Spatial resolution is a key property of eyes when it comes to understanding how animals' visual signals are perceived. This property can be robustly estimated by measuring the contrast sensitivity as a function of different spatial frequencies, defined as the number of achromatic vertical bright and dark stripe pairs within one degree of visual angle. This contrast sensitivity function (CSF) has been estimated for different animal groups, but data on fish are limited to two free-swimming, freshwater species (i.e., goldfish and bluegill sunfish). In this study, we describe the CSF of a small marine cryptobenthic fish (Tripterygion delaisi) using an optokinetic reflex approach. Tripterygion delaisi features a contrast sensitivity that is as excellent as other fish species, up to 125 (reciprocal of Michelson contrast) at the optimal spatial frequency of 0.375 c/°. The maximum spatial resolution is instead relatively coarse, around 2.125 c/°. By comparing our results with acuity values derived from anatomical estimates of ganglion cells' density, we conclude that the optokinetic reflex seems to be adapted to process low spatial frequency information from stimuli in the peripheral visual field and show that small marine fish can feature excellent contrast sensitivity at optimal spatial frequency.
展开▼
机译：在理解动物视觉信号的感知方面，空间分辨率是眼睛的关键属性。通过根据不同空间频率（定义为一个视角内消色差垂直亮和暗条纹对的数量）测量对比度敏感度，可以可靠地估计此属性。已经针对不同的动物组估计了这种对比敏感度函数（CSF），但是有关鱼类的数据仅限于两种自由游动的淡水物种（即金鱼和蓝g翻车鱼）。在这项研究中，我们描述了一种使用光动力学反射方法的小型海洋隐栖鱼类（Tripterygion delaisi）的CSF。雷公藤的特征是对比度灵敏度与其他鱼类一样好，在最佳空间频率为0.375 c /°时可达125（迈克尔逊对比度的倒数）。相反，最大空间分辨率相对较高，约为2.125 c /°。通过将我们的结果与神经节细胞密度的解剖学估计得出的敏锐度值进行比较，我们得出结论，视动反射似乎可以适应周围视野中刺激产生的低空间频率信息，并表明小型海鱼可以表现出出色的对比度在最佳空间频率下的灵敏度。
展开▼
