Early induced beta/gamma activity during illusory contour perception

The temporal binding hypothesis proposes that visual feature binding is achieved by neuronal synchronization. Nevertheless, the existing human neurophysiological evidence for the neuronal synchronization in visual feature binding—the oscillatory induced beta/gamma activity (IB/GA) is under suspicion. The previously observed IB/GA occurs at a later stage (after 200 ms), thus leading to the objection that IB/GA may be related to some later top-down processes rather than the early perceptual processing. However, the present EEG study identified an IB/GA as early as 90 ms after stimulus onset, which was stronger for a Kanizsa-type illusory contour (IC, a classic example of visual feature binding) than for a control stimulus. This finding provides new human evidence for the temporal binding hypothesis that neuronal synchronization occurs at the early stage of visual feature binding.