背侧中缝核5-羟色胺能神经元通过其广泛的神经投射影响大脑多方面的功能，包括抑郁和焦虑、睡眠-觉醒周期、奖赏、决策中的耐心以及性别取向等。在受背侧中缝核5-羟色胺能神经元调制的脑区中，嗅球是接受最多神经输入的脑区之一，提示5-羟色胺能神经元能显著调制嗅球的功能活动。先前的行为药理学研究表明背侧中缝核的5-羟色胺能神经投射能影响气味相关的联合性学习以及短时程记忆；同时，电生理研究表明5-羟色胺能调制嗅球内各类细胞的功能活动。然而，由于缺乏有效的特异性操控5-羟色胺能神经元活动的方法，这些研究仅能提供间接实验证据。本研究拟使用光遗传技术特异性激活背侧中缝核5-羟色胺能神经元，并结合药理学、离体和在体电生理记录以及行为学手段，研究5-羟色胺能神经元对嗅球和嗅觉学习记忆行为的调制及其内在神经机制。研究结果能为5-羟色胺能神经元如何调节嗅觉功能提供直接证据，并加深我们对嗅觉感知过程的理解。

Serotonergic neurons from dorsal raphe nucleus are involved in a variety of brain functions by their extensive neural innervation, including depression, anxiety, sleep-wake cycles, reward, patience in decision making, and sexual preference. Among the brain areas that modulated by serotonergic neurons, olfactory bulb is one of the area that contains the most dense innervation input, indicating that serotonergic neurons can dramatically modulate the function and activity of olfactory bulb. By combining animal behavior and pharmacy methods, previous studies indicated that serotonergic projections to olfactory bulb influenced odor related associated learning and short term memory. Meanwhile, electrophysiological studies have shown some modulation effects of serotonin on different types of neurons in the olfactory bulb. However, all these studies only provided indirect evidence of how serotonergic neurons affected olfactory bulb, since an effective technique to manipulate serotonergic neurons specifically was lacking. This proposal will use the optogenetic technique to activate serotonergic neurons in dorsal raphe nucleus specifically, and combine pharmacy, in vitro and in vivo electrophysiological recordings and animal behavior to study how serotonergic neurons modulated the function of olfactory bulb and olfaction related learning and memeory, and underling neural mechanisms. The results will provide direct evidence of how serotonergic neurons modulate olfaction, and deepen our understanding of the process of olfactory perception.