A model with nonlinearity of the photoreceptor presynaptic membrane as its important distinguishing feature was created on the basis of the hypothesis that feedback between the horizontal cells and photoreceptors is effected by a current generated by the subsynaptic membrane of the horizontal cells and leaking partly into the photoreceptors. Measurements with the model also reproduced experimental observations such as depolarization of the cone during hyperpolarization of the horizontal cell in response to the showing of a ring of light or passage of an electric current, and also certain special features of the current-voltage curves of the cones.