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Presented are current views about memory and memory disturbances. Subsequently, cases of patients are given in whom environmentally-induced stress and trauma situations provoked enduring amnesic conditions in the autobiographic area. It is shown that for many of the patients activity changes can be demonstrated on the brain level, which are evoked by stress and trauma events. Consequently, after the field of neurologically caused, also psychiatrically caused disturbances become available for functional brain imaging.

Cognitive, mnestic, and emotional disturbances can occur in a wide range of psychiatric patients. Both neurochemical alterations as well as structural brain abnormalities can be neural correlates of neuropsychological dysfunctions in these patients. In this paper, we give an introduction to neuropsychological domains with a focus on different kinds of memory and executive functions. Thereafter, we describe neurocognitive deteriorations in patients with schizophrenia, depression, alcohol addiction, and Korsakoff's syndrome. Brain alterations affect primarily parts of the frontal lobe, especially the dorsolateral prefrontal and the orbitofrontal cortex. This can be seen in volume reduction, glucose hypometabolism, or dysfunctions of dopaminergic fronto-striatal loops. Furthermore, structural or functional changes of hippocampal formation, anterior cingulate gyrus, amygdala, and different thalamic nuclei are also involved in neurocognitive disturbances of psychiatric patients.

A differentiation of memory is possible on the basis of chronological and contents-related aspects. Furthermore, it is possible to make process-specific subdivisions (encoding, transfer, consolidation, retrieval). The time-related division on the one hand refers to the general differentiation into short-term and long-term memory, and, on the other, to that between anterograde and retrograde memory ("new" and "old memory"; measured from a given time point, usually that when brain damage occurred). Anterograde memory means the successful encoding and storing of new information; retrograde the ability to retrieve successfully acquired and/or stored information. On the contents-based level, memory can be divided into five basic long-term systems--episodic memory, the knowledge system, perceptual, procedural and the priming form of memory. Neural correlates for these divisions are discussed with special emphasis of the episodic and the knowledge systems, based both on normal individuals and brain-damaged subjects. It is argued that structures of the limbic system are important for encoding of information and for its transfer into long-term memory. For this, two independent, but interacting memory circuits are proposed--one of them controlling and integrating primarily the emotional, and the other primarily the cognitive components of newly incoming information. For information storage principally neocortical structures are regarded as important and for the recall of information from the episodic and semantic memory systems the combined action of portions of prefrontal and anterior temporal regions is regarded as essential. Within this fronto-temporal agglomerate, a moderate hemispheric-specificity is assumed to exist with the right-hemispheric combination being mainly engaged in episodic memory retrieval and the left-hemispheric in that of semantic information. Evidence for this specialization comes from the results from focally brain-damaged patients as well as from that functional brain imaging in normal human subjects. Comparing results from imaging studies in memory disturbed patients with brain damage and from patients with a psychiatric diagnosis (e. g., psychogenic amnesia) revealed that both patient groups demonstrate comparable metabolic changes on the brain level. It can therefore be concluded that in neurological patients distinct, identifiable tissue damage is existent, while in psychiatric patients changes in the brain's biochemistry (release of stress hormones, and transmitters) constitute the physiological bases for the memory disturbances.

For over a century the cerebral representation of language functions is a matter of debate. In Neuroscience language is regarded as one of the most lateralized cognitive functions. Thus, while the language which is acquired first in most cases is processed by the left hemisphere some studies in brain damaged but also experimental investigations propose a pivotal role of the right hemisphere in second language processing. By the advent of modern neuroimaging it is now possible to study language lateralization and bilinguality also in healthy subjects. We studied first and second language abilities in a group of bilingual, healthy individuals by means of functional magnetic resonance imaging (fMRI) with a word-fluency paradigm. While we found a predominantly left prefrontal activity during both first and also second language processing an additional right prefrontal activation was registered during the use of second language. Our findings are discussed on the basis of an interaction between language and memory processes.

The results of neuropsychological-cognitive investigations in patients with obsessive-compulsive disorder are presented in a meta-analysis. The analysis differentiates between intelligence, attention and concentration, memory executive functions, and visual-spatial and visuo-constructive performance. Changes in intelligence are only rarely manifest in obsessive-compulsive patients, and if so, principally in the visuo-constructive field, possibly including abstract-logical processes of thinking. Similarly, they are largely normal in functions of attention and verbal memory; only complex study designs reveal deficits in comparison to control subjects. Obtained deficits in visual memory should be interpreted as being likely due to deficient visuo-perceptive and visuo-constructive performance. Executive functions have not been studied in depth and are unimpaired in most investigations. Visuo-constructive problems are observed most frequently and might best be attributed to problems in Gestalt perception. It has to be pointed out that up to now techniques and designs of investigation are, in the majority of studies, imperfect and that it seems necessary to consider the existence of subgroups of obsessive-compulsive patients with differing degrees of impairment. Prognosis and evaluation of patients with obsessive-compulsive symptomatology depend considerably on their insight into the irrelevance of their behavioural patterns and on the contents of their predominant thoughts and actions. Transferring the deficit patterns to the brain level points to (a) right hemispheric damage and (b) damage in the frontostriatal system.

Patients with Parkinson's disease can suffer from neuropsychological deficits which, in most cases, are already demonstrated at the very beginning (53). Primarily, they are characterized by impairments associated with frontal lobe function affecting psychomotor speed and mental flexibility. Furthermore they show circumscribed impairment of memory functions as well as deficits of visuospatial information processing. Sets of neuropsychological dysfunction of that kind are called subcortical dementia in the American literature. In addition, Parkinson's disease is quite often associated with depressive states which are independent of the neuropsychological deficits. Application of L-Dopa helps to improve the cognitive impairment.

35 multiple sclerosis patients and 30 matched healthy controls were investigated for mnestic problems using a German everyday memory test. The objects were both the description of structural characteristics of disturbances and "ecological validity" to meet rehabilitative issues prospectively. In the MS group, impairments were found mainly in the memory domain under delayed recall conditions of complex material. The processing of these tasks may be especially sensitive against fiber tract lesions. While discrete lesions, mostly found in patients with relapsing-remitting courses, inconsistently lead to partial memory disturbances, global mnestic deficits are to be expected in confluent lesion patterns exceeding a critical "threshold of cerebral tolerance." The latter characterises mostly patients with chronic progressive disease courses.

The maintenance of old memories subsequent to brain damage is discussed with the particular aim of pointing out problems and possibilities of measuring them post-injury. Relationships between forms of brain damage and retrograde amnesia are outlined, and various recent tests designed to measure old memories are specified and assessed. From this survey it is concluded that tests and test batteries are rather heterogenous so far and at best only crudely comparable between studies, and that a clinically practicable (i.e., short), yet valid and reliable test still has to be created.

Older subjects (institutionalized in a home for the aged and non-institutionalized) were compared in a test battery according to the recommendations of the NINCDS-ADRA. The institutionalized subjects were not distinguishable from the controls when only a small amount of information was to be processed or when the information had to be recalled with no distraction. Possible reasons for the observed differences are discussed.

As cognitive deficiencies in aged people constitute a growing factor in our societies, the possibilities for diagnosing dementia are described and analyzed critically. Based on a discussion of those changes in intellectual performance which are typical for normal aging (e.g., reduction in so-called fluid intelligence combined with preservation of so-called crystallized intelligence), the pathological forms of aging, especially Alzheimer's disease, are outlined. The present, internationally favored psychometrical measures for recording dementia in the aged and for evaluating and diagnosing it differentially are listed. Finally, certain requirements which have to be imposed on a diagnostic test for dementia are discussed.