Biomedical subjects
Publications and source records attributed to A McCarter.
Medical labyrinthectomy by systemic administration of streptomycin has proven safe and effective for treatment of selected patients with intractable vertigo. In most patients, 40 grams or less of streptomycin sulfate are required. However, otolaryngologists should be aware that much higher doses can be used safely in selected patients; and a small number of patients may be resistant to streptomycin toxicity even in doses over 100 grams.
The chromatic Hermann grid illusion was investigated in sixteen subjects, with variation of the lightness contrast between the chromatic inducing squares and the background, and the saturation and hue of the inducing squares. Subjects made magnitude estimates of the sharpness and clarity of perceived dots at the intersections of the grid, and matched the appearances of the dots with Munsell chips. A chromatic induction effect was found to occur in the absence of lightness contrast, but the sharpness of the illusory dots increased with increasing lightness contrast (p less than 0.001). The saturation of the perceived dots increased with increases in the saturation of the inducing squares (p less than 0.05), and was higher for the longer wavelengths than for the shorter wavelengths (p less than 0.005). Neural units with center-surround arrangements responding differentially to light of the same color in the center and the surround, e.g. red off-centers and red on-surrounds, could account for the chromatic induction effect.
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The illusion of simultaneous brightness contrast was used to investigate age changes in contrast sensitivity under suprathreshold conditions. Contrary to findings for threshold measures of visual functioning in older adults, the 20 older adults (aged 60-79 yrs.) showed a significantly larger simultaneous brightness contrast effect (p less than .05) than the 20 younger adults (aged 17-26 yrs.). The increase in simultaneous brightness contrast in older adults is attributed to a degeneration of damping fibers in the visual system.
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Explore the source record for details and available documents.