Difference of Gaussians (DOG) model.

(A) The center-surround receptive filed organization is assumed to be fitted by two Gaussian curves: the narrower positive Gaussian representing the excitatory center or the CRF, while the broader negative Gaussian represents the inhibitory surround or the nCRF. Ke and a represent the strength and the space constants for the CRF, and Ki and b, those of the nCRF. The summation profile (R) of the model is represented as the difference of the two integrals of Gaussians. (B) A V1 neuron with suppressive summation. Dashed and dotted curves represent integrals of the excitatory and inhibitory components and the solid curve the linear combination of the two components that best fits the summation data.