Heeger DJ, Normalization of cell responses in cat striate cortex, Visual Neuroscience, 9:181-198, 1992.
Abstract: Simple cells in striate cortex have been depicted as halfwave-rectified linear operators. Complex cells have been depicted as energy mechanisms, constructed from the squared sum of the outputs of quadrature pairs of linear operators. However, the linear/energy model falls short of a complete explanation of striate cell responses. In this paper, I present a modified version of the linear/energy model in which striate cells mutually inhibit one another, effectively normalizing their responses with respect to stimulus contrast. This paper reviews experimental measurements of striate cell responses, and shows that the new model explains a significantly larger body of physiological data.