title: The multifocal visual evoked potential and cone-isolating stimuli: implications for L- to M-cone ratios and normalization.
abstract: Multifocal visual evoked potentials (mfVEP) were recorded with a pattern-reversing display that modulated only the long wavelength-sensitive (L) cones or only the middle wavelength-sensitive (M) cones. Outside the central 5.8 degrees (radius), the ratio of the amplitudes of the mfVEP responses to L- and M-cone modulation varied across the six subjects, ranging from 1.1 to 1.7. The responses from the central 1 degrees (radius) showed a substantially lower ratio, ranging from 0.8 to 1.1 (average of 0.9). The variation among individuals outside the central fovea is probably due to differences in the ratio of the L/M cone input to both magno- and parvocellular pathways. The substantially lower ratios for the central responses is consistent with an L/M cone ratio closer to 1.0 in the central 1 degrees and/or an adjustment in the gain of the L- versus M-cone contributions to the central parvocellular pathways. Taking into consideration evidence from other techniques, we believe it is unlikely that most individuals have a L/M cone ratio of 1.0 in the fovea. Instead, it appears that there is a change in gain before the mfVEP is generated in area 17.
authors.affiliation: Department of Psychology, Columbia University, New York, NY, USA. dch3@columbia.edu
authors.forename: Donald C
authors.initials: DC
authors.lastname: Hood
authors.forename: Alice L
authors.initials: AL
authors.lastname: Yu
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
authors.forename: Johannes
authors.initials: J
authors.lastname: Albrecht
authors.forename: Herbert
authors.initials: H
authors.lastname: Jägle
authors.forename: Lindsay T
authors.initials: LT
authors.lastname: Sharpe
mesh_terms: D000293:Adolescent; D000328:Adult; D003118:Color Perception / Q000502:physiology*; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*