Light-dependent synaptic delay between photoreceptors and horizontal cells in the tiger salamander retina.

A long delay between the time to peak of the photoreceptor and horizontal cell light responses was observed in dark-adapted tiger salamander retinas. The rise of the HC light responses follows a biphasic time-course which is probably mediated by the removal of the rod and cone transmitters, but not by voltage-dependent mechanisms in the HC membrane. A bleaching white light shortens the signal delay and results in a faster and monophasic rise of the HC light responses mediated predominantly by the cones.