ERG recordings of a primate pure cone retina (Tupaia glis)

Abstract

Abstract The gross configuration of the pure coneTupaia ERG is characterized by well-defineda-,x-,c- andd-waves. The short latency, fast risingx-wave contrasts to the slowerb-wave found in all duplex and rod retinas heretofore tested. Thec-wave, not previously reported for pure cone retinas, can usually be avoked during dark adaptation. The off-effect ord-wave appears predictably when stimulus durations are long enough. Several features are consistent with the exclusive presence of cones and their function, including: (1) high FFF, (2) lack of Purkinje shift, (3) high absolute threshold in the dark and only a small increase in the threshold as a function of light adaptation, (4) restricted range of intensity over which amplitude variations are elicited, (5) peak of spectral sensitivity at 552 nm. The spectral sensitivity curve, in contrast to all the other pure cone mammals, shows congruence with the foveal psychophysical curve of the human and with the absorption curve of iodopsin, with the exception of more marked sensitivity in the blue region.