The direction of figure is determined by asymmetric surrounding suppression/facilitation

Many neurons in monkeys' V2 and V4 are selective for border ownership (BO) [H. Zhou, H.S. Friedman, R. von der Heydt, Coding of border ownership in monkey visual cortex, J. Neurosci. 20 (2000) 6594-6611). We have developed a computational model for the BO determination of the neurons based on their contextual modulation. Our model consists of hundreds of model cells with distinct surround suppressive/facilitatory regions that are generated by a linear combination of Gaussians. The simulation results show that many model cells realize the major characteristics of BO selective neurons. Investigating the surrounding regions of the BO selective model cells with perfect consistency, we found that their iso orientation suppression is dominant over the cross orientation facilitation, which agrees quantitatively with physiological reports. These results suggest that the surrounding modulation is a fundamental mechanism for BO selectivity.