The Journal of Neuroscience, May 9, 2007, 27(19):5063-5067; doi:10.1523/JNEUROSCI.0835-07.2007
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Brief Communications
Responses of Neurons in Primary Visual Cortex to Transient Changes in Local Contrast and Luminance
Wilson S. Geisler,
Duane G. Albrecht, and
Alison M. Crane
Center for Perceptual Systems and Department of Psychology, University of Texas at Austin, Austin, Texas 78712
Correspondence should be addressed to Wilson S. Geisler, The University of Texas at Austin, Center for Perceptual Systems, 108 East Dean Keeton, 1 University Station A8000, Austin, TX 78712-0187. Email: geisler{at}psy.utexas.edu
During normal saccadic inspection of natural images, the receptive fields of cortical neurons are bombarded with frequent simultaneous changes in local mean luminance and contrast, yet there have been no systematic studies of how cortical neurons respond to such stimulation. The responses of single neurons in the primary visual cortex of the cat were measured for 200 ms presentations of sine-wave gratings confined to the conventional receptive field. Both local mean luminance and contrast were parametrically and randomly varied over the 11.5 log unit ranges that are typical of natural images. We find that responses are strongly modulated by both the local mean luminance and contrast, but in an approximately separable manner: the contrast response function is approximately invariant except for a scale factor that depends on the local mean luminance. The shape of the temporal response profiles were found to be approximately invariant with contrast, but were strongly affected by the local mean luminance. The results suggest that most, if not all, cortical neurons carry substantial local luminance information.
Key words: visual cortex; contrast response; luminance response; transient stimulation; neural coding; natural scene statistics
Received Nov. 26, 2006;
revised April 3, 2007;
accepted April 4, 2007.
Correspondence should be addressed to Wilson S. Geisler, The University of Texas at Austin, Center for Perceptual Systems, 108 East Dean Keeton, 1 University Station A8000, Austin, TX 78712-0187. Email: geisler{at}psy.utexas.edu