著者：Hiroshi Shiozaki, Seiji Tanabe, Takahiro Doi, Ichiro Fujita
タイトル：Choice-predictive activity in macaque area V4 during fine discrimination of stereoscopic depth
発表日：28 Jul., 2009
アブストラクト：Binocular disparity is represented in a number of areas in the primate visual cortex, yet the contribution of each area to stereopsis has not been fully clarified. Area MT in the dorsal visual pathway contributes to coarse but not fine disparity discrimination, meaning other areas are responsible for fine depth perception.
We examined whether the disparity signal in area V4, an intermediate stage in the ventral visual pathway, is such an area. We recorded single V4 neuron activity while a Japanese monkey reported whether the center region of a random-dot stereogram was perceived as nearer or farther than its adjacent surround. The disparity of the center region relative to the surround varied across trials. The range of disparity covered the monkey's psychophysical threshold. Neuronal activities during stimulus presentation were predictive of the monkey's choice on a trial-by-trial basis. One-third of the tested cells (12/35) significantly predicted the behavioral choice, which we quantified as choice probability. The sign of the predicted choice was consistent with the monkey's subsequent choice. We suggest that V4 cells contribute to fine disparity discrimination by signaling the sign of their preferred disparity with the spike count.