Episodic memory and self-reference via semantic autobiographical memory: insights from an fMRI study in younger and older adults.

Sandrine Kalenzaga,Catherine Oppenheim,Marion Delhommeau,Penelope Martinelli,Marie-Odile Krebs,Stã©Phanie Lion,Pascale Piolino,Marco Sperduti,Adã¨Le Anssens,Anne-Dominique Devauchelle,Thierry Gallarda,Isabelle Amado

doi:10.3389/fnbeh.2014.00449

Abstract

Self-referential processing relies mainly on the medial prefrontal cortex (MPFC) and enhances memory encoding (i.e., Self-Reference Effect, SRE) as it improves the accuracy and richness of remembering in both young and older adults. However, studies on age-related changes in the neural correlates of the SRE on the subjective (i.e., autonoetic consciousness) and the objective (i.e., source memory) qualitative features of episodic memory are lacking. In the present fMRI study, we compared the effects of a self-related (semantic autobiographical memory task) and a non self-related (general semantic memory task) encoding condition on subsequent episodic memory retrieval. We investigated encoding-related activity during each condition in two groups of 19 younger and 16 older adults. Behaviorally, the SRE improved subjective memory performance in both groups but objective memory only in young adults. At the neural level, a direct comparison between self-related and non self-related conditions revealed that SRE mainly activated the cortical midline system, especially the MPFC, in both groups. Additionally, in older adults and regardless of the condition, greater activity was found in a fronto-parietal network. Overall, correlations were noted between source memory performance and activity in the MPFC (irrespective of age) and visual areas (mediated by age). Thus, the present findings expand evidence of the role of the MPFC in self-referential processing in the context of source memory benefit in both young and older adults using incidental encoding via semantic autobiographical memory. However, our finding suggests that its role is less effective in aging.

Highlights

Healthy aging is associated with significant changes in episodic memory, defined as the memory of specific episodes
Source memory may rely on strategic processes (Fletcher and Henson, 2001; Dobbins and Han, 2006) that are deficient in older adults (Johnson et al, 1993) it has been proposed that one way to reduce age-related deficits in source monitoring is to give encoding instructions that favor the link between an item and its context, for example by asking participants to decide to what extent an item suits its encoding context (Hashtroudi et al, 1994; Glisky et al, 2001; Naveh-Benjamin et al, 2007; Glisky and Kong, 2008)
Our study aimed to explore the neural correlates of the Self-Reference Effect” (SRE) via autobiographical memory and their age-related changes

Summary

Introduction

Healthy aging is associated with significant changes in episodic memory, defined as the memory of specific episodes. Older adults have some difficulties in determining the context or experimental encoding conditions of a previously encountered item (Johnson et al, 1993 for a review) These age-related impairments in source memory are pronounced when encoding contexts are very similar (Hashtroudi et al, 1989; Henkel et al, 1998). Source memory may rely on strategic processes (Fletcher and Henson, 2001; Dobbins and Han, 2006) that are deficient in older adults (Johnson et al, 1993) it has been proposed that one way to reduce age-related deficits in source monitoring is to give encoding instructions that favor the link between an item and its context, for example by asking participants to decide to what extent an item suits its encoding context (Hashtroudi et al, 1994; Glisky et al, 2001; Naveh-Benjamin et al, 2007; Glisky and Kong, 2008).

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