A Neurocognitive Perspective on the Forms and Functions of Autobiographical Memory Retrieval

Autobiographical memory retrieval involves constructing mental representations of personal past episodes by associating together an array of details related to the retrieved event. This construction process occurs flexibly so that the event details can be associated together in different ways during retrieval. Here, we propose that differences in how this association occurs support a division in autobiographical remembering. We first review theories of autobiographical memory organization that suggest that episodic details of an experience are processed along a gradient of abstraction. This organization allows for the same autobiographical event to be recalled as either a conceptualized or perceptually-based episodic memory. We then use neuroimaging evidence to show how this division within episodic autobiographical memory is also present in the brain, both at a network level and within the hippocampus. Specifically, we suggest that the anterior and posterior hippocampus are obligatorily tuned towards constructing conceptual vs. perceptual episodic representations of autobiographical memories. Finally, we discuss the directive purpose of this proposed division of episodic remembering by reviewing decision scenarios that benefit from recalling the past as a conceptual vs. a perceptual episode. Conceptual remembering is useful to guide ambiguous decisions that have yet to be encountered whereas perceptual remembering is useful to guide decisions for well-structured tasks that have been previously experienced. We emphasize that the ability to shift between conceptual and perceptual forms of remembering, by virtue of hippocampal specialization, during decision-making and other memory-guided actions is the key to adaptive behavior

The neural dynamics of individual differences in episodic autobiographical memory

The ability to mentally travel to specific events from one’s past, dubbed episodic autobiographical memory (E-AM), contributes to adaptive functioning. Nonetheless, the mechanisms underlying its typical interindividual variation remain poorly understood. To address this issue, we capitalize on existing evidence that successful performance on E-AM tasks draws on the ability to visualize past episodes and reinstate their unique spatiotemporal context. Hence, here, we test whether features of the brain’s functional architecture relevant to perceptual versus conceptual processes shape individual differences in both self-rated E-AM and laboratory-based episodic memory (EM) for random visual scene sequences (visual EM). We propose that superior subjective E-AM and visual EM are associated with greater similarity in static neural organization patterns, potentially indicating greater efficiency in switching, between rest and mental states relevant to encoding perceptual information. Complementarily, we postulate that impoverished subjective E-AM and visual EM are linked to dynamic brain organization patterns implying a predisposition towards semanticizing novel perceptual information. Analyses were conducted on resting state and task-based fMRI data from 329 participants (160 women) in the Human Connectome Project (HCP) who completed visual and verbal EM assessments, and an independent gender diverse sample (N = 59) who self-rated their E-AM. Interindividual differences in subjective E-AM were linked to the same neural mechanisms underlying visual, but not verbal, EM, in general agreement with the hypothesized static and dynamic brain organization patterns. Our results suggest that higher E-AM entails more efficient processing of temporally extended information sequences, whereas lower E-AM entails more efficient semantic or gist-based processing

Altering access to autobiographical episodes with prior semantic knowledge

Within autobiographical knowledge, semantic and episodic memory are traditionally considered separate, but newer models place them along a continuum, which raises the possibility of an intermediate form of knowledge - personal semantics. This study tested how different types of semantics – general semantics and two forms of personal semantics – impact access to personal episodic memories. In two experiments, participants made a series of true/false judgments about a prime statement, which reflected a general semantic fact, a context-dependent (e.g., repeated event) or context-independent (e.g., trait), personal semantic fact and then retrieved a specific past episodic memory. There was a significantly stronger priming effect for accessing specific episodic memories after judging personal semantic facts versus general facts. We also found that context-dependent and -independent personal semantic facts had separable priming effects on episodic memory. These findings support a continuum model of memory and verifies that there are multiple forms of personal knowledge

Deformation-based shape analysis of the hippocampus in the semantic variant of primary progressive aphasia and Alzheimer’s disease

Background Increasing evidence shows that the semantic variant of primary progressive aphasia (svPPA) is characterized by hippocampal atrophy. However, less is known about disease-related morphological hippocampal changes. The goal of the present study is to conduct a detailed characterization of the impact of svPPA on global hippocampus volume and morphology compared with control subjects and patients with Alzheimer’s disease (AD). Methods We measured hippocampal volume and deformation-based shape differences in 22 patients with svPPA compared with 99 patients with AD and 92 controls. Multiple Automatically Generated Templates Brain Segmentation Algorithm (MAGeT-Brain) was used on MRI images obtained at the diagnostic visit. Results Comparable left and right hippocampal atrophy were observed in svPPA and AD. Deformation-based shape analysis showed a common pattern of morphological deformation in svPPA and AD compared with controls. More specifically, both svPPA and AD showed inward deformations in the dorsal surface of the hippocampus, from head to tail on the left side, and more limited to the anterior portion of the body in the right hemisphere. These results also pointed out that both diseases are characterized by a lateral displacement of the central part (body) of the hippocampus. Discussion Our study provides critical new evidence of hippocampal morphological changes in svPPA, similar to those found in AD. These findings highlight the importance of considering morphological hippocampal changes as part of the anatomical profile of patients with svPPA

Conceptual relatedness promotes memory generalization at the cost of detailed recollection

Abstract An adaptive memory system is one that allows us to both retrieve detailed memories as well as generalize knowledge about our past, the latter termed memory generalization and is useful for making inferences about new situations. Research has indicated that memory generalization relies on forming knowledge structures by integrating experiences with shared encountered elements. Whether memory generalization occurs more readily when  experiences also have elements that share established (conceptual) information is less clear. It is also unclear if engaging in memory generalization during learning comes at the cost of retrieving detailed memories, the other function of episodic memory. To address these two knowledge gaps, we paired a modified version of the acquired equivalence task with a recognition memory test. Across three experiments, participants first learned a series of overlapping object-scene pairs (A–X, B–X and A–Y) in which half of the overlapping pairs contained conceptually-related objects (e.g., A—pencil; B—scissors; conceptual condition) and the other half contained unrelated objects (neutral condition). Participants ability to generalize to new overlapping object-scene pairs (B–Y) as well as not-learned but semantically-related objects was measured. Finally, participants completed a recognition memory test that included the encoded objects, perceptually similar lures or new foil objects. Across all experiments, we found higher rates of generalization but reduced detailed memory (indexed by increased false alarms to lure objects) for information learned in the conceptual than neutral condition. These results suggest the presence of conceptual knowledge biases an individual towards a generalization function of memory, which comes at the expense of detailed recollection

Conceptual Similarity Promotes Memory Generalization At the Cost of Detailed Recollection

The aim of the project was to investigate the critical role of prior conceptual knowledge in driving knowledge generalization, and whether this comes at an expense of forming detailed memories. Over three experiments, healthy participants performed a modified version of the acquired equivalence test in which they learned overlapping object-scenes associations (A-X, B-X and A-Y) and then generalized the acquired knowledge to indirectly learned associations (B-Y) and novel objects (C-X and C-Y) that were from the same conceptual category (e.g. A - pencil; B - scissors) and different categories (e.g. A - watch; B - fork). In a subsequent recognition memory task, participants made old/new judgements to old (targets), similar (lures) and novel items. We found consistent evidence that forming associations of objects that had similar conceptual features led to higher rates of generalization but reduced detailed memory for the same objects, showcasing how memory processes can shift when learning

Beyond Episodic Memory: Medial Temporal Lobe Contributions to Problem-solving and Semantic Fluency Tasks

The purpose of this thesis was to examine the contribution of episodic memory processes supported by the medial temporal lobes (MTL) to two goal-oriented non-episodic tasks, problem solving and semantic retrieval (verbal fluency). The reported experiments provide evidence for the hypothesis that MTL-based episodic processes are robustly involved in completing non-episodic tasks that are open-ended in that no algorithm or procedure can be applied to obtain task-relevant information. In Experiments 1 and 2, participants were administered the Means-End-Problem-Solving (MEPS) task, an open-ended test of social problem solving. People with impaired episodic memory associated with MTL damage or deterioration, patients with temporal lobe epilepsy or excisions (TLE) and older adults, performed worse than matched controls at solving such problems. Importantly, the participants’ performance on the MEPS as judged by the number of relevant solution steps generated correlated with the number of internal (episodically-relevant) but not external (semantically-relevant) details provided in the solutions. Thus, information derived from episodic memory benefited performance on the MEPS. Experiments 3 and 4 were conducted to ascertain whether open-endedness and episodic relevance are determinants of MTL contributions to performance on tests of verbal fluency, which traditionally are considered the domain of semantic memory. Using fMRI, Experiment 3 tracked the time course of MTL activation as participants performed a fluency task for categories that ranged in episodic relevance. The MTLs were more active throughout for categories that depended on autobiographical memories, not active for categories that were not episodically relevant, and active for episodic/spatial categories only later in the time course as the task moved from being well-defined to open-ended. The necessary involvement of the MTL in these tasks was confirmed by the pattern of spared and impaired performance of patients with TLE on category fluency tasks (Experiment 4). Together, these findings are consistent with the view that MTL-based processes are involved in tasks beyond those that test episodic memory. Furthermore, these studies suggest that performance on non-episodic tasks recruits the MTL most robustly when a task is open-ended.Ph

Emotional cue effects on autobiographical memory access and construction

If remembering the past requires a cue to stimulate mental reactivation of an experience (i.e., a memory), then the nature of the retrieval cue can bias how that experience is recalled. Based on the established link between emotion and memory, we tested how two emotional properties of a cue - valence (positive and negative) and arousal (high and low) - influence different phases of autobiographical memory retrieval: accessing an autobiographical episode and then re-constructing the associated, detailed memory representation. Young, healthy participants completed two experimental sessions that were separated by 24 to 48 hours. In session one, participants used musical retrieval cues that varied in emotional valence and arousal to access autobiographical memories. Cue-evoked physiological arousal and valence responses were measured via skin conductance and facial electromyography, respectively, as were the reaction times to access each memory. In session two, participants reactivated and then described in detail the memories that were accessed in session one, and the resultant descriptions were scored for the number of specific episodic (internal) and non-episodic (external) details. While arousal and valence levels of the retrieval cues, as well as the evoked physiological responses, significantly predicted the reaction time to access a memory, only cue arousal predicted how detailed the representations were constructed. Memories that were initially accessed to high-arousing cues were described with more episodic details than memories accessed to low-arousing cues. These data provide new insights into how emotional valence and arousal levels of retrieval cues distinctly bias the accessibility and detailed construction of autobiographical memories

L’art-thérapie de groupe en lien avec la dimension psychosociale de l’épilepsie : une étude préliminaire à méthodes mixtes et le point de vue qu’elle propose

This article consists of a preliminary study that chronicles an 8-week group art therapy program for people with epilepsy, located in a fine-art museum setting. The study is situated in theories of psychosocial stigma. The primary purpose was to explore whether art therapy could be an effective method to address the psychosocial component of epilepsy treatment in Canada. Secondary questions explored the roles of an open-studio approach and an art therapy program delivered in a fine-art museum context. A mixed-methods (convergent, parallel) design examined the program’s impact for six adults between the ages of 18 and 45 with epilepsy. Psychosocial questionnaires and interviews were administered before and after the group program, and session artworks were examined with Appleton’s (2001) art therapy trauma paradigm. Two groups were compared based on attendance (i.e., attend versus no-attend). Participants who had attended group sessions had substantially reduced scores on questionnaires assessing stress and depression and increased scores on questionnaires assessing self-esteem and quality of life compared to participants who did not attend. The interviews revealed that art therapy increased the attend group’s ability to talk about the impact of epilepsy, to express grief, to make social connections, to navigate treatment stress, and to foster emotional regulation. Group art therapy may improve the psychosocial treatment dimension of epilepsy while acknowledging systemic stigma and social barriers.On présente une étude préliminaire qui relate sous forme de chronique un programme d’art-thérapie de groupe échelonné sur 8 semaines se déroulant dans le contexte d’un musée des beaux-arts et qui est destiné à des personnes souffrant d’épilepsie. L’étude s’inspire des théories sur la stigmatisation psychosociale. Elle a pour principal objectif d’explorer si l’art-thérapie pourrait constituer une méthode efficace pour aborder la composante psychosociale du traitement de l’épilepsie au Canada. Parmi les questions secondaires, citons l’exploration des rôles dans une approche de studio ouvert et un programme d’art-thérapie se déroulant dans le contexte d’un musée des beaux arts. On a eu recours à un concept de méthodes mixtes (convergente, parallèle) pour examiner l’impact du programme sur six adultes âgés de 18 à 45 ans et atteints d’épilepsie. On a mené des entrevues psychosociales et soumis des questionnaires avant et après le programme de groupe, puis on a utilisé le paradigme d’Appleton pour faire les comparaisons. On a comparé deux groupes en fonction de leurs présences (c.-à-d. les personnes qui étaient présentes comparativement à celles qui ne l’étaient pas). Les personnes qui étaient présentes aux rencontres de groupe présentaient des scores considérablement moins élevés dans leurs réponses aux questionnaires sur le stress et la dépression, ainsi que des scores plus élevés dans les questionnaires d’évaluation de l’estime de soi et de la qualité de vie comparativement aux membres qui étaient absents. Les entrevues ont révélé que l’art-thérapie avait permis d’accroître l’aptitude des membres du premier groupe à discuter des effets de l’épilepsie, à exprimer leur douleur, à établir des liens sociaux, à s’adapter au stress du traitement et à favoriser la régulation des émotions. L’art-thérapie de groupe peut améliorer la dimension psychosociale du traitement de l’épilepsie, tout en reconnaissant la stigmatisation systémique et les obstacles sociaux