Kachinsky Emily S, Smith Vivianne C, Pokorny Joel
Visual Science Laboratories, University of Chicago, Chicago, IL, USA.
J Vis. 2003;3(10):599-609. doi: 10.1167/3.10.2. Epub 2003 Oct 28.
The goal of this study was to compare luminance contrast discrimination and polarity identification in the inferred Parvocellular (PC-) and Magnocellular (MC-) pathways. The position identification task tested ability to locate a contrast change within a stimulus. The polarity identification task tested ability to classify the contrast change as either brighter or darker. Three paradigms were employed to find these thresholds for the inferred MC- and PC-pathways: Pulsed-Pedestal, Steady-Pedestal and Pedestal-Delta-Pedestal. Position and polarity identification thresholds were the same for the Pulsed-Pedestal stimuli (inferred PC-pathway). The position identification thresholds were lower than the polarity identification thresholds for Steady-Pedestal stimuli (inferred MC-pathway). The position identification thresholds were lower than the polarity identification thresholds for Pedestal-Delta-Pedestal stimuli when the Delta-Pedestal contrast steps were sub-threshold or close to threshold. When the contrast steps were larger, position identification and polarity identification thresholds were similar for the Pedestal-Delta-Pedestal stimuli. Comparisons were also made between position identification and polarity identification thresholds for a short and a long stimulus presentation. There were no systematic differences dependent on presentation duration.
本研究的目的是比较推断的小细胞（PC-）和大细胞（MC-）通路中的亮度对比度辨别和极性识别。位置识别任务测试了在刺激中定位对比度变化的能力。极性识别任务测试了将对比度变化分类为更亮或更暗的能力。采用了三种范式来确定推断的MC-和PC-通路的这些阈值：脉冲-基座、稳定-基座和基座-增量-基座。对于脉冲-基座刺激（推断的PC-通路），位置和极性识别阈值相同。对于稳定-基座刺激（推断的MC-通路），位置识别阈值低于极性识别阈值。当增量-基座对比度步长低于阈值或接近阈值时，对于基座-增量-基座刺激，位置识别阈值低于极性识别阈值。当对比度步长较大时，对于基座-增量-基座刺激，位置识别和极性识别阈值相似。还对短时间和长时间刺激呈现的位置识别和极性识别阈值进行了比较。没有依赖于呈现持续时间的系统差异。
