Different spatial tunings for ON and OFF pathway stimulation.
Different spatial tunings for ON and OFF pathway stimulation.
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ON 和 OFF 通路刺激的不同空间调谐。
DOI：
10.1111/j.1475-1313.1992.tb00297.x
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Liu,L
中科院分区：
文献类型：
--
作者：
Tyler,CW;Chan,H;Liu,L
我们比较了三种类型的本地化的刺激呈现与平滑的时空包络的亮度增量和减量的敏感性的空间调谐。第一种类型由具有亮度正偏置或负偏置的时空Gabor光栅函数组成。对于正的Gabor，空间调谐显示出显著更窄的带宽和更大的峰值灵敏度。类似的描述可以应用于具有2-D高斯差分分布的斑点的检测结果，尽管调谐函数的形状在几个方面不同。我们还在n对比度自掩蔽范例中使用了有偏的Gabor调制，其中增量（或减量）在具有相同空间配置的稳定背景下呈现，在一定范围的基础对比度上。在中等空间频率下，偏置掩蔽函数类似于通常针对无偏光栅发现的那些，在低对比度下显示阈值促进（勺形），并且在较高对比度下显示亚韦伯掩蔽行为。然而，在低空间频率下，出现了明显的不对称性。具有正仓的刺激再次表现出典型的掩蔽行为，但是对于负偏置刺激获得了几乎平坦的掩蔽函数。我们的结论是，没有突然的亮度瞬变的刺激揭示了显着的差异，在空间调谐的反应，积极和消极的刺激，这可能反映了在ON和OFF处理系统的神经连接的差异。
We compared the spatial tuning of sensitivity to luminance increments and decrements in three types of localized stimulus presentation with a smooth spatiotemporal envelope. The lirst type consisted of spatiotemporal Gabor grating functions with either a positive or a negative bias in luminance, The spatial tuning showed a substantially narrower bandwidth and greater peak sensitivity for the positive Gabors. A similar description could be applied to the results for detection of spots with a 2‐D difference‐of‐Gaussian profile, although the shape of the tuning function differed in several respects. We also used the biased Gabor modulation in n contrast self‐masking paradigm, where the increment (or decrement) was presented against a steady background with the same spatial configuration, over a range of base contrasts. At medium spatial frequencies the biased masking functions were similar to those typically found for unbiased gratings, in showing a threshold facilitation (dipper) at low contrast, and sub‐Weber masking behaviour at higher contrasts. At low spatial frequencies, however, a pronounced asymmetry appeared. Stimuli with a positive bins again showed typical masking behaviour, but a virtually flat masking function was obtained for negative bias stimuli. We conclude that stimuli without abrupt luminance transients reveal pronounced differences in the spatial tuning of responses to positive and negative stimuli, which probably reflect differences in the neural connectivity of the ON and OFF processing systems.