Binocular disparity selectivity to anti-correlated random-dot stereograms is reduced in monkey V4

2S. Tanabe, 2K. Umeda, and 1I. Fujita

1Lab. for Cogn. Neurosci., Grad. Sch. of Frontier Biosciences and 2Grad. Sch. of Engineering Science, Osaka Univ., Toyonaka, Osaka, 560-8531

By reversing the contrast of dots seen by one of the eyes in a random-dot stereogram (RDS) to generate an anti-correlated RDS, the perception of depth is diminished. We exploited this perceptual phenomenon as tool for testing whether neural responses in V4 correlate with the perception of stereoscopic depth. We examined 92 V4 neurons in three awake, fixating monkeys. Thirty-five cells were sensitive to disparity in correlated RDSs covering their receptive fields. The majority of these cells (26/35) lost their selectivity for disparity when the RDS was anti-correlated. Disparity tuning to anti-correlated stimuli tended to be more reduced for cells with higher disparity sensitivity. Our results suggest that V4 is involved in the processing of binocular correspondence to form the stereoscopic perception of depth.