环境温度对动物的寿命、体重、感知疼痛、昼夜节律行为等都有着深远的影响。动物温度感知系统高度保守，但其神经信号传导机制仍不清晰。果蝇因其相对简单的组织结构，极其丰富的遗传学和生理学工具，成为研究感温系统的优势模式生物。本项目将对果蝇脑内感热Ventrolateral Protocerebrum（VLP）神经元进行研究。预实验结果表明，其感热反应特点与目前唯一已知的脑内感热Anterior Cells（ACs）有显著不同，结构上不存在突触连接。VLP或是有别于ACs独立存在的另一类脑内感热神经元，或为ACs的下游。由于其与生物钟细胞可形成突触连接，我们推测其为生物钟温度循环感受器，调节生物钟节律。此项目将记录VLP神经元感热反应、研究其感温信号传导机制、分析其感热反应对果蝇的行为学意义。此项目的完成，将揭示果蝇脑内热感知神经元的作用机理，可为今后对更复杂温度感知系统的分析提供基础。

Environmental temperature has a profound impact on animal longevity, body weight, the ability to sense pain and circadian behaviors. Temperature sensors are evolutionally conserved. However, it is unclear how a range of temperature information is processed and integrated into neuronal circuits. The fruit flies provide an attractive system to study thermosensation because they offer a relatively simple biological system coupled with powerful genetic and physiological tools. So far, Anterior Cells (ACs) are only reported internal temperature sensitive neurons in the fly brain. In this project, we identified a small set of internal warmth-activated Ventrolateral Protocerebrum (VLP) neurons. Our current results showed that the VLP neurons and ACs have different temperature dependent responses. They do not have structural connections. Therefore, we hypothesize that they could contribute to distinct thermal sensing pathways, or VLP might be the downstream neurons of ACs. The structural connection between VLP neurons and circadian pacemaker neurons demonstrate that VLP neurons could be internal thermosensory neurons for environmental cycles of temperature, modulating circadian locomotion activity rhythms. In this project, neuronal circuits and functional effects of VLP neurons will be analyzed. Firstly, the physiological responses of VLP neurons to temperature increases will be determined. Then, we will test the possible up/downstream signaling cascade. At last, we will analyze how this temperature sensor contribute to Drosophila behaviors. The accomplishment of this project will reveal the neuronal mechanism of internal thermal sensory neurons in Drosophila and provide the groundwork of thermal sensation for the subsequent analysis of more complex systems.