The normalization model is an influential model of responses of neurons in primary visual cortex. David Heeger

David Heeger

David Heeger is a contemporary neuroscientist whose research focuses on biological and artificial vision.He has made a number of influential contributions. These include a model how one can measure motion from optic flow, a nonlinear model of responses in the visual cortex called the "normalization...

 developed the model in the early 1990s, and later refined it together with Matteo Carandini

Matteo Carandini

Matteo Carandini is a contemporary neuroscientist who studies the visual system. He received a PhD in Neural Science from New York University and continued as a postdoctoral fellow at Northwestern University...

 and J Anthony Movshon. The model involves a divisive stage. In the numerator is the output of the classical receptive field

Receptive field

The receptive field of a sensory neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron. Receptive fields have been identified for neurons of the auditory system, the somatosensory system, and the visual system....

. In the denominator, a constant plus a measure of local stimulus contrast

Contrast (vision)

Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...

.