Champalimaud Research, Champalimaud Centre for the Unknown, Lisbon, Portugal.
PLoS Biol. 2019 Jan 17;17(1):e2006749. doi: 10.1371/journal.pbio.2006749. eCollection 2019 Jan.
In flies, the olfactory information is carried from the first relay in the brain, the antennal lobe, to the mushroom body (MB) and the lateral horn (LH). Olfactory associations are formed in the MB. The LH was ascribed a role in innate responses based on the stereotyped connectivity with the antennal lobe, stereotyped physiological responses to odors, and MB silencing experiments. Direct evidence for the functional role of the LH is still missing. Here, we investigate the behavioral role of the LH neurons (LHNs) directly, using the CO2 response as a paradigm. Our results show the involvement of the LH in innate responses. Specifically, we demonstrate that activity in two sets of neurons is required for the full behavioral response to CO2. Tests of the behavioral response to other odors indicate the neurons are selective to CO2 response. Using calcium imaging, we observe that the two sets of neurons respond to CO2 in a different manner. Using independent manipulation and recording of the two sets of neurons, we find that the one that projects to the superior intermediate protocerebrum (SIP) also outputs to the local neurons within the LH. The design of simultaneous output at the LH and the SIP, an output of the MB, allows for coordination between innate and learned responses.
在果蝇中，嗅觉信息从大脑的第一个中继站，触角叶，传递到蘑菇体（MB）和侧角（LH）。嗅觉联想在 MB 中形成。基于与触角叶的刻板连接、对气味的刻板生理反应以及 MB 沉默实验，LH 被归因于先天反应的作用。LH 的功能作用的直接证据仍然缺失。在这里，我们使用 CO2 反应作为范例，直接研究 LH 神经元（LHNs）的行为作用。我们的结果表明 LH 参与了先天反应。具体来说，我们证明了两组神经元的活动对于对 CO2 的完全行为反应是必需的。对其他气味的行为反应测试表明，神经元对 CO2 反应具有选择性。使用钙成像，我们观察到两组神经元以不同的方式对 CO2 作出反应。使用两组神经元的独立操作和记录，我们发现投射到上中间脑的那一组神经元也向 LH 内的局部神经元输出。LH 和 MB 的 SIP 同时输出的设计允许先天和学习反应之间的协调。
