Brain Activity and Functional Coupling Changes Associated with Self-Reference Effect during Both Encoding and Retrieval

Nastassja Morel,Gaël Chételat,Florence Mézenge,Brigitte Landeau,Pascale Piolino,Nicolas Villain,Malo Gaubert,Francis Eustache,Géraldine Rauchs,Béatrice Desgranges,Michelle Hampson

doi:10.1371/journal.pone.0090488

Abstract

Information that is processed with reference to oneself, i.e. Self-Referential Processing (SRP), is generally associated with better remembering compared to information processed in a condition not related to oneself. This positive effect of the self on subsequent memory performance is called as Self-Reference Effect (SRE). The neural basis of SRE is still poorly understood. The main goal of the present work was thus to highlight brain changes associated with SRE in terms of activity and functional coupling and during both encoding and retrieval so as to assess the relative contribution of both processes to SRE. For this purpose, we used an fMRI event-related self-referential paradigm in 30 healthy young subjects and measured brain activity during both encoding and retrieval of self-relevant information compared to a semantic control condition. We found that SRE was associated with brain changes during the encoding phase only, including both greater activity in the medial prefrontal cortex and hippocampus, and greater functional coupling between these brain regions and the posterior cingulate cortex. These findings highlight the contribution of brain regions involved in both SRP and episodic memory and the relevance of the communication between these regions during the encoding process as the neural substrates of SRE. This is consistent with the idea that SRE reflects a positive effect of the reactivation of self-related memories on the encoding of new information in episodic memory.

Highlights

One’s sense of self fundamentally depends on self-knowledge and memories of one’s past experiences [1,2,3]
These studies consistently reported the involvement of cortical midline structures such as the medial prefrontal cortex (MPFC) extending to the anterior cingulate cortex (ACC) and the posterior cingulate cortex (PCC) [5,6,7,8,9]
While other regions are implicated in specific aspects of the self, such as temporoparietal areas in agency, cortical midline structures are thought to be involved in the ‘‘core self’’ in that they are crucial to the processing of selfreferential stimuli even if they are differentially involved in the different self-related processes

Summary

Introduction

One’s sense of self fundamentally depends on self-knowledge and memories of one’s past experiences [1,2,3]. SRP generally consists in linking implicitly or explicitly the information to-be-processed with pre-existent semantic self-knowledge and autobiographical memories (for review, [4]). Numerous neuroimaging studies have been conducted to assess the underlying mechanisms of SRP, for example by asking participants to judge whether a trait adjective describes their personality. These studies consistently reported the involvement of cortical midline structures such as the medial prefrontal cortex (MPFC) extending to the anterior cingulate cortex (ACC) and the posterior cingulate cortex (PCC) [5,6,7,8,9]. The MPFC is considered as a key-component of the Self-Memory System [10] as it is activated regardless of the level of abstraction of information related to the Self (from general self-knowledge to specific autobiographical memories) while other structures would tend to be involved in specific conditions e.g. in relation to the recollection of autobiographical memories for the hippocampus and the posterior areas [11,12,13,14]

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Conclusion