A competitive model for spectral plasticity in the outer retina

Abstract In a previous paper, we reported that repetitive red flashes enhanced the red response of retinal luminosity-type horizontal cell (LHC) and depressed the cell's green response; repetitive green flashes suppressed the cell's red response, but caused trivial changes in its green response. Based on the idea that the spectral plasticity of the horizontal cell may reflect some changes in synaptic efficacy between the horizontal cell and various cones, a simple quantitative model was constructed. The process consists of three components: a linear first-order dynamics, a self-excitatory component within the same kind of synaptic population, and a cross-inhibitory component between different kinds of synaptic populations. It is shown that the model prediction fits reasonably well with the experimental data. The influence of relevant parameters on the model output was further inspected. Our findings suggest that there might be a competitive depression between the red- and green-cone signals that converge onto LHCs.