Thoss Friederike M, Ballosek Simone, Bartsch Bengt, Thoss Franz T
Carl-Ludwig-Institute of Physiology of the University of Leipzig, Liebigstr. 27, 04103 Leipzig, Germany.
Vision (Basel). 2018 Feb 19;2(1):10. doi: 10.3390/vision2010010.
The excitation of the visual system increases with increasing retinal illumination. At the same time, the sensitivity of the system decreases (light adaptation). Higher excitation automatically results in a lower sensitivity. This study investigates whether this antagonistic relationship between excitation and sensitivity also applies to the dynamic case, that is, during the transition to a higher excitation level after a sudden increase in retinal illuminance. For this purpose, the courses of the subjective and the electroretinographic threshold in the transitional period during and after a step of the adaptation illuminance were investigated by means of a special light-stimulation system. The investigation was carried out on 9 (subjective threshold) and 12 (electroretinographic threshold) subjects. As a measure of the course of the excitation during this time, the response ERG on the adaptation step was recorded. With the step in adaptation light, the thresholds show a rapid increase, which starts already about 0.1 s before the step. This is followed, within the next second, by a threshold decrease to a new plateau above the initial level. The comparison between the response ERG on the adaptation step and the course of the electroretinographic increment threshold during this time shows a broad agreement between the two courses. Thus, it can be assumed that the sensitivity of the visual system also follows the excitation in the dynamic case. In addition, the investigation shows that the glare experienced after a step in illuminance apparently shows great subjective differences.
视觉系统的兴奋程度随视网膜光照度的增加而增强。与此同时，该系统的敏感度降低（明适应）。较高的兴奋程度必然导致较低的敏感度。本研究旨在探究兴奋与敏感度之间的这种拮抗关系是否也适用于动态情况，即在视网膜照度突然增加后向更高兴奋水平转变的过程中。为此，借助一种特殊的光刺激系统，研究了适应照度阶跃期间及之后过渡期内主观阈值和视网膜电图阈值的变化过程。该研究针对9名（主观阈值）和12名（视网膜电图阈值）受试者展开。作为这段时间内兴奋过程的一种度量，记录了适应阶跃时的视网膜电图反应。随着适应光的阶跃变化，阈值迅速升高，在阶跃前约0.1秒就已开始。随后，在接下来的一秒内，阈值下降至高于初始水平的新平稳状态。适应阶跃时的视网膜电图反应与此时视网膜电图增量阈值变化过程的比较表明，两者变化过程大致相符。因此，可以假定在动态情况下视觉系统的敏感度也随兴奋程度而变化。此外，研究表明，照度阶跃后所经历的眩光在主观感受上显然存在很大差异。
