Identification of new biphasic C-type horizontal cells in cyprinid fish.

New biphasic C-type horizontal cells were identified physiologically and morphologically in the retina of live immobilized crucian carp. These cells, like commonly studied R/G type cells, hyperpolarized to short wavelength lights and depolarized to long wavelength lights, but inverted response polarity at about 560 nm. Spectral sensitivities of hyperpolarizing and depolarizing components showed that they were produced by inputs from blue-sensitive cones and green-sensitive cones respectively. These cells are thus referred to as G/B type horizontal cells. Inputs from blue- and green-sensitive cones were not linearly summated, but interacted strongly at G/B type cells. G/B type cells stained intracellularly with HRP had smaller cell body and dendritic field, distinctly differing from R/G type cells.