M- and L-cones in early infancy: II. Action spectra at 8 weeks of age.
Field sensitivities were measured under conditions of M- and L-cone isolation for seven infants (8-12 weeks-old) and two adults, using silent-substitution and the visually evoked potential (VEP). The efficacy of the receptor-isolation conditions were first verified by measuring psychophysical and VEP-derived action spectra from two color-normal adults under conditions of M- and L-cone isolation. M- and L-cone action spectra obtained from the two methods were found to be similar to the Smith and Pokorny M- and L-cone fundamentals, respectively. The VEP-derived action spectra obtained from infants and adults were well fit by the Smith and Pokorny M- and L-cone fundamentals. These data, in conjunction with our previous study, confirm that M- and L-cones are operating by 8 weeks and possibly as early as 4 weeks of age.
Bieber
M L
ML
Department of Psychology, University of Colorado, Boulder 80309-0345, USA. mbieber@psych.colorado.edu
Knoblauch
K
K
Werner
J S
JS
D000328:Adult; D002657:Child Development; D003118:Color Perception / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D011601:Psychophysics; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D013053:Spectrophotometry