Autobiographically Significant Concepts: More Episodic than Semantic in Nature? An Electrophysiological Investigation of Overlapping Types of Memory

Abstract

A common assertion is that semantic memory emerges from episodic memory, shedding the distinctive contexts associated with episodes over time and/or repeated instances. Some semantic concepts, however, may retain their episodic origins or acquire episodic information during life experiences. The current study examined this hypothesis by investigating the ERP correlates of autobiographically significant (AS) concepts, that is, semantic concepts that are associated with vivid episodic memories. We inferred the contribution of semantic and episodic memory to AS concepts using the amplitudes of the N400 and late positive component, respectively. We compared famous names that easily brought to mind episodic memories (high AS names) against equally famous names that did not bring such recollections to mind (low AS names) on a semantic task (fame judgment) and an episodic task (recognition memory). Compared with low AS names, high AS names were associated with increased amplitude of the late positive component in both tasks. Moreover, in the recognition task, this effect of AS was highly correlated with recognition confidence. In contrast, the N400 component did not differentiate the high versus low AS names but, instead, was related to the amount of general knowledge participants had regarding each name. These results suggest that semantic concepts high in AS, such as famous names, have an episodic component and are associated with similar brain processes to those that are engaged by episodic memory. Studying AS concepts may provide unique insights into how episodic and semantic memory interact.

Personal semantics: Is it distinct from episodic and semantic memory? An electrophysiological study of memory for autobiographical facts and repeated events in honor of Shlomo Bentin

“…showing that this ERP component can be evoked by autobiographical in addition to (nonpersonal) laboratory material. This was confirmed in a study by Renoult et al (2015), in which the LPC was found to be increased for famous names that were associated with autobiographical episodes by the participants. Importantly, results from this study also illustrate that this ERP component is sensitive to the most automatic aspects of episodic retrieval, as the presence of associated episodes was only assessed after the experiment, and was thus incidental to task performance.…”

“…Further studies are thus needed to specify how the neural correlates of memories of repeated events differ from those of unique events. As we note below, one possible factor to explain a certain inconsistency in the difference between unique and repeated events is that it is possible that some memories of repeated events evoked recollective experiences, while others do not (Renoult, et al, 2015) Three broad conceptualizations of personal semantics were proposed in our review : 1) that personal semantics could be a sub-domain of semantic memory, 2) that declarative memory could be organized according to a continuum of abstraction from abstract/acontextual to personal/contextual and 3) that PS, semantic and episodic memory could involve a different weighting of different component processes (see Cabeza & Moscovitch, 2013 on process-specific alliances). While the present results cannot be used to definitively decide between these views, a number of observations can be made.…”

“…A similar proportion was observed for patients with lesions restricted to the hippocampus (7 impaired out of 15). Certain autobiographical facts and memories of repeated events may be experience-near and bound to unique episodic memories (Renoult, et al, 2015;Westmacott, Black, Freedman, & Moscovitch, 2004;Westmacott & Moscovitch, 2003), while other may be more abstract and similar to general facts. One could thus argue that the observation that memories of autobiographical facts and repeated events were associated with intermediate modulations of N400 and LPC as compared to general facts and unique events, could be due to this heterogeneity.…”

“…Nonetheless, as self-relevant material could activate both personal semantics and episodic memory, modulations of both the N400 and the LPC would be expected. Even though sensitivity of the LPC to episodic autobiographical retrieval has been clearly established (Johnson et al, 2011;Renoult et al, 2015), modulation of the N400 to personal in addition to general semantics still needs confirmation and could help clarify whether personal semantics is simply a subcomponent of semantic memory or involves partly distinct neural correlates .…”

Priming, not inhibition, of related concepts during future imagining

“…However, there is reason to believe that concepts with personal significance engage more than just the semantic memory system. Recent work suggests that these concepts may be more similar to episodic memory than general semantic memory (for a review, see Renoult, Davidson, Palombo, Moscovitch, & Levine, 2012), in that autobiographically significant concepts automatically activate related episodes in memory (Westmacott, Black, Freedman, & Moscovitch, 2004; Westmacott & Moscovitch, 2003) and evoke a neural signature more similar to episodic than semantic memory (Renoult et al, 2015, 2016). Thus, the current effects could be partly or entirely driven by episodic memory, with the names of familiar places activating related details of past episodes, including people who were there, in a relatively automatic (and potentially subconscious) manner.…”