Evidence for a Single Rather than a Triple Dissociation in the Medial Temporal Lobe: an fMRI Recognition Memory Replication Study

Common research practices in neuroimaging studies using functional magnetic resonance imaging may produce outcomes that are difficult to replicate. Results that cannot be replicated have contributed to a replication crisis in psychology, neuroscience, and other disciplines over the years. Here we replicate two previous papers in which the authors present two analysis paths for a dataset in which participants underwent fMRI while performing a recognition memory test for old and new words. Both studies found activation in the medial temporal lobe including the hippocampus, with the first demonstrating a distinction in activation corresponding to true and perceived oldness of stimuli and the second demonstrating that activation reflects the subjective experience of the participant. We replicated the behavioral and MRI acquisition parameters reported in the two target articles (Daselaar, Fleck, & Cabeza, 2006; Daselaar, Fleck, Prince, et al., 2006) with N=53 participants. We focused fMRI analyses on regions of interest reported in the target articles examining fMRI activation for differences corresponding with true and perceived oldness and those associated with the subjective memory experiences of recollection, familiarity, and novelty. Comparisons between true and perceived oldness revealed main effects not only for true, but also perceived oldness along with significant interaction effects. We replicate the findings of recollection and familiarity signals in the hippocampus and medial temporal lobe cortex, respectively, but failed to replicate a novelty signal in the anterior medial temporal lobe. These results remained when we analyzed only correct trials, indicating that the effects were not due to selectively averaging correct and incorrect trials. Taken together, our findings demonstrate that activation in the hippocampus corresponds to the subjective experience associated with correct recognition memory retrieval. Highlights We replicated the methods of two influential papers using fMRI to examine recognition memory. The hippocampus consistently signals the subjective experience of remembering but not the objective old/new status of stimuli. Hippocampal response was consistent with recollection while the medial temporal lobe (MTL) cortex response was consistent with familiarity. We did not observe any regions in the MTL that signaled novelty, indicating recognition memory does not involve a triple dissociation of recollection, familiarity, and novelty in the MTL.