Sereno M I, McDonald C T, Allman J M
Cognitive Science, University of California at San Diego, La Jolla 92093-0515.
Cereb Cortex. 1994 Nov-Dec;4(6):601-20. doi: 10.1093/cercor/4.6.601.
Two new techniques for analyzing retinotopic maps--arrow diagrams and visual field sign maps--are demonstrated with a large electrophysiological mapping data set from owl monkey extrastriate visual cortex. An arrow diagram (vectors indicating receptive field centers placed at cortical coordinates) provides a more compact and understandable representation of retinotopy than does a standard receptive field chart (accompanied by a penetration map) or a double contour map (e.g., isoeccentricity and isopolar angle as a function of cortical x, y-coordinates). None of these three representational techniques, however, make separate areas easily visible, especially in data sets containing numerous areas with partial, distorted representations of the visual hemifield. Therefore, we computed visual field sign maps (non-mirror-image vs mirror-image visual field representation) from the angle between the direction of the cortical gradient in receptive field eccentricity and the cortical gradient in receptive field angle for each small region of the cortex. Visual field sign is a local measure invariant to cortical map orientation and distortion but also to choice of receptive field coordinate system. To estimate the gradients, we first interpolated the eccentricity and polar angle data onto regular grids using a distance-weighted smoothing algorithm. The visual field sign technique provides a more objective method for using retinotopy to outline multiple visual areas. In order to relate these arrow and visual field sign maps accurately to architectonic features visualized in the stained, flattened cortex, we also developed a deformable template algorithm for warping the photograph-derived penetration map using the final observed location of a set of marking lesions.
利用来自枭猴纹外视觉皮层的大量电生理图谱数据集，展示了两种用于分析视网膜拓扑图的新技术——箭头图和视野符号图。与标准感受野图（附带穿透图）或双轮廓图（例如，作为皮层x、y坐标函数的等偏心率和等极角）相比，箭头图（将感受野中心的向量置于皮层坐标上）能提供更紧凑且易于理解的视网膜拓扑表示。然而，这三种表示技术均无法使不同区域轻易可见，尤其是在包含众多区域的数据集里，这些区域对视觉半视野的表示存在部分扭曲。因此，我们通过计算皮层每个小区域中感受野偏心率的皮层梯度方向与感受野角度的皮层梯度之间的夹角，得出了视野符号图（非镜像与镜像视野表示）。视野符号是一种局部测量值，对皮层图的方向和扭曲以及感受野坐标系的选择均具有不变性。为了估计梯度，我们首先使用距离加权平滑算法将偏心率和极角数据内插到规则网格上。视野符号技术为利用视网膜拓扑勾勒多个视觉区域提供了一种更客观的方法。为了将这些箭头图和视野符号图准确地与在染色、展平的皮层中可视化的结构特征相关联，我们还开发了一种可变形模板算法，利用一组标记损伤的最终观测位置来扭曲源自照片的穿透图。
