Malchow R P, Yazulla S
Department of Neurobiology and Behavior, State University of New York at Stony Brook 11794.
Brain Res. 1988 Mar 8;443(1-2):222-30. doi: 10.1016/0006-8993(88)91616-2.
Intracellular recordings from rod horizontal cells and luminosity external horizontal cells of the goldfish retina were obtained, and the process of light adaptation induced by steady, full-field background illumination was investigated. Rod horizontal cells had remarkably steep response vs intensity (rvi) functions when dark-adapted. Background illumination reduced the sensitivity of these cells primarily due to response compression, with intense backgrounds resulting in eventual response saturation. Increment threshold functions for these cells were non-linear, and increment saturation was evident when 500-nm backgrounds exceeded 10.5 log photons s-1 cm-2. Cone luminosity cells displayed broad response operating functions when dark-adapted. Light adaptation resulted in substantial narrowing of the rvi function, as well as a shift in the operating function to greater intensities. Response compression played only a minor role in the loss of sensitivity of these cells.
