PDF(Pubmed)
Abstract：
Recognizing faces regardless of their viewpoint is critical for social interactions. Traditional theories hold that view-selective early visual representations gradually become tolerant to viewpoint changes along the ventral visual hierarchy. Newer theories, based on single-neuron monkey electrophysiological recordings, suggest a three-stage architecture including an intermediate face-selective patch abruptly achieving invariance to mirror-symmetric face views. Human studies combining neuroimaging and multivariate pattern analysis (MVPA) have provided convergent evidence of view selectivity in early visual areas. However, contradictory conclusions have been reached concerning the existence in humans of a mirror-symmetric representation like that observed in macaques. We believe these contradictions arise from low-level stimulus confounds and data analysis choices. To probe for low-level confounds, we analyzed images from two face databases. Analyses of image luminance and contrast revealed biases across face views described by even polynomials-i.e., mirror-symmetric. To explain major trends across neuroimaging studies, we constructed a network model incorporating three constraints: cortical magnification, convergent feedforward projections, and interhemispheric connections. Given the identified low-level biases, we show that a gradual increase of interhemispheric connections across network-layers is sufficient to replicate view-tuning in early processing stages and mirror-symmetry in later stages. Data analysis decisions-pattern dissimilarity measure and data recentering-accounted for the inconsistent observation of mirror-symmetry across prior studies. Pattern analyses of human fMRI data (of either sex) revealed biases compatible with our model. The model provides a unifying explanation of MVPA studies of viewpoint selectivity and suggests observations of mirror-symmetry originate from ineffectively normalized signal imbalances across different face views.
摘要：
无论他们的观点如何，识别面孔对于社交互动至关重要。传统理论认为，视图选择性的早期视觉表示逐渐容忍沿腹侧视觉层次结构的观点变化。较新的理论，基于单神经元猴电生理记录，建议一个三阶段的体系结构，包括一个中间的面部选择补丁突然实现镜像对称的面部视图的不变性。结合神经影像学和多变量模式分析（MVPA）的人体研究为早期视觉区域的视野选择性提供了一致的证据。然而,已经得出了矛盾的结论，关于人类存在的镜像对称表示，就像在猕猴中观察到的那样。我们认为，这些矛盾来自低水平的刺激困惑和数据分析选择。为了调查低水平的困惑，我们分析了来自两个人脸数据库的图像。对图像亮度和对比度的分析揭示了由偶数多项式描述的人脸视图的偏差，即镜像对称。为了解释神经影像学研究的主要趋势，我们构建了一个包含三个约束的网络模型：皮质放大，收敛前馈投影，和半球间的联系。鉴于已确定的低水平偏见，我们表明，跨网络层的半球间连接逐渐增加足以在早期处理阶段复制视图调整，并在后期复制镜像对称。数据分析决策-模式差异度量和数据重新定位-解释了先前研究中对镜像对称性的不一致观察。对人类fMRI数据（任一性别）的模式分析显示出与我们的模型兼容的偏见。该模型为观点选择性的MVPA研究提供了统一的解释，并表明对人类镜像对称的观察源于不同人脸视图中无效归一化的信号失衡。重要性陈述无论观点如何，对身份的识别对于社会互动至关重要。在灵长类动物中，镜像对称人脸视图的表示被认为是从严格调整视图到视点不变表示的关键中间处理步骤。人体神经影像学研究,然而,在面部选择区域的观点信息表示方面得出了矛盾的结论，尽管在早期视觉区域是一致的。我们证明了低水平刺激的混淆和数据分析选择解释了这些矛盾的观察结果。我们提出了一个网络模型，该模型在早期处理阶段复制视图调整的观察结果，而不考虑分析选择。通过选择模式差异度量和数据重新定位来解释后期对镜像对称的可变观察。对功能磁共振成像数据的分析证实了偏见与我们的模型广泛兼容。
