Delay-dependent contributions of medial temporal lobe regions to episodic memory retrieval

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Abstract

The medial temporal lobes play an important role in episodic memory, but over time, hippocampal contributions to retrieval may be diminished. However, it is unclear whether such changes are related to the ability to retrieve contextual information, and whether they are common across all medial temporal regions. Here, we used functional neuroimaging to compare neural responses during immediate and delayed recognition. Results showed that recollection-related activity in the posterior hippocampus declined after a one-day delay. In contrast, activity was relatively stable in the anterior hippocampus and in neocortical areas. Multi-voxel pattern similarity analyses also revealed that anterior hippocampal patterns contained information about context during item recognition, and after a delay, context coding in this region was related to successful retention of context information. Together, these findings suggest that the anterior and posterior hippocampus have different contributions to memory over time and that neurobiological models of memory must account for these differences.

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Maureen Ritchey

Center for Neuroscience, University of California, Davis, Davis, United States

For correspondence
meritchey@ucdavis.edu

Competing interests
The authors declare that no competing interests exist.
Maria E Montchal

Center for Neuroscience, University of California, Davis, Davis, United States

Competing interests
The authors declare that no competing interests exist.
Andrew P Yonelinas

Department of Psychology, University of California, Davis, Davis, United States

Competing interests
The authors declare that no competing interests exist.
Charan Ranganath

Center for Neuroscience, University of California, Davis, Davis, United States

Competing interests
The authors declare that no competing interests exist.

Ethics

Human subjects: The study was approved by the Institutional Review Board at the University of California, Davis (protocol #238604). Written informed consent was obtained from each participant before the experiment, including consent to publish anonymized results.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.