Retrograde amnesia with transposition in the past: A neuropsychological and PET study of a case.

OBJECTIVE: Retrograde amnesia (RA) with a "transposition in the past" phenomenon has been rarely reported. Patients presenting disproportionate RA for all events over a defined period of time offer an opportunity to investigate the unclear relationship between autobiographical memory and the self, through the well-known self-memory system (SMS). METHOD: We report the case of a 31-year-old right-handed woman who presented to the emergency department of our tertiary care center with an ongoing episode of RA. After resolution of the episode, she had a second transient episode of RA. An extensive neuropsychological battery was performed to assess her autobiographical and nonautobiographical memory during and after the 2 episodes of RA. She also had an 18F-Fluorodeoxyglucose Positron Emission Tomography (FDG PET) scan during the second RA episode. RESULTS: During the 2 RA episodes, results showed lacunar amnesia for autobiographical as well as nonautobiographical memories of the time period between the present and the past 15 years, with preserved anterograde memory. Moreover, her memories before this lost period were more accurate than those after the 2 RA episodes. During the 2 RA episodes, our patient experienced a "transposition in the past" phenomenon. Statistical analysis of the PET scan demonstrated a significant hypometabolism within the right hippocampus. CONCLUSION: The "transposition in the past" phenomenon illustrates the relationship between both episodic and autobiographical memories and the functioning of self, according to the SMS model. Moreover, this case suggests the involvement of the hippocampus in this phenomenon. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Smell your memories: Positive effect of odor exposure on recent and remote autobiographical memories in Alzheimer's disease.

Introduction: There is a burgeoning interest in the effects of odor exposure on autobiographical memory in Alzheimer's disease (AD). We pursued this line of research by assessing the effect of odor exposure on the retrieval of recent and remote memories in AD. Method: Twenty-six patients with mild AD and 28 controls were tested in two conditions: with and without odor exposure. In each condition, participants were invited to retrieve two childhood memories, two adulthood memories, and two recent memories. Results: Analysis showed that AD patients produced a higher number of and more specific childhood memories, adulthood memories, and recent memories after odor exposure than without odor. Discussion: These findings demonstrate how odor exposure may alleviate anterograde and retrograde amnesia, at least when considering the ability of patients with mild AD to retrieve few recent or remote memories.

Prospective evaluation of first and last memory reports following moderate to severe traumatic brain injury.

Prospective monitoring of posttraumatic amnesia (PTA) status is recommended following traumatic brain injury (TBI). Use of patients' subjective reports is, however, still common and necessary in some circumstances. It is therefore important to understand how patients' self-reported first memories relate to prospective measures and how reliable these reports remain over time. In the present study, patients with moderate-severe TBI in PTA were asked about their first and last memories surrounding the injury daily and were administered the Westmead Post-Traumatic Amnesia Scale (WPTAS). Following PTA emergence, a semistructured interview was used to ascertain participants' reports of return of continuous memory after the injury, as well as their last preinjury memory. This interview was repeated six months later, along with the Community Integration Questionnaire to measure functional outcome and the Rey Auditory Verbal Learning Test to measure anterograde memory. The temporal order of recovery of WPTAS variables and subjective reports was determined, and consistency of subjective reports over time was examined using bivariate correlation and intraclass correlation coefficients (ICCs). Findings suggested that patients' reports of return of continuous memory aligned most closely with return of consistent orientation, and occurred significantly earlier than attainment of criterion on the WPTAS. Reported first memories were significantly later at follow-up (i.e., greater days post injury) and the ICC was not suggestive of adequate clinical reliability. Last memory reports were slightly more reliable, with 71% of cases remaining in the same band at follow-up. Demographic and injury-related variables were not significantly associated with the discrepancy between reports. The variability in patients' reports over time highlights the importance and value of prospective PTA monitoring.

Retrograde Personal Semantic Memory During Post-Traumatic Amnesia and Following Emergence.

OBJECTIVES: Anecdotal reports suggest that following traumatic brain injury (TBI) retrograde memories are initially impaired and recover in order of remoteness. However, there has been limited empirical research investigating whether a negative gradient in retrograde amnesia-relative preservation of remote over recent memory-exists during post-traumatic amnesia (PTA) compared with the acute phase post-emergence. This study used a repeated-measures design to examine the pattern of personal semantic (PS) memory performance during PTA and within two weeks of emergence to improve understanding of the nature of the memory deficit during PTA and its relationship with recovery. METHODS: Twenty patients with moderate-severe TBI and 20 healthy controls (HCs) were administered the Personal Semantic Schedule of the Autobiographical Memory Interview. The TBI group was assessed once during PTA and post-emergence. Analysis of variance was used to compare the gradient across lifetime periods during PTA relative to post-emergence, and between groups. RESULTS: PS memory was significantly lower during PTA than post-emergence from PTA, with no relative preservation of remote memories. The TBI group was still impaired relative to HCs following emergence from PTA. Lower overall PS memory scores during PTA were associated with increased days to emerge from PTA post-interview. CONCLUSIONS: These results suggest a global impairment in PS memory across lifetime periods particularly during PTA, but still present within 2 weeks of emergence from PTA. PS memory performance may be sensitive to the diffuse nature of TBI and may, therefore, function as a clinically valuable indicator of the likely time to emerge from PTA. (JINS, 2018, 24, 1064-1072).

Synapse-specific representation of the identity of overlapping memory engrams.

Memories are integrated into interconnected networks; nevertheless, each memory has its own identity. How the brain defines specific memory identity out of intermingled memories stored in a shared cell ensemble has remained elusive. We found that after complete retrograde amnesia of auditory fear conditioning in mice, optogenetic stimulation of the auditory inputs to the lateral amygdala failed to induce memory recall, implying that the memory engram no longer existed in that circuit. Complete amnesia of a given fear memory did not affect another linked fear memory encoded in the shared ensemble. Optogenetic potentiation or depotentiation of the plasticity at synapses specific to one memory affected the recall of only that memory. Thus, the sharing of engram cells underlies the linkage between memories, whereas synapse-specific plasticity guarantees the identity and storage of individual memories.

Episodic future thinking and future-based decision-making in a case of retrograde amnesia.

We investigated episodic future thinking (EFT) and future-based cognition and decision-making in patient SG, who developed a dense retrograde amnesia following hypoxia due to a cardiac arrest. Despite intact general cognitive and executive functioning, SG was unable to remember events from his entire lifetime. He had, however, relatively spared anterograde memory and general semantic knowledge. Voxel-based morphometry detected a reduction of gray matter in the thalamus, cerebellum and fusiform gyrus bilaterally, and, at a reduced threshold, in several regions of the autobiographical memory network, including the hippocampi. We show that SG is unable to imagine personal future events, but can imagine fictitious events not self-relevant and not located in subjective time. Despite severely impaired EFT, SG shows normal attitudes towards the future time, and normal delay discounting rates. These findings suggest that retrieval of autobiographical information from long-term memory is necessary for EFT. However, relatively spared anterograde memory and general semantic knowledge may be sufficient to allow construction of fictitious experiences. As well, EFT is not necessary to drive future-oriented cognition and choice. These findings highlight the relation between autobiographical memory and EFT, and the fractionation of human temporal consciousness. Moreover, they contribute to our understanding of retrograde amnesia as an impairment of memory as well as future thinking.

Dissociative amnesia: Disproportionate retrograde amnesia, stressful experiences and neurological circumstances.

Dissociative amnesias have been reported in neurological episodes mild enough to not cause any visible lesions on morphological examination. Disproportionate retrograde amnesia with or without identity loss happens in the context of psychological trauma (known or not). In metabolic imaging studies, some authors have reported functional alterations, particularly in the bilateral hippocampus, right temporal regions and inferolateral prefrontal cortex, despite normal morphological imaging. To avoid the presumption of an organic, psychogenic or mixed origin for such changes, De Renzi et al. suggested the term 'functional amnesia' to describe the condition. Patients have sometimes recovered during events similar to those preceding the amnesia in either a spectacular fashion or never. Also, in some cases, distraction or sedation may trigger the start of recovery. During psychotherapy, one patient remembered seeing a car on fire when he was a boy, and his amnesia started when his house was on fire. This suggests control by the frontal cortex, with repression blocking amnesic traces in the new emotional and biological context.

Transient Global Amnesia: Commentary on Trip Gabriel's First-Person Account.

This paper comments on a companion article, a first-person account of an episode of transient global amnesia written by New York Times reporter Trip Gabriel (Gabriel T. 2017. Cogn Behav Neurol. 30:1-4). Mr Gabriel describes having no memories of a cold, rainy day that he had spent on a sailboat competing in two races. The episode may have been triggered by his exposure to water. Afterward, the skipper recalled that Mr Gabriel had functioned fine on the boat, although after returning to shore he needed help finding his car. When he told his wife over the phone that he could not remember where he lived, she got him home and to the hospital. The staff excluded stroke and other causes of amnesia. He felt some awareness after about 9 hours, and the episode ended after about 23 hours. He has been left with a permanent memory gap of 12 hours.The commentary on the case outlines the state of knowledge about transient global amnesia. The diagnosis is well established: a witnessed sudden-onset retrograde and anterograde amnesia lasting <24 hours in a fully conscious person who knows who he/she is and has no other cause for amnesia. Triggers include exposure to water, stress, and sexual intercourse. A normal magnetic resonance imaging scan can help with the often challenging differential diagnosis. Apart from the gap in memory, patients recover fully and only 15% to 20% have recurrences. The underlying pathophysiology has not been explained.

Personal semantic and episodic autobiographical memories in Korsakoff syndrome: A comparison of interview methods.

OBJECTIVE: The temporal gradient in patients with Korsakoff's syndrome has been of particular interest in the literature, as many studies have found evidence for a steep temporal gradient, but others have observed more uniform remote memory impairment across all past time periods. Inconsistencies might be the result of the nature of remote memory impairment under study (i.e., nonpersonal or autobiographical memory) and of methodological differences in the examination of remote memory loss. The aim of this study was to examine whether differences between autobiographical memory interview (AMI) and autobiographical interview (AI) procedures influence the presence of a temporal gradient in semantic and episodic autobiographical memory in Korsakoff patients. METHOD: The procedure used in the present study combined the AMI and AI into one study session. We compared the performance of 20 patients with Korsakoff's syndrome and 27 healthy controls. First, participants were asked to recall knowledge from different life periods. Second, participants were asked to recall memories from five life periods. Thirdly, participants were asked to rate their subjective experience of each event recalled on a 5-point scale. Finally, we analyzed the findings in terms of all the memories recalled versus the first memory from each life-period only. RESULTS: Both the AMI and the AI showed a temporally graded retrograde amnesia in the Korsakoff patients for personal semantic and episodic autobiographical memories. The pattern of amnesia in Korsakoff patients was not affected by examining only one event per life-period. Subjective ratings of recalled memories were largely comparable between the groups. CONCLUSIONS: The findings were generally consistent across the AMI and AI. Varying the number of events did not affect the pattern of the gradient. Hence, the temporal gradient in Korsakoff patients is not an artefact of either the AMI or the AI method.

Functional (dissociative) retrograde amnesia.

Retrograde amnesia is described as condition which can occur after direct brain damage, but which occurs more frequently as a result of a psychiatric illness. In order to understand the amnesic condition, content-based divisions of memory are defined. The measurement of retrograde memory is discussed and the dichotomy between "organic" and "psychogenic" retrograde amnesia is questioned. Briefly, brain damage-related etiologies of retrograde amnesia are mentioned. The major portion of the review is devoted to dissociative amnesia (also named psychogenic or functional amnesia) and to the discussion of an overlap between psychogenic and "brain organic" forms of amnesia. The "inability of access hypothesis" is proposed to account for most of both the organic and psychogenic (dissociative) patients with primarily retrograde amnesia. Questions such as why recovery from retrograde amnesia can occur in retrograde (dissociative) amnesia, and why long-term new learning of episodic-autobiographic episodes is possible, are addressed. It is concluded that research on retrograde amnesia research is still in its infancy, as the neural correlates of memory storage are still unknown. It is argued that the recollection of episodic-autobiographic episodes most likely involves frontotemporal regions of the right hemisphere, a region which appears to be hypometabolic in patients with dissociative amnesia.

Forgetting "Novel" but Not "Dragon": The Role of Age of Acquisition on Intentional and Incidental Forgetting.

Two experiments studied how the age at which words are acquired (Age of Acquisition, AoA) modulates forgetting. Experiment 1 employed the retrieval-practice paradigm to test the effect of AoA on the incidental forgetting that emerges after solving competition during retrieval (i.e., retrieval-induced forgetting, RIF). Standard RIF appeared with late-acquired words, but this effect disappeared with early-acquired words. Experiment 2 evaluated the effect of AoA on intentional forgetting by employing the list-method directed forgetting paradigm. Results showed a standard directed forgetting effect only when the to-be-forgotten words were late-acquired words. These findings point to the prominent role of AoA in forgetting processes.

Thinking about the future can cause forgetting of the past.

People are able to imagine events in the future that have not yet happened, an ability referred to as episodic future thinking. There is now compelling evidence that episodic future thinking is accomplished via processes similar to those that underlie episodic retrieval. Drawing upon work on retrieval-induced forgetting, which has shown that retrieving some items in memory can cause the forgetting of other items in memory, we show that engaging in episodic future thinking can cause related autobiographical memories (Experiments 1-3) and episodic event descriptions (Experiments 3-4) to become less recallable in the future than they would have been otherwise. This finding suggests that episodic future thinking can serve as a memory modifier by changing the extent to which memories from our past can be subsequently retrieved.

Autobiographical Memory Specificity in Major Depression Treated With Electroconvulsive Therapy.

OBJECTIVE: Autobiographical memory in major depression is characterized by reduced specificity, which reflects the tendency to summarize categories of events rather than recall specific instances of events situated in a time and place. This widely studied cognitive marker for depression has not been extensively examined in patients treated with electroconvulsive therapy (ECT). METHODS: We conducted a retrospective chart review of a naturalistic cohort of patients receiving a course of brief-pulse predominantly bitemporal ECT for a major depressive episode. Patients completed the recent life section of the Kopelman Autobiographical Memory Interview (AMI) at pre-ECT baseline, end of treatment course, and 3-month follow-up as part of routine clinical practice. Mood was assessed using the 24-item Hamilton Rating Scale for Depression. RESULTS: We identified 48 patients (mean age, 61.6; female, 62.5%) meeting inclusion criteria. A total of 77.1% of patients responded to the ECT course, 29.7% subsequently relapsed. There were no significant changes over time on either AMI total score or semantic and episodic subscales. However, patients were markedly impaired on episodic autobiographical memory compared with the normative sample at all 3 assessment points, whereas personal semantic memory recall was normal. Specificity of episodic autobiographical memory at baseline did not predict response to ECT or likelihood of relapse. CONCLUSIONS: We found reduced specificity of episodic autobiographical memory in depressed patients before ECT, which persisted at long-term follow-up despite significant improvement in mood. The finding of no detectable retrograde amnesia likely reflects lack of sensitivity of the recent life section of the AMI to detect ECT-induced changes.

[Main interventions for rehabilitation of autobiographical memory in Alzheimer's disease from early to severe stage: a review and new perspectives]. / Prise en charge des troubles de la mémoire autobiographique dans la maladie d'Alzheimer du stade débutant au stade sévère : revue de la littérature et nouvelles perspectives.

Given the limitations of pharmacological treatments in Alzheimer's disease, many non-drug therapies have emerged in recent decades and are often offered in complement of pharmacological treatments. The cognitive rehabilitation interventions focused on memory are usual in Alzheimer's disease. Memory deficits are prominent from the early stages of the disease and cause detriment to patient autonomy in daily life. In particular, problems of identity and autobiographical memory, although still often overlooked in the patients' general neuropsychological profile, appear right away. Because of their more insidious negative influence, specific treatments are still underdeveloped. Rehabilitation of autobiographical memory is complex because it requires taking into account its multiple components, both semantic and episodic, but also understanding its links with personal identity. Thus, this article provides an overview of existing cognitive rehabilitation interventions of anterograde and retrograde autobiographical memory in Alzheimer's disease. We specify the contribution of new technologies to improve the consolidation of recent events memory and of a rehabilitation program of autobiographical memory - REMau -, derived from the TEMPau task, which takes into account the constructive nature of episodic memories via the personal semantic through different periods of life. The main aim is to examine what are the objectives, benefits and limitations of these interventions and to estimate how they can meet the more general problem of deficiency in personal identity. As identity is constructed on the basis of past experience, but is modulated by new experiences, our current challenge is to associate combined treatments of anterograde and retrograde memory based on the interaction between autobiographical memory and the self.

Human amnesia and the medial temporal lobe illuminated by neuropsychological and neurohistological findings for patient E.P.

We present neurohistological information for a case of bilateral, symmetrical damage to the medial temporal lobe and well-documented memory impairment. E.P. developed profound memory impairment at age 70 y and then was studied for 14 y He had no capacity for learning facts and events and had retrograde amnesia covering several decades. He also had a modest impairment of semantic knowledge. Neurohistological analysis revealed bilaterally symmetrical lesions of the medial temporal lobe that eliminated the temporal pole, the amygdala, the entorhinal cortex, the hippocampus, the perirhinal cortex, and rostral parahippocampal cortex. The lesion also extended laterally to involve the fusiform gyrus substantially. Last, the superior, inferior, and middle temporal gyri were atrophic, and subjacent white matter was gliotic. Several considerations indicate that E.P.'s severe memory impairment was caused by his medial temporal lesions, whereas his impaired semantic knowledge was caused by lateral temporal damage. His lateral temporal damage also may have contributed to his extensive retrograde amnesia. The findings illuminate the anatomical relationship between memory, perception, and semantic knowledge.