Reduced Hippocampal-Cortical Connectivity During Memory Suppression Predicts the Ability to Forget Unwanted Memories

Abstract

The ability to suppress unwelcome memories is important for productivity and well-being. Successful memory suppression is associated with hippocampal deactivations and a concomitant disruption of this regions functionality. Much of the previous neuroimaging literature exploring such suppression-related hippocampal modulations has focused on the regions negative coupling with the prefrontal cortex. In contrast, task-based changes in functional connectivity between the hippocampus and other brain regions have remained relatively underexplored. Here, we utilize psychophysiological interactions and seed connectome-based predictive modeling (seed-CPM) to investigate the relationship between the hippocampus and the rest of the brain as 134 participants attempted to suppress unwanted memories during the Think/No-Think task. The results show that during retrieval suppression, the right hippocampus exhibited decreased functional connectivity with visual cortical areas (bilateral intracalcarine cortex, right cuneal cortex, left lingual gyrus, right supracalcarine cortex, right occipital pole), left nucleus accumbens and the brain-stem that predicted superior forgetting of unwanted memories on later memory tests. Validation tests verified that prediction performance was not an artifact of head motion or prediction method and that the negative features remained consistent across different brain parcellations. These findings suggest that systemic memory suppression involves more than the modulation of hippocampal activity--it alters functional connectivity patterns between the hippocampus and visual cortex, leading to successful forgetting.