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Michael D Kopelman

Publications and source records attributed to Michael D Kopelman.

13 recordsLinked to original sources
PubMed2006

Recall and recognition memory in amnesia: patients with hippocampal, medial temporal, temporal lobe or frontal pathology.

The relationship between recall and recognition memory impairments was examined in memory-disordered patients with either hippocampal, medial temporal, more widespread temporal lobe or frontal pathology. The Hirst [Hirst, W., Johnson, M. K., Phelps, E. A., & Volpe, B. T. (1988). More on recognition and recall in amnesics. Journal of Experimental Psychology: Learning, Memory, & Cognition, 14, 758-762] technique for titrating exposure times was used to match recognition memory performance as closely as possible before comparing recall memory scores. Data were available from two different control groups given differing exposure times. Each of the patient groups showed poorer recall memory performance than recognition scores, proportionate to the difference seen in healthy participants. When patients' scores were converted to Z-scores, there was no significant difference between mean Z-recall and Z-recognition scores. When plotted on a scatterplot, the majority of the data-points indicating disproportionately low recall memory scores came from healthy controls or patients with pathology extending into the lateral temporal lobes, rather than from patients with pathology confined to the medial temporal lobes. Patients with atrophy extending into the parahippocampal gyrus (H+) performed worse than patients with atrophy confined to the hippocampi (H-); but, when H- patients were given a shorter exposure time (5s) and compared with H+ at a longer exposure (10s), their performance was virtually identical and did not indicate any disproportionate recall memory impairment in the H- group. Parahippocampal volumes on MRI correlated significantly with both recall and recognition memory. The possibility that findings were confounded by inter-stimulus artefacts was examined and rejected. These findings argue against the view that hippocampal amnesia or memory disorders in general are typically characterised by a disproportionate impairment in recall memory. Disproportionate recall memory impairment has been observed in a number of published cases, and the reason for the varying pattern obtained across hippocampal patients requires further examination.

Adult↗
PubMed2005

Correlations of regional cerebral metabolism with memory performance and executive function in patients with herpes encephalitis or frontal lobe lesions.

Cerebral [18F]fluorodeoxyglucose positron emission tomography (18FDG-PET) data from patients suffering amnesia following herpes encephalitis (n=7) or frontal lobe pathology (n=14) were compared with data from age-matched nonamnesic subjects (n=10). All subjects received structural MRI, resting 18FDG-PET scans, and neuropsychological evaluation. PET data were analyzed using complementary statistical parametric mapping and region-of-interest methods. Differential patterns of hypometabolism were found in patients relative to healthy controls. Factor analysis of the neuropsychological data revealed that memory performance was associated with retrosplenial and medial temporal metabolism, and executive function was associated with dorsolateral frontal metabolism. The association between memory performance and retrosplenial metabolism remained statistically significant after accounting for measures of cerebral atrophy using MRI. The significance of the retrosplenium as a major relay station between the thalamus and the medial temporal and frontal lobes--sensitive to changes in either--is discussed in the light of the findings.

Adult↗
PubMed2004

Remembering and forgetting of semantic knowledge in amnesia: a 16-year follow-up investigation of RFR.

We report our long-term follow-up investigations of RFR, a post-encephalitic case of very grave anterograde and retrograde amnesia. We also describe the results of quantitative neuroimaging of his brain injury that showed bilateral and severe reduction in the hippocampal formation and medial temporal structures with sparing of left lateral/posterior and right posterior temporal cortex. We established that RFR had a persistent severe anterograde and retrograde amnesia for personal and public events. His personal semantic knowledge was relatively spared for the retrograde period. There was a modest and global reduction in RFR's vocabulary for words acquired in adulthood before he became amnesic but there was no evidence of any retrograde gradient. His retrograde knowledge of people was also without any gradient. Remarkably, there had been no change in the extent of his semantic knowledge across a prolonged re-test interval indicating that the loss of semantic knowledge was stable and likely to have arisen at the time of his initial lesion. RFR also showed evidence of a limited but significant ability to acquire new word meanings and a more restricted capacity for learning about new celebrities. While he was able to demonstrate face and name familiarity for newly famous people, he was unable to provide much semantic detail. RFR's amnesia can be partially explained by contemporary theories that allow for parallel cortical and hippocampal memory systems but is difficult to reconcile in detail with any extant view.

Aged↗
PubMed2003

Coexistence of posttraumatic stress disorder and traumatic brain injury: towards a resolution of the paradox.

The coexistence of posttraumatic stress disorder (PTSD) and traumatic head or brain injury (TBI) in the same individual has been proposed to be paradoxical. It has been argued that individuals who sustain a TBI and have no conscious memory of their trauma will not experience fear, helplessness and horror during the trauma, nor will they develop reexperiencing symptoms or establish the negative associations that underlie avoidance symptoms. However, single case reports and incidence studies suggest that PTSD can be diagnosed following TBI. We highlight critical issues in assessment, definitions, and research methods, and propose two possible resolutions of the paradox. One resolution focuses on ambiguity in the criteria for diagnosing PTSD. The other involves accepting that TBI patients do experience similar symptoms to other PTSD patients, but that there are crucial differences in symptom content.

Acute Disease↗
PubMed2003

Advanced brain imaging procedures and human memory disorder.

The impact of advanced brain imaging procedures in the field of human memory disorder is reviewed, with particular emphasis on current and potential applications that may impact upon the diagnosis and management of memory-disordered patients. While both advanced structural, resting physiological and functional physiological brain imaging procedures have been applied to conditions where memory disorder is a major feature, the specific implications of research findings for diagnosis and treatment in routine clinical practice remain tentative and promising, but not yet substantive enough to inform clinical decisions to a significant degree. In terms of diagnostic applications, several promising areas include dementia, epilepsy, and transient amnesic states. In the case of applications in treatment settings, advanced brain imaging procedures may help to monitor neural correlates of spontaneous recovery or progression of memory function, and may also help in the planning and monitoring of therapeutic intervention.

Brain↗
PubMed2002

Contribution of recollection and familiarity judgements to rate of forgetting in organic amnesia.

The present study sought to determine whether the rate of forgetting in amnesic and control participants varied as the relative contribution of familiarity judgements (or implicit memory) was manipulated. In Experiment 1, rates of forgetting were measured in two recognition conditions in which the relative contribution of familiarity judgements and recollection had been manipulated. No significant group by condition or group by condition by delay effects were found. In Experiment 2, we compared word recognition and word recall tasks on the assumption that this would produce a larger difference in the role of familiarity judgements versus recollection. In this case, we did obtain a significant difference in forgetting rates, the amnesic patients forgetting faster than the healthy subjects in the recall condition. In summary, amnesic patients showed faster forgetting on recall than recognition, which we have attributed to the absence of the opportunity for familiarity judgments in recall testing. We concluded that amnesic patients show a primary deficit in the acquisition of new information (with associated or secondary retrieval deficits), and that, in addition, they show a deficit in long-term retention detectable only on recall ('high recollection') testing.

Adult↗
PubMed2002

The National Adult Reading Test as a measure of premorbid intelligence: a comparison with estimates derived from demographic variables.

Since its publication in 1982, the National Adult Reading Test (NART; Revised Version, NART-R) has become a widely accepted method for estimating premorbid levels of intelligence in neuropsychological research. However, the assumption that NART/NART-R performance is relatively independent of brain damage has been increasingly challenged in recent years. In a number of conditions, including Alzheimer dementia and Korsakoff's syndrome, studies have indicated a deterioration in reading ability, leading to an underestimated premorbid IQ. In a reaction to these studies, some researchers have advocated the use of demographic variables as a more suitable foundation for accurately predicting premorbid intelligence. We addressed this issue by calculating IQ estimates on the basis of NART/NART-R, demographic variables, and a combination of the two approaches and by comparing these with current WAIS/WAIS-R IQ in patients with Korsakoff's syndrome, Alzheimer dementia, frontal or temporal lobe lesions, and in healthy controls. Estimated premorbid IQs did not differ across groups, whether derived from NART/NART-R or demographic variables. Those based on NART/NART-R demonstrated higher correlations with current WAIS/WAIS-R IQ in controls and patients than those derived from demographic variables. An equation combining NART scores with demographic variables did not significantly increase the amount of variance in IQ explained by NART only, either in patients or controls. The data offer reassurance regarding the continued use of NART as a valid estimate of premorbid intelligence in a number of conditions.

Alzheimer Disease↗
PubMed2002

Disorders of memory.

This paper reviews disorders of memory. After a brief survey of the clinical varieties of the amnesic syndrome, transient and persistent, selected theoretical issues will be considered by posing a series of questions. (i) What is impaired and what is spared in anterograde amnesia? (ii) Do temporal lobe, diencephalic and frontal lobe amnesias differ? (iii) How independently semantic is semantic memory? (iv) What determines the pattern and extent of retrograde memory loss? (v) Can retrograde amnesia ever be "isolated"? (vi) Does psychogenic amnesia involve the same mechanisms as organic amnesia? (vii) How and when do false memories arise? Commonalities as well as differences across separate literatures will be emphasized, and the case for a more "dynamic" (interactionist) approach to the investigation of amnesia will be advocated.

Amnesia↗
PubMed2002

Subcortical dementia.

BACKGROUND: Drawing a distinction between cortical and subcortical dementias seems both useful and justified. Recent research has, however, cast doubt on the clinical, neuropsychological, neuroimaging and neuroanatomical basis of the distinction. AIMS: To arrive at a reasoned conclusion about the relationship between the two types of dementia and the validity of distinguishing between them. METHOD: The historical and recent clinical and scientific literature on subcortical dementia was reviewed. RESULTS: The traditional claim that subcortical dementia has distinct clinical manifestations, neuroimaging findings and a neuropathological profile is not altogether borne out by the literature. Some studies show that frontal executive dysfunction and the profile of memory deficits are not significantly different from those seen in Alzheimer's disease. Neuropathological findings also overlap. CONCLUSIONS: The category of subcortical dementia may be clinically useful in highlighting the likelihood that an individual with dementia is more likely to suffer from bradyphrenia and motor difficulties. As neuroscience advances a preoccupation with the distinction may hinder the assessment and treatment of individual cases.

Aged↗
PubMedDate not supplied

FDG-PET findings in the Wernicke-Korsakoff syndrome.

This study reports FDG-PET findings in Wernicke-Korsakoff patients. Twelve patients suffering amnesia arising from the Korsakoff syndrome were compared with 10 control subjects without alcohol-related disability. Subjects received [18F]-fluorodeoxyglucose (FDG-PET) imaging as well as neuropsychological assessment and high-resolution MR imaging with volumetric analysis. Volumetric MRI analysis had revealed thalamic and mamillary body atrophy in the patient group as well as frontal lobe atrophy with relative sparing of medial temporal lobe structures. Differences in regional metabolism were identified using complementary region of interest (ROI) and statistical parametric mapping (SPM) approaches employing either absolute methods or a reference region approach to increase statistical power. In general, we found relative hypermetabolism in white matter and hypometabolism in subcortical grey matter in Korsakoff patients. When FDG uptake ratios were examined with occipital lobe metabolism as covariate reference region, Korsakoff patients showed widespread bilateral white matter hypermetabolism on both SPM and ROI analysis. When white matter metabolism was the reference covariate; Korsakoff patients showed relative hypometabolism in the diencephalic grey matter, consistent with their known underlying neuropathology, and medial temporal and retrosplenial hypometabolism, interpreted as secondary metabolic effects within the diencephalic-limbic memory circuits. There was also evidence of a variable degree of more general frontotemporal neocortical hypometabolism on some, but not all, analyses.

Adult↗
PubMedDate not supplied

Retrograde amnesia in patients with hippocampal, medial temporal, temporal lobe, or frontal pathology.

There is considerable controversy concerning the theoretical basis of retrograde amnesia (R.A.). In the present paper, we compare medial temporal, medial plus lateral temporal, and frontal lesion patients on a new autobiographical memory task and measures of the more semantic aspects of memory (famous faces and news events). Only those patients with damage extending beyond the medial temporal cortex into the lateral temporal regions showed severe impairment on free recall remote memory tasks, and this held for both the autobiographical and the more semantic memory tests. However, on t-test analysis, the medial temporal group was impaired in retrieving recent autobiographical memories. Within the medial temporal group, those patients who had combined hippocampal and parahippocampal atrophy (H+) on quantified MRI performed somewhat worse on the semantic tasks than those with atrophy confined to the hippocampi (H-), but scores were very similar on autobiographical episodic recall. Correlational analyses with regional MRI volumes showed that lateral temporal volume was correlated significantly with performance on all three retrograde amnesia tests. The findings are discussed in terms of consolidation, reconsolidation, and multiple trace theory: We suggest that a widely distributed network of regions underlies the retrieval of past memories, and that the extent of lateral temporal damage appears to be critical to the emergence of a severe remote memory impairment.

Adult↗
PubMedDate not supplied

Experience and perspectives on the classification of organic mental disorders.

The official diagnostic classification systems have been increasingly employed in the last few years, and this is true of both ICD-10 and DSM-IV. We will propose a few principles which should be considered when revisions are attempted. Our existing classifications should be simplified, but new syndromes incorporated where they have pathological justification. Links to other specialist diagnostic classifications should be made (e.g. in epilepsy, sleep disorders, dementias) wherever possible. A broader range of 'Neuropsychiatric Disorders' should be incorporated, including alcohol-related organic disorders, head injury, sleep disorders, if possible including the 'psychogenic syndromes'. Progressive, degenerative disorders need to be clearly distinguished from non-progressive syndromes, and some gradation of severity needs to be built into the classificatory system. Finally, the definitions need to be concise and accurate.

Humans↗