An intracellular recording made from the retinal luminosity horizontal cell (LHC) demonstrated that repetitive red flashes enhanced the cell's responsiveness to red stimulus and depressed its responsiveness to green stimulus and that repetitive green flashes suppressed the cell's red response but produced little change in its green response. Based on the idea that the spectral plasticity of LHCs may reflect some synaptic efficacy changes between the LHC and various cones, a self-organizing system is proposed to investigate the possible manner of information processing and storage within the synapses. The results of model analysis suggest that the stimulus-pattern-related spectral plasticity is attributable to the excitatory interaction within the same kinds of synapses and the inhibitory interaction between different kinds of synapses. This system is able to encode and store the history of signal transmission in a graded and cumulative fashion.