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Biomedical subjects

S Handel

Publications and source records attributed to S Handel.

17 recordsLinked to original sources
PubMed1992

The differentiation of rhythmic structure.

Listeners judged whether two five-tone nonmetric rhythms were the same or different. Each rhythm was presented one, two, or four times to study the process of perceptual differentiation. The results indicated that the listeners perceived these rhythms in terms of the grouping of the tones, and not in terms of the timing between the groups. Two rhythms that had the same perceptual grouping were judged as being identical, even if the timing between the groups was different. The perception of the groupings of tones developed gradually. If each rhythm was presented only once, then the listeners had only a global percept, focused on groups (runs) of three elements, and often judged two different rhythms as being identical. If the rhythms were presented two or four times, then the grouping of the tones became more differentiated and the listeners were less likely to judge different patterns as being identical. Thus, perception of auditory rhythmic structure appears to follow the same developmental process as the perception of visual spatial structure.

Adult↗
PubMed1991

The effect of amphetamine on regional cerebral blood flow during cognitive activation in schizophrenia.

To explore the role of monoamines on cerebral function during specific prefrontal cognitive activation, we conducted a double-blind placebo-controlled crossover study of the effects of 0.25 mg/kg oral dextroamphetamine on regional cerebral blood flow (rCBF) as determined by 133Xe dynamic single-photon emission-computed tomography (SPECT) during performance of the Wisconsin Card Sorting Test (WCST) and a sensorimotor control task. Ten patients with chronic schizophrenia who had been stabilized for at least 6 weeks on 0.4 mg/kg haloperidol participated. Amphetamine produced a modest, nonsignificant, task-independent, global reduction in rCBF. However, the effect of amphetamine on task-dependent activation of rCBF (i.e., WCST minus control task) was striking. Whereas on placebo no significant activation of rCBF was seen during the WCST compared with the control task, on amphetamine significant activation of the left dorsolateral prefrontal cortex (DLPFC) occurred (p = 0.0006). Both the mean number of correct responses and the mean conceptual level increased (p less than 0.05) with amphetamine relative to placebo. In addition, with amphetamine, but not with placebo, a significant correlation (p = -0.71; p less than 0.05) emerged between activation of DLPFC rCBF and performance of the WCST task. These findings are consistent with animal models in which mesocortical catecholaminergic activity modulates and enhances the signal-to-noise ratio of evoked cortical activity.

Adult↗
PubMed1988

Space is to time as vision is to audition: seductive but misleading.

Space and time serve two perceptual functions. First, space/time forms a framework for visual and auditory events. Second, spatial and temporal change defines the properties of events and objects. It is at this second level that correspondences (i.e., mappings) between visual and auditory qualities can be hypothesized. Due to the active nature of perceiving, all such mappings illustrate the possible relations between looking and listening.

Attention↗
PubMed1987

Neurobehavioral functioning and magnetic resonance imaging findings in young boxers.

In a prospective investigation of neurobehavioral functioning in young boxers, 13 pugilists and 13 matched control subjects underwent tests of attention, information-processing rate, memory, and visuomotor coordination and speed. The results disclosed more proficient verbal learning in the control subjects, whereas delayed recall and other measurements of memory did not differ between the two groups. Reaction time was faster in the boxers than in the control subjects, but no other differences were significant. Ten subjects in each group were retested 6 months later and exhibited improvement in their neuropsychological performance as compared to baseline measurements. However, there were no differences in scores between the boxers and the control subjects at the follow-up examination or in the magnitude of improvement from baseline values. Magnetic resonance imaging, which was performed in nine of the boxers, disclosed normal findings.

Adult↗
PubMed1979

The sella turcica in primary end organ failure.

Pituitary hyperplasia, or adenoma, may result from end or target organ failure as seen in primary hypothyroidism and hypogonadism. Associated enlargement of the sella turcica and contour alterations without significant increase in volume may be seen. A review was made of 12 patients with end organ failure demonstrating the spectrum of radiologic changes within the sella turcica. Recognition of pituitary enlargement resulting from end organ failure may eliminate unnecessary surgery.

Adenoma↗
PubMed1977

Changing venous pattern in a hemangioblastoma resembling an arteriovenous malformation.

A patient with cerebellar hemangioblastoma underwent two successive cerebral arteriograms within a 48-hour period. The first arteriogram suggested an arteriovenous malformation. The second angiogram showed a dramatic change with nearly total absence of the earlier dilated draining veins. This change was found on examination of the surgical specimen to be caused by venous thrombosis.

Adult↗
PubMed1976

The role of pattern goodness in the reproduction of backward masked patterns.

Four experiments investigated the role of pattern goodness in backward masking using five- and four-dot patterns constructed by placing dots in the cells of a 3 x 3 matrix. In Experiment 1, subjects rated the goodness of these patterns and the results replicated previous work showing that good patterns had few alternatives. In Experiment 2, the dot patterns were the target stimuli in a backward masking task using a variety of masking stimuli. For all masking, good patterns were reproduced more accurately than poor patterns. In Experiment 3, the goodness of the masking stimulus was varied. The results indicated that good patterns were reproduced more accurately (replicating Experiment 2) and that good patterns were less effective as stimulus than were poor patterns. In Experiment 4, a long interstimulus interval which precluded masking was used to determine whether goodness affected encoding or memory. At these intervals, there were no differences among patterns, suggesting that the effect of pattern goodness was on rate of encoding. These results demonstrate the importance of configural properties in pattern perception.

Discrimination, Psychological↗
PubMedDate not supplied

MR imaging of optic pathways in patients with neurofibromatosis.

Twenty-one patients with documented neurofibromatosis had MR examinations to evaluate possible intracranial disease. In five cases the indication was a known or suspected optic glioma. Two patients were examined because of a history of seizures; the rest were examined as part of a baseline evaluation. Eighteen patients showed evidence of signal hyperintensity on T2-weighted images. Lesions involved the optic nerves, optic chiasm, optic tracts, lateral geniculate body, optic radiations, basal ganglia, periventricular white matter, cerebellar white matter, and dentate nucleus of the cerebellum. Comparison between MR and concurrent CT scans showed MR to be superior in demonstrating the posterior extent of optic-pathway gliomas. In addition, MR showed focal areas of hyperintensity in the basal ganglia, internal capsule, cerebellum, and/or white matter that were not detected on CT. Although we found MR to be superior to CT in detecting intracranial tumors in patients with neurofibromatosis, and in evaluating the extensive involvement of known lesions, the full clinical implications of our findings remain to be determined.

Adolescent↗