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Colour, contrast and the visual evoked potential
Author(s) -
Thompson Dorothy A.,
Drasdo Neville
Publication year - 1992
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.1992.tb00295.x
Subject(s) - parvocellular cell , chromatic scale , contrast (vision) , luminance , spatial frequency , evoked potential , optics , neuroscience , physics , biology , central nervous system
Visual evoked potentials exhibit interesting morphological changes when they are elicited by checkerboards of different spatial and chromatic contrast, counterphasing in the Coveal and lower macula Held. The characteristic, positive wave of the phase‐reversal visual evoked potential, for example, is preceded by an increasingly prominent negative peak as luminance contrast progressively increases above 10% and, at isoluminance, the response to red and green checkerboards becomes a predominantly monophasic negative wave. To study the nature of the morphological change we synthesized these waveforms with a computer simulation consisting of Gaussian components. The amplitudes of positive and negative components were altered until the synthesized response was closely similar to the recorded data. These Gaussian components have response characteristics which are identified with those of magnocellular and parvocellular neurones.