Biomedical subjects
Publications and source records attributed to A Benton.
The achievements of Henry Hécaen, Oliver Zangwill, Hans-Lukas Teuber, and Norman Geschwind are reviewed. Each made an enormously significant contribution to the form and content of the field of neuropsychology as we know it today.
The performances of patients with stroke-produced unilateral hemispheric lesions on a test requiring the identification of lines were examined in the light of a recent report that contradicted previous observations. The study confirmed the results of earlier studies that patients with lesions of the right hemisphere show a remarkably high frequency of defective performances while those with lesions of the left hemisphere do not. Possible reasons for findings that deviate from this rule are discussed.
Clinical neuropsychology has made significant progress during the past 30 years. Practice and research have expanded remarkably in scope and are more incisive and more highly focused. There has been an explosive development of test methods but clinical neuropsychologists have yet to take full advantage of them. An effort should be made to combine the strengths of the "fixed battery" and "flexible" approaches to assessment. Further advances in neuropsychological assessment will come about only to the degree that they are linked to evolving concepts of brain-behavior relationships. Neuropsychologists now require a deeper understanding of basic neuroscience and cognitive psychology than was true in the past. Steps should be taken to insure that training to achieve that understanding is provided to the upcoming generation of neuropsychologists.
The research of Henry Hécaen and Oliver Zangwill on patients with unilateral brain lesions in the later 1940s and early 1950s ushered in the modern era of investigation of hemispheric cerebral dominance. The field of inquiry expanded far beyond language and visual perception to encompass audition, somesthesis, motor performance, attentional processes, emotionality, and psychiatric disorders. The hundreds of studies dealing with the topic indicate that hemispheric dominance is not an all-or-none phenomenon and that, to some degree, it is an unstable phenomenon dependent upon bihemispheric factors. The basic cognitive processes that are preferentially mediated by each hemisphere and the factors that produce changes in performance still require adequate definition.
A review of recent studies of prosopagnosia suggests that the weight of evidence has shifted in favor of regarding it as a disability that can be produced by a right hemisphere lesion alone even though bilateral disease remains the more frequent anatomical basis. It is possible that prosopagnosia resulting from a right hemisphere lesion occurs only within the context of some atypical condition of the left hemisphere. "Types" of prosopagnosia continue to be postulated and the "identification of individuality" hypothesis continues to be advanced. Autonomic and covert recognition studies of prosopagnosic patients have described a new dimension in facial identification. Right hemisphere dominance for the discrimination of unfamiliar faces in non-aphasic patients has been confirmed but the performances of left-hemisphere damaged aphasic patients has still not been fully investigated. New developments include the study of developmental prosopagnosia and novel applications of test of facial discrimination.
Two factors associated with measurements of RT, viz., the role of task complexity and the relationship of RT to locus and size of lesion, are considered. Analysis of the literature suggests that the two factors are interrelated. There appears to be a trend for the complexity gradient to be steeper in patients with widespread brain damage than in those with focal lesions. Although simple RT is generally reported to be slower in patients with right hemisphere lesions, there are indications that complex RT may be slower in patients with left hemisphere lesions. The multiplicity of procedures utilized in different studies is probably responsible for some of the inconsistent findings in the literature. Explicit definition of these procedures and the employment of combinations of them should resolve these inconsistent findings and help to elucidate the relationship between RT and cerebral status.
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Analysis of early medical literature indicates that considerable evidence for a specific association between speech disorder and disease of the left hemisphere was incorporated within it. The diverse reasons for the failure of clinicians to perceive the association are discussed and the approach of Marc Dax to the question is described.
Reaction time (RT) of normal subjects to square-wave gratings of two different frequencies were related to locus of presentation, area, and stimulus complexity. Each frequency was presented to either side of the horizontal meridian (half size stimulus) or both sides stimultaneously (full size stimulus). The two different frequencies were also flashed simultaneously to both hemifields (compound stimulus). Stimulus position affected RT with the 1 c/deg stimulus, RT being faster for the lower hemifield. With presentation on both sides of the horizontal median simultaneously or of the two spatial frequencies, the resulting RT was equal to that of the faster component. Implications of the results for the functional organization of the visual system are discussed.
Sustained releases of the microhymenopteran pupal parasite Spalangia endius, at a commercial poultry installation in north Florida, completely suppressed a population of houseflies with in 35 days.
The accuracy of identifying the slope of briefly exposed lines was assessed in patients with lesions of the left or right hemisphere and in a group of control patients without history or evidence of brain disease. The frequency of impaired performance was remarkably high in the patients with right hemisphere lesions. In contrast, the patients with left hemisphere lesions did not perform differently from the control group. Visual field defect, aphasic disorder, and age were not related to performance level. The striking interhemispheric difference in performance on this visuospatial task suggests its further development for clinicodiagnostic purposes.
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Explore the source record for details and available documents.