The neuropsychology of hanging: an historical perspective.
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Adult↗
Biomedical subjects
H J Markowitsch
Publications and source records attributed to H J Markowitsch.
[Disordered retrograde memory: diagnostic procedures in brain damage].
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.
Amnesia, Retrograde↗
Complex sensory cross integration deficits in a case of corpus callosum agenesis with bilateral language representation: positron-emission-tomography and neuropsychological findings.
A 45-year-old right-handed patient with total callosal agenesis and absence of the anterior commissure was examined neuropsychologically and with magnetic resonance and positron emission tomography (PET with 18FDG) of the brain. PET results showed, in the resting state, a bilateral metabolic reduction in the hippocampal formation and a left hemispheric reduction in the amygdala, thalamus and in the occipital and temporoparietal junction areas of the cerebral cortex. Under speech activation hypermetabolic glucose activity was observed bilaterally in the region of the Wernicke area and within the left Broca area. Neuropsychologically, on the whole the patient behaved normally, the exceptions being an inability to associate olfactory stimuli with words, a clear left ear advantage in dichotic listening, and a similar high performance in recognizing verbal stimuli presented tachistoscopically to either hemisphere. From comparing the patient's behavior with that of other acallosals it appears that highly individual variants of cerebral organization and/or reorganization result from the lack of the brain's main commissural system and that the processing of sensory information deviates considerably especially in cases in whom the two main telencephalic commissures--corpus callosum and anterior commissure--are absent.
Brain↗
Functional recovery after limbic lesions in monkeys.
Ten monkeys received lesions of either the hippocampus, or the amygdala and hippocampus, or the anterior and medial thalamus (each group with two monkeys), or of all these structures together with additional septal lesions (four monkeys). Postoperatively, the monkeys were trained in tasks of visual and spatial reversal, several concurrent object discriminations, delayed nonmatch-to-sample, and in an angle threshold discrimination task. Their performance was compared to that of five healthy or sham-operated control monkeys. The single- or double-lesioned monkeys were impaired in the delayed nonmatch-to-sample task and the angle threshold discrimination, whereas monkeys with five-fold lesions were unimpaired in these tasks. Correlations between brain volume loss and behavioral performance indicated negative coefficients for the delayed nonmatch-to-sample task ("delays": rs = -.59, "lists": rs = -.20) and the angle threshold discrimination (rs = -.60). It is concluded that monkeys with massive limbic lesions display a more effective postlesion reorganization than monkeys with smaller limbic lesions; however, reliability of this effect must be proved by future work with a larger sample. Furthermore, the missing impairments of massively lesioned monkeys especially in the delayed nonmatch-to-sample task also indicate that the limbic targets lesioned here may not be as exclusively involved in mnemonic information processing as suggested earlier.
Amygdala↗
Verbal memory deterioration after unilateral infarct of the internal capsule in an adolescent.
After an infarction in the territory of the anterior perforating arteries, a 15-year-old, previously healthy, left-handed patient developed considerable verbal long term memory disturbances which could be followed up and tested for more than nine months. An extensive memory test battery was used to determine spared and impaired functions. The patient had remote memory disturbances with respect to personal events for the last 5 years and problems in all verbal task tested which required remembering items over time periods exceeding an hour. The patient was indistinguishable from control subjects on short-term memory tests and on a number of nonverbal learning and recognition tests. The crucial lesion for the observed deficits in the genu of the left internal capsule was assumed to have disrupted the anterior and inferior thalamic peduncles, fornix (column), stria terminalis, anterior commissure and the medial part of the globus pallidus. This infarct, therefore, most likely damaged traversing fibres which intercommunicate within the Papez circuit and the basolateral limbic circuit and which in part provide access to cortical memory representing areas.
Adolescent↗
Diencephalic amnesia: a reorientation towards tracts?
The principal thalamic and hypothalamic structures implicated in mnemonic information processing are the mediodorsal nucleus of the thalamus, the pulvinar, anterior thalamus, and laterodorsal nucleus, the mamillary body, and the mamillothalamic tract and internal medullary lamina. Determining the contribution of an individual region in memory is quite difficult as it is nearly impossible to find a circumscribed damage of only one region. On the contrary, some illnesses affecting primarily the diencephalon, such as Korsakoff's disease, tend to involve several structures together. Furthermore, even when cases with similar circumscribed diencephalic damage can be found, these will not necessarily demonstrate the same outcome on the behavioral level. Therefore, the role or contribution of individual memory-related diencephalic structures has to be inferred by comparing a number of cases and by then extracting distinct features common to a given group. Such an approach revealed that the contributions of the two fiber systems mentioned above, mamillothalamic tract and internal medullary lamina, might be more important in processing information long-term than had been acknowledged previously and might be more important than that of the nuclear masses mentioned, especially of the mediodorsal thalamus. This outcome underlines the view that emphasizing interactions between brain regions rather than single static masses will provide a more realistic picture of how the nervous system acts in information processing.
Amnesia↗
AEV-insular axis: connectivity.
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Animals↗
Cognitive functioning of juveniles with Down syndrome and other forms of mental retardation.
The performance of juvenile Down syndrome individuals and two groups of oligophrenes was compared in several cognitive tests. All three groups of subjects were of the same CA, the Down's and one group of mentally retarded non-Down's had an average MA of 62, the other group an MA of 86 months. Though the group with the highest mental age usually outperformed the other two, significant differences were rare. It is concluded that at this age Down's and mentally retarded with different etiologies generally have rather similar cognitive abilities and that the intellectual deterioration of Down's, which at a later age inevitably leads to Alzheimer's disease, indeed starts only at a later CA.
Adolescent↗
Problems in the differential diagnosis of various forms of transient amnesias.
Definitions and criteria of transient global amnesia (TGA) are described and discussed and related to other forms of transient amnesic attacks. By doing so, possible causes and risk factors for TGA are listed, and TGA is compared with other amnesic states, and differentiating factors are given.
Amnesia↗
Basal forebrain-lesioned monkeys are severely impaired in tasks of association and recognition memory.
Six squirrel monkeys received ibotenic acid-induced lesions targeted to the basal nucleus of Meynert (BNM). Postoperatively, the monkeys were trained in a broad spectrum of learning tasks and compared to normal and sham-operated controls. The lesioned monkeys showed severe and enduring learning and memory deficits in a visual reversal task, several concurrent object discriminations, a delayed nonmatch-to-sample task, and, most outstanding, and angle threshold discrimination. Although in some of the monkeys the BNM was lesioned only partly with some surrounding tissue affected as well, the lesion of the BNM appears to be crucial in the large and apparently irreversible learning deficits of the monkeys. However, final proof for this suggestion is still needed.
Acetylcholinesterase↗
Interactions between damaged brain hemisphere and mode of presentation on the recognition of faces and figures.
Visual recognition performance of right or left hemispheric damaged subjects and of a healthy control group was investigated under three modes of stimulus presentation: normal, sequential, or fragmentary. Stimuli were faces or not easily verbalizable so-called Perret-figures. A dissociation between side of brain damage and performance under sequential vs normal item presentation was found: similar to control subjects, left hemispheric damaged patients remembered previously seen stimuli better under normal presentation, while right brain damaged subjects were superior in performance under sequential compared to normal stimulus presentation. These results may be of relevance for therapeutical interventions with respect to learning and remembering figural material in right brain damaged subjects.
Adult↗
Primate learning tasks reveal strong impairments in patients with presenile or senile dementia of the Alzheimer type.
Eight subjects with the likely diagnosis of presenile or senile dementia of the Alzheimer type were tested on two frequently used primate learning tasks: a concurrent object discrimination task and a delayed non-match-to-sample task. In addition, various tests for cognitive, mnemonic, perceptual, and language functions were applied. The results suggest a severe decline of the Alzheimer subjects in all measures when compared with 10 control subjects matched for age, gender, and education. The two animal learning tasks revealed strong impairments, thus demonstrating a high sensitivity for the detection and assessment of human amnesic disorders. Implications of these findings for human neuropsychological, and especially comparative neuropsychological, research are discussed.
Aged↗
Cortical and subcortical afferent connections of the squirrel monkey's (lateral) premotor cortex: evidence for visual cortical afferents.
The afferent connections of the squirrel monkey's lateral premotor cortex were investigated with the horseradish peroxidase (HRP) technique. Seven monkeys received small, unilateral injections of HRP spaced between the most dorsal and the most lateral region of the premotor cortex. Results are based on six brains, all of which showed a considerable number of labeled neurons both cortically and subcortically. At the cortical level, labeled cells were found both ipsi- and contralateral to the injection site. Heavy labeling occurred in the fields surrounding the prefrontal, central, and precentral cortex, while the temporal regions usually innervated the premotor cortex with a moderate number of cells, and the parietal fields with only a minor number. Surprisingly, in all brains, but especially in those with the more lateral injections, we also found a considerable number of afferents originating from occipital fields, including a few neurons from the striate cortex. Subcortically, a few labeled cells were seen in basal forebrain regions, the amygdala, and the claustrum; a considerable number of thalamic nuclei and also some hypothalamic nuclei contained labeled cells; and within the brainstem, labeling was found most consistently in the locus ceruleus and in the tegmental fields. It is concluded that the (lateral) premotor cortex is involved in sensorimotor integration to a higher degree than has been recognized up to now.
Afferent Pathways↗
Verbal memory in brain damaged patients under different conditions of retrieval aids: a study of frontal, temporal, and diencephalic damaged subjects.
The performance of 36 patients, divided into six groups, and 13 control subjects was investigated in paired-associate learning. The patients had right or left prefrontal, right or left anterior lateral temporopolar or medial temporal lobe damage, or lesions restricted to diencephalic areas. As tasks, two lists of paired words had to be learned, with the first list presenting only the word pairs, and the second one embedding the word pairs in sentences of a highly imaginable content. Recall consisted of immediate or delayed (48 hrs) free recall of the first list (condition I), of immediate or delayed recall of the second list (with visual imagery as a learning aid; condition II), and of cued recall (in which the sentence form was presented with a blank space where the word to be recalled had been previously; condition III). Control subjects clearly performed best under all conditions, manifesting a ceiling effect for the second and third ones under immediate recall. Among the brain-damaged groups the diencephalic subjects were poorest and gained only little from the aids given for learning and recall. Of the four patients with medial temporal lobe damage, those two with bilateral lesions were nearly as bad as the diencephalic lesioned subjects. The other patients were markedly inferior to the control subjects, but gained considerably under conditions II and III. These statements hold for immediate and delayed recall, though for the delayed recall conditions all groups showed a reduction in performance which amounted to roughly half of the values they had had under immediate recall. It is concluded that increasing the possibilities for depth of information processing assists brain damaged (as well as normal) subjects in verbal learning, but that the advantage of aiding them at the moment of encoding and retrieval is highest for patients with restricted lesions and/or with lesions not invading the two regions most regularly implicated in long-term information processing (the diencephalon and the medial temporal lobe area).
Adolescent↗
Single unit activity in cat prefrontal and parietal cortex during performance of a symmetrically reinforced go-no go task.
Relationships between the performance in a symmetrically reinforced go-no go task and cellular firing patterns in prefrontal and parietal association areas of the neocortex were studied in six cats. During recordings, animals lay in a box, with their heads fixed to a stereotaxic frame, and performed an auditory go-no go task by pressing a retractable lever in front of them. Units obtained were classified into eight types according to the correlation of their activity changes with aspects of the task and/or with sensory stimuli. These types were (poly-) sensory, reward related, EMG-related, EOG-related, event-related, movement-initiating, expressing expectancy or novelty, and nonspecific or task-unrelated active units. Between the two recording areas a considerable degree of similarity was obtained in unit firing patterns. It was concluded that within the cerebral cortex, and especially within its association areas, a considerable functional overlap exists, that neurons may be involved in the processing of several and rather different phenomena, and that the processing of information at this level of the brain is generally done via widespread, interwoven neuronal nets so that only the average network activity, but not that of a particular, single neuron, represents a stimulus or an event.
Animals↗
Memory of alcoholic patients, including Korsakoff's, tested with a Brown-Peterson paradigm.
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Adult↗
Cortical projections originating from the cat's insular area and remarks on claustrocortical connections.
The cortical projections originating in the cat's insular cortex and claustrum were investigated with the aid of the horseradish peroxidase retrograde tracing technique. Twenty small injections of horseradish peroxidase were distributed along lateral and medial regions of the hemisphere. Labeling in the insular cortex occurred following all injections except those six situated along the lateral gyrus--that is, within the visual cortex. In the claustrum labeled neurons were found following all injections, except following the injection situated in the posterior temporal area. Claustral labeling was frequently more intense than insular labeling. The injections into the occipital cortex that revealed no insular innervation nevertheless received a considerable number of claustral projections. As the insular cortex itself receives at most a minor projection from the claustrum the differing cortical projection patterns of insula and claustrum have to be considered unrelated. Our findings confirm the view that the claustrum projects to most regions of the cerebral cortex; these projections are at least in part topographically organized. A topographical pattern can also be constructed for the insular cortex, though it is less stringent than for the claustrocortical connections. Both the afferent and efferent connections of the insula show similarities to those of the prefrontal cortex. Nevertheless, the insula differs in that it receives strong input from the sensory associative nuclei of the thalamus. Consequently, and in line with behavioral observations following its ablation, we consider the insula as involved in the temporal structuring of perceived patterns.
Animals↗
Korsakoff and alcoholic subjects are severely impaired in animal tasks of associative memory.
Korsakoff subjects, members of the Alcoholics Anonymous, and alcoholics with 1 week or 5-6 months of abstinence were tested in a concurrent object discrimination task with 10 and 20 pairs of objects and compared to control subjects matched for age and education. The anonymous alcoholics were moderately Korsakoff subjects strongly impaired, whereas alcoholics with 1 week or 5-6 months abstinence performed similar to control subjects. The results are discussed with respect to current research on human amnesia and comparative neuropsychological topics.
Adult↗