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Zusammenfassung. Dissoziative Amnesie verläuft unter Umständen chronisch und kann zu lebenslanger Arbeitsunfähigkeit führen. Die Krankheit tritt gehäuft im Zusammenhang mit Migration auf und verläuft dann schwerer als in anderen Fällen. Sie ist im Grunde reversibel, d. h., der Abruf der Gedächtnisinhalte ist nur blockiert. Betroffen sind Patienten, die nicht verarbeitete Stress- und Traumaerlebnisse als Hintergrund haben und dann ein erneutes Stresserlebnis erfahren, welches zum dissoziativen Amnesiezustand führt. Es wird postuliert, dass in erster Linie Patienten betroffen sind, die im neuen Heimatland nicht ausreichend und ihrem Anspruch entsprechend Fuß fassen konnten. Mangelnde Sprachkenntnisse und eine nicht den Erwartungen entsprechende neue Arbeitssituation sind am ehesten als Gründe anzuführen.

The term 'episodic memory' was coined by Endel Tulving, who also created a classification in several memory systems. This classification is presented, and it is described which predecessors existed for the partition of memory into systems. The 'episodic memory system' is discussed as being in general equivalent with the 'episodic-autobiographical memory system'. It is seen as an emotionally colorized system. A special paragraph is devoted to the 'perceptual memory system', as this was not included in Tulving's previous schemes of memory systems. More recent sub-categorizations of the 'episodic memory system' are presented and a perspective on the future of the episodic memory system is developed.

Memory disorders without a direct neural substrate still belong to the riddles in neuroscience. Although they were for a while dissociated from research and clinical arenas, risking becoming forgotten diseases, they sparked novel interests, paralleling the refinements in functional neuroimaging and neuropsychology. Although Endel Tulving has not fully embarked himself on exploring this field, he had published at least one article on functional amnesia (Schacter et al., 1982) and ignited a seminal article on amnesia with mixed etiology (Craver et al., 2014). Most importantly, the research of Endel Tulving has provided the researchers and clinicians in the field of dissociative or functional amnesia with the best framework for superiorly understanding these disorders through the lens of his evolving concept of episodic memory and five long term memory systems classification, which he developed and advanced. Herein we use the classification of long-term memory systems of Endel Tulving as well as his concepts and views on autonoetic consciousness, relationships between memory systems and relationship between episodic memory and emotion to describe six cases of dissociative amnesia that put a challenge for researchers and clinicians due to their atypicality. We then discuss their possible triggering and maintaining mechanisms, pointing to their clinical heterogeneity and multifaceted causally explanatory frameworks.

The memory impairment of neurological and psychiatric patients is seen as occurring mainly in the autobiographical-episodic memory domain and this is considered to depend on limbic structures such as the amygdala or the septal nuclei. Especially the amygdala is a hub for giving an emotional flavor to personal memories. Bastin et al. fail to include the amygdala in their integrative memory model.

Dissociative disorders are heterogeneous with respect to clinical features, course, antecedents and treatment. Among them, dissociative amnesia occupies a special place, at times encroaching on the borders between neurology and psychiatry. Herein we describe dissociative amnesia according to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders and outline data on its epidemiology, neurobiology, neuroimaging, clinical and differential diagnosis, neuropsychology, comorbidities, prognosis, treatment and rehabilitation. To enable a neuroscientific approach to its diagnosis, we outline the memory division into short-term and long-term memory, elaborating on the content-based classification of the long-term memory systems. Dissociative amnesia most commonly manifests itself in its retrograde variants (including dissociative fugue), but anterograde variants can also occur. Dissociative amnesia may be overlooked when it occurs on a background of mixed antecedents and comorbidities. Comprehensive neuropsychological assessment – including tests tapping on all memory systems and symptom validity tests – is still insufficiently integrated in the clinical practice, although it could aid in securing an accurate diagnosis, especially in cases with mixed antecedents or concomitant forensic or litigation backgrounds. Presently there is a paucity of treatment and rehabilitation methods for dissociative amnesia. Developing research evidence-based consensus guidelines for diagnosis and treatment is an essential goal. This review contains 6 figures, 7 tables, and 60 references. Key Words : consciousness, episodic-autobiographical memory, mnestic block syndrome, neuroimaging, serial-parallel-independent model, personal identity, stressful life events, malingering, trauma, feigning

Autobiographical amnesia is found in patients with focal or diffuse brain damage ("organic amnesia"), but also without overt brain damage (at least when measured with conventional brain imaging methods). This last condition is usually named dissociative amnesia at present, and was originally described as hysteria. Classically and traditionally, dissociative amnesia is seen as a disorder that causes retrograde amnesia in the autobiographical domain in the aftermath of incidents of major psychological stress or trauma. In the present study one of the probably largest published collections of patients (28) with psychogenically caused autobiographical amnesia, who were assessed with comprehensive neuropsychological tests, will be described and documented in order to identify variables which are central for the occurrence of dissociative amnesia. The presented cases demonstrate that autobiographical amnesia without direct brain damage can have very mixed clinical presentations, causes and consequences. The described cases of psychogenic amnesia are clustered according to a number of manifestations and features, which include a reduced effort to perform cognitively at a normal level, a forensic background, anterograde (instead of retrograde) autobiographical amnesia, the fugue condition, concurrent somatic diseases, and their appearance in childhood and youth. It is concluded that autobiographical amnesia of a psychogenic origin may occur within a variety of symptom pictures. For all patients, it probably serves a protective function by offering them a mechanism to exit a life situation which appears to them unmanageable or adverse.

The historical roots of memory research—mainly from the period between 1870 and 1920—are described with emphasis on human memory. First, data from experimental psychology are reviewed; thereafter principal contributions from the old traditions of psychiatry and psychoanalysis are given and then relations between brain tissue damage and memory deficits are outlined. Experimental as well as clinical studies of that time already provided evidence for theoretical ideas on memory systems, which resemble those en vogue today. Furthermore, significant and still valid findings were reported on the contribution of bottleneck structures of the limbic system for mempry encoding. Among these, the mammillary bodies, thalamic nuclei, and the medial temporal lobe were most consistently mentioned. Furthermore, early findings from psychiatric patients revealed similar forms of dissociative states as found presently and indicated that these disease conditions occur much more in young than in older adults.

Violence is a ubiquitous phenomenon, which has been part of the experience of humanity since its inception. Violence has classically been viewed as being associated with being male. In general population, men are reported to commit violent acts significantly more frequently than women. As the interdisciplinary research data point to, violence is a complex phenomenon that could be approached from different perspectives, such as social, economic, political, religious, biological, and genetic. We hereby provide a review of the neurobiological mechanisms underlying the gender distinctions in violence and aggression in both general and psychiatric population.

Environmentally induced stress may lead to a phenomenon termed ‘mnestic block syndrome’. The memory changes primarily affect the patient's autobiography by either blocking the retrieval of old memories, or by impairing the formation of new memories. We studied patients with either form of amnesia neuropsychologically and with functional imaging methods. We obtained a right temporo-frontal hypometabolism in patients with psychogenic amnesia, restricted to their autobiography. We conclude that environmentally induced brain changes are due to the action of stress hormones leading to a block of memory-related information flow in the brain which can persist over decades.

Brain damage was traditionally seen as the product of a neurological disease or injury. Nevertheless, modern brain imaging techniques have provided increasing evidence for alterations in brain tissue and metabolism for a number of psychiatric disorders. Though for a while “dissociated” ( Spiegel, 2006 ) from the clinical and scientific arena, dissociative disorders have in the last several years received a renewed interest among several groups of researchers, who embarked on the work of disentangling their neural correlates. We review data from our own research as well as others, which point to distinct changes in brain regions underlying dissociative amnes(t)ic disorders. These changes may consist of overall reductions in brain metabolism or more selective alterations primarily in the right temporo-frontal cortices. Recent evidence with refined magnetic resonance imaging techniques furthermore reveals selective fiber degenerations in these regions. While these changes may persist and probably even intensify in some patients, they may be reversible in others – especially if treatment is carried out successfully within short time after onset. Implications of these findings for the pathogenetic conceptualization of dissociative amnes(t)ic disorders are outlined.

Lindquist et al. remark that not all fear instances lead to heightened amygdalar activity and, instead, point to roles of the amygdala in detecting “motivationally salient “or “emotionally impactful” stimuli. By reviewing research on the amygdala's functions in episodic-autobiographical memory, we further emphasize the involvement of the amygdala in coding the subjective relevance and extracting the biological and social significance of the stimuli.

Lane et al. view the process of memory reconsolidation as a main ingredient of psychotherapeutic change. They ascertain that in cognitive behavioral therapy (CBT) high priority is given to the “semantic structure.” We argue that memory-related mechanisms of change in CBT are more nuanced than the target article presents. Furthermore, we propose to partially shift the focus from the process of reconsolidation to the retrieval operations.

Learning is described as a universal attribute of animals that is accompanied by diverse changes in the nervous system. On the brain level, memory is seen as being represented in distributed neural networks. On the behavioral level, memory is seen as divided along a time- and a content-based axis (short-term, working, long-term memory; procedural memory, priming, perceptual and semantic memory (knowledge system), and episodic-autobiographical memory). Neurological and psychiatric disease conditions can be used to determine brain regions that act as bottleneck structures in information processing.

It is argued that Llewellyn's hypothesis about the lack of rapid eye movement (REM)-sleep dreaming leading to loss of personal identity and deficits in episodic memory, affectivity, and prospection is insufficiently grounded because it does not integrate data from neurodevelopmental studies and makes reference to an outdated definition of episodic memory.

Introduction: Functional amnesia refers to various forms of amnesia, which have no direct organic brain basis. Psychological stress and trauma were etiologically linked to its development across various cultures. Methods: We have studied several patients With functional amnesia, employing neuropsychological and neuroimaging methods. Herein we provide a review of the current understanding of the phenomenology, neuropsychology and neurobiology of functional amnesia, which we illustrate by reference to five own case descriptions and other cases presented in the literature. Results: Functional amnesia is mostly of retrograde nature and presents in the form of a memory blockade or repression to recollect episodic-autobiographical events, which may cover the whole past life. Sometimes, the recollection impairment is localized to certain time epochs. In comparison to functional retrograde amnesia, functional isolated anterograde amnesia is much rarer and data on its neurobiology are scant. In patients with functional amnesia with pronounced retrograde episodic-autobiographical memory impairments, we identified changes in brain metabolism, above all reductions in the temporo-frontal regions of the right hemisphere. Recently, even subtle structural changes in the white matter of the (right) frontal cortex were described in functional retrograde amnesia by other researchers Conclusions: The disruption in recollection in functional amnesia is often accompanied by changes in personality dimensions, pertaining to cognition (self-related processing, theory of mind), autonoetic consciousness and affectivity. This suggests that functional amnesia is a multifaceted condition. We hypothesize that the recollection deficit in functional retrograde amnesia primarily reflects a desynchronization between a frontal lobe system, important for autonoetic consciousness, and a temporo-amygdalar system, important for evaluation and emotions. Despite assumptions that functional amnesia can always be reversed, several cases of functional amnesia were found to follow a chronic course, suggesting a need for longitudinal prospective studies to quantify possible global cognitive deterioration over time and its neural underpinnings. (C) 2012 Elsevier Ltd. All rights reserved.

Remembering the past is a core feature of human beings, enabling them to maintain a sense of wholeness and identity and preparing them for the demands of the future. Forgetting operates in a dynamic neural connection with remembering, allowing the elimination of unnecessary or irrelevant information overload and decreasing interference. Stress and traumatic experiences could affect this connection, resulting in memory disturbances, such as functional amnesia. An overview of clinical, epidemiological, neuropsychological, and neurobiological aspects of functional amnesia is presented, by preponderantly resorting to own data from patients with functional amnesia. Patients were investigated medically, neuropsychologically, and neuroradiologically. A detailed report of a new case is included to illustrate the challenges posed by making an accurate differential diagnosis of functional amnesia, a condition that may encroach on the boundaries between psychiatry and neurology. Several mechanisms may play a role in “forgetting” in functional amnesia, such as retrieval impairments, consolidating defects, motivated forgetting, deficits in binding and reassembling details of the past, deficits in establishing a first person autonoetic connection with personal events, and loss of information. In a substantial number of patients, we observed a synchronization abnormality between a frontal lobe system, important for autonoetic consciousness, and a temporo-amygdalar system, important for evaluation and emotions, which provides empirical support for an underlying mechanism of dissociation (a failure of integration between cognition and emotion). This observation suggests a mnestic blockade in functional amnesia that is triggered by psychological or environmental stress and is underpinned by a stress hormone mediated synchronization abnormality during retrieval between processing of affect-laden events and fact-processing.

Memory is not a unity, but is divided along a content axis and a time axis, respectively. Along the content dimension, five long-term memory systems are described, according to their hierarchical ontogenetic and phylogenetic organization. These memory systems are assumed to be accompanied by different levels of consciousness. While encoding is based on a hierarchical arrangement of memory systems from procedural to episodic-autobiographical memory, retrieval allows independence in the sense that no matter how information is encoded, it can be retrieved in any memory system. Thus, we illustrate the relations between various long-term memory systems by reviewing the spectrum of abnormalities in mnemonic processing that may arise in the dissociative amnesia—a condition that is usually characterized by a retrieval blockade of episodic-autobiographical memories and occurs in the context of psychological trauma, without evidence of brain damage on conventional structural imaging. Furthermore, we comment on the functions of implicit memories in guiding and even adaptively molding the behavior of patients with dissociative amnesia and preserving, in the absence of autonoetic consciousness, the so-called “internal coherence of life”.

Memory and time have multifaceted links. Along the time axis, memory is divided into short- and long-term memory. Another popular time-dependent distinction is between new and old memories and anterograde and retrograde memory impairments, respectively. Time-embedment characterizes the processing of mnemonic information, which encompasses the stages of registration, encoding, consolidation, and storage. Along the content axis, memory is partitioned into five long-term memory systems (procedural, priming, perceptual, semantic, and episodic), which are regarded to build up on each other from both a phylogenetic and ontogenetic perspective. These memory systems are accompanied by different niveaus of self and levels of consciousness. Among these long-term memory systems, the episodic memory system holds a special connection with time, which we aim to detail. In 2005, Tulving defined the episodic memory system as the conjunction of subjective time, autonoetic consciousness, and the experiencing self. Drawing on this last definition of the episodic memory, which lays an emphasis on the linkage to the self, Markowitsch has subsequently promoted the use of the construct “episodic-autobiographical” memory system. The episodic-autobiographical memory system features mental time travelling, an essential property that enables one individual to flexibly travel in subjective time in his/her past and, in addition, to flexibly project him/herself in the future. This property provides a “glue” for the self, supporting a coherent view of one's own person. According to Tulving and Markowitsch, it is unlikely that non-human animals possess the capacity for mental time travelling and the ability to “look into future” (“proscopy”). Furthermore, Tulving and Markowitsch had proposed that the ability for mental time travelling is dependent on age and intellect. Subsequent studies have confirmed that mental time travelling is one of the last features of the episodic- autobiographical memory system that achieves full functionality in humans and is the first one to be afflicted by old age, amnesia or neurodegenerative dementias (e.g., Alzheimer's dementia). At the brain level, the emergence of the capacity for mental time travelling is accompanied by ample structural and functional reorganization of elements of the brain networks supporting episodic-autobiographical memory, autonoetic consciousness, and self-referential processing. In human beings, damage to certain brain regions may alter the sense and consciousness of time in quite different ways. Herein, we have the goal to review changes in time perception and consciousness of time, which accompany different forms of amnesia. Patients with anterograde amnesia manifest an inability to consciously acquire new information for long-term storage and as a consequence are often “stuck in time”. ‘Chronotaraxis’ may accompany certain forms of preponderantly anterograde amnesia, as we aim to exemplify by drawing upon own cases, which were investigated medically, neuropsychologically, and with neuroimaging methods. Patients with retrograde amnesia manifest an inability to consciously retrieve already stored old mnemonic information, usually from the episodic-autobiographical memory domain. They lack the capacity to “ecphorize” old memories. Interestingly, the memory impairments are very similar in the patients with focal traumatic brain injuries and in those with psychogenic forms of amnesia: The patients are unable to engage in mental time traveling into their past. In addition, they show an impaired ability to imagine future personal events, being as a consequence trapped in a “noetic existence”. In psychogenic amnesia with pronounced retrograde memory impairments, we found (via functional neuroimaging) evidence of defective synchronization during retrieval between processing of affectively loaded personal events (that is presumed to preponderantly engage the right hemisphere) and fact-based processing (that is considered to preferentially recruit the left hemisphere). These data are relevant in the light of studies pointing to a right hemisphere bias for higher forms of consciousness. We conjecture that this synchronization abnormality not only leads to a memory blockade, but also to shrinkage of mental time traveling and loss of autonoetic consciousness in psychogenic or functional amnesic conditions.

The human amygdala is strongly embedded in numerous other structures of the limbic system, but is also a hub for a multitude of other brain regions it is connected with. Its major involvement in various kinds of integrative sensory and emotional functions makes it a cornerstone for self-relevant biological and social appraisals of the environment and consequently also for the processing of autobiographical events. Given its contribution to the integration of emotion, perception and cognition (including memory for past autobiographical events) the amygdala also forges the establishment and maintenance of an integrated self. Damage or disturbances of amygdalar connectivity may therefore lead to disconnection syndromes, in which the synchronous processing of affective and cognitive aspects of memory is impaired. We will provide support for this thesis by reviewing data from patients with a rare experiment of nature - Urbach-Wiethe disease - as well as other conditions associated with amygdala abnormalities. With respect to memory processing, we propose that the amygdala's role is to charge cues so that mnemonic events of a specific emotional significance can be successfully searched within the appropriate neural nets and re-activated.

A substantial proportion of the recently published cases of dissociative disorders have a background of immigration (Fujiwara et al., 2008). Among the dissociative disorders, Ganser syndrome is an uncommon form that has as central symptom the giving of approximate answers to questions (vorbeireden). The predisposing and triggering factors of Ganser syndrome are poorly defined. Furthermore, this condition might cooccur with other psychiatric disorders. Here we describe a patient with a background of immigration, who, after an objectively minor work-related head injury, developed severe and persistent psychiatric symptoms, with features of Ganser syndrome.The patient was assessed medically, psychiatrically, and by neuropsychological testing.The patient is a man with no known previous psychiatric history, who lived in several countries and encountered a series of stressful experiences in the process of migration. Several years after immigrating to his current country of residency, he developed severe psychiatric symptoms of Major Depressive Disorder, with Psychotic Features and Ganser syndrome. The symptoms, which emerged after a mild head injury, have persisted for more than a year, despite treatment.The similarity between this case and other reports suggests that psychosocial stresses accompanying immigration may have a catalytic effect in triggering and maintaining dissociative symptomatology.

As psychiatric illnesses have correlates in the brain, it is surprising that Cramer et al. make almost no reference to the brain's network character when proposing a network approach to comorbidity of psychiatric diseases. We illustrate how data from combined neuropsychological and functional and structural brain-imaging investigations could inform theoretical models about the role played by overlapping symptoms in the etiology of psychiatric comorbidity and the pathways from one disorder to another.

Introduction Dissociative amnesia is triggered by psychological stress or trauma. Its hallmark is a severe (usually retrograde) memory impairment within episodic-autobiographical domain, occurring without evidence of significant brain damage on conventional structural brain imaging. Objectives This work’s objectives are establishing greater recognition of possible relations between memory performance and social cognition in patients with dissociative amnesia. Aims We review data on social cognition (affective and cognitive theory of mind, simulation, empathy, social judgment, moral judgment) from our own patients with dissociative amnesia. Methods Patients were investigated medically, psychiatrically and with neuropsychological and neuroimaging methods. Results Patients with dissociative amnesia show variable degrees of impairments of components of social cognition, based on their comorbid conditions (e.g. concurrent clinical or subclinical depression), types of memory impairments (e.g. extent of retrograde amnesia, presence of autobiographical semantic deficits), pattern of brain metabolic changes, personality characteristics, neuropsychological profile (performance on executive functions or emotional processing) and testing paradigms. Conclusions The impairment in dissociative amnesia seems to go beyond the conscious mnemonic deficit, encompassing various aspects of social information processing. Knowledge about the pattern of metabolic and micro-structural brain changes in patients with dissociative amnesia as well as a fine-grained analysis of the neural correlates of various aspects of social cognition might provide an understanding of when and how episodic-autobiographical memory contributes to social cognition. As several studies emphasized, some structures involved in mnemonic processing may also play a role in social perception, cognition and behavioural regulation, including future-minded choice behaviour.

Introduction Co-occurring impairments of episodic-autobiographical memory and theory of mind were described in several psychiatric and neuropsychiatric disorders. Despite sophisticated elaborations in theoretical domains, the relationship between episodic-autobiographical memory and social cognition remains unelucidated. Objectives This work’s objectives are establishing greater recognition of the possible contribution of episodic - autobiographical memory to social cognition, by resorting to data from developmental amnesia (a condition with onset in early childhood, caused by relatively selective bilateral damage to hippocampi). Aims We describe a young adult with amnesia with neurodevelopmental mechanisms. Methods The patient was investigated medically, psychiatrically, with extensive neuropsychological methods and with neuroimaging. Results Neuroimaging revealed grossly reduced hippocampi volumes bilaterally. There was no evidence of pathology in the underlying parahippocampal region or other areas. Performance on tasks that tapped on various aspects of social cognition was non-uniform, ranging from within normal limits to moderate impairment. Conclusions According to our knowledge, this is among the first case reports about a comprehensive evaluation of social information processing in a patient with amnesia with neurodevelopmental mechanisms. This patient showed impairments in performance in some laboratory tasks for social cognition, but not in others. This suggests that various components of social cognition may have different neural correlates; their unraveling may aid understanding of when and how episodicautobiographical memory contributes to social cognition. This study also emphasizes the need to employ various tasks to assess social cognition in patients with amnesia, which go beyond traditional laboratory paradigms.

Dissociative memory disturbances characterize dissociative disorders (such as dissociative amnesia, dissociative fugue, dissociative identity disorder, Ganser syndrome) and certain anxiety disorders (post-traumatic stress disorder). Across various cultures, they are recognized to be precipitated by psychological stress. In immigrant populations, stressful experiences arising during migration and acculturation could lead to somatic and psychiatric symptoms (including dissociative ones). A delayed onset of these symptoms - that at times occurs - may reflect a kindling sensitization or an incubation effect.ObjectivesWe review four patients who developed Dissociative Disorders (Dissociative Amnesia and Ganser Syndrome) on a background of stresses related to immigration.MethodsPatients were investigated medically, psychiatrically and neuropsychologically and in part neuroradiologically.ResultsPatients were adult males with Eastern or Central European background and no known previous psychiatric or medical illnesses. They immigrated to Germany or Canada and encountered several difficulties in the process of migration or adaptation to the new country. All developed severe psychiatric dissociative symptoms after objectively minor stresses, which occurred several years after their immigration to the new country of residence. Despite adequate treatment, their symptoms followed a chronic course. The patients’ neuropsychological profiles shared similarities, such as executive functioning deficits (e.g. limited cognitive flexibility) and impairments of emotional processing in addition to severe autobiographical amnesia.ConclusionsWe propose that stresses related to immigration and acculturation could trigger dissociative memory disorders in immigrants via a dysregulation of the hormonal stress responses, which is mediated by individual characteristics (cognitive flexibility, emotional processing abilities, language competence and cultural affiliations).