Institute of Developmental Biology and Neurobiology, Johannes Gutenberg-Universität Mainz, Hanns-Dieter-Hüsch-Weg 15, Mainz 55128, Germany; European Neuroscience Institute Göttingen, a Joint Initiative of the University Medical Center Göttingen and the Max Planck Society, Grisebachstr. 5, Göttingen 37077, Germany; International Max Planck Research School and Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB) at the University of Göttingen, Justus-von-Liebig-Weg 11, Göttingen 37077, Germany.
European Neuroscience Institute Göttingen, a Joint Initiative of the University Medical Center Göttingen and the Max Planck Society, Grisebachstr. 5, Göttingen 37077, Germany.
Curr Biol. 2020 Feb 24;30(4):657-669.e4. doi: 10.1016/j.cub.2019.12.038. Epub 2020 Jan 30.
Visual perception scales with changes in the visual stimulus, or contrast, irrespective of background illumination. However, visual perception is challenged when adaptation is not fast enough to deal with sudden declines in overall illumination, for example, when gaze follows a moving object from bright sunlight into a shaded area. Here, we show that the visual system of the fly employs a solution by propagating a corrective luminance-sensitive signal. We use in vivo 2-photon imaging and behavioral analyses to demonstrate that distinct OFF-pathway inputs encode contrast and luminance. Predictions of contrast-sensitive neuronal responses show that contrast information alone cannot explain behavioral responses in sudden dim light. The luminance-sensitive pathway via the L3 neuron is required for visual processing in such rapidly changing light conditions, ensuring contrast constancy when pure contrast sensitivity underestimates a stimulus. Thus, retaining a peripheral feature, luminance, in visual processing is required for robust behavioral responses.
视觉感知与视觉刺激（对比度）的变化成正比，而与背景照明无关。然而，当适应速度不够快，无法应对整体照明的突然下降时，例如，当目光从明亮的阳光跟随移动物体进入阴影区域时，视觉感知就会受到挑战。在这里，我们展示了果蝇的视觉系统通过传播校正的亮度敏感信号来解决这个问题。我们使用在体 2 光子成像和行为分析来证明不同的 OFF 通路输入可以编码对比度和亮度。对对比度敏感神经元反应的预测表明，仅对比度信息不能解释在突然变暗的光线下的行为反应。通过 L3 神经元的亮度敏感通路在这种快速变化的光照条件下对视觉处理是必需的，确保了在纯对比度敏感度低估刺激时对比度的恒定性。因此，在视觉处理中保留外围特征亮度对于稳健的行为反应是必需的。
