Electroretinographic b-wave merely reflects the activity of the rod system in the dark-adapted carp retina.
The electroretinogram and responses of intermediate horizontal cells (IHCs) were recorded simultaneously and studied under dark-adapted conditions in intact crucian carp, with the hope of providing an answer to the controversy whether the scotopic b-wave contains contribution from both rods and cones. Our observations indicate that the dark-adapted b-wave follows the univariance principle perfectly in that: (1) b-wave forms and shapes of response amplitude vs light intensity relationships did not depend on the stimulus wavelength; (2) response amplitudes to flashes of mixed wavelengths agreed exactly with the values predicted in accordance with the univariance principle. Furthermore, the spectral sensitivity of the b-wave matched well that of the IHC, receiving input exclusively from rods. In consequence, we conclude that the dark-adapted b-wave merely reflects the activity of the rod system, and the discrepancy between the spectral sensitivities of the b-wave and IHC response compared with the absorption spectrum of the rod photopigment may be due to the self-screening effect caused by the high optical density of porphyropsin in situ.
Yang
X L
XL
Shanghai Institute of Physiology, Academia Sinica, China.
Fan
T X
TX
Li
J D
JD
D000818:Animals; D002347:Carps / Q000502:physiology*; D003530:Cyprinidae / Q000502:physiology*; D003623:Dark Adaptation / Q000502:physiology*; D004596:Electroretinography; D008027:Light; D010786:Photoreceptor Cells / Q000502:physiology*; D012160:Retina / Q000166:cytology; D013053:Spectrophotometry