Lall A B
Department of Biology, Howard University, Washington, D.C. 20059.
J Exp Zool. 1993 Apr 1;265(5):609-12. doi: 10.1002/jez.1402650518.
Changes in visual sensitivity as a function of time-of-day were studied in the firefly Photuris versicolor. The electroretinograms (ERGs) elicited by photic stimuli of constant intensity and duration were recorded over long periods (18-52 h) while the insect was in constant darkness. The amplitudes of the ERGs elicited by the standard flash were small and remained constant during the daytime hours and increased on average sixfold during the evening hours, reaching a maximum at the onset of darkness and remaining at that high level until the morning hours. The amplitude of the standard response again was reduced in the morning hours to a daytime low value which again persisted until the following evening (Fig. 1). In addition, a series of flashes of varying intensity were administered periodically and logV/logI curves as a function of time-of-day were obtained. Compared to the daytime logV/logI curves, the nighttime curves were shifted about 4 log units towards the left on the intensity axis (Fig. 2). This period of high visual sensitivity was correlated with the species' flashing activity period, which occurs during the night hours (Fig. 1).
研究了多变光萤（Photuris versicolor）视觉敏感度随一天中不同时间的变化情况。在昆虫处于持续黑暗环境时，长时间（18 - 52小时）记录由恒定强度和持续时间的光刺激诱发的视网膜电图（ERG）。标准闪光诱发的ERG振幅在白天较小且保持恒定，在傍晚时分平均增加六倍，在黑暗开始时达到最大值，并在该高水平持续到早晨。标准反应的振幅在早晨又降至白天的低值，并再次持续到第二天晚上（图1）。此外，定期给予一系列不同强度的闪光，并获得了作为一天中不同时间函数的logV/logI曲线。与白天的logV/logI曲线相比，夜间曲线在强度轴上向左移动了约4个对数单位（图2）。这种高视觉敏感度的时期与该物种在夜间发生的闪光活动期相关（图1）。
