SPECTRAL COMPONENTS IN THE B-WAVE OF THE GROUND-SQUIRREL ELECTRORETINOGRAM

In the light of the recent discovery that the ground squirrel retina contains a small population of rods in addition to many cones, the b-wave of the electroretinogram (ERG) was examined to determine what spectral components can be discerned in this response. In confirmation of an earlier report, a clear separation of the b-wave into faster (b1), and slower (b2) components was seen in the ERG recorded from the dark-adapted eye. The spectral sensitivity of the b1 component indicates that it receives input from the cone system primarily responsible for photopic spectral sensitivity in this animal, while the spectral sensitivity of the b2 component matches that expected of a rod-driven response. Although these two components thus appear like the b1 and b2 components in other duplex retinae, it was also found that the two behave similarly during moderate light-adaptation and during dark-adaptation. Most surprisingly, the recovery of sensitivity in the dark is rapid for both components, much as would be expected from cone-like mechanisms. © 1979.