Resistance to forgetting associated with hippocampus-mediated reactivation during new learning


One of the reasons why we forget past experiences is because we acquire new memories in the interim. Although the hippocampus is thought to be important for acquiring and retaining memories, there is little evidence linking neural operations during new learning to the forgetting (or remembering) of earlier events. We found that, during the encoding of new memories, responses in the human hippocampus are predictive of the retention of memories for previously experienced, overlapping events. This brain-behavior relationship is evident in neural responses to individual events and in differences across individuals. We found that the hippocampus accomplishes this function by reactivating older memories as new memories are formed; in this case, reactivating neural responses that represented monetary rewards associated with older memories. These data reveal a fundamental mechanism by which the hippocampus tempers the forgetting of older memories as newer memories are acquired.

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Figure 1: Experimental design and behavioral results.
Figure 2: Relationship between AC encoding and AB forgetting.
Figure 3: Hippocampal responses during encoding and susceptibility to retroactive interference.
Figure 4: ROI analysis of reward-sensitive regions, as defined from independent reward-localizer task.


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We thank B. Knutson, J. Cooper, G. Samanez-Larkin and S. McClure for helpful advice and discussions. This work was supported by the National Institute of Mental Health (5R01-MH080309) and the Alfred P. Sloan Foundation.

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B.A.K. and A.D.W. designed the experiments and prepared the manuscript. B.A.K., A.T.S. and S.D. contributed to data collection and analysis.

Corresponding authors

Correspondence to Brice A Kuhl or Anthony D Wagner.

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The authors declare no competing financial interests.

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Supplementary Figures 1–5, Supplementary Tables 1–14 and Supplementary Results (PDF 5020 kb)

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Kuhl, B., Shah, A., DuBrow, S. et al. Resistance to forgetting associated with hippocampus-mediated reactivation during new learning. Nat Neurosci 13, 501–506 (2010).

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