findings suggest that activity in two distinct networks of brain regions contribute to the subjective experience of "knowing you know" through memory monitoring processes and signaling subjective confidence level for recognition memory.