Electroretinographic responses that may reflect activity of parvo- and magnocellular post-receptoral visual pathways.
The electroretinogram (ERG) is a complex retinal response to visual stimuli that contains receptoral and post-receptoral components. Here, data are presented using stimuli that isolate the responses of L (long wavelength sensitive)- or M (middle wavelength sensitive)-cones or that stimulate the two simultaneously. The data show that at a temporal frequency of 12 Hz, ERG responses are L- to M-cone opponent with little inter-individual variability. Furthermore, the ratio of L- to M-cone-driven response strengths in the ERGs is about unity. These are also properties of the L- and M-cone opponent chromatic channel mediated by parvocellular activity. Similar to the parvocellular-mediated temporal sensitivity, the ERG response is robust to moderate changes in state of cone adaptation. Thus, the 12-Hz ERG shares distinct characteristics with the post-receptoral red-green sensitive parvocellular pathway. At higher temporal frequencies, the responses are not cone opponent, the inter-individual variability is larger, the mean L/M ratio is larger than unity, and the responses change more strongly when the state of cone adaptation is altered. These properties are reminiscent of the magnocellular non-opponent channel. The data suggest that under well-controlled conditions, the ERG can be used to study post-receptoral processes of the visual system.
Kremers
Jan
J
Department of Ophthalmology, University Hospital Erlangen, Erlangen, Gemany. jan.kremers@uk-erlangen.de
Link
Barbara
B
D000222:Adaptation, Physiological; D000328:Adult; D015350:Contrast Sensitivity; D004596:Electroretinography; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000378:metabolism; D014795:Visual Pathways / Q000378:metabolism*