Dissociation between the neural correlates of recollection and familiarity in the striatum and hippocampus: Across-study convergence

In tests of recognition memory, neural activity in the striatum has consistently been reported to differ according to the study status of the test item. A full understanding of the functional significance of striatal 'retrieval success' effects is impeded by a paucity of evidence concerning whether the effects differ according to the nature of the memory signal supporting the recognition judgment (recollection vs. familiarity). Here, we address this issue through an analysis of retrieval-related striatal activity in three independent fMRI studies (total N = 88). Recollection and familiarity were operationalized in a different way in each study, allowing the identification of test-independent, generic recollection- and familiarity-related effects. While activity in a bilateral dorsal striatal region, mainly encompassing the caudate nucleus, was enhanced equally by recollected and 'familiar only' test items, activity in bilateral ventral striatum and adjacent subgenual frontal cortex was enhanced only in response to items that elicited successful recollection. By contrast, relative to familiar items, activity in anterior hippo campus was enhanced for both recollected and novel test items. Thus, recollection- and familiarity-driven recognition memory judgments are associated with anatomically distinct patterns of retrieval-related striatal activity, and these patterns are at least partially independent of recollection and novelty effects in the hippocampus.