Understanding the neural mechanisms of object-based visual attention

Attention depends on figure-ground organization: figures draw attention, whereas shapes of the ground tend to be ignored. We have previously shown that the visual cortex represents figure-ground organization by assigning "ownership" to contours (Zhou, Friedman & von der Heydt, J. of Neurosci. 20:6594, 2000), but how these mechanisms relate to the attention process remained unclear. In this study we show that the influences of figure-ground organization and volitional (top-down) attention converge in single neurons of area V2. We found border ownership assignment for attended and for ignored figures. Most of the border ownership selective neurons were also influenced by attention, but the attentive modulation was stronger when the attended figure was located on the neuron’s preferred side of border ownership. When the border between two overlapping figures was placed in the receptive field, responses depended on the side of attention, and enhancement was generally found on the neuron’s preferred side of border ownership. This correlation suggests that the neural network that creates figure-ground organization also provides the interface for the top-down selection process. PDF