Kinetics of synaptic transmission from photoreceptors to horizontal and bipolar cells in turtle retina.

The kinetics of synaptic transfer from photoreceptors to second order neurons have been determined in the retina of the snapping turtle. Analysis of the fluctuations resulting from the random release of cone transmitter molecules reveals that the action on postsynaptic channels of the depolarizing bipolar cells is prolonged by approximately 10 times compared to the action on the hyperpolarizing bipolar cells. Determination of the cone and rod to horizontal cell impulse response shows that the kinetics of the cone/H1AT synapse is approximately 8-10 times shorter than the rod/H1AT synapse. These results indicate that the cone driven, sign preserving synapses exhibit comparable temporal characteristics.