Abstract
Retinal cone photoreceptors initiate the visual information processing by converting the light into electrical signals. The cones transmit the signal to horizontal cells and bipolar cells using glutamate as the neurotransmitter. The negative feedback from horizontal cell to cones is thought to affect the glutamate release from cones. Cone responds with an initial hyperpolarization and a delayed depolarization to a flash of light. The response dynamics is changed by the pattern and the stimulus intensity but the depolarizing response can be attributed to the feedback from HCs. The purpose of this study is to analyze the mechanism how the feedback contributes to the cone/HC interaction.We developed a mathematical model of cone-HC network, which describes the intracellular signal transduction and ionic mechanisms of the cells. The feedback was assumed to regulate calcium current in the cone synapse.We simulated cone photoresponses with/without the feedback from the HC. Our results showed similar light responses to those observed experimentally, and suggested that the feedback induces a characteristic depolarization of cone by increasing inward current.
