Scotopic versus photopic pattern onset-offset electroretinograms.
We investigated the contribution of rods and cones to the human pattern electroretinogram to onset and offset checkerboards of different spatial frequency and wavelength in a 39 degrees x 39 degrees field. Under strictly scotopic conditions, there was a negative potential at onset and a positive potential at offset, whereas under photopic conditions, there was a positive potential at onset and a negative/positive potential at offset. Thus, the waveform to pattern onset (offset) was that of the luminance electroretinogram to decreasing (increasing) luminances. For pattern onset, the sensitivity difference 486-601 nm under scotopic and photopic conditions closely followed the luminosity function of rods and cones. The amplitude of the scotopic onset response increased with check size up to 3 degrees 30' and that of the photopic onset response, up to 30'. With larger checks, the scotopic and photopic onset response markedly decreased. This indicates antagonistic center-surround organization of the receptive fields under both scotopic and photopic conditions. By contrast, the offset response monotonically increased with check size under scotopic and photopic conditions, which suggests a luminance component in the pattern electroretinogram. Consequently, the pattern electroretinogram to reversing checkerboards has to be regarded as a mixture of both pattern- (contrast) and luminance-specific components.
Pallas
S
S
Max-Planck-Institute for Physiological and Clinical Research, W. G. Kerckhoff-Institute, Bad Nauheim, Germany.
Schmidt
W
W
Dodt
E
E
D000293:Adolescent; D000328:Adult; D003623:Dark Adaptation; D004596:Electroretinography; D006801:Humans; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology*