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Biomedical subjects

S Bentin

Publications and source records attributed to S Bentin.

At least 55 records · Page 3Linked to original sources
PubMed1984

Intermanual information transfer in patients with lesions in the trunk of the corpus callosum.

Interhemispheric transfer of haptic information was examined in six partially callosotomized patients and three control subjects. Three different portions of the trunk were severed in different subjects. The most anterior 10 mm of the trunk, anterior to the foramen of Monro, was sectioned in one patient. Three other patients had lesions restricted to the anterior part of the trunk posterior to the foramen of Monro. The posterior third of the trunk was damaged in two patients. The splenium, genu and rostrum of the corpus callosum were intact in all six patients, as were the anterior and hippocampal commissures. Poor transfer of haptic information was found only in the three patients with the lesion located in the anterior part of the trunk posterior to the foramen of Monro. The functional anatomy of this region is discussed. It is assumed to house fibers responsible for interhemispheric transfer of complex tactile information.

Adolescent↗
PubMed1984

Orthographic and phonemic coding for lexical access: evidence from Hebrew.

In Hebrew script, vowels are represented by small dots appended to the consonants. However, in print the dots are almost always omitted, and because a single consonant string may represent several different words (with different vowels), the reader can assign to it a unique meaning and pronunciation only in relation to the syntactic and semantic contexts. We investigated the role of phonemic mediation for lexical access when printed Hebrew words are presented in isolation. Two experiments manipulated phonemic ambiguity by comparing consonant strings that have only a single meaningful pronunciation with strings that have several meaningful pronunciations. Although naming was slower when several pronunciations were possible, these phonemically ambiguous strings were not recognized more slowly in a lexical-decision task. A third study, in which lexical decisions were made for consonant strings presented with the vowel dots, showed that nonword homographs were rejected more slowly than were nonword homophones. These results suggest that in Hebrew, orthographic codes play a more important role in the process of word recognition than do phonemic codes, especially in comparison with the roles played in other languages.

Female↗
PubMed1981

Asymmetrical cognitive deterioration in demented and Parkinson patients.

Patients with Parkinson's disease and patients with dementia showed greater deterioration on functions attributed to the right cerebral hemisphere, than on functions attributed to the left. Relative to matched controls, Parkinson patients were significantly impaired on right hemisphere tests, but did not differ on left hemisphere tests. Demented patients were significantly deficient on all tests, but right decline was greater than left. Ninety-six patients were tested: 32 diagnosed as senile or presenile dementia, 32 Parkinson patients, and 32 non-neurological patients matched for age, sex and education. Functional performance was assessed by a battery of validated tests for left and right hemisphere cognitive functions. Patients were defined with two scores based on the results of the test: Cognitive Laterally Quotient (CLQ) reflecting the averaged performance on the left hemisphere tests, subtracted from the average performance on right hemisphere tests, and Cognitive Performance Quotient (CPQ), reflecting the total level of performance of both hemispheres. These measures defined a characteristic cognitive profile for each group.

Aged↗
PubMed1981

Selective language deterioration in chronic schizophrenia.

Chronic schizophrenics as a group were inferior to controls on tests of neuropsychological function. When divided into groups according to length of illness they differed from each other primarily in tests of language. No other deficits in cognitive function progressed; the performance of the patients on memory, visuo-spatial tasks, rate of information processing and abstract thinking did not decline according to length of illness. The results indicate that chronic schizophrenia is characterised by a selective deterioration of language, which correlates with the notion that schizophrenia may be associated with left hemisphere dysfunction.

Adult↗
PubMed1979

Regional cerebral blood flow in patients with Parkinson's disease.

Regional cerebral blood flow (rCBF) was measured by the xenon 133 inhalation method in 60 patients with Parkinson's disease and compared with flow data obtained in 51 age-matched normal control subjects. Mean brain rCBF was significantly reduced in patients with parkinsonism (9.5%, P less than .001). The most marked and significant rCBF decreases were observed in the older patients (18.8%, P less than .001). There was no correlation between degree of rCBF reduction and duration of parkinsonism. Decreases in hemispheric mean rCBF values were similar in both hemispheres even in patients with unilateral signs. The present study provides additional evidence for involvement of the cerebral cortex in Parkinson's disease. The rCBF decline may be associated in part with high prevalence of mental impairment and cortical atrophy and with diminished cerebral metabolic rate due to brain dopamine deficiency in patients with parkinsonism.

Adult↗
PubMed1979

Pseudostereoscopic illusion caused by interhemispheric temporal disparity: clinical and experimental observations.

An extension of Pulfrich's pseudostereoscopic illusion to a situation without interocular disparity, ie, even under purely monocular circumstances, was clinically observed and experimentally produced. The perceived distortion of the movement of a swinging pendulum was found to depend on different combinations of interhemispheric disparity induced by selective prolongation of the conduction time from the nasal or temporal retina to the corresponding hemisphere. In patients, tumor pressure caused the slower conduction time. In normal subjects, neutral density filters covering different visual fields produced similar conduction delays under experimental conditions. Recording the visually evoked response from over each hemisphere provided an objective tool for demonstration and measurement of interhemispheric differences of retinocortical conduction times in various clinical and experimental setups.

Adult↗
PubMed1979

Assessment of cognitive asymmetries in brain-damaged and normal subjects: validation of a test battery.

A test battery designed to assess cognitive functions normally related to the left and right cerebral hemispheres was validated on 30 patients with unilateral (16 right, 14 left) lesions. The tests were preselected to reflect typical functioning of the hemispheres according to general agreement in the literature. A Cognitive Laterality Quotient (CLQ) was calculated from the difference in performance between the "right" and "left" test batteries and, therefore, reflected the relative functioning attributed to the right and left hemispheres. Using the CLQ measurement and a control group of 30 non-neurological patients matched for age and education, 28 out of 30 brain-damaged patients (93%) were categorised correctly according to side of lesion; the other two were considered to have either abnormal lateralisation (one was left handed) or asymmetrical premorbid cognitive profiles. Using only one (paired) test whose two subparts were designed to vary only slightly in task requirements to measure either right or left functioning, 29 out of 30 patients were correctly categorised. It is suggested that the concept of relative assessment of basic cognitive functions is more fruitful than general assessment of intellectual functions for use in diagnosis and rehabilitation of neurological patients or normal subjects with developmental or acquired behavioural cognitive abnormalities.

Adult↗
PubMed1978

Bihemispheric decreases of regional cerebral blood flow in dementia: correlation with age-matched normal controls.

Regional cerebral blood flow (rCBF) was measured by the xenon 133 inhalation method in 20 patients with senile and presenile dementia, and values were compared with flow data obtained in a series of 44 age-matched normal controls. The rCBF was reduced in patients with both presenile and senile dementia, and the degree of decrease exceeded the age-related rCBF decline in normal subjects. Similar rCBF reductions were observed in the left and right cerebral hemispheres and in general were homogeneously distributed in the various areas. The rCBF reductions in normal aging and in dementia may be associated with similar underlying cerebral morphological changes. Our findings suggest that the greater rCBF decreases in dementia compared with the values in age-matched controls may quantitatively reflect more severe pathological alterations in the brains of patients with intellectual deterioration.

Adult↗
PubMed1978

Regional cerebral blood flow in parkinsonism. Measurement before and after levodopa.

Data from recent studies in experimental animals suggest that central dopaminergic mechanisms may be involved in regulation of the regional cerebral blood flow (rCBF) in the mammalian brain. In order to evaluate possible effects of dopaminergic stimulation on human cerebral circulation, rCBF was measured by the 133Xenon inhalation technique in 26 patients with Parkinson's disease before and after the chronic oral administration of levodopa combined with a peripheral Dopa-decarboxylase inhibitor. Treatment with levodopa did not induce significant alterations in the mean brain, mean hemispheric or regional flow values in these patients. These findings suggest that the dopaminergic system does not play an important role in modulation of the rCBF in man.

Adult↗
PubMed1978

Decision-making behaviour during inhalation of subanaesthetic concentrations of enflurane.

The effect of subanaesthetic concentrations of enflurane on decision-making behaviour in risk situations was assessed using a signal detection task. The subject heard noise alone (white noise) or a signal superimposed on the noise (1000-Hz tone) and had to report what he heard in each trial. Risk situations were manipulated by changing the monetary reward and penalty associated with correct and incorrect responses. Eight male volunteers participated in this study. It was found that under anaesthetic influence they did not avoid the same risks which had been avoided under control conditions. The findings are explained in terms of influence of the gas on loss of control and lessened responsibility for the result of behaviour.

Adult↗
PubMed1978

Effects of low concentrations of enflurane on probability learning.

The effects of controlled subanaesthetic concentrations of enflurane on learning behaviour and on ability to change previously developed decision strategies were studied in 10 male volunteers, using a probability learning task. Subjects were instructed to predict on each of 200 consecutive trials, whether a left or a right light would appear. The appearance of lights was pre-determined by a set relative frequency unknown to the subject. The relative frequency was automatically changed at the end of the first 100 trials, from 8/10 lights in the left side to 4/10. It was found that enflurane at subanaesthetic concentration of 0.25% (end-tidal) slowed the rate of learning, and increased the number of trials required for readjusting the prediction strategy to the changed situation.

Adult↗