Hawryshyn C W
Department of Biology, University of Victoria, British Columbia, Canada.
Vis Neurosci. 1991 Apr;6(4):293-301. doi: 10.1017/s0952523800006544.
The light-adaptation properties of goldfish photoreceptor mechanisms were examined using Stiles' two-color threshold technique. Threshold vs. background intensity (TVI) curves were determined for isolated cone and rod mechanisms using the heart-rate conditioning technique. The principal aim of this study was to compare the light-adaptation properties of the ultraviolet (UV)-sensitive cone mechanism to the other receptor mechanisms of goldfish. This examination revealed several striking functional differences: (1) The UV-sensitive cone mechanism threshold vs. background intensity (TVI) exhibited a slope of 0.65 (compared to the approximate 1.0 for the other cone mechanisms on a log/log plot) and thus was not in accordance with Weber's law. This may in part be related to the intrusion of the blue-sensitive mechanism at the upper radiance range. (2) The operation of the UV-sensitive cone mechanism was limited to intermediate intensities (i.e. not very dim or bright). (3) The UV-sensitive cone mechanism exhibited a Weber fraction or luminance contrast threshold of 0.316 that was approximately six times larger than the other cone mechanisms but comparable to the rod mechanism. This indicates that the UV-sensitive cone mechanism performs relatively poorly in terms of brightness contrast detection.
利用斯泰尔斯双色阈值技术研究了金鱼光感受器机制的明适应特性。采用心率条件反射技术测定了分离的视锥和视杆机制的阈值与背景强度（TVI）曲线。本研究的主要目的是比较金鱼对紫外线（UV）敏感的视锥机制与其他感受器机制的明适应特性。这项研究揭示了几个显著的功能差异：（1）对紫外线敏感的视锥机制的阈值与背景强度（TVI）曲线斜率为0.65（在对数/对数图上，其他视锥机制的斜率约为1.0），因此不符合韦伯定律。这可能部分与在较高辐射范围内蓝光敏感机制的干扰有关。（2）对紫外线敏感的视锥机制的作用限于中等强度（即不太暗或不太亮）。（3）对紫外线敏感的视锥机制的韦伯分数或亮度对比阈值为0.316，约为其他视锥机制的六倍，但与视杆机制相当。这表明在亮度对比检测方面，对紫外线敏感的视锥机制表现相对较差。
