Contrast gain control in the cat visual cortex.
Clicking either of the following will start a download of the document. Please note the file size. Abstract The eye functions effectively over an enormous range of ambient illumination, because retinal sensitivity can be adapted to prevailing light levels. Higher order neurones in the visual pathway are presumably more concerned with relative changes in illumination, that is, contrast, because a great deal of information concerning absolute light level is processed at the retinal level. It would therefore be of considerable functional value if cells in the visual cortex could adapt their response levels to a steady-state ambient contrast, in a manner analogous to the sensitivity control mechanism of the retina.