Perrett D I, Oram M W
Psychological Laboratory, St. Andrews University, Scotland, UK.
Z Naturforsch C J Biosci. 1998 Jul-Aug;53(7-8):518-41. doi: 10.1515/znc-1998-7-807.
A model of recognition is described based on cell properties in the ventral cortical stream of visual processing in the primate brain. At a critical intermediate stage in this system, 'Elaborate' feature sensitive cells respond selectively to visual features in a way that depends on size (+/- 1 octave), orientation (+/- 45 degrees) but does not depend on position within central vision (+/- 5 degrees). These features are simple conjunctions of 2-D elements (e.g. a horizontal dark area above a dark smoothly convex area). They can arise either as elements of an object's surface pattern or as a 3-D component bounded by an object's external contour. By requiring a combination of several such features without regard to their position within the central region of the visual image, 'Pattern' sensitive cells at higher levels can exhibit selectivity for complex configurations that typify objects seen under particular viewing conditions. Given that input features to such Pattern sensitive cells are specified in approximate size and orientation, initial cellular 'representations' of the visual appearance of object type (or object example) are also selective for orientation and size. At this level, sensitivity to object view (+/- 60 degrees) arises because visual features disappear as objects are rotated in perspective. Processing is thus viewer-centred and the neurones only respond to objects seen from particular viewing conditions or 'object instances'. Combined sensitivity to multiple features (conjunctions of elements) independent of their position, establishes selectivity for the configurations of object parts (from one view) because rearranged configurations of the same parts yield images lacking some of the 2-D visual features present in the normal configuration. Different neural populations appear to be selectively tuned to particular components of the same biological object (e.g. face, eyes, hands, legs), perhaps because the independent articulation of these components gives rise to correlated activity in different sets of input visual features. Generalisation over viewing conditions for a given object can be established by hierarchically pooling outputs of view-condition specific cells with pooling operations dependent on the continuity in experience across viewing conditions. Different object parts are seen together and different views are seen in succession when the observer walks around the object. The view specific coding that characterises the selectivity of cells in the temporal lobe can be seen as a natural consequence of selective experience of objects from particular vantage points. View specific coding for the face and body also has great utility in understanding complex social signals, a property that may not be feasible with object-centred processing.
本文描述了一种基于灵长类动物大脑视觉处理腹侧皮质流中细胞特性的识别模型。在该系统的一个关键中间阶段，“精细”特征敏感细胞以一种依赖于大小（±1倍频程）、方向（±45度）但不依赖于中央视觉范围内位置（±5度）的方式对视觉特征进行选择性响应。这些特征是二维元素的简单组合（例如，一个黑暗平滑凸起区域上方的水平黑暗区域）。它们既可以作为物体表面图案的元素出现，也可以作为由物体外部轮廓界定的三维组件出现。通过要求几个这样的特征组合，而不考虑它们在视觉图像中心区域内的位置，更高层次的“图案”敏感细胞可以对在特定观察条件下看到的典型物体的复杂配置表现出选择性。鉴于输入到此类图案敏感细胞的特征是按近似大小和方向指定的，物体类型（或物体示例）视觉外观的初始细胞“表征”也对方向和大小具有选择性。在这个层面上，对物体视图（±60度）的敏感性出现是因为当物体在透视中旋转时视觉特征会消失。因此，处理是以观察者为中心的，神经元仅对从特定观察条件或“物体实例”看到的物体做出反应。对多个特征（元素的组合）的组合敏感性，独立于它们的位置，建立了对物体部分配置（从一个视图）的选择性，因为相同部分的重新排列配置会产生缺乏正常配置中存在的一些二维视觉特征的图像。不同的神经群体似乎被选择性地调整到同一生物物体的特定组件（例如，面部、眼睛、手、腿），这可能是因为这些组件的独立关节运动会在不同组的输入视觉特征中产生相关活动。对于给定物体在不同观察条件下的泛化可以通过分层汇总特定视图条件细胞的输出，并通过依赖于不同观察条件下经验连续性的汇总操作来建立。当观察者围绕物体走动时，会一起看到不同的物体部分，并相继看到不同的视图。颞叶中细胞选择性的视图特定编码可以被视为从特定有利位置对物体进行选择性体验的自然结果。面部和身体的视图特定编码在理解复杂社会信号方面也具有很大的实用性，这一特性对于以物体为中心的处理可能是不可行的。
