Neurons in the visual cortex are highly sensitive to local contrast, owing to the structure of their receptive fields (e.g. adjacent ON and OFF subregions). During normal vision, the visual cortex receives widely varying average levels of contrast, illustrated in these two paintings by Claude Monet. Under some conditions, such as bright sun light, the average level of contrast may be high, while under others, such at dusk, the average level may be low. The visual system adapts to these varying levels of contrast over a period of seconds. Here we have addressed the cellular mechanisms by which this contrast adaptation takes place and conclude that a large part of if is mediated by intrinsic membrane properties of cortical neurons.
For more information, please see the following publications: Sanchez-Vives, M.V., Nowak, L.G., and McCormick, D.A. (2000) Membrane mechanisms underlying contrast adaptation in cat area 17 in vivo. J. Neurosci. 20: 4267-4285.
Sanchez-Vives, M.V., Nowak, L.G., and McCormick, D.A. (2000) Cellular mechanisms of long-lasting adaptation in visual cortical neurons in vitro. J. Neurosci., 20: 4286-4299.