Long-range sensitization in the vertebrate retina and human perception

Sensory stimuli have extensive correlations, which should be exploited by an efficient detector of specific sensory features according to theoretical principles. Here we show that visual stimulation far outside the classical receptive field center causes ganglion cells to subsequently increase their sensitivity to local stimuli in a process we term long-range sensitization. This increased sensitivity improves detection and discrimination of weak stimuli and exhibits pattern specificity, increasing sensitivity more when peripheral and central stimuli share spatial frequency statistics. This process requires input from wide-field, nonlinear inhibitory amacrine cells, supporting a simple circuit model that reproduces sensitization. We further show that long-range sensitization parallels a novel perceptual effect in humans, in which surround stimulation subsequently improves discrimination of a small central stimulus. We conclude that the retina uses long-range statistics of the visual world to better encode local visual features, and that such improved encoding may play a role in perception.