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Biomedical subjects

L S Cermak

Publications and source records attributed to L S Cermak.

At least 37 records · Page 2Linked to original sources
PubMed1991

Reduced cerebral grey matter observed in alcoholics using magnetic resonance imaging.

Twenty-eight chronic alcoholics and 36 age- and sex-matched non-alcoholic controls were examined with magnetic resonance imaging and brain morphometric analyses. Results confirmed large increases in subarachnoid cerebrospinal fluid (CSF) volume and mild ventricular enlargement in the alcoholics and revealed associated volume reductions of localized cortical and subcortical cerebral structures. Volume losses in the diencephalon, the caudate nucleus, dorsolateral frontal and parietal cortex, and mesial temporal lobe structures were the most prominent. Significant correlations between increments in cortical and ventricular CSF and decrements in the volume of cortical and subcortical grey matter were noted. Although there was little evidence for relationships between performance on neuropsychological tests and volume of grey matter structures, significant correlations between some cognitive measures and subcortical and cortical fluid volumes were found. The parallels between this pattern of affected structures and recent neuropathological findings are discussed.

Adult↗
PubMed1991

Magnetic resonance imaging of alcoholic Korsakoff patients.

Eight patients with alcoholic Korsakoff's syndrome were compared to age-matched groups of normal controls and nonamnesic chronic alcoholic patients using magnetic resonance imaging (MRI). Quantitative image-analytic techniques were used to estimate volumes of ventricular and cortical cerebrospinal fluid (CSF), as well as cortical and subcortical grey matter structures. For the nonamnesic alcoholics, these volume analyses revealed large CSF increases with some circumscribed decreases in grey-matter volumes. In contrast, alcoholic Korsakoff patients showed widespread reductions in grey matter volumes in addition to CSF increases, with greatest reductions observed in diencephalic structures. The volume losses that best differentiated the Korsakoff patients from the alcoholic controls included losses in anterior portions of the diencephalon, mesial temporal lobe structures, and the orbitofrontal cortices. These findings suggest that damage to structures other than the mesial thalamic nuclei, such as the hypothalamus and hippocampus, may contribute to the Korsakoff patients' amnesic symptoms.

Aged↗
PubMed1990

Strategic and automatic priming of semantic memory in alcoholic Korsakoff patients.

To examine whether the organization of semantic memory is intact in alcoholic Korsakoff patients, three semantic memory tasks which do not require active search for stored information were administered to a group of Korsakoff patients and alcoholic controls. The first two tasks used a perceptual identification paradigm in which patients had to identify briefly presented targets preceded by associatively (experiment 1) or categorically (experiment 2) related primes. On both tasks, Korsakoff patients demonstrated intact priming effects. Because priming in these tasks was thought to reflect the operation of strategic processes, experiment 3 was designed to assess automatic spreading activation using a lexical decision task. Here as well, Korsakoff patients demonstrated intact priming. Taken together, these results support the view that the organization of semantic memory in Korsakoff patients has not been disrupted by their brain injury. The implications of these findings for understanding Korsakoff patients' impaired performance on semantic search tasks are discussed.

Aged↗
PubMed1989

Verbal and nonverbal right hemisphere processing by chronic alcoholics.

The theory that chronic alcoholism produces a right hemisphere deficit has generally been tested using visuospatial tasks. The present report tested the theory using three tasks that tap functions, other than visuospatial abilities, which have been failed by patients with right hemisphere damage. The first task assesses the ability to draw a correct inference by integrating information from two unrelated sentences. The second taps the patient's capacity to appreciate humor. The third requires the patient to interpret the emotion displayed in a face. On all three tasks, the pattern of responses of chronic alcoholics differed from that of patients with right hemisphere damage. Thus, the right hemisphere deficit theory fails to gain support from this investigation. On the other hand, the chronic alcoholics' performance was impaired relative to contemporary controls on the first two tasks, although not on the last. On the first two tasks, alcoholics' impairment approximated, and in one instance exceeded, that seen in normal elderly controls. Thus, a premature aging hypothesis received modest support from this study.

Aged↗
PubMed1988

Deficits in the implicit retention of new associations by alcoholic Korsakoff patients.

Word-stem completion in the presence or absence of a paired associate was assessed for a group of amnesic Korsakoff patients and a group of alcoholic controls. Since neither group demonstrated facilitation in the presence of cues (Experiment 1), an analysis of the influence of instructions to remember the paired associates on cued word-stem completion was performed with college students (Experiment 2). Finding a positive effect of instructions led to a replication of the task with amnesic patients and alcoholic controls. Unfortunately, instructions to remember the pairs did not produce the facilitatory effect for either group nor for an age matched nonalcoholic control group. (Experiment 3). It was concluded that neither amnesics, chronic alcoholics, nor elderly controls had the ability to modify their analysis of verbal material as a function of retrieval expectations. As a consequence, neither group demonstrated the effect of contextual priming of word completions reported by P. Graf and D. L. Schacter (1985, Journal of Experimental Psychology: Learning, Memory and Cognition, 11, 501-518).

Adult↗
PubMed1988

The implicit memory ability of a patient with amnesia due to encephalitis.

The implicit memory ability of a patient (S.S.) with severe amnesia due to encephalitis was assessed using five independent paradigms: Perceptual priming with real words and pseudowords; Word-stem completion with and without contextual cues; Word-stem completion following presentation of high- vs. low-frequency words; Biasing of the spelling of ambiguous (homophonic) words; and Conceptual priming. On the tasks in which previously acquired knowledge could potentially be activated by a prime (e.g., perceptual priming with real words), both S.S. and the Korsakoff patients performed on a normal level. However, when new learning or new associations had to be formed prior to implicit memory testing (e.g., perceptual priming of pseudowords or contextual word-stem completion), S.S.'s implicit memory performance was superior to Korsakoff amnesics. These results suggested that new learning differentially affects the priming abilities of S.S. and alcoholic Korsakoff patients. Since S.S.'s amnesia is as severe as Korsakoff patients, it was also concluded that severity of amnesia is clearly not the sole determinant of priming capacity; etiology may be equally important.

Amnesia↗
PubMed1988

Preserved topographical memory following right temporal lobectomy.

In an attempt to study remote memory for visuospatial information, geographical knowledge was examined in patient J.N., who had received a radical right temporal lobectomy to remove a large glioblastoma. In postoperative tests J.N. displayed severe deficits in anterograde memory for visuospatial and verbal material, visuoperceptual functions, constructions, attention, and response initiation. Despite her global cognitive deficiencies she performed normally on the WAIS Information Scale and the Fargo Map Test, a measure of geographical knowledge. In contrast, patients known to have severe amnesia exhibited impairments on tests of geographical knowledge that required precise localization of features such as cities. Assuming that J.N.'s performance is typical of patients with extensive damage to the right temporal lobe, the findings suggest that the integrity of the right temporal lobe is not essential for the retrieval of premorbidly established visuospatial memories.

Adult↗
PubMed1986

Semantic encoding deficits in frontal lobe disease and amnesia.

The relationship between semantic encoding deficits and memory dysfunction was evaluated for the following groups: amnesic patients with bilateral frontal lobe lesions; nonamnesic patients with bilateral frontal lesions; and alcoholic Korsakoff patients. Semantic encoding was assessed using the Wickens' release from proactive interference (PI) paradigm. Korsakoff patients and the poor memory frontal lobe patients failed to show automatic PI release, while good memory frontal patients did show a release. These results support the view that an encoding disability is a contributor to amnesics' memory disorder and they suggest a possible neuroanatomical correlate for impaired semantic encoding.

Alcohol Amnestic Disorder↗
PubMed1986

Biasing of alcoholic Korsakoff patients' semantic memory.

The extent to which the spelling of ambiguous words could be biased and the length of time this biasing could be maintained were investigated in three studies. Biasing occurred for amnesic Korsakoff patients but the effect was consistently more fragile than the biasing pattern of alcoholic control patients. Between-group differences were due to the differential dependency of amnesics' biasing upon the activation of semantic memory. The spelling bias of the alcoholic control patients appeared to be based on both semantic activation and episodic retention.

Adult↗
PubMed1985

The perceptual priming phenomenon in amnesia.

Alcoholic Korsakoff patients and controls were given three variants of a priming task. In the first task, a study list of words was followed by a recognition test phase and then a perceptual identification test phase. In the second task, the order of the two test phases was reversed. The amnesics performed like normals on the priming for identification task and the delay did not affect their performance. However, recognition by amnesics was significantly impaired when the delay was introduced; although it too was normal with no delay. In a third task, pseudowords were used as stimuli. Under these conditions the amnesics could not be primed nor could they recognize the material. The implications of these findings for current theories of amnesia were discussed.

Alcohol Amnestic Disorder↗
PubMed1985

Memory disorders associated with Huntington's disease: verbal recall, verbal recognition and procedural memory.

Two experiments were conducted to evaluate the hypothesis that the memory disorders of Huntington's Disease (HD) patients are characterized by deficiencies in both retrieval mechanisms and the acquisition of procedural (skill-based) information. In the first study, verbal recall and recognition tests were administered to HD patients, amnesics and normal control (NC) subjects. Although the two patient groups were impaired relative to NC subjects on both recall and recognition of word lists, the performance of the HD patients was superior to that of the amnesics on the recognition test. In the second experiment early HD (EHD), advanced HD (AHD), amnesic and NC subjects were compared in the acquisition of the 'Tower of Hanoi' puzzle. Both the NC subjects and EHD patients acquired the solution of this puzzle after repeated trials, whereas the AHD and amnesic patients evidenced little improvement. However, on a recognition test assessing memory for facts about the puzzle, both the EHD and AHD patients were superior to the amnesic subjects. These results are consistent with the retrieval hypothesis but are equivocal with regard to the HD patients' proposed deficit in skill learning. Since the 'Tower' puzzle may rely heavily on both problem solving and skill learning capabilities, it may be of limited value in searching for double dissociations between patient groups and the acquisition of skill-based and data-based knowledge.

Adult↗
PubMed1984

Reconstructive retrieval deficits in Broca's aphasia.

Anterior aphasic patients' ability to utilize the phonemic and/or semantic features of verbal material for retention purposes was investigated. In the first experiment, patients were asked to either detect word repetitions, phoneme repetitions, or rhymes in a list of items. The aphasics performed well on word and phoneme repetition detection but below both normals and amnesic Korsakoffs on rhyme detection. In the second experiment the patients were instructed to analyze either the physical, phonemic, or semantic features of words they were later asked to recognize. Aphasics were differentially affected (as were normals) by these instructions: semantic feature analysis resulted in the best performance, followed by phonemic feature analysis. It was concluded that anterior aphasics can analyze, recirculate, and even store the phonemic features of words, but find difficulty in reconstructing the originally presented item from these features.

Alcohol Amnestic Disorder↗
PubMed1983

The anterograde and retrograde retrieval ability of a patient with amnesia due to encephalitis.

A patient with amnesia due to encephalitis was previously described in 1976 as having normal short-term memory and an intact ability to perform semantic analysis. Despite this ability, his retention beyond the limits of short-term memory was nearly nil. The present investigation sought to evaluate more completely the nature of this patient's retrieval deficit using a series of paradigms developed subsequent to his initial testing. Once again it was discovered that while his intact analytic abilities allowed retention of material in working memory, as soon as that working capacity was exceeded, retrieval of information became nearly impossible. It became apparent that the patient could not discriminate between a cue's most recently analyzed associate and the strongest existing associate to that cue in his semantic hierarchy. An analysis of his retrograde memory ability showed that he could retrieve almost no real episodes of either a public or private nature from his past. Instead, he seemed to rely on generalizations from his semantic memory to reconstruct "probable" events.

Amnesia↗
PubMed1982

Recall failure following successful generation and recognition of responses by alcoholic Korsakoff patients.

Amnesic Korsakoff patients and controls were presented with twelve words, each shown individually in the presence of a weak associate. They were then asked to freely associate to 12 other words that were strong associates of the to-be-remembered (TBR) words. The Korsakoff patients generated, and were able to recognize, as many of the TBR words as the controls. Yet, in spite of this recognition ability, these same patients were subsequently unable to recall the critical TBR words when the weak cues were again presented. A follow-up study found that the same recognition results could be obtained with Korsakoffs months after initial presentation suggesting that the patients might initially have "recognized" the most highly associated words simply because they represented the most probable choices. Intermediate association prompts failed to generate correct responses. It was hypothesized that the Korsakoff patients cannot restructure their semantic associative hierarchy during input in such a way as to become sensitized to other than the strongest associates as prompts during recall.

Alcohol Amnestic Disorder↗
PubMed1982

Continuum versus premature aging theories of chronic alcoholism.

An attempt is made to differentiate, both theoretically and experimentally, the continuum theory from the premature aging theory of the chronic effects of alcohol on verbal information processing. It is argued that the continuum model necessitates a demonstration of differential 'pattern' of performance between alcoholics and normals in as much as alcoholic Korsakoff patients (at one end of the continuum) do demonstrate such patterns. Premature aging theories, on the other hand, need to demonstrate only subnormal performance by alcoholics relative to their contemporaries. Two experiments designed to assess these theories provided some evidence for premature aging but none for the continuum theory.

Adult↗