Verhoef Bram-Ernst, Bohon Kaitlin S, Conway Bevil R
Department of Neurobiology, University of Chicago, Chicago, Illinois 60637, Laboratorium voor Neuro-en Psychofysiologie, KU Leuven, Campus Gasthuisberg, BE 3000 Leuven, Belgium.
Neuroscience Program Wellesley, Wellesley College, Wellesley, Massachusetts 02481, and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
J Neurosci. 2015 Apr 29;35(17):6952-68. doi: 10.1523/JNEUROSCI.5079-14.2015.
Binocular disparity is a powerful depth cue for object perception. The computations for object vision culminate in inferior temporal cortex (IT), but the functional organization for disparity in IT is unknown. Here we addressed this question by measuring fMRI responses in alert monkeys to stimuli that appeared in front of (near), behind (far), or at the fixation plane. We discovered three regions that showed preferential responses for near and far stimuli, relative to zero-disparity stimuli at the fixation plane. These "near/far" disparity-biased regions were located within dorsal IT, as predicted by microelectrode studies, and on the posterior inferotemporal gyrus. In a second analysis, we instead compared responses to near stimuli with responses to far stimuli and discovered a separate network of "near" disparity-biased regions that extended along the crest of the superior temporal sulcus. We also measured in the same animals fMRI responses to faces, scenes, color, and checkerboard annuli at different visual field eccentricities. Disparity-biased regions defined in either analysis did not show a color bias, suggesting that disparity and color contribute to different computations within IT. Scene-biased regions responded preferentially to near and far stimuli (compared with stimuli without disparity) and had a peripheral visual field bias, whereas face patches had a marked near bias and a central visual field bias. These results support the idea that IT is organized by a coarse eccentricity map, and show that disparity likely contributes to computations associated with both central (face processing) and peripheral (scene processing) visual field biases, but likely does not contribute much to computations within IT that are implicated in processing color.
双眼视差是物体感知中一种强大的深度线索。物体视觉的计算在颞下叶皮质（IT）达到顶峰，但IT中视差的功能组织尚不清楚。在这里，我们通过测量警觉猴子对出现在注视平面之前（近）、之后（远）或注视平面上的刺激的功能磁共振成像（fMRI）反应来解决这个问题。我们发现了三个区域，相对于注视平面上的零视差刺激，它们对近和远刺激表现出优先反应。这些“近/远”视差偏向区域位于背侧IT内，正如微电极研究所预测的那样，并且位于颞下回后部。在第二项分析中，我们改为将近刺激的反应与远刺激的反应进行比较，发现了一个单独的“近”视差偏向区域网络，该网络沿着颞上沟的嵴延伸。我们还在同一批动物中测量了fMRI对不同视野偏心度下的面孔、场景、颜色和棋盘状环的反应。在任何一项分析中定义的视差偏向区域都没有表现出颜色偏向，这表明视差和颜色在IT内参与不同的计算。场景偏向区域对近和远刺激优先做出反应（与没有视差的刺激相比），并且具有外周视野偏向，而面孔区域具有明显的近偏向和中央视野偏向。这些结果支持了IT由粗略的偏心度图谱组织的观点，并表明视差可能有助于与中央（面孔处理）和外周（场景处理）视野偏向相关的计算，但可能对IT内与颜色处理相关的计算贡献不大。
