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Hippocampal and cortical mechanisms at retrieval explain variability in episodic remembering in older adults
Journal article   Open access   Peer reviewed

Hippocampal and cortical mechanisms at retrieval explain variability in episodic remembering in older adults

Alexandra N Trelle, Valerie A Carr, Scott A Guerin, Monica K Thieu, Manasi Jayakumar, Wanjia Guo, Ayesha Nadiadwala, Nicole K Corso, Madison P Hunt, Celia P Litovsky, …
eLife, Vol.9, e55335
05/29/2020
DOI: 10.7554/eLife.55335
PMCID: PMC7259949
PMID: 32469308
url
https://doi.org/10.7554/eLife.55335View
Published (Version of record) Open Access

Abstract

Age-related episodic memory decline is characterized by striking heterogeneity across individuals. Hippocampal pattern completion is a fundamental process supporting episodic memory. Yet, the degree to which this mechanism is impaired with age, and contributes to variability in episodic memory, remains unclear. We combine univariate and multivariate analyses of fMRI data from a large cohort of cognitively normal older adults (N=100) to measure hippocampal activity and cortical reinstatement during retrieval of trial-unique associations. Trial-wise analyses revealed that (a) hippocampal activity scaled with reinstatement strength, (b) cortical reinstatement partially mediated the relationship between hippocampal activity and associative retrieval, (c) older age weakened cortical reinstatement and its relationship to memory behaviour. Moreover, individual differences in the strength of hippocampal activity and cortical reinstatement explained unique variance in performance across multiple assays of episodic memory. These results indicate that fMRI indices of hippocampal pattern completion explain within- and across-individual memory variability in older adults.
Magnetic Resonance Imaging Humans Middle Aged Memory, Episodic Male Cerebral Cortex - diagnostic imaging Hippocampus - diagnostic imaging Aging - physiology Mental Recall - physiology Aged, 80 and over Cerebral Cortex - physiology Female Aged Hippocampus - physiology

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