WAVELENGTH SENSITIVITY OF RETINAL GANGLION CELLS IN THE CAT.
Final rept. 1 Feb 66-31 Jan 69,
EYE RESEARCH FOUNDATION BETHESDA MD
Pagination or Media Count:
Spike activity elicited by wide field monochromatic stimulation was recorded from single retinal ganglion cells of cats anaesthetized with barbiturate. Stimulus wavelengths between 400 and 700 nm were used, at luminance levels corresponding to human photopic vision. At least two photosensitive mechanisms are functional under these conditions. These mechanisms differ in overall sensitivity and in spectral sensitivity. The evidence for more than one system includes 1 although the majority of the units have a spectral sensitivity based on rhodopsin, some show a sensitivity function that is shifted toward longer wavelengths 2 chromatic adaptation causes selective changes in sensitivity in some units 3 some units show a Purkinje shift as stimulus radiance is varied 4 the temporal pattern of response may change with wavelength and this change cannot be reversed by adjusting radiance. Two means of transmitting color information are therefore possible a spatial code based on differences in the spectral sensitivity of individual optic nerve fibers and a temporal code based on response frequency at given delays after a change in the stimulus or after an eye movement. Author
- Anatomy and Physiology