Computer Analysis of Spatial Integration in Vertebrate Retinal Horizontal Cells

A model is developed for the electrically coupled horizontal cells of the vertebrate retina. The model consists of a weighted distributed-parameter network in which the elements have direct cellular significance: transmembrane conductance and capacitance, and radial coupling resistance. Membrane polarization is viewed as a change in the overall membrane conductance in response to photoreceptor influence. Model simulation is implemented on a computer using a circuit analysis program. As a structural representation of the S-space, the model accurately spreads potential, but fails to integrate photoreceptor activity spatially like the S-space. It has been suggested that retinal scattering is the cause of this discrepancy, but the analysis here indicates that photoreceptor coupling is probably the major influence.