The default mode network contributes to familiarity as well as recollection: Evidence from graded familiarity paradigms

Description: Recognition memory is widely thought to depend on two dissociable processes, recollection and familiarity. fMRI studies have shown that the recollection > familiarity contrast is dominated by the Default Mode Network (DMN), whereas the familiarity > novelty contrast instead implicates the Fronto-Parietal Control Network (FPCN)—a dissociation commonly interpreted as evidence that the DMN is selective for recollection. However, these contrasts cannot establish whether the DMN also contributes to familiarity; they show only that it is engaged more strongly by recollection than familiarity To test whether DMN engagement increases with familiarity strength, the present study used activation likelihood estimation to meta-analyze nine fMRI studies employing graded familiarity paradigms, in which familiarity strength was modeled parametrically across multiple confidence levels. Familiarity-strength effects converged predominantly within the DMN (63.6% of significant voxels), followed by the FPCN (33.0%), indicating that the DMN also contributes to familiarity-based recognition. Re-analysis of a prior meta-analysis of the recollection > novelty contrast revealed a similar network profile (DMN = 66.4%; FPCN = 25.0%). Taken together, these findings indicate that recollection and familiarity recruit largely the same large-scale networks, differing primarily in the relative degree of DMN and FPCN engagement rather than in which networks are involved—supporting a graded rather than dichotomous view of the neural architecture underlying recognition memory.