Visual world consists of many objects. Each object has its own visual features (e.g. color, position, motion and shape). In early visual processing stages, visual features are processed in relatively independent ways. However, in late processing stages, a fundamental challenge for the visual system is to integrate visual features into correct objects, rather than non-existent objects, known as the binding problem. Professor Anne Treisman at the Psychology Department of Princeton University, 2011 National Medal of Science Laureate, proposed the influential Feature Integration Theory in 1982 to explain the binding mechanisms. Although her theory received a lot of support from psychological studies, neuroscientific evidence is still scarce. A major obstacle to unraveling the neural mechanisms of feature binding is the difficulty in inducing a reliable and active binding process in the brain. A steady-state misbinding phenomenon of color and motion reported inNature(2004) provides a unique opportunity to solve this problem. 

Fang Fang’s lab took advantage of this phenomenon and found that adapting to this illusion could generate another illusion (color-contingent motion aftereffect)! This psychophysical observation is not only intriguing by itself, but also tells us that the misbound features could be coded in visual cortex. Further, using the fMRI adaptation technique and advanced effective-connectivity (DCM) analyses, we showed that the misbinding took place in area V2, which was caused by the reentrant processes from areas V4 and V5. To the best of our knowledge, these findings, for the first time, provide direct and strong evidence for active feature binding in early visual cortex and for a critical role of reentrant connections from specialized extrastriate areas to early visual cortex in feature binding, both of which are central components of the Feature Integration Theory and other modern feature binding theories. 

Xilin Zhang, Jiang Qiu, Yanyu Zhang, Shihui Han and Fang Fang. Misbinding of color and motion in human visual cortex.  Current Biology  24, 1354–1360, June 16, 2014