Two-dimensional modeling of visual receptive fields using Gaussian subunits.

Retinal ganglion cell receptive fields have been successfully described using the difference of Gaussians model introduced by Rodieck. As the basic elements of retinal receptive fields are well described by the Gaussian function, it is natural to model receptive fields beyond this level as a convergence of Gaussian subunits. In this paper the full two-dimensional solution to the problem of calculating the response to drifting gratings of a model receptive field composed of Gaussian subunits is presented. The subunits are not required to be radially symmetric, any number is allowed, with any temporal phase delays; and responses are predicted to gratings of any spatial frequency at any orientation. This solution will greatly extend the range of receptive fields that can be modeled as a convergence of Gaussian subunits, including those with orientational and directional selectivities.