Chair of Zoology 2, Würzburg University, Am Hubland, 97074 Würzburg, Germany.
Chair of Zoology 2, Würzburg University, Am Hubland, 97074 Würzburg, Germany.
Curr Biol. 2021 Mar 22;31(6):R280-R281. doi: 10.1016/j.cub.2021.02.022.
Many animals use visual cues to navigate their environment. To encode the large input ranges of natural signals optimally, their sensory systems have adapted to the stimulus statistics experienced in their natural habitats. A striking example, shared across animal phyla, is the retinal tuning to the relative abundance of blue light from the sky, and green light from the ground, evident in the frequency of each photoreceptor type in the two retinal hemispheres. By adhering only to specific regions of the visual field that contain the relevant information, as for the high-acuity dorsal regions in the eyes of male flies chasing females, the neural investment can be further reduced. Regionalisation can even lead to activation of the appropriate visual pathway by target location, rather than by stimulus features. This has been shown in fruit flies, which increase their landing attempts when an expanding disc is presented in their frontal visual field, while lateral presentation increases obstacle avoidance responses. We here report a similar switch in behavioural responses for extended visual scenes. Using a free-flight paradigm, we show that the hummingbird hawkmoth (Macroglossum stellatarum) responds with flight-control adjustments to translational optic-flow cues exclusively in their ventral and lateral visual fields, while identical stimuli presented dorsally elicit a novel directional flight response. This response split is predicted by our quantitative imaging data from natural visual scenes in a variety of habitats, which demonstrate higher magnitudes of translational optic flow in the ventral hemisphere, and the opposite distribution for contrast edges containing directional information.
许多动物利用视觉线索来导航环境。为了优化地对自然信号的大范围输入进行编码，它们的感觉系统已经适应了在自然栖息地中所经历的刺激统计数据。一个显著的例子是，在动物门中共享的，是视网膜对来自天空的蓝光和来自地面的绿光的相对丰度的调谐，这在两个视网膜半球中每种光感受器类型的频率上显而易见。通过仅粘附于包含相关信息的视野的特定区域，例如雄性苍蝇追逐雌性时眼睛的高敏度背侧区域，可以进一步减少神经投入。区域化甚至可以导致通过目标位置而不是通过刺激特征来激活适当的视觉通路。这在果蝇中已经得到证实，当在其前视野中呈现扩展的圆盘时，它们会增加着陆尝试，而侧向呈现则会增加障碍物回避反应。我们在这里报告了对扩展视觉场景的类似行为反应的转变。使用自由飞行范式，我们表明，蜂鸟鹰蛾（Macroglossum stellatarum）仅对其腹侧和侧面视觉场中的平移光流线索做出飞行控制调整的反应，而相同的刺激在背部呈现则会引发新的定向飞行反应。这种反应分裂是由我们从各种栖息地的自然视觉场景中的定量成像数据预测的，这些数据表明腹侧半球的平移光流幅度更高，而包含方向信息的对比度边缘则具有相反的分布。
