Lifespan trends of autobiographical remembering: Episodicity and search for meaning

Traces of semantization - from episodic to semantic memory in a spiking cortical network model

Episodic memory is a recollection of past personal experiences associated with particular times and places. This kind of memory is commonly subject to loss of contextual information or" semantization", which gradually decouples the encoded memory items from their associated contexts while transforming them into semantic or gist-like representations. Novel extensions to the classical Remember/Know behavioral paradigm attribute the loss of episodicity to multiple exposures of an item in different contexts. Despite recent advancements explaining semantization at a behavioral level, the underlying neural mechanisms remain poorly understood. In this study, we suggest and evaluate a novel hypothesis proposing that Bayesian-Hebbian synaptic plasticity mechanisms might cause semantization of episodic memory. We implement a cortical spiking neural network model with a Bayesian-Hebbian learning rule called Bayesian Confidence Propagation Neural Network (BCPNN), which captures the semantization phenomenon and offers a mechanistic explanation for it. Encoding items across multiple contexts leads to item-context decoupling akin to semantization. We compare BCPNN plasticity with the more commonly used spike-timing dependent plasticity (STDP) learning rule in the same episodic memory task. Unlike BCPNN, STDP does not explain the decontextualization process. We further examine how selective plasticity modulation of isolated salient events may enhance preferential retention and resistance to semantization. Our model reproduces important features of episodicity on behavioral timescales under various biological constraints whilst also offering a novel neural and synaptic explanation for semantization, thereby casting new light on the interplay between episodic and semantic memory processes.Significance StatementRemembering single episodes is a fundamental attribute of cognition. Difficulties recollecting contextual information is a key sign of episodic memory loss or semantization. Behavioral studies demonstrate that semantization of episodic memory can occur rapidly, yet the neural mechanisms underlying this effect are insufficiently investigated. In line with recent behavioral findings, we show that multiple stimulus exposures in different contexts may advance item-context decoupling. We suggest a Bayesian-Hebbian synaptic plasticity hypothesis of memory semantization and further show that a transient modulation of plasticity during salient events may disrupt the decontextualization process by strengthening memory traces, and thus, enhancing preferential retention. The proposed cortical network-of-networks model thus bridges micro and mesoscale synaptic effects with network dynamics and behavior.

The Development of Identity Fusion

The fusion of personal and group identities can lead to self-sacrificial progroup behavior, from acts of charity to violent extremism. Two pathways to identity fusion-via shared biology and shared experiences-have been proposed. In this article, we elucidate a new developmental account of the origins and mechanisms of these two pathways to identity fusion from childhood to adulthood. Whereas fusion based on shared biology occurs from early childhood cued by phenotypic similarity, fusion based on episodic memories of shared experiences is not possible until midadolescence and relies on suitable bonding experiences (e.g., painful initiation rituals, emotionally intense team sports). The critical development that enables fusion based on shared experiences is autobiographical reasoning, which entails connecting one's past experiences to the present self. Autobiographical reasoning begins in adolescence, which may explain the flourishing of fusion in late adolescence and young adulthood relative to other life periods. Fusion via either pathway is linked to strong progroup behavior. We outline a program of empirical research on the development of identity fusion while addressing relevant methodological challenges. A developmental framework may help foster efforts to harness identity fusion for peaceful rather than violent forms of self-sacrifice for the group.

Beyond episodic remembering: elaborative retrieval of lifetime periods in young and older adults

Relative to young adults, cognitively normal older adults commonly generate more semantic details and fewer episodic details in their descriptions of unique life events. It remains unclear whether this reflects a specific change to episodic memory or a broader alteration to autobiographical narration. To explore age differences across different types of autobiographical narration, we created a lifetime period narrative task that involves describing extended events. For comparison, participants also described unique life events. All autobiographical narratives were scored for episodic, semantic, and other detail generation. Relative to young adults, older adults generated more detailed narratives for remote and recent lifetime periods, which was driven by their increased retrieval of personal and general semantic details. Older adults also generated more semantic details for unique life event narratives, along with reduced episodic detail. More broadly, in both groups lifetime period narratives were largely based on semantic details, whereas episodic details were more prominent in the descriptions of unique life events. These findings indicate that the elevated generation of semantic details associated with normal cognitive aging is reflected in multiple types of autobiographical narration. We suggest that lifetime period narration is a spared aspect of autobiographical memory among older adults.

Self-defining Memories in Normal Aging

BACKGROUND

Self-defining memories refer to events that are vivid, effectively intense, and include enduring concerns about oneself.

OBJECTIVE

We investigated the relationship between the production of these memories in normal aging and the ability to integrate new information into existing knowledge in memory (i.e., updating).

METHOD

Older participants were asked to perform an updating task as well as to retrieve autobiographical memories that were later analyzed for their self-defining relevance.

RESULTS

Analyses showed significant positive correlations between updating and the production of self-defining memories.

CONCLUSION

Updating our life story is an important psychological process,which enables us to refine and enrich our life story with new experiences, roles and/or challenges, and this ability seems to be related to the capacity to produce memories that draw on the pursuit of long-term goals, meaning making, emotional regulation, and/or activation of self-images (i.e., self-defining memories). These findings suggest that updating one's identity throughout life, at least in normal aging, may be related to the shaping and retrieval of self-defining memories, memories that lead to the creation of narrative scripts, which themselves serve as the ingredients for "chapters" across the lifespan.

Facing the Language-Memory Problem in the Study of Autobiographical Memory

This paper discusses the problem of the role of language in autobiographical memory, that is barely considered in studies on autobiographical memories and narratives. As a matter of fact, most of the current studies on autobiographical memory confounded memory and narrative together. The present paper focuses on two main issues. Firstly, it debates how narratives contribute to the construction of autobiographical memories through self-other communication. Secondly, it reflects on how language and communication should be manipulated in studies about autobiographical memory. This paper is made of three sections: the first section discusses the role of language, particularly in the form of narrative, as a social tool by which autobiographical memories can be organised in a life story; the second section examines previous methods of investigation used in the study of autobiographical memories; finally, the third section proposes different methodological alternatives to overcome the problems emerging from our analysis of literature.

When your face describes your memories: facial expressions during retrieval of autobiographical memories

Thanks to the current advances in the software analysis of facial expressions, there is a burgeoning interest in understanding emotional facial expressions observed during the retrieval of autobiographical memories. This review describes the research on facial expressions during autobiographical retrieval showing distinct emotional facial expressions according to the characteristics of retrieved memoires. More specifically, this research demonstrates that the retrieval of emotional memories can trigger corresponding emotional facial expressions (e.g. positive memories may trigger positive facial expressions). Also, this study demonstrates the variations of facial expressions according to specificity, self-relevance, or past versus future direction of memory construction. Besides linking research on facial expressions during autobiographical retrieval to cognitive and affective characteristics of autobiographical memory in general, this review positions this research within the broader context research on the physiologic characteristics of autobiographical retrieval. We also provide several perspectives for clinical studies to investigate facial expressions in populations with deficits in autobiographical memory (e.g. whether autobiographical overgenerality in neurologic and psychiatric populations may trigger few emotional facial expressions). In sum, this review paper demonstrates how the evaluation of facial expressions during autobiographical retrieval may help understand the functioning and dysfunctioning of autobiographical memory.

Positive facial expressions during retrieval of self-defining memories

In this study, we investigated, for the first time, facial expressions during the retrieval of Self-defining memories (i.e., those vivid and emotionally intense memories of enduring concerns or unresolved conflicts). Participants self-rated the emotional valence of their Self-defining memories and autobiographical retrieval was analyzed with a facial analysis software. This software (Facereader) synthesizes the facial expression information (i.e., cheek, lips, muscles, eyebrow muscles) to describe and categorize facial expressions (i.e., neutral, happy, sad, surprised, angry, scared, and disgusted facial expressions). We found that participants showed more emotional than neutral facial expressions during the retrieval of Self-defining memories. We also found that participants showed more positive than negative facial expressions during the retrieval of Self-defining memories. Interestingly, participants attributed positive valence to the retrieved memories. These findings are the first to demonstrate the consistency between facial expressions and the emotional subjective experience of Self-defining memories. These findings provide valuable physiological information about the emotional experience of the past.

Retrospective Reports of Negative Early Life Events Over a 4-Year Period: A Test of Measurement Invariance and Response Consistency

Objectives

The present study examined measurement invariance (i.e., construct validity), response consistency (i.e., test-retest reliability), and potential predictors of response consistency to the Health and Retirement Study (HRS) negative early life events questionnaire over two time points.

Method

The study was based on the HRS psychosocial questionnaire, which is a U.S. nationally representative survey of individuals older than 50 years and their spouses of any age. Overall, 4,541 individuals older than 50 years were eligible to complete the questionnaire and responded to all four negative early life events items in 2008 and 2012.

Results

Only partial invariance across the two time points was established (with three of the four loadings and two thresholds remaining constant over time). For 20% of the sample, at least one item was inconsistently reported across waves. A positive response to a negative early life event item in 2008 was the most consistent predictor of response inconsistency over time.

Conclusions

The measure of negative early life events has limited construct validity and test-retest reliability. Inconsistency is particularly high among those who had first endorsed an item. The use of this retrospective measure for the understanding of age and aging should be considered with caution. Panel surveys might consider probing about early life events repeatedly to better address inconsistencies over time.

Autobiographical Periods: A Review and Central Components of a Theory

Autobiographical periods refer to subjectively defined life periods with perceived beginnings and endings, including information about the people, places, activities, and objects associated with the period. Autobiographical periods are serial, parallel, and hierarchical and are associated with specific and categoric memories. Individuals construct autobiographical periods for the future and have knowledge of periods in other people's lives. The review shows that (a) autobiographical periods may facilitate the recall of specific memories; (b) specific memories from the beginning and end of autobiographical periods are more often recalled compared with specific memories from other time points; (c) autobiographical periods are used to place specific memories in time; (d) autobiographical periods play an important role in the construction of life stories; and (e) autobiographical periods are related to personality traits and well-being. The central components of a theory of autobiographical periods are outlined. Thinking of life as extended time periods is suggested to be the central process through which autobiographical periods are constructed. Sociocultural processes, experience, and goals are assumed to inform life period thinking, and thus the construction of autobiographical periods.

Contextualizing the self: the emergence of a biographical understanding in adolescence

In adolescence, remembering the personal past and understanding what kind of person one is intertwine to form a story of one's life as the most extant, informative, and flexible form of self-representation. In adolescence, the striving for self-coherence translates into a quest for global coherence of the life story. We suggest that contextualizing is a fifth means for creating global coherence in life narratives besides the cultural concept of biography, temporal, causal-motivational, and thematic coherence. We present three kinds of contextualizing in life narratives, the temporal macrostructure, sociohistorical contextualizing of one's life, and hierarchical and linear segmenting of the text and life. These three forms of contextualizing in life narratives by their authors are complemented by three forms of contextual influences on life narratives analyzed by researchers, namely the historical, personal, and communicative situation in which they are recounted. Contextualizing is exemplified by the life narrative of a young migrant.

The episodicity of verbal reports of personally significant autobiographical memories: vividness correlates with narrative text quality more than with detailedness or memory specificity

How can we tell from a memory report whether a memory is episodic or not? Vividness is required by many definitions, whereas detailedness, memory specificity, and narrative text type are competing definitions of episodicity used in research. We explored their correlations with vividness in personally significant autobiographical memories to provide evidence to support their relative claim to define episodic memories. In addition, we explored differences between different memory types and text types as well as between memories with different valences. We asked a lifespan sample (N = 168) of 8-, 12-, 16-, 20-, 40-, and 65-year-olds of both genders (N = 27, 29, 27, 27, 28, 30) to provide brief oral life narratives. These were segmented into thematic memory units. Detailedness of person, place, and time did not correlate with each other or either vividness, memory specificity, or narrative text type. Narrative text type, in contrast, correlated both with vividness and memory specificity, suggesting narrative text type as a good criterion of episodicity. Emotionality turned out to be an even better predictor of vividness. Also, differences between narrative, chronicle, and argument text types and between specific versus more extended and atemporal memories were explored as well as differences between positive, negative, ambivalent, neutral, contamination, and redemption memory reports. It is concluded that temporal sequentiality is a central characteristic of episodic autobiographical memories. Furthermore, it is suggested that the textual quality of memory reports should be taken more seriously, and that evaluation and interpretation are inherent aspects of personally significant memories.