Top-down modulation of hippocampal encoding activity as measured by high-resolution functional MRI

Valerie A. Carr, Stephen A. Engel, Barbara J. Knowlton

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Memory formation is known to be critically dependent upon the medial temporal lobe (MTL). Despite this well-characterized role, it remains unclear whether and how MTL encoding processes are affected by top-down goal states. Here, we examined the manner in which task demands at encoding affect MTL activity and its relation to subsequent memory performance. Participants were scanned using high-resolution neuroimaging of the MTL while engaging in two incidental encoding tasks: one that directed participants' attention to stimulus distinctiveness, and the other requiring evaluation of similarities across stimuli. We hypothesized that attending to distinctiveness would lead to the formation of more detailed memories and would more effectively engage the hippocampal circuit than attending to similarity. In line with our hypotheses, higher rates of subsequent recollection were observed for stimuli studied under the Distinctiveness than Similarity task. Critically, within the hippocampus, CA1 and the subiculum demonstrated an interaction between memory performance and task such that a significant subsequent memory effect was found only when task goals required attention to stimulus distinctiveness. To this end, robust engagement of the hippocampal circuit may underlie the observed behavioral benefits of attending to distinctiveness. Taken together, these findings advance understanding of the effects of top-down intentional information on successful memory formation across subregions of the MTL.

Original languageEnglish (US)
Pages (from-to)1829-1837
Number of pages9
Issue number10
StatePublished - Aug 2013

Bibliographical note

Funding Information:
This work was made possible by grants from the National Science Foundation (NSF BCS 0848246, awarded to BJK) , the National Institutes of Health (T32 MH15795, awarded to VAC) , Achievement Rewards for College Scientists (awarded to VAC) , and the University of California, Los Angeles (Dissertation Year Fellowship, awarded to VAC) . We thank Karen LaRocque and Serra Favila for providing helpful feedback regarding the manuscript.


  • Encoding
  • Functional MRI
  • Goal states
  • Hippocampus
  • Medial temporal lobe
  • Memory


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