サルMT野における両眼性奥行き情報表現の異なった刺激更新頻度での検証

吉岡敏秀1、土井隆弘2、モハンマド・アブドラマニ1、藤田一郎1,3

 

1 大阪大学大学院・生命機能研究科

2 ペンシルバニア大学・神経科学部門

3 脳情報通信融合研究センター・大阪大学および情報通信研究機構

 

Representation of binocular depth in macaque visual area MT probed with varied temporal frequencies of visual stimuli

Toshihide Yoshioka1, Takahiro Doi2, Mohammad Abdolrahmani1, Ichiro Fujita1,3

 

1 Graduate School of Frontier Biosciences, Osaka University

2 Department of Neuroscience, University of Pennsylvania

3 Center for Information and Neural Networks, Osaka University and NICT

                                                                    Binocular disparity is a cue for binocular stereopsis. The visual system has correlation-based and match-based representations for binocular disparity. These representations are characterized by disparity tuning functions to anti-correlated RDSs (aRDSs). In aRDSs, the luminance contrasts of dots are reversed in one eye. The correlation-based representation should have inverted tuning functions for aRDSs relative to those for normal, correlated RDSs; the match-based representation should lose disparity selectivity for aRDSs. Human psychophysical experiments suggest that stimulus temporal frequency changes the relative contributions of the two representations to stereopsis. Here, we hypothesized that the temporal frequency alters the neural representation of binocular disparity in the visual cortex. To test this hypothesis, we recorded responses from 41 disparity-selective neurons in macaque middle temporal area (MT). The disparity-tuning curves of these neurons were tested both with normal and anti-correlated RDSs and with slow and fast pattern refresh rates of the RDSs. We fitted Gabor functions to the tuning curves to estimate the tuning-curve shape. For both slow and fast refresh rates, the tuning curves inverted the shapes when binocular anti-correlation was applied to RDSs. Our results suggest that temporal frequency does not alter the correlation-based representation of disparity in area MT. (COI:NO)