Lee B B, Wehrhahn C, Westheimer G, Kremers J
Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Vision Res. 1995 Oct;35(19):2743-58. doi: 10.1016/0042-6989(95)00015-r.
Responses of parafoveal macaque ganglion cells were measured as a function of the contrast and position of an edge flashed within their receptive fields. The goal was to determine the ability of different cell types to signal edge location. For comparison, parafoveal vernier thresholds of human observers were measured with pairs of flashed edges. Cells of the magnocellular (MC-) pathway gave larger responses than cells of the parvocellular (PC-) pathway. Neurometric analyses comparing a cell's response at different edge positions were performed. The positional signal from single MC-pathway cells was more precise than from PC-pathway cells, especially at lower contrasts. In a second analysis, based on the neurophysiological results, responses from a matrix of ganglion cells were generated. Using a simple model, vernier performance expected from such a matrix was predicted as a function of edge length and contrast. Again, the MC-pathway gave a more precise positional signal than the PC-pathway despite the latter's numerical advantage. At contrasts of 20% and below, only the MC-pathway would appear capable of supporting vernier performance with our stimuli. At higher contrasts either the MC- or PC-pathway could provide an adequate signal.
测量了恒河猴副中央凹神经节细胞的反应，该反应是其感受野内闪烁边缘的对比度和位置的函数。目的是确定不同细胞类型对边缘位置进行信号传递的能力。为作比较，用成对的闪烁边缘测量了人类观察者的副中央凹游标阈值。大细胞（MC）通路的细胞比小细胞（PC）通路的细胞反应更大。进行了神经测量分析，比较细胞在不同边缘位置的反应。单个MC通路细胞的位置信号比PC通路细胞的更精确，尤其是在较低对比度时。在第二项分析中，基于神经生理学结果，生成了神经节细胞矩阵的反应。使用一个简单模型，预测了这样一个矩阵在不同边缘长度和对比度下的游标性能。同样，尽管PC通路在数量上占优势，但MC通路给出的位置信号更精确。在20%及以下的对比度下，只有MC通路似乎能够支持我们的刺激下的游标性能。在较高对比度下，MC或PC通路都可以提供足够的信号。
