Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Shanghai 200031, China.
Proc Natl Acad Sci U S A. 2014 Feb 25;111(8):3164-9. doi: 10.1073/pnas.1317911111. Epub 2014 Feb 10.
In insects, olfactory information received by peripheral olfactory receptor neurons (ORNs) is conveyed from the antennal lobes (ALs) to higher brain regions by olfactory projection neurons (PNs). Despite the knowledge that multiple types of PNs exist, little is known about how these different neuronal pathways work cooperatively. Here we studied the Drosophila GABAergic mediolateral antennocerebral tract PNs (mlPNs), which link ipsilateral AL and lateral horn (LH), in comparison with the cholinergic medial tract PNs (mPNs). We examined the connectivity of mlPNs in ALs and found that most mlPNs received inputs from both ORNs and mPNs and participated in AL network function by forming gap junctions with other AL neurons. Meanwhile, mlPNs might innervate LH neurons downstream of mPNs, exerting a feedforward inhibition. Using dual-color calcium imaging, which enables a simultaneous monitoring of neural activities in two groups of PNs, we found that mlPNs exhibited robust odor responses overlapping with, but broader than, those of mPNs. Moreover, preferentially down-regulation of GABA in most mlPNs caused abnormal courtship and aggressive behaviors in male flies. These findings demonstrate that in Drosophila, olfactory information in opposite polarities are carried coordinately by two parallel and interacted pathways, which could be essential for appropriate behaviors.
在昆虫中，由外周嗅觉受体神经元（ORNs）接收的嗅觉信息通过嗅觉投射神经元（PNs）从触角叶（ALs）传递到大脑的更高区域。尽管已知存在多种类型的 PNs，但对于这些不同的神经元通路如何协同工作知之甚少。在这里，我们研究了果蝇 GABA 能的mediolateral antennocerebral 束 PNs（mlPNs），它们连接同侧的 AL 和 lateral horn（LH），并与胆碱能的 medial tract PNs（mPNs）进行了比较。我们检查了 mlPNs 在 AL 中的连接性，发现大多数 mlPNs 接收来自 ORNs 和 mPNs 的输入，并通过与其他 AL 神经元形成缝隙连接而参与 AL 网络功能。同时，mlPNs 可能会在 mPNs 的下游 innervate LH 神经元，施加前馈抑制。使用双色钙成像，可以同时监测两组 PNs 的神经活动，我们发现 mlPNs 表现出强烈的气味反应，与 mPNs 的反应重叠，但更广泛。此外，大多数 mlPNs 中 GABA 的优先下调导致雄蝇出现异常的求爱和攻击行为。这些发现表明，在果蝇中，相反极性的嗅觉信息由两条平行且相互作用的通路协调传递，这对于适当的行为可能是必不可少的。
