Faculty of Biology, Animal Physiology & Center for Mind, Brain and Behavior - CMBB, Philipps-Universität Marburg, Marburg, Germany.
J Comp Neurol. 2018 Oct 1;526(14):2301-2318. doi: 10.1002/cne.24497. Epub 2018 Sep 21.
The central complex is a group of midline-crossing neuropils in the insect brain involved in head direction coding, sky compass navigation, and spatial visual memory. To compare the neuroarchitecture and neurochemistry of the central complex in insects that differ in locomotion, ways of orientation, time of activity (diurnal, nocturnal), and evolutionary history, we studied the distribution of γ-aminobutyric acid (GABA) immunostaining in the central complex of 29 species, ranging from Zygentoma to Diptera. In all species, the lower division of the central body was densely innervated by GABA-immunoreactive tangential neurons. These neurons had additional arborizations in the bulb, a distinct region of synaptic complexes in the lateral complex, and somata in a cell cluster mediodorsally to the antennal lobe. Differences in the appearance of GABA immunostaining in the lower division of the central body corresponded to differences in neuropil architecture, such as transformation of the lower division into a toroid in certain Diptera and Heteroptera. In nearly all species two additional systems of tangential neuron of the upper division of the central body were GABA-immunoreactive. One of these systems diffusely invaded a superior layer, while the second system showed fan-like projections in an inferior layer. Sparse immunostaining in the protocerebral bridge was detected in cockroaches, a cricket, and two hemipteran species. The data show that three systems of GABA-immunoreactive tangential neurons of the central body are highly conserved and suggest that the layered organization of the upper division of the central body is, likewise, largely maintained from basal to advanced species.
中央复合神经系统是昆虫大脑中一组中线交叉神经节，参与头部方向编码、天空罗盘导航和空间视觉记忆。为了比较在运动方式、定向方式、活动时间（昼夜）和进化历史上不同的昆虫中央复合神经系统的神经结构和神经化学，我们研究了 29 种昆虫中央复合神经系统中γ-氨基丁酸（GABA）免疫染色的分布范围，从原尾目到双翅目。在所有物种中，中央体的下部都被 GABA 免疫反应性切线神经元密集支配。这些神经元在球状体中有额外的分支，球状体是侧复合神经系统中一个独特的突触复合体区域，并且在触角叶背侧中线附近的细胞群中有体。中央体下部 GABA 免疫染色的外观差异与神经节结构的差异相对应，例如某些双翅目和半翅目昆虫的中央体下部转变为环。在几乎所有物种中，中央体上部还有另外两个系统的切线神经元呈 GABA 免疫反应性。其中一个系统弥漫地入侵一个上层，而第二个系统在上层呈现扇形投射。在蟑螂、蟋蟀和两种半翅目昆虫中检测到中脑桥上稀疏的免疫染色。这些数据表明，中央体的三个系统的 GABA 免疫反应性切线神经元高度保守，并表明中央体上部的分层组织在从基础到高级物种中也得到了很大的维持。
