Poster E85, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Overlap between fMRI novelty and recollection effects
Marianne de Chastelaine1, Julia Mattson1, Tracy Wang1, Brian Donely1, Michael Rugg1; 1The University of Texas at Dallas, USA
fMRI findings suggest that familiarity- and recollection-based memory judgments have distinct neural correlates. Most studies investigating fMRI correlates of familiarity have focused on contrasts assessing where greater familiarity is associated with greater BOLD activity. A smaller number of studies have identified regions where BOLD activity is lower for familiar than for novel items (‘novelty effects’). In a large cohort of participants (n = 136), we examined the overlap between fMRI correlates of recollection, familiarity, and novelty. Participants were scanned during an associative recognition test following a study phase in which word pairs were visually presented in the context of an elaborative encoding task. Test items comprised studied, rearranged (items studied on different trials) and new pairs. Familiarity effects were operationalized as greater activity for studied test pairs incorrectly identified as ‘rearranged’ than for correctly rejected new pairs. The reverse contrast was employed to identify ‘novelty’ effects. Recollection effects were identified by greater activity for correctly identified studied test pairs than for those incorrectly identified as rearranged. There was almost no overlap between fMRI recollection and familiarity effects, but there was extensive overlap between novelty and recollection effects, including in the anterior hippocampus and perirhinal cortex. Across participants, the magnitude of the MTL novelty effects correlated with behavioral measures of both familiarity and recollection. By contrast, hippocampal recollection effects correlated only with recollection performance. The findings suggest that fMRI novelty effects in the MTL reflect a generic memory signal, while recollection effects reflect a memory signal selective for recollection-based judgments.
Topic Area: LONG-TERM MEMORY: Episodic