Medial temporal lobe activity can distinguish between old and new stimuli independently of overt behavioral choice.

Full Abstract

We collected fMRI data and confidence ratings as participants performed a recognition memory task that intermixed recently studied words and new (non-studied) words. We first replicated a typical finding from such studies; namely, increasing activity in medial temporal lobe structures with increasing confidence in the old/new decision. Because there are greater proportions of old items at higher confidence levels, such activity could be related to the confidence ratings or to whether items are old or new. When activity associated with old and new items was analyzed separately, we found that activity in the hippocampus bilaterally, as well as in anterior parahippocampal gyrus, was associated with the actual old/new status of the items rather than to which items participants believed to be old. Accordingly, activity in the medial temporal lobe can be modulated by the old/new status of stimuli and does not always track the behavioral response.

Author information

Author/s: Kirwan, C Brock (CB); Shrager, Yael (Y); Squire, Larry R (LR);

Affiliation: Department of Psychiatry, University of California at San Diego, La Jolla, CA 92093, USA.

Grants: 24600 (Agency:PHS HHS) ; R01 MH024600-36 (Agency:NIMH NIH HHS) ; T32MH20002 (Agency:NIMH NIH HHS) ; (Agency:Howard Hughes Medical Institute)

Journal and publication information

Publication Type: Clinical Trial; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A), published in United States. (Language: eng)

Reference: 2009-Aug; vol 106 (issue 34) : pp 14617-21

Dates: Created 2009/08/26; Completed 2009/09/28;

PMID: 19706549, status: MEDLINE (last retrieval date: 9/28/2009, IMS Date: )

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