A theoretical proposal to account for visual computation in a frog's retina.

Our theoretical account for visual computation in a frog's retina is based on the concepts that: (a) outer retinal layers provide three spatial channels of information pertaining to local spatio-temporal properties of retinal stimuli; (b) prominent specialisation in a frog's retina is the result of a non-linear lateral interaction at the inner plexiform layer; (c) ganglion cell firing frequency is determined by a local computation wherein signals from processes above are either excitatory, facilitatory or defacilitatory. General though concrete expressions for the processing at different layers are developed from these concepts. They result in a unified model for ganglion retinal cells in frog, from which the various extreme groups of ganglia can be deduced. The model leaves a natural margin to fit intermediate types, both found and likely to be found.