Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway.
Laboratory for Neural Computation, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
J Comp Neurol. 2021 May 1;529(7):1516-1540. doi: 10.1002/cne.25034. Epub 2020 Oct 5.
The relatively large primary olfactory center of the insect brain, the antennal lobe (AL), contains several heterogeneous neuronal types. These include projection neurons (PNs), providing olfactory information to higher-order neuropils via parallel pathways, and local interneurons (LNs), which provide lateral processing within the AL. In addition, various types of centrifugal neurons (CNs) offer top-down modulation onto the other AL neurons. By performing iontophoretic intracellular staining, we collected a large number of AL neurons in the moth, Helicoverpa armigera, to examine the distinct morphological features of PNs, LNs, and CNs. We characterize 190 AL neurons. These were allocated to 25 distinct neuronal types or sub-types, which were reconstructed and placed into a reference brain. In addition to six PN types comprising 15 sub-types, three LN and seven CN types were identified. High-resolution confocal images allowed us to analyze AL innervations of the various reported neurons, which demonstrated that all PNs innervating ventroposterior glomeruli contact a protocerebral neuropil rarely targeted by other PNs, that is the posteriorlateral protocerebrum. We also discuss the functional roles of the distinct CNs, which included several previously uncharacterized types, likely involved in computations spanning from multisensory processing to olfactory feedback signalization into the AL.
昆虫大脑中相对较大的初级嗅觉中枢——触角叶（antennal lobe，AL）包含几种异质神经元类型。这些类型包括投射神经元（projection neurons，PNs），通过平行途径将嗅觉信息提供给高级神经节；以及局部中间神经元（local interneurons，LNs），它们在 AL 内提供侧向处理。此外，各种类型的离心神经元（centrifugal neurons，CNs）为其他 AL 神经元提供自上而下的调制。通过进行离子电泳细胞内染色，我们在鳞翅目昆虫棉铃虫（Helicoverpa armigera）中收集了大量的 AL 神经元，以检查 PNs、LNs 和 CNs 的不同形态特征。我们鉴定了 190 个 AL 神经元。这些神经元被分配到 25 种不同的神经元类型或亚型中，我们对其进行了重建并放置在参考大脑中。除了包含 15 个亚型的六种 PN 类型外，还鉴定出三种 LN 和七种 CN 类型。高分辨率共聚焦图像使我们能够分析各种报道神经元在 AL 中的神经支配，结果表明，所有投射到腹后外侧神经节的 PN 都与一个很少被其他 PN 靶向的脑前神经节接触，即后外侧脑前体。我们还讨论了不同 CN 的功能作用，其中包括几种以前未被表征的类型，它们可能参与从多感觉处理到嗅觉反馈信号化到 AL 的计算。
