How external cues modulate the behavioral output of an animal:Immediate effects of light on rhythmic eclosion behavior in Drosophila

适当的日常行为时间对于动物的健康至关重要。光以两种方式影响日常计时：(1)光强度的周期性变化作为一个携带信号，使内源性(昼夜)计时系统同步，使生物体适当地适应24小时的环境周期；(2)光通过提高包括人类在内的白天动物的警觉性、运动性、体温和心率，以及通过抑制夜间动物的活动和促进睡眠，直接调节行为。这些即时的光效应与生物钟无关，因为它们常常遮蔽(“掩蔽”)生物钟的行为，所以它们也被称为生物钟的“掩蔽”效应。即刻的光效应对于动物对环境变化的适当反应和增强行为输出是必不可少的。在黑腹果蝇中，即时的光效应是由眼睛调节的，最明显的是苍蝇行为节律中的点亮反应--成虫从蛹中出现的节律，称为羽化。羽化被生物钟控制到最早，以防止干燥和提高存活率。光刺激会导致羽化率的快速增加，在这里，我们将用羽化作为行为读数来描述外部光刺激对黑腹果蝇神经回路的潜在影响。我们的目标是利用遗传学、行为分析、光学显微镜和活细胞成像来揭示即时光反应的神经元原理。拟议中的项目将首次解开即时光反应背后的神经元机制，从而为外部线索如何调节动物的大脑活动和行为输出的基本原理提供新的见解。

An appropriate daily timing of behavior is of critical importance for animal fitness. Light shapes the daily timing in two ways: (1) the cyclic change in light intensity acts as an entraining signal, synchronizing the endogenous (circadian) timing system to appropriately adjust an organism to the 24h environmental period; (2) light directly modulates behavior by increasing alertness, locomotion, body temperature and heart rate in diurnal animals including humans and by suppressing activity and promoting sleep in nocturnal animals. These immediate light effects are independent of the circadian clock and since they often obscure (“mask”) circadian behaviors, they are also called “masking” effects of the clock. The immediate light effects are essential for appropriate responses of the animal to changes in the environment and for sharpening the behavioral output. In Drosophila melanogaster, the immediate light effects are mediated by the eyes and most evident as a lights-on response in a well described behavioral rhythm of the fly – the emergence rhythm of the adult insect from the pupa, called eclosion. Eclosion is gated by the circadian clock to the early day to prevent desiccation and enhance survival rate. A light stimulus induces a rapid increase in eclosion rate, the lights-on effect.Here we will use eclosion as a behavioral readout to describe the neuronal circuitry underlying effects of external light stimuli in Drosophila melanogaster. We aim to unravel the neuronal principles of immediate light responses using genetics, behavioral analysis, light microscopy and live cell imaging. The proposed project will - for the first time - untangle the neuronal mechanisms underlying immediate light responses and thereby give novel insights into the fundamental principles of how external cues modulate the brain activity and, thus, the behavioral output of animals.