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Biomedical subjects

M D Kopelman

Publications and source records attributed to M D Kopelman.

51 records · Page 3Linked to original sources
PubMed1987

Two types of confabulation.

Examples of confabulation in Korsakoff patients, Alzheimer-type dementing patients, and healthy subjects are discussed. It is argued that there may be two types of confabulation: spontaneous confabulation, which may result from the superimposition of frontal dysfunction on an organic amnesia, and provoked confabulation, which may reflect a normal response to a faulty memory. In the present study, instances of provoked confabulation, given by Korsakoff and Alzheimer patients in story recall, were compared with those produced by healthy subjects at a prolonged retention interval.

Adult↗
PubMed1987

Amnesia: organic and psychogenic.

This paper describes the clinical features of selected examples of organic and psychogenic amnesia, and it discusses the nature of the dysfunction that these amnesias entail. The anterograde component of organic amnesia involves a severe impairment in acquiring (or learning) new information, rather than accelerated forgetting, and this may reflect an underlying limbic or neurochemical dysfunction. Retrograde amnesia has a basis which is (at least partially) independent of anterograde amnesia--in some patients, it appears to involve a failure to reconstruct past experience from contextual cues, and this may reflect a super-imposed frontal dysfunction. Two types of confabulation are discussed, one of which ('provoked') is a normal response to poor memory, and the other ('spontaneous') appears to reflect incoherent, context-free retrieval, associated with more severe frontal pathology. It is argued that many cases of psychogenic amnesia may resemble organic amnesia, in that they result from an impaired acquisition of information at the time of initial input, perhaps thereby predisposing the subject to subsequent retrieval difficulties.

Amnesia↗
PubMed1986

Recall of anomalous sentences in dementia and amnesia.

Alzheimer-type dementing patients were compared with amnesic (Korsakoff) patients, depressed patients, and healthy controls in the immediate recall of semantically anomalous sentences. It was found that the dementing (Alzheimer) patients were severely impaired in their recall of these sentences, but that the amnesic (Korsakoff) patients were not. Alzheimer patients have a severe impairment of short-term memory, and it is argued that this deficit may make Alzheimer patients especially dependent upon the presence of semantic cues in immediate verbal recall--hence, the removal or reversibility of these cues results in a collapse of their performance. Other research has indicated that Alzheimer patients also show impaired semantic processing, and the possible interaction of their short-term memory and semantic processing deficits is briefly discussed.

Adult↗
PubMed1986

Clinical tests of memory.

This study compared the performance of groups Alzheimer, Korsakoff, and depressed patients and a group of healthy controls at various clinical tests of memory, and wide differences were found in the discriminatory power of the different tests. In addition, the patterns of performance of the Alzheimer and Korsakoff groups differed, and to some extent this was understandable in terms of what is known about the nature of organic amnesia. Depressed patients showed relatively mild impairments, which were not correlated with the severity of their depression.

Adult↗
PubMed1985

Rates of forgetting in Alzheimer-type dementia and Korsakoff's syndrome.

After initial learning had been equated as closely as possible, 16 Alzheimer-type dementing patients showed the same rate of forgetting on a picture recognition test administered at intervals over the course of a week as 16 Korsakoff patients and 16 healthy controls. This suggested that the anterograde amnesic deficit in both Alzheimer's disease and Korsakoff's syndrome is primarily an acquisition or learning deficit. The Alzheimer patients differed from both the Korsakoff patients and the healthy controls in showing diminished digit span and severely impaired performance at the Brown-Peterson test, implicating a deficit of short-term (or working) memory. The variability of performance within groups on the principal tests employed was also examined; and the Alzheimer results are discussed with respect to the underlying neuropathology, and the implication for pharmacotherapy.

Age Factors↗
PubMed1985

Multiple memory deficits in Alzheimer-type dementia: implications for pharmacotherapy.

This paper investigates the memory disorder of Alzheimer-type dementia by comparing the performance of Alzheimer patients on selected memory tests with that of Korsakoff patients and healthy controls. Alzheimer patients have deficits in both primary and secondary memory, and this finding is compared with that which pharmacological studies predict would occur on the basis of cholinergic depletion. The deficits in primary memory are unlikely to be accounted for in terms of cholinergic depletion, and provide a possible explanation for the disappointing results of trials of cholinergic replacement therapy in this disorder. On the other hand, the pattern of deficit in secondary memory is entirely consistent with that expected from cholinergic depletion.

Adult↗
PubMed1984

Amnesia for criminal offences.

Nearly 10% of a sample of men charged with a variety of offences claimed amnesia for their offence. The amnesia occurred only among those who had committed violence and was most frequent following homicide. All the amnesics had a psychiatric disorder, four having a primary depressive illness and the remainder being almost equally divided between schizophrenia and alcohol abuse. None of the amnesias had any legal implications. The circumstances of the offences suggested a variety of mechanisms to account for the amnesia, including repression, dissociation and alcoholic black-outs. Psychological defence mechanisms were probably of some importance, even when alcohol was an important factor.

Adult↗
PubMed1982

Speech dominance, handedness and electro-convulsions.

This paper discusses methods for assessing speech dominance in cases for unilateral ECT. The use of formal laterality tests has been strongly advocated in the literature, but is seldom adopted in clinical practice. Assessment of handwriting type (left/right, inverted/non-inverted) has been put forward as an alternative, but is not valid. Consideration of handedness alone is the most common practice, but is of little value. From current evidence on the relation of handedness to speech dominance, the paper evaluates the likely outcomes of always administering right-sided ECT, and of giving formal tests to left-handers only.

Dominance, Cerebral↗
PubMedDate not supplied

FDG-PET analysis and findings in amnesia resulting from hypoxia.

The assumptions underlying neuroimaging, and problems in its analysis and interpretation, are commonly underestimated in neuropsychology. The ways in which fluoro-deoxy-glucose (FDG) positron emission tomography (PET) data can be analysed are discussed. PET findings from four patients who had suffered severe amnesia, following episodes of acute hypoxia, are presented. These patients had shown evidence of medial temporal (hippocampal and parahippocampal) atrophy on MRI brain scans. The PET data were analysed in several different ways. The converging findings were that the patients showed bilateral thalamic hypometabolism, and there was also evidence of retrosplenial hypometabolism bilaterally. Cognitively, these patients performed most like other patients with medial temporal lesions, but the results indicate that structural lesions can have distal metabolic effects on structures elsewhere. These findings are interpreted in the light of neuroanatomical observations concerning parallel projections between medial temporal lobe structures and the thalamus, some of which pass via the retrosplenium.

Adult↗