Neuronal correlates of binocular rivalry in second-order patterns

Abstract

It has been recently reported that there is binocular rivalry in second-order patterns with a dynamic carrier [Kim et al, 2006 Journal of Vision 6(6), VSS 07, abstract 47a]. To find neuronal correlates of second-order binocular rivalry, we measured BOLD signal changes in early visual cortex while subjects viewed uncorrelated dynamic random-dot fields whose contrasts were modulated at 1.5 cycles deg-1 sine-wave with orientation of ±45°. Subjects were required to press either right or left button for alternating percepts tilted rightward or leftward, respectively. We found that there is no difference of V1 activity in both hemispheres when either right or left response was made. However, there was a fluctuation of activity in V2 for alternating percepts. V2 activity increased with the right response and decreased with the left response in the left hemisphere, while the activity pattern was reversed in the right hemisphere. These results indicate that V2 area is a special site for second-order binocular processing as suggested in form and motion vision.