Simulation Analysis of the Photoresponse in Retinal Rods

Abstract

Retinal rod photoreceptors in the eyes play a role in the first steps of the visual information processing and convert light into neural signals. In recent years, mathematical models of phototransduction mechanism in the outer segment(OS) of the rod have been developed and applied to analyze the biophysical processes. Although the membrane potential is responsible for sending messages to second order neurons generated in the inner segment(IS), the membrane electrical properties of IS have not been well modeled yet.

In this study, in order to clarify the function of the rod, we integrate the multiscale properties into a model. The model is based on the previous studies, i.e., the model of the OS (Dell'Orco et al.) and the model of the IS (Kamiyama et al., Publio et al.). To evaluate the model, the photocurrent in the OS and photovoltage in the IS were analyzed under a variety of conditions, including effects by channel blockers and the mutaion of retinal pigment epithelium (RPE). As a result, the model reproduced the photoresponses observed in the previous studies.