Surrounding Size effect on Brightness Contrast-to-Assimilation is Predicted in Retina

TitleSurrounding Size effect on Brightness Contrast-to-Assimilation is Predicted in Retina
Publication TypeJournal Article
Year of Publication2015
AuthorsKim J, Bertalmío M
Journal*Submitted* to Journal of Vision
Brightness (perceived luminance) of a target area in a visual scene depends on luminance of the surfaces surrounding this area (brightness induction). The quantity and quality of the induction are further altered by the size of the surrounding surfaces such that a large surrounding surface induces strong contrast onto the target area but a small surface induces weak contrast or assimilation. While contrast induction is attributed to a local-range lateral inhibition in the retina, there is little consensus on a neural structure underlying assimilation. Some studies postulated that assimilation occurs by an unknown post-retinal mechanism that performs long-range surface interaction. However, we propose that such long-range mechanism exists in the retina based on recent neurophysiological evidence that the main retinal inhibitory feedback interneurons manifest wide receptive-fields (RFs). We cross-examined the effect of these wide RFs in two different biophysical retinal model platforms (van Hateren, 2005; 2007; Wilson, 1997) and confirmed that the cell responses in both of the models match to behavioral data of the brightness contrast and assimilation as a function of surrounding surface size (Helson, 1963; Reid & Shapley, 1988), if and only if the wide RFs are considered. To the best of the authors' knowledge, this is the first evidence that the wide RFs of inhibitory interneurons serve for long-range surface interaction, that local contrast and long-range surface interaction share the same neural locus, and that brightness assimilation is inaugurated at the retinal level.