Stromeyer C F, Gowdy P D, Chaparro A, Kronauer R E
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
Vision Res. 1999 Sep;39(18):3011-23. doi: 10.1016/s0042-6989(98)00328-9.
The red-green (RG) detection mechanism was revealed by measuring threshold detection contours in the L and M cone contrast plane for sine-wave test gratings of 0.8-6 c deg-1 on bright adapting fields of yellow or red. The slope of the RG detection contours was unity, indicating that the L and M contrast signals contribute equally (with opposite signs) on both the yellow and the red fields: this reflects first-site, cone-selective adaptation. Second-site adaptation, which may reflect saturation at a color-opponent site, was evidenced by the RG detection contours being further out from the origin of the cone contrast plane on the red field than on the yellow field. Second-site adaptation was strong (3-fold) for low spatial frequency test gratings but greatly diminished by 6 c deg-1. The disappearance of second-site adaptation with increasing spatial frequency can be explained by spatial frequency channels. The most sensitive detectors may comprise a low spatial frequency channel which is susceptible to masking by the chromatic, spatial DC component of the red field. The 6 c deg-1 patterns may be detected by a less sensitive, higher frequency channel which is less affected by the uniform red field. The RG spatial frequency channels likely arise in the cortex, implicating a partially central site for the second-site effect.
通过在黄色或红色的明亮适应场中，测量0.8 - 6 c deg-1的正弦波测试光栅在L和M锥体对比度平面上的阈值检测轮廓，揭示了红绿色（RG）检测机制。RG检测轮廓的斜率为1，表明L和M对比度信号在黄色和红色场中贡献相等（符号相反）：这反映了一级、锥体选择性适应。二级适应可能反映了颜色对立部位的饱和度，其证据是RG检测轮廓在红色场上比在黄色场上离锥体对比度平面的原点更远。对于低空间频率测试光栅，二级适应很强（3倍），但在6 c deg-1时大大减弱。随着空间频率增加，二级适应的消失可以用空间频率通道来解释。最敏感的探测器可能包括一个低空间频率通道，它容易被红色场的彩色空间直流分量掩盖。6 c deg-1的图案可能由一个不太敏感、较高频率的通道检测到，该通道受均匀红色场的影响较小。RG空间频率通道可能出现在皮层中，这意味着二级效应有部分中枢部位。
