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Visual Evoked Responses as a Function of Light Intensity in Down's Syndrome and Nonretarded Subjects
Author(s) -
Gliddon J. B.,
Busk Jytte,
Galbraith Gary C.
Publication year - 1975
Publication title -
psychophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.661
H-Index - 156
eISSN - 1469-8986
pISSN - 0048-5772
DOI - 10.1111/j.1469-8986.1975.tb00015.x
Subject(s) - psychology , audiology , stimulus (psychology) , stimulation , visual evoked potentials , intensity (physics) , evoked potential , neuroscience , medicine , optics , cognitive psychology , physics
Occipital and central averaged visual evoked responses (VERs) were recorded from nonretarded and Down's syndrome (DS) subjects. Three different light intensities were used, all below levels of stimulation used in previous studies. Overall results showed that DS subjects had significantly larger VER perimeters and longer VER latencies, while nonretarded subjects had significant VER asymmetry in the occipital recording (left> right) at all three intensities, DS subjects showed a significantly greater increase in perimeter scores as a function of intensity, with the widest group separation occurring at the highest level of stimulation (43 phots). However, when VER latencies were measured, the widest group separation occurred at the lowest level of stimulation (0.43) phots. Moreover, the only evidence reported thus far for evoked response asymmetry in DS subjects occurred at the lowest light level, These results illustrate the importance of stimulus parameters in evoked potential studies of mental retardation.