Extraclassical Responses in V1 Modeled via Modulated Cortical Conductances

Two competing phenomological models of extraclassical spatial summation in V1 are the Differenceof-Gaussians (DoG) and the Ratio-of-Gaussians (RoG) which argue for subtractive or divisive normalization, respectively, as the basis for a variety of extraclassical response properties, such as surround suppression and contrast-dependent receptive field growth. Problematic with these models, however, is that they are somewhat removed from the neurophysiology and thus do not lend themselves to inferring underlying mechanisms. Simulations of an anatomically and physiologically detailed large-scale spiking neuron model, which we have previous developed [1], indicate that the interaction between excitatory and inhibitory cortical conductances may be at the root of the these extraclassical phenomena and that both subtractive and divisive effects of cortical inhibition are involved. Moreover, Anderson et al showed, using intracellular recordings from cat, that cortical conductances are oscillatory [2], with stronger modulation in the inhibitory conductance. Based on these two observations, we developed a