The purposes of this study were to measure areas of complete spatial summation (i.e., Ricco's area) for S- and L-cone mechanisms and to evaluate whether the sizes of Ricco's area could be explained in terms of either the densities of photoreceptors or ganglion cells. Increment thresholds were measured at the fovea and at 1.5°, 4°, 8°, and 20° in the superior retina using a temporal two-alternative forced-choice procedure. Test stimuli ranging from -0.36 to 4.61 log area (min(2)) were presented on concentric 12.3° adapting and auxiliary fields, which isolated either an S- or L-cone mechanism on the plateau of the respective threshold vs. intensity function. The data indicate that from 0-20° retinal eccentricity, the size of Ricco's area is larger for the S-cone mechanism than the L-cone mechanism, increases monotonically for the L-cone mechanism, and, for both cone mechanisms, increases between 8-20° retinal eccentricity. This latter finding suggests that ganglion cell density rather than cone density defines the size of Ricco's area in the parafoveal and peripheral retina.

中文翻译：

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Ricco 视网膜上 S 锥体和 L 锥体机制的区域。


本研究的目的是测量 S 锥体和 L 锥体机制的完整空间总和面积（即 Ricco 面积），并评估 Ricco 面积的大小是否可以用感光器或神经节细胞的密度来解释。使用颞部二选一强制选择程序测量中央凹以及上视网膜 1.5°、4°、8° 和 20° 处的增量阈值。在同心 12.3° 适应场和辅助场上呈现从 -0.36 到 4.61 对数面积（min(2)）的测试刺激，这在各自阈值与强度函数的平台上隔离了 S 或 L 锥体机制。数据表明，从 0-20° 视网膜偏心率，S 锥体机制的 Ricco 区域大小大于 L 锥体机制，L 锥体机制单调增加，并且对于两种锥体机制，Ricco 区域的大小在8-20° 视网膜偏心率。后一项发现表明，神经节细胞密度而不是视锥细胞密度决定了中央凹旁和周边视网膜中里科区域的大小。