[Memory alterations in post-traumatic stress disorder]. / Les altérations de la mémoire dans le trouble de stress post-traumatique.

Post-Traumatic Stress Disorder (PTSD) is a disorder that develops following the experience of a highly stressful event, which involves a confrontation with death or the threat of death, serious injury or sexual violence. It is characterized by symptoms such as intrusions, avoidance and hypervigilance. According to the literature, PTSD is associated with an imbalance between a privileged memorization of the emotional and sensory aspects of the traumatic event and a failure to memorize the contextual aspects. That is why PTSD is now considered a memory disorder whose effects extend to several components. In this review article, we focus on how PTSD affects long-term memory. The first part describes the long-term effects of PTSD on episodic memory with emphasis on the difficulties in encoding certain elements of the traumatic event and their consequences. These difficulties may be manifested in the narration of the trauma, with a discourse of the traumatic event lacking in contextual details. They may also lead to reliving and generalizing the fear to other contexts, whether they are related to the trauma or not. The second part of the article discusses how PTSD affects autobiographical memory and has consequences for the construction of identity and the perception of the past, present and future of people with this disorder. Autobiographical memory, which plays a key role in the storage of past personal memories as well as in identity formation, shows several forms of disruption induced by PTSD. First, a decrease in contextual details associated with memories of the personal past is observed, meaning that people with PTSD tend to remember their past experiences less accurately. Second, a propensity to project the future in a more negative and unpredictable manner is evidenced, related to a feeling of uncertainty about the future in PTSD suffering individuals. Finally, alterations in the encoding of present events due to the disruptive effects of post-traumatic stress symptoms during the encoding process are also identified.

Title: Les altérations de la mémoire dans le trouble de stress post-traumatique. Abstract: Le Trouble de Stress Post-Traumatique (TSPT) est une pathologie qui se développe chez une personne qui a fait l'expérience d'un événement hautement stressant impliquant une confrontation à la mort ou à une menace de mort, à une blessure grave ou à des violences sexuelles. Ce trouble se caractérise par plusieurs symptômes dont les intrusions, l'évitement et l'hypervigilance. Le TSPT est associé à un déséquilibre entre une mémorisation exacerbée des aspects émotionnels et sensoriels de l'événement traumatique et un défaut de mémorisation des aspects contextuels. En conséquence, le TSPT est aujourd'hui considéré comme un trouble de la mémoire dont les retentissements s'étendent à plusieurs de ses composantes. Cet article expose les conséquences du TSPT sur la mémoire à long terme et met la focale sur deux mécanismes : l'encodage partiel de l'événement traumatique en mémoire épisodique et l'influence de cette expérience traumatique sur les souvenirs personnels en mémoire autobiographique. L'article aborde en première partie les difficultés d'encodage de certains éléments de l'événement traumatique et leurs conséquences, comprenant les reviviscences ainsi que la persistance et la généralisation de la peur à d'autres contextes plus ou moins liés à l'événement traumatique. La deuxième partie aborde la façon dont le trouble affecte la mémoire autobiographique et l'identité en occasionnant une réduction de la précision des événements du passé, des altérations de la capacité à se projeter dans des événements futurs et un encodage incomplet de nouveaux événements.

Disruption in normal correlational patterns of metabolic networks in the limbic circuit during transient global amnesia.

Transient global amnesia is characterized by the sudden apparition of severe episodic amnesia, mainly anterograde, associated with emotional changes. Even though the symptoms are stereotyped, cerebral mechanism underlying transient global amnesia remains unexplained and previous studies using positron emission tomography do not show any clear results or consensus on cerebral regions impacted during transient global amnesia. This study included a group of 10 transient global amnesic patients who underwent 18F-fluorodeoxyglucose positron emission tomography during the acute or recovery phase of the episode and 10 paired healthy controls. Episodic memory was evaluated with the encoding-storage-retrieval paradigm and a story recall test of the Wechsler's memory scale and anxiety was assessed with the Spielberger scale. We used statistical parametric mapping to identify modifications of whole-brain metabolism. Regarding hypometabolism, there was no brain region systematically affected in all transient global amnesic patients and the comparison between amnesic patients and controls did not show any significant differences. To better understand the specific implication of the limbic circuit in the pathophysiology of transient global amnesia, we then conducted a correlational analysis that included regions of this network. Our findings showed that in healthy controls, regions of the limbic circuit seem to operate in a synchronized way with all regions being highly correlated to each other. On the opposite, in transient global amnesic patients, we observed a clear disruption of this normal correlational patterns between regions with the medial temporal lobe (the hippocampus, parahippocampal gyrus and amygdala) included in one cluster and the orbitofrontal cortex, anterior and posterior cingulate gyrus and thalamus gathered in the other one. Given the individual variability in the time course of transient global amnesia, the direct comparison between a group of patients and controls does not seem to favour the identification of subtle and transient alterations in regional metabolism. The involvement of an extended network, such as the limbic circuit, seems more likely to explain the symptoms of patients. Indeed, the synchronization of regions within the limbic circuit seems to be altered during transient global amnesia, which could explain the amnesia and anxiety observed in transient global amnesic patients. The present study thus deepens our understanding of the mechanisms underlying not only amnesia but also the emotional component of transient global amnesia by considering it as a disruption in the normal correlational patterns within the limbic circuit.

[Memory tests]. / Tests de mémoire.

MEMORY TESTS. Memory tests used in clinical practice mainly concern anterograde memory through the evaluation of learning, short- or long-term retention, and retrieval of information. They use different types of material (verbal or visual) and different tasks to assess the integrity of the different memory processes: encoding, storage and retrieval.

TESTS DE MÉMOIRE. Les tests de mémoire utilisés en pratique clinique concernent principalement la mémoire antérograde au travers de l'évaluation des capacités d'apprentissage, de maintien à court ou long terme des informations, et de récupération de celles-ci. Ils utilisent différents types de matériel (verbal ou visuel) et différentes tâches permettant de statuer sur l'intégrité des différents processus mnésiques : encodage, stockage et récupération.

Episodic Autobiographical Memory Impairment and Differences in Pronoun Use: Study of Self-Awareness in Functional Amnesia and Transient Global Amnesia.

The subjective experience associated to memory processing is the core of the definition of episodic autobiographical memory (EAM). However, while it is widely known that amnesia affects the content of memories, few studies focused on the consequences of an impairment of EAM on the subjective self, also called the I-self. In the present study, we explored the I-self in two puzzling disorders that affect EAM: functional amnesia, which has an impact on autobiographical memory, and transient global amnesia (TGA), which only affects episodic memory. I-self was assessed through an original measure of self-integration in autobiographical narratives, namely the use of general or personal pronouns. Results showed that patients with functional amnesia tended to use general pronouns, whereas patients with TGA preferentially used the first person. The link between I-self and depersonalization-derealisation tendencies was also explored, showing dissociative tendencies in patients with functional amnesia but not in patients with TGA. We discuss these results from a combined neuropsychological and psychopathological perspective, with a view to proposing an explanatory model of the links between self-awareness and the episodic component of autobiographical memory.

Self-awareness in Transient Global Amnesia: distinguishing the effects of transient memory disorder vs. pre-existing vulnerability factors.

Numerous evidences suggest the existence of relationships between the impairment of episodic memory, acute stress exposure and variations in self-awareness (SA). Here, we examined 27 patients presenting transient global amnesia (TGA), a clinical condition which combines episodic amnesia and high anxiety, thanks to state and trait questionnaires of SA. We observed variation of SA depending on the stage of TGA (acute, recovery and follow-up). We also found preexisting differences in patient's awareness of their own image when the precipitating event was physical, encouraging us to give more consideration to the social determinants of stress in physiological cascade of TGA.

Short-Term Memory Span and Cross-Modality Integration in Younger and Older Adults With and Without Autism Spectrum Disorder.

This study tested whether adults with autism spectrum disorder (ASD) show the same pattern of difficulties and absence of age-related differences in short-term memory (STM) as those that have been reported in episodic long-term memory (LTM). Fifty-three adults with ASD (age range: 25-65 years) were compared to 52 age-, biological sex-, and intelligence-matched typically developing (TD; age range: 21-67 years) adults on three STM span tasks, which tested STM performance for letters (Verbal), grid locations (Visuospatial), or letters in grid locations (Multimodal). A subsample of 34 TD and 33 ASD participants ranging in age from 25 to 64 years completed a fourth Multimodal Integration task. We also administered the Color Trails Test as a measure of executive function. ASD participants' accuracy was lower than that of the TD participants on the three span tasks (Cohen's d: 0.26-0.50). The Integration task difference was marginally significant (p = .07) but had a moderate effect size (Cohen's d = 0.50). Regression analyses confirmed reduced STM performance only for older TD participants. Analyses also indicated that executive processes played a greater role in the ASD group's performance. The demonstration of similar difficulties and age-related patterning of STM in ASD to those documented for LTM and the greater recruitment of executive processes by older ASD participants on the Integration task suggest a compensatory role of frontal processes both as a means of achieving undiminished task performance and as a possible protection against older age cognitive decline in ASD. Longitudinal research is needed to confirm this. Autism Res 2020, 13: 1970-1984. © 2020 The Authors. Autism Research published by International Society for Autism Research and Wiley Periodicals LLC. LAY SUMMARY: Little is known about short-term memory (STM) in younger and older adults with autism spectrum disorder (ASD). This study tested different kinds of STM and showed that ASD adults remembered shorter sequences of letters, crosses, or letters in grid cells less well than matched participants with typical development. However, older ASD individuals performed similarly to younger ASD individuals, nor showing the reduction in performance usually seen with older age. The data suggest that ASD individuals use different underlying mechanisms when performing the tasks and that this might help protect their memory as they grow older.

Influence of depressive symptoms on memory in transient global amnesia.

INTRODUCTION: Recent studies have shown that patients with transient global amnesia (TGA) experience a depressive mood during the episode. However, little evidence has been found of possible mood congruency effects on memory, which are probably masked by the massive anterograde amnesia. An implicit assessment could provide a means of settling this question. METHODS: First, we measured patients' emotional states on psychopathological scales. Second, we administered a lexical decision task to assess three priming effects: Semantic priming (SP; table-chair), emotional priming (EP; murder-garbage), and emotional plus semantic priming (ESP; cemetery-coffin). RESULTS: Patients displayed a more depressed mood than controls. For patients, we found a SP effect in the ESP condition and a striking inhibition effect (i.e., negative target recognized more slowly when preceded by a negative prime rather than a neutral one) in the EP condition. For controls, a priming effect was found in the SP and ESP conditions, but not the EP condition. Finally, whereas the priming effect was greater in SP than in the other two conditions for controls, for patients it was the EP condition that stood out from the other two, being the only condition that led to an inhibition effect. CONCLUSIONS: We highlighted a mood congruency effect in TGA which could impel patients to focus their attention on negative information. While the negative valence of items always led to a slowdown in reaction times for both patients and controls, attesting to a negativity bias, this bias was greater in patients, leading to an inhibition effect.

Preserved Self-Evaluation in Amnesia Supports Access to the Self through Introspective Computation.

Encounters with new people result in the extraction and storage in memory of both their external features, allowing us to recognize them later, and their internal traits, allowing us to better control our current interactions with them and anticipate our future ones. Just as we extract, encode, store, retrieve and update the representations of others so, too, do we process representations of ourselves. These representations, which rely on declarative memory, may be altered or cease to be accessible in amnesia. Nonetheless, studies of amnesic patients have yielded the surprising observation that memory impairments alone do not prevent patients from making accurate trait self-judgments. In this review article, we discuss prevailing explanations for preserved self-evaluation in amnesia and propose an alternative one, based on the concept of introspective computation. We also consider molecular and anatomical aspects of brain functioning that potentially support introspective computation.

Physiological and Cognitive Effects of Acute Normobaric Hypoxia and Modulations from Oxygen Breathing.

INTRODUCTION: The emergence of normobaric devices for hypoxia awareness training makes crucial the study of physiological and cognitive effects induced by acute normobaric hypoxia (NH) exposure. Our study aimed to 1) investigate the effects of acute NH exposure on physiological variables and working memory; and 2) investigate the physiological and cognitive effects of oxygen breathing before and after acute NH exposure. METHODS: There were 86 healthy men who were randomized into 4 groups: the Normoxia-Air group (N = 23), whose subjects were breathing air; the Hypoxia-Air group (N = 22), where NH exposure was preceded and followed by air breathing; the Normoxia-O2group (N = 21), whose protocol was similar to the Normoxia-Air group, except with the addition of 100% O2breathing periods; and the Hypoxia-O2group (N = 20), whose participants were exposed to 100% O2before and after NH exposure. Working memory was assessed with the Paced Auditory Serial Addition Test. Peripheral oxygen saturation (Spo2), heart rate (HR), and electroencephalogram (EEG) were recorded. RESULTS: Acute NH exposure induced a classical physiological response (i.e., decreased Spo2and increased HR), but not identical to the well-described physiological response to acute hypobaric hypoxia. Acute NH also caused a strong impairment in working memory. Oxygen breathing following NH exposure induced a slowing in the EEG associated with a worsening of working memory performance. DISCUSSION: Acute NH exposure revealed a good surrogate for the classical hypobaric chamber for refresher hypoxia awareness training. Because the association between hypoxia and hyperoxia seems deleterious for the brain, we suggest that NH exposure should be surrounded by air breathing.

The Still Enigmatic Syndrome of Transient Global Amnesia: Interactions Between Neurological and Psychopathological Factors.

Transient global amnesia (TGA) is a neurological syndrome that usually occurs in middle-aged or older people. It is characterized by the abrupt onset of profound anterograde amnesia, associated with more variable retrograde amnesia and repetitive questioning. The whole episode lasts no more than 24 h. Almost 60 years after its first descriptions, the etiology of TGA remains unknown. Until now, TGA has been described exclusively as a memory disorder, but there is a growing body of evidence to show that emotional and psychological factors (as anxious and depressive symptoms) are present at different times of TGA. Their role therefore needs to be clarified. First, these factors seem to play a part in triggering TGA, at least for a subgroup of patients, suggesting the existence of an emotional TGA subtype. Second, recent research shows that almost all the TGA patients displayed modifications of their emotional state during the episode, possibly linked to sudden memory loss. The level of depressive and anxious symptoms could even reach a pathological threshold in patients with the so-called "emotional TGA subtype". Third, the persistence of these depressive and anxious symptoms after the end of the episode could account for lasting memory disorders in some patients. Finally, the analysis of these emotional syndrome and emotional factors and the recent data in neuroimaging could allow us to gain a better understanding of the pathophysiological mechanisms behind TGA. The aim of this review was thus to discuss whether the anxious and depressive symptoms are causative, resultant or coincidental of TGA.

Binding in working memory and frontal lobe in normal aging: is there any similarity with autism?

Some studies highlight similarities between Autism Spectrum Disorder (ASD) and healthy aging. Indeed, the decline in older individuals' ability to create a unified representation of the individual features of an event is thought to arise from a disruption of binding within the episodic buffer of working memory (WM) as the same way as observed in ASD. In both cases, this deficit may result from an abnormal engagement of a frontohippocampal network. The objective of the present study is to identify both cognitive processes and neural substrates associated with the deficit of binding in WM in healthy aging. We studied the capacity of binding and the cognitive processes that might subtend its decline in 72 healthy participants aged 18-84 years. We examined the behavioral data in relation to the changes in brain metabolism associated with the age-related decline in a subgroup of 34 healthy participants aged 20-77 years using the resting-state [(18)F] fluorodeoxyglucose positron emission tomography ((18)F-FDG PET). Forward stepwise regression analyses showed that the age-related decline in binding was partially explained by a decline in inhibition and processing speed. PET correlation analyses indicated that metabolism of the frontal regions, anterior and middle cingulate cortices is implicated in this phenomenon. These data suggest that executive functions and processing speed may play a crucial role in the capacity to integrate unified representations in memory in aging. Possible implications are discussed in ASD.

Mental simulation of future scenarios in transient global amnesia.

Researchers exploring mental time travel into the future have emphasized the role played by episodic memory and its cerebral substrates. Recently, owing to controversial findings in amnesic patients, this role has become a matter of intense debate. In order to understand whether episodic memory is indeed crucial to future thinking, we assessed this ability in 11 patients during an episode of transient global amnesia (TGA), a unique and severe amnesic syndrome that primarily affects episodic memory. In the first of two experiments, TGA patients were asked to recall personal past events as well as to imagine personal future events, without any guidance regarding content. Under this condition, compared with controls, they provided fewer past and fewer future events, and the latter were less closely related to their personal goals. Furthermore, TGA patients׳ descriptions of past and future events were scant, containing fewer descriptive elements in total and fewer internal details. In order to assess whether TGA patients might have been basing their future event narratives on their general knowledge about how these events usually unfold, in our second experiment, we asked them to imagine future events in response to short descriptions of common scenarios. Under this condition, inherently eliciting less detailed descriptions, not only were all the TGA patients able to describe common events as happening in the future, but their narratives contained comparable amounts of internal detail to those of controls, despite being less detailed overall. Taken together, our results indicate that severe amnesia interferes with TGA patients׳ ability to envisage their personal past and future on a general level as well as in detail, but less severely affects their ability to imagine common scenarios, which are not related to their personal goals, probably owing to their preserved semantic memory, logical reasoning and ability to create vivid mental images.

Just do it! How performing an action enhances remembering in transient global amnesia.

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of a massive episodic memory deficit that spares other cognitive functions. As such, it provides a unique human amnesia model for testing the enactment effect (i.e., better memory for performed actions than for verbally encoded sentences). Our main aim was to test whether the enactment effect is preserved in TGA patients, both to have a better understanding and to test the robustness of this effect in a massive amnesia. Object-action pairs were encoded under four conditions: verbal, experimenter-performed, and two enacted conditions (self-performed and self-performed with choice). We tested object-action pair retrieval using cued recall (CR) and recognition tasks, and source memory using a free recall task. We also assessed binding, executive functions, short-term memory, episodic memory, anxiety and mood. We run correlations to control for their putative effects on memory for action. Data were collected from 24 patients, 16 of whom were examined during the acute phase and eight the day-after, as well as from 18 healthy controls. The memory performances of the patients in the acute phase improved for both (i) the CR score, between the verbal, experimenter-performed and self-performed with choice conditions, and (ii) the total recognition score, between the verbal condition and the two enacted conditions. Correlations were found between self-performed task (SPT) enhancement and both the binding and anxiety. In spite of their severely impaired episodic memory, patients with TGA benefit from the enactment effect. These results are discussed in relation to the role of motor components and episodic integration in memory for actions. We suggest that enactment effect can be used in clinical practice and rehabilitation, possible even for patients with a massive memory impairment.

Working memory impairment in pilots exposed to acute hypobaric hypoxia.

INTRODUCTION: During an acute hypoxia exposure, impairment of memory is one of the most frequently reported symptoms, either during hypoxia awareness training of aircrews or after an in-flight hypoxic incident. However, the effects of acute hypoxia on memory have been little studied in laboratory-controlled conditions. Moreover, none of these studies were performed in hypobaric conditions. The main aim of our study was to investigate the effects of acute hypobaric hypoxia on working memory (WM). This study also aimed to find links between physiological measurements and cognitive performance during acute hypoxia exposure. METHODS: During hypoxia awareness training, 28 subjects (experimental group) were exposed to a simulated altitude level of 10,000 m (31,000 ft) in a hypobaric chamber, while 29 subjects (control group) stayed at sea level. WM was assessed in both groups with the Paced Auditory Serial Addition Test (PASAT). Peripheral oxygen saturation (SpO2) and heart rate were recorded. RESULTS: WM was strongly impaired in the hypoxic group. One major finding is that hypoxia highly increased the mean error frequency rate. WM performance decreased linearly with hypoxemia, but SpO2 was weakly predictive of PASAT performance and vice versa. DISCUSSION: WM is impaired by acute hypobaric hypoxia. Given the importance of WM in aircraft piloting and its sensitivity to hypoxia, the PASAT, in association with SpO2 and EEG recordings, could improve both hypoxia training and our understanding of the effects of hypoxia on memory.

Awareness of disease state without explicit knowledge of memory failure in transient global amnesia.

INTRODUCTION: Transient global amnesia (TGA) is a syndrome characterised by the rapid onset of antero- and retrograde amnesia, accompanied by temporal disorientation and iterative questioning. It is now established that the acute phase is associated with a raised level of anxiety and a depressed mood. We conducted a thorough investigation of patients' perceptions of their disease state, focusing on the links between their lack of explicit knowledge of amnesia during the acute phase and their emotional experience. METHOD: Explicit knowledge of memory deficits was assessed during TGA by means of an original scale inspired by Bisiach et al. (1986) and self-reported scales measuring patients' perceptions of their current memory and their cognitive and behavioural functioning. At the same time, we probed the patients' emotional experience (sources of worry, and levels of worry, anxiety and depression) via questionnaires. Data were collected from 20 patients in the acute phase, 16 in the peri-acute phase, 16 who were assessed the day after the episode and 14 healthy controls. Each patient underwent a follow-up examination 2 months later. RESULTS: Patients in the acute phase displayed a lack of explicit knowledge of their amnesia and overestimated their memory performances. They also expressed higher levels of worry and anxiety than controls, and a more depressed mood. CONCLUSIONS: Although they were aware of their disease state, the TGA patients were unable to identify the nature of their memory deficits and overestimated their memory performances. These memory misperceptions and the inability to acknowledge memory failure occurred concomitantly with changes in the patients' emotional state. This particular pattern of awareness could be regarded as a reaction to the suddenness and massiveness of the amnesia.

Can we remember future actions yet forget the last two minutes? Study in transient global amnesia.

Transient global amnesia (TGA) is a clinical syndrome characterized by the abrupt onset of a massive episodic memory deficit that spares other cognitive functions. If the anterograde dimension is known to be impaired in TGA, researchers have yet to investigate prospective memory (PM)--which involves remembering to perform an intended action at some point in the future--in this syndrome. Furthermore, as executive functions are thought to be spared in this syndrome, TGA provides an opportunity to examine the impact of a massive "pure" memory impairment on PM. We assessed 38 patients with a newly designed protocol that distinguished between the prospective (remembering to do something at the appropriate time) and retrospective (remembering what has to be done) components of PM. Moreover, we investigated episodic memory with an anterograde memory task and assessed executive functions, anxiety and mood, as well as their links with PM. We demonstrated that PM is impaired during TGA, with a greater deficit for the retrospective component than for the prospective component. Furthermore, we highlighted a strong link between these two components. Anterograde episodic memory impairments were correlated with retrospective component deficits in TGA patients, although we were able to confirm that executive functions are globally spared. We discuss this pattern of results within the theoretical framework of PM, putting forward new arguments in favor of the idea that PM deficits can occur mainly because of a massive anterograde memory deficit. The clinical consequences of PM impairment in TGA are examined.

Influence of patients' emotional state on the recovery processes after a transient global amnesia.

INTRODUCTION: Currently, there is no consensus on the delay necessary to a complete recovery after a transient global amnesia (TGA). However, it seems that slight episodic memory disorders extend beyond 24h. Although this impairment is probably a consequence of the TGA attack, other factors such as patients' emotional state can intervene in the slow recovery process. METHODS: In a first experiment, we studied the dynamic of recovery processes after a TGA. Thus, we assessed the anterograde and retrograde components of episodic memory in 19 patients one day, one month and one year after the attack. In a second experiment, we examined the impact of patients' emotional state on memory disorders, in using an original neuropsychological protocol (using material with emotional features) and an assessment of anxiety and depressive mood. This protocol was carried out in 19 other patients examined four months and one year after TGA. RESULTS: In the first experiment, we highlighted mild memory disorders affecting the anterograde component of episodic memory one day after the episode. In the second experiment, we showed these mild memory disorders could be detected several months after TGA. Moreover, patients who had the more depressive tendencies recognized the fewer items and those who displayed the highest level of anxiety supplied the fewer specific remote memories. CONCLUSIONS: Our results showed that patients displayed very mild memory disorders several months after the episode of TGA, not affecting the daily routine. This impairment was influenced by patients' emotional state, which could suggest that a high level of anxiety or depression can slow down the recovery. However, we cannot be sure that the deleterious effect of patients' emotional state on their cognitive performances is specific to TGA. Other investigations are necessary to unravel this issue.

Exploring the roles of the executive and short-term feature-binding functions in retrieval of retrograde autobiographical memories in severe traumatic brain injury.

Conway's autobiographical memory (AM) model postulates that memories are not stored in a crystallised form in long-term memory but are reconstructed at time of retrieval via executive and binding processes, to create a temporary multimodal representation from different AM knowledge. Traumatic brain injury (TBI) impairs AM recollection. However, no study has yet considered the distinct roles of executive and short-term feature-binding functions in the retrieval deficits of retrograde AMs after TBI. Examining a group of 33 TBI patients and 33 controls, our study addresses these roles through a first-ever exploration of the links between performance on an AM verbal fluency evaluation that distinguishes four levels of representation, from semantic to episodic (lifetime periods, general events, specific events, specific details of a specific event), and three executive functions (shifting, inhibition and updating) and two short-term feature-binding functions (short-term formation and maintenance of multimodal representations). The results showed that TBI patients were impaired compared to controls in the retrieval of both semantic and episodic retrograde AM representations, but especially for the most episodic level of AM, in the three executive functions and the short-term maintenance of multimodal representations. Regression analyses indicated that the executive predictors (mainly updating) mediated a large proportion (over 70%) of TBI-related deficit on the retrieval of lifetime periods, general events and specific events, in contrast with the main impairment on generation of specific details which were only mildly (just 12%) predicted by the short-term maintenance of multimodal representations. Additional analyses in a subgroup of patients point to episodic memory abilities and time since injury in predicting the retrieval of specific events and details. In summary, the present study mainly emphasizes that the executive deficits in TBI are involved in the disruption of the first levels of AM generative processes that give access to the multiple episodic details recollection.

Reduced specificity of autobiographical memory and aging: do the executive and feature binding functions of working memory have a role?

Autobiographical memory (AM) is built up from various kinds of knowledge, from general to specific, via generative processes. Aging seems to particularly affect the episodic autobiographical information while preserving information that is more semantic. However, the mechanism of this deficit has not yet been thoroughly tested in relation to working memory. This study is designed to investigate, in a group of 100 subjects, the relationships between age, accessibility to different levels of AM specificity, and two main components of working memory: the central executive and the episodic buffer. We used a new task composed of four embedded verbal autobiographical fluencies (VAF) - from low to highest specificity levels - exploring lifetime periods, general events, specific events, and details, plus tasks exploring free recall of episodic AM and updating, shifting, inhibition, and feature binding in working memory. The results demonstrate that age-related difficulties increase with level of specificity of autobiographical knowledge, i.e., from semantic to episodic aspects. Moreover, regression analyses mainly show that increase in age-related deficit with level of specificity of AM is largely mediated by performance on executive functions (updating and inhibition) and to a lesser extent feature binding in working memory. The results confirm in episodic AM the executive/working memory aging hypothesis, and for the first time highlight the role of episodic buffer in associating the various different details of specific events that elicit the conscious recollection.

Psychopathological factors, memory disorders and transient global amnesia.

BACKGROUND: Some studies have shown the presence of psychopathological disorders in transient global amnesia. AIMS: To determine whether transient global amnesia is associated with psychopathological disorders and to assess the influence of these psychopathological disorders on memory impairments. METHOD: Levels of anxiety and depression before and during transient global amnesia were rated. Memory performances were assessed by means of original episodic memory tasks and working memory tasks. These data were collected in 17 individuals observed during the very acute phase, 18 individuals examined in the peri-acute phase and 26 controls. RESULTS: During the acute phase, participants with transient global amnesia displayed a higher level of anxiety and a more depressed mood than controls. An alteration of emotional state, as measured by the Adjective Mood Scale, was correlated with deficits in anterograde memory. CONCLUSIONS: Transient global amnesia comprises sudden changes in people's emotional state, which has a major impact on and interacts with episodic memory impairment.