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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.

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.

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.