Opposing mechanisms support the voluntary forgetting of unwanted memories.
Reminders of the past can trigger the recollection of events that one would rather forget. Here, using fMRI, we demonstrate two distinct neural mechanisms that foster the intentional forgetting of such unwanted memories. Both mechanisms impair long-term retention by limiting momentary awareness of the memories, yet they operate in opposite ways. One mechanism, direct suppression, disengages episodic retrieval through the systemic inhibition of hippocampal processing that originates from right dorsolateral prefrontal cortex (PFC). The opposite mechanism, thought substitution, instead engages retrieval processes to occupy the limited focus of awareness with a substitute memory. It is mediated by interactions between left caudal and midventrolateral PFC that support the selective retrieval of substitutes in the context of prepotent, unwanted memories. These findings suggest that we are not at the mercy of passive forgetting; rather, our memories can be shaped by two opposite mechanisms of mnemonic control.
MRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, UK. roland.benoit@mrc-cbu.cam.ac.uk
Roland G
RG
Benoit
Michael C
MC
Anderson
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001499:Bayes Theorem; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006624:Hippocampus / Q000098:blood supply / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D033182:Intention; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D011939:Mental Recall; D008959:Models, Neurological; D009434:Neural Pathways / Q000098:blood supply / Q000502:physiology; D009483:Neuropsychological Tests; D017711:Nonlinear Dynamics; D010100:Oxygen / Q000097:blood; D017397:Prefrontal Cortex / Q000098:blood supply / Q000502:physiology*; D012094:Repression, Psychology; D012153:Retention, Psychology; D055815:Young Adult
D010100:Oxygen