Brain activities in the human visual areas while viewing illusory contours - an fMRI study

摘要

The Kanizsa figure yields illusory contours that bridge gaps between precisely aligned luminance edges of the inducers (packmans). Using fMRI, we investigated cortical processing of the Kanizsa-type illusory contours in human visual areas. By changing orientations of the packmans, we controlled the percept of the illusory contours which appeared only while the luminance edges of the packmans were aligned. Through the experiment, there was no local modulation of luminance in the stimulus. The distribution of brain activities evoked by illusory contours were quite similar to that evoked by the real contours: there were robust activations in the striate cortex as well as extrastriate cortex. Surprisingly, the involvement of striate cortex was also observed for inducers which yields little or no illusory contour. We discussed the results in terms of retinotopy, and cortical formation of contours and figures.