Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
J Comp Neurol. 2012 Jun 1;520(8):1599-628. doi: 10.1002/cne.23054.
Each fall, eastern North American monarch butterflies (Danaus plexippus) use a time-compensated sun compass to migrate to their overwintering grounds in central Mexico. The sun compass mechanism involves the neural integration of skylight cues with timing information from circadian clocks to maintain a constant heading. The neuronal substrates for the necessary interactions between compass neurons in the central complex, a prominent structure of the central brain, and circadian clocks are largely unknown. To begin to unravel these neural substrates, we performed 3D reconstructions of all neuropils of the monarch brain based on anti-synapsin labeling. Our work characterizes 21 well-defined neuropils (19 paired, 2 unpaired), as well as all synaptic regions between the more classically defined neuropils. We also studied the internal organization of all major neuropils on brain sections, using immunocytochemical stainings against synapsin, serotonin, and γ-aminobutyric acid. Special emphasis was placed on describing the neuroarchitecture of sun-compass-related brain regions and outlining their homologies to other migratory species. In addition to finding many general anatomical similarities to other insects, interspecies comparison also revealed several features that appear unique to the monarch brain. These distinctive features were especially apparent in the visual system and the mushroom body. Overall, we provide a comprehensive analysis of the brain anatomy of the monarch butterfly that will ultimately aid our understanding of the neuronal processes governing animal migration.
每年秋季，北美东部黑脉金斑蝶（Danaus plexippus）利用时间补偿的太阳罗盘导航，迁徙到墨西哥中部的越冬地。太阳罗盘机制涉及到日光线索与生物钟计时信息的神经整合，以保持恒定的朝向。中央复合体（中枢大脑的一个突出结构）中的罗盘神经元与生物钟之间必要的相互作用的神经元基质在很大程度上是未知的。为了开始揭示这些神经基质，我们基于抗突触素标记对帝王蝶大脑的所有神经节进行了 3D 重建。我们的工作描述了 21 个定义明确的神经节（19 对，2 个非对），以及在更经典定义的神经节之间的所有突触区域。我们还使用针对突触素、血清素和γ-氨基丁酸的免疫细胞化学染色，研究了所有主要神经节在脑切片上的内部组织。特别强调描述与太阳罗盘相关的大脑区域的神经结构，并概述它们与其他迁徙物种的同源性。除了发现与其他昆虫有许多一般的解剖相似之处外，种间比较还揭示了几个似乎是帝王蝶大脑特有的特征。这些独特的特征在视觉系统和蘑菇体中尤为明显。总的来说，我们提供了对帝王蝶大脑解剖结构的全面分析，这将最终有助于我们理解控制动物迁徙的神经元过程。
