Dynamics of perceptual oscillations in form vision

Certain periodic dot patterns (Marroquin patterns) generate a percept of dy namically oscillating circles, and analogous effects were explored by op ar tists in the 1960s. Here we show psychophysically that circles are perceive d in these patterns only around specific points that are quantitatively pre dicted by a neural model of configural units hypothesized to reside in cort ical area V4. Circles superimposed on the pattern mask perception of illuso ry circles. A neural model of lateral inhibitory interactions among V4 conf igural units showing spike-frequency adaptation quantitatively accounts for the human data. The model is consistent with ideas on the neural basis of attention in V4, and it suggests that attention may be biased via neuromodu lation of slow hyperpolarizing potentials in cortical neurons.